Optoelectronic detection device, corresponding lidar and detection method

Abstract

The present invention provides a photoelectric detection device, comprising: a detection unit, which can receive incident single photons and convert them into electrical signals; a filter unit, which is arranged upstream of the optical path of the detection unit to filter the photons incident on the detection unit; and a processing unit, which is configured to determine the number of actually incident photons according to the electrical signals and the transmittance of the filter unit. Through the embodiments of the present invention, the dynamic range of the receiving end of the lidar is improved, and the performance of the lidar is improved.

Description

Technical Field

[0001] The present disclosure generally relates to the field of optoelectronic technologies, and particularly to an optoelectronic detection device, a corresponding lidar, and a detection method. Background Art

[0002] Single-photon detection technology has advantages such as ultra-high sensitivity and ultra-fast response speed, and can detect the smallest energy particles of light. It is currently an important detection method. The energy of a single photon is extremely small. To detect a single photon, special optoelectronic devices must be used. A single-photon avalanche diode is a specific avalanche photodiode (APD) with a working voltage higher than the breakdown voltage. An avalanche photodiode operating in Geiger mode is also called a single-photon avalanche diode (SPAD). SPAD has become the best device choice for single-photon detection due to its high avalanche gain, fast response speed, low power consumption, etc. SPAD amplifies the photocurrent based on the physical mechanisms of impact ionization and avalanche multiplication, thereby improving the detection sensitivity. In Geiger mode, the working voltage of SPAD is greater than its avalanche breakdown voltage, which can ensure that even the carriers excited by the incidence of a single photon can cause an avalanche effect. The excited carriers drift into the depletion layer. Under the action of the strong electric field in SPAD, the carriers are instantaneously accelerated and obtain sufficient energy, continuously collide with the lattice, and the newly generated carriers continue to impact the lattice under the action of the electric field, generating new carriers. Such a chain reaction causes the number of carriers to increase avalanche-like, and the reverse current rises to the milliampere level within nanoseconds or even sub-nanoseconds. However, avalanche is a self-sustaining behavior, and SPAD itself cannot spontaneously quench it. To protect SPAD from being damaged by large currents, SPAD must be used in conjunction with a quenching circuit. After an avalanche occurs, the bias voltage of SPAD must be quickly reduced below the breakdown voltage to quench the avalanche, and then quickly pulled back above the breakdown voltage to restore SPAD to the state of waiting to detect photons. Therefore, for each detected single photon, SPAD will multiply and output a natural discrete electrical pulse signal, and then the useful signal buried in the noise can be identified and extracted by using the peripheral circuit to realize signal discrimination and counting.

[0003] Currently, SPAD units in lidar ranging applications can be divided into two categories: active quenching and passive quenching. The passive quenching SPAD unit is as Figure 8A shown. When a photon arrives, Figure 8A the diode 1 biased in Geiger mode in Figure 8B triggers an avalanche, generating the avalanche current aec in Figure 8BMedium waveform p2), and then the avalanche is quenched. Node 2 is discharged back to the ground potential by the quenching resistor R, and the diode 1 returns to the Geiger bias region. The waveform of node 2 becomes a digital pulse p3 (node 3) with a certain driving ability after passing through the buffer and is output to the subsequent processing circuit. The buffer is usually composed of multiple inverters with a fixed switching threshold. It can be seen from this process that the SPAD has a dead time. The actively quenched SPAD unit is as Figure 9A shown. When a photon arrives, the diode 1 biased in the Geiger mode triggers an avalanche, generating Figure 9B the avalanche current aec in Figure 9B . At this time, the NMOS transistor connecting the anode of the diode and the ground is turned off (because the voltage of the gate G of the NMOS is 0V), and the NMOS is in a high-impedance state. The avalanche current generates a voltage at the drain of the NMOS transistor, and then the avalanche is quenched. Node 2 maintains a high level ( DELAY the waveform p2 in Figure 9B ) until after a time delay T DELAY (typically from a few nanoseconds to dozens of nanoseconds), the high level propagates to the gate G ( Figure 9B the waveform pG in

[0004] ), causing the NMOS to conduct, and node 2 is discharged to 0V, and the diode returns to the Geiger bias region. The pulse width of node 2 is approximately equal to the duration of TDELAY, and the waveform of node 2 becomes a digital pulse p3 (node 3) with a certain driving ability after passing through the buffer and is output to the subsequent processing circuit. The dotted part in the waveform p3 represents the dead time of the SPAD. During the time period corresponding to the dotted line, since the NMOS transistor continuously conducts and pulls node 2 to the ground potential, the circuit is not in the normal working state of waiting for photons to arrive. This period of time is regarded as the dead time until the NMOS transistor returns to the cut-off state and the circuit returns to the working state.

[0004] Whether it is active quenching or passive quenching, the SPAD unit has a period of time during which the circuit is not working properly and cannot measure photons. The period during which the SPAD cannot detect photons is called the dead time. Based on the inherent characteristics of SPADs devices, the dead time is inevitable. Due to the existence of the dead time, the dynamic range of the detection device using SPAD technology is limited by the number of SPAD detectors actually used. Among them, the dynamic range is a physical quantity used to describe the ability of SPADs devices to receive photons. For example, assume that a SPADs detection unit consists of a SPADs array composed of 10x10 SPAD detectors. Then, the detection unit can receive at most 100 photons at a time. That is, the dynamic range of the detection unit is 1-100. If the number of echoes received at one time exceeds 100 photons, such as 200 or more photons, since 100 detectors in the detection unit have entered the dead time, the remaining extra photons cannot be measured. If you want to accurately measure the light intensity of the obtained echo, currently, you can only expand the number of SPAD detectors used in the detection unit. For example, expand it to a 20*10 array to achieve the measurement of 200 photons in one echo, etc.

[0005] For a photodetector using a silicon photomultiplier (abbreviated as SiPM), usually, this kind of photodetector is realized by using multiple SiPM units (or can be called a pixel). Each SiPM unit uses multiple parallel-connected SPADs (refer to Figure 10A and Figure 10B , Figure 10A which shows a current circuit implementation method of a SiPM; Figure 10B which shows another current circuit implementation method of a SiPM with fast output). And according to the total amount of photons received by the array at one time, the superposition current outputs a pulse. Although it will not be affected by the dead time of individual SPADs in the array during measurement, obviously, the upper limit of the dynamic range of this photodetector is also limited by the number of SPADs used in the SiPM unit itself.

[0006] Obviously, in this way, if you want to construct a detection unit with a large enough dynamic range, more SPAD detectors are needed, the device cost increases, and at the same time, due to the increase in the number of devices, its corresponding power consumption will also increase greatly. When the light intensity of the signal light to be measured is extremely large, the corresponding cost and power consumption of the detection unit required will become very large. The content in the background technology section is only the technology known to the inventor and does not necessarily represent the prior art in this field. Summary of the Invention

[0007] The present invention provides a lidar receiver with a large dynamic range, which solves the problem of small dynamic range of the receiver during single-photon detection.

[0008] In view of at least one defect of the prior art, the present invention provides an optoelectronic detection device, comprising:

[0009] A detection unit, which can receive single photons of incident light and convert them into electrical signals;

[0010] A filter unit, which is arranged upstream of the optical path of the detection unit to filter photons of the light beam incident on the detection unit;

[0011] A processing unit, which is configured to determine the actual light intensity of the incident light according to the electrical signal and the transmittance of the filter unit.

[0012] According to one aspect of the present invention, the detection unit includes a plurality of detection units, and the filter unit includes a plurality of filter units with different transmittances; and at least two of the plurality of detection units respectively correspond to filter units with different transmittances.

[0013] According to one aspect of the present invention, the plurality of detection units of the detection unit respectively correspond to a plurality of levels from low to high according to the peak transmittance of the corresponding filter unit. Among them, when the continuous saturation times of the detection unit with a higher level exceed a predetermined threshold, the detection information of the detection unit with a lower level is used for measurement.

[0014] According to one aspect of the present invention, the detection unit is implemented by any one of the following:

[0015] - SiPM unit;

[0016] - SPADs array.

[0017] According to one aspect of the present invention, each of the detection units includes a plurality of detectors, the detectors are single-photon avalanche diodes, and each of the detectors can be individually addressed. Among them, at least one of the plurality of detection units includes a plurality of detectors that can correspond to a plurality of filter units with different transmittances.

[0018] According to one aspect of the present invention, each detection unit includes multiple groups of detectors, and filter units with different transmittances are respectively arranged upstream of the optical paths of each group.

[0019] According to one aspect of the present invention, the filter unit is implemented by a narrowband filter.

[0020] The present invention also provides a lidar, comprising:

[0021] A transmitting unit configured to transmit a detection laser beam for detecting a target object;

[0022] A receiving unit, the receiving unit including the photoelectric detection device as described above, the photoelectric detection device being configured to receive the echo after the detection laser beam is reflected by the target object.

[0023] The present invention also provides a detection method for a lidar, the lidar being as described above, wherein the method includes the following steps:

[0024] Transmit a detection light beam;

[0025] The filter portion of the photoelectric detection device filters the echo corresponding to the detection light beam;

[0026] The detection portion of the photoelectric detection device receives the filtered echo and converts it into an electrical signal;

[0027] The processing unit of the photoelectric detection device determines the actual light intensity of the echo according to the obtained electrical signal and the transmittance of the corresponding filter portion.

[0028] By providing one or more filter units with different transmittances for the detection portion in the lidar in the embodiments of the present invention, the limitation of the dynamic range of the detection portion itself is broken through. Without changing the dynamic range of the devices used in the detection portion, that is, without increasing costs and power consumption, the overall dynamic range of the receiving end of the lidar is expanded; thereby improving the overall performance of the lidar. Description of the Drawings

[0029] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0030] Figure 1 Shows a schematic diagram of a photoelectric detection device according to an embodiment of the present invention;

[0031] Figure 2 Shows a schematic diagram of a photoelectric detection device according to another embodiment of the present invention;

[0032] Figure 3 Shows a schematic diagram of a photoelectric detection device according to another embodiment of the present invention;

[0033] Figure 4 Shows a block diagram of a lidar according to an embodiment of the present invention; and

[0034] Figure 5 Shows a flowchart of a lidar detection method according to an embodiment of the present invention;

[0035] Figure 6 Illustrates a distribution pattern of multiple detection units of a photoelectric detection device according to an embodiment of the present invention;

[0036] Figure 7 Illustrates another distribution pattern of multiple detection units of a photoelectric detection device according to an embodiment of the present invention;

[0037] Figure 8A Illustrates a schematic diagram of a current passive quenching SPAD detector circuit; Figure 8B Illustrates the Figure 8B Pulse diagram of the corresponding circuit;

[0038] Figure 9A Illustrates a schematic diagram of a current active quenching SPAD detector circuit; Figure 9B Illustrates the Figure 9A Pulse diagram of the corresponding circuit;

[0039] Figure 10A Illustrates a current circuit implementation of a SiPM; Figure 10B Illustrates another current circuit implementation of a SiPM. Detailed implementation manners

[0040] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the drawings and the description are considered to be exemplary in nature rather than restrictive.

[0041] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0042] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection: it can be a mechanical connection, an electrical connection, or a connection that allows mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, and can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being "above", "over", and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "below", "beneath", and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0044] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0045] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0046] Figure 1 A block diagram of a photoelectric detection device 100 according to an embodiment of the present invention is shown. The following will be combined with Figure 1 to describe the photoelectric detection device 100 in detail.

[0047] As Figure 1As shown in the figure, the photoelectric detection device 100 includes a detection unit 10, a filter unit 20, and a processing unit 30. The detection unit 10 can receive incident single photons and convert them into electrical signals. The filter unit 20 is arranged upstream of the optical path of the detection unit 10 to filter the photons (the light beam L1 in the figure) incident on the detection unit 10. The filter unit 20 has a certain transmittance, so a part of the photons can be filtered out, and the remaining photons (the light beam L2 in the figure) are incident on the detection unit 10 and converted into electrical signals by the detection unit 10. The processing unit 30 is coupled to the detection unit 10 and receives the electrical signal, and is configured to determine the actual light intensity of the incident light according to the electrical signal and the peak transmittance of the filter unit 20.

[0048] Among them, each detector can be implemented by a photodetector with single-photon detection ability. The detection unit 10 can include a plurality of addressable detection units. Preferably, the detection unit according to the present invention can be implemented by an SPADs array or a SiPM unit.

[0049] Among them, the SPADs array is composed of a plurality of individually addressable SPAD devices; the SiPM unit is formed by a plurality of parallel-connected SPAD devices. For the SPADs array, each SPAD device can be detected and addressed individually. Therefore, by detecting the output of each SPAD device in the SPADs array, the number of photons received by the SPADs array can be judged. Combining the peak transmittance of the filter unit 20, the actual number of incident photons can be determined, and then the light intensity can be determined. For the SiPM detection unit, the light intensity can be determined based on the peak value of the output pulse of each detection unit and the transmittance of the filter unit 20, which will be described in detail below.

[0050] Those skilled in the art should understand that the single-photon avalanche diode described here is only an example, and other types of photodetectors with single-photon detection ability and the arrays composed of them should also be included in the scope of the present invention.

[0051] Among them, according to an embodiment of the present invention, the filter unit can be implemented by a filter, or a device such as an attenuation sheet. Preferably, a narrowband filter corresponding to the bandwidth of the pulsed signal light of the lidar can be used. More preferably, the filter unit described in the present invention can be implemented by a variety of narrowband filters with different peak transmittances.

[0052] Those skilled in the art can understand that the existing filter production process, such as the ion-assisted deposition (IAD) process, can be used to produce the filters required in the present invention by directly bombarding the film to be coated with an ion source during deposition.

[0053] Since the peak transmittance of a filter may be affected by factors such as the optical thickness of the filter, different filters with different peak transmittances can be obtained by adjusting the optical thickness of the filter; alternatively, by directly adjusting factors that affect the optical thickness, such as refractive index and physical thickness, filters with different peak transmittances can be obtained.

[0054] According to a specific embodiment of the present invention, it is assumed that the detection unit 10 includes a 10x10 SPAD array, and the dynamic range of the detection unit 10 itself is 0-100; the transmittance of the filter unit 20 is 50%, that is, for the photons reaching the filter unit 20, 50% of the photons can be transmitted through the filter unit 20, and the remaining 50% are filtered out by the filter unit 20. The echo reaching the photoelectric detection device 100 passes through the filter unit 20 and then reaches the detection unit 10. If the detection unit 10 outputs an electrical signal of 100 photons, the processing unit 30 determines, based on the electrical signal corresponding to these 100 photons and in combination with the transmittance of 50% of the filter unit 20, that the actual number of photons reaching the photoelectric detection device 100 currently is 200.

[0055] That is to say, the dynamic range of the photoelectric detection device 100 can be extended to 0-200, which is twice the dynamic range of the detection unit 10 itself used.

[0056] Similarly, an SiPM array can also be used as the detection unit of the detection part. When an SiPM array is used as the detection unit, a filter can be provided upstream of the optical path of each SiPM. The transmittance of the filter is known. Based on the peak value of the output pulse of the SiPM and in combination with the transmittance of the corresponding filter, the light intensity of the incident light can be determined. Therefore, after using the combination of SiPM and filter, by combining the filter and the peak value of the output pulse, the true pulse intensity can be obtained.

[0057] Since the SiPM array uses multiple parallel-connected SPADs and outputs corresponding pulses according to the total amount of photons received by the array. Since the number of SPAD devices in the SiPM array is relatively large, generally it will not be affected by the dead time of individual SPADs in the array during measurement. However, obviously, the upper limit of the dynamic range of the SiPM array is also limited by the number of SPADs inside the array.

[0058] Those skilled in the art can easily understand that due to the easy saturation characteristic of the SPAD detector, when the filter unit 20 is not used, regardless of whether the actual incident echo is 100 photons or 200 photons, the detection unit 10 can only output an electrical signal of 100 photons. That is to say, the processing unit 30 will not be able to determine whether the actual echo light intensity is 100 photons or 200 photons.

[0059] However, after adopting the filter unit 20 such as the present solution, the light intensity of the echo is weakened to the range that the detection unit 10 can detect. Moreover, since the transmittance of the filter unit is known, the actual light intensity of the echo can be inversely deduced based on the detected number of photons and the transmittance of the filter unit. Furthermore, the effect of measuring the echo with a stronger light intensity is achieved based on the existing detection unit. Those skilled in the art can understand that the number of SPAD detectors included in the detection unit described in this specification is only an example for clear illustration, and in practice, a detection unit may include more or fewer detectors.

[0060] According to a preferred embodiment of the present invention, for the photoelectric detection device 100 described above, the detection part 10 can be composed of a plurality of detection units, which jointly constitute the detection surface of the detection part 10. Correspondingly, the filter unit 20 includes a plurality of filter subunits, which respectively correspond to the plurality of detection units. Among them, the transmittance of the plurality of filter subunits can be any one of the following:

[0061] 1) The transmittance of each of the plurality of filter subunits is the same, or,

[0062] 2) The transmittance of some of the plurality of filter subunits is different;

[0063] For example, the transmittance of the filter subunit arranged upstream of the optical path of a part of the detection units is 50%, while the transmittance of the filter subunit arranged upstream of the optical path of the remaining detection units is 20%, etc.

[0064] 3) The transmittance of each of the plurality of filter subunits is different.

[0065] Correspondingly, the output of each detection unit according to this embodiment can be read separately, so that the processing unit 30 can calculate the number of photons incident on the area of the detection unit according to the electrical signal output by each detection unit and the transmittance of the filter subunit corresponding to the detection unit, and accumulate the number of photons of the plurality of detection units to calculate the total number of actually incident photons.

[0066] According to the first preferred embodiment of the present invention, refer to Figure 2 . Figure 2Shown in it is a photoelectric detection device 100A according to a preferred embodiment of the present invention, which also includes a detection part 10, a filter part 20, and a processing unit 30 (not shown). Among them, the detection part 10 is composed of a planar array of 8x8 detectors, and each detector can respond to incident single photons. The detection part 10 includes 4 detection units, namely 10-1, 10-2, 10-3, and 10-4 respectively. Each detection unit includes 16 detectors. Each detection unit corresponds to a field of view range. Corresponding to the multiple detection units, the filter part 20 also includes four filter units, namely 20-1, 20-2, 20-3, and 20-4 respectively, which are respectively arranged upstream of the optical paths of the detection units 10-1, 10-2, 10-3, and 10-4, as Figure 2 shown by the dotted square boxes in it. The transmittances of the four filter units are, for example, different from each other, being 70%, 90%, 30%, and 50% respectively. In this way, the dynamic range of the photoelectric detection device can be greatly expanded.

[0067] According to another preferred embodiment of the present invention, each of the detection units in the photoelectric detection device is composed of a linear array or a planar array of detectors, and each of the detectors can be individually addressed. According to an embodiment of the present invention, among the multiple detectors included in the same detection unit, the peak transmittances of the corresponding filter units can also be different.

[0068] Preferably, among the multiple detection units, there is at least one detection unit, and the multiple detectors in the at least one detection unit can correspond to multiple filter units with different transmittances. For example, each detector can be set to correspond to one filter unit, and the transmittances of the multiple filter units respectively corresponding to the multiple detectors are different; or for another example, the multiple detectors are respectively grouped into multiple detector groups, each of the detector groups corresponds to one filter unit, and the transmittances of the respective filter units respectively corresponding to the multiple detector groups are different.

[0069] Optionally, Figure 2The detection units 10-1, 10-2, 10-3, and 10-4 therein can all be implemented by respective SiPM arrays. Taking the detection unit 10-1 as an example, it can be implemented by a SiPM array including 16 parallel-connected SPADs, and the other detection units are also implemented in the same way, which will not be elaborated here. Correspondingly, the filter units 20-1, 20-2, 20-3, and 20-4 corresponding to the respective detection units 10-1, 10-2, 10-3, and 10-4 can have different transmittances, which are 70%, 90%, 30%, and 50% respectively as described above. Then, the processing unit 30 reads the output pulses of each detection unit 10-1, 10-2, 10-3, and 10-4 respectively, and based on the peak values of the output pulses of each detection unit and the transmittance of the corresponding filter unit, the pulse intensity of the incident light can be determined.

[0070] According to an embodiment of the present invention, multiple detectors in at least one detection unit can correspond to multiple filter units with different transmittances. The following will be described in detail with reference to Figure 3 .

[0071] According to the second preferred embodiment of the present invention, with reference to Figure 3 .

[0072] Figure 3 FIG. shows a schematic diagram of a photoelectric detection device 100B according to an embodiment of the present invention, which also includes a detection section 10, a filter section 20, and a processing unit 30 (not shown). As Figure 3 shown, the detection section 10 is composed of an 8x8 SPADs array, and this SPADs array includes 4 detection units, namely 10-1', 10-2', 10-3', and 10-4' respectively. Each detection unit includes four groups of detectors, and each group of detectors includes 4 SPADs (such as the 2*2 area marked with 1, 2, 3, and 4 respectively in Figure 3 ). That is, each of the detection units 10-1', 10-2', 10-3', and 10-4' has 16 SPADs, and each detection unit can correspond to a field of view range.

[0073] Among them, taking the detection unit 10-1' as an example, the detectors therein can correspond to multiple filter units with different transmittances. As Figure 3 shown, the detection unit 10-1' corresponds to four filter units, namely 20-11, 20-12, 20-13, and 20-14, which are respectively arranged upstream of the optical paths of the four groups of detectors 1, 2, 3, and 4 of the detection unit 10-1'. The transmittances of the four filter units 20-11, 20-12, 20-13, and 20-14 are 20%, 90%, 5%, and 50% in sequence respectively.

[0074] By adopting filter units with various peak transmittances, while expanding the active range of the detection unit, it is also possible to maintain higher precision.

[0075] Continuing with the description of the aforementioned second embodiment, the detection unit 10-1' including 16 SPAD detectors, the number of photons m detected by it is m = [50%*n / 4] + [20%*n / 4] + [90%*n / 4] + [5%*n / 4]; where m is the actual number of photons detected by the detection unit 10-1', and n is the actual number of photons incident on this detection unit 10-1'. After obtaining the photon count output by the detection unit 10-1', based on the corresponding rounding function, a possible value or set of values of a relatively accurate incident photon number n can be obtained.

[0076] Those skilled in the art can understand that Figure 3 only the filter unit corresponding to the detection unit 10-1' is schematically shown in [the figure]. The transmittances of the filter units corresponding to the remaining detection units 10-2', 10-3', 10-4' can be the same or different, and these are all within the protection scope of the present invention.

[0077] According to the solution of this embodiment, by addressing each detector inside the detection unit (i.e., each pixel), the number of photons obtained in different regions within the pixel is respectively acquired, and then the number of photons corresponding to the entire pixel is obtained, thereby improving the detection accuracy of each detection unit.

[0078] According to the above principle, by setting different filter films for each group of detectors or detection units, an echo detection part with a larger dynamic range and better accuracy can be obtained.

[0079] Through the present invention, echo detection with a large dynamic range can be achieved using a smaller number of detectors. Compared with the prior art, to achieve detection with the same dynamic range, the required device cost is lower and the power consumption is smaller.

[0080] The present invention also relates to a lidar, such as Figure 4 the block diagram of a lidar 400 according to an embodiment of the present invention shown in [the figure]. The lidar 400 includes a transmitting unit 410 and a receiving unit 420, wherein the transmitting unit 410 is configured to emit a detection laser beam L1 for detecting a target object OB, and the receiving unit 420 includes the photoelectric detection device 100 and is configured to receive the echo L1' of the detection laser beam reflected on the target object OB and output an echo signal.

[0081] According to a preferred embodiment of the present invention, a plurality of detection units of the detection part correspond to multiple levels according to the peak transmittance of their corresponding filter units from high to low. Among them, when the continuous saturation times of the detection units corresponding to the levels with higher peak transmittance exceed a predetermined threshold, the detection information of the detection units with lower levels is used for detection.

[0082] Combined Figure 6 and Figure 7 。 Figure 6 Figure 9 shows a distribution mode of a plurality of detection units of a photoelectric detection device according to an embodiment of the present invention. Specifically, Figure 6 Figure 10 shows a distribution structure of 10*10 detection units. Among them, the detection units in the 5*5 area of the shaded part correspond to the filter with a peak transmittance of 10%, and the remaining areas correspond to the filter with a peak transmittance of 90%. Obviously, the dynamic range of the shaded area is larger than that of the remaining areas.

[0083] As a preferred solution, Figure 7 Figure 11 shows another distribution mode of a plurality of detection units of a photoelectric detection device according to an embodiment of the present invention. Among them, Figure 7 Among the 10*10 detection units shown, 25 detection units correspond to the filter with a peak transmittance of 10% (i.e., the shaded part), and the remaining detection units correspond to the filter with a peak transmittance of 90%; and, the 25 detection units corresponding to the filter with a peak transmittance of 10% are evenly distributed throughout the array, and each detection unit with a 10% filter is surrounded by the detection units with a 90% filter.

[0084] During detection, first measure according to the detection information of the detection units in the area with a 90% transmittance filter; when it is found that within a predetermined detection time, the saturation times of the detection units in this area exceed the predetermined threshold, then measure according to the detection information of the detection units in the area with a 10% transmittance filter. By using filters with different peak transmittances, the dynamic range of the detection part can be expanded, and the detection of a larger range of light intensities can be realized.

[0085] It can be understood that for the detection part adopting the Figure 7 shown distribution mode, while having a large dynamic range, the consistency of the detection part will be better. No matter which area the light spot actually falls into, detection data under two dynamic ranges can be obtained for selection. And it will not produce the situation that when the light spot does not fall into the 5*5 local shaded area in the Figure 6 distribution structure, the detection information with a 10% dynamic range cannot be obtained.

[0086] Moreover, those skilled in the art should understand that each detection unit can be separately read out through a corresponding readout circuit. And by grouping the detection units with the same dynamic range into one group, the detection information of the detection units with different dynamic ranges can be obtained respectively. Then, according to the above strategy, the detection information of the detection unit with the required dynamic range can be selected to complete the measurement process.

[0087] According to another preferred embodiment of the present invention, the detection part includes a plurality of detection units, and these plurality of detection units belong to three levels, from high to low in turn: the first-level detection unit, the peak transmittance of the corresponding filter unit is 90%; the second-level detection unit, the peak transmittance of the corresponding filter unit is 40%; the third-level detection unit, the peak transmittance of the corresponding filter unit is 40%.

[0088] When the detection part is turned on, first detect based on the detection information of the first-level detection unit with the highest transmittance (i.e., the smaller dynamic range). When the continuous saturation times of the first-level detection unit exceed the first threshold within a predetermined length of time (or within a continuous number of frames), use the detection information of the second-level detection unit with a lower transmittance filter (i.e., its corresponding larger dynamic range) to detect; similarly, when the continuous saturation times of the second-level detection unit exceed the second threshold, use the detection information of the third-level detection unit to detect.

[0089] Among them, the thresholds of each level can be the same or different, and can be determined based on the actual situation and requirements. Preferably, the thresholds corresponding to each level can correspond to the number of emission pulses of the emission end of the lidar.

[0090] For example, the threshold of each level can be a predetermined number M. When M pulse signals received within a predetermined period of time cause the detection unit of the current dynamic range to be saturated each time, that is, each emitted pulse signal will cause the detection unit of the current dynamic range to be saturated, then at this time, use the detection information of the detection unit with a higher dynamic range, that is, a lower peak transmittance, to perform the measurement.

[0091] In this way, according to the saturation degree of the detection unit, different detection units corresponding to different transmittances are read out step by step in stages. On the one hand, the overall dynamic range of the detection part can be improved, and on the other hand, good detection accuracy can be ensured at the same time. In addition, those skilled in the art can easily understand that the above description is only exemplary, and the transmittances of the filter units corresponding to different detection units can be divided into two levels, three levels, or even four levels, five levels, etc. more levels according to needs.

[0092] Figure 5 Shows a flowchart of a lidar detection method according to an embodiment of the present invention. The lidar detection method 500 uses Figure 4The lidar 400 shown in the figure detects a target object OB at a certain distance from the lidar 400. The following will be combined with Figure 5 The lidar detection method 500 will be described in detail. As shown in the figure, the detection method 500 includes the following steps:

[0093] In step S501: Emit a detection beam. The emission unit 410 of the lidar 400 emits a detection laser beam into the surrounding environment where the target object is located to detect the target object.

[0094] In step S502: The filter part of the photoelectric detection device filters the echo corresponding to the detection beam.

[0095] After the detection laser beam emitted in step S501 encounters the target object OB, diffuse reflection occurs, and a part of the reflected echo is received by the receiving unit 420 of the lidar 400.

[0096] Among them, the receiving unit 420 includes the photoelectric detection device according to the present invention.

[0097] A filter part 20 is provided upstream of the optical path of the detection part 10 of the photoelectric detection device. The filter part 20 includes a plurality of filter units with the same or different transmittances. The echo first enters the plurality of filter units, and the filter unit with a certain transmittance filters the echo photons, and a part of the photons of the echo pass through the filter unit.

[0098] In step S503: The detection part of the photoelectric detection device receives the filtered echo and converts it into an electrical signal. The detection part 10 includes a plurality of detection units. One or more of the detection units correspond to a plurality of the filter units. The filtered echo photons are received by the detection units and the optical signal is converted into an electrical signal.

[0099] Among them, the detection unit is composed of a linear array or a planar array of single-photon detection devices. The single-photon detection device is, for example, a single-photon avalanche diode SPAD, and other photodetectors with single-photon detection capabilities can also be selected.

[0100] In step S504: The processing unit of the photoelectric detection device determines the number of actually incident photons according to the obtained electrical signal and the transmittance of the corresponding filter part. The processing unit 30 is respectively coupled to the detection part 10 and the filter part 20, and calculates the number of actually detected photons according to the electrical signal transmitted from the detection part 10 and the transmittance of the filter units in the filter part 20.

[0101] The present invention proposes a structure and method for improving the dynamic range of the receiving end of a lidar, and a lidar having such a structure, by providing a filter unit with a certain transmittance. Compared with the traditional receiving end having a SPAD array, the embodiment of the present invention saves the power consumption of the device, improves the dynamic range of the receiving end of the lidar, and further improves the detection accuracy of the lidar.

[0102] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An optoelectronic detection device, comprising: A detection unit, which can receive single photons of incident light and convert them into electrical signals; A filter unit, which is arranged upstream of the optical path of the detection unit to filter photons of the light beam incident on the detection unit; A processing unit, which is configured to determine the actual light intensity of the incident light according to the electrical signal and the transmittance of the filter unit; Wherein, the detection unit includes a plurality of detection units, and the filter unit includes a plurality of filter units with different transmittances; and at least two of the plurality of detection units respectively correspond to filter units with different transmittances; The plurality of detection units of the detection unit respectively correspond to multiple levels from low to high according to the peak transmittance of the corresponding filter unit. Among them, when the continuous saturation times of the detection unit with a higher level exceed a predetermined threshold, the detection information of the detection unit with a lower level is used for measurement.

2. The optoelectronic detection device according to claim 1, wherein, The detection unit is implemented by any one of the following: - SiPM unit; - SPADs array.

3. The optoelectronic detection device according to claim 1, wherein, Each of the detection units respectively includes a plurality of detectors. Among them, the detector is a single-photon avalanche diode, and each of the detectors can be individually addressed. Among the plurality of detection units, there is at least one detection unit, and the plurality of detectors in the at least one detection unit can correspond to a plurality of filter units with different transmittances.

4. The optoelectronic detection device according to claim 1, wherein, Each detection unit includes multiple groups of detectors, and filter units with different transmittances are respectively arranged upstream of the optical path of each group.

5. The optoelectronic detection device according to claim 1, wherein the filter unit is implemented by a narrowband filter.

6. A lidar, comprising: A transmitting unit, which is configured to emit a detection laser beam for detecting a target; A receiving unit, which includes the optoelectronic detection device according to any one of claims 1-5, and the optoelectronic detection device is configured to receive the echo after the detection laser beam is reflected by the target.

7. A detection method for a lidar, the lidar being as described in claim 6, wherein, The method includes the following steps: Emitting a detection light beam; The filter unit of the optoelectronic detection device filters the echo corresponding to the detection light beam; The detection unit of the optoelectronic detection device receives the filtered echo and converts it into an electrical signal; The processing unit of the optoelectronic detection device determines the actual light intensity of the echo according to the obtained electrical signal and the transmittance of the corresponding filter unit.

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