Automatic abnormal pixel detection

Abstract

A method and system (118) for automatic abnormal pixel detection of at least one photodetector (120) is disclosed. The photodetector (120) comprises a plurality of pixels (122), where each pixel (122) comprises at least one photosensitive area (124), where each pixel (122) is configured to generate a signal in response to an optical radiation illuminating a respective photosensitive area (124) of the pixel, where the photodetector (120) further comprises at least one readout circuit (126), where the readout circuit (126) is configured to sense the signal in response to the optical radiation illuminating the respective photosensitive area (124) of the pixel. The at least one readout circuit is configured to read out the plurality of pixels (122). The method comprises the steps of: a) applying a skimming voltage V < skimming > to each pixel (122) of the plurality of pixels (122) and measuring an initial signal value S < initial > for each pixel (122) of the plurality of pixels (122) by using a readout circuit (126) of the photodetector (120) without illuminating the photodetector (120); b) changing a skimming voltage V < skimming, j > of at least one pixel j (130) of the plurality of pixels (122) and measuring an actual signal value S < actual, k > of at least one further pixel k (132) of the plurality of pixels (122), where k is not equal to j; c) comparing the initial signal value of the further pixel k (132) with the actual signal value of the further pixel k (132) by using at least one processor (134), where the further pixel k (132) is detected as an abnormal pixel (116) if the initial signal value differs from the actual signal value by more than at least one predefined tolerance.

Description

Technical Field

[0001] This invention relates to a method and system for automatically detecting abnormal pixels in at least one photodetector comprising multiple pixels. The invention further relates to a computer program and a computer-readable storage medium for performing the method. Such methods and apparatus are generally used for testing and / or preparing photodetectors for research or monitoring purposes, particularly in the infrared (IR) spectral region, especially in the near-infrared (NIR) spectral region, for example, for detecting heat, flames, fires, or smoke. However, other types of applications are also possible. Background Technology

[0002] Photodetectors with multiple pixels arranged in an array or matrix can be used in optical research or monitoring. Errors or inaccuracies during the manufacture of these photodetectors can cause neighboring pixels to provide inappropriate signals, for example, due to unwanted electrical or optical connections, or instability of the electrical or optical properties of the corresponding pixels over time or under environmental conditions (such as temperature). Typically, optical setups can be used to identify these pixels in order to generate and analyze spectral measurements.

[0003] US 6,118,482 A describes a method and apparatus for electrical testing of a CMOS pixel sensor, the method and apparatus relating to electrically writing a pattern into the CMOS pixel sensor for detecting short circuits or jamming faults in adjacent cells and verifying the functionality and performance of readout channel circuitry.

[0004] US 2008 / 0106602 A1 discloses an on-chip testing method for determining photon transfer curves (PTC) and dark current in an image sensor. The method includes a snapshot mode in which a first plurality of pixel rows are exposed for time t1, a second plurality of pixel rows for time t2, and so on, until the nth plurality of pixel rows are exposed for time t... n Up to this point, the total number of pixel rows is equal to one frame and t n >t2>t1. The resulting image has "n" regions, each with a different brightness, which gradually become brighter from the top to the bottom of the image.

[0005] US 2005 / 0041242 A1 describes methods and apparatus for testing image sensors. These apparatuses include image sensor test equipment comprising a digital light projection system capable of projecting a static or dynamic image onto an image sensing device under test, and an image sensor signal detection device for analyzing the output of the image sensing device under test. The digital light projection system includes a light source, collimating optics, a digital micromirror device, and a focusing optics. Other example methods and apparatus include image sensor test equipment employing a digital light projection system capable of simultaneously testing multiple image sensors. The light source is calibrated using a digital micromirror device and converted into a desired test image. The test image is then focused onto an image sensor, the output of which is read by a detector and correlated with the input digital test image.

[0006] US 6,489,798 B1 discloses a method and apparatus for testing an image sensor array (e.g., a CMOS imager) having sensing circuitry arranged in rows and columns, wherein the sensing circuitry includes photosensitive devices. A reset voltage is applied to the photosensitive device in each sensor circuit such that at least adjacent circuits are reset to different voltage levels. The voltage on each photosensitive device is detected and compared to a desired level to determine the presence of any faults in the sensing circuitry or lines in the array and the location where a fault might occur. Different reset voltages can be applied to each of these sensor circuits; however, in one embodiment, a power supply with only two voltage levels can be used. One voltage level is applied to the second column of every two columns to provide a power supply voltage to the photosensitive devices and is applied to the second row of every two rows to generate a reset enable signal for the photosensitive devices. A second voltage level is applied to the remaining columns and rows, thereby generating different reset voltage levels on adjacent sensing circuits.

[0007] JP 2000 244005 A describes a phototransfer device. By injecting charge carriers of the same type as those generated by the projected light, a correct signal is output shortly after the power is turned on in the phototransfer device. Immediately after the power is turned on in the phototransfer device with pixels, the potential at the terminals is raised to a level significantly higher than the reference voltage at the terminals, causing the diode to be forward biased and the phototransistor to be turned on. Thereafter, the potential at the terminals is lowered. Charge carriers of the same type as those generated by the light, injected from the diode into the phototransistor of the phototransfer element, immediately discharge through the forward bias current of the diode, thereby bringing the base of the phototransistor to a quiescent state, where the base current is equal to the current generated by the light. By injecting charge carriers into the pixels, the output instability when the power is turned on in the phototransfer device can be eliminated shortly, thus obtaining a correct output.

[0008] EP 3 637 135 A1 discloses a solid-state optical receiver system, particularly for automotive applications, comprising at least two optical receiver circuits, each including an optical receiver for detecting an optical input signal and a signal processing unit for processing the signal from the optical receiver. The solid-state optical receiver system is characterized by including a short-circuit detection unit for detecting short circuits between the optical receiver circuits. A method for detecting short circuits between optical receiver circuits in a solid-state optical receiver system, particularly for automotive applications, is further described.

[0009] Despite the numerous advantages achieved by known methods and apparatus, several technical challenges remain. Specifically, generating, analyzing, and verifying spectral measurements of a fabricated photodetector may only be possible in the later stages of manufacturing. For example, during manufacturing, photodetectors typically cannot measure any spectral information without additional hardware setups such as optical filters, like linearly variable filters (LVFs) or gratings. Therefore, inspecting defective or anomalous pixels in the early stages of manufacturing may only be achievable in a limited way and with considerable effort, such as by mechanically contacting the pixels with the wafer detector to perform resistance measurements. Resistance measurements can typically be performed before readout electronics are bonded to the photodetector. However, short circuits are particularly likely to occur after bonding. Furthermore, spectral measurements may require additional hardware setups. For example, an LVF can be used to break down light generated by an additional light source into spectral components on the pixels. Defective or anomalous pixels can only be reliably located by measuring the spectrum with a dynamic range. Therefore, in summary, there is a need to utilize the array itself and not use optical signals, specifically not spectral measurements, to inspect photodetectors with multiple pixels. The problem to be solved

[0010] Therefore, it is desirable to provide methods and apparatus that at least partially address the aforementioned technical challenges. Specifically, a method and system for automatically detecting anomalous pixels on at least one photodetector should be proposed, which enables the detection of anomalous pixels at any early stage of manufacturing without the need for additional hardware setup. Summary of the Invention

[0011] This problem is solved by a method and system for automatically detecting abnormal pixels in at least one photodetector, having the features of the independent claims. Advantageous embodiments that can be implemented independently or in any arbitrary combination are set forth in the dependent claims and throughout the specification.

[0012] In a first aspect of the invention, a method for automatically detecting abnormal pixels in at least one photodetector comprising a plurality of pixels is disclosed. Each pixel includes at least one photosensitive region. Each pixel is configured to generate a signal in response to optical radiation illuminating a corresponding photosensitive region of the pixel. The photodetector further includes at least one readout circuit configured to read out the plurality of pixels.

[0013] As used herein, the term "photodetector" is a broad term and will be given its common and conventional meaning to those skilled in the art, and is not limited to a specific or custom meaning. Specifically, the term may refer to, but is not limited to, an optical detector or optical sensor configured to detect optical radiation, such as for detecting light irradiation and / or a light spot generated by at least one light beam. A photodetector may be specifically configured to detect optical radiation in one or more of the visible, infrared, and ultraviolet spectral ranges. The pixels of a photodetector may respond to incident illumination and may be configured to generate an electrical signal indicating the intensity of the illumination, such as a detector current. A photodetector may be sensitive in one or more of the visible, ultraviolet, or infrared spectral ranges (specifically, the near-infrared (NIR) spectral range). A photodetector may specifically be an infrared photodetector. The photodetector is sensitive to electromagnetic radiation in the wavelength range of 600 nm to 1000 µm, specifically 760 nm to 15 µm, more specifically 1 µm to 5 µm, and more specifically 1 µm to 3 µm (preferably 1.3 µm to 2.5 µm, more preferably 1.5 µm to 2.2 µm).

[0014] As used herein, the term "pixel" is a broad term and will be given its common and conventional meaning to those skilled in the art, and is not limited to any particular or custom meaning. Specifically, the term may refer to, but is not limited to, a single optical detection or sensing device configured for detecting optical radiation. Specifically, a pixel may be a single unit of a photodetector configured for being illuminated by light. A pixel may be configured to receive optical radiation and to generate at least one output signal, such as an electronic signal (e.g., detector current), in response to illumination by optical radiation. A pixel may be or may include a single photosensitive element. A pixel may have at least one photosensitive characteristic such that illumination of the pixel causes at least one change in the photosensitive characteristic.

[0015] As used herein, the term "light" (also referred to as "optical radiation") refers to, but is not limited to, a region of electromagnetic radiation, commonly referred to as the "optical spectral range," and includes one or more of the visible, ultraviolet, and infrared spectral ranges. The term "ultraviolet spectrum" or "UV" generally refers to electromagnetic radiation with wavelengths from 1 nm to 380 nm, preferably from 100 nm to 380 nm. The term "visible" generally refers to wavelengths from 380 nm to 760 nm. The term "infrared" or "IR" generally refers to wavelengths from 760 nm to 1000 µm, wherein wavelengths from 760 nm to 3 µm are generally referred to as "near-infrared" or "NIR," while wavelengths from 3 µm to 15 µm are generally referred to as "mid-infrared" or "MidIR," and wavelengths from 15 µm to 1000 µm are referred to as "far-infrared" or "FIR."

[0016] As used herein, the term "photosensitive region" is a broad term and will be given its common and conventional meaning to those skilled in the art and is not limited to a specific or custom meaning. The term may specifically refer to, but is not limited to, elements suitable for interacting with optical radiation. A photosensitive region may be located on the surface of a photodetector, specifically on the surface of a pixel of the photodetector. A photosensitive region may specifically be a single, enclosed, and uniform photosensitive region. However, other options may also be feasible. A photosensitive region may form part of a pixel, specifically providing a photosensitive portion of the pixel. The photodetector includes multiple pixels. The multiple pixels, specifically the photosensitive regions of the multiple pixels, may be arranged in at least one of an array or a matrix. For example, the multiple pixels, specifically the photosensitive regions of the multiple pixels, may be arranged in a linear array. As another example, the multiple pixels, specifically the photosensitive regions of the multiple pixels, may be arranged in a 2D distribution. The multiple pixels, specifically the photosensitive regions of the multiple pixels, may be arranged in a pattern. The pattern may be periodic or aperiodic. The pattern may be a rectangular, hexagonal, or other shaped pattern. A pixel may include at least one substrate. A single pixel can be a substrate having at least one single photosensitive region disposed therein or on it, which generates a physical response to light illumination within a given wavelength range. However, other options are also possible.

[0017] The photosensitive region may include at least one photoconductive material. The photoconductive material may be selected from the group consisting of: lead sulfide (PbS); lead selenide (PbSe); mercury cadmium telluride (HgCdTe); cadmium sulfide (CdS); cadmium selenide (CdSe); indium antimonide (InSb); indium arsenide (InAs); indium gallium arsenide (InGaAs); silicon (Si); silicon germanium (SiGe); lithium tantalate (LiTaO3); triglycine sulfate (TGS); platinum silicide (PtSi); quantum well infrared photodetector (QWIP); intrinsic semiconductor; organic semiconductor. For example, the photodetector may be or may include at least one line sensor, which includes a one-dimensional pixel array, such as a CCD line sensor, a CMOS line sensor, etc. For example, the photodetector may be or may include a two-dimensional pixel array, such as a CCD sensor, a CMOS sensor, etc.

[0018] A photodetector may specifically include at least one detector array comprising a plurality of pixels, wherein, optionally, each pixel may be configured to detect at least a portion of at least one constituent wavelength component. The photodetector may include a plurality of pixels arranged in a detector array. For example, a photodetector may include a plurality of pixels arranged in a linear array. Alternatively or additionally, a photodetector may include a plurality of pixels arranged in a two-dimensional array. The detector array, specifically the linear pixel array, may include a number of 2 to 1000 pixels, a number of 10 to 500 pixels, a number of 200 to 300 pixels, and a number of 256 pixels, most specifically. However, other numbers of pixels and / or other arrangements may be feasible.

[0019] As used herein, the term "signal" is a broad term and will be given its common and conventional meaning to those skilled in the art and is not limited to a particular or custom meaning. The term may specifically refer to, but is not limited to, a signal generated by a photodetector. A signal may specifically include at least one output signal of the pixel. The at least one output signal may be at least one electronic signal. The at least one output signal may be an analog signal and / or a digital signal. Output signals of adjacent pixels may be generated simultaneously or in a temporally continuous manner. For example, during row or line scanning, it may be feasible to generate a sequence of output signals corresponding to a series of photosensitive elements that may be arranged in rows. Additionally, each pixel may preferably be an active pixel sensor adapted to amplify the output signal before providing it as a detector signal to an external processor, specifically to a readout circuit. For this purpose, each pixel may include one or more signal processing devices, such as one or more filters and / or analog-to-digital converters, for processing and / or preprocessing the electronic signal. Each pixel may include at least one rejection circuit configured to reject detector current generated from the pixel in response to illumination by optical radiation.

[0020] As outlined above, the signal for each pixel can depend on the illumination of its corresponding photosensitive region by optical radiation. Specifically, the signal can depend on the detector current generated by the corresponding pixel in response to light illumination, for example, at least one photocurrent generated by the corresponding pixel in response to light illumination. A pixel can also be configured to generate a signal even when no optical radiation illuminates its photosensitive region. The signal in the absence of illumination of the photosensitive region can also be referred to as a "dark current signal." The signal, specifically the detector current, can include a dark current signal. The dark current signal can depend on operating parameters applied to the corresponding pixel, such as the applied voltage.

[0021] As used herein, the term "irradiation" is a broad term and will be given its common and conventional meaning to those skilled in the art, and is not limited to any particular or custom meaning. Specifically, the term may refer to, but is not limited to, the amount or intensity of light incident on a region (specifically, the photosensitive area of ​​a pixel).

[0022] As outlined above, the photodetector further includes at least one readout circuit configured to read out a plurality of pixels. As used herein, the term "readout" is a broad term and will be given its common and conventional meaning to those skilled in the art and is not limited to a specific or custom meaning. Specifically, the term may refer to, but is not limited to, the action or process of quantifying and / or processing at least one physical characteristic and / or a change in at least one physical characteristic detected by at least one device (specifically, by the at least one photodetector, or more specifically, by a photosensitive region). Readout may include individual readout of a single device, such as individual readout of a photosensitive region of each pixel. Additionally or alternatively, readout may include readout of a group of devices (such as a group of photosensitive regions of a pixel).

[0023] As used herein, the term "readout circuit" is a broad term and will be given its common and conventional meaning to those skilled in the art and is not limited to a specific or custom meaning. Specifically, the term may refer to, but is not limited to, an electronic unit configured to read out (i.e., to quantify and / or process) at least one physical characteristic and / or a change in at least one physical characteristic detected by a photodetector (or more specifically, by a photosensitive area). The readout electronic unit may include at least one of an operational amplifier, an analog-to-digital converter, a voltage divider, and a current shunt. The readout circuit may include at least one integrated circuit. The readout circuit may include at least one application-specific integrated circuit (ASIC) specifically configured to read out one or more pixels, more specifically, to read out multiple pixels. The readout circuit may be or may include at least one readout integrated circuit (ROIC). The readout circuit may be configured to process at least one detector current from a pixel, specifically a portion of the detector current, and obtain the signal value of the corresponding pixel.

[0024] As used herein, the term "abnormal pixel" is a broad term and will be given its common and conventional meaning to those skilled in the art and is not limited to a specific or custom meaning. The term may specifically refer to, but is not limited to, pixels exhibiting illogical signal behavior. Specifically, neighboring pixels of a photodetector may provide illogical signals, for example, due to unwanted electrical or optical connections, which may result in indistinguishable spectral trends or reproducible deviations from the sample response. For example, two or more pixels may be short-circuited. A pixel exhibiting illogical signal behavior may be referred to as an "abnormal pixel." An abnormal pixel may be or may include at least one of the following: a short-circuited pixel, a pixel with defective bonding lines, a pixel electrically connected to another pixel, or a crosstalk pixel. For example, an abnormal pixel may exhibit a systematic deviation in signal behavior from that of other pixels in the photodetector or from the signal behavior of one or more other regions of the photodetector, such as a deviation in signal behavior from that of other pixels in an array or matrix of pixels or from the signal behavior of one or more other regions of that array or matrix.

[0025] As used herein, the term "detection" is a broad term and will be given its common and conventional meaning to those skilled in the art and is not limited to a specific or custom meaning. The term may specifically refer to, but is not limited to, at least one process for determining the presence of anomalous pixels. Specifically, detecting anomalous pixels may include evaluating the signal behavior of each of a plurality of pixels. Quality control may include classifying pixels of a photodetector into reliable pixels and anomalous pixels. The results of detection may be stored in at least one log file. Detection may include masking all pixels classified as anomalous pixels among the plurality of pixels. Detection may be part of a quality control process. Detection may be performed on newly manufactured photodetectors. Alternatively or additionally, detection may also be performed on the photodetector during use, for example, to determine whether a pixel among a plurality of pixels degrades into an anomalous pixel during the use of the photodetector. Detection may include, for example, issuing at least one indication regarding the presence of anomalous pixels through at least one user interface.

[0026] As used herein, the term "automatic" is a broad term and will be given its common and conventional meaning to those skilled in the art, and is not limited to a specific or customized meaning. Specifically, the term may specifically refer to, but is not limited to, a process performed entirely by at least one computer and / or computer network and / or machine, particularly without manual action and / or user interaction. The method may be implemented at least partially by a computer. As used herein, the term "computer-implemented method" is a broad term and will be given its common and conventional meaning to those skilled in the art, and is not limited to a specific or customized meaning. The term may specifically refer to, but is not limited to, a method involving at least one computer and / or at least one computer network. The computer and / or computer network may include at least one processor configured to perform at least one method step in the method steps according to the invention. Specifically, each of these method steps is performed via a computer and / or computer network. The method may be performed completely automatically, specifically without user interaction.

[0027] The method steps can be executed in a given order. However, it should be noted that different orders are also possible. The method may include additional method steps not listed. Furthermore, one or more of the method steps may be executed once or repeatedly. Furthermore, two or more of the method steps may be executed simultaneously or in an overlapping manner.

[0028] The method includes the following steps:

[0029] a) Apply a skimming voltage V to each of the plurality of pixels. 撇除 And by using the readout circuit of the photodetector, the initial signal value S of each of the plurality of pixels is measured without illuminating the photodetector. 初始 ;

[0030] b) Change the discard voltage V of at least one pixel j among the plurality of pixels. 撇除,j And measure the actual signal value S of at least one other pixel k among the plurality of pixels. 实际,k Where k ≠ j;

[0031] c) By using at least one processor to compare the initial signal value of the additional pixel k with the actual signal value of the additional pixel k, wherein if the difference between the initial signal value and the actual signal value exceeds at least one predefined tolerance, the additional pixel k is detected as an abnormal pixel.

[0032] As used herein, the term "apply voltage" is a broad term and will be given its common and conventional meaning to those skilled in the art and is not limited to a specific or custom meaning. The term may specifically refer to, but is not limited to, the process of providing voltage to one or more elements or devices. Applying voltage to each of the plurality of pixels may include using at least one voltage generator, such as at least one voltage source and / or at least one voltage regulator. Voltage may be applied to the pixels in a controlled manner, such as by controlling the intensity, type, frequency, and / or temporal evolution of the applied voltage. Voltage may be applied to each pixel individually, such as by controlling the voltage applied to each pixel independently of other pixels.

[0033] As used herein, the term "purge voltage" is a broad term and will be given its common and conventional meaning to those skilled in the art and is not limited to a specific or custom meaning. Specifically, the term may refer to, but is not limited to, the voltage applied to each pixel for readout. Purge voltage can be a voltage applied to readout circuitry during pixel readout for charge removal. Specifically, as outlined above, a pixel is configured to generate a signal in response to optical radiation illuminating a corresponding photosensitive area of ​​the pixel. This signal may include at least one detector current, specifically one or more of a dark current signal and a photocurrent. As further outlined above, a pixel may include at least one purge circuitry configured to purge the detector current. A purge voltage may be applied to the purge circuitry. Specifically, a purge voltage may be applied to the purge circuitry to control at least one purge current passing through the purge circuitry. The detector current may be separated into a purge current passing through the purge circuitry and a residual current, which is processed by the readout circuitry to derive the signal value of the corresponding pixel. The signal value of the pixel may depend on the purge voltage applied to the purge circuitry of the corresponding pixel.

[0034] As used herein, the term "measurement" is a broad term and will be given its common and conventional meaning to those skilled in the art, and is not limited to a specific or customary meaning. Specifically, the term may refer to, but is not limited to, the quantitative determination of at least one representative value using at least one measurement signal. Specifically, measuring the signal value of a pixel among the plurality of pixels may include processing signals generated by the respective pixels and obtaining signal values ​​therefrom. As an example, the result of the measurement may include signal values ​​on a relative scale or a dimensionless scale. Therefore, signal values ​​can be measured in any unit.

[0035] As used herein, the term "initial signal value" is a broad term and will be given its common and conventional meaning to those skilled in the art and is not limited to a specific or custom meaning. The term may specifically refer to, but is not limited to, the signal value of a pixel under initial conditions. The initial signal value may be, or may include, the signal value of a pixel to which an initial rejection voltage is applied. Specifically, the rejection voltage applied to each pixel in step a) may define an initial rejection voltage. The initial signal value may be a signal value obtained by using a readout circuit while applying an initial rejection voltage to each pixel. The initial signal value may be used as a reference value. Specifically, variations and / or deviations in the signal values ​​of pixels can be identified by using the initial signal value, specifically by comparing it with the initial signal value. The initial signal value may be a single signal value and / or mean or average obtained by measuring the signal values ​​of a pixel multiple times while an initial rejection voltage is applied to the pixel.

[0036] As used herein, the term "no illumination" is a broad term and will be given its common and conventional meaning to those skilled in the art, and is not limited to any particular or custom meaning. Specifically, the term may refer to, but is not limited to, a situation where there is no optical radiation illuminating, specifically, no intentional illumination of the photosensitive area of ​​a pixel. Specifically, during the no-illumination phase, the light source illuminating the photosensitive area of ​​the pixel may be turned off. During the no-illumination phase, active illumination of the photosensitive area of ​​the pixel can be avoided. However, other light sources may be present, such as, specifically, ambient light.

[0037] As used herein, the term "changing voltage" is a broad term and will be given its common and conventional meaning to those skilled in the art, and is not limited to a specific or custom-defined meaning. Specifically, the term may refer to, but is not limited to, the process of changing the voltage applied to a component or device, specifically, to cause a measurable change in the output of the component or device. Changing the discard voltage of a pixel among a plurality of pixels may include changing the discard voltage applied to the pixel, specifically to the discard circuitry applied to the pixel. Changing the discard voltage can cause a change in the signal value of the pixel. For a functioning photodetector, changing the discard voltage of pixel j may not cause a change in the signal values ​​of other pixels, where k ≠ j.

[0038] Changing the skip voltage can include adjusting the skip voltage from at least one initial skip voltage. For example, changing the skip voltage can include increasing the skip voltage of pixel j from the at least one initial skip voltage. The skip voltage of the remaining pixels can be kept constant at the initial skip voltage. Alternatively or additionally, decreasing the skip voltage may also be feasible.

[0039] As used herein, the term "actual signal value" is a broad term and will be given its common and conventional meaning to those skilled in the art and is not limited to a specific or custom meaning. Specifically, the term may refer to, but is not limited to, the signal value of a pixel under modified conditions. The actual signal value can be or may include the signal value of an additional pixel k obtained during the application of at least one modified discard voltage to at least one pixel j, where k ≠ j. Specifically, the actual signal value may include at least one signal value obtained for an additional pixel k among a plurality of pixels while a modified discard voltage is applied to at least one pixel j different from that applied to the first pixel. During the measurement of the actual signal value, the discard voltage of the additional pixel k may remain constant. The actual signal value may be a single signal value and / or mean or average obtained by measuring the signal value of the additional pixel k multiple times while a modified discard voltage is applied to pixel j. Actual signal value S 实际,k Measurements can be taken without illuminating the photodetector, specifically without intentionally illuminating the photodetector.

[0040] Specifically, the actual signal value S can be measured for each additional pixel k among these pixels. 实际,k The actual signal values ​​of the multiple pixels can be measured using frame measurements covering all pixels. Frame measurements can specifically be coherent measurements performed on all pixels of the photodetector. Frame measurements can include temporally overlapping or parallel measurements of at least a portion of the multiple pixels, such as parallel measurements of columns or rows of pixels in the photodetector, or more specifically, parallel measurements of all pixels of the photodetector.

[0041] As used herein, the term "another pixel" is a broad term and will be given its common and conventional meaning to those skilled in the art and is not limited to a specific or custom meaning. The term may specifically refer to, but is not limited to, a pixel different from the pixel having the changed rejection voltage. The other pixel k may be different from pixel j. The other pixel may be specifically different from the pixel to which the changed rejection voltage is applied.

[0042] The other pixel k can be a pixel among these pixels, where k = j ± n, and n ∈ Specifically, the additional pixel k can be at least one of the nearest neighbor pixel of pixel j when k = j ± 1 and the second nearest neighbor pixel of pixel j when k = j ± 2.

[0043] As used herein, the term "comparison" is a broad term and will be given its common and conventional meaning to those skilled in the art and is not limited to a specific or custom meaning. Specifically, the term may refer to, but is not limited to, the process of evaluating at least one first information item relative to at least one second information item. Comparison may include evaluating an actual signal value relative to an initial signal value. Comparison may include directly comparing the initial signal value and the actual signal value, and / or indirectly comparing the initial signal value and the actual signal value (e.g., by utilizing further preprocessing of the corresponding signal values). Comparing the initial signal value and the actual signal value may include using the initial signal value and the actual signal value to determine at least one quotient. Alternatively or additionally, comparing the initial signal value and the actual signal value may include determining at least one difference between the initial signal value and the actual signal value. Comparison may specifically include determining the difference between the maximum value and the minimum value among the initial signal value and the actual signal value. This difference may be compared with a predefined tolerance to detect anomalous pixels.

[0044] Alternatively or additionally, comparing the initial signal value of another pixel k with the actual signal value of another pixel k may include at least one offset correction. Offset correction may be applied to both the initial signal value and the actual signal value. Offset correction may be applied before determining the difference between the initial signal value and the actual signal value. Alternatively or additionally, offset correction may be applied to the determined difference between the initial signal value and the actual signal value. Offset correction may take into account fluctuations in the signal value at the pixel due to noise.

[0045] The comparison can be performed automatically, specifically by using at least one processor. As used herein, the term "processor" is a broad term and will be given its common and conventional meaning to those skilled in the art, and is not limited to any particular or custom meaning. The term can specifically refer to, but is not limited to, any logic circuit configured to perform basic operations of a computer or system, and / or generally to a device configured to perform computations or logical operations. In particular, a processor can be configured to process the basic instructions that drive a computer or system. A processor can be or can include at least one of an integrated circuit (particularly an application-specific integrated circuit (ASIC)) or a data processing device, particularly a digital signal processor (DSP), a field-programmable gate array (FPGA), a microcontroller, a microcomputer, a computer, or an electronic communication unit (specifically a smartphone or tablet). As an example, a processor can include at least one arithmetic logic unit (ALU), at least one floating-point unit (FPU), such as a math coprocessor or a digital coprocessor, multiple registers, specifically configured to provide operands to the ALU and store the results of operations, and memories such as L1 and L2 cache memories. In particular, a processor can be a multi-core processor. Specifically, the processor may be or may include a central processing unit (CPU). Alternatively or alternatively, the processor may be or may include a microprocessor; therefore, the elements of the processor may be contained within a single integrated circuit (IC) chip. Alternatively or alternatively, the processor may be or may include one or more application-specific integrated circuits (ASICs) and / or one or more field-programmable gate arrays (FPGAs) and / or one or more tensor processing units (TPUs) and / or one or more chips, such as dedicated machine learning optimization chips. The processor may specifically be configured, for example, by software programming, to perform one or more detection operations. Additional components may be feasible, particularly at least one preprocessing device or data acquisition device. The processor may preferably be configured to execute at least one computer program, particularly at least one computer program that performs or supports the steps of the method according to the invention.

[0046] As used herein, the term "predefined tolerance" is a broad term and will be given its common and conventional meaning to those skilled in the art, and is not limited to a specific or custom meaning. Specifically, the term may refer to, but is not limited to, a quantitative measure used to assess the deviation between two values. Specifically, a predefined tolerance may be, or may include, a quantitative measure used to assess the deviation of an actual signal value from an initial signal value. The deviation of the actual signal value from the initial signal value can be compared to the predefined tolerance. If the deviation of the actual signal value from the initial signal value exceeds the predefined tolerance, the corresponding additional pixel k can be detected as an anomalous pixel. If the deviation of the actual signal value from the initial signal value is equal to or less than the predefined tolerance, the corresponding additional pixel k can be detected as a valid pixel. The predefined tolerance may include absolute quantitative measures, such as absolute thresholds (e.g., threshold counts), and / or relative quantitative measures, such as a tolerance level dependent on the initial signal value (e.g., a multiple of the initial signal value). The predefined tolerance can prevent bias in anomalous pixel detection, such as fluctuations in the signal value at the pixel due to noise. Predefined tolerances can be defined and / or determined before the automatic abnormal pixel detection method, and therefore can be referred to as “predefined”.

[0047] The method may further include selecting at least one pixel sequence comprising a number of pixels selected from the plurality of pixels. As used herein, the term "pixel sequence" is a broad term and will be given its common and conventional meaning to those skilled in the art and is not limited to a specific or custom meaning. The term may specifically refer to, but is not limited to, a set of pixels selected from the plurality of pixels. A pixel sequence may specifically comprise a set of non-neighboring pixels. A pixel sequence may comprise a regular pixel sequence, specifically a regular pixel sequence in which the number of pixels are spaced apart from each other by at least a predefined pixel interval. For example, the predefined pixel interval may be at least 5 pixels. Thus, in this example, the pixel sequence may comprise every sixth pixel of the plurality of pixels. However, any other pixel interval of 2 or more pixels may also be feasible. In step b), the discard voltage of each pixel in the pixel sequence may be changed simultaneously. The method may further include shifting the pixel sequence along the plurality of pixels. Specifically, the method may include shifting the pixel sequence along the plurality of pixels such that each pixel of the plurality of pixels is selected into the pixel sequence at least once. The pixel sequence may allow for the simultaneous testing of a large number of pixels. Furthermore, performing this method using the shifted pixel sequence ensures that there are no undetected anomalous pixel patterns. Additionally or alternatively, the pixel sequence allows for multiple measurements of the actual signal values ​​of other pixels, thus making the detection of anomalous pixels more reliable.

[0048] The method may further include repeating step b) for each pixel j of the plurality of pixels. Specifically, each pixel of the plurality of pixels may be selected at least once as pixel j having the changed skimming voltage. The method may include repeating step b) continuously for each pixel, or repeating step b) simultaneously for a certain number of pixels selected from the plurality of pixels.

[0049] In another aspect of the invention, a system for automatically detecting abnormal pixels in at least one photodetector is disclosed. As used herein, the term "system" is a broad term and will be given its common and conventional meaning to those skilled in the art and is not limited to a specific or custom meaning. Specifically, the term may refer to, but is not limited to, any set of interacting or interdependent components forming a whole. Specifically, these components may interact with each other to achieve at least one common function. At least two components may be processed independently, or may be coupled or connected.

[0050] The system includes at least one photodetector comprising a plurality of pixels j, wherein j is a pixel location and j ≥ 2. Each pixel includes at least one photosensitive region. Each pixel is configured to generate a signal in response to optical radiation illuminating a corresponding photosensitive region of the pixel. The photodetector further includes at least one readout circuit configured to read out the plurality of pixels. The system further includes at least one voltage generator for applying a skimming voltage V to each of the plurality of pixels. 撇除 The readout circuit is configured to measure the initial signal value S of each of the plurality of pixels without illuminating the photodetector. 初始 The voltage generator is further configured to change the skimming voltage V of one of the plurality of pixels, pixel j. 撇除,j The readout circuit is configured to measure the actual signal value S of at least one additional pixel k among the plurality of pixels. 实际,k Where k ≠ j. The system further includes at least one processor for comparing the initial signal value of the additional pixel k with the actual signal value of the additional pixel k. If the difference between the initial signal value and the actual signal value exceeds at least one predefined tolerance, the additional pixel k is detected as an anomalous pixel.

[0051] For definitions of terms and possible embodiments of the system or any part thereof, refer to the above description of the method for automatic abnormal pixel detection.

[0052] As used herein, the term "voltage generator" is a broad term and will be given its common and conventional meaning to those skilled in the art, and is not limited to any particular or custom meaning. The term may specifically refer to, but is not limited to, an electrical device configured to apply voltage. A voltage generator may be or may include at least one voltage source and / or at least one voltage regulator. A voltage generator may be specifically configured to apply a pick-off voltage to a plurality of pixels, specifically controlling the intensity, type, frequency, and / or temporal evolution of the voltage applied to each pixel individually in a controlled manner.

[0053] The photodetector can be specifically an infrared photodetector.

[0054] The photosensitive region may include at least one photoconductive material selected from the group consisting of: lead sulfide (PbS); lead selenide (PbSe); mercury cadmium telluride (HgCdTe); cadmium sulfide (CdS); cadmium selenide (CdSe); indium antimonide (InSb); indium arsenide (InAs); indium gallium arsenide (InGaAs); silicon (Si); silicon germanium (SiGe); lithium tantalate (LiTaO3); triglycine sulfate (TGS); platinum silicide (PtSi); quantum well infrared photodetector (QWIP); intrinsic semiconductor; organic semiconductor.

[0055] The system can be configured to perform the methods according to the present invention (such as any of the embodiments disclosed above and / or any other embodiments disclosed in further detail below).

[0056] In another aspect of the invention, a computer program is disclosed that includes instructions, when executed by a system according to the invention (such as any of the embodiments disclosed above and / or any other embodiments disclosed in further detail below), causing the system to perform the method according to the invention (such as any of the embodiments disclosed above and / or any other embodiments disclosed in further detail below).

[0057] In another aspect of the invention, a computer-readable storage medium is disclosed, specifically a non-transitory computer-readable storage medium comprising instructions that, when executed by a system according to the invention (e.g., according to any of the embodiments disclosed above and / or according to any other embodiments further detailed below), cause the system to perform the method according to the invention (e.g., according to any of the embodiments disclosed above and / or according to any other embodiments further detailed below).

[0058] As used herein, the term "computer-readable storage medium" can specifically refer to a non-transitory data storage device, such as a hardware storage medium on which computer-executable instructions are stored. Computer-readable storage media can specifically be or can include storage media such as random access memory (RAM) and / or read-only memory (ROM). Computer-readable storage media can specifically be or can include computer-readable data carriers.

[0059] This document further discloses and proposes a computer program comprising computer-executable instructions for performing the methods according to the invention in one or more embodiments included herein, when the program is executed on a computer or computer network. Specifically, the computer program may be stored on a computer-readable data carrier and / or a computer-readable storage medium.

[0060] Therefore, specifically, one, more, or even all of the method steps a) to c) indicated above can be performed by using a computer or computer network, preferably by using a computer program.

[0061] This document further discloses and proposes a computer program product having program code means for performing the method according to the invention in one or more embodiments included herein when the program is executed on a computer or computer network. Specifically, the program code means may be stored on a computer-readable data carrier and / or a computer-readable storage medium.

[0062] This document further discloses and proposes a data carrier having a data structure stored thereon, which, after being loaded into a computer or computer network (e.g., into the working memory or main memory of the computer or computer network), can perform methods according to one or more embodiments disclosed herein.

[0063] This document further discloses and proposes a computer program product having program code means stored on a machine-readable medium to perform methods according to one or more embodiments disclosed herein when the program is executed on a computer or computer network. As used herein, a computer program product refers to a program that is a tradable product. The product can generally exist in any format, such as in paper format, or on a computer-readable data carrier and / or computer-readable storage medium. Specifically, the computer program product can be distributed via a data network.

[0064] Furthermore, this document discloses and proposes a modulated data signal containing computer system or computer network readable instructions for performing methods according to one or more embodiments disclosed herein.

[0065] Referring to the computer implementation aspects of the present invention, one or more, or even all, of the method steps in one or more of the methods disclosed in the embodiments herein can be performed using a computer or computer network. Therefore, typically, any of the method steps involving the provision and / or manipulation of data can be performed using a computer or computer network. Generally, these method steps can include any method steps, except for those that typically require manual work, such as providing samples and / or performing certain aspects of actual measurements.

[0066] Specifically, this article further discloses:

[0067] - A computer or computer network including at least one processor, wherein the processor is adapted to perform a method according to one of the embodiments described in this specification.

[0068] - A computer-loadable data structure adapted to perform a method according to one of the embodiments described in this specification when the data structure is executed on a computer.

[0069] - A computer program, wherein the computer program is adapted, when executed on a computer, to perform a method according to one of the embodiments described in this specification.

[0070] A computer program comprising program means for performing a method according to one of the embodiments described herein when the computer program is executed on a computer or a computer network.

[0071] - A computer program comprising program means according to a preceding embodiment, wherein the program means is stored on a computer-readable storage medium.

[0072] - A storage medium wherein a data structure is stored on the storage medium, and wherein the data structure is adapted to perform a method according to one of the embodiments described herein after being loaded into the main storage device and / or working storage device of a computer or computer network.

[0073] - A computer program product having program code means, wherein the program code means may be stored or stored on a storage medium for performing a method according to one of the embodiments described herein when the program code means is executed on a computer or computer network.

[0074] The methods and apparatus according to the invention provide numerous advantages over known methods and apparatus. Specifically, the methods and systems for automatic abnormal pixel detection can reliably detect any abnormal pixels (e.g., electrically connected pixels) in a photodetector. The methods and systems for automatic abnormal pixel detection can be configured to inspect the photodetector using the pixel array itself and without using optical signals, specifically without using spectral measurements. By changing the rejection voltage, connections between pixels that are not visible in spectral measurements can be detected. Furthermore, the methods and systems for automatic abnormal pixel detection can allow inspection of the photodetector to locate short-circuited pixels, pixels with defective bonding lines, pixels electrically connected to another pixel, and / or crosstalk pixels (specifically in an array or matrix of multiple pixels).

[0075] Methods and systems for automatic abnormal pixel detection may specifically include adjusting individual pixels by varying the discarding current applied to each pixel. Additional remaining pixels can be measured and monitored. If any pixel other than the adjusted pixel is affected, that additional pixel can be detected as an abnormal pixel, which may have an electrical connection to the adjusted pixel. The method for automatic abnormal pixel detection can be part of quality control, such as part of a test function for testing the functionality of a photodetector. The discarding current of a pixel can be adjusted via a DAC value, and the signal value changes of other pixels can be measured and monitored. Specifically, adjustments can be made multiple times for each individual pixel among the plurality of pixels. For example, every sixth pixel can be adjusted. Frame measurements can then be performed. If any pixel other than the adjusted pixel exhibits a deviation from the frame DAC count, that additional pixel may have an electrical connection to the adjusted pixel, and thus an abnormal pixel is detected.

[0076] As used herein, the terms “have,” “include,” or “contain,” or any of their grammatical variations, are used in a non-exclusive manner. Thus, these terms can refer either to a situation where no other features exist in the entity described in the context besides those introduced by these terms, or to a situation where one or more other features exist. For example, the statements “A has B,” “A includes B,” and “A contains B” can refer either to a situation where no other elements exist in A besides B (i.e., A consists solely of B), or to a situation where entity A contains one or more other elements besides B (such as element C, elements C and D, or even other elements).

[0077] Furthermore, it should be noted that the terms "at least one," "one or more," or similar expressions indicating a feature or element may appear once or more, but are typically used only once when describing the corresponding feature or element. In most cases, the expressions "at least one" or "one or more" are not repeated when referring to the corresponding feature or element, but in fact, the corresponding feature or element may appear once or more.

[0078] Furthermore, as used herein, the terms “preferredly,” “more preferably,” “particularly,” “more particularly,” “specifically,” “more specifically,” or similar terms are used in combination with optional features without limiting the possibility of alternatives. Therefore, the features introduced by these terms are optional features and are not intended to limit the scope of the claims in any way. As those skilled in the art will recognize, the invention can be practiced by using alternative features. Similarly, features introduced by phrases such as “in embodiments of the invention” are intended to be optional features and do not limit any alternative embodiments of the invention, the scope of the invention, or the possibility of combining features introduced in this way with other optional or non-optional features of the invention.

[0079] In summary, and without excluding other possible embodiments, the following embodiments are conceivable:

[0080] Example 1: A method for automatically detecting abnormal pixels in at least one photodetector comprising a plurality of pixels, wherein each pixel includes at least one photosensitive region, wherein each pixel is configured to generate a signal in response to optical radiation illuminating a corresponding photosensitive region of the pixel, wherein the photodetector further includes at least one readout circuit configured to read out the plurality of pixels, wherein the method includes the following steps:

[0081] a) Apply a skimming voltage V to each of the plurality of pixels. 撇除 And by using the readout circuit of the photodetector, the initial signal value S of each of the plurality of pixels is measured without illuminating the photodetector. 初始 ;

[0082] b) Change the discard voltage V of at least one pixel j among the plurality of pixels. 撇除,j And measure the actual signal value S of at least one other pixel k among the plurality of pixels. 实际,k Where k ≠ j;

[0083] c) By using at least one processor to compare the initial signal value of the additional pixel k with the actual signal value of the additional pixel k, wherein if the difference between the initial signal value and the actual signal value exceeds at least one predefined tolerance, the additional pixel k is detected as an abnormal pixel.

[0084] Example 2: The method according to the previous example, wherein the abnormal pixel is at least one of a short-circuited pixel, a pixel with a defective bonding line, a pixel electrically connected to another pixel, or a crosstalk pixel.

[0085] Example 3: The method according to any one of the foregoing embodiments, wherein the additional pixel k is a pixel among the plurality of pixels, wherein k = j ± n, and n ∈ Specifically, it is at least one of the nearest neighbor pixel of pixel j when k = j ± 1 and the second nearest neighbor pixel of pixel j when k = j ± 2.

[0086] Example 4: The method according to any one of the foregoing embodiments, wherein the method further includes repeating step b) for each pixel j of the plurality of pixels.

[0087] Example 5: The method according to any one of the foregoing embodiments, wherein the actual signal value S is measured for each additional pixel k among the plurality of pixels. 实际,k .

[0088] Example 6: The method according to the previous example, wherein the actual signal value of the plurality of pixels is measured by frame measurement covering the plurality of pixels.

[0089] Example 7: The method according to any one of the foregoing embodiments, wherein the method further includes selecting at least one pixel sequence, the at least one pixel sequence comprising a certain number of pixels selected from the plurality of pixels, wherein, in step b), the skimming voltage is simultaneously changed for each pixel of the pixel sequence.

[0090] Example 8: The method according to the previous example, wherein the pixel sequence includes a regular pixel sequence, specifically a regular pixel sequence in which the aforementioned number of pixels are spaced apart from each other by at least a predefined pixel interval.

[0091] Example 9: The method according to any one of the preceding two examples, wherein the method further includes shifting the pixel sequence along the plurality of pixels.

[0092] Example 10: The method according to any one of the foregoing embodiments, wherein changing the skimming voltage includes adjusting the skimming voltage from at least one initial skimming voltage.

[0093] Example 11: The method according to any one of the foregoing embodiments, wherein the comparison includes determining the difference between the maximum value of the initial signal value and the actual signal value and the minimum value of the initial signal value and the actual signal value.

[0094] Example 12: The method according to any one of the foregoing embodiments, wherein comparing the initial signal value of the additional pixel k with the actual signal value of the additional pixel k includes at least one offset correction.

[0095] Example 13: The method according to any one of the foregoing embodiments, wherein the actual signal value S 实际,k The measurement was taken without illuminating the photodetector.

[0096] Example 14: The method according to any of the foregoing embodiments, wherein the method is at least partially implemented by a computer.

[0097] Example 15: A system for automatically detecting abnormal pixels in at least one photodetector, wherein the system includes the at least one photodetector, the at least one photodetector including a plurality of pixels j, wherein j is a pixel location and j ≥ 2, wherein each pixel includes at least one photosensitive region, wherein each pixel is configured to generate a signal in response to optical radiation illuminating a corresponding photosensitive region of the pixel, wherein the photodetector further includes at least one readout circuit configured to read out the plurality of pixels, wherein the system further includes at least one voltage generator for applying a rejection voltage V to each of the plurality of pixels. 撇除 The readout circuit is configured to measure the initial signal value S of each of the plurality of pixels without illuminating the photodetector. 初始 The voltage generator is further configured to change the rejection voltage V of one of the plurality of pixels j. 撇除,j The readout circuit is configured to measure the actual signal value S of at least one additional pixel k among the plurality of pixels. 实际,k Where k ≠ j, the system further includes at least one processor for comparing the initial signal value of the additional pixel k with the actual signal value of the additional pixel k, wherein if the difference between the initial signal value and the actual signal value exceeds at least one predefined tolerance, the additional pixel k is detected as an abnormal pixel.

[0098] Example 16: The system according to the previous example, wherein the photodetector is an infrared photodetector.

[0099] Example 17: A system according to any one of the foregoing embodiments relating to the system, wherein the photosensitive region comprises at least one photoconductive material selected from the group consisting of: lead sulfide (PbS); lead selenide (PbSe); mercury cadmium telluride (HgCdTe); cadmium sulfide (CdS); cadmium selenide (CdSe); indium antimonide (InSb); indium arsenide (InAs); indium gallium arsenide (InGaAs); silicon (Si); silicon germanium (SiGe); lithium tantalate (LiTaO3); triglycine sulfate (TGS); platinum silicide (PtSi); quantum well infrared photodetector (QWIP); intrinsic semiconductor; organic semiconductor.

[0100] Example 18: A system according to any one of the foregoing embodiments relating to a system, wherein the system is configured to perform a method according to any one of the foregoing claims relating to a method.

[0101] Example 19: A computer program including instructions that, when executed by a system according to any one of the foregoing embodiments relating to a system, cause the system to perform a method according to any one of the foregoing embodiments relating to a method.

[0102] Example 20: A computer-readable storage medium, specifically a non-transitory computer-readable storage medium, includes instructions that, when executed by a system according to any one of the foregoing embodiments relating to a system, cause the system to perform a method according to any one of the foregoing embodiments relating to a method. Attached Figure Description

[0103] Further optional features and embodiments will be disclosed in more detail, preferably in conjunction with the dependent claims, in the following embodiments. As those skilled in the art will recognize, the corresponding optional features can be implemented independently and in any feasible combination. The scope of the invention is not limited to the preferred embodiments. Embodiments are schematically depicted in the accompanying drawings. The same reference numerals in these drawings denote the same or functionally equivalent elements.

[0104] In the attached diagram:

[0105] Figure 1 A graph showing spectral measurements using a photodetector is presented;

[0106] Figure 2 An embodiment of a system for automatic abnormal pixel detection is illustrated in schematic diagram;

[0107] Figure 3 A flowchart illustrating an embodiment of a method for automatic abnormal pixel detection is shown;

[0108] Figure 4A graph showing frame measurements with the modified skip voltage applied to every sixth pixel is presented.

[0109] Figure 5 A graph showing the results of a method for automatic abnormal pixel detection; and

[0110] Figure 6 A graph showing the actual signal values ​​and spectral measurements is presented. Detailed Implementation

[0111] Figure 1 A graph showing spectral measurements using a photodetector with multiple pixels is presented. Specifically, the graph shows the relative amplitude 110 of the signal value for each pixel, expressed in relative units, as the pixel position 112 varies. Figure 1 The figure shows the dynamic spectrum measured for the photodetector. For example... Figure 1 As shown by reference numeral 114 in the attached figure, the spectrum reveals illogical signal behavior in certain pixels. Pixels exhibiting illogical signal behavior can be classified as anomalous pixels 116.

[0112] exist Figure 2 The diagram illustrates an exemplary embodiment of a system 118 for automatic abnormal pixel detection. System 118 includes at least one photodetector 120 comprising a plurality of pixels j (denoted by reference numeral 122), where j is a pixel location 112 and j ≥ 2. Each pixel 122 includes at least one photosensitive region 124. Each pixel 122 is configured to generate a signal in response to optical radiation illuminating a corresponding photosensitive region 124 of the pixel. The photodetector 120 may specifically be an infrared photodetector. As an example, the photosensitive region 124 may include at least one photoconductive material selected from the group consisting of: lead sulfide (PbS); lead selenide (PbSe); mercury cadmium telluride (HgCdTe); cadmium sulfide (CdS); cadmium selenide (CdSe); indium antimonide (InSb); indium arsenide (InAs); indium gallium arsenide (InGaAs); silicon (Si); silicon germanium (SiGe); lithium tantalate (LiTaO3); triglycine sulfate (TGS); platinum silicide (PtSi); quantum well infrared photodetector (QWIP); intrinsic semiconductor; organic semiconductor.

[0113] The photodetector 120, including the plurality of pixels 122, is in Figure 2 The diagram schematically illustrates a number of pixels 122. As an example, the photodetector 120 may include a plurality of pixels 112 arranged in a linear array. The linear pixel array 122 may include, for example, 256 pixels 122. However, other numbers and / or arrangements of pixels 122 are also possible.

[0114] The photodetector 120 further includes at least one readout circuit 126 configured to read out the plurality of pixels 122. Figure 2 As shown, the readout circuit 126 may be at least partially integrated into the photodetector 120. For example, the readout circuit 126 may include at least one application-specific integrated circuit (ASIC), specifically configured to read out one or more pixels 122, more specifically, to read out the plurality of pixels 122. The readout circuit 126 may be or may include at least one readout integrated circuit (ROIC).

[0115] like Figure 2 As shown, system 118 further includes at least one voltage generator 128, which is used to apply a skimming voltage V to each of the plurality of pixels 122. 撇除 As an example, voltage generator 128 may be or may include at least one voltage source and / or at least one voltage regulator.

[0116] Furthermore, the readout circuit 126 is configured to measure the initial signal value S of each of the plurality of pixels 122 without illuminating the photodetector 120. 初始 The voltage generator 128 is further configured to change the rejection voltage V of one of the plurality of pixels 122 (indicated by reference numeral 130). 撇除,j The readout circuit 126 is configured to measure the actual signal value S of at least one additional pixel k (represented by reference numeral 132) among the plurality of pixels 122. 实际,k , where k ≠ j.

[0117] System 118 further includes at least one processor 134 for comparing the initial signal value of another pixel k 132 with the actual signal value of another pixel k 132. If the difference between the initial signal value and the actual signal value exceeds at least one predefined tolerance, the other pixel k 132 is detected as an anomalous pixel 116.

[0118] System 118 can be configured to perform operations according to the present invention (e.g., according to...). Figure 3 The method described in the exemplary embodiments thereof and / or according to any other embodiments disclosed herein. Therefore, for a description of the method, refer to Figure 3 The description.

[0119] Figure 3 A flowchart illustrating an exemplary embodiment of a method for automatically detecting abnormal pixels using at least one photodetector 120 comprising a plurality of pixels 122 is shown. The photodetector 120 can be configured according to... Figure 2The photodetector 120 shown is implemented in an exemplary embodiment. Therefore, for a detailed description of the photodetector 120, please refer to... Figure 2 The description.

[0120] The method steps can be executed in a given order. However, it should be noted that different orders are also possible. The method may include additional method steps not listed. Furthermore, one or more of the method steps may be executed once or repeatedly. Furthermore, two or more of the method steps may be executed simultaneously or in an overlapping manner.

[0121] The method includes the following steps:

[0122] a) (indicated by reference numeral 136) Apply a rejection voltage V to each of the plurality of pixels 122. 撇除 And by using the readout circuit 126 of the photodetector 120, the initial signal value S of each of the plurality of pixels 122 is measured without illuminating the photodetector 120. 初始 ;

[0123] b) (Indicated by reference numeral 138) Change the discard voltage V of at least one pixel j 130 among the plurality of pixels 122. 撇除,j And measure the actual signal value S of at least one additional pixel k 132 among the plurality of pixels 122. 实际,k Where k ≠ j;

[0124] c) (represented by reference numeral 140) by using at least one processor 134 to compare the initial signal value of another pixel k 132 with the actual signal value of another pixel k 132, wherein if the difference between the initial signal value and the actual signal value exceeds at least one predefined tolerance, the other pixel k 132 is detected as an anomalous pixel 116.

[0125] The method may further include selecting at least one pixel sequence comprising a number of pixels selected from a plurality of pixels 122. The pixel sequence may include a regular pixel sequence, specifically a regular pixel sequence in which the number of pixels are spaced apart from each other by at least a predefined pixel interval. For example, the predefined pixel interval may be at least 5 pixels. Therefore, in this example, the pixel sequence may include every sixth pixel 122 of the plurality of pixels 122. However, any other pixel interval may also be feasible.

[0126] In step b), the discard voltage of each pixel 122 in the pixel sequence can be changed simultaneously. This is in Figure 4 As shown in the image. Figure 4A graph showing frame measurements across multiple pixels 122 is presented. Specifically, Figure 4 The measured signal value 142 for each pixel 122, varying with pixel position 112, is shown. For example... Figure 4 As shown, the rejection voltage of every sixth pixel 122 is changed, and thus the signal value 142 of the pixel 122 to which the changed rejection voltage is applied is enhanced.

[0127] The method may further include shifting the pixel sequence along the plurality of pixels 122. Specifically, the method may include shifting the pixel sequence along the plurality of pixels 122 such that each of the plurality of pixels 122 is selected into the pixel sequence at least once. The pixel sequence may allow for the simultaneous testing of a large number of pixels 122. Furthermore, performing the method on the shifted pixel sequence can ensure that there is no pattern of undetected anomalous pixels. Additionally or alternatively, the pixel sequence may allow for multiple measurements of the actual signal values ​​of other pixels, and thus can make the detection of anomalous pixels more reliable.

[0128] Figure 5 A graph showing exemplary results of a method for automatic abnormal pixel detection is provided. Specifically, Figure 5 The diagram shows the measured actual signal values ​​144 of additional pixels k 132, varying with pixel position 112, for each pixel 122. By changing the rejection voltage of pixel j 130, some of the additional pixels k 132 exhibit increased actual signal values ​​compared to their initial signal values. Figure 5 In the example, the initial signal value is approximately 10,000 counts. (As in...) Figure 5 As can be seen, the photodetector 120 under test has two short-circuited pixel pairs and three short-circuited pixel pairs, whose actual signal values ​​exceed a predefined threshold by more than the initial signal value. These pixels can be detected as anomalous pixels 116. Figure 5 In the example, aberrant pixels 116 have different resistances due to short circuits, causing their corresponding actual signal values ​​to differ from the measured signal count. However, even short-circuited pixels with higher resistance can be detected using methods for automatic aberrant pixel detection.

[0129] Figure 6 A graph showing the actual signal values ​​and spectral measurements is presented. Specifically, Figure 6 Two dynamic spectral measurements (indicated by reference numeral 146) for a photodetector 120 with anomalous pixel 116 are shown. For the spectral measurements, in Figure 6 On the left y-axis of the graph, the relative amplitude 110 of the signal value 112 for each pixel 122, varying with pixel position 112, is shown in relative units. Further, Figure 6Exemplary results (denoted by reference numeral 148) of a method for automatic anomalous pixel detection performed on the same photodetector 120 used to obtain spectral measurements 146 are shown. These results are in Figure 6 As shown on the right y-axis, the actual signal value 144 measured for another pixel k 132 varies with pixel position 112. (As in...) Figure 6 As can be seen, pixels 122 of the photodetector 120 that exhibit unreasonable signal behavior 114 in spectral measurements can also be detected as anomalous pixels 116 by executing the method for automatic anomalous pixel detection according to the present invention. Furthermore, by using the method for automatic anomalous pixel detection according to the present invention, pixels 122 (indicated by reference numeral 150) that exhibit only minor signal unreasonableness in spectral measurements can also be detected as anomalous pixels 116.

[0130] List of reference signs

[0131] .

Claims

1. A method for automatically detecting abnormal pixels in at least one photodetector (120) comprising a plurality of pixels (122), wherein, Each pixel (122) includes at least one photosensitive region (124), wherein each pixel (122) is configured to generate a signal in response to optical radiation illuminating the corresponding photosensitive region (124) of the pixel, wherein the photodetector (120) further includes at least one readout circuit (126) configured to read out the plurality of pixels (122), wherein the method includes the following steps: a) Apply a rejection voltage V to each of the plurality of pixels (122). 撇除 And by using the readout circuit (126) of the photodetector (120), the initial signal value S of each of the plurality of pixels (122) is measured without illuminating the photodetector (120). 初始 ; b) Change the rejection voltage V of at least one pixel j (130) among the plurality of pixels (122). 撇除,j And measure the actual signal value S of at least one additional pixel k (132) among the plurality of pixels (122). 实际,k , where k ≠ j, and the additional pixel k (132) is at least one of the nearest neighbor pixel of pixel j (130) in the case of k = j ± 1 and the second nearest neighbor pixel of pixel j (130) in the case of k = j ± 2; c) By using at least one processor (134), the initial signal value of the additional pixel k (132) is compared with the actual signal value of the additional pixel k (132), wherein if the difference between the initial signal value and the actual signal value exceeds at least one predefined tolerance, the additional pixel k (132) is detected as an anomalous pixel (116).

2. The method according to the preceding claim, wherein, An abnormal pixel (116) is at least one of a short-circuited pixel, a pixel with a defective bonding line, or a crosstalk pixel.

3. The method according to any one of the preceding claims, wherein, The method further includes repeating step b for each pixel j (130) of the plurality of pixels (122).

4. The method according to any one of the preceding claims, wherein, The actual signal value S is measured for each additional pixel k (132) of the plurality of pixels (122). 实际,k The actual signal values ​​of the plurality of pixels (122) are measured by frame measurement covering the plurality of pixels (112).

5. The method according to any one of the preceding claims, wherein, The method further includes selecting at least one pixel sequence, the at least one pixel sequence comprising a number of pixels selected from the plurality of pixels (122), wherein, in step b), the skimming voltage is simultaneously changed for each pixel (122) of the pixel sequence.

6. The method according to the preceding claim, wherein, The pixel sequence includes a regular pixel sequence, specifically a regular pixel sequence in which the number of pixels are spaced apart from each other by at least a predefined pixel interval.

7. The method according to any one of the preceding two claims, wherein, The method further includes shifting the pixel sequence along the plurality of pixels (122).

8. The method according to any one of the preceding claims, wherein, Changing the skimming voltage includes adjusting the skimming voltage from at least one initial skimming voltage.

9. The method according to any one of the preceding claims, wherein, The comparison includes determining the difference between the maximum value of the initial signal value and the actual signal value, or the minimum value of the initial signal value and the actual signal value.

10. The method according to any one of the preceding claims, wherein, Comparing the initial signal value of the additional pixel k (132) with the actual signal value of the additional pixel k (132) includes at least one offset correction.

11. A system (118) for automatically detecting abnormal pixels in at least one photodetector (120), wherein, The system (118) includes at least one photodetector (120), which includes a plurality of pixels j (122), wherein j is a pixel location and j ≥ 2, wherein each pixel (122) includes at least one photosensitive region (124), wherein each pixel (122) is configured to generate a signal in response to optical radiation illuminating the corresponding photosensitive region (124) of the pixel, wherein the photodetector (120) further includes at least one readout circuit (126), which is configured to read out the plurality of pixels (122), wherein the system (118) further includes at least one voltage generator (128), which is used to apply a rejection voltage V to each of the plurality of pixels (122). 撇除 The readout circuit (126) is configured to measure the initial signal value S of each of the plurality of pixels (122) without illuminating the photodetector (120). 初始 The voltage generator (128) is further configured to change the rejection voltage V of one of the plurality of pixels (122) pixel j (130). 撇除,j The readout circuit (126) is configured to measure the actual signal value S of at least one additional pixel k (132) among the plurality of pixels (122). 实际,k , where k ≠ j, and the system (118) further includes at least one processor (134) for comparing the initial signal value of the additional pixel k (132) with the actual signal value of the additional pixel k (132), wherein if the difference between the initial signal value and the actual signal value exceeds at least one predefined tolerance, the additional pixel k (132) is detected as an anomalous pixel (116).

12. The system (118) according to the preceding claim, wherein, The system (118) is configured to perform the method according to any one of the foregoing claims relating to the method.

13. A computer program comprising instructions which, when executed by a system (118) according to any one of the preceding claims relating to a system (118), cause the system (118) to perform a method according to any one of the preceding claims relating to a method.

14. A computer-readable storage medium comprising instructions that, when executed by a system (118) according to any one of the preceding claims relating to a system (118), cause the system (118) to perform a method according to any one of the preceding claims relating to a method.

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