Optoelectronic detection device, its testing method and method for reducing the influence of dark current

Abstract

An optoelectronic detection device, a test method thereof, and a method for reducing the influence of dark current are disclosed, which relate to electro-optical devices and lasers used in infrared photonics. The optoelectronic detection device includes: an active photosensitive site including an active photodiode; a reference photosensitive site including a reference photodiode; a first voltage-controlled current circuit composed of a voltage-controlled current source or a voltage-controlled current sink, the first voltage-controlled current circuit being coupled to the active photodiode; and a control voltage generation circuit coupled to the active voltage-controlled current circuit and the reference photosensitive site and configured to provide a control voltage to the voltage-controlled current circuit, the control voltage having a voltage level that responds to the dark current of the reference photodiode to reduce the influence of the dark current of the active photodiode on the output of the active photosensitive site.

Description

[0001] This application is a divisional application of the application with the application number 202080005868.4 (PCT application number PCT / IB2020 / 060011), the application date of October 24, 2020, and the invention title "Photon System and Method".

[0002] Cross - Reference to Related Applications

[0003] This application is related to U.S. Patent Application No. 16 / 662,665 filed on October 24, 2019, and U.S. Provisional Patent Application Nos. 63 / 075,426 filed on September 8, 2020, 63 / 093,945 filed on October 20, 2020, and 63 / 094,913 filed on October 22, 2020, and claims the priority thereof, and all of the content is incorporated herein by reference in its entirety. Technical Field

[0004] The present disclosure relates to photon systems, methods, and computer program products. More specifically, the present disclosure relates to electro-optic devices and lasers used in infrared (IR) photons. Background Art

[0005] Optoelectronic detection devices such as photodetector arrays (also referred to as "photosensor arrays") include a multitude of photosites, each photosite including one or more photodiodes and capacitors, the one or more photodiodes being used to detect impinging light, and the capacitors being used to store the charge provided by the photodiodes. The capacitors can be implemented as a dedicated capacitor and / or using the parasitic capacitance of the photodiodes, transistors, and / or other components of the PS. Hereinafter, in this specification and for simplicity, the term "photodetecting device" is often replaced by the abbreviation "PDD", the term "photodetector array" is often replaced by the abbreviation "PDA", and the term "photodiode" is often replaced by the abbreviation "PD".

[0006] The term "photosite" refers to a single sensor element in an array of multiple sensors (also referred to as a "sensel", such as a combination of the words "sensor" and "cell" or "sensor" and "element"), and is also referred to as a "sensor element", "photosensor element", "photodetector element", etc. Hereinafter, "photosite" is generally replaced by the abbreviation "PS". Each PS may include: one or more PDs (for example, if a color filter array is implemented, multiple PDs that detect light in different parts of the spectrum may optionally be collectively referred to as a single PS). In addition to the PDs, the PS may also include: some circuitry or multiple additional components.

[0007] Dark current is a well-known phenomenon that, when referring to multiple PDs, is the current flowing through the PDs even when no photons enter the device. The dark current in multiple PDs may be caused by the random generation of electrons and holes in a depletion region of the PDs.

[0008] In some cases, there is a need to provide multiple photodiodes characterized by a relatively high dark current to multiple photosites while implementing capacitors with limited size. In some cases, there is a need to provide multiple PDs characterized by a relatively high dark current to multiple PSs while reducing the impact of the dark current on an output detection signal. In multiple PSs characterized by high dark current accumulation, it would be beneficial to address and overcome the harmful effects of the dark current on multiple electrooptical systems. Hereinafter and for simplicity, the term "electrooptical" may be replaced by the abbreviation "EO".

[0009] Short-wave infrared (SWIR) imaging enables a series of applications that are difficult to perform using visible light imaging. Many applications include electronic board inspection, solar cell inspection, product inspection, gated imaging, identification and classification, surveillance, anti-counterfeiting, process quality control, and more. Many existing SWIR imaging systems based on indium gallium arsenide (InGaAs) are expensive to manufacture and are currently limited by the available manufacturing capabilities.

[0010] Therefore, it would be beneficial to provide a SWIR imaging system that uses more cost-effective optical receivers based on multiple PDs that can be more easily integrated into surrounding electronic devices. Summary of the Invention

[0011] According to one aspect of the present disclosure, there is provided an active SWIR imaging system, which includes: a pulsed illumination source operable to emit a plurality of SWIR radiation pulses towards a target, the plurality of radiation pulses impinging on the target causing a plurality of reflected SWIR radiation pulses reflected from the target; an imaging receiver including a plurality of germanium (Ge) PDs operable to detect the reflected SWIR radiation, wherein the imaging receiver generates a corresponding detection signal representative of the reflected SWIR radiation impinging on the corresponding germanium PD for each germanium PD, a dark current greater than 50 microamperes per square centimeter (μA / cm 2 ), a time-dependent dark current noise, and a time-independent readout noise; and a controller operable to control the activation of the imaging receiver during an integration time, and the accumulated dark current noise during the integration time does not exceed the time-independent readout noise.

[0012] According to one aspect of the present disclosure, a method for generating a plurality of SWIR images of a plurality of objects in a field of view (FOV) of an EO system is disclosed. The method includes: emitting at least one illumination pulse towards the FOV, causing SWIR radiation to be reflected from at least one target; triggering continuous signal acquisition initiated by an imaging receiver, the imaging receiver including a plurality of germanium PDs operable to detect the reflected SWIR radiation; collecting, for each of the plurality of germanium PDs, the charge caused by triggering at least the SWIR reflected radiation to impinge on the corresponding germanium PD, a dark current greater than 50 μA / cm 2 , a dark current noise related to the integration time, and a readout noise independent of the integration time; triggering to stop the collection of the charge when the amount of charge collected due to the dark current noise is still lower than the amount of charge collected due to the readout noise independent of the integration time; and generating an image of the FOV based on the plurality of charge levels collected by each of the plurality of germanium PDs.

[0013] According to one aspect of the present disclosure, a SWIR optical system is disclosed. The SWIR system includes a passive Q-switch laser (also referred to herein as a "P-QS laser"), and the passive Q-switch laser includes: a gain medium including a gain medium crystal (GMC) material, the gain medium crystal material being ceramic neodymium-doped yttrium aluminum garnet (Nd:YAG); a saturable absorber (SA) rigidly coupled to the gain medium, the SA including a ceramic SA crystal material selected from a group of doped ceramic materials consisting of: V 3+ :YAG and various divalent cobalt-doped crystal materials; and an optical cavity, the gain medium and the SA being located in the optical cavity, the optical cavity including a high reflectivity mirror and an output coupler.

[0014] Hereinafter in this specification and for simplicity, the term "saturable absorber" is often replaced by the abbreviation "SA".

[0015] According to one aspect of the present disclosure, a SWIR optical system is disclosed. The SWIR system includes a P-QS laser, and the P-QS laser includes: a gain medium including a GMC material, the GMC material being ceramic Nd:YAG; an SA rigidly coupled to the gain medium, the SA including a ceramic SA crystal material selected from a group of doped ceramic materials consisting of: V 3+ :YAG and various divalent cobalt-doped crystal materials; and an optical cavity, the gain medium and the SA being located in the optical cavity, the optical cavity including a high reflectivity mirror and an output coupler.

[0016] According to one aspect of the present disclosure, a SWIR optical system is provided, which includes a P-QS laser. The P-QS laser includes: a gain medium, the gain medium including a ceramic GMC material, the ceramic GMC material being a ceramic neodymium-doped rare earth element crystal; a SA rigidly coupled to the gain medium, the SA including a ceramic SA crystal material selected from a group of doped crystal materials consisting of: V 3+ :YAG and various cobalt-doped crystal materials; and an optical cavity, the gain medium and the SA being located in the optical cavity, the optical cavity including a high reflectivity mirror and an output coupler.

[0017] According to one aspect of the present disclosure, a method for manufacturing a plurality of components of a P-QS laser is disclosed. The method includes: stuffing at least one first powder into a first mold; compacting the at least one first powder in the first mold to produce a first green body; stuffing at least one second powder different from the at least one first powder into a second mold; compacting the at least one second powder in the second mold to produce a second green body; heating the first green body to produce a first crystalline material; heating the second green body to produce a second crystalline material; and connecting the second crystalline material to the first crystalline material. In such a case, one of the first crystalline material and the second crystalline material is a neodymium-doped crystalline material and is a gain medium for the P-QS laser, and the other of the first crystalline material and the second crystalline material is an SA for the P-QS laser and is selected from a group of a plurality of crystalline materials consisting of: a neodymium-doped crystalline material and a doped crystalline material, the latter being selected from a group of a plurality of doped crystalline materials consisting of: V 3+ :YAG and various cobalt-doped crystalline materials. Also, in such a case, at least one of the gain medium and the SA is a ceramic crystalline material.

[0018] According to one aspect of the present disclosure, a PDD is disclosed, including: an active PS including an active PD; a reference PS including a reference PD; a first voltage-controlled current circuit composed of a voltage-controlled current source or a voltage-controlled current sink, the first voltage-controlled current circuit being connected to the active PD; and a control voltage generation circuit connected to the active voltage-controlled current circuit and the reference PS and configured to provide a control voltage to the voltage-controlled current circuit, the control voltage having a voltage level that responds to the dark current of the reference PD to reduce the influence of the dark current of the active PD on an output of the active PS.

[0019] According to one aspect of the present disclosure, a method for reducing the effects of dark current in a PDD is disclosed. The method includes: when the PDD is operating at a first temperature, determining a first control voltage based on the dark current of at least one reference PD of the PDD; providing the first control voltage to a first voltage-controlled current circuit of at least one active PD of an active PS connected to the PDD, thereby causing the first voltage-controlled current circuit to apply a first dark current suppression current in the active PS; generating a first detection current by the active PD in response to light impinging on the active PD from an object in a field of view of the PDD and the dark current generated by the active PD; and outputting a first detection signal by the active PS, the amplitude of the first detection signal being less than the first detection current, in response to the first detection current and the first dark current suppression current, thereby compensating for the effect of the dark current on the first detection signal; and when the PDD is operating at a second temperature that is at least 10 degrees Celsius (°C) higher than the first temperature, determining a second control voltage based on the dark current of at least one reference PD of the PDD; providing the second control voltage to the first voltage-controlled current circuit, thereby causing the first voltage-controlled current circuit to apply a second dark current suppression current in the active PS; generating a second detection current by the active PD in response to light impinging on the active PD from the object and the dark current generated by the active PD; and outputting a second detection signal by the active PS, the amplitude of the second detection signal being less than the second detection current, in response to the second detection current and the second dark current suppression current, thereby compensating for the effect of the dark current on the second detection signal. In such a case, an amplitude of the second dark current suppression current is greater than an amplitude of the first dark current suppression current by a factor of at least two.

[0020] According to one aspect of the present disclosure, a method for testing a PDD is disclosed. The method includes: providing a first voltage to a first input of an amplifier of a control voltage generation circuit, wherein a second input of the amplifier is coupled to a reference PD and a second current circuit, the second current circuit supplying a current at a level that is dominated to respond to an output voltage of the amplifier, thereby causing the amplifier to generate a first control voltage for a first current circuit of a PS for the PDD; reading a first output signal of the PS, the first output signal being generated by the PS in response to the current generated by the first current circuit and a PD of the PS; providing a second voltage different from the first voltage to the first input of the amplifier, thereby causing the amplifier to generate a second control voltage for a first current circuit; reading a second output signal of the PS, the second output signal being generated by the PS in response to the current generated by the first current circuit and a PD of the PS; and determining a defect state of a detection path of the PDD based on the first output signal and the second output signal, the detection path including the PS and a readout circuit associated with the PS.

[0021] According to one aspect of the present disclosure, a system for generating multiple images is disclosed. The system includes: a processor configured to: receive multiple detection results of an object from a PDA, the object including a high-reflectivity surface surrounded by multiple low-reflectivity surfaces on all sides, the multiple detection results including first frame information of the object detected by the PDA during a first frame exposure time and second frame information of the object detected by the PDA during a second frame exposure time, the second frame exposure time being longer than the first frame exposure time; process the first frame information based on the first frame exposure time to provide a first image, the first image including a bright region representing the high-reflectivity surface, the bright region being surrounded by a dark background representing the multiple low-reflectivity surfaces; and process the second frame information based on the second frame exposure time to provide a second image, the second image including a dark background without a bright region.

[0022] According to one aspect of the present disclosure, a system for generating multiple images is disclosed. The system includes: a processor configured to receive, from a PDA, multiple detection results of an object, the object including a high-reflectivity surface surrounded by multiple low-reflectivity surfaces on all sides, the multiple detection results including first-frame information of the object detected by the PDA during a first-frame exposure time and second-frame information of the object detected by the PDA during a second-frame exposure time, the second-frame exposure time being longer than the first-frame exposure time; process the first-frame information based on the first-frame exposure time to provide a first image, the first image including a bright region representing the high-reflectivity surface, the bright region being surrounded by a dark background representing the multiple low-reflectivity surfaces; and process the second-frame information based on the second-frame exposure time to provide a second image, the second image including a dark background without a bright region.

[0023] According to one aspect of the present disclosure, a method for generating image information based on data of a PDA is disclosed. The method includes: receiving, from a PDA, first-frame information of a low-reflectivity target including a high-reflectivity region, the first-frame information indicating multiple light intensities of multiple different parts of the target detected by the PDA during a first-frame exposure time; processing the first-frame information based on the first-frame exposure time to provide a first image, the first image including a bright region surrounded by a dark background; receiving, from the PDA, second-frame information of the low-reflectivity target including the high-reflectivity region, the second-frame information indicating multiple light intensities of the multiple different parts of the target detected by the PDA during a second-frame exposure time, the second-frame exposure time being longer than the first-frame exposure time; and processing the second-frame information based on the second-frame exposure time to provide a second image, the second image including a dark background without a bright region.

[0024] According to one aspect of the present disclosure, a non-transitory computer-readable medium is disclosed for generating image information based on data of a PDA. The non-transitory computer-readable medium includes a plurality of instructions stored thereon. When the plurality of instructions are executed on a processor, the following steps are performed: receiving, from a PDA, first frame information of a black target including a white area, the first frame information indicating a plurality of light intensities of a plurality of different parts of the target detected by the PDA during a first frame exposure time; processing the first frame information based on the first frame exposure time to provide a first image, the first image including a bright area surrounded by a dark background; receiving, from the PDA, second frame information of the black target including the white area, the second frame information indicating a plurality of indicated light intensities of the plurality of different parts of the target detected by the PDA during a second frame exposure time, the second frame exposure time being longer than the first frame exposure time; and processing the second frame information based on the second frame exposure time to provide a second image, the second image including a dark background without a bright area.

[0025] According to one aspect of the present disclosure, an EO system with dynamic PS availability assessment is disclosed. The system includes: a PDA including a plurality of photosensitive sites (PSs), each PS being operable to output a plurality of detection signals in a plurality of different frames, the detection signals output by the corresponding PS for a frame indicating the amount of light impinging on the corresponding PS in a corresponding frame; an availability filtering module operable to determine, for each PS, that the PS is unavailable based on a first frame exposure time and later determine that the PS is available based on a second frame exposure time, the second frame exposure time being shorter than the first frame exposure time; and a processor operable to generate a plurality of images based on the plurality of frame detection levels of the plurality of PSs. The processor is configured to: (i) exclude a first detection signal of a filtered PS determined by the availability filtering module to be unavailable for the first image when generating a first image based on a plurality of first frame detection levels, and (ii) include a second detection signal of the filtered PS determined by the availability filtering module to be available for the second image when generating a second image based on a plurality of second frame detection levels captured by the PDA after capturing the plurality of first frame detection levels.

[0026] According to one aspect of the present disclosure, a method for generating image information based on a PDA is disclosed. The method includes: receiving first frame information, the first frame information including a first frame detection level for each of a plurality of PSs of the PDA, the first frame detection level indicating a light intensity detected by each respective PS during a first frame exposure time; based on the first frame exposure time, identifying from the plurality of PSs of the PDD: a first available PS group including a first PS, a second PS, and a third PS, and a first unavailable PS group including a fourth PS; disregarding the plurality of first frame detection levels of the first unavailable PS group, and generating a first image based on the plurality of first frame detection levels of the first available PS group; after receiving the first frame information, determining a second frame exposure time, the second frame exposure time being longer than the first frame exposure time; receiving second frame information, the second frame information including a second frame detection level for each of the plurality of PSs of the PDA, the second frame detection level indicating a light intensity detected by each respective PS during a second frame exposure time; based on the second frame exposure time, identifying from the plurality of PSs of the PDD: a second available PS group including the first PS, and a second unavailable PS group including the second PS, the third PS, and the fourth PS; (g) disregarding the plurality of second frame detection levels of the second unavailable PS group, and generating a second image based on the plurality of second frame detection levels of the second available PS group; after receiving the second frame information, determining a third frame exposure time, the third frame exposure time being longer than the first frame exposure time and shorter than the second frame exposure time; receiving third frame information, the third frame information including a third frame detection level for each of the plurality of PSs of the PDA, the third frame detection level indicating a light intensity detected by each respective PS during a third frame exposure time; based on the third frame exposure time, identifying from the plurality of PSs of the PDD: a third available PS group including the first PS and the second PS, and a third unavailable PS group including the third PS and the fourth PS; and (k) disregarding the plurality of third frame detection levels of the third unavailable PS group, and generating a third image based on the plurality of third frame detection levels of the third available PS group.

[0027] According to one aspect of the present disclosure, a non-transitory computer-readable medium is disclosed for generating image information based on data from a photodetector array (PDA). The non-transitory computer-readable medium includes a plurality of instructions stored thereon, which when executed on a processor perform the following steps: receiving first frame information including a first frame detection level for each of a plurality of photosensors (PSs) of the PDA, the first frame detection level indicating a light intensity detected by each respective PS during a first frame exposure time; based on the first frame exposure time, identifying from the plurality of PSs of the PDD: a first available PS group including a first PS, a second PS, and a third PS, and a first unavailable PS group including a fourth PS; disregarding the first frame detection levels of the first unavailable PS group and generating a first image based on the first frame detection levels of the first available PS group; after receiving the first frame information, determining a second frame exposure time that is longer than the first frame exposure time; receiving second frame information including a second frame detection level for each of the plurality of PSs of the PDA, the second frame detection level indicating a light intensity detected by each respective PS during a second frame exposure time; based on the second frame exposure time, identifying from the plurality of PSs of the PDD: a second available PS group including the first PS, and a second unavailable PS group including the second PS, the third PS, and the fourth PS; disregarding the second frame detection levels of the second unavailable PS group and generating a second image based on the second frame detection levels of the second available PS group; after receiving the second frame information, determining a third frame exposure time that is longer than the first frame exposure time and shorter than the second frame exposure time; receiving third frame information including a third frame detection level for each of the plurality of PSs of the PDA, the third frame detection level indicating a light intensity detected by each respective PS during a third frame exposure time; based on the third frame exposure time, identifying from the plurality of PSs of the PDD: a third available PS group including the first PS and the second PS, and a third unavailable PS group including the third PS and the fourth PS; and disregarding the third frame detection levels of the third unavailable PS group and generating a third image based on the third frame detection levels of the third available PS group. Brief Description of the Drawings

[0028] The following describes non-limiting examples of the embodiments disclosed herein with reference to the accompanying drawings listed after this paragraph. The same structures, elements, or components that appear in more than one figure may be labeled with the same number in all the figures in which they appear. The accompanying drawings and the description are intended to illustrate and clarify the embodiments disclosed herein and should not be considered limiting in any way. All the drawings show apparatuses or flowcharts of numerous examples according to the presently disclosed subject matter. In the drawings:

[0029] Figure 1A , Figure 1B and Figure 1C are schematic block diagrams illustrating a plurality of active SWIR imaging systems.

[0030] Figure 2 is an exemplary graph illustrating the relative magnitudes of noise power after different durations of multiple integration times in a SWIR imaging system;

[0031] Figure 3A , Figure 3B and Figure 3C respectively show a flowchart and a plurality of schematic diagrams of an operating method of an active SWIR imaging system according to some embodiments;

[0032] Figure 4A , Figure 4B and Figure 4C respectively show a flowchart and a plurality of schematic diagrams of an exemplary operating method of an active SWIR imaging system;

[0033] Figure 5 is a flowchart illustrating a method for generating a plurality of SWIR images of a plurality of objects in a FOV of an EO system;

[0034] Figure 6 is a schematic functional block diagram showing an example of a SWIR optical system.

[0035] Figure 7A , Figure 7B and Figure 7C are schematic functional block diagrams illustrating a plurality of examples of P-QS lasers.

[0036] Figure 8 and Figure 9 are schematic functional diagrams illustrating a plurality of SWIR optical systems.

[0037] Figure 10 is a schematic functional block diagram showing an example of a SWIR optical system.

[0038] Figure 11A , Figure 11B and Figure 11CA flowchart and multiple conceptual timelines for performing the method are shown to illustrate an example of a method for manufacturing multiple components of a P-QS laser.

[0039] Figure 12A Schematically shows that a PS includes a PD, and the PD is controlled by a voltage-controlled current source;

[0040] Figure 12B Schematically shows that a PS includes a PD, and the PD in a "3T" structure is controlled by a voltage-controlled current source;

[0041] Figure 13A and Figure 13B Shows a PDD that includes a PS and circuitry operable to reduce the impact of dark current.

[0042] Figure 13C Shows a PDD that includes multiple PSs and circuitry operable to reduce the impact of dark current;

[0043] Figure 14 Shows an exemplary PDIV curve and possible operating voltages of the PDD;

[0044] Figure 15 Shows a control voltage generation circuit that is connected to multiple reference photosensitive sites;

[0045] Figure 16A and Figure 16B Shows multiple PDDs that include an array of multiple PSs and a reference circuit based on multiple PDs;

[0046] Figure 17 and Figure 18 Shows multiple PDDs, each of which includes a PS and circuitry operable to reduce the impact of dark current;

[0047] Figure 19 Illustrates a PDD that includes optical devices, a processor, and multiple additional components;

[0048] Figure 20 Is a flowchart that illustrates a method for compensating for dark current in a photodetector;

[0049] Figure 21 Is a flowchart that illustrates a method for compensating for dark current in a photodetector;

[0050] Figure 22 Is a flowchart that illustrates a method for testing a photodetector;

[0051] Figure 23 Illustrate an EO system according to some embodiments;

[0052] Figure 24 Illustrate an example of a method for generating image information based on data of a PDA;

[0053] Figure 25 and Figure 26 Respectively show a flowchart illustrating a method for generating a model for PDA operation at different frame exposure times and a graphical representation of performing the method on different frames of the same scene captured at different frame exposure times;

[0054] Figure 27 Is a flowchart illustrating an example of a method for generating multiple images based on different subsets of multiple PSs under different operating conditions;

[0055] Figure 28A and 28B Illustrate an EO system and multiple exemplary target objects;

[0056] Figure 29 Is a flowchart illustrating a method for generating image information based on data of a PDA.

[0057] It will be understood that, for simplicity and clarity of illustration, the various elements shown in the drawings are not necessarily drawn to scale. For example, for clarity, the dimensions of some elements may be enlarged relative to other elements. Additionally, where considered appropriate, numerous reference numerals may be repeated among the various drawings to indicate corresponding or similar elements. Detailed Description

[0058] In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the present disclosure. However, those skilled in the art will understand that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present disclosure.

[0059] In the illustrated drawings and description, the same reference numerals indicate those components common to different embodiments or configurations.

[0060] Unless otherwise specifically stated, it will be apparent from the following discussion that, throughout the specification discussion, it is understood that terms such as "processing", "calculating", "computing", "determining", "generating", "setting", "configuring", "selecting", "defining", etc. include the actions and / or processes of a computer that manipulate and / or transform data into other data, where the data is represented as physical quantities, such as various electronic quantities, and / or data representing the various physical objects.

[0061] The terms "computer", "processor", and "controller" should be broadly interpreted to cover any kind of electronic device having data processing capabilities, including by way of non-limiting examples: a personal computer, a server, a computing system, a communication device, a processor (such as a digital signal processor (DSP), a microcontroller, a field programmable gate array (FPGA), an application specific integrated circuit, etc.), any other electronic computing device, or any combination thereof.

[0062] Operations in accordance with the teachings herein can be performed by a computer specially constructed for the desired purpose or by a general-purpose computer specially configured for the desired purpose through a computer program stored in a computer-readable storage medium.

[0063] As used herein, the phrases "for example", "such as", "for instance", and their variants describe various non-limiting embodiments of the presently disclosed subject matter. References in the specification to "one case", "some cases", "other cases", or their variants mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the presently disclosed subject matter. Thus, the appearance of the phrases "one case", "some cases", "other cases", or their variants does not necessarily mean the same (s) embodiment.

[0064] It should be understood that, for clarity, certain features of the presently disclosed subject matter that are described in the context of multiple separate embodiments may also be provided in combination in a single embodiment. Conversely, for brevity, the various features of the presently disclosed subject matter that are described in the context of a single embodiment may also be provided separately or in any suitable sub-combination.

[0065] In various embodiments of the presently disclosed subject matter, one or more stages or steps illustrated in the figures may be performed in a different order and / or one or more groups of stages may be performed simultaneously, and vice versa. The figures illustrate a general schematic diagram of a system architecture according to an embodiment of the presently disclosed subject matter. Each module in the figures may be composed of any combination of software, hardware, and / or firmware that performs the various functions defined and explained herein. The various modules in the figures may be centralized in one location or dispersed in more than one location.

[0066] Any reference in the specification to a method should be applied mutatis mutandis to a system capable of performing the method and should be applied mutatis mutandis to a non-transitory computer-readable medium storing instructions that, when executed by a computer, cause the method to be performed.

[0067] Any reference in the specification to a system should be applied mutatis mutandis to a method capable of being performed by the system and should be applied mutatis mutandis to a non-transitory computer-readable medium storing instructions executable by the system.

[0068] Any reference in the specification to a non-transitory computer-readable medium or similar term should be applied mutatis mutandis to a system capable of executing the instructions stored in the non-transitory computer-readable medium and should be applied mutatis mutandis to a method executable by a computer that reads the instructions stored in the non-transitory computer-readable medium.

[0069] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The materials, methods, and examples provided herein are illustrative only and not intended to be limiting.

[0070] The implementation of the methods and systems of the present disclosure involves manual, automatic, or a combination thereof to perform or complete certain selected tasks or steps. Moreover, the actual instruments and devices according to the preferred embodiments of the methods and systems of the present disclosure can be implemented by hardware or by software on any operating system of any firmware or a combination thereof to implement several selected steps. For example: as hardware, several selected steps of the present disclosure can be implemented as a chip or a circuit. As software, several selected steps of the present disclosure can be implemented as multiple software instructions executed by a computer using any suitable operating system. In any case, several selected steps of the methods and systems of the present disclosure can be described as being performed by a data processor, such as a computing platform for executing multiple instructions.

[0071] Figure 1A , Figure 1B and Figure 1C are schematic block diagrams respectively illustrating multiple active SWIR imaging systems 100, 100', and 100" according to multiple examples of the currently disclosed subject matter.

[0072] As used herein, an "active" imaging system is operable to detect light reaching the system from its field of view (FOV), detect it by an imaging receiver including multiple PDs, and process the multiple detection signals to provide one or more images of the field of view or a portion thereof. The term "image" means a digital representation of a scene detected by the imaging system, and the imaging system stores a color value of each element (pixel) in the image, and each pixel color represents light reaching the imaging system from different parts of the field of view (such as a 0.02° by 0.02° portion of the FOV, depending on the receiver optics). It should be noted that optionally, the imaging system can also be operable to generate other representations of the many objects or light in the FOV (such as a depth map, 3D model, polygon mesh), but the term "image" means a two-dimensional (2D) image without depth data.

[0073] System 100 includes an illumination source (IS) 102, and the illumination source (IS) is operable to emit multiple radiation pulses in the SWIR band towards one or more targets 104, causing the reflected radiation from the object to be reflected back in the direction of system 100. In Figure 1AIn it, the outgoing illumination is labeled 106, and the illumination reflected toward the system 100 is labeled 108. Many parts of the emitted radiation may also be reflected, deflected, or absorbed by the target in other directions. The term "target" means any object in the FOV of the imaging sensor, such as solid, liquid, flexible, and rigid objects. Some non-limiting examples of such objects include vehicles, roads, people, animals, plants, buildings, electronic devices, clouds, microscopic samples, articles in manufacturing, etc. Any suitable type of illumination source 102 can be used, such as one or more lasers, one or more light-emitting diodes (LEDs), one or more flash lamps, any combination of the above, etc. As discussed in more detail below, the illumination source 102 can optionally include one or more active lasers, or one or more P-QS lasers.

[0074] The system 100 also includes at least one imaging receiver (or simply "receiver") 110, and the imaging receiver 110 includes a plurality of germanium (Ge) PDs operable to detect the reflected SWIR radiation. The receiver generates an electrical signal for each of the plurality of germanium PDs, and the electrical signal represents the amount of SWIR light impinging within its detectable spectral range. The amount includes the amount of pulsed SWIR radiation reflected from the target, and may also include: additional SWIR light (such as arriving from the sun or from an external light source).

[0075] The term "germanium PD (Ge PD)" refers to any PD in which photoinduced electron excitation (subsequently detectable as a photocurrent) occurs within the germanium, within a germanium alloy (such as SiGe), or at the interface between germanium (or germanium alloy) and another material (such as silicon, SiGe). Specifically, the term "germanium PD" refers to both pure germanium PDs and also applies to germanium-silicon PDs. When germanium PDs containing germanium and silicon are used, different concentrations of geranium can be used. For example: the relative portion of germanium in the germanium PD (whether alloyed with silicon or adjacent to it) can be in the range of 5% to 99%. For example: the relative portion of germanium among the plurality of germanium PDs can be between 15% and 40%. It should be noted that materials other than silicon can also be part of the germanium PD, such as aluminum, nickel, silicide, or any other suitable material. In some implementations of the present disclosure, the plurality of germanium PDs can be pure germanium PDs (including more than 99.0% germanium).

[0076] It should be noted that the receiver can be implemented as a PDA fabricated on a single chip. Any of the PD arrays discussed throughout this disclosure can be used as the receiver 110. The germanium PDs can be arranged in any suitable configuration, such as a rectangular matrix (rows and columns of germanium PDs), honeycomb tiling, or even an irregular structure. Preferably, the number of germanium PDs in the receiver allows for the generation of a high-resolution image. For example, the number of PDs can be on the order of 1 megapixel, 10 megapixels, or more.

[0077] In some embodiments, the receiver 110 has the following specifications:

[0078] a. HFOV (Horizontal Field of View) [m]: 60

[0079] b. WD (Working Distance) [m]: 150

[0080] c. Pixel Size [um]: 10

[0081] d. Resolution (on target) [mm]: 58

[0082] e. Pixel # [H]: 1,050

[0083] f. Pixel # [V]: 1112

[0084] g. Aspect Ratio: 3:1

[0085] h. Viewing Angle [rad]: 0.4

[0086] i. Reflectivity of Target [%]: 10%

[0087] j. Collection (assuming a target reflectivity of 100% and assuming Lambertian reflectivity, the ratio of photons collected to photons emitted): 3e -9 。

[0088] In addition to the impact SWIR light as described above, the electrical signals generated by each of the plurality of germanium PDs also represent:

[0089] a. Readout noise, which is random and its amplitude is independent (or substantially independent) of the integration time. Examples of such noise include Nyquist Johnson noise (also known as thermal noise or kTC noise). In addition to the statistical component, the readout process can also introduce a DC component into the signal, but the term "readout noise" refers to the random component of the signal introduced by the readout process.

[0090] b. Dark current noise is random and accumulates over the integration time (i.e., it depends on the integration time). In addition to the statistical component, the dark current also introduces a DC component (which may or may not be eliminated, e.g., as discussed with respect to Figures 12A to 22 ), into the signal, but the term "dark current noise" pertains to the random component of the signal that is accumulated by the dark current over the integration time.

[0091] Some germanium PDs, especially certain PDs that combine germanium with another material (such as silicon), are characterized by a relatively high level of dark current. For example, the dark current of multiple germanium PDs may be greater than 50 μA / cm 2 (related to the surface area of the PD), and even greater (e.g., greater than 100 μA / cm 2 , greater than 200 μA / cm 2 or greater than 500 μA / cm 2 ). Depending on the surface area of the PD, such levels of dark current can be converted to 50 picoamperes (pA) or higher per germanium PD (e.g., more than 100 pA per germanium PD, more than 200 pA per germanium PD, more than 500 pA per germanium PD, or more than 2 nA per germanium PD). It should be noted that multiple PDs of different sizes can be used, such as approximately 10 mm 2 , approximately 50 mm 2 , approximately 100 mm 2 , approximately 500 mm 2 . It should be noted that when the multiple germanium PDs are subject to different levels of non - zero bias, the multiple germanium PDs may generate dark currents of different amplitudes (which causes a dark current of, for example, more than 50 picoamperes on each of the multiple germanium PDs).

[0092] System 100 also includes a controller 112 and an image processor 114. The controller 112 controls the operation of the receiver 110 (and optionally also controls the illumination source (IS) 102 and / or other components). Thus, the controller 112 is configured to control the activation of the receiver 110 within a relatively short integration time, thereby limiting the impact of the accumulation of dark current noise on the signal quality. For example, the controller 112 can operate to control the activation of the receiver 110 within an integration time during which the accumulated dark current noise does not exceed the readout noise of the irrelevant integration time.

[0093] Now refer to Figure 2 , Figure 2is an exemplary graph illustrating the relative magnitudes of noise power after different durations at multiple integration times for various examples of the subject matter according to the present disclosure. For a given laser pulse energy, the signal-to-noise ratio (SNR) is primarily determined by the noise level, which includes the dark current noise (the noise of the dark photocurrent) and the thermal noise (also known as kTC noise). As Figure 2 shown in the exemplary graph of, depending on the integration time of the germanium-based receiver 110, either the dark current noise or the thermal noise dominates in affecting the SNR of the electrical signal of the PD. Since the controller 112 limits the activation time of the germanium photodetector within a relatively short time (within the range designated as "A" in Figure 2 ), not many electrons from the dark current noise are collected, and thus the SNR is improved and is thus mainly affected by the thermal noise. For a longer receiver integration time, when affecting the SNR of the receiver, the noise from the dark current of the germanium photodetector will exceed the thermal noise, causing a degradation in receiver performance. It should be noted that Figure 2 the graph of is merely illustrative, and the accumulation of dark current noise over time generally increases with the square root of time (alternatively, consider the y-axis to be plotted on a matching non-linear polynomial scale). Also, at zero integration time (in a situation where the accumulated dark current noise is zero), the multiple axes do not cross each other.

[0094] Returning to system 100, it should be noted that the controller 112 can control the activation of the receiver 110 for a shorter integration time (such as an integration time during which the accumulated dark current noise does not exceed half or a quarter of the readout noise). It should be noted that unless specifically required, limiting the integration time to a very low level will limit the number of light-induced signals that can be detected and will make the SNR with respect to the thermal noise worse. It should be noted that the thermal noise level in multiple readout circuits suitable for reading multiple noisy signals (which requires collecting a relatively high signal level) will introduce non-negligible readout noise, which may severely reduce the SNR.

[0095] In some implementations, the controller 112 can apply a slightly longer integration time (such as an integration time during which the accumulated dark current noise does not exceed twice the readout noise or 1.5 times the readout noise).

[0096] Exemplary embodiments disclosed herein relate to systems and methods for high SNR active SWIR imaging using multiple receivers including multiple germanium-based PDs. The main advantage of germanium receiver technology compared to indium gallium arsenide technology is its compatibility with CMOS process flows, allowing the receivers to be fabricated as part of a CMOS production line. For example, multiple germanium PDs can be integrated into the CMOS process flow by growing multiple Ge epitaxial layers on a silicon (Si) substrate, such as using Si photonics. Thus, many germanium PDs are also more cost-effective than equivalent indium gallium arsenide (InGaAs) PDs.

[0097] To utilize multiple germanium PDs, an exemplary system disclosed herein is adapted to overcome the limitation of the relatively high dark current of multiple germanium diodes, typically in the range of about 50 μA / cm^2. By using active imaging with a combination of short capture times and multiple high-power laser pulses, the dark current problem can be overcome.

[0098] Compared to indium gallium arsenide (InGaAs) technology, the use of multiple germanium PDs - particularly but not limited to those fabricated using CMOS process flows - is a much cheaper solution for uncooled SWIR imaging. Unlike many prior art imaging systems, the active imaging system 100 includes a pulsed illumination source having a short illumination duration (such as less than 1 μS, such as 1 to 1000 μS) and a high peak power. Despite the disadvantages of such pulsed light sources (such as uneven illumination, more complex readout circuits that may introduce higher levels of readout noise) and the disadvantages of shorter integration times (such as being unable to capture a wide range of distances in a single acquisition cycle). In the following description, several ways are discussed to overcome these disadvantages to provide effective imaging systems.

[0099] Now refer to Figure 1B and Figure 1C , which schematically illustrate several other SWIR imaging systems numbered 100' and 100'' according to some embodiments. Like system 100, system 100' includes an active illumination source 102A and a receiver 110. In some embodiments, the imaging systems 100, 100' and 100'' also include a controller 112 and an image processor 114. In some embodiments, the processing of the output of the receiver 110 can be performed by the image processor 114 and additionally or alternatively by an external image processor (not shown). The multiple imaging systems 100' and 100'' can be variants of the imaging system 100. Any component or function discussed with respect to system 100 can be implemented in any of systems 100' and 100'', and vice versa.

[0100] The controller 112 is a computing device. In some embodiments, many of the functions of the controller 112 are provided within the illumination source 102 and the receiver 110, and the controller 112 is not required as a separate component. In some embodiments, the imaging systems 100' and 100" are controlled by the combined action of the controller 112, the illumination source 102, and the receiver 110. Additionally or alternatively, in some embodiments, the imaging systems 100' and 100" can be controlled by an external controller such as a vehicle electronic control unit (ECU) 120 (which may belong to a vehicle in which the imaging system has been installed).

[0101] The illumination source 102 is configured to emit an optical pulse 106 in the infrared (IR) region of the electromagnetic spectrum. More specifically, the optical pulse 106 is in the SWIR spectral band and includes wavelengths in a range of approximately 1.3 μm to 3.0 μm.

[0102] In some embodiments, such as shown in Figure 1B , the illumination source (now labeled 102A) is an active Q-switch laser (or "active Q-switched" laser) that includes a gain medium 122, a pump 124, multiple mirrors (not shown), and an active QS element 126A. In some embodiments, the QS element 126A is a modulator. After the gain medium 122 is pumped electronically or optically by the pump 124, an optical pulse is released by actively triggering the QS element 126A.

[0103] In some embodiments, such as shown in Figure 1C , the illumination source 102P is a P-QS laser that includes a gain medium 122, a pump 124, multiple mirrors (not shown), and a SA 126P. After a "passive QS" optical pulse is released, the SA 126P allows the laser cavity to store optical energy (from the gain medium 122 pumped by the pump 124) until a saturation level is reached in the SA 126P. To detect the release of the passive QS pulse, a QS pulse photodetector 128 is coupled to the illumination source 102P. In some embodiments, the QS pulse photodetector 128 is a germanium PD. The signal from the QS pulse photodetector 128 is used to trigger the receiving process in the receiver 110 such that the receiver 110 will be activated after a time period suitable for the distance of the target 104 to be imaged. The time period is derived as further described in reference to Figure 3B , Figure 3C , Figure 4B and Figure 4C as further described.

[0104] In some embodiments, the laser pulse duration from the illumination source 102 ranges from 100 ps to 1 microsecond. In some embodiments, the laser pulse energy ranges from 10 microjoules to 100 millijoules. In some embodiments, the laser pulse period is on the order of 100 microseconds. In some embodiments, the laser pulse period ranges from 1 microsecond to 100 milliseconds.

[0105] The gain medium 122 is provided in the form of a crystal or alternatively in the form of a ceramic. Non-limiting examples of the plurality of materials that can be used for the gain medium 122 include: Nd:YAG, Nd:YVO4, Nd:YLF, Nd:Glass, Nd:GdVO4, Nd:GGG, Nd:KGW, Nd:KYW, Nd:YALO, Nd:YAP, Nd:LSB, Nd:S-FAP, Nd:Cr:GSGG, Nd:Cr:YSGG, Nd:YSAG, Nd:Y2O3, Nd:Sc2O3, Er:Glass, Er:YAG, and so on. In some embodiments, the plurality of doping levels of the gain medium can be changed based on the need for a specific gain. Non-limiting examples of the plurality of SA 126P include: Co2+:MgAl2O4, Co2+:Spinel, Co2+:ZnSe and other cobalt-doped crystals, V3+:YAG, doped glass, quantum dots, semiconductor saturable absorber mirror (SESAM), Cr4+YAG SA, and the like. The many additional ways in which the P-QS laser 102P can be implemented are discussed with reference to Figure 6 Figs. 11, and any variations discussed with respect to a laser 600 can also be applied mutatis mutandis to the illumination source 102P.

[0106] Regarding the illumination source 102, it should be noted that pulsed lasers with sufficient power and sufficiently short pulses are more difficult and expensive to obtain than non-pulsed illumination, especially when eye-safe SWIR radiation based on solar absorption is required.

[0107] The receiver 110 may include: one or more germanium PDs 118 and receiver optics 116. In some embodiments, the receiver 110 includes a 2D array of a plurality of germanium PDs 118. The receiver 110 is selected to be sensitive to infrared radiation that at least includes the wavelengths emitted by the illumination source 102, such that the receiver can form imagery of the illuminated target 104 from the reflected radiation 108.

[0108] The receiver optics 116 can include: one or more optical elements, such as mirrors or lenses, which are arranged to collect, concentrate, and optionally filter the reflected electromagnetic radiation 108 and focus the electromagnetic radiation onto a focal plane of the receiver 110.

[0109] The receiver 110 generates a plurality of electrical signals in response to the electromagnetic radiation detected by one or more germanium PDs 118 representative of the imagery of the illumination scene. The plurality of signals detected by the receiver 110 can be transmitted to an internal image processor 114 or an external image processor (not shown) for processing into a SWIR image of the target 104. In some embodiments, the receiver 110 is activated multiple times to create “multiple time slices”, each time slice covering a specific distance range. In some embodiments, the image processor 114 combines these slices to create a single image with greater visual depth, such as that presented by Gruber, Tobias, et al., “Gated2depth: Real-Time Dense LiDAR from Gated Images”, arXiv preprint arXiv:1902.04997 (2019), which is hereby incorporated by reference in its entirety.

[0110] In the automotive field, the target 104 of the images within the field of view (FOV) of the receiver 110 generated by the multiple imaging systems 100’ or 100” can be processed to provide various driver assistance and safety functions, such as: forward collision warning (FCW), lane departure warning (LDW), traffic sign recognition (TSR), and detection of relevant entities such as pedestrians or oncoming vehicles. The generated images can also be displayed to the driver, for example, on a head-up display (HUD) projected onto the vehicle windshield. Additionally or alternatively, the multiple imaging systems 100’ or 100” can interface with a vehicle ECU 120 to provide images or videos to enable autonomous driving under low light levels or adverse visibility conditions.

[0111] In many active imaging scenarios, a light source such as a laser is combined with an array of multiple optical receivers. Since the germanium PD operates in the SWIR band, high-power optical pulses are feasible without exceeding eye-safety regulations. For implementations in automotive scenarios, a typical pulse length is ~100 nanoseconds (ns), although in some embodiments, longer pulse durations of up to about 1 microsecond can also be expected. Considering eye safety, a peak pulse power of ~300 kilowatts (KW) is allowed, but current laser diodes cannot actually reach this level. Therefore, in the present system, the high-power pulse is generated by a QS laser. In some embodiments, the laser is a P-QS laser to further reduce costs. In some embodiments, the laser is an active QS.

[0112] As used herein, the term "target" means any imaged entity, object, area, or scene. Non-limiting examples of targets in many automotive applications include vehicles, pedestrians, physical obstacles, or other objects.

[0113] According to some embodiments, an active imaging system includes: an illumination source for emitting a radiation pulse towards a target, thereby causing reflection of the radiation from the target, wherein the illumination source includes a QS laser; and a receiver including one or more germanium PDs for receiving the reflected radiation. In some embodiments, the illumination source operates in the SWIR spectral band.

[0114] In some embodiments, the QS laser is an active QS laser. In some embodiments, the QS laser is a P-QS laser. In some embodiments, the P-QS laser includes a SA. In some embodiments, the SA is selected from the group consisting of: Co2+:MgAl2O4, Co2+:spinel, Co2+:ZnSe, and other cobalt-doped crystals, V3+:YAG, doped glass, quantum dots, semiconductor saturable absorber mirrors (SESAM), and Cr4+YAG SA.

[0115] In some embodiments, the system further includes a QS pulse photodetector for detecting a radiation pulse emitted by the P-QS laser. In some embodiments, the receiver is configured to be activated at a time sufficient for the radiation pulse to travel to a target and return to the receiver. In some embodiments, the receiver is activated during an integration time within which the dark current power of the germanium PD does not exceed the kTC noise power of the germanium PD.

[0116] In some embodiments, the receiver generates a plurality of electrical signals in response to the reflected radiation received by the plurality of germanium PDs, wherein the plurality of electrical signals represent an image of the target irradiated by the radiation pulse. In some embodiments, the plurality of electrical signals are processed by an internal image processor or an external image processor into an image of the target. In some embodiments, the image of the target is processed to provide one or more of forward collision warning, lane departure warning, traffic sign recognition, and detection of pedestrians or oncoming vehicles.

[0117] According to many additional embodiments, a method for performing active imaging includes the steps of: emitting a light pulse through an illumination source, the illumination source including an active QS laser; and after a time sufficient for the light pulse to travel to a target and return to the QS laser, activating a receiver, the receiver including one or more germanium PDs, for a limited time period to receive a reflected light pulse reflected from the target. In some embodiments, the illumination source operates in the short-wave infrared (SWIR) spectral band. In some embodiments, the limited time period is equal to an integration time during which the dark current power of the germanium PDs does not exceed the kTC noise power of the germanium PDs.

[0118] In some embodiments, the receiver generates the plurality of electrical signals in response to the reflected light pulse received by the plurality of germanium PDs, wherein the plurality of electrical signals represent an image of the target irradiated by the light pulse. In some embodiments, the plurality of electrical signals are processed by an internal image processor or an external image processor into an image of the target. In some embodiments, the image of the target is processed to provide one or more of forward collision warning, lane departure warning, traffic sign recognition, and detection of pedestrians or oncoming vehicles.

[0119] According to many additional embodiments, a method for performing active imaging includes the steps of: pumping a P-QS laser, the P-QS laser including a SA, to cause the emission of a light pulse when the SA is saturated; detecting the emission of the light pulse through a QS pulse photodetector; and based on the detected emission of the light pulse, after a time sufficient for the light pulse to travel to a target and return to the QS laser, activating a receiver, the receiver including one or more germanium PDs, for a limited time period to receive the reflected light pulse. In some embodiments, the QS laser operates in the short-wave infrared (SWIR) spectral band.

[0120] In some embodiments, the SA is selected from Co2+:MgAl2O4, Co2+:spinel, Co2+:ZnSe, other cobalt-doped crystals, V3+:YAG, doped glass, quantum dots, semiconductor saturable absorber mirror (SESAM), and Cr4+YAG SA. In some embodiments, the limited time period is equal to an integration time during which the dark current power of the germanium PD does not exceed the kTC noise power of the germanium PD.

[0121] In some embodiments, the receiver generates a plurality of electrical signals in response to the reflected light pulses received by the plurality of germanium PDs, where the plurality of electrical signals represent an image of the target illuminated by the light pulses. In some embodiments, the plurality of electrical signals are processed into an image of the target by one of an internal image processor or an external image processor. In some embodiments, the image of the target is processed to provide one or more of forward collision warning, lane departure warning, traffic sign recognition, and detection of pedestrians or oncoming vehicles.

[0122] Exemplary embodiments relate to a system and method for high SNR active SWIR imaging using a plurality of germanium-based PDs. In some embodiments, the imaging system is a gated imaging system. In some embodiments, the pulsed illumination source is an active or P-QS laser.

[0123] Now refer to Figure 3A , Figure 3B and Figure 3C , which respectively show a flowchart and a plurality of schematic diagrams of an operating method of an active SWIR imaging system according to some embodiments. The process 300 shown in Figure 3A is based on as referred to Figure 1BThe described system 100'. In step 302, the pump 124 of the illumination source 102A is activated to pump the gain medium 122. In step 304, the active QS element 126A emits an optical pulse in the direction of a target 104, which is located at a distance D. In step 306, at time = T, the optical pulse impinges on the target 104 and generates reflected radiation that returns towards the system 100' and the receiver 110. In step 308, after waiting for a time = T2, the receiver 110 is activated to receive the reflected radiation. The return propagation delay T2 consists of the flight time of the pulse from the illumination source 102A to the target 104 plus the flight time of the optical signal reflected from the target 104. Thus, for a target 104 located at a distance "D" from the illumination source 102A and the receiver 110, T2 is known. The activation period Δt of the receiver 110 is determined based on the desired depth of view (DoV). The DoV is given by 2DoV = c * Δt, where c is the speed of light. A typical Δt of 100 ns provides a depth of view of 15 meters. In step 310, the reflected radiation is received by the receiver 110 over a period of Δt. The received data from the receiver 110 is processed by the image processor 114 (or an external image processor) to generate a received image. Process 300 can be repeated N times in each frame, where a frame is defined as the dataset transmitted from the receiver 110 to the image processor 114 (or an external image processor). In some embodiments, N is between 1 and 10,000.

[0124] Now refer to Figure 4A , Figure 4B and Figure 4C respectively show a flowchart and multiple schematic diagrams of an exemplary operating method of an active SWIR imaging system according to some embodiments. A process 400 shown in FIG. 4 is based on as referred to Figure 1C"System 100 as described". In step 402, the pump 124 of the illumination source 102P is activated to pump the gain medium 122 and saturate the SA 126P. In step 404, after reaching a saturation level, the SA 126P releases an optical pulse in the direction of a target 430 located at a distance D. In step 406, the QS pulsed photodetector 128 detects the released optical pulse. In step 408, at time = T, the optical pulse impinges on the target 430 and generates reflected radiation that returns towards the system 100" and the receiver 110. In step 410, after a time = T2 following the waiting for a released optical pulse detected by the QS pulsed photodetector 128, the receiver 110 is activated to receive the reflected radiation. The return propagation delay T2 includes the time of flight of the pulse from the illumination source 102P to the target 430 plus the time of flight of the optical signal reflected from the target 430. Thus, for a target 430 located at a distance "D" from the illumination source 102P and the receiver 110, T2 is known. The activation period of the Δt is determined according to the desired depth of view (DoV). In step 412, the receiver 110 receives the reflected radiation for a period of Δt. The received data from the receiver 110 is processed by the image processor 114 (or by an external image processor) to generate a received image. Process 400 can be repeated N times in each frame. In some embodiments, N is between 1 and 10,000.

[0125] Referring to all imaging systems 100, 100', and 100", it should be noted that any one of those imaging systems can include: a readout circuit for reading out a cumulative charge collected by each germanium PD after the integration time to provide the detection signal of the corresponding PD. Thus, unlike LIDARs or other depth sensors, the readout process can be performed after the oscillation of the integration time and thus after the signal has been irreversibly summed from a wide range of distances.

[0126] Referring to all imaging systems 100, 100', and 100", optionally, the receiver 110 outputs a set of detection signals representing the charge accumulated by each of the plurality of germanium PDs during the integration time, where the set of detection signals represents the imagery of the target irradiated by at least one SWIR radiation pulse.

[0127] Referring to all imaging systems 100, 100', and 100", the imaging systems may optionally include at least one diffractive optical element (DOE), which is operable to improve the illumination uniformity of the light of the pulsed illumination source before the light is emitted towards the target. As described above, a high peak power pulsed light source 102 may emit a non-uniform illumination distribution over different parts of the FOV. The DOE (not illustrated) may improve the illumination uniformity to generate multiple high-quality images of the FOV. It should be noted that equivalent illumination uniformity is generally not required in many lidar systems and other depth sensors, and thus, for reasons such as cost, system complexity, system volume, etc., they may not include many DOE elements. For example: in many LIDAR systems, as long as the entire FOV receives sufficient illumination (above a threshold that allows detecting a target at a minimum required distance), it does not matter whether some regions in the FOV receive more illumination density than other parts of the FOV. The DOE of the system 100, if implemented, may be used, for example, to reduce many speckle effects. It should be noted that the imaging systems 100, 100', and 100" may also include: other types of optical devices for guiding light from the light source 102 to the FOV, such as lenses, mirrors, prisms, waveguides, etc.

[0128] Referring to all imaging systems 100, 100', and 100", the controller 112 may optionally be operated to activate the receiver 110 to sequentially acquire a series of gated images, each gated image representing the detection signals of different germanium PDs within a different distance range, and an image processor is operable to combine the series of images into a single two-dimensional image. For example: a first image may acquire light from the imaging sensor between 0 and 50 meters (m), a second image may acquire light from the imaging sensor between 50 and 100 meters, a third image may acquire light from the imaging sensor between 100 and 125 meters, and the image processor 114 may combine multiple 2D images into a single 2D image. In this way, each distance range is captured with accumulated dark current noise, which is still less than the read noise introduced by the readout circuit, at the cost of using more light pulses and more computations. The color value (such as a grayscale value) of each pixel of the final image may be determined according to a function (such as a maximum value or a weighted average of all values) of the respective pixels in the multiple gated images.

[0129] All imaging systems 100, 100', and 100", where the imaging system can be an uncooled germanium-based SWIR imaging system, operable at a distance of more than 50 meters (m) to detect a 1 m x 1 m target with a 20% SWIR reflectance (within the relevant spectral range).

[0130] Referring to all imaging systems 100, 100', and 100", the pulsed illumination source 102 can be a QS laser, which is operable to emit eye-safe laser pulses having a pulse energy between 10 millijoules (mJ) and 100 millijoules. Although not necessary, the illumination wavelength can be selected to match a solar absorption band (e.g., the illumination wavelength can be between 1.3 micrometers (μm) and 1.4 μm).

[0131] Referring to all imaging systems 100, 100', and 100", the output signal of each germanium PD for image generation can represent a single scalar for each PD. Referring to all imaging systems 100, 100', and 100", each PD can output an accumulated signal that represents a wide range of distances. For example: some, most, or all of the germanium PDs of the receiver 110 can output multiple detection signals that represent the light reflected from 20 m, 40 m, and 60 m to the respective PDs.

[0132] Compared with many known technology systems, another distinguishing feature of the imaging systems 100, 100', and 100" is that the pulsed illumination is not used to freeze the rapid movement of objects in the wild (e.g., different from photographic flash illumination), and is also used for static scenes. Compared with many known technology systems, another distinguishing feature of the imaging systems 100, 100', and 100" is that, compared with external noise, the gating of the image is not mainly used to avoid internal noise in the system, which is a nuisance for some known technologies (e.g., sunlight).

[0133] It should be noted that any of the components, features, operating modes, system architectures, and internal relationships discussed above for the systems 100, 100', and 100" can be implemented in any of the EO systems discussed below, such as the systems 700, 1300, 1300', 1600, 1600', 1700, 1800, 1900, 2300, and 3600, if necessary.

[0134] Figure 5FIG. 500 is a flow chart illustrating a method for generating SWIR images of objects in a FOV of an EO system according to various examples of the present disclosure. Referring to the examples described with respect to the previous figures, method 500 may be performed by any of the imaging systems 100, 100', and 100". It should be noted that method 500 may also be implemented by any active imaging system described below (such as systems 700, 1300, 1300', 1600, 1600', 1700, 1800, 1900, 2300, and 3600).

[0135] Method 500 begins with a step (or "stage") 510 of emitting at least one illumination pulse towards the FOV, thereby causing SWIR radiation to be reflected from at least one target. Hereinafter, "step" and "stage" may be used interchangeably. Optionally, the one or more pulses may be high peak power pulses. For example, multiple illumination pulses may need to be used to achieve an overall higher level of illumination compared to a single pulse. Referring to the examples of the figures, step 510 may optionally be performed by controller 112.

[0136] A step 520 includes initiating continuous signal acquisition triggered by an imaging receiver, the imaging receiver including a plurality of germanium PDs (in the sense discussed above with respect to receiver 110), the receiver 110 being operable to detect the reflected SWIR radiation. The continuous signal acquisition of step 520 means that the charge is collected continuously and irreversibly (i.e., it is not possible to know what level of charge was collected at any intermediate time), and not in small incremental amounts. The triggering of step 520 may be performed before step 510 (e.g., if the detection array requires an acceleration time), simultaneously with step 510, or after step 510 ends (e.g., starting detection at a non-zero distance from the system). Referring to the examples of the figures, step 520 may optionally be performed by controller 112.

[0137] Step 530 begins after triggering step 520 and includes collecting for each of the plurality of germanium PDs, as a result of the triggering, at least the charge caused by the SWIR reflected radiation impinging on the respective germanium PD, a dark current greater than 50 μA / cm 2 of dark current, dark current noise related to the integration time, and readout noise unrelated to the integration time. Referring to the examples of the figures, step 530 may optionally be performed by receiver 110.

[0138] Step 540 includes triggering a stop to the collection of the charge when the amount of charge collected due to dark current noise is still lower than the amount of charge collected due to the readout noise for the accumulated idle time. The integration time is the duration from step 530 until the stop in step 540. Referring to the example of the accompanying drawings, step 540 may optionally be performed by the controller 112.

[0139] A step 560 is performed after the end of step 540, and step 560 includes generating an image of the FOV based on the charge levels collected by each of the plurality of germanium PDs. As previously described with respect to the imaging systems 100, 100', and 100", the image generated in step 560 is a 2D image without depth information. Referring to the example of the accompanying drawings, step 560 may optionally be performed by the imaging processor 114.

[0140] Optionally, the stop of collection as a result of step 540 may be followed by an optional step 550 of reading, by a readout circuit, a signal related to the amount of charge collected by each of the plurality of germanium PDs, amplifying the read signal, and providing the amplified signal (optionally, after further processing) to an image processor that performs the generation of the image as in step 560. Referring to the example of the accompanying drawings, step 550 may optionally be performed by the readout circuit (not illustrated above but may be equivalent to any of the readout circuits discussed below, such as a readout circuit 1610, 2318, and 3630). It should be noted that step 550 is optional because other suitable methods of reading out the detection results from the plurality of germanium PSs may be implemented.

[0141] Optionally, the signal output by each of the plurality of germanium PDs is a scalar representing the amount of light reflected from 20 meters, the amount of light reflected from 40 meters, and the amount of light reflected from 60 meters.

[0142] Optionally, the generation in step 560 may include: generating the image based on a scalar value read for each of the plurality of germanium PDs. Optionally, the emission in step 510 may include: increasing the illumination uniformity of the pulsed laser illumination by causing the pulsed laser illumination (by one or more lasers) to pass through at least one diffractive optical element (DOE) and emitting the attenuated light into the FOV. Optionally, the dark current is greater than 50 picoamperes per germanium PD. Optionally, the plurality of germanium PDs are a plurality of silicon-germanium PDs (Si-Ge PDs), each silicon-germanium PD including silicon and germanium. Optionally, the emission is performed by at least one active QS laser. Optionally, the emission is performed by at least one P-QS laser. Optionally, the collection is performed when the receiver operates at a temperature higher than 30 °C, and the image of the FOV is processed to detect a plurality of vehicles and a plurality of pedestrians in a plurality of ranges between 50 meters and 150 meters. Optionally, the emission includes emitting a plurality of illumination pulses having a pulse energy between 10 millijoules and 100 millijoules at a distance of less than 1 meter into an unprotected eye of a person without damaging the eye.

[0143] As previously described with respect to the many active imaging systems 100, 100', and 100", several gated images may be combined into a single image. Optionally, method 500 may include: repeating the sequence of emitting, triggering, collecting, and ceasing multiple times; triggering the acquisition at different times from the light emission in each sequence. In each sequence, method 500 may include: reading a detection value from the receiver, the detection value being for each of the plurality of germanium PDs corresponding to different distance ranges greater than 2 meters (such as 2.1 meters, 5 meters, 10 meters, 25 meters, 50 meters, 100 meters). In such a case, the generation of the image in step 560 includes generating a single two-dimensional image based on the plurality of detection values read from different germanium PDs in different sequences. It should be noted that since only a few images are taken, the plurality of gated images are not sparse (i.e., in all or most of the gated images, there are detection values for many pixels). It should also be noted that the plurality of gated images may have overlapping distance ranges. For example: a first image may represent a distance range of 0 to 60 meters, a second image may represent a distance range of 50 to 100 meters, and a third image may represent a distance range of 90 to 120 meters.

[0144] Figures 6 to 11C Demonstrate that many SWIR electro-optical (EO) systems and many P-QS lasers can be used in such systems, as well as many methods for the operation and manufacture of such lasers.

[0145] Figure 10 FIG. 3 is a schematic functional block diagram illustrating an example of a SWIR optical system 700 according to various examples of the present disclosure. The system 700 includes at least a P-QS laser 600, but may also include various additional components as shown, such as a sensor 702 operable to sense reflected light from the FOV of the system 700, particularly the reflected illumination of the laser 600 reflected from various external objects 910. Figure 10 As shown, it may include various additional components, such as a sensor 702 operable to sense reflected light from the FOV of the system 700, particularly the reflected illumination of the laser 600 reflected from various external objects 910.

[0146] Referring to other examples, the sensor 702 may be implemented as an imaging receiver, PDA, or various photodetector devices discussed in the present disclosure, such as various components 110, 1300, 1300', 1600, 1600', 1700, 1800, 1900, 2302, and 3610.

[0147] A processor 710 operable to process the various sensing results of the sensor 702. The output of the processing may be an image of the FOV, a depth model of the FOV, a spectral analysis of one or more portions of the FOV, information on various identified objects in the FOV, light statistics on the FOV, or any other type of output. Referring to other examples, the processor 710 may be implemented as any of the various processors discussed in the present disclosure, such as various processors 114, 1908, 2304, and 3620.

[0148] A controller 712 operable to control the activities of the laser 600 and / or the processor 710. For example, the controller 712 may include controlling the timing, synchronization, and other operating parameters of the processor 710 and / or the laser 600. Referring to other examples, the controller 712 may be implemented as any of the various other controllers discussed in the present disclosure, such as controllers 112, 1338, 2314, and 3640.

[0149] Optionally, the system 700 may include a SWIR PDA 706 sensitive to the wavelength of the laser. Thus, the SWIR optical system may be used as an active SWIR camera, SWIR time-of-flight (ToF) sensor, SWIR light detection and ranging (LIDAR) sensor, etc. The ToF sensor may be sensitive to the wavelength of the laser. Optionally, the PDA may be a CMOS-based PDA sensitive to the various SWIR frequencies emitted by the laser 600, such as a CMOS-based PDA designed and manufactured by TriEye LTD of Tel Aviv, Israel.

[0150] Optionally, system 700 may include: a processor 710 for processing detection data from the SWIR PDA (or any other photosensitive sensor of system 700). For example: the processor may process the detection information to provide a SWIR image of a field of view (FOV) of system 700 to detect various objects in the FOV, and the like. Optionally, the SWIR optical system may include: a time-of-flight (ToF) SWIR sensor and a controller, the time-of-flight (ToF) SWIR sensor being sensitive to the wavelength of the laser, the controller being operable to synchronize the operations of the ToF SWIR sensor and the P-QS SWIR laser to detect a distance of at least one object in the field of view of the SWIR optical system. Optionally, system 700 may include: a controller 712, the controller 712 being operable to control one or more aspects of the operation of laser 600 or various other components of the system such as a photodetector array (such as a focal plane array, FPA). For example: some parameters of the laser may be controlled by the controller, including timing, duration, intensity, focusing, and the like. Although not necessary, the controller may control the operation of the laser based on the detection results of the PDA (directly, or based on the processing of the processor). Optionally, the controller may be operable to control the laser pump or other types of light sources to affect various activation parameters of the laser. Optionally, the controller may be operable to dynamically change the pulse repetition rate. Optionally, the controller may be operable to control the dynamic modification of the light shaping optics, for example: to improve the signal-to-noise ratio (SNR) in specific regions in the field of view. Optionally, the controller may be operable to control the illumination module to dynamically change the pulse energy and / or duration (such as in the same manner as possible for many other P-QS lasers, such as changing the focusing of the pumped laser, etc.).

[0151] Further and optionally, system 700 may include: temperature control (such as passive temperature control, active temperature control) for generally controlling the temperature of the laser or one or more of its components (such as the pump diode). Such temperature control may include: for example, a thermoelectric cooler (TEC), a fan, a heat sink, a resistive heater under the pump diode, and so on.

[0152] Further and optionally, system 700 may include: another laser used to bleach at least one of GM 602 and SA 604. Optionally, system 700 may include: an internal photosensitive detector (such as one or more PDs, like PDA 706), the internal photosensitive detector being operable to measure a time for generating a pulse by laser 600 (such as the PD as described above). In such a case, controller 712 is operable to issue a trigger signal to PDA 706 (or other type of camera or sensor 702) based on the timing information obtained from internal photosensitive detector 706, and PDA 706 detects the reflection of the light of the laser from a plurality of objects in the field of view of system 700.

[0153] The main industry that requires a large number of lasers within the above spectral range (1.3 to 1.5 μm) is the electronics industry for optical data storage, which has reduced the cost of the diode lasers to a few dollars per watt per device or even lower. However, these lasers are not suitable for other industries, such as the automotive industry, which require lasers to have a relatively high peak power and beam brightness and will be used under harsh environmental conditions.

[0154] It should be noted that there is no scientific consensus regarding the wavelength range considered to be part of the SWIR spectrum. However, for the purposes of this disclosure, the SWIR spectrum includes electromagnetic radiation whose wavelength is greater than the wavelength of the visible spectrum and which includes at least the spectral range between 1300 and 1500 nm.

[0155] Although not limited to this use, one or more P-QS lasers 600 may be used as the illumination source 102 of any one of imaging systems 100, 100' and 100". Laser 600 may be used in any other EO system within the SWIR range that requires pulsed illumination, such as a plurality of lidars, a plurality of spectrometers, a plurality of communication systems, and the like. It should be noted that the proposed lasers 600 and the methods for manufacturing such lasers allow for mass production of lasers operating within the SWIR spectrum at a relatively low production cost.

[0156] P-QS laser 600 at least includes a crystalline gain medium 602 (hereinafter the gain medium is also referred to as "GM"), a crystal SA 604, and an optical cavity 606. The above crystalline materials are confined in the optical cavity 606 to allow light to propagate in the gain medium 602 to enhance the tendency to generate a laser beam 612 (such as in Figure 8(shown in). The optical cavity is also well-known as the terms "optical resonator" and "resonating cavity", and the optical cavity includes a high-reflectivity mirror 608 (also known as a "high reflector") and an output coupler 610. Discussed below are unique and novel combinations of several different types of crystalline materials, and multiple manufacturing techniques are used to fabricate lasers, thereby allowing for the mass production of many lasers in the SWIR spectral range at reasonable prices. For the sake of brevity of this disclosure, general details known in the art about P-QS lasers are not provided herein, but these details can be readily obtained from a variety of sources. As is known in the art, the saturable absorber of the laser serves as the Q-switch of the laser. The term "crystalline material" broadly includes any material in single-crystal form or polycrystalline form.

[0157] The dimensions of the coupled crystal gain medium and crystal SA can depend on the purpose of designing a particular P-QS laser 600. In a non-limiting example, a combined length of the SA and the GM is between 5 and 15 millimeters. In a non-limiting example, the combined length of the SA and the GM is between 2 and 40 millimeters. In a non-limiting example, a diameter of the combination of the SA and the GM (such as if it is a cylinder, or confined within a fictional such cylinder) is between 2 and 5 millimeters. In a non-limiting example, a diameter of the combination of the SA and the GM is between 0.5 and 10 millimeters.

[0158] The P-QS laser 600 includes a gain medium crystalline material (GMC) that is rigidly connected to a SA crystalline material (SAC). The rigid coupling can be achieved in any of the ways known in the art, such as using adhesives, diffusion bonding, composite crystal bonding, growing one on top of the other, and the like. However, as described below, a rigidly connected crystalline material in the form of a ceramic can be achieved using simple and inexpensive methods. It should be noted that the GMC and SAC materials can be rigidly connected directly to each other, but can optionally be rigidly connected to each other via an intermediate body (such as another crystal). In some embodiments, both the gain medium and the SA can be implemented on a single-piece crystalline material, by doping different dopants (such as those discussed below with respect to the SAC material and GMC) in different parts of the single-piece crystalline material, or by co-doping the single-piece crystalline material with two dopants (such as co-doped with N 3+ and V3+ Alternatively, the gain medium may be grown on a single crystal saturable absorbing substrate (e.g., using liquid phase epitaxy, LPE). It should be noted that the separate GMC material and SA crystalline material, as widely discussed in the following disclosure, and the monolithic ceramic crystalline material doped with both dopants may also be used in any of the following implementations.

[0159] Figure 7A , Figure 7B and Figure 7C 6 is a schematic functional block diagram illustrating examples of a P-QS laser 600 in accordance with the presently disclosed subject matter. Figure 7A In FIG. 6 , the two dopants are implemented on two portions of the common crystalline material 614 (acting as both GM and SA), while in Figure 7B In the embodiment, the two dopants are implemented interchangeably on a common volume of common crystalline material 614 (in the illustrated case - the entirety of the common crystal). Alternatively, the GM and the SA may be implemented on a single piece of crystalline material doped with neodymium and at least one other material. Alternatively (e.g. Figure 7C As shown in FIG. 4 ), any one or both of the output coupler 610 and the high reflectivity mirror 608 can be directly glued to one of the multiple crystalline materials (such as the GM or the SA, or a crystal combining the two).

[0160] At least one of the SAC and the GMC is a ceramic crystalline material, which is a related crystalline material (e.g., doped yttrium aluminum garnet, YAG, doped with vanadium) in a ceramic form (e.g., a polycrystalline form). Crystalline materials having one (especially two) ceramic forms allow for higher quantity and lower cost production. For example: instead of growing a separate single crystal material in a slow and limited process, a polycrystalline material can be manufactured by powder sintering (i.e., compacting and possibly heating a powder to form a solid mass), low temperature sintering, vacuum sintering, and the like. One of the crystalline materials (SAC or GMC) can be sintered on top of the other, thereby eliminating the need for complex and expensive processing procedures such as polishing, diffusion bonding, or surface activated bonding. Optionally, at least one of the GMC and the SAC is polycrystalline. Optionally, both the GMC and the SAC are polycrystalline.

[0161] The combinations of the crystalline materials of the GMC and the SAC mentioned above can be made, and such combinations may include:

[0162] a. The GMC is neodymium-doped yttrium aluminum garnet (Nd:YAG) in ceramic form, and the SAC is (a) vanadium trivalent-doped yttrium aluminum garnet (V 3+ :YAG) in ceramic form or (b) a cobalt-doped crystalline material. Optionally, the cobalt-doped crystalline material may be a divalent cobalt-doped crystalline material. In those alternatives, both the Nd:YAG and the SAC selected from the above group are in ceramic form. A cobalt-doped crystalline material is a crystalline material doped with cobalt. Many examples include cobalt-doped spinel (Co: cobalt or Co 2+ :MgAl2O4), cobalt-doped zinc selenide (Co 2+ :ZnSe), cobalt-doped YAG (Co 2+ :YAG). Although not necessarily so, in this option, the high-reflectivity mirror and the SA may optionally be rigidly connected to the gain medium and the SA such that the P-QS laser is a monolithic microchip P-QS laser (such as shown in Figure 8 and Figure 10 ).

[0163] b. The GMC is neodymium-doped yttrium aluminum garnet (Nd:YAG) in ceramic form, and the SAC is a non-ceramic SAC selected from a group of doped ceramic materials consisting of: (a) vanadium trivalent-doped yttrium aluminum garnet (V 3+ :YAG) and (b) cobalt-doped crystalline materials. Optionally, the cobalt-doped crystalline material may be a divalent cobalt-doped crystalline material. In such a case, the high-reflectivity mirror 608 and the output coupler 610 are rigidly connected to the gain medium and the SA such that the P-QS laser 600 is a monolithic microchip P-QS laser.

[0164] c. The GMC is a neodymium-doped rare earth element crystalline material in ceramic form, and the SAC is a ceramic crystalline material selected from a group of doped crystalline materials consisting of: (a) vanadium trivalent-doped yttrium aluminum garnet (V 3+ :YAG) and (b) many cobalt-doped crystalline materials. Optionally, the cobalt-doped crystalline material may be a divalent cobalt-doped crystalline material. Although not necessary, in this option, the high-reflectivity mirror 608 and the output coupler 610 may optionally be rigidly connected to the gain medium and the SA such that the P-QS laser 600 is a monolithic microchip P-QS laser.

[0165] It should be noted that in any implementation, a doped crystalline material can be doped with more than one dopant. For example, the SAC can be doped with the primary dopant disclosed above and at least one other doping material (e.g., in significantly lower amounts). A neodymium-doped rare-earth element crystalline material is a crystalline material whose unit cell contains a rare-earth element (one of a well-defined group of 15 chemical elements, including the 15 lanthanide elements as well as scandium and yttrium), and is doped with neodymium (e.g., triply ionized neodymium) which can replace the rare-earth element in a portion of the unit cell. Several non-limiting examples of neodymium-doped rare-earth element crystalline materials that can be used in the present disclosure are:

[0166] a. Nd:YAG (as described above), neodymium-doped potassium yttrium tungstate (Nd:KYW), neodymium-doped lithium yttrium fluoride (Nd:YLF), neodymium-doped yttrium orthovanadate (YVO4), in all of these the rare-earth element is neodymium, Nd;

[0167] b. Neodymium-doped gadolinium orthovanadate ((Nd:GdVO4), neodymium-doped gadolinium gallium garnet (Nd:GGG), neodymium-doped potassium gadolinium tungstate (Nd:KGW), in all of these the rare-earth element is gadolinium, Gd;

[0168] c. Neodymium-doped lanthanum scandium borate (Nd:LSB), where the rare-earth element is scandium;

[0169] d. Other neodymium-doped rare-earth element crystalline materials can be used, where the rare-earth element can be yttrium, gadolinium, scandium or any other rare-earth element.

[0170] The following discussion applies to any optional combination of a number of GMCs and a number of SACs.

[0171] Optionally, the GMC is directly rigidly connected to the SAC. Alternatively, the GMC and the SAC can be indirectly connected (e.g., each of the SAC and GMC is connected via a group of one or more intermediate crystalline materials and / or via one or more other solid materials transparent to the relevant wavelength). Optionally, one or both of the SAC and the GMC are transparent to the relevant wavelength.

[0172] Optionally, the SAC can be cobalt-doped spinel (Co:MgAl2O4). Optionally, the SAC can be cobalt-doped YAG (Co:YAG). Optionally, this can enable cobalt and neodymium Nd to be co-doped on the same YAG. Optionally, the SAC can be cobalt-doped zinc selenide (Co:ZnSe). Optionally, the GMC can be a ceramic cobalt-doped crystalline material. 2+ :MgAl2O4). Optionally, the SAC can be cobalt-doped YAG (Co:YAG). Optionally, this can enable cobalt and neodymium Nd to be co-doped on the same YAG. Optionally, the SAC can be cobalt-doped zinc selenide (Co 2+ :ZnSe). Optionally, the GMC can be a ceramic cobalt-doped crystalline material.

[0173] Optionally, an initial transmittance (T0) of the SA is between 75% and 90%. Optionally, the initial transmittance of the SA is between 78% and 82%.

[0174] The wavelengths emitted by the laser depend on the materials used in its construction, in particular on the materials and dopants of the GMC and the SAC. Some examples of output wavelengths include wavelengths in the range of 1,300 nm and 1,500 nm. Some more specific examples include 1.32 μm or about 1.32 μm (such as 1.32 μm ± 3 nm), 1.34 μm or about 1.34 μm (such as 1.34 μm ± 3 nm), 1.44 μm or about 1.44 μm (such as 1.44 μm ± 3 nm). A corresponding imager sensitive to one or more of these optical frequency ranges may be included in the SWIR optical system 700 (such as as Figure 10 shown).

[0175] Figure 8 and Figure 9 are schematic functional diagrams illustrating various examples of the SWIR optical system 700 in accordance with the presently disclosed subject matter. As demonstrated in these illustrations, in addition to the components discussed above, the laser 600 may include: various additional components, such as (but not limited to):

[0176] a. A light source such as a flash lamp 616 or a laser diode 618, where the laser diode 618 serves as a pump for the laser. Referring to the previous examples, the light source may serve as the pump 124.

[0177] b. Focusing optics 620 (such as a lens) for focusing light from the light source (such as 618) onto the optical axis of the laser 600.

[0178] c. A diffuser or other optics 622 for manipulating the laser beam 612 after it exits the optical cavity 606.

[0179] Optionally, the SWIR optical system 700 may include: optics 708 to spread the laser over a wider FOV to improve eye safety issues within the FOV. Optionally, the SWIR optical system 700 may include: optics 704 to collect the reflected laser from the FOV and direct it onto the sensor 702, for example: onto a photodetector array (PDA) 706, see Figure 10 . Optionally, the P-QS laser 600 is a diode-pumped solid-state laser (DPSSL).

[0180] Optionally, the P-QS laser 600 includes at least one diode pump light source and an optical device 620 for focusing the light of the diode pump light source into the optical resonator (optical cavity). Optionally, the light source is located on the optical axis (as an end pump). Optionally, the light source can be rigidly connected to the high reflectivity mirror 608 or the SA 604 such that the light source is part of a monolithic microchip P-QS laser. Optionally, the light source of the laser can include: one or more vertical cavity surface emitting laser (VCSEL) arrays. Optionally, the P-QS laser 600 includes at least one VCSEL array and an optical device for focusing the light of the VCSEL array into the optical resonator. The wavelength emitted by the light source (such as the laser pump) may depend on the many crystalline materials and / or many dopants used in the laser. Some exemplary pumping wavelengths that can be emitted by the pump include: 808 nm or about 808 nm, 869 nm or about 869 nm, about nine hundred and some nm.

[0181] The power of the laser may depend on its intended use. For example: the laser output power can be between 1 W and 5 W. For example: the laser output power can be between 5 W and 15 W. For example: the laser output power can be between 15 W and 50 W. For example: the laser output power can be between 50 W and 200 W. For example: the laser output power can be higher than 200 W.

[0182] The QS laser 600 is a pulsed laser and can have different frequencies (repetition rates), different pulse energies, and different pulse durations, which can depend on the use for which it is designed. For example: A repetition rate of the laser can be between 10 Hz and 50 Hz. For example: A repetition rate of the laser can be between 50 Hz and 150 Hz. For example: A pulse energy of the laser can be between 0.1 mJ and 1 mJ. For example: A pulse energy of the laser can be between 1 mJ and 2 mJ. For example: A pulse energy of the laser can be between 2 mJ and 5 mJ. For example: A pulse energy of the laser can be higher than 5 mJ. For example: A pulse duration of the laser can be between 10 ns and 100 ns. For example: A pulse duration of the laser can be between 0.1 μs and 100 μs. For example: A pulse duration of the laser can be between 100 μs and 1 ms. The size of the laser can also vary, for example depending on the size of its components. For example: The size of the laser can be X1 by X2 by X3, where each dimension (X1, X2, and X3) is between 10 mm and 100 mm, between 20 and 200 mm, and so on. The output coupling mirror can be flat, curved, or slightly curved.

[0183] Optionally, in addition to the gain medium and the SA, the laser 600 can further include: undoped YAG for preventing heat accumulation in an absorption region of the gain medium. The undoped YAG can optionally be shaped as a cylinder (such as a concentric cylinder) surrounding the gain medium and the SA.

[0184] Figure 11A FIG. is a flowchart illustrating an example of a method 1100 according to the presently disclosed subject matter. The method 1100 is a method for manufacturing a plurality of components for a P-QS laser, such as but not limited to the P-QS laser 600 described above. Referring to the numerous examples set forth with respect to the previous figures, the P-QS laser can be the laser 600. It should be noted that any variations discussed with respect to the laser 600 or with respect to one of its components can also be implemented with respect to the plurality of components of the P-QS laser manufactured in the method 1100 or with respect to one of its corresponding components, and vice versa.

[0185] Method 1100 begins with step 1102 of inserting at least one first powder into a first mold, which is subsequently processed in method 1100 to produce a first crystalline material. The first crystalline material is used as the GM or the SA of the P-QS laser. In some implementations, the gain medium of the laser is first fabricated (e.g., by sintering), and then the SA is fabricated on top of the previously fabricated GM (e.g., by sintering). In other implementations, the SA of the laser is first fabricated, and then the GM is fabricated on top of the previously fabricated SA. In other implementations, the SA and the GM are fabricated independently of each other and are coupled to form a single rigid body. The coupling can be done as part of heating, sintering, or later.

[0186] Step 1104 of method 1100 includes inserting at least one second powder into a second mold, the at least one second powder being different from the at least one first powder. The at least one second powder is later processed in method 1100 to produce a second crystalline material. The second crystalline material is used as the GM or the SA of the P-QS laser (so that one of the SA and the GM is made of the first crystalline material and the other functionally is made of the second crystalline material).

[0187] The second mold may be different from the first mold. Alternatively, the second mold may be the same as the first mold. In such a case, the at least one second powder may be inserted, for example, on top of the at least one first powder (or if already made, on top of the first green compact), beside it, around it, and so on. The same mold (if implemented) of inserting the at least one second powder into the at least one first powder can be performed before processing the at least one first powder into a first green compact, before processing the at least one first powder into the post-first green compact, or at some time during processing the at least one first powder into the first green compact.

[0188] The first powder and / or the second powder may include crushed YAG (or any other of the aforementioned materials, such as spinel, MgAl2O4, ZnSe) and a doping material (such as N 3+ 、V 3+ , Co). The first powder and / or the second powder may include: a material for making YAG (or any other material mentioned above, such as spinel, MgAl2O4, ZnSe) and a doping material (such as N 3+ 、V 3+ 、Co).

[0189] Step 1106 is performed after step 1102 and includes compacting the at least one first powder in the first mold to produce a first green body. Step 1104 is performed after step 1108 and includes compacting at least one second powder in the second mold to produce a second green body. If the at least one first powder and the at least one second powder are inserted into the same mold in steps 1102 and 1104, the compaction of the plurality of powders can be performed simultaneously in steps 1106 and 1108 (such as pressing the at least one second powder, which in turn compresses the at least one first powder against the mold), but this is not necessary. For example: Step 1104 (and thus step 1108 is also performed) can optionally be performed after the compaction of step 1106.

[0190] Step 1110 includes heating the first green body to yield a first crystalline material. Step 1112 includes heating the second green body to yield a second crystalline material. In different embodiments, the heating of the first crystal can be performed before, simultaneously, partially simultaneously, or after each of steps 1106 and 1110.

[0191] Optionally, the heating of the first green body at step 1110 precedes the compaction of the at least one second powder (and possibly also the insertion) at step 1108 (and possibly also at step 1104). The first green body and the second green body can be heated separately (such as at different times, at different temperatures, for different durations). The first green body and the second green body can be heated together (such as in the same oven), or connected to each other during heating or not. The first green body and the second green body can be subjected to different heating regimes, which can share partial co-heating while being heated separately in other parts of the heating regime. For example: One or both of the first green body and the second green body can be heated separately from the other green body, and then the two green bodies can be heated together (such as after coupling, but not necessarily so). Optionally, the heating of the first green body and the heating of the second green body include simultaneously heating the first green body and the second green body in a single oven. It should be noted that, optionally, the coupling of step 1114 is a result of simultaneously heating the two green bodies in a single oven. It should be noted that, optionally, the coupling of step 1114 is accomplished by co-sintering the two green bodies after physically connecting them to each other.

[0192] Step 1114 includes coupling the second crystalline material to the first crystalline material. The coupling can be performed in any coupling manner known in the art, several non-limiting examples of which were discussed above with respect to the P-QS laser 600. It should be noted that the coupling can have several sub-steps, and in different embodiments, some of these sub-steps can be intertwined with different steps among steps 1106, 1108, 1110, and 1112 in different ways. The coupling results in a single rigid crystalline body including the GM and the SA.

[0193] It should be noted that method 1100 can include: a plurality of additional steps that are used in the manufacture of many crystals (especially in the manufacture of ceramic or non-ceramic polycrystalline crystal compounds of polycrystalline materials bonded to each other). A few non-limiting examples include powder preparation, binder burn-out, densification, annealing, polishing (if needed, as described below), and the like.

[0194] The GM (as described above, which can be the first crystalline material or the second crystalline material) of the P-QS laser in method 1100 is a neodymium-doped crystalline material. The SA (as described above, which can be the first crystalline material or the second crystalline material) of the P-QS laser in method 1100 is selected from a group of a plurality of crystalline materials consisting of: (a) a neodymium-doped crystalline material, and (b) a doped crystalline material selected from a group of a plurality of doped crystalline materials consisting of yttrium aluminum garnet doped with trivalent vanadium (V 3+ :YAG) and cobalt-doped crystalline materials. At least one of the GM and the SA is a ceramic crystalline material. Optionally, both the GM and the SA are ceramic crystalline materials. Optionally, at least one of the GM and the SA is a polycrystalline material. Optionally, both the GM and the SA are polycrystalline materials.

[0195] Although many additional steps of the manufacturing process can be carried out between different stages of method 1100, in at least some implementations, it is not necessary to polish the first material before bonding the second material during the sintering process.

[0196] Regarding the many combinations of crystalline materials from which the GMC and the SAC can be manufactured in method 1100, such many combinations can include:

[0197] 1. The GMC is a ceramic neodymium-doped yttrium aluminum garnet (Nd:YAG), and the SAC is (a) a ceramic trivalent vanadium-doped yttrium aluminum garnet (V 3+ :YAG), or (b) a cobalt-doped crystalline material. In this alternative, both the Nd:YAG and the SAC selected from the above group are in ceramic form. A cobalt-doped crystalline material is a crystalline material doped with cobalt. Many examples include cobalt-doped spinel (Co:Spinel or Co 2+ :MgAl2O4), cobalt-doped zinc selenide (Co 2+ :ZnSe). Although not necessary, the high reflectivity mirror and the output coupler in this option can optionally be rigidly connected to the GM and the SA such that the P-QS laser is a monolithic microchip P-QS laser.

[0198] 2. The GMC is a ceramic neodymium-doped yttrium aluminum garnet (Nd:YAG), and the SAC is a non-ceramic SAC selected from a group of doped ceramic materials consisting of: (a) trivalent vanadium-doped yttrium aluminum garnet (V 3+ :YAG) and (b) various cobalt-doped crystalline materials. In such a case, the high reflectivity mirror and the output coupler are rigidly connected to the GM and the SA such that the P-QS laser is a monolithic microchip P-QS laser.

[0199] 3. The GMC is a ceramic neodymium-doped rare earth element crystalline material, and the SAC is selected from a group of doped crystalline materials consisting of: (a) trivalent vanadium-doped yttrium aluminum garnet (V 3+ :YAG) and (b) various cobalt-doped crystalline materials. Although not necessary, the high reflectivity mirror and the output coupler in this option can optionally be rigidly connected to the GM and the SA such that the P-QS laser is a monolithic microchip P-QS laser.

[0200] Overall, referring to method 1100, it should be noted that one or both of the SAC and the GMC (and optionally one or more intermediate connecting crystalline materials, if any) are transparent to the relevant wavelength (such as SWIR radiation).

[0201] Figure 11B and Figure 11C include several conceptual timelines for performing method 1100 including many examples according to the presently disclosed subject matter. To simplify the drawings, it is assumed that the SA is a result of the processing of at least one first powder, and the gain medium is a result of the processing of at least one second powder. As described above, the roles can be interchanged.

[0202] Figure 12A An example of a PS numbered 1200 is schematically shown, including a photodetector (such as a PD) 1202 controlled by a voltage-controlled current source (VCCS) 1204. It should be noted that the voltage-controlled current source 1204 can optionally be external to the PS 1200 (such as if a single VCCS 1204 supplies current to multiple PSs). The VCCS 1204 is a dependent current source that delivers a current proportional to a control voltage (labeled as VCTRL in the figure). The many PSs and many PDDs disclosed in this disclosure may include: any suitable type of VCCS. Other (“additional”) components of the PS 1200 (not shown) are collectively represented by a general box 1206. When used for sensing, many PSs such as the PS 1200 and many photodetectors such as the photodetector 1202 may also be referred to hereinafter as “active” or “non-reference” many PSs / many photodetectors (different from the many PSs and many photodetectors for determining the input of the control voltage of the current source).

[0203] Figure 12B Another example of a PS numbered 1200’ is schematically shown, which is an example of the PS 1200. In the PS 1200’, the other component 1206 is in the form of a “3T” (three-transistor) structure. Any other suitable circuit can be used as the many additional components 1206.

[0204] The current source 1204 can be used to provide a current with the same magnitude but opposite direction to the dark current generated by the PD 1202, thereby eliminating the dark current (or at least reducing it). This will be particularly useful if the PD 1202 is characterized by a high dark current characteristic. In this way, the charge flowing from the PD to a capacitor (as described above, which can be provided by one or more capacitors, the parasitic capacitance of the PS, or a combination thereof), and the charge caused by the dark current can be canceled. In particular, providing a current with a magnitude substantially equal to the dark current by the current source 1204 means that the provided current will not cancel the actual electrical signal generated by the PD 1202 due to the detected light impact on the PD 1202.

[0205] Figure 13AA PDD 1300 is shown that includes circuitry that can controllably match the current emitted by current source 1204 with the dark current generated by PD 1202, even when the generated dark current is not constant (varies over time). It should be noted that the level of the dark current generated by PD 1202 can depend on different parameters such as the operating temperature and the bias voltage supplied to the PD (which can also change from time to time).

[0206] Reducing the effect of dark current within PS1200 by PDD 1300 (rather than at a later stage of signal processing, whether analog or digital) enables the use of a relatively small capacitance without saturating the capacitance or reducing its linearity in responding to the collected charge.

[0207] PDD 1300 includes a PS1200 and a reference PS1310. The PS1200 is used to detect impinging light, and the output of the reference PS1310 is used by additional circuitry (discussed below) to reduce or eliminate the effect of dark current in PS1200. Like PS1200 (and 1200’), the reference PS1310 includes a PD 1302, a VCCS1304, and optionally other circuitry (“other components”, collectively referred to as 1306). In some examples, the reference PS1310 of PDD 1300 can be the same as the PS1200 of PDD 1300. Optionally, any one or more components of PS1310 can be the same as a corresponding component of PS1200. For example: PD 1302 can be substantially the same as PD 1202. For example: VCCS1304 can be the same as VCCS1204. Optionally, any one or more components of PS1310 can be different from those of the PS1200s (such as PD, current source, additional circuitry). It should be noted that substantially the same components of PS1200 and PS1310 (such as PD, current source, additional circuitry) can be operated under different operating conditions. For example: different bias voltages can be supplied to the multiple PDs 1202 and 1302. For example: different components of the additional components 1206 and 1306 can be operated using different parameters or selectively connected / disconnected, even when their structures are substantially the same. For simplicity and clarity, the components of PS1310 are numbered as 1302 (for the PD), 1304 (for the VCCS), and 1306 (for the additional circuitry), but this does not imply that these components are different from components 1202, 1204, and 1206.

[0208] In some examples, the reference additional circuit 1306 may be omitted or disconnected so as not to affect the determination of the dark current. PD 1202 may operate under any one of the following conditions: reverse bias, forward bias, zero bias, or selectively between any two or three of the above biases (e.g., controlled by a controller such as controller 1338 discussed below). PD1302 may operate under any one of the following conditions: reverse bias, forward bias, zero bias, or selectively between any two or three of the above biases (e.g., controlled by a controller such as controller 1338 discussed below). A number of PDs 1202 and 1302 may operate at substantially the same bias voltages (e.g., approximately -5V, approximately 0V, approximately +0.7V), which is not necessary (e.g., when testing PDD 1300, as discussed in more detail below). Optionally, a single PS of PDD 1300 may sometimes operate as PS1200 (detecting light from a field of view (FOV) of PDD 1300), and sometimes operate as PS1310 (whose detected signal output is used to determine a control voltage for a VCCS of another PS 1200 of the PDD). Optionally, the roles of the "active" PS and the reference PS for detecting impact light may be exchanged. PDD 1300 further includes a control-voltage generating circuitry 1340, which at least includes an amplifier 1318 and a plurality of electrical connections to a plurality of PSs of PDD 1300. The amplifier 1318 has at least two inputs: a first input 1320 and a second input 1322. The first input 1320 of the amplifier 1318 is supplied with a first input voltage (V FI ), which may be directly controlled by a controller (implemented on PDD 1300, on an external system, or a combination thereof), or derived from other voltages in the system (which in turn may be controlled by the controller). The second input 1322 of the amplifier 1318 is connected to the cathode of PD 1302 (of the reference PS1310).

[0209] In a first usage example, PD 1202 is held at a first voltage (also referred to as "anode voltage", labeled as V A ) and a second voltage (also referred to as "cathode voltage", labeled as V C) a working bias voltage therebetween. The anode voltage can be directly controlled by the controller (implemented on the PDD 1300, on an external system, or a combination thereof), or derived from other voltages in the system (which can in turn be controlled by the controller). The cathode voltage can be directly controlled by the controller (implemented on the PDD 1300, on an external system, or a combination thereof), or derived from other voltages in the system (which can in turn be controlled by the controller). The anode voltage V A and the cathode voltage V C each can be held constant or not held constant over time. For example: the anode voltage V A can be provided by a constant source (e.g., via a pad, from an external controller). Depending on the implementation, the cathode voltage V C can be substantially constant or vary over time. For example: when a 3T structure is used in the PS1200, e.g., due to the operation of numerous additional components 1206 and / or the current from the PD 1202, V C varies over time. V C can optionally be determined / controlled / affected by numerous additional components 1206 (rather than by the reference circuit).

[0210] VCCS1204 is used to provide (feed) a current to the cathode terminal of the PD 1202 to cancel the dark current generated by the PD 1202. It should be noted that at other times, VCCS1204 can feed other currents to achieve other purposes (such as for calibrating or testing the PDD 1300). The level of the current generated by VCCS1204 is controlled in response to an output voltage of the amplifier 1318. The control voltage for controlling VCCS1204, labeled as V CTRL , can be the same as an output voltage of the amplifier 1318 (as shown in the figure). Alternatively, V CTRL can be derived from the output voltage of the amplifier 1318 (e.g., due to the resistance or impedance between the output of the amplifier 1318 and the VCCS1204).

[0211] To cancel (or at least reduce) the effect of the dark current of the PD 1202 on the output signal of the PS1200, the PDD 1300 can subject the PD 1302 to substantially the same bias voltage as that experienced by the PD 1202. For example: when the PD 1302 is substantially the same as the PD1202, subjecting the PD 1302 and the PD 1202 to the same bias voltage can be used. One way to supply the same bias voltage to the two PDs (1202 and 1302) is to supply the voltage V A(where the supplied voltage is labeled VRPA, and RPA stands for "reference PD anode"), and the voltage V is supplied to the cathode of PD 1302 C (where the applied voltage is labeled V RPC , and RPC stands for "reference PD cathode"). Another way to supply the same bias voltage is to supply V RPA = V A + ΔV to the anode of PD 1302, and supply V RPC = V C + ΔV to the cathode of PD 1302. Optionally, the anode voltage V A , the reference anode voltage V RPA or both can be provided by an external power supply (such as a printed circuit board (PCB) to which PDD 1300 is connected).

[0212] As described above, the first input 1320 of amplifier 1318 is supplied with a first input voltage V FI . The second input 1322 of amplifier 1318 is connected to the cathode of PD 1302. The operation of amplifier 1318 reduces the voltage difference between its two inputs (1320 and 1322), thereby causing the voltage on the second input 1322 to tend towards the same controlled voltage supplied to the first input (V FI ). Now refer to Figure 13B , where the dark current on PD 1302 (hereinafter labeled DC 参考 ) is represented by an arrow 1352 (the circuit shown in the figure is the same as the circuit of Figure 13A ). During the period when PD 1202 remains dark, the current on PD 1302 is equal to the dark current of PD 1202. PDD 1300 (or any system component connected to it or adjacent to it) may block light from reaching PD 1302, so it remains dark. The blocking can be done through a physical barrier (such as an opaque barrier), through optical devices (such as many steering lenses), through an electronic shutter, and the like. In the following description, it is assumed that all the current on PD 1302 is the dark current generated by PD 1302. Alternatively, if PD1302 is exposed to light (such as many low-level known stray lights in the system), a current source can be implemented to offset the known light-origin signal, or the first input voltage V FICan be modified to compensate (at least in part) for stray illumination. The barrier, optics, or other specialized component designed to direct light away from PD 1302 can be implemented at the wafer level (on the same wafer on which the PDD 1300 is fabricated), can be attached to that wafer (e.g., using an adhesive), can be rigidly attached to a housing in which the wafer is mounted, and the like.

[0213] Assume V FI is constant (or slowly varying), then the output of VCCS1304 (represented by arrow 1354) must be equal in magnitude to the dark current of PD 1302 (DC 参考 ), which means that VCCS1304 supplies charge carriers for the dark current consumption of PD 1302, thereby allowing the voltage to be maintained at VFI. Since the output of VCCS1304 is controlled by VCTRL in response to the output of amplifier 1318, amplifier 1318 is operated to output the required output such that VCTRL will control the output of VCCS 1304, which will be the same in magnitude as the dark current on PD 1302.

[0214] If PD 1202 is substantially the same as PD 1302 and VCCS1204 is substantially the same as VCCS1304, then the output of amplifier 1318 will also cause VCCS1204 to provide the same level of current (DC 参考 ) to the cathode of PD 1202. In such a case, in order for the output of VCCS1204 to cancel the dark current generated by PD 1202 (hereinafter labeled DC 有源PD ), it is required that both PD 1202 and PD 1302 generate a similar level of dark current. To subject the two PDs (1202 and 1302) to the same bias voltage (which will cause the two PDs to generate a substantially same level of dark current since both PDs are maintained under substantially the same conditions such as temperature), the voltage provided to the first input of amplifier 1318 is determined in response to the anode voltage and the cathode voltage of PD 1202 and the anode voltage of PD 1302. For example: If V A is equal to V RPA , then V C equal to V FI can be provided to the first input 1320. It should be noted that V C can change over time and is not necessarily determined by a controller (e.g., V Ccan be determined as a result of a number of additional components 1206). If PD 1202 is different from PD 1302 and / or if VCCS1204 is different from VCCS1304, the output of amplifier 1318 can be modified by matching a number of electrical components (not shown) between amplifier 1318 and VCCS1204 to provide a relevant control voltage to VCCS1204 (for example, if the dark current on PD 1202 is linearly related to the dark current on PD 1302, the output of amplifier 1318 can be modified according to the linear relationship). Another way to supply the same bias voltage is to supply V RPA = V A + ΔV to the anode of PD 1302, and supply V RPC = V C + ΔV to the cathode of PD 1302.

[0215] Figure 13C A photodetection device 1300' showing a number of examples according to the presently disclosed subject matter includes a plurality of PS1200. PDD 1300' includes all components of PDD 1300, as well as a number of additional PS 1200. Different PSs of PDD 1300' are substantially the same as each other (for example, all are part of a two-dimensional PDA), so the PDs 1302 of different PS1200 generate similar dark currents with each other. Therefore, the same control voltage V CTRL is supplied to all VCCS1204 of different PS1200 of PDD 1300', causing these VCCS1204 to cancel out (or at least reduce) the influence of the dark current generated by each PD 1202. Any option discussed above regarding PDD 1300 can be applied mutatis mutandis to PDD 1300'.

[0216] In some cases (for example, if V C is not constant and / or unknown), a first input voltage V FI can be provided (for example, by a controller), and the first input voltage V FI is selected to cause a dark current similar to that on PD 1202 on PD 1302.

[0217] Now refer to Figure 14 , which shows an exemplary PD I-V curve 1400 of a number of examples according to the presently disclosed subject matter. For ease of illustration, curve 1400 represents the I-V curves of both PD 1302 and PD 1202, which are assumed to be substantially the same for the purpose of this description and are subjected to the same anode voltage (that is, for the purpose of this description, V A = V RPA)。The I-V curve 1400 is relatively flat between voltages 1402 and 1404, which means that different bias voltages between 1402 and 1404 supplied to the associated PD will produce similar levels of dark current. If V C varies within a cathode voltage range, given a known V A , it means that the bias voltage on PD 1202 is restricted between voltages 1402 and 1404. Then supplying a VRPC will cause the bias voltage on PD 1302 to also be between voltages 1402 and 1404, which will cause VCCS1204 to output a current that is similar enough to DC 有源PD , even if PD 1202 and PD 1302 are subject to different bias voltages. In such a case, V RPC can be within the cathode voltage range (as shown by the equivalent voltage 1414) or outside of it (but still keep the bias voltage on PD 1302 between 1402 and 1404), as demonstrated by the equivalent voltage 1412. Modifications to other configurations, such as those discussed above, can be implemented analogously. It should be noted that for other reasons, different bias voltages can also be supplied to different PDs 1202 and 1302. For example: different bias voltages can be supplied as part of the testing or calibration of the PDA.

[0218] In real life, different PDs (or other components) of different PSs of a single PDD are not made exactly the same, and the operations of these PSs are not exactly the same as each other. In a PD array, many PDs may be somewhat different from each other, and the dark currents may vary (e.g., due to manufacturing differences, slight temperature differences, etc.).

[0219] Figure 15 A control voltage generation circuit 1340 is shown according to various examples of the present invention. The control voltage generation circuit 1340 is connected to a plurality of reference photosensitive sites 1310 (collectively 1500). Figure 15 The circuit (also referred to as the reference circuit 1500) can be used to determine a control voltage (labeled as V CTRL)。In particular, the reference circuit 1500 can be used to determine a control voltage based on data collected from multiple reference PS1310s that are somewhat different (such as a result of manufacturing inaccuracies, different operating conditions, etc.) to counteract (or limit) the effect of dark current in one or more PS1200s of a PDD. As mentioned before, the dark currents of many PDs, even if similar, may differ from each other. It should be noted that in some PD technologies, many PDs with the same intention may feature dark currents that differ by a factor of x1.5, x2, x4, or even more. The averaging mechanism discussed in this article even allows for compensation of such significant differences (such as in manufacturing). In the case where the amplifier 1318 is connected to multiple reference PS1310s to average the dark current levels of several PS1310s, keep such PS1310s in the dark, for example, using any of the mechanisms discussed above. The voltages of the different VCCS1304 supplied to various PS1310s are shorted so that all VCCS1304s receive substantially the same control voltage. The cathode voltages of the different reference PDs 1302 are shorted to different networks. Thus, although the currents in different reference PS1310s are slightly different from each other (due to the slight differences between the reference PS1310s), the averaged control voltage supplied to one or more PS1200s of each PDD (which may also be slightly different from each other and from the reference PS1310s) is accurate enough to counteract the effect of dark current on different PS1200s in a sufficiently uniform manner. Optionally, the output voltage of a single amplifier 1318 is supplied to all PS1200s and all reference PS1310s. Optionally, the selected PDs for the PDD have a flat I-V response (as mentioned above, for example, regarding Figure 14 ), such that the averaged control voltage discussed with respect to the reference circuit 1500 counteracts the dark current in different PS1200s to a very good extent. In Figure 16A and Figure 16BNumerous non-limiting examples of PDDs are provided, which include multiple reference PSs 1310, the average output signal of which is used to modify the multiple output signals of the multiple active PSs 1200 (e.g., to reduce the influence of the dark current of the output signal). Different configurations, geometries, and numerical ratios can be implemented between the multiple reference PSs 1310 and the multiple active PSs 1200 of a single PDD. For example: in a rectangular photodetection array including multiple PSs arranged in multiple rows and multiple columns, an entire row of PSs (e.g., 1,000 PSs) or several rows or columns of PSs can be used as the multiple reference PSs 1310 (and optionally kept in the dark), while the rest of the array receives the control signal based on the averaging of the outputs of those reference PS rows. This method of generating the control current significantly reduces the influence of the dark current by eliminating the average dark current and only leaving the PS-to-PS variations.

[0220] Figure 16A and Figure 16B illustrate multiple photodetection devices according to examples of the subject matter of the present disclosure, the multiple photodetection devices including an array of multiple PSs and a reference circuit based on multiple PDs. PDD 1600 ( Figure 16A shown) and PDD 1600' ( Figure 16B shown, which is a variant of PDD 1600) include all the components of PDD 1300, as well as multiple additional PSs 1200 and PSs 1310. Optionally, the different PSs of PDD 1600 (and PDD 1600' respectively) are substantially the same as each other. Any of the options discussed above regarding multiple PDDs 1300 and 1300' and regarding circuit 1500 can be analogously applied to PDDs 1600 and 1600'.

[0221] Figure 16AThere is shown a photodetector device 1600, the photodetector device 1600 including a photosensitive area 1602 (which is exposed to external light during the operation of the photodetector device 1600), an area 1604, and a control voltage generation circuit 1340. The photosensitive area 1602 includes a plurality (array) of PS1200. The area 1604 includes a plurality of reference PS1310 that are kept in the dark (at least during reference current measurement, optionally at all times). The control voltage generation circuit 1340 further includes a controller 1338. The controller 1338 can control the operation of the amplifier 1318, the voltage supplied to the amplifier 1318, and / or the operation of the plurality of reference PS1310. Optionally, the controller 1338 can also control the operations of the plurality of PS1200 and / or other components of the PDD 1600. The controller 1338 can control both the plurality of active PS 1200 and the plurality of reference PS1310 to operate under the same operating conditions (such as bias voltage, exposure time, managed readout regime). It should be noted that any function of the controller 1338 can be implemented by an external controller (such as being implemented on another processor of an EO system in which the PDD is installed, or by an auxiliary system such as a controller of an autonomous vehicle in which the PDD is installed). Optionally, the controller 1338 can be implemented as one or more processors, and the one or more processors are fabricated on the same wafer as other components of the PDD 1600 (such as the plurality of PS1200 and 1310, the amplifier 1318). Optionally, the controller 1338 can be implemented as one or more processors, and the one or more processors are located on a PCB connected to such a wafer. Other suitable controllers can also be implemented as the controller 1338.

[0222] Figure 16BAn optoelectronic detector device 1600’ is shown that illustrates many examples in accordance with the presently disclosed subject matter. The optoelectronic detector device 1600’ is similar to device 1600, but has a number of components arranged in a different geometry and the internal details of the many different PSs are not shown. Also illustrated is a readout circuit 1610 that is used to read the plurality of detection signals from the plurality of PSs 1200 and provide them for further processing (such as to reduce noise, for image processing), for storage, or for any other use. For example, the readout circuit 1610 may temporarily arrange the readout values of the different PSs 1200 sequentially (possibly after some processing by one or more processors of the PDD, not shown) before providing them for further processing, storage, or any other action. Optionally, the readout circuit 1610 may be implemented as one or more units that are fabricated on the same wafer as other components of the PDD 1600 (such as the plurality of PSs 1200 and 1310, amplifier 1318). Optionally, the readout circuit 1610 may be implemented as one or more units on a PCB that is connected to such a wafer. Other suitable readout circuits may also be implemented as the readout circuit 1610. It should be noted that a readout circuit such as the readout circuit 1610 may be implemented in any optoelectronic detection device discussed in the present disclosure (such as the plurality of PDDs 1300, 1700, 1800, and 1900). Prior to an optional digitization of the signals, many examples of analog signal processing may be performed in the PDD (such as by the readout circuit 1610 or one or more processors of the corresponding PDD), including: modifying the gain (amplification), offset, and combining (combining the plurality of output signals from two or more PSs). The digitization of the readout data may be implemented on the PDD or externally thereto.

[0223] Optionally, the PDD 1600 (or any other PDD disclosed in the present disclosure) may include: a sampling circuit that is used to sample the output voltage of the amplifier 1318 and / or the control voltage V CTRL(If different), and for maintaining said voltage level for at least one specified minimum time period. Such a sampling circuit can be located anywhere between the output of amplifier 1318 and one or more of the at least one VCCS 1204 (such as at location 1620). Any suitable sampling circuit can be used; for example: in some cases, an exemplary circuit can include: a plurality of "sample and hold" switches. Optionally, the sampling circuit can be used only at certain times and perform a direct real-time readout of the control voltage at other times. For example: when the amplitudes of the many dark currents in the system change slowly and when PS 1310 is shaded only part of the time, using a sampling circuit may be useful.

[0224] Figure 17 and Figure 18 show more photodetector devices according to examples of the presently disclosed subject matter. In the photodetector devices (such as 1300, 1300', 1600, 1600') described above, a voltage-controlled current source is used for the plurality of active PSs 1200 and the plurality of reference PSs 1310. A current source is an example of a voltage-controlled current circuit that can be used in the disclosed PDD. Another type of voltage-controlled current circuit that can be used is a voltage-controlled current-sink, the current absorbed by which is controlled in magnitude by the control voltage supplied to it. For example: a current absorber can be used, where the bias voltage on the plurality of PDs (1202, 1302) is in the opposite direction to the bias voltage demonstrated above. More generally, whenever a voltage-controlled current source (1204, 1304) is discussed above, this component can be replaced by a voltage-controlled current-sink (labeled 1704 and 1714 respectively). It should be noted that using a current absorber instead of a current source may require different types of components or circuits to be used in other parts of the corresponding PDD. For example: an amplifier 1318 used with the plurality of VCCSs 1204 and 1304 is different in power, size, etc. from an amplifier 1718 used with the plurality of voltage-controlled current-sinks 1704 and 1714. To distinguish the plurality of PSs including a plurality of voltage-controlled current-sinks instead of a plurality of VCCSs, the plurality of reference numerals 1200' and 1310' correspond to the plurality of PSs 1200 and 1300 discussed above.

[0225] In Figure 17In this case, a PDD 1700 includes a plurality of voltage-controlled current circuits, the plurality of voltage-controlled current circuits being a plurality of voltage-controlled current sinks (in both PS1200' and PS1310'), and a suitable amplifier 1718 is used in place of amplifier 1318. All of the variations discussed above regarding the various current sources apply equally to the various current sinks.

[0226] In Figure 18 this case, a PDD 1800 includes two types of voltage-controlled current circuits, voltage-controlled current sources 1204 and 1314 and voltage-controlled current sinks 1704 and 1714, as well as matching amplifiers 1318 and 1718. This can allow, for example, the plurality of PDs of PDD 1800 to be operated in forward or reverse bias. At least one switch (or other selection mechanism) can be used to select which reference circuit is activated / deactivated, the one based on the plurality of VCCSs or the one based on the plurality of voltage-controlled current sinks. Such a selection mechanism can be implemented, for example, to prevent two feedback regulators from working "against" each other (such as if operating at near-zero bias on the PD). Any of the options, explanations, or variations discussed above regarding any of the previously discussed PDDs (such as 1300, 1300', 1600, 1600') can be applied mutatis mutandis to the PDDs 1700 and 1800. In particular, the PDDs 1700 and 1800 can include: a plurality of PS1200' and / or a plurality of reference PS1310', similar to the discussion above (such as regarding Figure 15 , 16A and 16B).

[0227] It should be noted that in any of the plurality of photodetector devices discussed above, one or more of the PSs (such as the PSs of a photodetector array) can optionally be controllable to selectively act as a reference PS1310 (such as sometimes) or as a conventional PS1200 (such as other times). Such a PS may include the circuitry required to operate in both roles. For example: it can be used if the same PDD is used in different types of electro-optic systems. For example: one system may require averaging with high precision between 1,000 and 4,000 reference PS1310s, while another system may require a lower precision, which can be achieved by averaging between 1 and 1200 reference PS1310s. In another example, as described above, when the entire PDA is darkened and stored in a sample-and-hold circuit, averaging of the control voltages based on some (or even all) of the PSs can be performed, and all of the PSs can be used to detect FOV data using the determined control voltages in one or more subsequent frames.

[0228] It should be noted that, in the above discussion, for simplicity, it is assumed that the anode sides of all PDs on each PDA are connected to a known (and possibly controlled) voltage, and the connection of the plurality of detection signals and the plurality of VCCSs, and a plurality of additional circuits are implemented on the cathode side. It should be noted that, optionally, the plurality of PDs 1202 and 1302 can be connected in the opposite manner (where the readout is on the anode side, and so on).

[0229] Referring to all PDDs discussed above (such as 1300, 1600, 1700, 1800), it should be noted that the plurality of PSs, the readout circuit, the reference circuit, and other components described above (and any additional components that may be required) can be implemented on a single wafer or on more than one wafer, on one or more PCBs, or on another suitable type of circuit connected to the plurality of PSs, and so on.

[0230] Figure 19 A PDD 1900 is illustrated to exemplify a number of examples according to the presently disclosed subject matter. The PDD 1900 can implement any combination of features from one or more PDDs described above, and further includes a plurality of additional components. For example: The PDD 1900 can include any one or more of the following components:

[0231] a. At least one light source 1902, operable to emit light onto the FOV of the PDD 1900. Some of the light from the light source 1902 is reflected from the objects in the FOV and captured by the plurality of PSs 1200 in the photosensitive region 1602 (which is exposed to external light during the operation of the photodetector device 1900), and is used to generate an image or other model of the plurality of objects. Any suitable type of light source (such as pulsed, continuous, modulated LEDs, lasers) can be used. Optionally, the operation of the light source 1902 can be controlled by a controller (such as controller 1338).

[0232] b. A physical barrier 1904 for keeping the region 1604 of the detector array in the dark. The physical barrier 1904 can be part of the detector array or outside of it. The physical barrier 1904 can be fixed or movable (such as a movable shutter). It should be noted that other types of darkening mechanisms can also be used. Optionally, the physical barrier 1904 (or other darkening mechanisms) can darken different parts of the detection array at different times. Optionally, the operation of the barrier 1904, if variable, can be controlled by a controller (such as controller 1338).

[0233] c. Ignored photosensitive sites 1906. It should be noted that not all PSs of the PDA have to be used for detection (multiple PSs 1200) or as a reference (multiple PSs 1310). For example: Some PSs may be located in an area that is not completely darkened and not completely lit, and are thus ignored in the generation of the image (or other types of outputs generated in response to the multiple detection signals of multiple PSs 1200). Optionally, the PDD 1900 can ignore different PSs at different times.

[0234] d. At least one processor 1908 for processing the multiple detection signals output by the multiple PSs 1200. Such processing can include, for example, signal processing, image processing, spectral analysis, etc. Optionally, many processing results of the processor 1908 can be used to modify the operation of the controller 1338 (or another controller). Optionally, the controller 1338 and the processor 1908 can be implemented as a single processing unit. Optionally, the processing results of the processor 1908 can be provided to any one or more of the following: a tangible memory module 1910 for many external systems (such as a remote server or a vehicle computer of a vehicle in which the PDD 1900 is installed), for example, via a communication module 1912, a display 1914 for displaying images or other types of results (such as graphics, text results of a spectrometer), another type of output interface (such as a speaker, not shown), and so on. It should be noted that, optionally, the multiple signals from the multiple PSs 1310 can also be processed by the processor 1908, for example, to evaluate a condition of the PDD 1900 (such as operability, temperature).

[0235] e. A memory module for storing at least one of the multiple detection signals output by the multiple active PSs or by the readout circuit 1610 (if different), and the detection information generated by the processor 1908 by processing the multiple detection signals.

[0236] f. A power supply 1916 (such as a battery, an alternating current (AC) power adapter, a direct current (DC) power adapter). The power supply can supply power to the multiple PSs, the amplifier, or any other component of the PDD.

[0237] g. A hard casing 1918 (or any other type of structural support).

[0238] h. An optical device 1920 for guiding the light of the light source 1902 (if implemented) to the FOV and / or for guiding the light from the FOV to the plurality of active PSs 1200. Such an optical device may include, for example, a plurality of lenses, a plurality of mirrors (fixed or movable), a plurality of prisms, a plurality of filters, and the like.

[0239] As described above, the plurality of PDDs as described above can be used to match the control voltage that determines the current level provided by the at least one first voltage-controlled current circuit (VCCC) 1204, so as to account for the differences in the operating conditions of the PDDs, and the differences change the variations in the plurality of levels of the dark current generated by the at least one PD 1202. For example: For a PDD including a plurality of PSs 1200 and a plurality of PSs 1320: When the PDD operates at a first temperature, the control voltage generation circuit 1340 responds to the dark current of the plurality of reference PDs 1302 and provides a control voltage to the voltage-controlled current circuit to provide a current at a first level at the first temperature to reduce the influence of the dark currents of the active PDs 1202 on the output of the plurality of active PSs 1200; and when the PDD operates at a second temperature (higher than the first temperature), the control voltage generation circuit 1340 responds to the dark current of the plurality of reference PDs 1302 and provides a control voltage to the voltage-controlled current circuit for providing a current at a second level to reduce the influence of the dark currents of the plurality of active PDs 1202 on the output of the plurality of active PSs 1200, such that the second level is greater in magnitude than the first level.

[0240] Figure 20 It is a flowchart of a method 2000 for compensating for dark current in a photodetector according to examples of the subject matter of the present disclosure. The method 2000 is executed in a PDD that includes at least: (a) a plurality of active PSs, each active PS including at least one active PD; (b) at least one reference PS including a reference PD; (c) at least one first VCCC connected to one or more active PDs; (d) at least one reference VCCC connected to one or more reference PDs; and (e) a control voltage generation circuit connected to the active VCCC and the reference VCCC. For example: The method 2000 can be executed in any one of the plurality of PDDs 1300’, 1600, 1600’, 1700, and 1800 (the latter two include a plurality of active PSs in multiple implementations). It should be noted that the method 2000 may include: performing any action or function discussed above regarding any component of the various foregoing PDDs.

[0241] Method 2000 includes at least multiple stages (multiple stages) 2010 and 2020. Stage 2010 includes: generating a control voltage based on a level of dark current in the at least one reference PD, which, when provided to the at least one reference VCCC, causes the at least one reference VCCC to generate a current that reduces the effect of the dark current of the reference PD on an output of the reference PS. Stage 2020 includes providing the control voltage to the at least one first VCCC, thereby causing the at least one first VCCC to generate a current that reduces the effect of the dark current of the multiple active PDs on multiple outputs of the multiple active PSs. VCCC stands for "Voltage Controlled Current Circuit", and it can be implemented as a voltage-controlled current source or a voltage-controlled current sink.

[0242] Optionally, stage 2010 is implemented using an amplifier that is part of the control voltage generation circuit. In such a case, stage 2010 includes supplying a first input voltage to a first input of the amplifier when a second input of the amplifier is electrically connected between the reference PD and the reference voltage control current circuit. The amplifier can be used to continuously reduce a difference between an output of the reference voltage control circuit and the first input voltage, thereby generating the control voltage. Optionally, both the (multiple) first VCCCs and the (multiple) reference VCCCs are connected to an output of the amplifier.

[0243] In the case where the PDD includes multiple different reference PDs generating different levels of dark current, stage 2010 may include: generating a single control voltage based on an average of the different dark currents of the multiple reference PDs.

[0244] Method 2000 may include: preventing light from a field of view of the PDD from reaching the multiple reference PDs (such as using a physical barrier or steering optics).

[0245] Method 2000 may include: sampling the multiple outputs of the multiple active PSs after reducing the effects of the dark current, and generating an image based on the multiple sampled outputs.

[0246] Figure 21It is a flowchart showing a method for compensating dark current in a photodetector device according to various examples of the subject matter of the present disclosure. Method 2100 has two phases, which are executed in different temperature regimes; when the PDD operates at a first temperature (T1), a first phase group (2110 to 2116) is executed, and when the PDD operates at a second temperature (T2) higher than the first temperature, a second phase group (2120 to 2126) is executed. The degrees of the first temperature and the second temperature may vary in different implementations or in different instances of method 2100. For example: the temperature difference may be at least 5 °C; at least 10 °C; at least 20 °C; at least 40 °C; at least 100 °C, and so on. In particular, method 2100 may be effective at even smaller temperature differences (such as less than 1 °C). It should be noted that each of the first temperature and the second temperature may be implemented as a temperature range (such as spanning 0.1 °C; 1 °C; 5 °C or higher). Any temperature within the second temperature range is higher than any temperature within the first temperature range (such as according to the aforementioned ranges). Method 2100 may optionally be executed in any of the PDDs discussed above (1300, 1600, etc.). It should be noted that method 1020 may include: performing any of the actions or functions discussed above on any component of the various aforementioned PDDs, and the PDD of method 1020 may include: any combination of one or more of the multiple components discussed above with respect to any one or more of the aforementioned PDDs.

[0247] Refer to the multiple stages that are performed when the PDD operates at the first temperature (which can be a first temperature range): Stage 2110 includes determining a first control voltage based on the dark current of at least one reference PD of the PDD. Stage 2112 includes providing the first control voltage to a first VCCC, the first VCCC being coupled to at least one active PD of an active PS of the PDD, thereby causing the first VCCC to impose a first dark-current countering current in the active PS. Step 2114 includes generating a first detection current by the active PD in response to: (a) light impinging on the active PD that strikes an object in a field of view of the PDD, and (b) the dark current generated by the active PD. Stage 2116 includes outputting, by the active PS, a first detection signal in response to the first detection current and the first dark-current countering current, the first detection signal being smaller in magnitude than the first detection current, thereby compensating for the effect of the dark current on the first detection signal. Method 2100 may further include an optional stage 2118 of generating at least one first image of a FOV of the PDD based on multiple first detection signals from multiple PSs (and optionally all) of the PDD. Stage 2118 may be performed when the PDD is at the first temperature or in a subsequent stage.

[0248] Refer to the multiple stages that are performed when the PDD operates in the second temperature (which can be a second temperature range): Stage 2120 includes determining a second control voltage based on the dark current of at least one reference PD of the PDD. Step 2122 includes providing the second control voltage to the first VCCC, thereby causing the first VCCC to apply a second dark current rejection current in the active PS; Stage 2124 includes generating a second detection current by the active PD in response to: (a) the optical impact of the active PD from the object, and (b) the dark current generated by the active PD. Stage 2126 includes outputting, by the active PS, a second detection signal with an amplitude less than the second detection current in response to the second detection current and the second dark current rejection current, thereby compensating for the influence of the dark current on the second detection signal. The amplitude of the second dark current rejection current is greater than the amplitude of the first dark current rejection current, and may be by any ratio greater than one. For example: the ratio may be a factor of at least twice or significantly higher (such as on the order of one, two, three (or more) amplitudes). Method 2100 may further include an optional stage 2128 of generating at least one second image of a FOV of the PDD based on multiple second detection signals from multiple PSs (and optionally all) of the PDD. Stage 2128 may be performed when the PDD is at the second temperature or in a subsequent stage.

[0249] Optionally, a first level of radiation (L1) that impinges on the active PD from the object at a first time (t1) when the first dark current rejection current is generated is substantially equal to a second level of radiation (L2) that impinges on the active PD from the object at a second time (t2) when the second dark current rejection current is generated, wherein the amplitude of the second detection signal is substantially equal to the amplitude of the first detection signal. It should be noted that, optionally, the PDD according to the present disclosure can be used to detect multiple signal levels that are significantly lower than the dark currents of the multiple levels generated by its PDs at certain operating temperatures (such as on the order of one, two or more amplitudes). Therefore, method 2100 can be used to emit multiple output signals of multiple similar levels at two different temperatures, where the multiple dark currents are two or more orders of magnitude larger than the multiple detection signals and are significantly different from each other (such as by a factor of ×2, ×10)

[0250] Optionally, the determination of the first control voltage and the determination of the second control voltage are performed by a control voltage generation circuit including at least one amplifier having an input electrically connected between the reference PD and a reference voltage controlled current circuit coupled to the reference PD.

[0251] Optionally, method 2100 may further include supplying a first input voltage to another input of the amplifier, the level of the first input voltage being determined to correspond to a bias voltage on the active PD. Optionally, method 2100 may include supplying the first input voltage such that a bias voltage on the reference PD is substantially the same as a bias voltage on the active PD. Optionally, method 2100 may include, when the plurality of active PDs have a plurality of different dark currents, determining the first control voltage and the second control voltage based on different dark currents of a plurality of reference PDs of the PDD, wherein the providing of the first control voltage includes providing the same first control voltage to a plurality of first voltage controlled current circuits, each first voltage controlled current circuit being coupled to at least one of the plurality of active PDs of the PDD having different dark currents, and wherein the providing of the second control voltage includes providing the same second control voltage to the plurality of first voltage controlled current circuits.

[0252] Optionally, a plurality of different active PDs simultaneously generate a plurality of different levels of dark currents, and a plurality of different reference PDs simultaneously generate a plurality of different levels of dark currents, and the control voltage generation circuit provides a same control voltage to different active PDs based on an average of the plurality of different dark currents of the second PD. Optionally, method 2100 may include using dedicated optics to direct light from the field of view to the plurality of active PSs of the PDD; and preventing light from the field of view from reaching the plurality of reference PDs of the PDD.

[0253] Figure 22FIG. 2200 is a flow chart of a method for testing an optoelectronic detection device that illustrates various examples of the subject matter of the present disclosure. For example, the testing can be performed by any of the foregoing PDDs. That is, the same circuits and architectures that can be used to reduce the impact of dark current as described above can be used for additional purposes to test multiple detection paths of multiple different PSs in real time. Optionally, the testing can be completed while the PDD is in an operating mode (i.e., not in a test mode). In some implementations, some PSs can be tested while being exposed to ambient light from the FOV, even when multiple other PSs of the same PDD are capturing an actual image of the FOV (with or without compensation for dark current). Nevertheless, it should be noted that method 2200 can also optionally be implemented in multiple other types of PDDs. It should also be noted that method 2200 can also optionally be implemented using multiple circuits or architectures similar to the multiple circuits or architectures discussed above with respect to the foregoing multiple PDDs, but when the multiple PDs are not characterized by high dark current and reducing dark current is not required or performed. Method 2200 is described as being applied to a single PS, but it can be applied to some or all of the PSs of a PDD.

[0254] Stage 2210 of method 2200 includes providing a first voltage to a first input of an amplifier of a control voltage generation circuit, wherein the second input of the amplifier is connected to a reference PD and a second current circuit that supplies a current that is dominated at a level in response to an output voltage of the amplifier; thereby causing the amplifier to generate a first control voltage for a first current circuit of a PS of the PDD. Referring to the examples illustrated in the previous figures, the amplifier can be amplifier 1318 or amplifier 1718, and the PS can be PS1310 or PS1310'. Examples of multiple first voltages that can be provided to the first input are discussed below.

[0255] Stage 2220 of method 2200 includes reading a first output signal of the PS generated by the PS in response to the current generated by the first current circuit and the current generated by a PD of the PS.

[0256] Stage 2230 of method 2200 includes providing a second voltage different from the first input to the first input of the amplifier, thereby causing the amplifier to generate a second control voltage for the first current circuit. Examples of multiple such second voltages are discussed below.

[0257] Stage 2240 of method 2200 includes reading a second output signal of the PS generated by the PS in response to a current generated by the first current circuit and a current generated by a PD of the PS.

[0258] Stage 2250 of method 2200 includes determining a defect state of a detection path of the PDD based on the first output signal and the second output signal, the detection path including the PS and a readout circuit associated with the PS. Numerous examples of which types of defects can be detected when using multiple different combinations of a first voltage and a second voltage are discussed below.

[0259] A first example includes using at least one of the first voltage and the second voltage to attempt to saturate the PS (e.g., by providing a very high current to the capacitor of the PS through the VCCS, regardless of the actual detection level). Failure to saturate the PS (e.g., receiving a detection signal that is not white, possibly all black or halftone) indicates a problem with the associated PS or other components in its readout path (such as a PS amplifier, sampler, analog-to-digital converter). In such a case, the first voltage (for example) causes the amplifier to generate a control voltage, which causes the first current circuit to saturate the PS. In such a case, at stage 2250, the determination of the defect state may include: determining the detection path in which the PS is malfunctioning in response to determining that the first output signal is not saturated. In such a case, the second voltage may be a voltage that does not cause the PS to saturate (e.g., it causes the VCCS not to emit current, only compensating for the dark current to prevent current from being collected by the capacitor). Testing whether a PS detection path can be saturated can be implemented in real time.

[0260] When attempting to saturate one or more PSs to test the PDD, method 2200 may include: reading the first output signal while the PS is exposed to ambient light during a first detection frame of the PDD, wherein after previously determining that the detection path is operable, the determination of the fault state is performed in response to reading a saturated output signal in a second detection frame earlier than the first frame. For example: during an ongoing operation of the PDD (such as when capturing a video), if the saturation attempt fails, a PS may be determined to be defective or unavailable if it was successful at a previous time during the same operation. The test may be performed in a testing frame that is not part of the video, or for individual PSs for which saturated outputs are ignored (such as the pixel colors corresponding to these PSs may be completed from multiple adjacent pixels of the frame being tested), and these PSs are considered unavailable for the span of this frame).

[0261] A second example includes using at least one of the first voltage and the second voltage to attempt to consume the PS (such as by providing a very high opposite current to the capacitance of the PS through the VCCS, regardless of the actual detection level). Failure to consume the PS (such as receiving a detection signal that is not black, perhaps all white or halftone) indicates a problem with the associated PS or other components in its read path. In such a case, the second voltage (for example) causes the amplifier to generate a second control voltage, and the second control voltage causes the first current circuit to consume a detection signal caused by shock of the field of view light on the PS. In such a case, at stage 2250, the determination of the defective state may include: determining that the detection path is malfunctioning in response to determining that the second output signal is not consumed. In such a case, the first voltage may be a voltage that does not cause the PS to saturate (such as it causes the VCCS not to emit current, only compensating for the dark current, thus saturating the capacitance). Testing whether a PS detection path can be consumed (such as without darkening individual PSs) can be implemented in real time.

[0262] When attempting to consume one or more PSs to test the PDD, method 2200 may include reading the second output signal while the PS is exposed to ambient light during a third detection frame of the PDD, wherein after previously determining that the detection path is operable, the determination of the fault state is performed in response to reading a consumed output signal in a fourth detection frame earlier than the third frame.

[0263] Another example of usage method 2200 for testing a PS by supplying multiple control voltages includes supplying more than two voltages. For example, three or more different voltages can be provided to the first input of the amplifier at different times (such as in different frames). In such a case, stage 2250 may include determining the defective state of the detection path of the PDD based on the first output signal, the second output signal, and at least one other output signal corresponding to the third or more voltages supplied to the first input of the amplifier. For example, at different times (such as monotonically, where each voltage is greater than a previous voltage), three, four, or more different voltages can be supplied to the first input of the amplifier, and the multiple output signals of the same PS corresponding to different voltages can be tested to correspond to the multiple supplied voltages (such as the multiple output signals also increasing monotonically in amplitude).

[0264] An example of usage method 2200 for testing a part (or even all) of the PDD includes reading at least two output signals from each of the multiple PSs of the PDD in response to at least two different voltages of the amplifier provided to the corresponding PS, determining an operating state for at least one first detection path based on at least two output signals of at least one PS output associated with the corresponding first detection path, and determining a fault state for at least one second detection path based on the at least two output signals of at least one other PS output associated with the corresponding second detection path.

[0265] Optionally, when the PDD is shielded from ambient light and / or when using specified illumination (such as dedicated illumination of a known amplitude, etc.), method 2200 can be performed in combination with multiple specified test targets (such as black targets, white targets), but this is not necessary.

[0266] Optionally, stage 2250 can be replaced by an operation to determine an operating state of the detection path. For example, this can be used to calibrate multiple different PSs of the PDD to the same level. For example, when the PDD dims and there is no dedicated target or dedicated illumination, the same voltage can be supplied to the VCCSs of different PSs. The different output signals of different PSs can be compared with each other (at one or more different voltages supplied to the first input of the amplifier). Based on the comparison, multiple correction values can be assigned to different PS detection paths so that they will provide a similar output signal (simulated by the current included in the multiple VCCSs of different PSs) for a similar illumination level. For example, it can be determined that the output of PS A should be multiplied by 1.1 to output a calibrated output signal to PS B. For example, it can be determined that an incremental signal ΔS should be added to the output of PS C to output a calibrated output signal to PSD. Nonlinear correction can also be implemented.

[0267] Figure 23 An EO system 2300 is illustrated to exemplify a number of examples according to the presently disclosed subject matter. The EO system 2300 includes at least one PDA 2302 and at least one processor 2304 operable to process multiple detection signals from multiple PSs 2306 of the PDA. The EO system 2300 can be any type of EO system that uses a PDA for detection, such as a camera, a spectrometer, a LIDAR, and the like.

[0268] The at least one processor 2304 is operable and configured to process multiple detection signals output by multiple PSs 2306 of at least one PDA 2302. Such processing can include, for example, signal processing, image processing, spectral analysis, and the like. Optionally, the processing result of the processor 2304 can be provided to any one or more of the following: a tangible memory module 2308 (for storage or later retrieval), for an external system (such as a remote server or a vehicle computer of a vehicle on which the EO system 2300 is installed) via a communication module 2310, a display 2312 for displaying an image or other type of result (such as graphics, text results of a spectrometer), another type of output interface (such as a speaker, not shown), and the like.

[0269] The EO system 2300 may include: a controller 2314 that controls a plurality of operating parameters of the EO system 2300 (such as the PDA 2302 and an optional light source 2316). In particular, the controller 2314 may be configured to set (or otherwise change) the plurality of frame exposure times used by the EO system 2300 to capture different frames. Optionally, the plurality of processing results of the plurality of optical detection signals by the processor 2304 may be used to modify the operation of the controller 2314. Optionally, the controller 2314 and the processor 2304 may be implemented as a single processing unit.

[0270] The EO system 2300 may include: at least one light source 2316 operable to emit light onto the field of view (FOV) of the EO system 2300. Some of the light from the light source 2316 is reflected from the objects in the FOV and captured by the PSs 2306 (at least those PSs located in a photosensitive area exposed to external light during the plurality of frame exposure times of the EO system 2300). Detecting light from a plurality of objects in the FOV (whether it is the reflection of the light from the light source, the reflection of other light sources, or radiant light) is used to generate an image or other model (such as a three-dimensional depth map) of the plurality of objects. Any suitable type of light source may be used (such as pulsed, continuous, modulated, LED, laser). Optionally, the operation of the light source 2316 may be controlled by a controller (such as the controller 2314).

[0271] The EO system 2300 may include: a readout circuit 2318 for reading out a plurality of electrical detection signals from a plurality of different PSs 2306. Optionally, the readout circuit 2318 may process the plurality of electrical detection signals before providing them to the processor 2304. Such preprocessing may include, for example: amplification, sampling, weighting, denoising, correcting, digitalization, capping, level-adjustments, dark current compensation, and the like.

[0272] In addition, the EO system 2300 may include: a plurality of additional components, such as (but not limited to) one or more of the following optional components:

[0273] a. A memory module 2308 for storing at least one of the plurality of detection signals output by the plurality of PSs 2306 or by the readout circuit 2318 (if different), and the detection information generated by the processor 2304 by processing the plurality of detection signals.

[0274] b. A power source 2320, such as a battery, an AC power adapter, a DC power adapter, and the like. The power source 2320 can supply power to the PDA, the readout circuit 2318, or any other component of the EO system 2300.

[0275] c. A hard case 2322 (or any other type of structural support).

[0276] d. An optical device 2324 for directing the light of the light source 2316 (if implemented) into the FOV and / or for directing the light from the FOV to the PDA 2300. Such an optical device can include, for example, lenses, mirrors (fixed or movable), prisms, filters, and the like.

[0277] Optionally, the PDA 2302 may be characterized by a relatively high dark current (e.g., as a result of the type and characteristics of its PDs). Due to the high level of dark current, the multiple capacitors of each PS 2306 that collect the detected charge may be saturated (partially or fully) by the dark current, leaving little or no dynamic range for detecting ambient light (from the FOV). Even if the readout circuitry 2318 or the processor 2304 (or any other component of the system 2300) subtracts multiple dark current levels from the detection signal (e.g., normalizes the detection data), there is still a lack of dynamic range for detection, meaning that the resulting detection signals from each PS 2306 are too saturated to meaningfully detect multiple ambient light levels. Since the dark current from the PDs of each PS 2306 is accumulated in the capacitor throughout the entire duration of the frame exposure time (FET) (whether the actual capacitor of other components of the multiple PSs or parasitic capacitance or residual capacitance), multiple different PS 2306 with different capacitances may be rendered unavailable at multiple different FETs.

[0278] Figure 24An example of method 2400 for generating image information based on data of a PDA according to the presently disclosed subject matter is illustrated in the figures. Referring to the numerous examples set forth with respect to the previous figures, method 2400 may be executed by the EO system 2300 (such as by the processor 2304, the controller 2314, etc.). In such a case, the PDA of method 2400 may optionally be the PDA 2302. Other relevant components discussed in method 2400 may be the respective components of the EO system 2300. Method 2400 includes altering a frame FET (FET), in which the PDA collects charges from its PDs. Such collected charges may be due to the photoelectric response to light impinging on the PDs and multiple inherent sources within the detection system, such as due to the dark current of the PDs. The impinging light may arrive from, for example, a field of view (FOV) of a camera or other EO system in which the PDA is mounted. The FET may be controlled electronically, mechanically, or any combination thereof by controlling the flash illumination duration, and the like.

[0279] It should be noted that the FET may be an integral FET, which is a sum of multiple different durations, in which the PDA collects charges due to the photoelectric activity in multiple PSs of the PDA. An integral FET is used in cases where the charges collected over multiple different durations are added together to provide a single output signal. Such an integral FET may be used, for example, with pulsed illumination or with active illumination, in which the collection is suspended for a short period of time (such as to avoid saturation by a bright reflection in the FOV). It should be noted that optionally, in some frames, a single FET may be used, while in other frames, the entire FET may be used.

[0280] Stage 2402 of method 2400 includes receiving first frame information. For each PS of a plurality of PSs of a PDA, the first frame information includes a first frame detection level that indicates an intensity of light detected by the respective PS in a first FET. The receiving of the first frame information may include: receiving multiple readout signals from all the PSs of the PDA, but this is not necessary. For example: certain PSs may be defective and unable to provide a signal. For example: a region of interest (ROI) may be defined for the frame, indicating that data is collected only from a portion of the frame, and so on.

[0281] The frame information can be provided in any format, such as a detection level (or levels) for each PS (e.g., between 0 and 1024, three RGB values, each between 0 and 255, etc.), a scalar, a vector, or any other format. Optionally, the frame information (for the first frame or subsequent frames) can optionally indicate multiple detection signals in an indirect manner (e.g., information about the detection level for a given PS can be given relative to the level of an adjacent PS or relative to the level of the same PS in a previous frame). The frame information can also include: additional information (e.g., sequence number, timestamp, operating conditions), some of which can be used in subsequent steps of method 2400. The first frame information (and the frame information for subsequent frames received at a later stage in method 2400) can be received directly from the PDA or from one or more intermediate units (such as an intermediate processor, memory unit, data aggregator, etc.). The first frame information (and the frame information for subsequent frames received at a later stage in method 2400) can include: the raw data obtained by each PS, but can also include: preprocessed data (e.g., weighted, denoised, corrected, digitized, capped, level adjusted, etc.).

[0282] Stage 2404 includes identifying at least two types of PSs among the plurality of PSs of the PDD based on the first FET:

[0283] a. A group of available PSs for the first frame (referred to as the "first group of usable PSs"), including at least a first PS, a second PS, and a third PS among the plurality of PSs of the PDA.

[0284] b. A group of unavailable PSs for the first frame (referred to as the "first group of unusable PSs"), including at least a fourth PS among the plurality of PSs of the PDA.

[0285] The identification in stage 2404 can be implemented in different ways and can optionally include (either explicitly or implicitly) identifying each of the plurality of PSs as belonging to one of the at least two groups described above. Optionally, each PS of the PDA (or each PS of a predetermined subgroup thereof, such as all PSs of the ROI) can be assigned to one of two complex numbers relative to the first frame, the first available PS group or the first unavailable PS group. However, this is not necessarily required, and some PSs may not be assigned for some frames, or may be assigned to other pluralities (e.g., the availability of multiple PSs is determined based on many parameters other than the FET of the corresponding first frame, such as based on the data being collected). Optionally, the identification in stage 2404 can include: determining which PSs conform to one of the first plurality of PSs and automatically treating the remaining PSs of the PDA (or a predetermined subgroup thereof, such as the ROI) as belonging to the other of the two pluralities.

[0286] It should be noted that the identification in stage 2404 (as well as stages 2412 and 2402) does not have to reflect the actual availability status of the individual PSs (in some implementations, it does indeed reflect these actual availability statuses). For example: A PS included in the first unavailable PS group can actually be used under the plurality of conditions of the first frame, while another PS included in the first available PS group can actually not be used under the plurality of situations of the first frame. The identification in stage 2404 is an estimation or assessment of the availability of the plurality of PSs of the PDA, rather than a test of the individual PSs. It should also be noted that the availability of the plurality of PSs can also be estimated in stage 2404 based on other factors. For example: A pre - existing list of defective PSs can be used to exclude such PSs from being considered available.

[0287] The identification in stage 2404 (as well as stages 2412 and 2420) can include: identifying at least one of the plurality of unavailable PS groups (and / or at least one of the plurality of available PS groups) based on the sum of the durations for which the plurality of sampling PSs of the PDD included in the composite FET are light - sensitive, and excluding the plurality of intermediate times between the durations for which the plurality of sampling PSs of the PDD are light - insensitive.

[0288] The identification of the plurality of available and unavailable PS groups (in the plurality of stages 2404, 2412, and / or 2420) can be based in part on an assessment of temperature. Optionally, method 2400 can include: processing one or more frames (particularly a plurality of previous frames or the current frame) to determine a temperature assessment (such as by assessing the dark current level in a dark frame or in darkened PSs that are not mapped into the FOV). Then, method 2400 can include: using the temperature assessment to identify an available PS group and an unavailable PS group for a later frame, which affects the generation of the corresponding image. The temperature assessment can be used to evaluate how quickly the saturation of the dark current within the duration of the associated FET will saturate the dynamic range of a given PS. Optionally, the temperature assessment can be used to utilize a parameter of an availability model of the PS (such as one generated in method 2500).

[0289] With respect to the execution timing of stage 2402, the execution timing of stage 2404 can vary. For example: stage 2404 can optionally be executed before, simultaneously with, partially simultaneously with, or after the execution of stage 2402. Referring to the example of the accompanying drawings, stage 2404 can optionally be executed by processor 2304 and / or controller 2314. Numerous examples of the many methods for performing the identification of stage 2404 are discussed with respect to method 1100.

[0290] Step 2406 includes: disregarding the plurality of first frame detection levels of the first unavailable PS group and generating a first image based on the plurality of first frame detection levels of the first available PS group. The generation of the first image can be implemented using any suitable method and can optionally be based on additional information (such as data received from an active lighting unit, if used, data from numerous additional sensors such as numerous humidity sensors). Referring to the numerous examples set forth with respect to the previous drawings, it should be noted that stage 2406 can optionally be implemented by processor 2304. It should be noted that the generation can include: processing the plurality of signals at a plurality of different stages (such as weighting, noise reduction, correction, digitization, capping, level adjustment, and the like).

[0291] Regarding the first unavailable PS group, it should be noted that since the detection data of those PSs are ignored in the generation of the first image, multiple replacement values can be calculated in any suitable manner (if required). Such multiple replacement values can be calculated, for example: based on the multiple first-frame detection levels of multiple adjacent PSs, based on the multiple earlier detection levels of multiple earlier frames, based on the same PS (such as if available in a previous frame) or one or more adjacent PSs (such as based on the kinematic analysis of the scene). For example: a one-dimensional Wiener filter, local mean algorithms, non-local means algorithms, and the like can be used. With reference to the generation of multiple images based on the PDA data, optionally, any one or more such images generated (such as the first image, the second image, and the third image) can include: calculating a replacement value for at least one pixel, the at least one pixel being associated with a PS that is identified as unavailable for the corresponding image based on the detection levels of at least one other adjacent PS identified as available for the corresponding image. In the case of using a non-binary availability assessment (and the identification in stages 2404, 2412, and / or 2420 includes identifying at least one PS as belonging to a third group of partially available PSs), the detection signal of each such PS is partially identified as available, and it can be combined or averaged with the detection signals of multiple adjacent PSs and / or multiple other readings of the same PS at other times when it is available (or partially available).

[0292] Optionally, the generation of the first image (and later the second and third images) can also include: disregarding the outputs of multiple PSs determined to be defective, inoperative, or unavailable for any other reason, or detection paths determined to have a defect, be inoperative, or be unavailable. An example of an additional method for detecting defects in multiple PSs and / or multiple related detection paths is discussed with respect to method 2200, which can be combined with method 2400. The output of method 2200 can be used to generate stages 2406, 2414, and 2422. In such a case, method 2200 can be executed periodically and provide outputs for generating the multiple images, or can be specifically triggered according to method 2400 for the generation of the multiple images.

[0293] Optionally, the generation of the first image (and the second and third images, later) may include: when a PS is determined to be available, calculating a replacement value for at least one pixel associated with the PS based on a detected level of the measured PS, where the PS is identified as not available for the corresponding image. Such information may be used together with information of multiple adjacent PSs or independently of them. Using multiple detected levels of a PS from other times may include, for example: considering multiple detected levels from multiple previous frames (such as for multiple static scenes), using detection information from another snapshot of a series of image acquisitions used to generate a composite image, such as a high-dynamic range image (HDRI) or a multi-wavelength composite image (where several shots are taken using different spectral filters and then combined into a single image).

[0294] It should be noted that in the first image (and in any other frame generated based on the detection data of the PDA), a single pixel may be based on the detection data from a single PS or from a combination of multiple PSs; similarly, the information from a single PS can be used to determine the pixel color of one or more pixels on the image. For example, a field of view of Θ multiplied by Φ degrees can be covered by multiple X by Y PSs and can be converted into N by N pixels in the image. The pixel value of one of these M×N pixels can be calculated as the sum of Pixel-Value(i,j) = Σ(ap , s·DLp , s), where DLp , s is the detected level of the PS(p,s) for the frame, and ap,s is an average coefficient for the specific pixel (i,j).

[0295] After stage 2406, the first image can then be provided to an external system (such as a screen monitor, a storage unit, a communication system, an image processing computer). The first image can then be processed using one or more image processing algorithms. After stage 2406, the first image can then be processed in other ways as desired.

[0296] For many frames captured by the photodetector sensor, whether consecutive or not, stages 2402 to 2406 can be reiterated several times. It should be noted that in some implementations, such as if high dynamic range (HDR) imaging techniques are implemented, the first image can be generated based on multiple detection levels of several frames. In other implementations, the first image is generated by multiple first-frame detection levels of a single frame. Multiple instances of stages 2402 and 2406 can follow a single instance of stage 2404 (such as if the same FET is used for several frames).

[0297] Stage 2408 is performed after receiving the first frame information and includes: determining a second FET that is longer than the first FET. The determination of the second FET includes determining a duration of the exposure of the multiple associated PDs (such as in milliseconds, its fractions, or its multiples). Stage 2408 may also include: determining multiple additional timing parameters (such as the start time of the exposure), but this is not necessary. The second FET that is longer than the first FET can be selected for any reason. Such a reason may include, for example, any one or more of the following: the overall light intensity in the FOV, the light intensity in multiple parts of the FOV, using bracketing techniques, using high dynamic range photography techniques, aperture changes, and the like. The second FET can be longer than the first FET by any ratio, whether a relatively low value (such as ×1.1 times, ×1.5 times), a value exceeding several times (such as ×2, ×5), or a higher value (such as ×20, ×100, ×5,000). Referring to the examples in the accompanying drawings, stage 2408 can optionally be performed by controller 2314 and / or processor 2304. Optionally, an external system can determine the first FET or affect the settings of the FET through EO system 2300 (such as a control system of a vehicle equipped with EO system 2300).

[0298] It should be noted that, optionally, at least one of stage 2408 and stage 2416 can be replaced by making a decision with such an external entity for a new FET (the second FET and / or the third FET respectively). Such an external entity can be, for example, an external controller, an external processor, an external system. It should be noted that, optionally, at least one of stage 2408 and stage 2416 can be replaced by receiving an indication of a new FET (the second FET and / or the third FET respectively) from an external entity. The indication of the FET can be explicit (such as a duration in milliseconds) or implicit (such as an indication of a change in the aperture opening and / or exposure value (EV) corresponding to the FET, an indication of the flash duration). It should be noted that, optionally, at least one of stage 2408 and stage 2416 can be replaced by receiving from an external entity an expected dark current (or at least a part of the dark current is transmitted to the capacitor of the PS, such as if many dark current mitigation strategies are implemented).

[0299] Stage 2410 includes receiving second frame information. The second frame information includes a second frame detection level for each of the plurality of PSs of the PDA, and the second frame detection level indicates an intensity of light detected by the corresponding PS in the second FET. It should be noted that the second frame (in which the detection data for the second frame information is collected) can directly follow the first frame, but this is not necessary. The plurality of FETs in any one of one or more intermediate frames (if any) between the first frame and the second frame can be equal to the first FET, the second FET, or any other FET (longer or shorter). Referring to the example in the accompanying drawings, stage 2410 can optionally be executed by the processor 2304 (such as via the readout circuit 2318).

[0300] Stage 2412 includes identifying at least two types of PSs of the PDA from the plurality of PSs of the PDD based on the second FET:

[0301] a. A group of available PSs for the second frame (referred to as the "second group of usable PSs") includes the first PS.

[0302] b. A group of unavailable PSs for the second frame (referred to as the "a second group of unusable PSs") includes the second PS, the third PS, and the fourth PS.

[0303] That is, since the FETs of the second frame are longer, the second PS and the third PS that are identified as belonging to the first available PS group in stage 2404 (i.e., the available PS group for the first frame mentioned above) are identified as belonging to the second unavailable PS group in stage 2412 (i.e., the unavailable PS group for the second frame mentioned above). The identification in stage 2412 can be implemented in different ways, such as any one or more of those discussed above with respect to stage 2404. For various reasons, multiple PSs that are considered available for shorter FETs may be considered unavailable for longer FETs in stage 2412. For example: If such a PS has a charge storage capacity (such as capacitance) lower than the average charge storage capacity of multiple PSs in the PDA, then the charge storage capacity of these PSs may be considered insufficient for both the detection signal and the cumulative dark current over a longer integration time. If the dark current level is maintained (such as the temperature and bias voltage on the PD remain unchanged), then any PS that cannot be presented in the first FET due to its inability to maintain sufficient dynamic range will also be identified as unavailable for the longer second FET.

[0304] Stage 2412 is executed after stage 2408 (because it is based on the multiple outputs of stage 2408). The execution timing of stage 2412 can be changed relative to the execution timing of stage 2410. For example: Stage 2412 can optionally be executed before, simultaneously, partially simultaneously, or after executing stage 2410. Referring to the example of the accompanying drawings, stage 2412 can optionally be executed by processor 2304. Many examples of the many methods for performing the identification in stage 2412 are discussed with respect to method 2500.

[0305] Stage 2414 includes: disregarding a plurality of second frame detection levels of the second unavailable PS group, and generating a second image based on the plurality of second frame detection levels of the second available PS group. Importantly, stage 2414 includes generating the second image while ignoring the plurality of outputs (the plurality of detection levels) of at least two PSs, and the plurality of outputs of the at least two PSs are used to generate the first image. Based on the FET of the first frame, these at least two PSs are identified as available and are identified as being available for generating the first image (i.e., at least the second PS and the third PS). The generation of the second image can be implemented using any suitable method, including any method, technique, and variation discussed above regarding the generation of the first image. Regarding the second unavailable PS group, it should be noted that since the detection data of those PSs are ignored in the generation of the second image, a plurality of replacement values can be calculated in any suitable manner (if needed). After stage 2414, the second image can then be provided to an external system (such as a screen monitor, a storage unit, a communication system, an image processing computer), and then can be processed using one or more image processing algorithms, or other processing can then be performed as needed.

[0306] For many frames captured by the photodetector sensor, whether consecutive or not, stages 2410 to 2414 can be repeatedly executed multiple times. It should be noted that in some implementations, for example, if high dynamic range (HDR) imaging technology is implemented, the second image can be generated based on the plurality of detection levels of several frames. In other implementations, the second image is generated through the plurality of second frame detection levels of a single frame. Multiple instances of stages 2410 and 2414 can follow a single instance of stage 2412 (such as if the same second FET is used for several frames).

[0307] Step 2416 is performed after receiving the second frame information and includes: determining a third FET that is longer than the first FET and shorter than the second FET. The determination of the third FET includes: determining a duration (e.g., in milliseconds, fractions thereof, or multiples thereof) of the exposure for the plurality of associated PDs. Stage 2416 may also include: determining a plurality of additional timing parameters (e.g., a start time of the exposure), but this is not required. The third FET may be selected for any reason, such as the reasons discussed above for the determination of the second FET in stage 2408. The third FET may be longer than the first FET by any ratio, whether a relatively low value (e.g., ×1.1 times, ×1.5 times), a value more than a few times (e.g., ×2, ×5), or any higher value (e.g., ×20, ×100, ×5,000). The third FET may be shorter than the second FET by any ratio, whether a relatively low value (e.g., ×1.1 times, ×1.5 times), more than a few times (e.g., ×2, ×5), or any higher value (e.g., ×20, ×100, ×5,000). Referring to the example of the accompanying drawings, stage 2416 may optionally be performed by controller 2314 and / or processor 2304. Optionally, an external system may determine the first FET or affect the setting of the FET via EO system 2300.

[0308] Stage 2420 of method 2400 includes receiving a third frame information. The third frame information includes a third frame detection level for each of the plurality of PSs of the PDA, the third frame detection level indicating an intensity of light detected by the corresponding PS in the third FET. It should be noted that the third frame (in which the detection data for the third frame information is collected) may directly follow the second frame, but this is not required. The plurality of FETs in any one of one or more intermediate frames (if any) between the second frame and the third frame may be equal to the second FET, the third FET, or any other FET (longer or shorter). Referring to the example of the accompanying drawings, stage 2420 may optionally be performed by processor 2304 (e.g., via readout circuit 2318).

[0309] Step 2420 includes identifying at least two types of PSs of the PDA from the plurality of PSs of the PDD based on the third FET:

[0310] a. A group of available PSs for the third frame (referred to as "third group of usable PSs") includes the first PS and the second PS.

[0311] b. A group of unusable PSs for the third frame (referred to as "a third group of unusable PSs") includes the third PS and the fourth PS.

[0312] That is, since the FET of the third frame is longer than that of the first frame, the second PS is identified as belonging to the first group of available PSs (i.e., the aforementioned group of available PSs for the first frame) in stage 2404 and is identified as belonging to the third group of unusable PSs (i.e., the aforementioned group of unusable PSs for the third frame) in stage 2420. Since the FET of the third frame is longer than that of the second frame, the third PS is identified as belonging to the second group of unusable PSs (i.e., the aforementioned group of unusable PSs for the second frame) in stage 2412 and is identified as belonging to the third group of available PSs (i.e., the aforementioned group of available PSs for the third frame) in stage 2420.

[0313] The identification in stage 2420 can be implemented in different ways, such as any one or more of those discussed above regarding stage 2404. For various reasons, such as those discussed above regarding stage 2412, a plurality of PSs that are considered available for a shorter FET may be considered unusable for a longer FET in stage 2420. For various reasons, a plurality of PSs that are considered unusable for a longer FET may be considered available for the shorter FET in stage 2420. For example, if such a plurality of PSs have a charge storage capacity (such as capacitance) greater than that of some PSs in the second group of unusable PSs, the charge storage capacity of those different PSs can be considered sufficient for the detection signal and the accumulated dark current within a shorter integration time than that of the second FET.

[0314] Stage 2420 is executed after stage 2416 (because it is based on the outputs of stage 2416). The execution timing of stage 2420 can be changed relative to the execution timing of stage 2416. For example, stage 2420 can optionally be executed before, simultaneously with, partially simultaneously with, or after the execution of stage 2416. Referring to the example of the accompanying drawings, stage 2420 can optionally be executed by processor 2304 and / or controller 2314. Many examples of the methods for performing the identification in stage 2420 are discussed regarding method 1100.

[0315] Stage 2422 includes: disregarding the multiple third frame detection levels of the third unavailable PS group, and generating a third image based on the multiple third frame detection levels of the third available PS group. Importantly, stage 2422 includes generating the third image while ignoring the multiple outputs (detection levels) of at least one PS, the multiple outputs of the at least one PS being used for the generation of the first image (such as the second PS), and while utilizing the multiple outputs of at least one PS, the multiple outputs of the at least one PS being used for the generation of the second image (such as the third PS). The generation of the third image can be implemented using any suitable method, including any method, technique, and variant discussed above regarding the generation of the first image. Regarding the third unavailable PS group, it should be noted that since the detection data of these PSs are ignored in the generation of the third image, multiple replacement values can be calculated in any suitable manner (if needed). After stage 2422, the third image can be provided to an external system (such as a screen monitor, a storage unit, a communication system, an image processing computer). After stage 2422, the third image can be processed using one or more image processing algorithms. After stage 2422, the third image can then be processed in other ways as desired.

[0316] Optionally, the generation of one or more images (such as the first image, the second image, the third image) in method 2400 can be based on a previous stage that evaluates the dark current accumulation of at least one PS for the corresponding image, such as based at least on the corresponding FET, electrical measurements in the captured optical signal or near the optical signal, and the like. For example: such measurements can include: measuring the dark current (or another indicative measurement) on a reference PS that is kept in the dark. The generation of the corresponding image can include: subtracting an amplitude related to the dark current evaluation of the PS from the detection signals of one or more PSs to give a more accurate characterization of the FOV of the PDA. Optionally, the compensation for dark current accumulation in this stage is only performed for the multiple available PSs of the corresponding image.

[0317] In a PDA characterized by a relatively high dark current (e.g., as a result of the type and characteristics of its multiple PDs), the capacitance of each PS where the detected charge is collected may become saturated (partially or fully) due to the dark current, leaving little dynamic range for detecting ambient light (arriving from the field of view of the system). Even when a means for subtracting multiple dark current levels from the multiple detection signals is implemented (e.g., to normalize the detection data), the lack of dynamic range for detection means that the resulting signal is either completely saturated or not sufficient to meaningfully detect multiple ambient light levels. Since the dark current from the PD accumulates in the FET in the capacitance (whether parasitic capacitance or residual capacitance of the actual capacitors or other components of the multiple PSs), the method uses the FET to determine the PS available for the corresponding FET, and after collecting the charge of the dark current (or at least its relevant part) for the entire FET, there will be sufficient dynamic range left in the capacitance. The identification of a group of unavailable PSs for a frame may include: given the FET for the corresponding frame, identifying multiple PSs whose dynamic range is below an acceptable threshold (or otherwise expected to fail a dynamic range sufficiency criterion). Similarly, the identification of a group of available PSs for a frame may include: given the FET for the corresponding frame, identifying multiple PSs whose dynamic range is above an acceptable threshold (or otherwise expected to meet a dynamic range adequacy criterion). The aforementioned two acceptable thresholds may be the same threshold or different thresholds (e.g., if the dynamic ranges of multiple PSs are treated differently between those thresholds, such as being identified as part of the available PS group for the relevant frame).

[0318] Generally referring to method 2400, it should be noted that for multiple additional FETs (e.g., a fourth FET, and the like), multiple additional instances of stages 2416, 2418, 2420, and 2422 may be repeated. Such time may be longer, shorter, or equal to any previously used FET. It should also be noted that, optionally, the first FET, the second FET, and the third FET are multiple consecutive FETs (i.e., no other FETs are used by the PDA between the first FET and the third FET). Alternatively, other FETs may be used between the first FET and the third FET.

[0319] It should be noted that even if the exposure value (EV) remains the same, multiple different available PS groups and unavailable PSs can be determined for different FETs in method 2400. For example: Consider a situation where the first FET is scaled by a factor q to provide the second FET, but the f number is increased by a factor q such that the total illuminance received by the PDA is substantially the same. In such a case, even if the EV remains constant, the second unavailable PS group will include additional PSs other than those included in the first unavailable PS group because the dark current accumulation grows by a factor p.

[0320] A non-transitory computer-readable medium is provided for generating image information based on data of a PDA. The non-transitory computer-readable medium includes a plurality of instructions stored thereon, which, when executed on a processor, perform the following steps: receiving first frame information, the first frame information including a first frame detection level for each of a plurality of photosensors (PSs) of the PDA, the first frame detection level indicating a light intensity detected by each PS in a first field-effect transistor (FET); based on the first FET, identifying from the plurality of PSs of the PDA: a first available PS group including a first PS, a second PS, and a third PS, and a first unavailable PS group including a fourth PS; disregarding the first frame detection levels of the first unavailable PS group and generating a first image based on the first frame detection levels of the first available PS group; after receiving the first frame information, determining a second FET that is longer than the first FET; receiving second frame information, the second frame information including a second frame detection level for each of the plurality of PSs of the PDA, the second frame detection level indicating a light intensity detected by each PS in a second FET; based on the second FET, identifying from the plurality of PSs of the PDD: a second available PS group including the first PS, and a second unavailable PS group including the second PS, the third PS, and the fourth PS; disregarding the second frame detection levels of the second unavailable PS group and generating a second image based on the second frame detection levels of the second available PS group; after receiving the second frame information, determining a third FET that is longer than the first FET and shorter than the second FET; receiving third frame information, the third frame information including a third frame detection level for each of the plurality of PSs of the PDA, the third frame detection level indicating a light intensity detected by each PS in a third FET; based on the third FET, identifying from the plurality of PSs of the PDD: a third available PS group including the first PS and the second PS, and a third unavailable PS group including the third PS and the fourth PS; and disregarding the third frame detection levels of the third unavailable PS group and generating a third image based on the third frame detection levels of the third available PS group.

[0321] The non-transitory computer-readable medium of the previous paragraph may include: a plurality of additional instructions stored thereon, which, when executed on a processor, perform any other steps or variations discussed above with respect to method 2400.

[0322] Figure 25FIG. 2500 is a flow chart of a method for generating a model for PDA operation in different FETs, showing various examples according to the presently disclosed subject matter. Identifying which of the plurality of PSs belong to an available PS group provided with a given FET (and possibly additional parameters such as temperature, bias across multiple PDs, capacitance of multiple PSs, etc.) can be based on a model of the behavior of each of the plurality of PSs in different FETs. Such modeling can be part of method 2400 or can be performed separately prior to it. For each of the plurality of PSs of a plurality of PDAs (such as PDA 1602), and possibly for all PSs of the photodetector array, multiple stages 2502, 2504, and 2506 of method 2500 are performed.

[0323] Step 2502 includes determining the availability of the corresponding PS for each of the plurality of different FETs. The determination of the availability can be performed in different ways. For example: A detection signal of the PS can be compared with an expected value (such as completely dark or a known higher illumination level if the illumination level is known), compared with an average value among other PSs, compared with multiple detection levels among other PSs (such as if all PSs are imaging a color-uniform target), compared with multiple detection results among other FETs (such as determining whether the detection level at a duration T, e.g., 200 nanoseconds, is approximately twice the detection level at T / 2, e.g., 330 nanoseconds), and so on. The determined availability can be a binary value (such as available or unavailable), a non-binary value (such as a scalar evaluating the availability level or indicating its availability), a set of values (such as a vector), or any other suitable format. Optionally, the same plurality of frame FETs are used for all PSs of the plurality of PSs, but this is not necessary. For example: In a non-binary availability assessment, an intermediate value between completely unavailable and completely available may indicate that at other available times (or partially available times), the detection signal of the corresponding PS should be combined or averaged with the detection signals of multiple adjacent PSs and / or with other readings of the same plurality of PSs.

[0324] Method 2500 may include an optional stage 2504 of measuring the charge accumulation capacity and / or saturation parameters of the corresponding PS. The charge capacity can be measured in any suitable way, such as using the PD, other power sources in the PS (such as a current source), other power sources in the PDA, or an external power source (such as a calibration machine in a manufacturing factory for manufacturing photodetectors). Stage 2504 can be omitted, for example: in cases where the difference in capacitance between different PSs is negligible or simply ignored.

[0325] Stage 2506 includes creating a usability prediction model for a corresponding PS, where the usability prediction model provides an estimate of the usability of the PS during different FET operations, and these different FETs are not included in the multiple FETs for which the usability is actively determined in stage 2502. The multiple different FETs can be included in the same duration span of the multiple FETs in stage 2502, either longer or shorter than it. The created usability prediction model can provide different types of usability indications, such as: a binary value (e.g., available or unavailable), a non-binary value (e.g., a scalar evaluation of usability or an indication thereof), a set of values (e.g., a vector), or any other suitable format. The type of usability indicated by the model can be the same type of usability as determined in stage 2502 or a difference thereof. For example: stage 2502 can include: evaluating the dark current collected in different FETs, while stage 2504 can include: determining a time threshold, where the time threshold indicates the maximum allowable FET for which this PS is considered usable. Optionally, the usability model can consider the charge accumulation capacity of each PS.

[0326] Any suitable method can be used to create the usability prediction model. For example: for different FETs, different dark currents can be measured or evaluated for the PD, and then a regression analysis can be performed to determine a function (polynomial, exponential, etc.) that can evaluate the dark current in other multiple FETs.

[0327] Optional stage 2508 includes: for at least a portion of the PDAs, at least including the multiple PSs of the previous stage, compiling a usability model. For example: stage 2508 can include: generating one or more matrices or other types of mappings, where the mappings store multiple model parameters for each PS in its multiple cells. For example: if stage 2506 includes creating a dark current linear regression function for each PS (p, s), and the dark current linear regression function is given by DarkCurrent(p, s) = Ap , s·τ + Bp , s (where τ is the FET, and Ap , s and Bp , s are the linear coefficients of the linear regression), then a matrix A can be generated to store multiple different Ap , s values, and a matrix B can be generated to store multiple different Bp , s values. If needed, a third matrix C can be used to store different capacitance values Cp for multiple different PSs ,s (or different saturation values Sp , s).

[0328] Stage 2506 (or stage 2508, if implemented) may be followed by an optional stage 2510 that includes determining the availability of a plurality of PSs for one of the plurality of FETs for stage 2502 based on the plurality of results of stage 2506 (or stage 2508, if implemented). For example: stage 2510 may include creating a mask (such as a matrix) of unavailable PSs for a plurality of different PSs of the photodetector array.

[0329] Referring fully to method 2500, stage 2502 may include determining the dark current of each PS of the PDA at four different FETs (such as 33 ns, 330 ns, 600 ns, and 2000 ns). Stage 2504 may include determining a saturation value for each PS, and stage 2506 may include creating a polynomial regression for the dark current accumulation over time for each PS. Stage 2508 in this example may include generating a matrix that stores the FETs in each cell, where the dark current of the PS (according to regression analysis) will saturate the PS. Stage 2510 may include receiving a new FET and determining whether each cell of the matrix is below or above the stored value by generating a binary matrix that stores a first value (such as "0") for each unavailable PS (where the FET is higher than the stored value) and a second value (such as "1") for each available PS (where the FET is lower than the stored value).

[0330] Any stage of method 2500 may be performed during the manufacturing process of the PDA (such as during factory calibration), during the operation of the system (such as after installing an EO system including the PDA in its designated location, such as a vehicle, surveillance system, etc.), or at any other suitable time between or after these times. Different stages may be performed at different times.

[0331] Referring fully to method 2400, it should be noted that it can be extended to measure the effect of dark current on a plurality of different PSs in a plurality of different FETs under different operating conditions (such as when different ones are subjected to different temperatures, when different biases are supplied to a plurality of PDs) at different stages.

[0332] Optionally, the determination of a FET (such as the second FET, the third FET) as part of method 2400 may include: maximizing the corresponding FET while keeping a number of unavailable PSs for the corresponding frame below a predetermined threshold. For example, to maximize the collection of multiple signals, method 2400 may include: setting a FET close to a threshold related to a predetermined number of unavailable PSs (such as requiring at least 99% of the multiple PSs of the PDA to be available, allowing up to 1% of the multiple PSs to be unavailable). It should be noted that in some cases, the maximization may not yield the exact maximum duration, but a duration close to it (such as more than 320% or more than 325% of the mathematical maximum duration). For example, the maximum frame duration among multiple discrete predefined time spans may be selected.

[0333] For example, the determination of a FET as part of method 2400 may include: determining a FET that is longer than other possible FETs, resulting in more multiple PSs than a previous FET, such that a higher number of multiple PSs are considered unavailable compared to such other possible FETs, but improving the image quality in the remaining multiple PSs. This may be useful, for example, in relatively dark conditions. It should be noted that optionally, the determination of the FET (such as by attempting to maximize it) may consider the spatial distribution of the multiple PSs that are considered unavailable among multiple different FETs. For example, knowing that in certain regions of the PDA, a cumulative multiple PSs have a high percentage of the PSs that will be considered unavailable above a certain FET may result in determining a FET below the threshold, especially if this is an important part of the FOV (such as at the center of the FOV, or at the location where a pedestrian or vehicle was identified in a previous frame).

[0334] Method 2400 may include: creating a single image based on multiple detection levels of two or more frames in which multiple different FETs are detected, where multiple different unavailable PS groups are used for different FETs. For example, three FETs may be used: ×1, ×10, and ×100. The color determined for each pixel of the image may be determined based on the multiple detection levels of one or more PSs (such as the FETs in which the PS is available, not saturated, and detecting a non-negligible signal) or the multiple detection levels of multiple adjacent PSs (such as if no available detection signal is provided, even if the corresponding PS is determined to be available, such as because the signal is negligible in such a case). Method 2400 may include: determining multiple FETs for combining different exposures of a single image (such as using high dynamic range imaging techniques, HDR). The determination of such FETs may be based on modeling the different PS availabilities among the multiple different FETs, such as the model generated in method 2500. Method 2400 may also include: determining to capture a single image in two or more different detection instances (where the multiple detection signals are read separately in each instance and then added together), with each detection instance providing a sufficient number of available PSs. For example, instead of using a 2 ms FET for a single capture of a scene, method 2400 may include: determining to capture the scene twice (such as two 1 ms FETs, a 1.5 ms and a 0.5 ms FET), such that the number of available PSs in each exposure will exceed a predetermined threshold.

[0335] Optionally, method 2400 may include: determining at least one FET based on a model of the availability of different PSs in different FETs (such as the one generated in method 2500) and saturation data of at least one previous frame captured by the PDA. The saturation data includes information about multiple PSs that saturated in at least one FET of at least one previous frame (such as the number of multiple PSs, which PSs, which parts of the PDA) and / or information about multiple PSs that were almost saturated in at least one FET of at least the previous frame. The saturation data may be related to the immediately preceding frame (or several frames), and thus it indicates the saturation behavior of a curtain imaged scene.

[0336] Method 2400 may further include: modeling the availability of multiple PSs of the PDA across multiple different FETs (e.g., by implementing Method 2500 or any other suitable modeling method). Providing an availability model of the multiple PSs of the PDA across multiple different FETs (either as part of Method 2400 or not part of Method 2400), Method 2400 may include: (a) determining at least one of the second FET and the third FET based on the results of the modeling; and / or (b) identifying at least one of the multiple groups of unavailable PSs based on the results of the modeling.

[0337] Optionally, in determining any one or more FETs, Method 2400 may include: determining a FET that balances between extending the FET and reducing the FET due to the darkness of the FOV scenario to limit the number of PSs rendered unavailable, the number of which increases with longer FETs (e.g., based on the model of Method 2500). For example: when at the same temperature and with a bias on the PD (such that the dark current in each FET remains constant), stage 2408 may include: determining a longer FET as the scenario becomes darker (at the cost of a large number of unavailable PSs), and stage 2416 may include: determining a shorter FET as the scenario brightens again (thereby reducing the number of unavailable PSs). This is particularly important in darker images, where the availability of multiple PSs caused by dark current accumulation (which is caused by temperature and operating conditions rather than illumination level) limits the extension of the FET, which would occur if dark current accumulation did not significantly limit the dynamic range of each PS. In another example, within a time span in which the scene illumination remains constant, stage 2408 may include: determining a longer FET enabled due to a temperature drop (thereby reducing the dark current and the percentage of unavailable PSs on each FET), while stage 2416 may include: determining a shorter FET as the temperature of the PDA rises again.

[0338] Figure 26 is a graphical representation of the execution of Method 2400 for three frames taken of the same scenario across different FETs according to many examples of the subject matter of the present disclosure. The example scenario includes four concentric rectangles, each rectangle being darker than the surrounding rectangle. Figure 26 The different figures correspond to a stage of Method 2400 and are numbered with an equivalent reference numeral with a prime. For example: Figure 2406’ matches an execution of stage 2406, and so on. Each rectangle in the lower nine figures represents a single PS, or a pixel that directly maps to such a PS (in the lower three figures). In all figures, the positions of the multiple PSs relative to the PDD remain constant.

[0339] As is common in many types of PDAs, the PDA that receives frame information from it may include many defective, malfunctioning, or otherwise misbehaving PSs (also referred to as defective, malfunctioning, or otherwise misbehaving pixels). The term "misbehaving PS" broadly relates to a PS that deviates from its expected response, including but not limited to: stuck, dead, hot, lit, warm, defective, and flashing PSs. The misbehaving PSs may be a single PS or a cluster of multiple PSs. Many non-limiting examples of the many defects that may cause a PS to misbehave include: PS bump bond connectivity, addressing faults in the multiplexer, vignetting, severe sensitivity deficiency of some PSs, non-linearity, poor signal linearity, low full well, poor mean-variance linearity, excessive noise, and high dark current. One or more PSs identified as an unavailable PS in method 2400 may be a permanently defective PS or a PS that misbehaves based on conditions unrelated to the FET (such as due to high temperature). Such PSs may be identified as unavailable for all FETs in method 2400 (such as PS 8012.5). However, it should be noted that due to limited functionality and a long enough FET (such as PS 8012.4), some functional PSs (not "misbehaving") may be considered unavailable for all FETs in method 2400. Optionally, method 2400 may include determining the availability of one or more PSs of the PDA based on other parameters besides the FET (such as temperature, various electrical parameters, ambient light level). It should be noted that in such a case, due to other considerations (such as temperature), a PS that is rendered unavailable due to the FET generally cannot be considered available due to its capacitance limitations.

[0340] In the example shown:

[0341] a. Under all conditions, PS 8012.5 may not have an output signal, regardless of the amount of light impinging on it in all three FETs (T1, T2, T3).

[0342] b. Under all conditions, PS 8012.4 may output a saturated signal, regardless of the amount of light impinging on it in all three FETs (T1, T2, T3).

[0343] c. PS 8012.3 outputs an available signal in the shortest FET (T1), but an unavailable (saturated) signal in the longer FETs (T2 and T3).

[0344] d. PS 8012.2 outputs an available signal in multiple shorter FETs (T1 and T3), but an unavailable (saturated) signal in the longest FET (T2).

[0345] It should be noted that other types of defects and incorrect outputs may also occur. For example, such errors may include: outputting a highly non-linear signal response, consistently outputting too strong a signal, consistently outputting too weak a signal, outputting random or semi-random output, and so on. Similarly, many PSs (such as the first PS 8012.1) can be used to detect all FETs used in the detection.

[0346] Back to Figure 23 , it should be noted that, optionally, system 2300 can be an EO system with dynamic PS availability assessment capabilities. That is, EO system 2300 can be capable of alternately allocating many different PSs as available or unavailable based on the FETs and possibly other operating parameters, and utilizing the detection signals of multiple PSs only when each PS is determined to be available at the time of capture (such as according to an availability model).

[0347] In such a case, EO system 2300 includes:

[0348] a. A PDA 2302, which includes a plurality of PSs 2306, each of which is operable to output a plurality of detection signals in different frames. The detection signals output by the corresponding PS 2306 for a frame indicate the amount of light impinging on the corresponding PS in a corresponding frame (and may also indicate the dark current of the PD of the corresponding PS).

[0349] b. An availability filtering module (such as implemented as part of the processor 2304, or implemented separately). The availability filtering module is operable to determine for each PS

[0350] 2306 that the PS is unavailable (which may be different between different PSs 2306), and later determine that the same PS 2306 is available based on a second FET that is shorter than the first FET. That is, a plurality of PSs 2306 that are unavailable at a certain point (and whose outputs are ignored when generating one or more images) may later become available again (such as if the FET becomes shorter), and the outputs of these PSs 2306 may be useful for generating a plurality of subsequent images again.

[0351] c. The processor 2304 is operable to generate a plurality of images based on the multiple frame detection levels of the plurality of PSs 2306. In other configurations of the processor 2304, it is configured to: (a) exclude a first detection signal of a filtered PS when generating a first image based on multiple first frame detection levels, the first detection signal of the filtered PS being determined by the availability filtering module to be unavailable for the first image, and (b) include a second detection signal of the filtered PS determined by the availability filtering module to be available for the second image when generating a second image based on multiple second frame detection levels captured by the PDA after capturing the multiple first frame detection levels.

[0352] Optionally, the controller 2314 may determine different FETs for different frames based on the different illumination levels of a plurality of objects in the field of view of the EO system.

[0353] Optionally, the controller 2314 may be configured to determine a plurality of FETs for the EO system by maximizing the plurality of FETs while keeping the number of unavailable PSs for each frame below a predetermined threshold (such as as discussed with respect to method 2400).

[0354] Optionally, the EO system 2300 may include: at least one shielded PD that is shielded (e.g., by a physical barrier or using deflecting optics) from ambient illumination; and dedicated circuitry operable to output an electrical parameter indicative of the level of dark current based on the signal level of the at least one shielded PD. The processor 2304 may be configured to generate a plurality of images based on the electrical parameter, based on the respective FETs, and based on the plurality of detection signals of the PDA, thereby compensating for different degrees of dark current accumulation in different frames.

[0355] Optionally, the processor 2304 may be used to calculate a replacement value for at least one pixel of the first image associated with the filtered PS based on a detected level of the filtered PS measured when the PS is identified as available. Optionally, the processor 2304 may be configured to calculate a plurality of replacement values for a plurality of PSs based on the detected levels of a plurality of adjacent PSs when the detection signals of the respective PSs are excluded from the generation of the plurality of images. Optionally, the processor 2304 may be operated based on a first frame detected level of a plurality of adjacent PSs to calculate a replacement value for at least one pixel of the first image associated with the filtered PS.

[0356] Optionally, the processor 2304 (or an availability filter module, if not part of the processor) may be operated to determine a degree of availability for a plurality of PSs based on an FET, the degree including a sum of durations during which the plurality of PSs of the PDD are sampled as being light sensitive and excluding a plurality of intermediate times between the plurality of durations during which the plurality of PSs are sampled as being light insensitive.

[0357] Optionally, the processor 2304 may utilize an availability model generated according to method 2500 to determine when to include and when to exclude the detection signals of different PSs captured by different FETs. Optionally, the EO system 2300 may be operated to perform method 2500. Optionally, the EO system 2300 may be configured to participate in the execution of method 2500 with an external system (such as a factory calibration machine used in the manufacture of the EO system 2300).

[0358] Figure 27FIG. 0 is a flow chart showing an example of a method 3500 according to the presently disclosed subject matter. The method 3500 is used to generate a plurality of images based on different subsets of a plurality of PSs under different operating conditions. Referring to the many examples set forth with respect to the previous figures, the method 3500 may be executed by a processor 1604, where the PDA of the method 3500 may optionally be the PDA 1602. The method 3500 includes at least a plurality of stages 3510, 3520, 3530, and 3540, which are repeated in sequence for different frames captured by a photodetector array. The sequence may be performed in its entirety for each frame in a stream, but need not be, as discussed in more detail below.

[0359] The sequence begins at stage 3510, which receives frame information from the PDA that indicates a plurality of detection signals provided for the frame by a plurality of PSs of the PDA. The frame information may include: the detection level (or levels) of each PS (such as between 0 and 1024, three RGB values, each between 0 and 255, and the like), or any other format. The frame information may indicate the plurality of detection signals in an indirect manner (such as the level relative to that of an adjacent PS or relative to the same PS in a previous frame to give information related to the detection level of a given PS). The frame information may also include: additional information (such as a sequence number, a timestamp, an operating condition), some of which may be used in subsequent steps of the method 3500. The frame information received from the PDA may include PSs that are defective, faulty, or otherwise behave abnormally.

[0360] Stage 3520 includes receiving operating condition data during the frame duration that indicates a plurality of operating conditions of the PDA. The plurality of operating conditions may be received from different types of entities, such as any one or more of the following entities: the PDA, a controller of the PDA, the at least one processor executing the method 3500, one or more sensors, one or more controllers of the at least one processor executing the method 3500, and the like. A plurality of non-limiting examples of the plurality of operating conditions that may be mentioned in stage 3520 include the FETs of the PDA (such as an electronic or mechanical shutter, a flash illumination duration, and the like), the amplification gain of the PDA or the connected circuitry, the bias voltage supplied to the plurality of PDs of the PDA, the ambient light level, a dedicated illumination level, the image processing mode of a downstream image processor, the filtering applied to the light (such as spectral filtering, polarization), and the like.

[0361] Stage 3530 includes determining a defective PS group based on the operating condition data, which includes at least one of the plurality of PSs and excludes a plurality of other PSs. When stage 3530 is performed for different frames based on different operating condition data for which these frames are received in different corresponding instances of stage 3520, different defective PS groups are selected for different frames whose operating conditions are different from each other. However, the same set of defective pixels may be selected for two frames having different operating conditions (such as when the difference in operating conditions is relatively small).

[0362] It should be noted that the determination is based on the operating condition data and not on an evaluation of the plurality of PSs themselves. Thus, the defectiveness of the various PSs included in different groups is an estimate of their conditions and not a statement of their actual operability conditions. Therefore, a PS included in the defective PS group in stage 3530 is not necessarily defective or inoperable under the plurality of operating conditions indicated in the operating condition data. The determination in stage 3530 is intended to match as accurately as possible the actual actual state of the PDA.

[0363] Step 3540 includes processing the frame information to provide an image representing the frame. The processing is based on the plurality of detection signals of the plurality of PSs of the photodetector but excludes the plurality of PSs not included in the defective PS group. That is, the plurality of detection signals from the plurality of PSs of the PDA are used to generate an image representing the field of view (or other scene, or one or more objects from which light reaches the PDA), but avoiding all detection signals originating from the plurality of PSs that are included in the defective PS group (as described above, which is dynamically determined based on the operating condition data in the relevant frame information captured). Stage 3540 may optionally include calculating a plurality of replacement values to compensate for the plurality of ignored detection signals. Such calculations may include, for example: determining a replacement value for a defective PS based on the plurality of detection signals of a plurality of adjacent PSs. Such calculations may include, for example: determining a replacement value for a pixel of the image based on the plurality of values of a plurality of adjacent pixels of the image. Any technique discussed above regarding image generation in method 2400 may also be used for image generation in stage 3540.

[0364] An example of performing the method for two frames (a first frame and a second frame) may include, for example:

[0365] a. Receive first frame information indicating a plurality of first detection signals provided by a plurality of PSs and related to a first frame duration from the PDA, where the plurality of PSs includes at least a first PS, a second PS, and a third PS. A frame duration is the time for the PDA to aggregate light into a single image or a frame of a video. Different frame durations can be mutually exclusive, but in some embodiments can optionally be partially overlapped.

[0366] b. Receive first operating condition data indicating the operating conditions of the PDA during the first frame duration.

[0367] c. Determine a first defective PS group based at least on the first operating condition data, including the third PS but excluding the first PS and the second PS. The determination can include: directly determining the first defective PS group, or determining other data that implies which pixels are considered defective (such as determining a complement of non-defective pixels, assigning a defect level to each pixel, and then setting a threshold or other determination criteria).

[0368] d. Process the first frame information based on the first defective PS group to provide a first image, such that the processing is at least based on the plurality of first detection signals of the first PS and the second PS (optionally, after previous preprocessing, such as digitization, capping, level adjustment, etc.), and ignores information related to the plurality of detection signals of the third PS.

[0369] e. Receive second frame information indicating a plurality of second detection signals provided by a plurality of detection PSs from the PDA. The second frame information is related to a second frame duration other than the first frame duration.

[0370] f. Receive second operating condition data indicating the operating conditions of the PDA during the second frame duration, where the second operating condition data is different from the first operating condition data. It should be noted that the second operating condition data can be received from the same source as the first operating condition data, but this is not necessary.

[0371] g. Determine data for a second defective PS group based on the plurality of second operating conditions, including the second PS and the third PS but excluding the first PS. The determination can include: directly determining the second defective PS group, or determining other data that implies which pixels are considered defective (such as determining a complement of non-defective pixels, assigning a defect level to each pixel, and then setting a threshold or other determination criteria).

[0372] h. Process the second frame information based on the second defective PS group to provide a second image, such that the processing of the second image information is at least based on the plurality of second detection signals of the first PS, and information related to the plurality of detection signals of the second PS and the third PS is ignored.

[0373] Figure 28A Illustrated is a system 3600 and a plurality of exemplary target objects 3902 and 3904 in accordance with various examples of the presently disclosed subject matter. The EO system 3600 includes at least a processor 3620 operable to process a plurality of detection signals from at least one PDA (which may or may not be part of the same system) to generate a plurality of images representative of a plurality of objects in a field of view of the system 3600. The system 3600 may be implemented by a system 2300 and use similar reference numerals (e.g., in such a case, PDA 3610 may be PDA 2302, controller 3640 may be controller 2314, and so on), but this is not necessary. For the sake of brevity, not all of the descriptions provided above regarding the system 2300 are repeated, and it should be noted that any combination of one or more components of the system 2300 may be implemented analogously in the system 3600 and vice versa. The system 3600 may be a processing system (e.g., a computer, a graphics processing unit) or an EO system further including a PDA 3610 and optics. In the latter case, the system 3600 may be any type of EO system that uses a PDA for detection, such as a camera, a spectrometer, a LIDAR, and the like. Optionally, the system 3600 may include one or more illumination sources 3650 (e.g., a plurality of lasers, a plurality of LEDs) for illuminating the plurality of objects in the FOV (e.g., illuminating the objects for at least the first FET and the second FET). Optionally, the system 3600 may include a controller 3640 operable to determine different FETs for different frames based on different illumination levels of the plurality of objects in the field of view of the EO system. Optionally, those different FETs may include the first FET and / or the second FET.

[0374] In Figure 28A are shown two exemplary targets: a dark-colored car 3902 with a highly reflective license plate (having a body panel with a low reflectivity), and a black rectangular panel 3904 with a white patch thereon. It should be noted that the system 3600 is not limited to generating a plurality of images of a plurality of low-reflectivity objects with a plurality of highly reflective patches. However, the manner in which the system 3600 generates a plurality of images of such targets is interesting.

[0375] The processor 3620 is configured to receive multiple detection results of an object from a PDA (such as PDA 3610 if implemented), where the object includes a high-reflectivity surface (exemplified by multiple targets 3902 and 3904) surrounded by multiple low-reflectivity surfaces on all sides. The multiple detection results include: (a) first-frame information of the object detected by the PDA in a first FET, and (b) second-frame information of the object detected by the PDA in a second FET that is longer than the first FET. The first-frame information and the second-frame information indicate multiple detection signals output by different PSs of the PDA, and the multiple detection signals in turn indicate multiple light intensities of different parts of the target detected by the PDA. Some PSs detect light from the low-reflectivity parts of the multiple objects, while at least another PS detects light from the high-reflectivity surface.

[0376] Based on different FETs, the processor 3620 processes the first-frame information and the second-frame information in different ways. Figure 28B Exemplary first images and second images of multiple targets 3902 and 3904 illustrating various examples according to the presently disclosed subject matter are shown. When processing the first-frame information, the processor 3620 processes the first-frame information based on the first FET. It generates a first image that includes a bright region representing the high-reflectivity surface, which is surrounded by a dark background representing the low-reflectivity surface. This is Figure 28B illustrated as multiple first images 3912 and 3914 (corresponding to Figure 28A the multiple objects 3902 and 3904). When the processor 3620 processes the second-frame information, which is longer than the first FET, based on the second FET. Tt generates a second image that includes a dark background without a bright region. This is Figure 28B illustrated as multiple second images 3922 and 3924 (corresponding to Figure 28A the multiple objects 3902 and 3904).

[0377] That is, even if more light from the highly reflective surface reaches each PS of the photodetector of the second frame, the image output will not be brighter or saturated, but darker. The processor 3620 can use the information of adjacent PSs to determine the darker color of the plurality of pixels representing the highly reflective surface in the second image (which have a plurality of lower-intensity signals because they capture the lower-reflectivity surface of the object), since it determines that the plurality of signals from the plurality of relevant PSs are not available in that longer second FET. Optionally, the processor 3620 can be configured to discard the detected plurality of optical signals corresponding to the highly reflective surface when generating the second image based on the second FET (and optionally also based on the availability modeling of each PS, such as as discussed regarding method 2500), and be configured to calculate a dark color for at least one corresponding pixel of the second image in response to the plurality of light intensities detected from the plurality of adjacent lower-reflectivity surfaces of the plurality of objects captured from the plurality of adjacent PSs. Optionally, the decision by the processor 3620 to discard the information of the corresponding PS is not based on the detected signal level, but on the sensitivity of the corresponding PS to dark current (such as limited capacitance). Optionally, when processing the second frame information, the processor 3620 can identify at least one PS that detects light from the highly reflective surface as not available for the second frame based on the second FET, for example similar to the plurality of identification stages of method 2400.

[0378] It should be noted that the highly reflective surface can be smaller than the low-reflective surface and can be surrounded by the low-reflective surface on all sides, but this is not necessary. The size (such as angular size) of the highly reflective surface can correspond to a single PS, less than one PS, but can also correspond to several PSs. The difference between the high-reflectivity level and the low-reflectivity level can vary. For example: the reflectivity of the low-reflective surface can be between 0% and 15%, while the reflectivity of the highly reflective surface can be between 80% and 100%. In another example, the low-reflective surface can have a reflectivity between 50% and 55%, while the highly reflective surface can be between 65% and 70% in reflectivity. For example: the minimum reflectivity of the highly reflective surface can be ×2, ×3, ×5, ×10, or ×100 of the maximum reflectivity of the low-reflective surface. Optionally, the highly reflective surface has a reflectivity greater than 95% (such as a white surface) within the spectral range detectable by the plurality of PSs, while the low-reflective surface has a reflectivity less than 5% (such as a black surface) within the spectral range detectable by the plurality of PSs. It should be noted that, as described above, one FET can correspond to a fragmented time span (such as corresponding to several illumination pulses) or a single continuous time span.

[0379] It should be noted that, optionally, the amount of the plurality of optical signal levels reaching the relevant PS from the high-reflectivity surface in the first FET and in the second FET may be similar. This can be achieved by filtering the incoming light and correspondingly changing the f-number of the detection optics 3670 (for example, increasing the FET by a factor q and increasing the f-number by a factor q). Optionally, a first exposure value (EV) of the PDA in capturing the first frame information differs from the second EV of the PDA in capturing the second frame information by less than 1%. Optionally, the difference in the FET is the only major difference between the operating conditions between the first frame and the second frame.

[0380] As discussed above, the temperature of the PDA is evaluated to calibrate the availability model to different levels of dark current. Optionally, the processor 3620 may further be configured to: (a) process the detection signal reflected from the object to determine a first temperature evaluation of the photoelectric detection array in capturing the first frame information and a second temperature evaluation of the photoelectric detection array in capturing the first frame information, and (b) determine to discard a plurality of detection results corresponding to the high-reflectivity surface based on the second FET and the second temperature evaluation.

[0381] Figure 29 FIG. is a flowchart of a method 3700 for generating image information based on data of a PDA, showing various examples of the subject matter according to the present disclosure. Referring to the examples described with respect to the previous figures, it should be noted that the method 3700 may optionally be executed by the system 3600. Any variations discussed above with respect to the system 3600 may be applied mutatis mutandis to the method 3700. In particular, the method 3700 (and at least its various stages 3710, 3720, 3730, and 3740) may be executed by the processor 3620.

[0382] Stage 3710 includes receiving, from the PDA, first frame information including a black target with a white area, the first frame information indicating the light intensity of different parts of the target detected by the PDA in a first FET. It should be noted that the white area may be replaced by a bright area (or other highly reflective area). For example, any area with a reflectivity higher than 50% may be used instead. It should be noted that the black target may be replaced by a dark area (or other slightly reflective area). For example, any target with a reflectivity lower than 10% may be used instead.

[0383] Stage 3720 includes processing the first frame information based on the first FET to provide a first image, the first image including a bright area surrounded by a dark background. Optionally, any of the image generation processes discussed above with respect to any of stages 2406, 2414, and 2422 of method 2400 may be used to implement stage 3720.

[0384] Stage 3730 includes receiving a second frame of information of a black target including white areas from the PDA, the second frame of information being indicative of multiple light intensities of different portions of the target detected by the PDA in a second FET that is longer than the first FET.

[0385] Step 3740 includes processing the second frame information based on the second FET to provide a second image, the second image including a dark background without a bright area. Optionally, stage 3740 can be implemented using any of the image generation processes discussed above with respect to any of steps 2406, 2414, and 2422 of method 2400 and the previous stage of identifying multiple available and unavailable PS groups.

[0386] Regarding the execution order of method 3700, stage 3720 is executed after stage 3710, and stage 3740 is executed after stage 3730. In addition, any suitable stage order may be used. Method 3700 may also optionally include capturing the first frame information and / or the second frame information via a PDA.

[0387] Optionally, after receiving the first frame information, the second FET may be determined before receiving the second frame information, the second FET being longer than the first FET. Optionally, the processing of the second frame information may include: based on the second FET, discarding the light intensity information of the detected white area; determining a dark color of at least one corresponding pixel of the second image in response to a plurality of light intensities of a plurality of adjacent areas detected by the second frame information. Optionally, the processing of the second frame information may include: based on the second FET, identifying at least one PS, the at least one PS detecting light from the white area as unavailable for the second frame. Optionally, a first exposure value (EV) of the PDA in capturing the first frame information may differ by less than 1% from a second EV of the PDA in capturing the second frame information.

[0388] Optionally, during the first frame exposure time, the dark current on the PS associated with the low reflectivity data accumulates to leave an available dynamic range for the PS, while during the second frame exposure time, the dark current on that PS accumulates to leave an insufficient dynamic range for the PS. In such a case, the PS corresponding to the high reflectivity region cannot be used for image generation in the second image, and replacement color values can be calculated to replace the lost detection levels.

[0389] A non - transitory computer - readable medium is provided for generating image information based on data of a PDA (including a plurality of instructions stored thereon), which when executed on a processor, will perform the following steps: (a) receiving, from a PDA, first - frame information of a black target including a white area, the first - frame information indicating light intensities of different parts of the target detected by the PDA in a first FET; (b) processing the first - frame information based on the first FET to provide a first image including a bright area surrounded by a dark background; (c) receiving, from the PDA, second - frame information of the black target including the white area, the second - frame information indicating light intensities of different parts of the target detected by the PDA in a second FET longer than the first FET; (d) processing the second - frame information based on the second FET to provide a second image including a dark background without a bright area.

[0390] The non - transitory computer - readable medium of the preceding paragraph may include: other instructions stored thereon, which when the plurality of instructions are executed on a processor, perform any other steps or variations discussed above regarding method 3700.

[0391] In the foregoing disclosure, multiple systems, methods, and computer code products are described, and ways of using them to optically capture and generate high-quality images are described. In particular, in the presence of high PD dark current, such systems, methods, and computer code products can be utilized to generate multiple high-quality SWIR images (or other SWIR sensing data). Such PDs can be germanium PDs in many cases, but not in all cases. Some ways of using such systems, methods, and computer program products in a synergistic manner are discussed above, and many other ways are possible and are considered part of the innovative subject matter of this disclosure. Any of the systems discussed above can incorporate any one or more components of any one or more of the other systems discussed above to achieve higher-quality results, in a more efficient or cost-effective manner, or to obtain similar results for any other reason. Similarly, any of the methods discussed above can incorporate any one or more stages of any one or more of the other methods discussed above to achieve higher-quality results, to achieve similar results in a more efficient or cost-effective manner, or for any other reason.

[0392] In the paragraphs below, some non-limiting examples of such combinations are provided to demonstrate certain possible synergies.

[0393] For example: Imaging systems 100, 100', and 100" in which the integration time is short enough to overcome the excessive influence of dark current noise can implement multiple PDDs, such as multiple PDDs 1300, 1300', 1600, 1600', 1700, 1800, which are included in the receiver 110 to reduce the non-time-varying (direct current, DC) portion of the dark noise. In this way, the capacitances of the multiple PSs are not overwhelmed by the non-time-varying portion of the dark current that is not accumulated in the detection signal, and the noise of the dark current does not obscure the detection signal. Implementing any one of the multiple PDDs 1300, 1300', 1600, 1600', 1700, 1800 in any of the multiple imaging systems 100, 100', and 100" can be used to extend the frame exposure time to a significant extent (since the DC portion of the dark current is not accumulated in the capacitance), while still detecting a meaningful signal.

[0394] For example, imaging systems 100, 100', and 100" in which the integration time is set short enough to overcome the excessive influence of dark current noise can implement any one or more of methods 2400, 2500, and 3500 to determine the multiple PSs available at that frame exposure time and may reduce the frame exposure time (which corresponds to the integration time) to further determine that a sufficient number of PSs are available. Similarly, the expected ratio between the read noise of a given FET and the expected cumulative dark current noise level and the expected availability of different PSs in such a PS can be used by the controller to set a balance between the quality of the detected signal, the number of available pixels, and the illumination level required by the light source (such as laser 600). When applicable, the availability models for different FETs can also be used to determine the distance of the multiple gated images generated by imaging systems 100, 100', and 100". Incorporating any one of the multiple PDDs 1300, 1300', 1600, 1600', 1700, 1800 further as the sensor of such an imaging system will increase the benefits discussed in the previous section.

[0395] For example, any one or more of methods 2400, 2500, and 3500 can be implemented by system 1900 (or by any EO system including any one of the multiple PDDs 1300, 1300', 1600, 1600', 1700, 1800). The reduction of the many effects of the dark current accumulation as discussed with respect to system 1900 (or any of the PDDs mentioned) allows for the utilization of many longer FETs. Implementing any one of the methods can be used to facilitate longer FETs because determining which PSs are temporarily unavailable in a relatively long FET enables system 1900 (or another EO system with one of the multiple PDDs mentioned) to ignore these PSs and optionally replace their detection outputs with data from multiple adjacent PSs.

[0396] Certain stages of the foregoing methods can also be implemented in a computer program running on a computer system, the computer program including at least code portions for performing the many steps of the relevant methods when running or enabling a programmable device on a programmable device such as a computer system to perform the many functions of a device or system according to the present disclosure. Such a method can also be implemented in a computer program running on a computer system, the computer program including at least code portions that cause a computer to perform the many steps of a method according to the present disclosure.

[0397] A computer program is a list of instructions, such as a specific application program and / or an operating system. The computer program may for example include one or more of the following: a subroutine, a function, a procedure, a method, an implementation, an executable application, an applet, a service program, a source code, a code, a shared library / dynamic loading library, and / or other instruction sequences designed to be executed on a computer system.

[0398] The computer program may be internally stored on a non-transitory computer-readable medium. All or some of the computer program may be provided on a computer-readable medium that is permanently, removably, or remotely coupled to an information processing system. The computer-readable medium may include, for example but not limited to, any of the following: magnetic storage media, including disk and tape storage media; optical storage media, such as optical disc media (such as CD-ROM, CD-R, etc.) and digital video disc storage media; non-volatile storage media, including semiconductor-based storage cells, such as flash memory, EEPROM, EPROM, ROM; ferromagnetic digital memories; MRAM; volatile storage media, including registers, buffers, or caches, main memory, RAM, etc.

[0399] A computer process generally includes an executing (running) program or a part of a program, current program values and status information, and is used by the operating system to manage the execution of the process. An operating system (OS) is software that manages the sharing of a computer's resources and provides an interface for programmers to access these resources. The operating system processes system data and user input and responds by allocating and managing tasks and internal system resources as a service to the system's users and programs.

[0400] The computer system may for example include at least one processing unit, associated memory, and multiple input / output (I / O) devices. When the computer program is executed, the computer system processes information according to the computer program and generates result output information via the I / O devices.

[0401] The various connections discussed herein can be any type of connection suitable for transmitting signals to or from various nodes, units, or devices, for example, via various intermediate devices. Thus, unless otherwise implied or stated, the various connections can be, for example, direct or indirect connections. The various connections can be illustrated or described with reference to a single connection, multiple connections, unidirectional connections, or bidirectional connections. However, different embodiments can vary the implementation of the various connections. For example: a single unidirectional connection can be used instead of a bidirectional connection, and vice versa. Also, multiple connections can be replaced with a single connection that transmits multiple signals serially or in a time-multiplexed manner. Similarly, the various single connections carrying multiple signals can be separated into various different connections carrying subsets of these signals. Thus, there are many options for transmitting signals.

[0402] Optionally, the illustrated examples can be implemented as circuits located on a single integrated circuit or within the same device. Alternatively, the examples can be implemented as any number of separate integrated circuits or separate devices interconnected in a suitable manner. Optionally, an appropriate portion of the various methods can be implemented as a soft or code representation of a physical circuit or a logical representation convertible to a physical circuit, such as in any suitable type of a hardware description language.

[0403] Other modifications, variations, and alternatives are possible. Thus, the specification and drawings are to be regarded as illustrative rather than restrictive. Although certain features of the present disclosure have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. Thus, it is to be understood that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the present disclosure. It is to be understood that the above embodiments are cited only as examples, and that various features thereof, as well as combinations of these features, can be changed and modified. Although the various embodiments have been shown and described, it should be understood that it is not the intention of such disclosure to limit the present disclosure, but rather to cover all modifications and alternative constructions that fall within the scope of the present disclosure, as defined in the appended claims.

[0404] In the claims or specification of the present application, unless otherwise specified, adjectives such as "substantially" and "about" modifying a conditional or relational characteristic of one or more features of an embodiment are understood to mean that the condition or characteristic is defined within an acceptable tolerance range for the operation of the embodiment for a contemplated application. It should be understood that in the case of a reference to "a" or "an" element in the claims or specification, such reference should not be construed as meaning only one of the elements exists.

[0405] All patent applications, white papers, and other publicly available data issued by the assignee of the present disclosure and / or TriEye LTD. of Tel Aviv, Israel are hereby incorporated by reference in their entirety. References mentioned herein are not admitted to be prior art.

Claims

1. An optoelectronic detection device, characterized in that: Comprising: An active photosensing site, including an active photodiode; A reference photosensing site, including a reference photodiode; A first voltage-controlled current circuit, composed of a voltage-controlled current source or a voltage-controlled current sink, the first voltage-controlled current circuit being coupled to the active photodiode; And A control voltage generation circuit, coupled to the first voltage-controlled current circuit and the reference photosensing site, and configured to provide a control voltage having a voltage level generated in response to the dark current of the reference photodiode to the first voltage-controlled current circuit, so as to reduce the influence of the dark current of the active photodiode on the output of the active photosensing site.

2. The optoelectronic detection device according to claim 1, wherein: The control voltage generation circuit includes an amplifier for providing the control voltage.

3. The optoelectronic detection device according to claim 2, characterized in that: The photodetection device includes a reference voltage-controlled current circuit, the reference voltage-controlled current circuit being composed of a voltage-controlled current source or a voltage-controlled current sink, the reference voltage-controlled current circuit being coupled to the reference photodiode, wherein a first input of the amplifier is supplied with a first input voltage, and wherein a second input of the amplifier is electrically coupled between the reference photodiode and the reference voltage-controlled current circuit.

4. The optoelectronic detection device according to claim 3, wherein: The first voltage-controlled current circuit and the reference voltage-controlled current circuit are coupled to an output of the amplifier, and the amplifier continuously reduces a difference between an output of the reference voltage control circuit and the first input voltage, thereby generating the control voltage.

5. The optoelectronic detection device according to claim 4, characterized in that: The photodetection device includes: A plurality of active photosensing sites, each active photosensing site including an active photodiode, A plurality of reference photosensing sites, each reference photosensing site including a plurality of reference photodiodes, a plurality of first voltage-controlled current circuits, each first voltage-controlled current circuit being coupled to the active photodiode of at least one of the plurality of active photosensing sites, and A plurality of reference voltage-controlled current circuits, each reference voltage-controlled current circuit being coupled to at least one reference photodiode of the plurality of reference photodiodes, Wherein the second input of the amplifier is electrically coupled to each reference photodiode of the plurality of reference photodiodes, and wherein the control voltage is supplied to each first voltage-controlled current circuit of the plurality of first voltage-controlled current circuits.

6. The optoelectronic detection device according to claim 5, wherein: A plurality of different active photodiodes simultaneously generate a plurality of different levels of dark current, wherein a plurality of different reference photodiodes simultaneously generate a plurality of different levels of dark current, and wherein the control voltage generation circuit provides a same control voltage to the plurality of different active photodiodes based on an average of the plurality of different dark currents of the plurality of reference photodiodes.

7. The optoelectronic detection device according to claim 1, wherein: The photoelectric detection device includes a plurality of first voltage-controlled current circuits, the plurality of first voltage-controlled current circuits including at least one voltage-controlled current source and at least one voltage-controlled current sink, the at least one voltage-controlled current source being commonly coupled to each of a plurality of active photosensitive sites, and the at least one voltage-controlled current sink being commonly coupled to each of the plurality of active photosensitive sites; Wherein the control voltage generation circuit includes: A first amplifier, coupled to the at least one voltage-controlled current source, for providing a first control voltage to the plurality of active photosensitive sites at a first time, A second amplifier, coupled to the at least one voltage-controlled current sink, for providing a second control voltage to the plurality of active photosensitive sites at a second time, and A switching circuit for selecting between providing the first control voltage and providing the second control voltage.

8. The optoelectronic detection device according to claim 3, wherein: The photoelectric detection device further includes a controller for providing the first input voltage, wherein the first input voltage has a level determined to correspond to a bias voltage on the active photodiode.

9. The optoelectronic detection device according to claim 1, characterized in that: The photoelectric detection device further includes a physical barrier that prevents light from a field of view of the photoelectric detection device from reaching a plurality of reference photodiodes.

10. The optoelectronic detection device according to claim 1, characterized in that: The photoelectric detection device further includes: A plurality of active photosensitive sites, each active photosensitive site including an active photodiode, A plurality of reference photosensitive sites, each reference photosensitive site including a plurality of reference photodiodes, a plurality of first voltage-controlled current circuits, each first voltage-controlled current circuit being coupled to the active photodiode of at least one of the plurality of active photosensitive sites, and A plurality of reference voltage-controlled current circuits, each reference voltage-controlled current circuit being coupled to at least one reference photodiode of the plurality of reference photodiodes, Wherein when the photoelectric detection device operates at a first temperature, the control voltage generation circuit provides a first control voltage to the first voltage-controlled current circuit to provide a current at a first level in response to the dark currents of the plurality of reference photodiodes to reduce the influence of the dark currents of the plurality of active photodiodes on the output of the plurality of active photosensitive sites; Wherein when the photoelectric detection device operates at a second temperature higher than the first temperature, the control voltage generation circuit provides a second control voltage to the first voltage-controlled current circuit to provide a current at a second level in response to the dark currents of the plurality of reference photodiodes to reduce the influence of the dark currents of the plurality of active photodiodes on the output of the plurality of active photosensitive sites, and wherein the second level is greater in magnitude than the first level.

11. The optoelectronic detection device according to claim 1, characterized in that: The photoelectric detection device further includes: A plurality of active photosensitive sites, each active photosensitive site including an active photodiode; A plurality of reference photosensitive sites, each reference photosensitive site including a plurality of reference photodiodes; Multiple first voltage-controlled current circuits, each first voltage-controlled current circuit being coupled to the active photodiode of at least one of the multiple active photosensing sites; Multiple reference voltage-controlled current circuits, each reference voltage-controlled current circuit being coupled to at least one reference photodiode of the multiple reference photodiodes; An optical device for guiding light from a field of view of the photodetector to the multiple active photosensing sites; A power supply for supplying power to the multiple active photosensing sites, the multiple reference photosensing sites, and an amplifier; A readout circuit for providing detection information in response to multiple detection signals of the multiple active photosensing sites; A processor for processing the detection information to provide an image of at least an object in the field of view; and A memory module for storing at least one of the detection information and the multiple detection signals.

12. A method for reducing the influence of dark current in a photoelectric detection device, characterized in that: The method includes: when the photodetector operates at a first temperature: Determining a first control voltage based on the dark current of at least one reference photodiode of the photodetector; Providing the first control voltage to a first voltage-controlled current circuit, the first voltage-controlled current circuit being coupled to at least one active photodiode of an active photosensing site of the photodetector, thereby causing the first voltage-controlled current circuit to apply a first dark current rejection current in the active photosensing site; Generating a first detection current by the active photodiode in response to: (a) light impinging on the active photodiode from an object in a field of view of the photodetector, and (b) the dark current generated by the active photodiode; Outputting a first detection signal from the active photosensing site, the amplitude of the first detection signal being less than the first detection current, in response to the first detection current and the first dark current rejection current, thereby compensating for the influence of the dark current on the first detection signal; and when the photodetector operates at a second temperature that is at least 10 degrees Celsius higher than the first temperature, Determining a second control voltage based on the dark current of at least one reference photodiode of the photodetector; Providing the second control voltage to the first voltage-controlled current circuit, thereby causing the first voltage-controlled current circuit to apply a second dark current rejection current in the active photosensing site; generating a second detection current by the active photodiode in response to light from the object impinging on the active photodiode and the dark current generated by the active photodiode; and Outputting a second detection signal from the active photosensing site, the amplitude of the second detection signal being less than the second detection current, in response to the second detection current and the second dark current rejection current, thereby compensating for the influence of the dark current on the second detection signal, wherein an amplitude of the second dark current rejection current is at least twice as large as an amplitude of the first dark current rejection current by a factor.

13. The method according to claim 12, wherein: A first level of radiation impinging on the active photodiode from the object during a first time period in which the first dark current suppression current is generated is substantially equal to a second level of radiation impinging on the active photodiode from the object during a second time period in which the second dark current suppression current is generated, wherein an amplitude of the second detection signal is substantially equal to an amplitude of the first detection signal.

14. The method according to claim 12, wherein: The determination of the first control voltage and the determination of the second control voltage are performed by a control voltage generation circuit including at least one amplifier having an input electrically coupled between the reference photodiode and a reference voltage controlled current circuit coupled to the reference photodiode.

15. The method according to claim 14, characterized in that: The method further includes supplying a first input voltage to another input of the amplifier, the level of the first input voltage being determined to correspond to a bias voltage on the active photodiode.

16. The method according to claim 15, wherein: The supplying includes supplying the first input voltage such that a bias voltage on the reference photodiode is substantially the same as a bias voltage on the active photodiode.

17. The method according to claim 16, wherein: The method includes, when the plurality of active photodiodes also have a plurality of different dark currents, determining the first control voltage and the second control voltage based on the plurality of different dark currents of the plurality of reference photodiodes of the photodetector device, wherein the providing of the first control voltage includes providing the same first control voltage to a plurality of first voltage controlled current circuits, each first voltage controlled current circuit being coupled to at least one of the plurality of active photodiodes of the photodetector device having a plurality of different dark currents, and wherein the providing of the second control voltage includes providing the same second control voltage to the plurality of first voltage controlled current circuits.

18. A method for testing an optoelectronic detection device, characterized in that: The method includes: Providing a first voltage to a first input of an amplifier of a control voltage generation circuit, wherein a second input of the amplifier is coupled to a reference photodiode and a second current circuit that supplies a current determined to be at a level in response to an output voltage of the amplifier, thereby causing the amplifier to generate a first control voltage for a first current circuit of a photosensitive site of the photodetector device; Reading a first output signal of the photosensitive site, the first output signal being generated in response to the current generated by the first current circuit; Providing a second voltage different from the first voltage to the first input of the amplifier, thereby causing the amplifier to generate a second control voltage for the first current circuit; Reading a second output signal of the photosensitive site, the second output signal being generated in response to the current generated by the first current circuit; and Determining a defect state of a detection path of the photodetector device based on the first output signal and the second output signal, the detection path including the photosensitive site and a readout circuit associated with the photosensitive site.

19. The method according to claim 18, wherein: The method further includes reading at least two output signals from each of a plurality of photosensitive sites of the photodetector device, the at least two output signals being responsive to at least two different voltages of respective amplifiers provided to each of the plurality of photosensitive sites, determining an operating state for at least one first detection path based on the at least two output signals output by at least one photosensitive site associated with a respective first detection path, and determining a fault state for at least one second detection path based on the at least two output signals output by at least one other photosensitive site associated with a respective second detection path.

20. The method according to claim 19, characterized in that: The first voltage causes the amplifier to generate a first control voltage, the first control voltage causing the first current circuit to saturate the photosensitive site; wherein the determination of the defective state includes determining that the detection path is faulty in response to determining that the first output signal is not saturated.

21. The method according to claim 20, wherein: During a first detection frame of the photodetector device, the reading of the first output signal is performed while the photosensitive site is exposed to ambient light, wherein after previously determining that the detection path is operable, the determination of the fault state is performed in response to reading a saturated output signal in a second detection frame, the second detection frame being earlier than the first detection frame.

22. The method according to claim 19, wherein: The second voltage causes the amplifier to generate a second control voltage, the second control voltage causing the first current circuit to consume a detection signal caused by light impinging on the field of view at the photosensitive site, wherein the determination of the defective state includes determining that the detection path is faulty in response to determining that the second output signal is not consumed.

23. The method according to claim 22, characterized in that: During a third detection frame of the photodetector device, the reading of the second output signal is performed while the photosensitive site is exposed to ambient light, wherein after previously determining that the detection path is operable, the determination of the fault state is performed in response to reading a consumed output signal in a fourth detection frame, the fourth detection frame being earlier than the third detection frame.

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