TWI795903B - Photonics systems and methods - Google Patents

Abstract

Systems and methods for imaging in the short wave infrared (SWIR), photodetectors with low dark current and associated circuits for reducing dark currents and methods for generating image information based on data of a photodetector array. A SWIR imaging system may include a pulsed illumination source operative to emit radiation pulses in the SWIR band towards a target resulting in reflected radiation from the target; (b) an imaging receiver including a plurality of Ge PDs operative to detect the reflected SWIR radiation and a controller, operative to control activation of the receiver for an integration time during which the accumulated dark current noise does not exceed the time independent readout noise.

Description

Photonic systems and methods

This application relates to and claims priority to U.S. Provisional Patent Application Numbers: 63/075,426, filed September 8, 2020, 63/093,945, filed October 20, 2020, and 63/094,913, filed October 22, 2020, All of these are hereby incorporated by reference in their entirety.

The invention relates to photonic systems, methods and computer program products. More specifically, the present invention relates to electro-optic devices and lasers used in infrared (IR) photonics.

Photodetection devices such as photodetector arrays (also referred to as "photosensor arrays") comprise a plurality of photosites, each comprising one or more photodiodes and a capacitor, the one or more photodiodes are used to detect impinging light, and the capacitor is used to store the charge provided by the photodiode. The capacitance can be implemented as a dedicated capacitor and/or using parasitic capacitance of the photodiode, transistor and/or other components of the PS. Hereafter, in this specification and for the sake of simplicity, the term "photodetecting device" is often replaced by the abbreviation "PDD" and the term "photodetector array" is often replaced by the abbreviation The word "PDA", while the term "photodiode" is often replaced by the acronym "PD".

The term "photosite" refers to a single sensor element (also known as a "sensor", as in the words "sensor" and "sensor") in an array of sensors. cell (cell)" or "sensor (sensor)" and "element (element)" combination), and is also known as "sensor element (sensor element)", "photosensor element (photosensor) element)", "photodetector element (photodetector element)", etc. In the following, "photosite" is generally replaced by the abbreviation "PS". Each PS may comprise: one or more PDs (eg, if a color filter array is implemented, multiple PDs detecting light of different parts of the spectrum may alternatively be collectively referred to as a single PS). Besides the PD, the PS may also include: some circuits or additional components.

Dark current is a well-known phenomenon when referring to many PDs, it is the current flowing through the PD even though no photons enter the device. Dark current in many PDs may be caused by the random generation of electrons and holes in a depleted region of the PD.

In some cases, there is a need to provide optical sites with photodiodes characterized by a relatively high dark current, while implementing capacitors of limited size. In some cases, it is desirable to provide PSs with PDs characterized by a relatively high dark current while reducing the dark current's effect on an output detection signal. In many PSs characterized by high dark current accumulation, there is a need and it would be beneficial to overcome the detrimental effects of dark current on many electro-optic systems. Hereafter and for the sake of simplicity, the term "electrooptical" may be replaced by the abbreviation "EO".

Shortwave infrared (SWIR) imaging enables a range of applications that are difficult to perform using visible light imaging. Applications include electronic board inspection, solar cell inspection, product inspection, gated imaging, identification and classification, surveillance, anti-counterfeiting, process quality control and more. Many existing indium gallium arsenide (InGaAs) based SWIR imaging systems are expensive to manufacture and are currently subject to limited manufacturing capabilities.

Therefore, it would be beneficial to be able to provide a SWIR imaging system using a more cost-effective number of photoreceivers based on a number of PDs that are more easily integrated into the surrounding electronics.

According to an aspect of the present invention, a SWIR optical system is disclosed, the SWIR system includes a passive Q-switched laser (also referred to herein as a "P-QS laser"), the passive Q-switched laser includes : a gain medium comprising a gain medium crystalline (GMC) material which is ceramic neodymium-doped yttrium aluminum garnet (Nd:YAG); a saturable absorber (SA) rigidly attached to the gain medium, the SA comprising a ceramic SA crystalline material selected from the group of doped ceramic materials consisting of: V³⁺:YAG and cobalt-doped crystalline materials; and a The optical cavity, the gain medium and the SA are located in the optical cavity, the optical cavity includes a high reflectivity mirror and an output coupler.

Hereafter in this description and for the sake of simplicity, the term "saturated absorber" is frequently replaced by the abbreviation "SA".

According to an aspect of the present invention, a kind of SWIR optical system is disclosed, and this SWIR system comprises a P-QS laser, and this P-QS laser comprises: A gain medium, comprises a GMC material, and this GMC material is ceramic Nd: YAG; a SA rigidly attached to the gain medium, the SA comprising a ceramic SA crystalline material selected from the group of doped ceramic materials consisting of: V³⁺:YAG and a plurality of divalent cobalt-doped crystalline materials; and an optical cavity, the gain medium and the SA are located in the optical cavity, the optical cavity includes a high reflectivity mirror and an output coupler.

According to an aspect of the present invention, a SWIR optical system is disclosed, the SWIR system includes a P-QS laser, the P-QS laser includes: a gain medium, the gain medium includes a ceramic GMC material, the ceramic GMC The material is a ceramic neodymium-doped rare earth element crystal; an SA, rigidly attached to the gain medium, the SA comprising a ceramic SA crystalline material selected from the group consisting of a plurality of doped crystalline materials consisting of A group: V³⁺:YAG and various cobalt-doped crystalline materials; and an optical cavity in which the gain medium and the SA are located, the optical cavity includes a high reflectivity mirror and an output coupler.

According to an aspect of the present invention, a method for manufacturing a plurality of parts of a P-QS laser is disclosed, the method comprising: packing at least one first powder into a first mold; Compacting the at least one first powder to produce a first green body; filling at least one second powder different from the at least one first powder into a second mold; compacting the at least one powder in the second mold a second powder to produce a second green body; heating the first green body to produce a first crystalline material; heating the second green body to produce a second crystalline material; the second crystalline material connected to the first crystalline material. In such a case, one of the first crystalline material and the second crystalline material is a neodymium-doped crystalline material and is a gain medium for the P-QS laser, and wherein the first The other of a crystalline material and a second crystalline material is an SA for the P-QS laser and is selected from a group of crystalline materials consisting of: a neodymium-doped crystalline material and a doped crystalline material selected from the group of doped crystalline materials consisting of V³⁺:YAG and cobalt-doped crystalline materials. Also, in such a case, at least one of the gain medium and the SA is a ceramic crystalline material.

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

In the set forth figures and description, the same reference numerals designate those components common to different embodiments or configurations.

Unless specifically stated otherwise, as will be apparent from the following discussion, it is understood that throughout the discussion of the specification, terms such as "processing", "calculating", "computing", Terms such as "determining", "generating", "setting", "configuring", "selecting", "defining", etc. include the manipulation of data and/or An action and/or process of a computer transformed into other data expressed as physical quantities, such as electronic quantities, and/or data representing the physical objects.

The terms "computer", "processor" and "controller" should be construed broadly to cover any kind of electronic device having data processing capabilities, including by way of non-limiting examples: a person Computer, a server, a computing system, a communication device, a processor (such as a digital signal processor (DSP), a microcontroller, a field programmable logic gate array (FPGA), a special function integrated circuit circuits, etc.), any other electronic computing device, or any combination thereof.

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

As used herein, the phrases "for example", "such as", "for instance" and their conjugations describe various non-limiting examples of the presently disclosed subject matter . References in the specification to "one case", "some cases", "other cases" or variations thereof mean that a particular feature is described in connection with the embodiment, A structure or characteristic is included in at least one embodiment of the presently disclosed subject matter. Thus, appearances of the phrase "one case," "some cases," "other cases," or variations thereof do not necessarily mean the same embodiment(s) .

It is to be appreciated that certain features of the presently disclosed subject matter, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of presently disclosed subject matter that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

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

Any reference to a method in the specification shall be applied mutatis mutandis to a system capable of performing the method, and shall be mutatis mutandis to a non-transitory computer-readable medium storing instructions which, once executed by a computer Execute causes the method to be executed.

Any reference in the specification to a system should be mutated to a method executable by the system, and should be mutated to a non-transitory computer-readable medium storing instructions executable by the system.

Any reference in this specification to a non-transitory computer-readable medium or similar terms shall be applied mutatis mutandis to being capable of executing the instructions stored on the non-transitory computer-readable medium, and shall be In a method of execution, the computer reads the plurality of instructions stored in the non-transitory computer readable medium.

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

Implementation of the methods and systems of the present invention involves performing or completing certain selected tasks or steps manually, automatically, or a combination thereof. Moreover, according to the actual instrumentation and equipment of the preferred embodiments of the method and system of the present invention, several selected steps may be implemented by hardware or by software on any operating system of any firmware or a combination thereof. For example: as hardware, selected steps of the invention may be implemented as a chip or as a circuit. As software, selected steps of the invention could be implemented as software instructions being executed by a computer using any suitable operating system. In any case, selected steps of the methods and systems of the present invention may be described as being performed by a data processor, such as a computing platform for executing instructions.

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

As used herein, an "active" imaging system is operable to detect light reaching the system from its field of view (FOV), which is detected by an imaging receiver comprising a plurality of PDs, and The plurality of detection signals are processed to provide one or more images of the field of view or a portion thereof. The term "image" means a digital representation of a scene detected by the imaging system, which stores a color value for each element (pixel) in the image, each pixel color representing Different parts of the field (eg, a 0.02° by 0.02° portion of the FOV, depending on receiver optics) light reaches the imaging system. It is to be noted that, optionally, the imaging system can also be operated to generate other representations of objects or lights in the FOV (e.g. a depth map, 3D model, polygon mesh), but the term "image ” means a two-dimensional (2D) image without depth data.

The system 100 includes an illumination source (IS) 102 operable to emit a plurality of pulses of radiation in the SWIR band toward one or more targets 104, causing reflected radiation from the object to appear within the range of the system 100. direction is reflected back. In FIG. 1A , outgoing illumination is indicated at 106 , and illumination reflected toward system 100 is indicated at 108 . Portions of the emitted radiation may also be reflected in other directions, deflected or absorbed by the target. The term "target" means any object in the FOV of the imaging sensor, such as solid, liquid, flexible and rigid objects. Some non-limiting examples of such objects include vehicles, roads, people, animals, plants, buildings, electronic devices, clouds, microscopic samples, items in manufacture, and the like. Any suitable type of illumination source 102 may be used, such as one or more lasers, one or more light emitting diodes (LEDs), one or more incident flashlights, any combination of the above, or the like. As discussed in more detail below, illumination source 102 may optionally include one or more active lasers, or one or more P-QS lasers.

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

The term "germanium PD (Ge PD)" refers to where within the germanium, within a germanium alloy (eg SiGe) or at the interface between germanium (or germanium alloy) and another material (eg silicon, SiGe) Any PD in which light-induced electronic excitation (later detectable as photocurrent) occurs. Specifically, the term "germanium PD" refers to both pure germanium PDs and applies to germanium-silicon PDs. When germanium PDs containing germanium and silicon are used, different concentrations of geranium can be used. For example, the relative portion of germanium in a germanium PD (whether alloyed with or adjacent to silicon) may be in the range of 5% and 99%. For example: the relative fraction of germanium in a plurality of germanium PDs may be between 15% and 40%. It is to be noted that materials other than silicon may also be part of the germanium PD, such as aluminum, nickel, silicide or any other suitable material. In some implementations of the invention, the plurality of germanium PDs can be pure germanium PDs (comprising greater than 99.0% germanium).

It is to be noted that the receiver could be implemented as a PDA fabricated on a single wafer. Any such PD array discussed throughout this disclosure may be used as receiver 110 . The germanium PDs may be arranged in any suitable arrangement, such as a rectangular matrix (straight rows and columns of germanium PDs), honeycomb tiling, and even irregular configurations. Preferably, the number of germanium PDs in the receiver allows high resolution imagery to be produced. For example: the number of PDs can be on the order of 1 megapixel, 10 megapixels or more.

In some embodiments, receiver 110 has the following specifications: a. HFOV (horizontal field of view) [m]: 60 b. WD (working distance) [m]: 150 c. Pixel size [um]: 10 d. Resolution (on target) [mm]: 58 e. Pixel # [H]: 1,050 f. Pixel#[V]: 1112 g. Aspect ratio: 3:1 h. Viewing angle [rad]: 0.4 i. Target reflectivity [%]: 10% j. Collection (ratio of collected photons to emitted photons assuming 100% target reflectivity and assumed Lambertian reflectivity): 3e-9.

In addition to impinging SWIR light as described above, the electrical signal generated by each of the plurality of germanium PDs also represents: a. Readout noise is random, and its magnitude has nothing to do with integration time (or substantially nothing to do). An example of such noise includes Nyquist Johnson noise (also known as thermal noise or kTC noise). In addition to statistical components, the readout process may also introduce a DC component into the signal, but the term "readout noise" relates to the random component of the signal introduced by the readout process. b. Dark current noise, which is random and accumulates during the integration time (ie, it depends on the integration time). In addition to the statistical component, dark current also introduces a DC component (which may or may not be canceled, such as discussed in relation to Figures 12A to 22) to the signal, but the term "dark current noise "dark current noise" belongs to the random component of the signal that is accumulated by dark current during the integration time.

Some germanium PDs, especially some PDs that combine germanium with another material such as silicon for example, are characterized by a relatively high level of dark current. For example, the dark current of multiple germanium PDs may be greater than 50 μA/cm² (related to a surface area of the PD), or even greater (eg greater than 100 μA/cm², greater than 200 μA/cm² or greater than 500 μA/cm²). Depending on the surface area of the PD, such multiple levels of dark current can be translated to 50 picoamperes (pA) per Ge PD or higher (e.g. over 100 pA per Ge PD, over 200 pA per Ge PD, over 500 pA per Ge PD , or more than 2nA per germanium PD). It is to be noted that multiple PDs of different sizes may be used, such as about 10 mm², about 50 mm², about 100 mm², about 500 mm². It should be noted that when the plurality of germanium PDs are subjected to different levels of nonzero bias (nonzero bias), the plurality of germanium PDs may generate dark currents of different magnitudes (this is the case in each of the plurality of germanium PDs). cause a dark current of, for example, greater than 50 pA).

System 100 also includes a controller 112 that controls the operation of receiver 110 (and optionally also illumination source (IS) 102 and/or other components) and image processor 114 . Therefore, the controller 112 is configured to control the activation of the receiver 110 within a relatively short integration time, thereby limiting the effect of the accumulation of dark current noise on the signal quality. For example, the controller 112 may be operable to control the activation of the receiver 110 for an integration time during which the accumulated dark current noise does not exceed the read noise of the irrelevant integration time.

。(替代地，將y軸視為在一匹配的非線性多項式比例上被繪製)。同樣，在零積分時間(在這樣的一情況下，累積的暗電流雜訊為零)時，該多個軸不會彼此交叉。Reference is now made to FIG. 2, which is an exemplary graph illustrating the relative magnitude of noise power after various durations of integration times in accordance with examples of the inventive subject matter. For a given laser pulse energy, the signal-to-noise ratio (SNR) is mainly determined by the noise level, which includes the dark current noise (noise of the dark photocurrent) and thermal noise (also referred to as called kTC noise). As shown in the exemplary graph of FIG. 2, depending on the integration time of the germanium-based receiver 110, either the dark current noise or the thermal noise dominates the SNR affecting the electrical signal of the PD. Since the controller 112 limits the activation time of the germanium photodetector for a relatively short time (within the range designated as "A" in FIG. 2), there is not much electron emission from dark current noise. is collected, so the SNR is improved and is therefore mainly affected by thermal noise. For a longer receiver integration time, the noise originating from the dark current of the germanium photodetector will exceed the thermal noise while affecting the SNR of the receiver, causing receiver performance degradation. It is to be noted that the graph of Figure 2 is illustrative only and that the accumulation of dark current noise over time generally increases with the square root of time

. (Alternatively, consider the y-axis to be plotted on a matching non-linear polynomial scale). Also, at zero integration time (in which case the accumulated dark current noise is zero), the multiple axes do not cross each other.

Returning to the system 100, it is to be noted that the controller 112 can control the activation of the receiver 110 for shorter integration times (such as integration times during which the accumulated dark current noise does not exceed half of the read noise or a quarter of the read noise). Note that unless specifically required, limiting this integration time to very low levels limits the number of multiple photosensitive signals that can be detected and degrades the SNR with respect to thermal noise. It is to be noted that thermal noise levels in multiple readout circuits suitable for reading multiple noisy signals (required to collect relatively high signal levels) introduce non-negligible readout noise, which may would severely degrade the SNR.

In some implementations, the controller 112 may apply a slightly longer integration time (eg, an integration time during which the accumulated dark current noise does not exceed twice the read noise or the read noise of ×1.5).

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

To utilize germanium PDs, an exemplary system disclosed herein is adapted to overcome the relatively high dark current limitation of germanium diodes, typically in the range of about 50 uA/cm^2. This dark current problem can be overcome by using active imaging with a combination of short acquisition times and many high power laser pulses.

The use of many germanium PDs - especially but not limited to many germanium PDs fabricated using a CMOS process flow - is a much cheaper solution for uncooled SWIR imaging compared to indium gallium arsenide (InGaAs) technology. Unlike many prior art imaging systems, active imaging system 100 includes a pulsed illumination source with a short illumination duration (eg, less than 1 μS, eg, 1 to 1000 μS) and high peak power. Despite the disadvantages of such pulsed sources (e.g. non-uniform illumination, more complex readout circuitry may introduce higher levels of readout noise) and short integration times (e.g. inability to capture a large range in a single acquisition cycle) multiple distances). In the following description, several approaches are discussed for overcoming these disadvantages to provide efficient imaging systems.

Reference is now made to Figures 1B and 1C, which schematically illustrate a number of other SWIR imaging systems, numbered 100' and 100'', according to some embodiments. Like system 100, system 100' includes an active illumination source 102A and receiver 110. In some embodiments, the imaging systems 100, 100′, and 100″ further include a controller 112 and an image processor 114. In some embodiments, processing of the output of receiver 110 may be performed by image processor 114, and additionally or alternatively by an external image processor (not shown). Multiple imaging systems 100' and 100" may be many variations of imaging system 100. Any component or function discussed with respect to system 100 may be implemented in either system 100' and 100'', and vice versa.

The controller 112 is a computing device. In some embodiments, many of the functions of controller 112 are provided within illumination source 102 and receiver 110, and controller 112 is not required as a separate component. In some embodiments, the imaging systems 100' and 100'' are controlled by the controller 112, the illumination source 102 and the receiver 110 in cooperation. Additionally or alternatively, in some embodiments, the control of imaging systems 100' and 100'' may be provided by an external controller such as a vehicle electronic control unit (ECU) 120 (which may be part of a system in which the imaging system is installed). vehicle) is carried out.

Illumination source 102 is configured to emit a pulse of light 106 in the infrared (IR) region of the electromagnetic spectrum. More specifically, the light pulses 106 are in the SWIR spectral band, including wavelengths in a range of approximately 1.3 μm to 3.0 μm.

In some embodiments, such as that shown in Figure 1B, the illumination source (now labeled 102A) is an active Q-switched laser (or "active Q-switched" laser) that includes a Gain medium 122, a pump 124, mirrors (not shown), and an active QS element 126A. In some embodiments, the QS element 126A is a modulator. After electronic or optical pumping of the gain medium 122 by the pump 124, an optical pulse is released by active triggering of the QS element 126A.

In some embodiments, such as that shown in Figure 1C, the illumination source 102P is a P-QS laser comprising a gain medium 122, a pump 124, a plurality of mirrors (not shown out) and a SA 126P. After a "passive QS" optical pulse is released, SA 126P allows the laser cavity to store optical energy (from gain medium 122 pumped by pump 124) until a saturation level is reached in SA 126P. To detect the release of the passive QS pulse, a QS pulse photodetector 128 is coupled to illumination source 102P. In some embodiments, QS pulsed photodetector 128 is a germanium PD. This signal from the QS pulse photodetector 128 is used to trigger the reception process in the receiver 110 so that the receiver 110 will be enabled after a period of time appropriate to the distance of the target 104 to be imaged. This time period is derived as further described below with reference to Figures 3B, 3C, 4B and 4C.

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

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

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

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

Receiver optics 116 may include one or more optical elements, such as mirrors or lenses, arranged to collect, concentrate and optionally filter the reflected electromagnetic radiation 228, and focus the electromagnetic radiation onto on a focal plane of the receiver 110 .

Receiver 110 generates electrical signals in response to electromagnetic radiation detected by one or more germanium PDs 118 representing the imagery of the lighting scene. The signals detected by the receiver 110 may be transmitted to the internal image processor 114 or an external image processor (not shown) for processing into a SWIR image of the target 104 . In some embodiments, the receiver 110 is activated multiple times to create "time slices," each time slice covering a specific distance range. In some embodiments, image processor 114 combines these slices to create a single image with greater visual depth, such as proposed by Gruber, Tobias, et al. "Gated2depth: Real-time dense lidar (LIDAR) from gated imagery", arXiv preprint arXiv:1902.04997 (2019), incorporated by reference in its entirety.

In the automotive field, this imaged object 104 within the field of view (FOV) of the receiver 110 produced by the plurality of imaging systems 100' or 100" may be processed to provide various driver assistance and safety functions, such as: Forward Collision Warning (FCW), Lane Departure Warning (LDW), Traffic Sign Recognition (TSR) and detection of relevant entities such as pedestrians or oncoming vehicles. The generated image may also be displayed to the driver, for example on a head-up display (HUD) projected on the vehicle windshield. Additionally or alternatively, multiple imaging systems 100' or 100" may be interfaced to a vehicle ECU 120 to provide multiple images or videos to enable autonomous driving in low light levels or poor visibility conditions.

In many active imaging scenarios, a light source, such as a laser, is used in combination with an array of light receivers. Since the germanium PD operates in this SWIR band, high power optical pulses are feasible without exceeding eye safety regulations. For implementations in automotive scenarios, a typical pulse length is ~100 nanoseconds (ns), although, in certain embodiments, longer pulse durations up to about 1 microsecond are also contemplated. Considering human eye safety, a peak pulse power of ~300 kilowatts (KW) is allowed, but current laser diodes are practically unable to reach this level. Therefore, in the present system, the high power pulse is generated by a QS laser. In some embodiments, the laser is a P-QS laser to further reduce cost. In some embodiments, the laser is an active QS.

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

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

In some embodiments, the QS laser is an active QS laser. In some embodiments, the QS laser is a P-QS laser. In some embodiments, the P-QS laser includes a SA. In some embodiments, the SA is selected from the group consisting of Co2+:MgAl2O4, Co2+:Spinel, Co2+:ZnSe and other cobalt-doped crystals, V3+:YAG, doped glass, quantum dots , Semiconductor SA mirror (SESAM) and Cr4+YAG SA.

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

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

According to further embodiments, a method for active imaging includes the steps of: delivering a pulse of light through an illumination source comprising an active QS laser; and After returning to the time of the QS laser, for a limited period of time, a receiver including one or more germanium PDs is enabled to receive a reflected light pulse reflected from the target ). In some embodiments, the illumination source operates in the short wave infrared (SWIR) spectral band. In some embodiments, the limited period of time is equal to an integration time during which the dark current power of the Ge PD does not exceed a kTC noise power of the Ge PD.

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

According to further embodiments, a method for active imaging includes the steps of: pumping a P-QS laser including a SA to induce a pulse of light when the SA is saturated release; detection of the release of the light pulse by a QS pulse photodetector; based on the detected release of the light pulse, after a time sufficient for the light pulse to travel to a target and return to the QS laser, at a A receiver, including one or more germanium PDs, is enabled for a limited period of time to receive the reflected light pulse. In some embodiments, the QS laser operates in the short-wave infrared (SWIR) spectral band.

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

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

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

Referring now to Figures 3A, 3B, and 3C, a flowchart and schematic diagrams, respectively, of a method of operation of an active SWIR imaging system according to some embodiments are shown. The process 300 shown in Figure 3A is based on the system 100' as described with reference to Figure 1B. In step 302 , pump 124 of illumination source 102A is activated to pump gain medium 122 . In step 304, the active QS element 126A emits a pulse of light in the direction of a target 104 located at a distance D. In step 306, at time = T, the light pulse strikes the target 104 and generates reflected radiation back towards the system 100' and receiver 110. In step 308, after waiting for a time=T2, the receiver 110 is enabled to receive the reflected radiation. The return propagation delay T2 consists of the flight time of the pulse from illumination source 102A to target 104 plus the flight time of the light signal reflected from target 104 . Thus, for a target 104 at a distance "D" from the illumination source 102A and the receiver 110, T2 is known. The activation period Δt of the receiver 110 is determined based on the desired depth of field (DoV). The DoV is given by 2DoV=c*Δt, where c is the speed of light. A typical Δt of 100 ns provides a depth of field of 15 meters. In step 310, the reflected radiation is received by the receiver 110 for a time period Δt. The received data from the receiver 110 is processed by the image processor 114 (or an external image processor) to generate a received image. Process 300 may be repeated N times per frame, where a frame is defined as the data set transmitted from receiver 110 to image processor 114 (or an external image processor). In some embodiments, N is between 1 and 10,000.

Referring now to Figures 4A, 4B, and 4C, a flowchart and schematic diagrams, respectively, of an exemplary method of operation of an active SWIR imaging system according to some embodiments are shown. A process 400 shown in Figure 4 is based on the system 100" as described with reference to Figure 1C. In step 402, the pump 124 of the illumination source 102P is activated to pump the gain medium 122 and saturate the SA 126P. In step 404, after reaching a saturation level, SA 126P emits a pulse of light in the direction of a target 430, which is located at a distance D. In step 406, the QS pulse photodetector 128 detects the released pulse. Light pulse. In step 408, at time=T, the light pulse strikes the target 430 and generates reflected radiation back towards the system 100″ and receiver 110. In step 410, after waiting a time = T2 after a released light pulse detected by the QS pulse photodetector 128, the receiver 110 is enabled to receive the reflected radiation. The return propagation delay T2 includes the time-of-flight of the pulse from the illumination source 102P to the target 430 plus the time-of-flight of the light signal reflected from the target 430 . Thus, for a target 430 at a distance "D" from the illumination source 102P and the receiver 110, T2 is known. The activation period of Δt is determined according to the desired depth of field (DoV). In step 412, the receiver 110 receives the reflected radiation for a time period of Δt. The received data from receiver 110 is processed by image processor 114 (or by an external image processor) to generate a received image. Process 400 may be repeated N times in each frame. In some embodiments, N is between 1 and 10,000.

With reference to all of the imaging systems 100, 100' and 100", it is to be noted that any of those imaging systems may include readout circuitry to readout the charge collected by each germanium PD after the integration time to provide the detection signal for the corresponding PD. Thus, unlike LIDARs or other depth sensors, the readout process can be performed after the oscillation of the integration time and thus after the signal has changed from a wide range of Performed after multiple distances are irreversibly summed.

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

With reference to all imaging systems 100, 100' and 100", the imaging system may optionally have at least one diffractive optical element (DOE) operable to improve the intensity of the light from the pulsed illumination source prior to emitting light toward the target. Illumination uniformity. As mentioned above, a high peak power pulsed light source 102 may emit a less uniform illumination distribution on different parts of the FOV. The DOE (not illustrated) can improve the uniformity of the illumination to produce the Multiple high-quality images of the FOV. It should be noted that in many lidar systems and other depth sensors, equivalent illumination uniformity is usually not required, so for reasons of cost, system complexity, system volume, etc. , they may not contain many DOE elements. For example: in many LIDAR systems, as long as the entire FOV receives sufficient illumination (above a threshold that allows objects to be detected at a minimum required distance), certain parts of the FOV It doesn't matter if an area receives more illumination density than other parts of the FOV. The DOE of the system 100, if implemented, can be used, for example, to reduce speckle effects. It is to be noted that imaging systems 100 , 100' and 100" may also include other types of optics for directing light from the light source 102 to the FOV, such as lenses, mirrors, prisms, waveguides, etc.

As with all imaging systems 100, 100' and 100'', controller 112 may optionally be operable to enable receiver 110 to sequentially acquire a series of gated images, each gated image representing a different The detection signal of the germanium PD, and an image processor operable to combine the series of images into a single 2D image. For example: a first image can capture light from the imaging sensor between 0 and 50 meters (m), a second image can capture light from the imaging sensor between 50 and 100 meters A third image can be acquired between 100 to 125 meters of light from the imaging sensor, and the image processor 114 can combine multiple 2D images into a single 2D image. In this way, each range of distances is captured with accumulated dark current noise, which is still smaller than the readout noise introduced by the readout circuit, using more light pulses and more The cost of more calculations. The color value (eg, gray value) of each pixel of the final image may be determined according to a function (eg, a maximum value or a weighted average value) of each pixel in the plurality of gated images.

All imaging systems 100, 100', and 100", which may be an uncooled germanium-based SWIR imaging system, are operable at a distance in excess of 50 (meters) m with a 20% SWIR reflectivity (in the relevant spectral range) to detect a 1m x 1m target.

Referring to all imaging systems 100, 100' and 100", the pulsed illumination source 102 may be a QS laser operable to emit pulses having an energy of between 10 millijoules and 100 millijoules Eye-safe laser pulses. Although not required, the illumination wavelength can be selected to match a solar absorption band (eg, the illumination wavelength can be between 1.3 micrometers (μm) and 1.4 μm.

With reference to all imaging systems 100, 100' and 100", the output signal of each germanium PD used for image generation may represent a single scalar for each PD. With reference to all imaging systems 100, 100' and 100", each The PD can output an accumulated signal representing a wide range of distances. For example: some, most or all of the germanium PDs of the receiver 110 may output multiple detection signals representing each of the light reflected from 20m, 40m and 60m to the corresponding PD.

Another distinguishing feature of many imaging systems 100, 100' and 100" compared to many known art systems is that the pulsed illumination is not used to freeze rapid motion of objects in the field (unlike, for example, photographic flash illumination), and Also used for static scenes. Another distinguishing feature of the imaging systems 100, 100' and 100" compared to many known art systems is that the gating of the image is not primarily used in comparison to external noise. To avoid internal noise in the system, which is a nuisance for some known technologies such as sunlight.

It is to be noted that any of the components, features, modes of operation, system architectures, and interrelationships discussed above with respect to the various systems 100, 100', and 100" may be discussed below if necessary. Implemented in EO systems, such as systems 700, 1300, 1300', 1600, 1600', 1700, 1800, 1900, 2300, and 3600.

FIG. 5 is a flowchart illustrating a method 500 for generating SWIR images of objects in a FOV of an EO system, according to examples of the inventive subject matter. Referring to the examples set forth with respect to the previous figures, the method 500 may be performed by any of the imaging systems 100, 100', and 100″. It is to be noted that the method 500 may also be performed by any of the active imaging systems described below, such as Many systems 700, 1300, 1300', 1600, 1600', 1700, 1800, 1900, 2300, and 3600) are implemented.

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

A step 520 includes triggering the initiation of continuous signal acquisition by an imaging receiver comprising a plurality of germanium PDs (in the sense discussed above with respect to receiver 110) operable to detect the reflected of SWIR radiation. The continuous signal acquisition of step 520 means that the charge is collected continuously and irreversibly (ie, it is impossible to know what level of charge was collected at any intermediate time), and not in small increments. The triggering of step 520 can be performed before step 510 (for example: if the detection array requires an acceleration time), executed simultaneously with step 510, or after step 510 ends (for example, starting at a non-zero distance from the system) detection) is performed. Referring to the example of the drawings, step 520 may optionally be performed by the controller 112 .

Step 530 begins after triggering step 520 and includes collecting, for each of a plurality of germanium PDs, that as a result of the triggering, at least a charge induced on the corresponding germanium PD by the SWIR reflected radiation impingement is greater than Dark current of 50 μA/cm², integration time dependent dark current noise and readout noise independent of integration time. Referring to the example of the figure, step 530 may optionally be performed by the receiver 110 .

Step 540 includes: when the amount of charge collected due to dark current noise is still lower than the amount of charge collected due to accumulating irrelevant time readout noise, triggering to stop the charge collection. The integration time is the duration from step 530 until step 540 stops. Referring to the example of the drawings, step 540 may optionally be performed by the controller 112 .

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

Optionally, cessation of collection as a result of step 540 may be followed by optional step 550 of reading, by readout circuitry, a signal related to the amount of charge collected by each germanium PD of the plurality of germanium PDs, The read signal is amplified and the amplified signal is provided (optionally after further processing) to an image processor which performs the generation of the image as step 560 . Referring to the example of the figures, step 550 may optionally be performed by the readout circuit (not illustrated as above, but may be equivalent to any readout circuit discussed below, such as a readout circuit 1610, 2318, and 3630). It is to be noted that step 550 is optional, as other suitable methods of reading out the plurality of detection results from the plurality of Ge PSs may be implemented.

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

Optionally, the generating of step 560 may include generating the image based on a scalar value read for each of the plurality of Ge PDs. Optionally, the emitting of step 510 may comprise passing pulsed laser illumination (via one or more lasers) through at least one diffractive optical element (DOE) and emitting the attenuated light into the FOV , to increase the illumination uniformity of pulsed laser illumination. Optionally, the dark current is greater than 50 picoamperes per germanium PD. Optionally, the plurality of germanium PDs are a plurality of silicon germanium PDs (Si-Ge PDs), each of which includes silicon and germanium. Optionally, the emission is performed by at least one active QS laser. Optionally, the emission is performed by at least one P-QS laser. Optionally, the collection is performed while the receiver is operating at a temperature above 30°C, and the image of the FOV is processed to detect vehicles and multiple pedestrians. Optionally, the transmitting comprises transmitting illumination pulses having a pulse energy between 10 millijoules and 100 millijoules into an unprotected eye of a person at a distance of less than 1 meter without damaging the eye.

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

Figures 6 through 11C demonstrate a number of SWIR electro-optic (EO) systems and a number of P-QS lasers that can be used in such systems, as well as a number of methods for the operation and fabrication of such lasers.

FIG. 10 is a schematic functional block diagram illustrating an example of a SWIR optical system 700 according to examples of the inventive subject matter. System 700 includes at least P-QS laser 600, but may also include additional components as shown in FIG. 10, such as a sensor 702 operable to sense reflected light from the FOV of system 700, especially Reflected illumination of laser 600 reflected from a number of external objects 910 .

Referring to other examples, the sensor 702 may be implemented as an imaging receiver, a PDA, or a number of photodetection devices discussed in the present invention, such as the number of components 110, 1300, 1300', 1600, 1600', 1700, 1800, 1900, 2302 and 3610.

A processor 710 is operable to process the sensing results of the sensor 702 . The output of the process may be an image of the FOV, a depth model of the FOV, spectral analysis of one or more portions of the FOV, information on identified objects in the FOV, light on the FOV Statistics or any other kind of output. With reference to many other examples, the processor 710 may be implemented as any of the many processors discussed in this disclosure, such as the many processors 114 , 1908 , 2304 and 3620 .

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

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

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

Further and optionally, system 700 may include: temperature control (e.g., passive temperature control, active temperature control) for generally controlling a temperature of the laser or one or more components thereof (e.g., the pump diode) . Such temperature control may include, for example, a thermoelectric cooler (TEC), a fan, a heat sink, resistive heaters under pump diodes, and so on.

Further and optionally, system 700 may include another laser used to bleach at least one of GM 602 and SA 604 . Optionally, system 700 may include an internal photosensitive detector (such as one or more PDs, like PDA 706) operable to measure A time to generate a pulse. In such a case, the controller 740 is operable to send a trigger signal to the PDA 706 (or other type of camera or sensor 702) based on timing information obtained from the internal photosensitive detector 706 The reflection of laser light from many objects in the 700 field of view.

The main industry that needs a lot of lasers in the above spectral range (1.3 to 1.5 μm) is the electronics industry for optical data storage, which brings the cost of this diode laser down to a few dollars per device, per watt or even lower. However, these lasers are not suitable for other industries, such as the automotive industry, which require lasers with relatively high peak power and beam brightness and will be used under harsh environmental conditions.

It should be noted that there is no scientific consensus on the range of wavelengths considered to be part of this SWIR spectrum. However, for the purposes of the present invention, the SWIR spectrum includes electromagnetic radiation having wavelengths greater than those of the visible spectrum and which includes at least the spectral range between 1300 and 1500 nm.

Although not limited to such use, one or more P-QS lasers 600 may be used as illumination source 102 for any of imaging systems 100, 100', and 100". Lasers 600 may be used where desired In any other EO system within the SWIR range of pulsed illumination, such as many lidars, many spectrometers, many communication systems, etc. It is to be noted that the proposed laser 600 and the Various approaches to lasers allow high-volume fabrication of lasers operating in this SWIR spectral range at relatively low yield costs.

The P-QS laser 600 includes at least a crystalline gain medium (crystalline gain medium) 602 (hereinafter also referred to as "GM"), a crystal SA 604 and an optical cavity 606, and the above-mentioned crystalline material is in the optical cavity 606 Confined to allow light to propagate in the gain medium 602, the enhanced tendency produces a laser beam 612 (such as shown in FIG. 8). The cavity is also known by the terms "optical resonator" and "resonating cavity" and includes a high reflectivity mirror 608 (also known as a "high reflector"). )”) and an output coupler 610. Discussed below is the unique and novel combination of several different types of crystalline materials, and the use of various fabrication techniques to fabricate the lasers, allowing the mass production of reasonably priced lasers in this SWIR spectral range. For reasons of brevity in the present disclosure, general details known in the art regarding P-QS lasers are not provided here, but such details are readily available from a variety of sources. As known in the art, the saturable absorber of the laser acts as the Q-switch of the laser. The term "crystalline material" broadly includes any material in single or polycrystalline form.

The dimensions of the connected crystal gain medium and crystal SA may depend on the purpose of designing a particular P-QS laser 600 . In a non-limiting example, a combined length of the SA and the GM is between 5 and 15 millimeters. In a non-limiting example, the combined length of the SA and the GM is between 2 and 40 mm. In a non-limiting example, a diameter of the combination of the SA and the GM (eg if a cylinder, or confined in an imaginary such cylinder) is between 2 and 5 millimeters. In a non-limiting example, a diameter of the combination of SA and GM is between 0.5 and 10 millimeters.

The P-QS laser 600 includes a gain medium crystalline material (GMC) rigidly connected to an SA crystalline material (SAC). This rigid coupling can be achieved in any number of ways known in the art, such as using adhesives, diffusion bonding, composite crystal bonding, growing one on top of the other, and the like. However, as described below, a rigidly connected crystalline material in the form of a ceramic can be achieved using simple and inexpensive methods. It is to be noted that the GMC and the SAC material may be rigidly connected to each other directly, but may alternatively be rigidly connected to each other via an intermediate object such as another crystal. In some embodiments, both the gain medium and the SA can be realized on a monolithic crystalline material by doping different dopants (such as those discussed below with respect to SAC materials and GMCs) on the monolithic crystalline material. different parts of the crystalline material, or by co-doping a single piece of crystalline material, doping two dopants (such as a ceramic YAG co-doped with N³⁺ and V³⁺) into the same volume of crystal Material. Alternatively, the gain medium can be grown on a single crystal saturable absorbing substrate (eg, using liquid phase epitaxy, LPE). It is to be noted that the separated GMC material and SA crystalline material discussed extensively in the following disclosure, monolithic ceramic crystalline material doped with both dopants can also be used mutatis mutandis in any of the following implementations .

7A, 7B, and 7C are schematic functional block diagrams illustrating examples of P-QS lasers 600 in accordance with the presently disclosed subject matter. In Figure 7A, the two dopants are implemented on two portions of the general crystalline material 614 (serving as both GM and SA), while in Figure 7B the two dopants are implemented on Common volumes of common crystalline material 614 (where illustrated - the bulk of the common crystal) are implemented interchangeably. Alternatively, the GM and the SA may be implemented on a monolithic crystalline material doped with neodymium and at least one other material. Alternatively (such as shown in FIG. 7C), either or both of output coupler 610 and high reflectivity mirror 608 may be glued directly to the various crystalline materials (such as the GM or the SA, or the One of the two crystals).

At least one of SAC and GMC is a ceramic crystalline material which is a related crystalline material (such as doped yttrium aluminum garnet, YAG, doped vanadium ). Having a crystalline material in one (especially two) ceramic forms allows higher quantity and lower cost production. For example: instead of growing individual monocrystalline materials in a slow and limited process, polycrystalline materials can be was manufactured. One of many crystalline materials (SAC or GMC) can be sintered on top of the other, eliminating the need for complex and expensive processes such as polishing, diffusion bonding or surface activated bonding. Optionally, at least one of the GMC and SAC is polycrystalline. Optionally, both the GMC and the SAC are polycrystalline.

Referring to the combinations of crystalline materials of the GMC and the SAC that can be made, such combinations can include: a. The GMC is a ceramic neodymium-doped yttrium aluminum garnet (Nd:YAG), and the SAC is (a) a ceramic doped vanadium-doped yttrium aluminum garnet (V³⁺:YAG) or (b) a ceramic cobalt doped crystalline material. Optionally, the ceramic cobalt-doped crystalline material may be a divalent ceramic cobalt-doped crystalline material. In those alternatives, both the Nd:YAG and the SAC selected from the above group are in ceramic form. A cobalt-doped crystalline material is a crystalline material doped with cobalt. Examples include cobalt-doped spinel (Co:Co or Co²⁺:MgAl₂O₄), cobalt-doped zinc selenide (Co²⁺:ZnSe), cobalt-doped YAG (Co²⁺:YAG). Although not required, in this option the high reflectivity mirror and the SA can optionally be rigidly connected to the gain medium and the SA so that the P-QS laser is a monolithic microchip P- QS lasers (such as those shown in Figures 8 and 10). b. The GMC is ceramic neodymium-doped yttrium aluminum garnet (Nd:YAG), and the SAC is a non-ceramic SAC selected from the group of doped ceramic materials consisting of: (a) Trivalent vanadium-doped yttrium aluminum garnet (V³⁺:YAG) and (b) cobalt-doped crystalline materials. Optionally, the cobalt-doped crystalline material may be divalent cobalt-doped crystalline material. In such a case, high reflectivity mirror 608 and output coupler 610 are rigidly connected to the gain medium and the SA such that P-QS laser 600 is a monolithic microchip P-QS laser. c. The GMC is a ceramic neodymium doped rare earth element crystalline material and the SAC is a ceramic crystalline material selected from the group of doped crystalline materials consisting of: (a) trivalent vanadium doped yttrium Aluminum garnet (V³⁺:YAG) and (b) many cobalt-doped crystalline materials. Optionally, the cobalt-doped crystalline material may be divalent cobalt-doped crystalline material. Although not required, in this option the high reflectivity mirror 608 and output coupler 610 can optionally be rigidly connected to the gain medium and the SA so that the P-QS laser 600 is a monolithic microchip P-QS laser.

It is to be noted that in any one implementation, one doped crystalline material may be doped with more than one dopant. For example: the SAC may be doped with the above-disclosed main dopant and at least one other dopant material (eg at significantly lower levels). A neodymium-doped rare earth element crystalline material is a crystalline material whose unit cell contains a rare earth element (one of a well-defined group of 15 chemical elements, including the 15 lanthanides and scandium and yttrium), and doped with neodymium (eg, triple ionized neodymium) can replace the rare earth element in a portion of the unit cell. A few non-limiting examples of neodymium-doped rare earth crystalline materials that can be used in the present invention are: a. Nd:YAG (as above), Neodymium doped Potassium Yttrium Tungstate (Nd:KYW), Neodymium Doped Lithium Yttrium Fluoride (Nd:YLF), Neodymium Doped Yttrium Orthovanadate (YVO₄), among all The rare earth element is neodymium, Nd; b. Nd-doped orthovanadate ((Nd:GdVO₄), Nd-doped gallium garnet (Nd:GGG), Nd-doped potassium tungstate (Nd:KGW), all of which the rare earth element is gadolinium, Gd; c. Neodymium doped scandium lanthanum borate (Nd:LSB), wherein the rare earth element is scandium; d. Other Nd-doped rare earth element crystalline materials can be used, where the rare earth element can be yttrium, gadolinium, scandium or any other rare earth element.

The following discussion applies to any optional combination of GMCs and SACs.

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

Alternatively, the SAC may be cobalt-doped spinel (Co Co²⁺:MgAl2O4). Alternatively, the SAC may be cobalt-doped YAG (Co:YAG). Optionally, this may enable co-doping of cobalt and neodymium Nd on the same YAG. Alternatively, the SAC may be cobalt-doped zinc selenide (Co ²⁺ :ZnSe). Alternatively, the GMC may be a ceramic cobalt-doped crystalline material.

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

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

8 and 9 are a number of schematic functional diagrams illustrating a SWIR optical system 700 according to examples of the presently disclosed subject matter. As exemplified in these figures, laser 600 may include, in addition to those components discussed above, a number of additional components, such as (but not limited to): a. A light source such as a flash lamp 616 or a laser diode 618 which acts as a pump for the laser. Referring to the previous examples, the light source can be used as the pump 124 . b. Focusing optics 620 (such as a lens) for focusing light from the light source (such as 618 ) onto the optical axis of the laser 600 . c. A diffuser or other optical device 622 to manipulate the laser beam 612 after it exits the optical cavity 606 .

Optionally, SWIR optical system 700 may include optics 708 to spread the laser light over a wider FOV to improve eye safety issues in the FOV. Optionally, SWIR optical system 700 may include optics 704 to collect reflected laser light from the FOV and direct it onto the sensor 702, e.g. onto a photodetector array (PDA) 706, See Figure 10. Optionally, the P-QS laser 600 is a diode pumped solid state laser (DPSSL).

Optionally, the P-QS laser 600 includes at least one diode pump light source 872 and an optical device 620 for focusing the light of the diode pump light source into the optical resonator (optical cavity). Optionally, the light source is located on the optical axis (as an end pump). Alternatively, the light source can be rigidly attached to the high reflectivity mirror 608 or SA 604 such that the light source is part of a monolithic microchip P-QS laser. Optionally, the light source of the laser may comprise: one or more vertical cavity surface emitting laser (VCSEL) arrays. Optionally, the P-QS laser 600 includes at least one VCSEL array and optics for focusing the light of the VCSEL array into the optical resonator. The wavelength emitted by the light source (eg, the laser pump) may depend on the crystalline materials and/or dopants used in the laser. Some exemplary pump wavelengths that may be emitted by the pump include: 808 nm or about 808 nm, 869 nm or about 869 nm, about nine hundred and some nm.

The power of the laser may depend on what it is designed to do. For example: the laser output power can be between 1W and 5W. For example: the laser output power can be between 5W and 15W. For example: the laser output power can be between 15W and 50W. For example: the laser output power can be between 50W and 200W. For example: the laser output power can be higher than 200W.

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

Optionally, besides the gain medium and the SA, the laser 600 may further include: undoped YAG for preventing heat from accumulating in an absorption region of the gain medium. The undoped YAG may optionally be shaped as a cylinder (eg, a concentric cylinder) surrounding the gain medium and the SA.

FIG. 11A is a flowchart illustrating an example of a method 1100 in accordance with the presently disclosed subject matter. Method 1100 is a method for fabricating components for a P-QS laser, such as but not limited to P-QS laser 600 described above. Referring to the examples set forth with respect to the previous figures, the P-QS laser may be laser 600 . It is to be noted that any variation discussed with respect to laser 600 or with respect to a component thereof may also be discussed with respect to the components of the P-QS laser fabricated in method 1100 or with respect to a corresponding component thereof. implementation, and vice versa.

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

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

The second mold can be different from the first mold. Alternatively, the second mold may be identical to the first mold. In such a case, the at least one second powder may be inserted, for example, on top of the at least one first powder (or if already made, on top of the first green body), in Next to it, around it, and so on. The same mold (if realized) of inserting the at least one second powder into the at least one first powder may be performed before processing the at least one first powder into a first green body, after the at least one first powder processed into the first green body, or sometime during processing of the at least one first powder into the first green body.

The first powder and/or the second powder may comprise crushed YAG (or any other of the aforementioned materials, such as spinel, MgAl₂O₄, ZnSe) and doped materials (eg N³⁺, V³⁺, Co). The first powder and/or the second powder may include: the material used to make YAG (or any of the above materials, such as spinel, MgAl₂O₄, ZnSe) and doping materials (such as N³⁺, V³⁺, Co ).

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

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

Optionally, the heating of the first green body at step 1110 is performed prior to the compaction (and possibly also prior to the plugging) of the at least one second powder in step 1108 (and possibly in step 1104) . The first green body and the second green body may be heated separately (eg at different times, at different temperatures, for different durations). The first green body and the second green body may be heated together (eg in the same oven), or joined to each other during heating or not. The first green body and the second green body may be subjected to different heating regimes, which may share portions of the heating regime while being separately heated in other portions of the heating regime. For example: one or both of the first green body and the second green body can be heated separately from the other green body, and then the two green bodies can be heated together (such as after coupling, but not necessarily so) . Optionally, the heating of the first green body and the second green body comprises simultaneously heating the first green body and the second green body in a single oven. It is to be noted that, optionally, the coupling of this step 1114 is a result of simultaneous heating of the two green bodies in a single oven. It is to be noted that, optionally, the coupling of this step 1114 is accomplished by co-sintering the two green bodies after being physically connected to each other.

Step 1116 includes coupling the second crystalline material to the first crystalline material. This coupling may be performed with any coupling known in the art, several non-limiting examples of which are discussed above with respect to P-QS laser 600 . It is to be noted that this coupling may have several sub-steps, some of which may be intertwined with different steps in steps 1106, 1108, 1110 and 1112 in different ways in different embodiments. The coupling results in a single rigid crystalline body comprising the GM and the SA.

It should be noted that method 1100 may include a number of additional steps that are employed in the manufacture of crystals, particularly in the manufacture of ceramic or non-ceramic polycrystalline crystalline compounds of polycrystalline materials bonded to each other. use. A few non-limiting examples include powder preparation, binder burn-out, densification, annealing, polishing (if desired, as described below), and the like.

The GM of the P-QS laser in method 1100 (which may be the first crystalline material or the second crystalline material as described above) is a neodymium doped crystalline material. The SA of the P-QS laser in method 1100 (which may be the first crystalline material or the second crystalline material, as described above) is selected from the group of crystalline materials consisting of Group: (a) a neodymium-doped crystalline material, and (b) a doped crystalline material selected from the group consisting of trivalent vanadium-doped yttrium aluminum garnet (V³⁺:YAG) and cobalt-doped crystalline material A group of multiple doped crystalline materials. At least one of the GM and the SA is a ceramic crystalline material. Optionally, both the GM and the SA are ceramic crystalline materials. Optionally, at least one of the GM and the SA is a polycrystalline material. Optionally, both the GM and the SA are polycrystalline materials.

Although additional steps of the fabrication process recipe may be performed between different stages of the method 1100, in at least some implementations it is not necessary to polish the first material prior to bonding the second material during sintering.

Regarding the combinations of crystalline materials that can be used to fabricate the GMC and the SAC in method 1100, such combinations can include: a. The GMC is ceramic neodymium doped yttrium aluminum garnet (Nd:YAG), and the SAC is (a) ceramic trivalent vanadium doped yttrium aluminum garnet (V³⁺:YAG), or (b) a ceramic doped Cobalt crystalline material. In this alternative, both Nd:YAG and SAC selected from the above group are in ceramic form. A cobalt-doped crystalline material is a crystalline material doped with cobalt. Examples include cobalt-doped spinel (Co:Spinel or Co²⁺:MgAl₂O₄), cobalt-doped zinc selenide (Co²⁺:ZnSe). Although not required, the high reflectivity mirror and the output coupler in this option can optionally be rigidly connected to the GM and the SA so that the P-QS laser is a monolithic microchip P -QS laser. b. The GMC is a ceramic neodymium-doped yttrium aluminum garnet (Nd:YAG) and the SAC is a non-ceramic SAC selected from the group of doped ceramic materials consisting of: (a) Trivalent vanadium-doped yttrium aluminum garnet (V³⁺:YAG) and (b) various cobalt-doped crystalline materials. In such a case, the high reflectivity mirror and the output coupler are rigidly connected to the GM and the SA such that the P-QS laser is a monolithic microchip P-QS laser. c. The GMC is a ceramic neodymium-doped rare earth element crystalline material, and the SAC is selected from the group of doped crystalline materials consisting of: (a) trivalent vanadium-doped yttrium aluminum garnet (V³ ⁺:YAG) and (b) various cobalt-doped crystalline materials. Although not required, the high reflectivity mirror and the output coupler in this option can optionally be rigidly connected to the GM and the SA so that the P-QS laser is a monolithic microchip P -QS laser.

Referring generally to method 1100, it is noted that one or both of the SAC and the GMC (and optionally one or more intervening crystalline materials, if any) are transparent.

Figures 11B and 11C include several conceptual timelines for performing method 1100 in accordance with examples of the presently disclosed subject matter. To simplify the figures, it is assumed that the SA is a result of the processing of at least one first powder and the gain medium is a result of the processing of at least one second powder. As mentioned above, the roles are interchangeable.

FIG. 12A schematically shows an example of a PS, numbered 1200 , comprising a photodetector (eg, PD) 1202 controlled by a voltage controlled current source (VCCS) 1204 . It is to be noted that the voltage controlled current source 1204 may optionally be external to the PS 1200 (eg if a single VCCS 1204 supplies current to multiple PSs). VCCS 1204 is a slave current source that delivers a current proportional to a control voltage (labeled V _CTRL in the figure). The PSs and PDDs disclosed in this invention may include any suitable type of VCCS. Other (“additional”) components (not shown) of PS 1200 are collectively represented by a general block 1206 . When used for sensing, PSs such as PS 1200 and photodetectors such as photodetector 1202 may hereinafter also be referred to as "active" or "non-reference" PSs/photodetectors (Unlike PSs and photodetectors used to determine the input of the control voltage for the current source).

Another example of a PS, numbered 1200', which is an example of PS 1200, is schematically shown in Figure 12B. In PS 1200', other components 1206 are in the form of a "3T" (tri-transistor) structure. Any other suitable circuitry can be used as numerous additional components 1206 .

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

Figure 13A shows a PDD 1300 according to examples of the presently disclosed subject matter. PDD 1300 includes circuitry that can controllably match the current sourced by current source 1204 to the dark current generated by PD 1202, even if the generated dark current is not constant (varies over time). It is to be noted that the level of the dark current generated by the PD 1202 may depend on different parameters such as operating temperature and the bias voltage supplied to the PD (which may also vary from time to time).

Reducing the effect of dark current within the PS 1200 by the PDD 1300 (rather than in later stages of signal processing, whether analog or digital), enables the use of a relatively small capacitor without saturating the capacitor or degrading it The linearity of the response to the collected charge.

PDD 1300 includes a PS 1200 for detecting impinging light and a reference PS 1310, the output of which is used by additional circuitry (discussed below) to reduce or eliminate dark current in PS 1200. Influence. Like PS 1200 (and 1200'), reference PS 1310 includes a PD 1302, a VCCS 1304, and optional other circuitry ("other components", collectively referred to as 1306). In some examples, reference PS 1310 of PDD 1300 may be the same as PS 1200 of PDD 1300 . Optionally, any one or more components of PS 1310 may be identical to a corresponding component of PS 1200 . For example: PD 1302 may be substantially the same as PD 1202. For example: VCCS 1304 may be the same as VCCS 1204 . Optionally, any one or more components of PS 1310 may be different from those of PS 1200 (eg, PDs, current sources, additional circuitry). It is to be noted that substantially the same components of PS 1200 and PS 1310 (eg, PD, current source, additional circuitry) may be operated under different operating conditions. For example: different bias voltages can be supplied to multiple PDs 1202 and 1302 . For example, different components of additional components 1206 and 1306 may be manipulated using different parameters, or selectively connected/disconnected, even when their structures are substantially the same. For simplicity and clarity, the various components of PS 1310 are numbered with numbers 1302 (for the PD), 1304 (for the VCCS), and 1306 (for the additional circuitry), but this is not implied to indicate that these components are 1202, 1204 and 1206 are different.

In some examples, reference additional circuitry 1306 may be omitted or disconnected so as not to affect the dark current determination. PD 1202 can be operated under any one of the following conditions: reverse bias, forward bias, zero bias, or selectively between any two or three of the above biases (for example, by a controller such as controller 1338 discussed below). PD 1302 can be operated under any of the following conditions: reverse bias, forward bias, zero bias, or selectively between any two or three of the above biases (for example, by a controller such as controller 1338 discussed below). It is not necessary that PDs 1202 and 1302 operate at substantially the same bias voltage (eg, about -5V, about 0V, about +0.7V) (such as when testing PDD 1300, as discussed in more detail below). Alternatively, a single PS of PDD 1300 may operate sometimes as PS 1200 (detecting light from a field of view (FOV) of PDD 1300) and sometimes as PS 1310 (whose detection signal output is used to determine A control voltage of a VCCS of another PS 1200). Alternatively, the roles of the "active" PS and the reference PS of the light used to detect the impact can be swapped. The PDD 1300 also includes a control-voltage generating circuit 1340 including at least an amplifier 1318 and a plurality of electrical connections to a plurality of PSs of the PDD 1300 . The amplifier 1318 has at least two inputs: a first input 1320 and a second input 1322 . A first input 1320 of amplifier 1318 is supplied with a first input voltage (V _FI ), which may be directly controlled by a controller (implemented on PDD 1300, on an external system, or a combination thereof), or from Other voltages in the system are derived (which in turn can be controlled by the controller). A second input 1322 of amplifier 1318 is connected to the cathode of PD 1302 (referenced to PS 1310 ).

In a first use case example, the PD 1202 is maintained at a first voltage (also referred to as the "anode voltage", denoted V _A ) and a second voltage (also referred to as the "cathode voltage"). Cathode voltage (cathode voltage), denoted as an operating bias between V _C ). The anode voltage can be directly controlled by the controller (implemented on the PDD 1300, on an external system, or a combination thereof), or derived from other voltages in the system (which in turn can be controlled by the controller). The cathode voltage can be directly controlled by the controller (implemented on the PDD 1300, on an external system, or a combination thereof), or derived from other voltages in the system (which in turn can be controlled by the controller). Each of the anode voltage V _A and the cathode voltage V _C may or may not remain constant over time. For example: the anode voltage V _A can be provided by a constant source (eg from an external controller via a pad). Depending on the implementation, the cathode voltage _VC can be substantially constant or vary with time. For example, when a 3T structure is used in PS 1200 , V _C changes over time, eg due to the operation of various additional components 1206 and/or current flow from PD 1202 . _VC may optionally be determined/controlled/influenced by a number of additional components 1206 (rather than by the reference circuit).

VCCS 1204 is used to provide (feed) a current to the cathode terminal of PD 1202 to counteract the dark current generated by PD 1202 . It is to be noted that at other times, VCCS 1204 may feed other currents for other purposes (such as for calibrating or testing PDD 1300). The level of the current generated by VCCS 1204 is controlled in response to an output voltage of amplifier 1318 . The control voltage used to control VCCS 1204 , denoted as V _CTRL , may be the same as an output voltage of amplifier 1318 (as shown). Alternatively, V _CTRL may be derived from the output voltage of amplifier 1318 (eg, due to a resistance or impedance between the output of amplifier 1318 and VCCS 1204 ).

In order to counteract (or at least reduce) the effect of the dark current of PD 1202 on the output signal of PS 1200 , PDD 1300 may subject PD 1302 to substantially the same bias voltage as PD 1202 is subjected to. For example, when PD 1302 and PD 1202 are substantially identical, subjecting PD 1302 and PD 1202 to the same bias may be used. One way to supply the same bias to both PDs (1202 and 1302) is to supply the anode of PD 1302 with a voltage V _A (where the supplied voltage is denoted V _RPA , RPA stands for "reference PD anode") ”), and the cathode of the PD 1302 is supplied with a voltage V _C (where the applied voltage is denoted as V _RPC , RPC stands for “reference PD cathode”). Another way to supply the same bias voltage is to supply V _RPA =V _A +ΔV to the anode of PD 1302 and V _RPC =V _C +ΔV to the cathode of PD 1302 . Alternatively, the anode voltage V _A , the reference anode voltage V _RPA or both can be provided by an external power source (eg, via a printed circuit board (PCB) connected to the PDD 1300 ).

As mentioned above, the first input 1320 of the amplifier 1318 is supplied with the first input voltage V _FI . A second input 1322 of amplifier 1318 is connected to the cathode of PD 1302 . Operation of the amplifier 1318 reduces the voltage difference between its two inputs (1320 and 1322), thereby forcing the voltage on the second input 1322 towards the same controlled voltage supplied to the first input ( _VFI ). Referring now to FIG. 3B, where this dark current (hereinafter denoted as DC reference) on PD 1302 is represented by an arrow 1352 (the circuit shown is the same as that of FIG. 3A). During the time that PD 1202 remains in a dark condition, the current on PD 1302 is equal to the dark current of PD 1202 . PDD 1300 (or any system component connected to it or adjacent to it) may block light from reaching PD 1302, so it remains in the dark. The blocking can be done by physical barriers such as opaque barriers, by optics such as turning lenses, by electronic shutters, and the like. In the following description, it is assumed that all current on PD 1302 is dark current generated by PD 1302 . Alternatively, if the PD 1302 is subjected to light (such as many low levels of known stray light in the system), a current source can be implemented to offset the known light origin signal, or the first input voltage V _FI Can be modified to compensate (at least partially) for stray lighting. The barriers, optics, or other specialized components intended to keep light away from the PD 1302 can be implemented at the wafer level (on the same wafer on which the PDD 1300 is fabricated), can be attached to that wafer (e.g. using adhesives) , may be rigidly attached to a housing in which the wafer is mounted, and so on.

Assuming V _FI is constant (or slowly varying), the output of VCCS 1304 (represented by arrow 1354) must be equal in magnitude to the dark current of PD 1302 (DC reference), which means that VCCS 1304 is the This dark current drain provides charge carriers, allowing the voltage to remain at _VFI . Since this output of VCCS 1304 is controlled by V _CTRL in response to this output of amplifier 1318, amplifier 1318 is operated to output the desired output such that V _CTRL will control the output of VCCS 1304, which will be comparable in magnitude to that at PD 1302 This dark current on is the same.

If PD 1202 is substantially the same as PD 1302 and VCCS 1204 is substantially the same as VCCS 1304 , then the output of amplifier 1318 will also cause VCCS 1204 to provide the same level of current (DC reference) to the cathode of PD 1202 . In such a case, it is required that both PD 1202 and PD 1302 will generate a similar level of dark current in order for the output of VCCS 1204 to cancel the dark current generated by PD 1202 (hereinafter denoted as DC active PD). In order to subject both PDs (1202 and 1302) to the same bias voltage (which would cause both PDs to generate substantially the same level of dark current since both PDs are maintained at substantially the same conditions, such as temperature), the The voltage of the first input is determined in response to the anode voltage and the cathode voltage of PD 1202 and the anode voltage of PD 1302 . For example: if V _A is equal to V _RPA , then V _FI equal to V _C may be provided to the first input 1320 . It is to be noted that _VC can change over time and is not necessarily determined by a controller (eg _VC can be determined as a result of a number of additional components 1206). If PD 1202 is different from PD 1302 and/or if VCCS 1204 is different from VCCS 1304, this output of amplifier 1318 may be modified by matching electrical components (not shown) between amplifier 1318 and VCCS 1204 to provide Associated control voltage to VCCS 1204 (eg if dark current on PD 1202 is known to be linearly related to dark current on PD 1302, this output of amplifier 1318 can be modified according to the linear correlation). Another way to supply the same bias voltage is to supply V _RPA =V _A +ΔV to the anode of PD 1302 and V _RPC =V _C +ΔV to the cathode of PD 1302 .

FIG. 13C shows a photodetection device 1300 ′ comprising a plurality of PS 1200 according to examples of the presently disclosed subject matter. PDD 1300' includes all components of PDD 1300, plus many additional PS 1200s. The different PSs of the PDD 1300' are substantially identical to each other (eg, all are part of a two-dimensional PDA), so the plurality of PDs 1302 of the different PSs 1200 generate similar dark currents to each other. Therefore, the same control voltage V _CTRL is supplied to all VCCS 1204 of different PS 1200 of PDD 1300 ′, causing these VCCS 1204 to cancel (or at least reduce) the effect of the dark current generated by each PD 1202 . Any of the options discussed above with respect to PDD 1300 may be applied mutatis mutandis to PDD 1300'.

In some cases (such as _if V _C is not constant and/or unknown), a first input voltage V _FI may be provided (such as by a controller) that is selected to be used at the PD 1302 causes dark current similar to that of PD 1202.

Referring now to FIG. 14 , an exemplary PD IV curve 1400 is shown in accordance with examples of the presently disclosed subject matter. For ease of illustration, curve 1400 represents the IV curves for both PD 1302 and PD 1202, which for purposes of this description are assumed to be substantially identical and to experience the same anode voltage (i.e., for this description, _VA = _VRPA ). IV curve 1400 is relatively flat between voltages 1402 and 1404, which means that different bias voltages supplied to the associated PD between 1402 and 1404 will produce similar levels of dark current. If V _C varies over a range of cathode voltages, given a known V _A , meaning that the bias voltage on PD 1202 is limited between voltages 1402 and 1404, then supplying a V _RPC will cause This bias on V is also between voltages 1402 and 1404, will cause VCCS 1204 to output a current that is sufficiently similar to a DC active PD even though PD 1202 and PD 1302 are biased differently. In such a case, V _RPC can be within the cathode voltage range (as shown by the equivalent voltage 1414) or outside it (but still maintain the bias voltage on the PD 1302 between 1402 and 1404), As exemplified by equivalent voltage 1412 . Modifications to other configurations, such as those discussed above, may be implemented mutatis mutandis. It is to be noted that different bias voltages may also be supplied to different PDs 1202 and 1302 for other reasons. For example: different bias voltages may be supplied as part of testing or calibration of the PDA.

In real life, different PDs (or other components) of different PSs of a single PDD are not made exactly identical, and the operation of these PSs is not exactly identical to each other. In a PD array, the PDs may be somewhat different from each other, and the dark current may be different (eg, due to manufacturing differences, slight temperature differences, etc.).

FIG. 15 shows a control voltage generation circuit 1340 connected to a plurality of reference photosensitive sites 1310 (collectively 1500 ) according to examples of the invention. The circuit of FIG. 15 (also referred to as reference circuit 1500) can be used to determine one or more VCCS 1204 for one or more PS 1310 for multiple PDDs 1300, 1300' and the one or more VCCS 1204 discussed in this disclosure. A control voltage (denoted V _CTRL ) for any PDD change. In particular, the reference circuit 1500 can be used to determine a control based on data collected from multiple reference PS 1310 that differ to some extent (e.g., as a result of manufacturing inaccuracies, varying operating conditions, etc.) Voltage to counteract (or limit) the effect of dark current in one or more PS 1200 of a PDD. As mentioned earlier, the dark currents of many PDs can be different from each other even if they are similar. It is to be noted that in certain PD technologies, PDs of the same intent may feature dark currents that differ by a factor of x1.5, x2, x4 or even more. The averaging mechanism discussed here even allows compensating for such significant differences (eg in manufacturing). Where amplifier 1318 is connected to multiple reference PSs 1310 to average levels of dark current for several PSs 1310, such PSs 1310 are kept in the dark, such as using any of the mechanisms discussed above. The many voltages supplied to the different VCCS 1304 of the various PSs 1310 are shorted such that all VCCS 1304 receive substantially the same control voltage. The cathode voltages of the different reference PDs 1302 are shorted to different nets. Thus, although the currents in different reference PS 1310 are slightly different from each other (because the reference PS 1310 is slightly different from each other), the one or more PS 1200 supplied to each PDD (which can also be different from each other and from the reference PS 1310 is slightly different) and this average control voltage is accurate enough to counteract the effect of dark current on different PS 1200 in a sufficiently uniform manner. Optionally, this output voltage of a single amplifier 1318 is supplied to all PS 1200 and all reference PS 1310 . Optionally, the selected PDs for the PDD have a flat IV response (as described above, e.g. with respect to FIG. of this dark current to a very good degree. Non-limiting examples of PDDs are provided in FIGS. 16A and 16B , which include multiple reference PSs 1310 whose average output signal is used to modify the multiple output signals of multiple active PSs 1200 (e.g., to reduce the effect of dark current on the output signal). Different configurations, geometries, and numerical ratios can be implemented between the reference PSs 1310 and the active PSs 1200 of a single PDD. For example: in a rectangular photodetection array comprising multiple PSs arranged in multiple rows and multiple columns, a whole row of PSs (eg, 1,000 PSs) or a few rows or columns of PSs can be used as A number of reference PSs 1310 are (and optionally kept in the dark), while the rest of the array receives the control signal based on averaging the output of those reference PS rows. This method of generating a control current greatly reduces the effect of dark current by eliminating this average dark current, leaving only the PS-to-PS variation.

16A and 16B illustrate photodetection devices including an array of PSs and PD-based reference circuits according to examples of the present inventive subject matter. PDD 1600 (shown in FIG. 16A ) and PDD 1600′ (shown in FIG. 16B , which is a variant of PDD 1600 ) include all components of PDD 1300 , plus multiple additional PS 1200 and PS 1310 . Optionally, the different PSs of PDD 1600 (and respectively PDD 1600') are substantially identical to each other. Any of the options discussed above with respect to the plurality of PDDs 1300 and 1300' and with respect to the circuit 1500 may be applied mutatis mutandis to the PDDs 1600 and 1600'.

FIG. 16A shows a photodetector device 1600 comprising a photosensitive region 1602 (which is exposed to external light during operation of the photodetector device 1600), a region 1604, and control voltage generation circuit 1340. , the photosensitive area 1602 is provided with a plurality (array) of PS 1200, the area 1604 is provided with a plurality of reference PS 1310 kept in the dark (at least during reference current measurements, optionally at all times), the control voltage generating circuit 1340 also includes controller 1338 . The controller 1338 may control the operation of the amplifier 1318 , the voltage supplied to the amplifier 1318 and/or the operation of the plurality of reference PSs 1310 . Optionally, the controller 1338 may also control various operations of multiple PSs 1200 and/or other components of the PDD 1600 . The controller 1338 can control both the plurality of active PSs 1200 and the plurality of reference PSs 1310 to operate under the same operating conditions (eg, bias voltage, exposure time, managed readout regime). It is to be noted that any of the functions of the controller 1338 may be implemented by an external controller, such as on another processor of an EO system on which the PDD is installed, or by an automatic driving vehicle such as the PDD on which the PDD is installed. An auxiliary system of a controller) realizes. Optionally, controller 1338 may be implemented as one or more processors fabricated on the same wafer as other components of PDD 1600 (e.g., multiple PSs 1200 and 1310, amplifier 1318) . Alternatively, controller 1338 may be implemented as one or more processors located on a PCB connected to such a die. Other suitable controllers may also be implemented as controller 1338 .

Figure 16B shows a photodetector device 1600' according to examples of the presently disclosed subject matter. Photodetector device 1600' is similar to device 1600, but has components arranged in a different geometry and internal details of the different PSs are not shown. Also illustrated is readout circuitry 1610, which is used to read the plurality of detection signals from the plurality of PSs 1200 and provide them for further processing (e.g., to reduce noise, for image processing ), for storage or for any other purpose. For example: readout circuitry 1610 may sequentially and temporarily arrange the readout values of different PS 1200 (possibly after some processing by one or more processors of the PDD, not shown), before providing them for further processing, before saving or any other action. Optionally, readout circuitry 1610 may be implemented as one or more units fabricated on the same wafer as other components of PDD 1600 (eg, multiple PSs 1200 and 1310 , amplifier 1318 ). Optionally, readout circuitry 1610 may be implemented as one or more units connected to the PCB of such a wafer. Other suitable readout circuits may also be implemented as readout circuit 1610 . It is to be noted that a readout circuit such as readout circuit 1610 may be implemented in any of the photodetection devices discussed in this disclosure (eg, PDDs 1300, 1700, 1800, and 1900). Prior to an optional digitization of the signal, numerous examples of analog signal processing can be performed in the PDD (e.g., by the readout circuit 1610 or one or more processors of the corresponding PDD), including: modifying the gain ( Amplify), offset and merge (combine multiple output signals from two or more PSs). Digitization of the read data can be performed on the PDD or externally.

Optionally, PDD 1600 (or any other PDD disclosed in this invention) may include: a sampling circuit for sampling the output voltage of amplifier 1318 and/or the control voltage V _CTRL (if different), And to maintain the voltage level for at least a specified minimum time period. Such sampling circuitry may be located anywhere between the output of the amplifier 1318 and one or more of the at least one VCCS 1204 (such as at location 1620). Any suitable sampling circuitry may be used; for example, in some cases, exemplary circuitry may include multiple "sample and hold" switches. Alternatively, the sampling circuit may only be used at certain times, while performing a direct real-time readout of the control voltage at other times. For example, when the magnitudes of dark currents in the system vary slowly, it may be useful to use a sampling circuit when the PS 1310 is only shaded part of the time.

Figures 17 and 18 illustrate further photodetection devices according to examples of the presently disclosed subject matter. In a photodetection device as described above (eg, 1300, 1300', 1600, 1600'), a voltage-controlled current source is used for the plurality of active PSs 1200 and the plurality of reference PSs 1310. A current source is one example of a voltage controlled current circuit that may be used in the disclosed PDD. Another type of voltage-controlled current circuit that can be used is a voltage-controlled current-sink whose current sink is controlled in magnitude by the control voltage supplied to it. For example: a current sink can be used where the bias voltage on the plurality of PDs (1202, 1302) is opposite in direction to the bias voltage exemplified above. More generally, whenever a voltage controlled current source (1204, 1304) is discussed above, this component may be replaced by a voltage controlled current sink (designated 1704 and 1714, respectively). It is to be noted that using a current sink instead of a current source may require the use of different types of components or circuits in other parts of the corresponding PDD. For example, an amplifier 1318 used with VCCS 1204 and 1304 is different from amplifier 1718 used with voltage controlled current sinks 1704 and 1714 in terms of power, size, etc. To distinguish multiple PSs that include multiple voltage-controlled current sinks instead of multiple VCCSs, reference numerals 1200' and 1310' correspond to PSs 1200 and 1300 as discussed above.

In Figure 17, a PDD 1700 includes voltage-controlled current circuits that are voltage-controlled current drawers (in both PS 1200' and PS 1310'), and a suitable Amplifier 1718 is used instead of amplifier 1318 . All the variations discussed above for current sources apply equally to current sinks.

In FIG. 18, a PDD 1800 includes two types of voltage-controlled current circuits, voltage-controlled current sources 1204 and 1314 and voltage-controlled current sinks 1704 and 1714, and matching amplifiers 1318 and 1718. This may allow the plurality of PDs of PDD 1800 to be operated, for example, with forward or reverse bias. At least one switch (or other selection mechanism) may be used to select which reference circuit is enabled/disabled, the one based on multiple VCCS or the one based on multiple voltage control current sink reference circuits. Such a selection mechanism may be implemented, for example, to prevent two feedback regulators from operating "against" each other (eg if operating with near zero bias on the PD). Any options, interpretations or variations discussed above with respect to any of the previously discussed PDDs (eg, 1300, 1300', 1600, 1600') may apply mutatis mutandis to PDDs 1700 and 1800. In particular, the plurality of PDDs 1700 and 1800 may include the plurality of PSs 1200' and/or the plurality of reference PSs 1310', similar to those discussed above (eg, with respect to Figures 15, 16A and 16B).

It is to be noted that, in any of the photodetection devices discussed above, one or more of the PS (such as the PS of a photodetection array) may optionally be controllable to selectively act as a reference PS 1310 (such as sometimes) or as a regular PS 1200 (such as other times). Such a PS may include the circuitry required to operate in both roles. For example: It can be used if the same PDD is used in different types of electro-optical systems. Example: One system may require averaging of accuracy between 1,000 and 4,000 reference PS 1310, while another system may require a lower accuracy, which can be achieved by averaging between 1 and 1200 reference PS 1310 . In another example, as described above, when the entire PDA is dimmed and stored in a sample-and-hold circuit, averaging based on the control voltages of some (or even all) PSs can be performed, and all PSs can be used in The determined control voltage is used to detect FOV data in one or more subsequent frames.

It is to be noted that in the above discussion, for the sake of simplicity, it is assumed that the anode side of all PDs on each PDA is connected to a known (and possibly controlled) voltage, and that the plurality of detection signals and the plurality of connection of a VCCS, and additional circuitry is implemented on the cathode side. It is to be noted that, alternatively, the plurality of PDs 1202 and 1302 may instead be connected in the opposite manner (with the readout on the anode side, and so on).

With reference to all of the PDDs discussed above (e.g., 1300, 1600, 1700, 1800), it is to be noted that the plurality of PSs, the readout circuitry, the reference circuitry, and other aforementioned components (and any additional components that may be required) may be implemented on a single wafer or on more than one wafer, on one or more PCBs or another suitable type of circuitry connected to the multiple PSs, or the like.

FIG. 19 illustrates a PDD 1900 according to examples of the presently disclosed subject matter. PDD 1900 may implement any combination of features from one or more PDDs described above, and further include a number of additional components. For example: PDD 1900 may include: any one or more of the following components: a. At least one light source 1902 operable to emit light onto the FOV of the PDD 1900. Some light from light source 1902 is reflected from objects in the FOV and picked up by PSs 1200 in photosensitive area 1602 (which are exposed to external light during operation of photodetector device 1900) and used to generate An image or other model of the plurality of objects. Any suitable type of light source (eg pulsed, continuous, modulated LEDs, lasers) may be used. Optionally, operation of light source 1902 may be controlled by a controller, such as controller 1338 . b. A physical barrier 1904 is used to keep the region 1604 of the detector array in darkness. Physical barrier 1904 may be part of or external to the detector array. Physical barrier 1904 may be fixed or movable (such as a moving shutter). It is to be noted that other types of dimming mechanisms may also be used. Optionally, physical barrier 1904 (or other dimming mechanism) may darken different portions of the detection array at different times. Optionally, the operation of barrier 1904, if variable, may be controlled by a controller, such as controller 1338. c. Neglected photosensitive site 1906. It is to be noted that not all PSs of the PDA have to be used for detection (PS 1200) or as reference (PS 1310). For example: some PSs may be located in an area that is not fully dimmed and not fully lit, and thus in the generation of the image (or other type of output that is produced in response to the detection signals of the PSs 1200) be ignored. Optionally, PDD 1900 can ignore different PSs at different times. d. At least one processor 1908 for processing the plurality of detection signals output by the plurality of PS 1200. Such processing may include, for example, signal processing, image processing, spectral analysis, and the like. Optionally, the results of the processing by processor 1908 may be used to modify the operation of controller 1338 (or another controller). Alternatively, controller 1338 and processor 1908 may be implemented as a single processing unit. Optionally, the processing results of the processor 1908 may be provided to any one or more of the following: a tangible memory module 1910 for external systems (such as a remote server or a vehicle in which the PDD 1900 is installed a vehicle computer) such as via a communication module 1912, a display 1914 for displaying images or other types of results (e.g. graphs, text results from a spectrometer), another type of output interface (e.g. a speaker, not shown), and so on. It is to be noted that optionally the signals from the PSs 1310 can also be processed by the processor 1908 , eg to evaluate a condition of the PDD 1900 (eg operability, temperature). e. a memory module (memory module) 1910 for storing at least one of a plurality of detection signals output by the plurality of active PSs or by the readout circuit 1610 (for example, if different), and passed by the processor 1908 Detection information generated by processing the plurality of detection signals. f. Power source 1916 (eg, battery, alternating current (AC) power adapter, direct current (DC) power adapter). The power supply may provide power to the PSs, the amplifier, or any other component of the PDD. g. A hard casing (or any other type of structural support) 1918. h. Optics 1920 for directing light from light source 1902 (if implemented) to the FOV and/or for directing light from the FOV to the plurality of active PSs 1200. Such optics may include, for example, lenses, mirrors (fixed or movable), prisms, filters, and the like.

As mentioned above, a plurality of PDDs as described above can be used to match the control voltage that determines the current level provided by the at least one first voltage controlled current circuit (VCCC) 1204 responsible for the operation of the PDD A difference in conditions that changes the plurality of levels of dark current produced by the at least one PD 1202. For example: for a PDD including multiple PSs 1200 and multiple PSs 1320: when the PDD is operating at a first temperature, the control voltage generation circuit 1340 responds to the dark current of the multiple reference PDs 1302 to the voltage control the current circuit provides a control voltage for providing a current at a first level at a first temperature to reduce the influence of dark currents of the active PD 1202 on the outputs of the active PS 1200; and when the PDD When operating at a second temperature (higher than the first temperature), the control voltage generation circuit 1340 provides a control voltage to the voltage control current circuit responsive to the dark current of the plurality of reference PDs 1302 for providing a control voltage at a A current at a second level to reduce the influence of the dark current of the active PDs 1202 on the outputs of the active PSs 1200, so that the second level is greater in magnitude than the first level.

FIG. 20 is a flowchart of a method 2000 for compensating for dark current in a photodetector, according to examples of the inventive subject matter. The method 2000 is executed in a PDD, and the PDD includes at least: (a) multiple active PSs, each active PS includes at least one active PD; (b) at least one reference PS, including a reference PD; (c) at least one a first VCCC connected to one or more active PDs; (d) at least one reference VCCC connected to one or more reference PDs; and (e) a control voltage generation circuit connected to the active VCCC and the Refer to VCCC. For example: method 2000 may be performed in any one of multiple PDDs 1300', 1600, 1600', 1700, and 1800 (the latter two include multiple active PSs in various implementations). It is to be noted that method 2000 may include performing any of the actions or functions discussed above with respect to any component of the various aforementioned PDDs.

The method 2000 includes at least a plurality of phase(s) 2010 and 1020 . Stage 2010 includes: based on a level of dark current in the at least one reference PD, generating a control voltage that, when provided to the at least one reference VCCC, causes the at least one reference VCCC to generate a current that decreases An effect of the dark current of the reference PD on an output of the reference PS. Stage 2020 includes providing the control voltage to the at least one first VCCC, thereby causing the at least one first VCCC to generate a current that reduces a dark current of the plurality of active PDs to a plurality of outputs of the plurality of active PSs. Influence. VCCC stands for "Voltage Controlled Current Circuit", and it can be implemented as a voltage-controlled current source or a voltage-controlled current sink.

Optionally, stage 2010 is implemented using an amplifier that is part of the control voltage generation circuit. In such a case, stage 2010 comprises supplying a first input voltage to a first input of the amplifier when a second input of the amplifier is electrically connected between the reference PD and the reference voltage controlled current circuit . The amplifier can be used to continuously reduce a difference between an output of the reference voltage control circuit and the first input voltage to generate the control voltage. Optionally, both the first VCCC(s) and the reference VCCC(s) are connected to an output of the amplifier.

Where the PDD includes a plurality of different reference PDs producing different levels of dark current, stage 2010 may include generating a single control voltage based on averaging of the different dark currents of the plurality of reference PDs.

Method 2000 may include preventing light from a field of view of the PDD from reaching the reference PDs (eg, using a physical barrier or turning optics).

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

FIG. 21 is a flowchart illustrating a method 1020 for compensating dark current in a photodetection device according to examples of the inventive subject matter. Method 1020 has two phases that are performed in different temperature regimes; a first group of phases (1110 to 1116) are performed when the PDD is operating at a first temperature (T1), and when the When the PDD is operating at a second temperature (T2) higher than the first temperature, a second group of stages (1120-1126) are performed. The extent of the first temperature and the second temperature may vary in different implementations or in different instances of method 1200 . For example: the temperature difference may be at least 5°C; at least 10°C; at least 20°C; at least 40°C; at least 100°C, and so on. In particular, method 1020 may be effective at even smaller temperature differences (eg, less than 1° C.). It is to be noted that each of the first temperature and the second temperature may be implemented as a temperature range (eg spanning 0.1° C.; 1° C.; 5° C. or more). Any temperature within the second temperature range is higher than any temperature within the first temperature range (eg according to the aforementioned ranges). Method 2000 may optionally be performed (1300, 1600, etc.) in any of the PDDs discussed above. It is to be noted that method 1020 may include performing any of the actions or functions discussed above with respect to any component of the various aforementioned PDDs, and that the PDD of method 1020 may include: Any combination of one or more of the plurality of components in question.

Referring to the stages performed when the PDD operates at the first temperature (which may be a first temperature range): Stage 2110 includes determining a first control voltage based on the dark current of at least one reference PD of the PDD. Stage 2112 includes providing the first control voltage to a first VCCC coupled to at least one active PD of an active PS of the PDD, thereby causing the first VCCC to apply a first dark voltage in the active PS. The current resists the current (impose a first dark-current countering current). Step 2114 includes generating a first sense current by the active PD in response to: (a) light striking the active PD originating from an object in a field of view of the PDD, and (b) generated by the active PD the dark current. Stage 2116 includes outputting a first detection signal from the active PS in response to the first detection current and the first dark current rejection current, the first detection signal being smaller in magnitude than the first detection current, thereby compensating for the dark current against the first detection current. 1. The influence of detection signal. Method 1020 may also include an optional stage 2118 of generating at least a first image of a FOV of the PDD based on first detection signals from PSs (and optionally all) of the PDD. Stage 2118 may be performed while the PDD is at the first temperature or at a subsequent stage.

Referring to the stages performed when the PDD is operating in the second temperature (which may be a second temperature range): Stage 2120 includes determining a second control voltage based on the dark current of at least one reference PD of the PDD . Step 2122 includes providing the second control voltage to the first VCCC, thereby causing the first VCCC to apply a second dark current suppression current in the active PS; stage 2124 includes generating a second detection current by the active PD, In response to: (a) the light impact of the active PD originating from the object, and (b) the dark current generated by the active PD. Stage 2126 includes responding to the second detection current and the second dark current resisting current, outputting a second detection signal whose amplitude is smaller than the second detection current from the active PS, thereby compensating the influence of dark current on the second detection signal . A magnitude of the second dark current rejection current is greater than a magnitude of the first dark current rejection current, and possibly by any ratio greater than one. For example: the ratio may be a factor of at least two times or significantly higher, such as in the order of one, two, three (or more) magnitudes. Method 1020 may also include an optional stage 2128 of generating at least a second image of a FOV of the PDD based on second detection signals from PSs (and optionally all) of the PDD. Stage 2128 may be performed while the PDD is at the second temperature or at a subsequent stage.

Optionally, a first level of radiation (L1) impinging on the active PD from the object at a first time (t1) when the first dark current countering current is generated is substantially equal to that at the second dark current The current resists a second level of radiation (L2) impinging on the active PD from the object during a second time (t2) when the current is generated, wherein an amplitude of the second detection signal is substantially equal to the first detection signal the amplitude of the signal. It should be noted that, optionally, the PDD according to the invention can be used to detect signal levels significantly lower than its PD at certain operating temperatures (e.g. at one, two The multiple levels of dark current generated by the amplitude of one or more orders of magnitude). Thus, method 1020 can be used to generate multiple output signals of similar levels at two different temperatures, wherein the multiple dark currents are two or more orders of magnitude larger than the multiple detection signals and are significantly different from each other. Different (for example, by a factor × 2, × 10)

Optionally, the determination of the first control voltage and the determination of the second control voltage are performed by a control voltage generating circuit comprising at least one amplifier having an input electrically connected to Between the reference PD and a reference voltage controlled current circuit, the reference voltage controlled current circuit is coupled to the reference PD.

Optionally, method 1020 may further include: supplying a first input voltage to another input of the amplifier, the level of the first input voltage being determined to correspond to a bias voltage on the active PD. Optionally, method 1020 may include supplying the first input voltage such that a bias voltage on the reference PD is substantially the same as a bias voltage on the active PD. Optionally, method 1020 may include: when the multiple active PDs have multiple different dark currents, determining the first control voltage and the second control voltage based on different dark currents of multiple reference PDs of the PDD, wherein the providing of the first control voltage comprises providing the same first control voltage to a plurality of first voltage-controlled current circuits, each first voltage-controlled current circuit being coupled to a plurality of active devices of the PDD having different dark currents At least one active PD of the PDs, wherein the providing of the second control voltage includes providing the same second control voltage to the plurality of first voltage-controlled current circuits.

Optionally, multiple different active PDs simultaneously generate multiple different levels of dark current, and multiple different reference PDs simultaneously generate multiple different levels of dark current, and the control voltage generating circuit is based on multiple different levels of the second PD. The averaging of dark current provides a same control voltage to different active PDs. Optionally, method 1020 may include: using dedicated optics to direct light from the field of view to active PSs of the PDD; and reference PDs to prevent light from the field of view from reaching the PDD.

FIG. 22 is a flowchart illustrating a method 2200 for testing a photodetection device according to examples of the present inventive subject matter. For example: the test can be performed by any of the aforementioned PDDs. That is, the same circuits and architectures that can be used to reduce this effect of dark current as described above can be used for additional purposes to test multiple detection paths of multiple different PSs in real time. Alternatively, the test can be done while the PDD is in operational mode (ie not in test mode). In some implementations, some PSs can be tested while being exposed to ambient light from the FOV, even when multiple other PSs of the same PDD capture an actual image of the FOV (with or without detection for dark current). compensate). Nonetheless, it is to be noted that method 2200 may optionally be implemented in a number of other types of PDDs as well. It should also be noted that method 2200 can also optionally be implemented using circuits or architectures similar to those discussed above with respect to the aforementioned PDDs, but when the multiple PDs Not characterized by high dark current and reducing dark current is not required or performed. Method 2200 is described as being applied to a single PS, but it could be applied to some or all PSs of a PDD.

Stage 2210 of method 2200 includes providing a first voltage to a first input of an amplifier of a control voltage generation circuit, wherein the second input of the amplifier is connected to a reference PD and a second current circuit, the first Two current circuits supply current that is commanded at a level in response to an output voltage of the amplifier; thereby causing the amplifier to generate a first control voltage for a first current circuit of a PS of the PDD. Referring to the examples set forth with respect to the previous figures, the amplifier may be amplifier 1318 or amplifier 1718, and the PS may be PS 1310 or PS 1310'. Examples of where multiple first voltages may be provided to the first input are discussed below.

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

Stage 2230 of method 2200 includes providing to the first input of the amplifier a second voltage different from the first input, thereby causing the amplifier to generate a second control voltage for the first current circuit. Numerous examples of such multiple second voltages can be discussed as follows.

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

Stage 2250 of method 2200 includes determining a defect status of a detection path of the PDD based on the first output signal and the second output signal, the detection path including the PS and readout circuitry associated with the PS. A number of examples of what types of defects can be detected when using a number of different combinations of the first and second voltages are discussed below.

A first example includes using at least one of the first voltage and the second voltage to attempt to saturate the PS (such as supplying a very high current through the VCCS to the capacitance of the PS, which is different from the actual detection level irrelevant). Failure to saturate the PS (such as receiving a detection signal that is not white but may be completely black or half-tone) indicates that the associated PS or other components in its readout path (such as a PS amplifier, sampler, analog-to-digital converter) presents a problem. In such a case, the first voltage, for example, causes the amplifier to generate a control voltage that causes the first current circuit to saturate the PS. In such a case, at stage 2250, the determination of the defect status may include determining that the detection path of the PS is failing, in response to determining that the first output signal is not saturated. In such a case, the second voltage may be a voltage that does not cause the PS to saturate (eg it causes the VCCS to source no current, but only compensates for the dark current to prevent current from being collected by the capacitor). Testing whether a PS detection path can be saturated can be implemented in real time.

When attempting to saturate one or more PSs to test the PDD, method 2200 may include reading the first output signal while the PS is exposed to ambient light during a first detection frame of the PDD, where previously After determining that the detection path is operational, the determination of the fault status is performed in response to reading a saturated output signal at a second detection frame earlier than the first frame. For example: in an ongoing operation of the PDD (such as while retrieving a video), if the saturation attempt fails, a PS may be determined to be defective or unavailable after it succeeded a previous time in the same operation use. The test can be performed on a testing frame that is not part of the video, or for individual PSs where the saturated output is ignored (e.g. the pixel color corresponding to these PSs can be obtained from multiple Adjacent pixels are done), treat these PSs as spans that are not available for this frame).

A second example includes using at least one of the first voltage and the second voltage to attempt to deplete the PS (such as providing a very high opposite current to the capacitor of the PS through the VCCS, and independent of the actual detection level). Failure to deplete the PS (such as receiving a detection signal that is not black, perhaps full white or halftone) indicates a problem with the associated PS or other components in its read path. In such a case, the second voltage, for example, causes the amplifier to generate a second control voltage that causes the first current circuit to consume a detection signal. In such a case, at stage 2250, the determination of the defect status may include determining that the detection path is failing in response to determining that the second output signal is not consumed. In such a case, the first voltage may be a voltage that does not cause the PS to saturate (eg, it causes the VCCS to emit no current, but only compensates for the dark current, thereby saturating the capacitor). Testing whether a PS detection path can be consumed (eg without dimming individual PSs) can be done in real-time.

When attempting to consume one or more PSs to test the PDD, method 2200 can include reading the second output signal while the PS is exposed to ambient light in a third detection frame of the PDD, wherein the After the detection path is operational, the determination of the fault condition is performed in response to reading a consumed output signal at a fourth detection frame earlier than the third frame.

Yet another example of using method 2200 to test a PS by using supplying multiple control voltages includes supplying more than two voltages. For example: three or more different voltages may be provided to the first input of the amplifier at different times (eg in different frames). In such a case, stage 2250 may include: based on the first output signal, the second output signal and at least one other output corresponding to the third or more voltages supplied to the first input of the amplifier signal to determine the defect state of the detection path of the PDD. For example: at different times (eg, monotonically, where each voltage is greater than a previous voltage), three, four or more different voltages may be supplied to the first input of the amplifier and correspond to different The multiple output signals of the same PS of voltage may be tested to correspond to the multiple supplied voltages (eg the multiple output signals also monotonically increase in magnitude).

An example of using method 2200 to test a portion (or even all) of the PDD includes reading at least two output signals from each of the PSs of the PDD in response to the output signal of the amplifier provided to the corresponding PS. at least two different voltages, an operating state is determined for at least one first detection path based on at least two output signals of at least one PS output associated with the corresponding first detection path, and based on the corresponding second detection path The at least two output signals of at least one other PS output associated with the path determine a fault status for the at least one second detection path.

Optionally, the method 2200 can be used with multiple specified test targets when the PDD is shaded from ambient light, and/or when specified lighting is used (e.g., of a known magnitude, dedicated lighting, etc.) (e.g. black target, white target) combined execution, but not necessarily so.

Optionally, stage 2250 can be replaced by determining an operating state of the detection path. For example: this can be used to calibrate different PSs of the PDD to the same level. For example: when the PDD is darkened and does not have a dedicated target or dedicated lighting, the same voltage can be supplied to the VCCS of different PSs. Different output signals of different PSs can be compared with each other (at one or more different voltages supplied to the first input of the amplifier). Based on this comparison, multiple correction values can be assigned to different PS detection paths such that they will provide a similar output signal for similar illumination levels (modeled by the currents contained in the multiple VCCSs of different PSs). For example, it may be determined that the output of PS A should be multiplied by 1.1 to output a calibrated output signal to PS B. For example, it may be determined that an incremental signal ΔS should be added to the output of PS C to output a calibrated output signal to PS D. Non-linear corrections can also be implemented.

FIG. 23 illustrates an electro-optic (EO) system 2300 according to examples of the presently disclosed subject matter. EO system 2300 includes at least one PDA 2302 and at least one processor 2304 operable to process detection signals from PSs 2306 of the PDA. EO system 2300 may be any type of EO system that uses a PDA for detection, such as a camera, spectrometer, LIDAR, or the like.

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

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

EO system 2300 may include at least one light source 2316 operable to emit light onto the field of view (FOV) of EO system 2300 . Some light from light source 2316 is reflected from objects in the FOV and picked up by PS 2306 (at least those PSs located in a photosensitive region that were exposed to external light during the multiple frame exposure times of EO system 2300). Detecting light from objects in the FOV (whether reflections of light from light sources, reflections from other light sources, or radiated light) is used to generate an image or other model (such as a 3D depth map) of the objects in the FOV ). Any suitable type of light source may be used (eg pulsed, continuous, modulated, LED, laser). Optionally, operation of light source 2316 may be controlled by a controller, such as controller 2314.

EO system 2300 may include: a readout circuit 2318 for reading out multiple electrical detection signals from multiple different PSs 2306 . Optionally, readout circuitry 2318 may process the plurality of electrical detection signals before providing them to processor 2304 . Such preprocessing may include, for example: amplification, sampling, weighting, noise reduction, correction, digitization, capping, level adjustment, dark current compensation (amplification, sampling, weighting, denoising, correcting, digitalization, capping, level- adjustments, dark current compensation), and so on.

Additionally, EO system 2300 may include a number of additional components, such as, but not limited to, one or more of the following optional components: a. The memory module 2308 is used to store at least one of the plurality of detection signals output by the plurality of PS 2306 or by the readout circuit 2318 (if different), and is processed by the processor 2304 by processing the plurality of detection signals. The detection information generated by the signal. b. A power source 2320, such as a battery, an AC power adapter, DC power adapter, or the like. Power supply 2320 may provide power to the PDA, readout circuitry 2318 , or any other components of EO system 2300 . c. A hard shell 2322 (or any other type of structural support). d. Optics 2324 for directing light from light source 2316 (if implemented) to the FOV and/or for directing light from the FOV to PDA 2300. Such optics may include, for example, lenses, mirrors (fixed or movable), prisms, filters, and the like.

Alternatively, PDA 2302 may be characterized by a relatively high dark current (eg, a result due to the type and characteristics of its PD). Due to the high level of dark current, the capacitances of the respective PS 2306 that collect the detected charge may become saturated (partially or fully) by the dark current, with little or no dynamic range for detecting ambient light (from FOV) . Even if the readout circuitry 2318 or processor 2304 (or any other component of the system 2300) subtracts dark current levels from the detection signal (eg, normalizes the detection data), there is a lack of dynamic range for detection, This means that the resulting detection signal for each PS 2306 is too saturated to be useful for meaningfully detecting multiple ambient light levels. Since the dark current from the PD of each PS 2306 is accumulated in the capacitance (whether actual or parasitic or residual capacitance of other components of the PS) for the entire duration of the frame exposure time (FET) , thus multiple different PS 2306s with different capacitances may be rendered unusable by multiple different FETs.

FIG. 24 illustrates an example of a method 2400 for generating image information based on data from a PDA in accordance with the presently disclosed subject matter. Referring to the examples set forth with respect to the previous figures, the method 2400 may be performed by the EO system 2300 (eg, by the processor 2304, the controller 2314, etc.). In such a case, the PDA of method 2400 may optionally be PDA 2302 . Other relevant components discussed in method 2400 may be the plurality of corresponding components of EO system 2300 . Method 2400 includes altering a frame of FETs (FETs) where the PDA collects charge from its PD. This collected charge may be due to the photoelectric response to light impinging on the PDs as well as intrinsic sources within the detection system, such as due to dark current of the PDs. The impinging light may arrive from, for example, a field of view (FOV) of a video camera or other EO system on which the PDA is mounted. The FET may be controlled electronically, mechanically, or any combination thereof by controlling flash illumination duration, and the like.

It is to be noted that the FET may be a bulk FET, which is a sum of different durations where the PDA collects charge due to photoelectric activity in the PDA's PSs. A bulk FET is used where the charges collected over different durations are summed to provide a single output signal. Such a monolithic FET could be used, for example, with pulsed illumination, or with active illumination where the collection is put on hold for a short time (eg to avoid being saturated by a bright reflection in the FOV) . It is to be noted that optionally in some frames a single FET may be used, while in other frames the entire FET may be used.

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

The frame information can be provided in any format, such as a detection level (or levels) for each PS (e.g. between 0 and 1024, three RGB values, each between 0 and 255 , and the like), scalar, vector, or any other format. Optionally, the frame information (for the first frame or subsequent frames) may optionally indicate detection signals in an indirect manner (eg, information about the detection level for a given PS may be relative to a phase The level of the neighboring PS or the level relative to the same PS in a previous frame is given). The frame information may also include: additional information (eg, sequence number, time stamp, operating condition), some of which may be used in subsequent steps of method 2400 . The first frame information (and frame information for subsequent frames received in later stages of method 2400) may be received directly from the PDA, or from one or more intermediate units, such as an intermediate processor , storage units, data aggregators, and the like) are received. The first frame information (and the frame information received in later stages of the method 2400 for later frames) may include the raw data acquired by the respective PS, but may also include pre-processed data (such as in weighting, denoising, rectifying, digitizing, capping, leveling, and the like).

Stage 2404 includes identifying at least two types of PSs of the plurality of PSs of the PDD based on the first FET: a. an available PS group (referred to as "first group of usable PSs)" for the first frame, including at least a first one of the plurality of PSs of the PDA PS, a second PS and a third PS. b. an unusable PS group for the first frame (referred to as "the first unusable PS group (first group of unusable PSs)"), including at least a fourth of the plurality of PSs of the PDA PS.

This identification of stage 2404 may be implemented in different ways, and may optionally include (explicitly or implicitly) identifying (explicitly or implicitly) that each of the plurality of PSs belongs to one of the above-mentioned at least two groups. Optionally, each PS of the PDA (or each PS of a predetermined subset thereof, such as all PSs of a ROI) may be assigned to one of two complex numbers relative to the first frame, the The first available PS group or the first unavailable PS group. However, this is not necessarily required, and certain PSs may not be allocated for certain frames, or may be allocated to other multiples (such as the availability of multiple PSs based on the FET corresponding to the first frame other than parameters, such as are determined based on the collected data). Optionally, this identifying at stage 2404 may include: deciding which PSs qualify as one of the first plurality of PSs, and automatically treating the remaining PSs (or a predetermined subset thereof, such as an ROI) of the PDA as belonging to the PS. The other plural PSs of the two.

It should be noted that the identification of stage 2404 (and stages 2412 and 2402) does not necessarily reflect an actual availability state of the respective PS (in some implementations it does reflect these actual availability states). For example: a PS included in the first unavailable PS group can actually be used under the conditions of the first frame, while another PS included in the first available PS group may actually not be used in the multiple instances of the first frame. The identification of stage 2404 is an estimation or assessment of the usability of the PSs of the PDA, rather than a test of individual PSs. It is also to be noted that the availability of multiple PSs may also be estimated in stage 2404 based on other factors. For example: a pre-existing list of defective PSs can be used to exclude such PSs from being considered usable.

This identification of stage 2404 (as well as stages 2412 and 2420) may include a summation of time durations that sample PSs that include the PDD are sensitive to light based on composite FETs, and sample PS that do not include the PDD are insensitive to light A plurality of intermediate times between the plurality of durations, identifying at least one of the plurality of unavailable PS groups (and/or at least one of the plurality of available PS groups).

This identification of available and unavailable PS groups (in stages 2404, 2412, and/or 2420) may be based in part on an assessment of temperature. Optionally, method 2400 may include: processing one or more frames (particularly previous frames or the current frame) for determining a temperature estimate (e.g., by evaluating the dark current level in the dimmed PS of the FOV). Method 2400 may then include using the temperature estimate to identify an available PS group and an unavailable PS group for a later frame, which affects the generation of the corresponding image. The temperature estimate can be used to assess how quickly the dark current will saturate the dynamic range for a given PS within the duration of the associated FET. Optionally, the temperature estimate may be used to utilize a parameter of an availability model of the PS (such as the one generated in method 2500).

The timing of execution of stage 2404 may vary relative to the timing of execution of stage 2402 . For example: stage 2404 may optionally be performed before, at the same time, partly at the same time, or after performing stage 2402 . Referring to the examples of the figures, stage 2404 may optionally be performed by processor 2304 and/or controller 2314 . Examples of methods for performing this identification of stage 2404 are discussed with respect to method 1100 .

Stage 2406 includes generating a first image based on the first frame detection levels of the first usable PS group regardless of the first frame detection levels of the first unavailable PS group. The generation of the first image can be accomplished using any suitable method, and can optionally be based on additional information (such as data received from an active lighting unit, if used, from additional sensors such as humidity sensors instrument data). With reference to the examples set forth with respect to the previous figures, it is to be noted that stage 2406 may optionally be implemented by processor 2304 . It is to be noted that the generation may include various stages of processing the signals (eg weighting, noise reduction, correction, digitization, capping, level adjustment, etc.).

For the first group of unusable PSs, it is to be noted that since detection data for those PSs are ignored in the generation of the first image, replacement values may be replaced in any suitable manner (if desired). calculate. Such multiple replacement values may be calculated, for example: multiple first frame detection levels based on multiple neighboring PSs, multiple earlier detection levels based on multiple earlier frames, based on the same PS (e.g. available in one frame) or one or more neighboring PSs (eg based on kinematic analysis of the scene). For example: a Wiener filter (Wiener filter), local mean algorithms (local mean algorithms), non-local mean algorithms (non-local means algorithms), etc. can be used. With reference to the generation of a plurality of images based on the PDA data, optionally, any one or more of such images generated (such as the first image, the second image and the third image) may include: A replacement value for at least one pixel associated with a PS identified as unavailable for the corresponding image based on a detection level of at least one other adjacent PS identified as available for the corresponding image. Where non-binary availability assessments are used (and the identification of stages 2404, 2412 and/or 2420 includes identifying at least one PS as belonging to a third set of partial availability PSs), the detection signal of each such PS is partially identified To be available, it may be combined or averaged with multiple detection signals of multiple neighboring PSs and/or multiple other readings of multiple same PSs at other times when they are available (or partially available).

Optionally, the generation of the first image (and later the generation of the second image and the third image) may also include disregarding The multiple outputs of the multiple PSs used, or are determined to have a defective, non-functional, or unusable detection path. An example of an additional method for detecting defects in multiple PSs and/or multiple associated detection paths is discussed with respect to method 2200 , which may be combined with method 2400 . This output of method 2200 may be used to generate stages 2406 , 2414 and 2422 . In such a case, the method 2200 may be performed periodically and provide outputs for generating the plurality of images, or may be specifically triggered according to the method 2400 for the generation of the plurality of images.

Optionally, the generation of the first image (and the second image and the third image, later) may include: when a PS is determined to be available, based on a detection level of the PS measured, calculating A replacement value for at least one pixel associated with the PS identified as unavailable for the corresponding image. Such information can be used together with or independently of the information of multiple neighboring PSs. Using multiple detection levels from a PS at other times may include, for example: considering multiple detection levels from multiple previous frames (e.g. for multiple still scenes), using Detection information of another snapshot of image acquisition, such as a high dynamic range image (HDRI) or a multi-wavelength composite image (where several shots are taken with different spectral filters and then combined into a single image).

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

After stage 2406, the first image may then be provided to an external system (eg, a screen monitor, a memory unit, a communication system, an image processing computer). The first image can then be processed using the one or more image processing algorithms. After stage 2406, the first image can then be otherwise processed as desired.

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

Stage 2408 is performed after receiving the first frame information and includes: determining a second FET, the second FET being longer than the first FET. The determination of the second FET includes determining a duration (eg, in milliseconds, fractions thereof, or multiples thereof) of the exposure of associated PDs. Stage 2408 may also include: determining a number of additional timing parameters (such as the start time of the exposure), but this is not required. The second FET, which is longer than the first FET, may be selected for any reason. Such a reason may include, for example: any one or more of the following: overall light intensity in the FOV, light intensity in portions of the FOV, use of bracketing techniques, use of high dynamic Range photography techniques, aperture changes, and the like. The second FET can be longer than the first FET by any ratio, whether it is a relatively low value (such as ×1.1 times, ×1.5 times), is more than a few times the value (such as ×2, ×5) or higher value (such as ×20, ×100, ×5,000). Referring to the examples of the figures, stage 2408 may optionally be performed by controller 2314 and/or processor 2304 . Optionally, an external system can determine the first FET or affect the setting of the FET through the EO system 2300 (eg, a control system of a vehicle on which the EO system 2300 is installed).

It is to be noted that, optionally, at least one of stage 2408 and stage 2416 may be implemented by making a decision with such an external entity on a new FET (the second FET and/or the third FET, respectively). replace. Such an external entity may be, for example, an external controller, an external processor, an external system. It is to be noted that, optionally, at least one of stage 2408 and stage 2416 may be replaced by receiving an indication of a new FET (the second FET and/or the third FET, respectively) from an external entity. The indication of the FET may be explicit (such as a duration in milliseconds) or implicit (such as an indication of a change in aperture opening and/or exposure value (EV) corresponding to the FET, an indication of a flash duration instruct). It is to be noted that, optionally, at least one of stage 2408 and stage 2416 may be transferred to the capacitance of the PS by receiving a response to the expected dark current from an external entity (or at least a portion of the dark current, e.g. if many dark current Mitigation strategies are implemented).

Stage 2410 includes receiving a second frame of information. The second frame information includes a second frame detection level for each of the plurality of PSs of the PDA, the second frame detection level indicating an intensity of light detected in the second FET by the corresponding PS . It is to be noted that the second frame (in which the detection data for the second frame information is collected) may directly follow the first frame, but this is not required. The FETs of any one of one or more intermediate frames (if any) between the first frame and the second frame may be equal to the first FET, the second FET, or any other FET (more long or short). Referring to the example of the figure, stage 2410 may optionally be performed by processor 2304 (eg, via readout circuitry 2318).

Stage 2412 includes identifying at least two types of PSs of the PDA from the plurality of PSs of the PDD based on the second FET: a. A group of usable PSs (referred to as "second group of usable PSs") for the second frame includes the first PS. b. an unusable PS group (referred to as "a second group of unusable PSs)" for the second frame includes the second PS, the third PS and the fourth PS.

That is, since the FET of the second frame is longer, the second PS and the third PS identified as belonging to the first available PS group in stage 2404 (i.e., the aforementioned An available PS group for the frame) is identified in stage 2412 as belonging to the second unavailable PS group (ie, the aforementioned unavailable PS group for the second frame). This identification of stage 2412 may be achieved in different ways, such as any one or more of those discussed above with respect to stage 2404 . For various reasons, multiple PSs considered available for shorter FETs may be considered unavailable for longer FETs in stage 2412 . For example, if the PS has a charge storage capacity (such as capacitance) that is lower than the average charge storage capacity of the PSs in the PDA, it can be considered that the charge storage capacity of the PSs is less effective for the detection signal and None of the accumulated dark currents are sufficient. If the dark current level is maintained (e.g. constant temperature and bias across the PD), any PS that cannot be present in the first FET due to its inability to maintain sufficient dynamic range will also be identified as unusable the longer second FET.

Stage 2412 is performed after stage 2408 (because it is based on the multiple outputs of stage 2408). The timing of execution of stage 2412 may vary relative to the timing of execution of stage 2410 . For example: stage 2412 may optionally be performed before, at the same time, partly at the same time, or after performing stage 2410 . Referring to the example of the figure, stage 2412 may optionally be performed by processor 2304 . Examples of methods for performing this identification of stage 2412 are discussed with respect to method 2500 .

Stage 2414 includes generating a second image based on the second frame detection levels of the second usable PS group regardless of the second frame detection levels of the second unavailable PS group. Importantly, stage 2414 includes generating the second image while ignoring the outputs (detection levels) of at least two PSs that were used to generate the first image. Based on the FET of the first frame, the at least two PSs are identified as available and identified as available for generating the first image (ie, at least the second PS and the third PS). The generation of the second image may be accomplished using any suitable method, including any of the methods, techniques and variations discussed above with respect to the generation of the first image. With respect to the second group of unusable PSs, it is to be noted that since detection data for those PSs are ignored in the generation of the second image, replacement values may be used in any suitable manner (if required). calculate. After stage 2414, the second image can then be provided to an external system (e.g., a screen monitor, a memory unit, a communication system, an image processing computer), which can then be processed using one or more image processing algorithms. processing, or may then perform other processing as desired.

Stages 2410 to 2414 may be repeated multiple times for a number of frames captured by the photodetector sensor, whether consecutive or not. It is to be noted that in some implementations, for example if high dynamic range (HDR) imaging techniques are implemented, the second image may be generated based on multiple detection levels over several frames. In other implementations, the second image is generated by a plurality of second frame detection levels of a single frame. Multiple instances of stages 2410 and 2414 may follow a single instance of stage 2412 (eg, if the same second FET is used for several frames).

Step 2416 is executed after receiving the second frame information, and includes: determining a third FET, the third FET is longer than the first FET and shorter than the second FET. The determination of the third FET includes determining a duration (eg, in milliseconds, fractions, or multiples thereof) of the exposure to the associated PDs. Stage 2416 may also include determining a number of additional timing parameters (such as the start time of the exposure), but this is not required. The third FET may be selected for any reason, such as the reasons discussed above with respect to the decision of the second FET in stage 2408 . The third FET can be longer than the first FET by any ratio, whether it is a relatively low value (such as ×1.1 times, ×1.5 times), more than a few times the value (such as ×2, ×5), or any more High values (such as ×20, ×100, ×5,000). The third FET can be shorter than the second FET by any ratio, whether it is a relatively low value (such as ×1.1 times, ×1.5 times), more than a few times (such as ×2, ×5), or any higher value (eg ×20, ×100, ×5,000). Referring to the examples of the figures, stage 2416 may optionally be performed by controller 2314 and/or processor 2304 . Alternatively, an external system can determine the first FET or affect the setting of the FET through the EO system 2300 .

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

Stage 2420 includes identifying at least two types of PSs of the PDA from the plurality of PSs of the PDD based on the third FET: a. A usable PS group (referred to as "third group of usable PSs") for the third frame includes the first PS and the second PS. b. an unusable PS group (referred to as "a third group of unusable PSs)" for the third frame includes the third PS and the fourth PS .

That is, since the FET of the third frame is longer relative to the first frame, the second PS is identified in stage 2404 as belonging to the first group of available PSs (i.e., the aforementioned ) is identified as belonging to the third unavailable PS group (ie, the aforementioned unavailable PS group for the third frame) at stage 2420 . Since the third frame is longer than the FET of the second frame, the third PS is identified in stage 2412 as belonging to the second group of unavailable PSs (i.e., the one previously described for the second frame unavailable PS group) is identified in stage 2420 as belonging to the third available PS group (ie, the aforementioned available PS group for the third frame).

This identification of stage 2420 may be achieved in different ways, such as any one or more of those discussed above with respect to stage 2404 . For various reasons, such as: as discussed above with respect to stage 2412 , multiple PSs considered available for shorter FETs may be considered unavailable for longer FETs in stage 2420 . For various reasons, multiple PSs that are considered unavailable for the longer FET may be considered available for the shorter FET in stage 2420 . For example: if such a plurality of PSs have charge storage capabilities (such as capacitance) that are greater than those of some of the PSs in the second group of unavailable PSs, the charge storage capabilities of those different PSs may be considered to be lower than the charge storage capabilities of the PSs. A shorter integration time of the second FET is sufficient for the detection signal and the accumulated dark current.

Stage 2420 is performed after stage 2416 (because it is based on the multiple outputs of stage 2416). The timing of execution of stage 2420 may vary relative to the timing of execution of stage 2416 . For example: stage 2420 may optionally be performed before, at the same time, partly at the same time, or after performing stage 2416 . Referring to the examples of the figures, stage 2420 may optionally be performed by processor 2304 and/or controller 2314 . Examples of methods for performing the identification of stage 2420 are discussed with respect to method 1100 .

Stage 2422 includes generating a third image based on the third frame detection levels of the third usable PS group regardless of the third frame detection levels of the third unavailable PS group. Importantly, stage 2422 includes generating the third image while ignoring the outputs (detection levels) of at least one PS that were used for the generation of the first image (such as the first two PSs), simultaneously utilizing the multiple outputs of at least one PS in the generation of the second image (eg, the third PS). The generation of the third image may be accomplished using any suitable method, including any of the methods, techniques and variations discussed above with respect to the generation of the first image. Regarding the third group of unusable PSs, it is to be noted that since the detection data of these PSs are ignored in the generation of the third image, replacement values can be used in any suitable way (if required). calculate. After stage 2422, the third image may be provided to an external system (eg, a screen monitor, a memory unit, a communication system, an image processing computer). After stage 2422, the third image may be processed using one or more image processing algorithms. After stage 2422, the third image can then be otherwise processed as desired.

Optionally, the generation of one or more images (e.g., the first image, the second image, the third image) in method 2400 may be based on evaluating the cumulative dark current of at least one PS for the corresponding image. A previous stage, for example based at least on the corresponding FET, on electrical measurements in the extracted or near optical signal, and the like. For example: such measurements may include measuring dark current (or another indicative measurement) on a reference PS kept in the dark. The generation of the corresponding image may include subtracting a magnitude associated with the dark current estimate of the PS from the detection signal of one or more PSs to give a more accurate representation of the FOV of the PDA. Optionally, the compensation dark current accumulation at this stage is only performed for a plurality of available PSs of the corresponding image.

In a PDA characterized by relatively high dark current (e.g. as a result of the type and characteristics of its PDs), the capacitance of the individual PS where the sense charge is collected may become saturated by dark current (Part or all), there is almost no dynamic range for detecting ambient light (reaching from a field of view of the system). Even when means are implemented to subtract dark current levels from the detected signals (e.g. to normalize the detected data), the lack of dynamic range for detection means that the resulting signal is fully saturated, or insufficient Meaningfully detect multiple ambient light levels. Since the dark current from the PD is accumulated in the capacitance at the FET (regardless of the actual capacitors of the PSs or the parasitic or residual capacitance of other components), the method uses the FET to determine the PS available for the corresponding After collecting the charge of the dark current (or at least a relevant part thereof) for the entire FET, there will be sufficient dynamic range left in the capacitance. The identification of an unavailable group of PSs for a frame may include identifying PSs whose dynamic range is below an acceptable threshold ( or otherwise expected to fail a dynamic range adequacy criterion). Likewise, the identification of an available group of PSs for a frame may include identifying PSs having a dynamic range above an acceptable threshold given the FET of the corresponding frame (or otherwise expected to meet a dynamic range sufficiency criterion). The aforementioned two acceptable thresholds may be the same threshold or different thresholds (eg if the dynamic ranges of multiple PSs are treated differently between those thresholds, eg identified as being part of the set of available PSs for the relevant frame).

Referring generally to method 2400, it is noted that additional instances of stages 2416, 2418, 2420, and 2422 may be repeated for additional FETs (eg, a fourth FET, etc.). Such time can be longer, shorter or equal to any previously used FET. Also note that, optionally, the first FET, the second FET, and the third FET are consecutive FETs (i.e., the PDA uses no other FETs between the first FET and the third FET). FET). Alternatively, other FETs may be used between the first and third FETs.

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

A non-transitory computer-readable medium is provided for generating image information based on data from a PDA, the non-transitory computer-readable medium including instructions stored thereon when the instructions are executed on a processor When being executed, the following steps are performed: receiving first frame information, the first frame information includes a first frame detection level for each PS in a plurality of PSs of the PDA, and the first frame detection level indicates that in a first A light intensity detected by the individual PSs in a FET; based on the first FET, identifying from the plurality of PSs of the PDD: a first group of available PSs, comprising a first PS, a second PS and a third PS, and a first unavailable PS group, including a fourth PS; disregarding the multiple first frame detection levels of the first unavailable PS group, based on the first available PS The first frame detection level of the group generates a first image; after receiving the first frame information, a second FET is determined, and the FET is longer than the first FET; the second frame information is received, and the second frame The information includes a second frame detection level for each of the plurality of PSs of the PDA, the second frame detection level indicating a light intensity detected by the respective PS in a second FET; based on the first Two FETs identifying from the plurality of PSs of the PDD: a second group of available PSs, including the first PS, and a second group of unavailable PSs, including the second PS, the third PS PS and the fourth PS; disregarding the plurality of second frame detection levels of the second unavailable PS group, generating a second image based on the plurality of second frame detection levels of the second available PS group; After receiving the second frame information, determine a third FET, the third FET is longer than the first FET and shorter than the second FET; receive the third frame information, the third frame information includes information for the a third frame detection level of each PS in the plurality of PSs of the PDA, the third frame detection level indicating a light intensity detected by the respective PS in a third FET; based on the third FET, from Identify among the plurality of PSs of the PDD: a third group of available PSs, including the first PS and the second PS, and a third group of unavailable PSs, including the third PS and the fourth PS PS; and disregarding the plurality of third frame detection levels of the third unavailable PS group, generating a third image based on the plurality of third frame detection levels of the third usable PS group.

The non-transitory computer-readable medium of the preceding paragraph may include additional instructions stored thereon that, when executed on a processor, perform any of the other steps discussed above with respect to method 2400 or variants.

FIG. 25 is a flowchart illustrating a method 2500 to generate models for PDA operation in different FETs, according to examples of the presently disclosed subject matter. Identifying which of the multiple PSs belongs to a group of available PSs that provide a given FET (and possibly many additional parameters such as temperature, bias voltage on multiple PDs, capacitance of multiple PSs, etc.) can be done in The different FETs are based on a model of the behavior of each of the plurality of PSs. Such modeling may be part of method 2400, or may be performed separately prior to it. Stages 2502, 2504, and 2506 of method 2500 are performed for each of PSs of multiple PDAs, such as PDA 1602, and possibly for all PSs of the photodetector array.

Stage 2502 includes determining availability of the corresponding PS for each of a plurality of different FETs. The determination of the availability can be performed in different ways. For example: a detection signal of the PS can be compared with an expected value (such as complete darkness if the lighting level is known, or a known higher lighting level), and a detection signal in other PSs. comparisons with multiple detection levels in other multiple PSs (e.g. if all PSs are imaging a color uniform target), with multiple detection results in other multiple FETs (e.g. to determine whether the detection level at time T, eg, 200 ns, is approximately double the detection level at T/2, eg, 330 ns), and so on. The determined availability may be a binary value (such as available or unavailable), a non-binary value (such as a scalar evaluating the availability level or indicating its availability), a set of values (such as a vector), or any other suitable format. Optionally, the same multiple frame FETs are used for all of the multiple PSs, but this is not required. For example, in a non-binary availability assessment, an intermediate value between fully unavailable and fully available may indicate that at other times of availability (or partial availability), the detection signal of the corresponding PS should be consistent with Multiple detection signals from multiple neighboring PSs are combined or averaged with other readings from the same multiple PSs.

Method 2500 may include an optional stage 2504 of measuring the charge accumulation capacity and/or saturation parameters of the corresponding PS. The charge capacity can be measured in any suitable manner, such as using a power source from the PD, from another power source in the PS (such as a current source), from another power source in the PDA, or from an external power source (such as in a photodetector fabrication process). Calibration machines in manufacturing plants). Stage 2504 may be omitted, for example, where the difference is that the capacitance between different PSs is negligible or simply ignored.

Stage 2506 includes creating a usability prediction model for the corresponding PS that provides an estimate of the availability of the PS while operating different FETs that were not included in stage 2502 to actively determine the availability of the multiple FETs. The plurality of different FETs may be included in the same time span of the plurality of FETs of stage 2502 , longer from it or shorter from it. The created availability prediction model can provide different types of availability indications, such as: a binary value (such as available or unavailable), a non-binary value (such as a scalar assessing availability or its indication), a set of values (such as a vector) or any other suitable format. The availability type indicated by the model may be the same type of availability as decided in stage 2502 or a difference thereof. For example, stage 2502 may include evaluating the dark current collected in different FETs, while stage 2504 may include determining a time threshold indicating the maximum allowable FET that the PS is considered usable. Optionally, the availability model may take into account the charge accumulation capacity of individual PSs.

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

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

Stage 2506 (or stage 2508, if implemented) may be followed by optional stage 2510, which includes deciding not to use the multiple results of stage 2506 (or stage 2508, if implemented) for the phase 2502. Availability of the plurality of PSs for a FET of the plurality of FETs. For example, stage 2510 may include creating a mask (eg, a matrix) of unusable PSs for a plurality of different PSs of the photodetector array.

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

Any stage of method 2500 can be during the manufacture of the PDA (such as during factory calibration), during the operation of the system (such as during installation of an EO system including the PDA in its intended location, such as a vehicle , monitoring system, etc.), or at any other suitable time between or after these times. Different phases can be performed at different times.

Referring to method 2400 in its entirety, it is to be noted that can be extended by referring to different operating conditions at different stages (such as when different PDs are subjected to different temperatures, when multiple different bias voltages are supplied to multiple PDs). to measure the effect of dark current on multiple different PSs in multiple different FETs.

Optionally, the determining a FET (e.g., the second FET, the third FET) as part of method 2400 may include maximizing the corresponding FET while maintaining a number of unavailable PSs for the corresponding frame below a predetermined threshold. For example, to maximize signal collection, method 2400 may include setting a FET close to a threshold associated with a predetermined number of unavailable PSs (e.g., requiring at least 99% of the PDA's PSs to be available) , allowing up to 1% of the multiple PSs to be unavailable). Note that in some cases the maximization may not yield the exact maximum duration, but a duration close to it (eg above 320% or above 325% of the mathematical maximum duration) . For example: the maximum frame duration may be selected in a number of discrete predefined time spans.

For example: determining a FET as part of method 2400 may include determining a FET that is longer than other possible FETs, thereby resulting in more PSs than a previous FET, thereby making a difference with such other possible FETs. A higher number of PSs is considered unusable compared to FETs, but improves image quality in the remaining PSs. This can be useful, for example: in relatively dark conditions. It is to be noted that optionally the decision of the FET (eg by trying to maximize it) may take into account the spatial distribution of PSs which are considered unavailable in different FETs. For example: knowing that in certain areas of the PDA, a cumulative number of PSs with a high percentage of the PS, which would be considered unusable above a certain FET, may lead to a decision on a FET below that threshold , especially if this is an important part of the FOV (eg in a center of the FOV, or where a pedestrian or vehicle was identified in a previous frame).

Method 2400 may include creating a single image based on multiple detection levels in two or more frames with multiple different unavailable PS groups being detected for different FETs. For example: Three FETs can be used: ×1, ×10 and ×100. The multiple detection levels may be based on one or more PSs (eg, where the PS is available, unsaturated, and a FET detecting a non-negligible signal) or multiple detection levels of multiple neighboring PSs (eg, if no Any available detection signal, even if the corresponding PS is determined to be available, such as because the signal is negligible in such a case), is used to determine the determined color for each pixel of the image. Method 2400 may include determining multiple FETs for combining different exposures of a single image (eg, using high dynamic range imaging techniques, HDR). This determination of such FETs may be based on modeling of different PS availability in a number of different FETs, such as the model generated in method 2500 . Method 2400 may also include deciding to capture a single image in two or more different detection instances (where the plurality of detection signals are read separately in each instance and then summed), each detection instance Provide enough available PS. For example, instead of using a 2 ms FET for a single capture of a scene, method 2400 may include deciding to capture the scene twice (e.g., two 1 ms FETs, 1.5 ms and 0.5 ms FETs) such that each The number of available PSs in the exposure will exceed a predetermined threshold.

Optionally, method 2400 may include determining at least one FET based on an availability model (such as generated in method 2500) of different PSs in different FETs and at least one previous frame of saturation data captured by the PDA. . The saturation data includes information about PSs saturated in at least one FET of at least one previous frame (e.g., number of PSs, which PS, which parts of the PDA) and/or information about at least one FET in at least one previous frame Information on multiple PSs that are nearly saturated in one FET. The saturation profile may relate to the immediately preceding frame (or frames), thus it indicates the saturation behavior of a curtain imaged scene.

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

Optionally, in determining any one or more FETs, method 2400 may include determining a FET that balances extending the FET due to darkness of the FOV scene with reducing the FET to limit rendering The amount of unusable PS, which increases with longer FETs (eg, based on the method 2500 model). For example: when at the same temperature and biased across the PD (so that the dark current in each FET remains constant), stage 2408 may include deciding on a longer FET as the scene becomes darker (by a large amount) unusable PS), and stage 2416 may include deciding on a shorter FET as the scene becomes brighter again (thereby reducing the number of unusable PS). This is especially important in darker images where the availability of multiple PSs caused by dark current buildup (which is caused by temperature and operating conditions rather than lighting levels) limits the length of the FET, which will is performed if dark current accumulation does not significantly limit the dynamic range of the individual PS. In another example, during the span of time that the scene illumination remains constant, stage 2408 may include deciding to enable a longer FET due to temperature drop (thus reducing dark current and reducing the unavailable FET on each FET). PS), and stage 2416 may include: determining a shorter FET because the temperature of the PDA rises again.

FIG. 26 is a graphical representation of the execution of method 2400 for three frames taken of the same scene in different FETs, according to examples of the present inventive subject matter. The example scene consists of four concentric rectangles, each darker than the surrounding rectangles. The different figures of FIG. 26 correspond to a stage of method 2400 and are numbered with an equivalent reference numeral followed by a prime. For example: graph 2406' matches an execution of stage 2406, and so on. Each rectangle in the lower nine figures represents a single PS, or a pixel that maps directly to such a PS (in the lower three figures). In all figures, the positions of the PSs relative to the PDD remain unchanged.

As is common in many types of PDAs, the PDA from which frame information is received may include bad, defective or otherwise misbehaving PSs (also known as bad, defective or otherwise misbehaving pixels) . The term "Misbehaving PS" is broadly related to a PS that deviates from its intended response, including but not limited to: stuck, dead, hot, ignited, warm, defective And flashing PSs (stuck, dead, hot, lit, warm, defective, and flashing PSs). The abnormally behaving PS may be a single PS or a cluster of multiple PSs. Non-limiting examples of defects that may cause a PS to misbehave include: PS bump bond connectivity, troubleshooting glitches in multiplexers, vignetting, severe insensitivity of some PSs, non-linearity, signal line PS bump bond connectivity, addressing faults in the multiplexer, vignetting, severe sensitivity deficiency of some PSs, non-linearity, poor signal linearity, low full well, poor mean-variance linearity, excessive noise and high dark current). The one or more PSs identified as an unavailable PS in method 2400 may be a permanently failed PS, or a PS that is behaving abnormally based on conditions unrelated to the FET, such as due to high temperature. Such PSs can be identified as all FETs that cannot be used in method 2400 (such as PS 8012.5). However, it is to be noted that due to limited functionality and sufficiently long FETs (such as PS 8012.4), certain functional PSs (not "misbehaving") may be considered unavailable in all FETs of method 2400 . Optionally, method 2400 may include determining availability of one or more PSs of the PDA based on parameters other than FETs (eg, temperature, electrical parameters, ambient light level). It is to be noted that in such a case, due to other considerations (such as temperature), a PS rendered unusable due to FET reasons cannot usually be considered usable due to its capacitive limitation.

In the example shown: a. Probably under all conditions, the PS 8012.5 has no output signal, regardless of the amount of light hitting it in all three FETs (T₁, T₂, T₃). b. It is possible that under all conditions the PS 8012.4 outputs a saturated signal regardless of the amount of light hitting it in all three FETs (T₁, T₂, T₃). c. PS 8012.3 outputs a usable signal at the shortest FET (T₁), but an unusable (saturated) signal at the longer FETs (T₂ and T₃). d. PS 8012.2 outputs a usable signal on multiple shorter FETs (T₁ and T₃), but outputs an unusable (saturated) signal on the longest FET (T₂).

It is to be noted that other types of defects and erroneous outputs may also occur. Such errors may include, for example, outputting a highly non-linear signal response, consistently outputting a signal that is too strong, consistently outputting a signal that is too weak, outputting random or semi-random outputs, and the like. Also, many PSs (such as the first PS 8012.1) can be used for all FETs used in detection.

Returning to FIG. 23, it is to be noted that, optionally, the system 2300 may be an EO system with dynamic PS availability assessment capability. That is, the EO system 2300 may be able to alternately assign a number of different PSs as available or unavailable based on FETs and possibly other operating parameters, and only utilize multiple Signals are detected (eg according to an availability model).

In such a case, EO system 2300 includes: a. PDA 2302, which includes a plurality of PS 2306, each PS 2306 is operable to output a plurality of detection signals in different frames. The detection signal output by the corresponding PS 2306 for a frame indicates the amount of light impinging on the corresponding PS (and possibly also indicates the dark current of the PD of the corresponding PS) in a corresponding frame. b. An availability filtering module (eg, implemented as part of processor 2304, or implemented separately). The availability filter module is operable to determine for each PS 2306 that the PS is unavailable based on a first FET (which may vary between different PSs 2306), and later based on Short a second FET to determine the same PS 2306 is available. That is, PS 2306s that were unavailable at one point (and whose output was ignored while generating one or more images) may later become available again (for example, if the FET is shortened), and those PS 2306's The outputs may be useful to regenerate subsequent images. c. The processor 2304 is operable to detect levels based on the plurality of frames of the plurality of PSs 2306 to generate a plurality of images. In other configurations of the processor 2304, it is configured to: (a) exclude a first detection signal of a filtered PS when generating a first image based on a plurality of first frame detection levels, the filtered PS A first detection signal is determined by the availability filtering module to be unavailable for the first image, and (b) when detected based on a plurality of second frames captured by the PDA after capturing the plurality of first frame detection levels When generating a second image, a second detection signal of the filtered PS determined by the availability filtering module to be available for the second image is included.

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

Optionally, the controller 2314 may be configured to determine the number of FETs to use for the EO system by maximizing the number of FETs while keeping the number of unusable PSs for each frame below a predetermined threshold (e.g., as described in relation to method 2400 discussed).

Optionally, EO system 2300 may include: at least one shielded PD that is shielded (such as by a physical barrier or using deflection optics) from ambient illumination; and dedicated circuitry operable to The signal level outputs an electrical parameter indicating a level of dark current. The processor 2304 can be configured to generate a plurality of images based on the electrical parameters, based on the corresponding FETs, and based on the plurality of detection signals of the PDA, so as to compensate for different degrees of dark current accumulation in different frames.

Optionally, processor 2304 may be configured to calculate a detection level of at least one pixel of the first image associated with the filtered PS based on a detection level of the filtered PS measured when the PS is identified as available. a replacement value. Optionally, the processor 2304 may be configured to: based on the detection levels of the plurality of neighboring PSs, calculate a plurality of alternatives for the plurality of PSs when the detection signal of each PS is excluded from the generation of the plurality of images value. Optionally, processor 2304 may be operable to calculate a replacement value for at least one pixel of the first image associated with the filtered PS based on a first frame detection level of neighboring PSs.

Optionally, the processor 2304 (or availability filter module if not part of the processor) may be operable to determine a degree of availability for PSs based on a FET, the degree comprising the PDD's sampled PS pairs A sum of light-sensitive durations, excluding intermediate times between sampling durations for which PSs are light-insensitive.

Optionally, the processor 2304 can utilize an availability model generated according to the method 2500 to decide when to include and when to exclude multiple detection signals from different PSs captured at different FETs. Optionally, EO system 2300 is operable to perform method 2500 . Optionally, EO system 2300 may be configured to participate in the execution of method 2500 with an external system, such as a factory calibration machine used in the manufacture of EO system 2300 .

FIG. 27 is a flowchart illustrating an example of a method 3500 in accordance with the presently disclosed subject matter. Method 3500 is used to generate multiple images based on different subsets of multiple PSs under different operating conditions. Referring to the examples set forth with respect to the previous figures, the method 3500 may be performed by the processor 1604 , wherein the PDA of the method 3500 may optionally be the PDA 1602 . Method 3500 includes at least stages 3510, 3520, 3530, and 3540, which are repeated as a sequence for different frames captured by an array of photodetectors. This sequence can be performed entirely for every frame in a stream, but need not be, as discussed in more detail below.

The sequence begins at stage 3510, which receives frame information from the PDA indicating detection signals provided by PSs of the PDA for the frame. The frame information may include: detection level (or levels) for each PS (eg between 0 and 1024, three RGB values each between 0 and 255, etc.), or any other format. The frame information may indicate detection signals in an indirect manner (e.g., the detection level for a given PS may be given relative to the level of a neighboring PS or relative to the level of the same PS in a previous frame) Quasi-related information. The frame information may also include: additional information (such as sequence numbers, time stamps, operating conditions), some of which may be used in subsequent steps of the method 3500. The frame information received from the PDA may include: bad defective, defective or otherwise misbehaving PS.

Stage 3520 includes receiving, during the frame duration, operating condition data indicating a plurality of operating conditions of the PDA. The plurality of operating conditions may be received from different types of entities, such as any one or more of the PDA, a controller of the PDA, the at least one processor performing method 3500, one or more sensor A detector, one or more controllers of at least one processor executing method 3500, and the like. Non-limiting examples of operating conditions that may be mentioned in stage 3520 include the PDA's FETs (such as electronic or mechanical shutter, flash illumination duration, and the like), the amplification gain of the PDA or connected circuitry, Bias voltages supplied to the PDA's PDs, ambient light levels, dedicated lighting levels, image processing modes of downstream image processors, filters applied to the light (eg, spectral filtering, polarization), and the like.

Stage 3530 includes determining a defective PS group based on the operating condition data that includes at least one of the plurality of PSs and excludes a plurality of other PSs. When stage 3530 is performed for different frames in different corresponding instances of stage 3520 based on different operating condition data received for those frames, different defective PS groups are selected for different frames whose operating conditions differ from each other. However, it is possible to select the same set of defective pixels for two frames with different operating conditions (such as when the difference in operating conditions is relatively small).

It is to be noted that this decision is based on the operating condition data and not on an evaluation of the PSs themselves, therefore, the defectivity of the various PSs included in different groups is an estimate of their condition, not A statement of their actual operability conditions. Accordingly, a PS included in the defective PS group in stage 3530 is not necessarily defective or inoperable under the operating conditions indicated in the operating condition data. The decision at stage 3530 is intended to match the actual physical state of the PDA as accurately as possible.

Step 3540 includes processing the frame information to provide an image representing the frame. The processing is based on detection signals of PSs of the photodetector excluding PSs in the group of defective PSs. That is, the detection signals from the PSs of the PDA are used to generate an image representative of the field of view (or other scene, or object or objects for which light reaches the PDA), but avoid being actively involved in All detection signals of multiple PSs included in the defective PS group (which is dynamically determined based on the operating condition data in the retrieved relevant frame information as described above). Stage 3540 may optionally include calculating a plurality of replacement values to compensate for a plurality of ignored detection signals. Such calculations may include, for example, determining a replacement value for a defective PS based on detection signals of neighboring PSs. Such calculations may include, for example, determining a replacement value for a pixel of the image based on the values of neighboring pixels of the image. Any of the techniques discussed above with respect to image generation in method 2400 may also be used for image generation in stage 3540 .

An example of performing the method for two frames (a first frame and a second frame) may include, for example: a. Receive from the PDA first frame information indicating a plurality of first detection signals provided by a plurality of PSs and related to a first frame duration, the plurality of PSs including at least a first PS, a second PS and a third PS. A frame duration is the time for light aggregated by the PDA into a single image or a frame of a video. The different frame durations may be mutually exclusive, but may optionally be partially overlapping in some embodiments. b. Receiving first operating condition data indicating an operating condition of the PDA during the first frame duration. c. Determining a first defective PS group based at least on the first operating condition data, including the third PS, but excluding the first PS and the second PS. This determination may include directly determining the first defective PS group, or determining other data that implies which pixels are considered defective (e.g. determining a complement of non-defective pixels, assigning each pixel a defect level , and then set a threshold or other decision criteria). d. Processing the first frame of information based on the first defective PS group to provide a first image, such that the processing is based at least on the plurality of first detection signals of the first PS and the second PS (may be Optionally, after previous preprocessing, such as digitization, capping, level adjustment, etc.), and ignore information related to the detected signals of the third PS. e. Receive a second frame of information from the PDA, the second frame of information indicating a plurality of second detection signals provided by a plurality of detection PSs. The second frame information is related to a second frame duration other than the first frame duration. f. Receiving second operating condition data indicating operating conditions of the PDA during the second frame duration, the second operating condition data being different from the first operating condition data. It is to be noted that the second operating condition data may be received from the same source as the first operating condition data, but this is not required. g. Based on the plurality of second operating conditions, determine data of a second defective PS group, including the second PS and the third PS, but excluding the first PS. This determination may include directly determining the second defective PS group, or determining other data that implies which pixels are considered defective (e.g. determining a complement of non-defective pixels, assigning each pixel a defect level , and then set a threshold or other decision criteria). h. Processing the second frame information based on the second defective PS group to provide a second image, such that the processing of the second image information is at least based on the plurality of second detection signals of the first PS, And ignore the information related to the plurality of detection signals of the second PS and the third PS.

FIG. 28A illustrates a system 3600 and a number of exemplary target objects 3902 and 3904 according to examples of the presently disclosed subject matter. EO system 3600 includes at least a processor 3620 operable to process a plurality of detection signals from at least one PDA (possibly, but not necessarily, part of the same system) to generate an Multiple images of multiple objects. System 3600 can be implemented by a system 2300, and similar reference numbers are used (for example, in such a case, PDA 3610 can be PDA 2302, controller 3640 can be controller 2314, and so on), but this is not required. of. For the sake of brevity, not all of the descriptions provided above with respect to system 2300 are repeated, and it is noted that any combination of one or more components of system 2300 may conversely be implemented in system 3600, and vice versa. System 3600 may be a processing system (eg, a computer, a graphics processing unit) or an EO system further including PDA 3610 and optics. In the latter case, system 3600 can be any type of EO system that uses a PDA for detection, such as a camera, a spectrometer, a LIDAR, and the like. Optionally, system 2600 may include: one or more illumination sources 3650 (such as multiple lasers, multiple LEDs) for illuminating multiple objects in the FOV (such as at least the first FET and the The second FET illuminates the object). Optionally, system 3600 can include a controller 3640 that can decide different FETs for different frames based on different illumination levels of objects in the field of view of the EO system. Optionally, those different FETs may include: the first FET and/or the second FET.

Two exemplary objects are shown in Figure 28A: a dark car 3902 with a highly reflective fascia (body panels with low reflectivity), and a black rectangular panel 3904 with a white patch on top of it . It is to be noted that system 3600 is not necessarily limited to generating multiple images of multiple low reflectivity objects with multiple high reflectivity patches. However, the manner in which system 3600 generates multiple images of such objects is interesting.

Processor 3620 is configured to receive from a PDA (such as PDA 3610, if implemented) a plurality of detection results of an object comprising a high reflectivity surface surrounded on all sides by low reflectivity surfaces (indicated by multiple objects 3902 and 3904 as an example). Multiple detection results include: (a) first frame information of the object detected by the PDA in a first FET, and (b) detected by the PDA in a second FET longer than the first FET The second frame information of the object. The first frame of information and the second frame of information indicate a plurality of detection signals output by different PSs of the PDA, and the plurality of detection signals in turn indicate a plurality of light intensities of different portions of the object detected by the PDA. Some PSs detect light from low reflectivity portions of the plurality of objects, while at least one other PS detects light from the high reflectivity surface.

Based on different FETs, the processor 3620 processes the first frame information and the second frame information in different ways. FIG. 28B illustrates an exemplary first image and the second image of a plurality of objects 3902 and 3904 according to examples of the presently disclosed subject matter. When processing the first frame information, the processor 3620 processes the first frame information based on the first FET. It produces a first image comprising a bright region representing the high reflectivity surface surrounded by a dark background representing the low reflectivity surface. This is illustrated in Figure 28B as a plurality of first images 3912 and 3914 (corresponding to the plurality of objects 3902 and 3904 in Figure 28A). When the processor 3620 processes the second frame information longer than the first FET based on the second FET. Tt produces a second image that includes a dark background without a bright region. This is illustrated in Figure 28B as a plurality of second images 3922 and 3924 (corresponding to the plurality of objects 3902 and 3904 in Figure 28A).

That is, even if more light from the highly reflective surface reaches the respective PS of the photodetector in the second frame, the image output will not be brighter or saturated, but darker. Processor 3620 may determine darker colors (which have lower intensity signals, as they capture the lower reflectivity surface of the object), because it determines that the multiple signals from the multiple associated PSs are not available in that longer second FET. Optionally, the processor 3620 may be configured to discard and high The reflectivity surface corresponds to the detected light signals and is configured to calculate a dark color for at least one corresponding pixel of the second image in response to the plurality of objects captured from the plurality of neighboring PSs. Multiple light intensities detected for adjacent low-reflectivity surfaces. Optionally, the decision by the processor 3620 to discard the information of the corresponding PS is not based on the detection signal level, but based on the sensitivity of the corresponding PS to dark current (eg, limited capacitance). Optionally, when processing the second frame of information, processor 3620 may identify at least one PS that detects light from the high-reflectivity surface based on the second FET, for example similar to the plurality of identification stages of method 2400 is not available for this second frame.

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

It is to be noted that, optionally, the amount of light signal levels reaching the associated PS from the high reflectivity surface in the first FET and in the second FET may be similar. This can be accomplished by filtering the incoming light, changing an f-number of the detection optics 3670 accordingly (eg increasing the FET by a factor q and increasing the f-number by a factor q). Optionally, a first exposure value (EV) of the PDA in retrieving the first frame of information differs by less than 1% from the second EV of the PDA in retrieving the second frame of information. Optionally, the difference in FETs is the only major difference between the operating conditions between the first frame and the second frame.

The temperature of the PDA was evaluated to calibrate the usability model to different levels of dark current as discussed above. Optionally, processor 3620 may be further configured to: (a) process the detection signal reflected from the object to determine a first temperature estimate of the photodetection array in capturing the first frame of information, and Determining a second temperature estimate of the photodetection array from the first frame of information, and (b) determining to discard a plurality of detection results corresponding to the high reflectivity surface based on the second FET and the second temperature estimate.

FIG. 29 is a flow chart illustrating a method 3700 for generating image information based on data from a PDA according to examples of the inventive subject matter. Referring to the examples set forth with respect to the previous figures, it is to be noted that the method 3700 may optionally be performed by the system 3600 . Any of the variations discussed above with respect to system 3600 may apply mutatis mutandis to method 3700 . In particular, method 3700 (and at least a plurality of stages 3710 , 3720 , 3730 and 3740 ) may be performed by processor 3620 .

Stage 3710 includes receiving from the PDA a first frame of information of a black object including a white area, the first frame of information indicating the light intensity of different parts of the object detected by the PDA in a first FET. It is to be noted that the white area can be replaced by a bright area (or other highly reflective area). For example: any area with reflectivity higher than 50% can be used instead. Note that the black target could be replaced by a dark area (or other slightly reflective area). Example: Any target with a reflectivity below 10% can be used instead.

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

Stage 3730 includes receiving from the PDA a second frame of information for a black object including white areas, the second frame information being a different portion of the object detected by the PDA in a second FET longer than the first FET Indicates multiple light intensities.

Step 3740 includes processing the second frame of information based on the second FET to provide a second image including a dark background without a bright region. Optionally, stage 3740 may be implemented using any of the image generation processes discussed above with respect to any of stages 2406, 2414, and 2422 of method 2400 and the previous stage of identifying a plurality of usable and unavailable PS groups.

Regarding the execution order of method 3700 , stage 3720 is executed after stage 3710 , and stage 3740 is executed after stage 3730 . Otherwise, any suitable sequence of stages may be used. Method 3700 may also optionally include retrieving the first frame information and/or the second frame information via a PDA.

Optionally, after receiving the first frame information, the second FET can be determined before receiving the second frame information, and the second FET is longer than the first FET. Optionally, the processing of the second frame information may include: discarding the detected light intensity information of the white area based on the second FET; determining a dark color of at least one corresponding pixel of the second image in response to Multiple light intensities of multiple adjacent areas detected by the second frame information. Optionally, the processing of the second frame information may include: based on the second FET, identifying at least one PS that detects light from the white region as unavailable for the second frame. Optionally, a first exposure value (EV) of the PDA in retrieving the first frame of information may differ from a second EV of the PDA in retrieving the second frame of information by less than 1%.

Optionally, during the first frame exposure time, the accumulation of dark current on the PS associated with the low reflectivity profile leaves a usable dynamic range for the PS, and during the second frame exposure time, that The accumulation of dark current on the PS leaves an insufficient dynamic range for the PS. In such a case, the PS corresponding to the high reflectivity region cannot be used for image generation in the second image, and replacement color values can be calculated to replace the missing detection level.

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

The non-transitory computer-readable medium of the preceding paragraph may include other instructions stored thereon that, when executed on a processor, perform any of the other steps or variations discussed above with respect to method 3700 .

In the above disclosure, various systems, methods and computer code products are described, as well as the manner in which they are used to optically capture and generate high quality images. In particular, such systems, methods and computer code products can be utilized to generate multiple high quality SWIR images (or other SWIR sensing data) in the presence of high PD dark current. Such a number of PDs may be a number of germanium PDs, but not in all cases. Some of the ways in which such systems, methods and computer program products are used in a synergistic manner are discussed above, and many others are possible and considered part of the innovative subject matter of the present invention. Any of the systems discussed above may incorporate any one or more components of any one or more of the other systems discussed above to achieve higher quality results, in a more efficient or cost-effective manner, or for any Similar results were obtained for other reasons. Likewise, any of the methods discussed above may incorporate any one or more stages of any one or more of the other methods discussed above to achieve a higher quality result, achieve a similar result in a more efficient or cost-effective manner, or for any other reason.

In the following paragraphs, some non-limiting examples of such combinations are provided to demonstrate some possible synergy.

For example: imaging systems 100, 100', and 100" whose integration time is short enough to overcome the undue influence of dark current noise can implement multiple PDDs, such as multiple PDDs 1300, 1300', 1600, 1600', 1700, 1800 Included in the receiver 110 to reduce the time-invariant (direct current, DC) portion of the dark noise. In this way, the capacitance of the PSs is not overwhelmed by the time-invariant portion of the dark current not accumulated in the detection signal collapse, and the noise of the dark current does not cloud the detection signal. Multiple PDDs 1300, 1300', 1600, 1600 are implemented in any of multiple imaging systems 100, 100' and 100'' ', 1700, 1800 can be used to extend the frame exposure time to a significant degree (since the DC portion of the dark current will not be accumulated in the capacitor), while still detecting meaningful signals .

For example: imaging systems 100, 100', and 100" where the integration time is set short enough to overcome the undue influence of dark current noise may implement any one or more of methods 2400, 2500, and 3500 to determine at which Multiple PSs available for the frame exposure time, and possibly reducing the frame exposure time (which corresponds to the integration time), to further determine that a sufficient number of PSs are available. Likewise, the readout noise at a given FET The expected ratio between the expected cumulative dark current noise level and the expected availability of different PSs in such a PS can be used by the controller to set the quality of the detected signal, available pixels A balance between the number of FETs and the level of illumination required by the light source, such as laser 600. When applicable, the availability model at different FETs can also be used to determine the range of imaging systems 100, 100' and The distance of the plurality of gated images generated by 100". Further incorporation of any of the plurality of PDDs 1300, 1300', 1600, 1600', 1700, 1800 into this sensor as such an imaging system would add to the benefits discussed in the preceding paragraph.

For example: any one or more of methods 2400, 2500, and 3500 may be implemented by system 1900 (or by any EO system including any of multiple PDDs 1300, 1300', 1600, 1600', 1700, 1800). The reduction of the effects of the dark current buildup as discussed with respect to system 1900 (or any PDD mentioned) allows longer FETs to be utilized. Either method can be implemented to facilitate longer FETs, since determining which PSs are temporarily unavailable in a relatively longer FET enables the system 1900 (or one of the PDDs mentioned Another EO system) ignores these PSs and optionally replaces their detection output with data from multiple neighboring PSs.

Certain stages of the aforementioned methods may also be implemented in a computer program running on a computer system, the computer program comprising at least code portions for executing on a programmable device such as a computer system Steps of related methods are carried out when running or enabling a programmable device to perform functions of a device or system according to the present invention. Such a method can also be implemented in a computer program running on a computer system, the computer program comprising at least code parts that cause a computer to execute the steps of a method according to the invention.

A computer program is a list of instructions, such as a specific application and/or an operating system. The computer program may, for example, include one or more of the following: a subroutine, a function, a procedure, a method, an implementation, an executable application, an applet, a server, a source code, A code, a shared library/dynamically loaded library and/or other sequence of instructions designed to be executed on a computer system.

The computer program can be stored internally on a non-transitory computer readable medium. All or some of the computer programs may be provided on a computer readable medium permanently, removably or remotely coupled to an information handling system. The computer readable medium may include, for example but not limited to, any number of: magnetic storage media, including magnetic disk and magnetic tape storage media; optical storage media, such as optical disk media (e.g., CD-ROM, CD-R, etc.) ; non-volatile storage media, including semiconductor-based memory units, such as flash memory, EEPROM, EPROM, ROM; ferromagnetic digital memory; MRAM; volatile storage media, including many scratchpads, many buffers cache memory, main memory, RAM, etc.

A computer process generally includes an executable (running) program or a portion of a program, various current program values and state information, and is used by the operating system to manage the execution of the process. An operating system (OS) is software that manages the shared resources of a computer and provides programmers with an interface used to access those resources. An operating system processes system data and user input, and responds as a service to users and programs of the system by allocating and managing tasks and internal system resources.

The computer system may, for example, include at least one processing unit, associated memory, and a plurality of input/output (I/O) devices. When the computer program is executed, the computer system processes information according to the computer program, and generates results and outputs information through many I/O devices.

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

Alternatively, the illustrated examples may be implemented as circuits on a single integrated circuit or within the same device. Alternatively, the various examples may be implemented as any number of separate integrated circuits or separate devices interconnected with each other in a suitable manner. Alternatively, appropriate portions of the methods may be implemented as soft or code representations of physical circuits or as logical representations convertible to physical circuits, such as in any suitable type of hardware description language.

Other modifications, changes, and substitutions are also possible. Accordingly, the specification and drawings are to be regarded as illustrative rather than restrictive. While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is therefore to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention. It will be understood that the above-described embodiments are cited as examples only, and that various features thereof and combinations of these features may be changed and modified. While various embodiments have been shown and described, it should be understood that there is no intention to limit the invention by such disclosure, but the intention is to cover all modifications and alternative constructions falling within the scope of the invention, as described in the appended as defined in the request item.

In the claims or specification of the present invention, unless otherwise stated, adjectives such as "substantially" and "about" modify a condition or relational characteristic of one or more features of an embodiment , is understood to mean that the condition or characteristic is defined as being within acceptable tolerances for operation of the embodiment for an intended application. It should be understood that where reference is made in the claims or specification to "a" or "an" element, such reference should not be construed as that there is only one of that element.

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

100: imaging system 100': imaging system 100'': imaging system 102: illumination source 102A: illumination source 102P: illumination source 104: target 106: light pulse 108: reflected radiation 110: receiver 112: controller 114: image processing 116: Optics 118: Germanium Photodiode (PD) 120: Electronic Control Unit (ECU) 122: Gain Medium 124: Pump 126A: Q Switch (QS) Element 126P: Saturable Absorber (SA) 128: Q Switch (QS) Pulse Photodetector (PD) 226: Photodetector (PD) 228: Electromagnetic Radiation 300: Process 302: Step 304: Step 306: Step 308: Step 310: Step 400: Process 402: Step 404: Step 406: Step 408: Step 410: Step 412: Step 430: Target 500: Method 510: Step 520: Step 530: Step 540: Step 550: Step 560: Step 600: Laser 602: Crystal Gain Medium (GM) 604 : Saturable Absorber (SA) 606: Optical Cavity 608: High Reflectivity Mirror 610: Output Coupler 612: Laser Beam 614: Common Crystalline Material 616: Flash Lamp 618: Laser Diode 620: Focusing Optics 622: Diffuser or other optics 700: shortwave infrared (SWIR) optical system 702: sensor 704: optics 706: photodetector array (PDA) 708: optics 710: processor 712: controller 910: object 1100: Method 1102: Step 1104: Step 1106: Step 1108: Step 1110: Step 1112: Step 1114: Step 1200: Photosensitive Site (PS) 1200': Photosensitive Site (PS) 1202: Photodetector (PD) 1204: Voltage Controlled Current Source (VCCS) 1206: Other Components 1300: Photodetection Device (PDD) 1300': Photodetection Device (PDD) 1302: Photodetector (PD) 1304: Voltage Controlled Current Source (VCCS) 1306: Other Components 1310: Photosensitive point (PS) 1310': photosensitive point (PS) 1318: amplifier 1320: first input 1322: second input 1338: controller 1340: control voltage generation circuit 1400: curve 1402: voltage 1404: voltage 1412: etc. Effective voltage 1414: equivalent voltage 1500: reference circuit 1600: photoelectric detection device (PDD) 1600': photoelectric detection device (PDD) 1602: photosensitive area 1604: area 1610: readout circuit 1620: position 1700: photoelectric detection device (PDD ) 1704: Voltage controlled current drawer 1714: Voltage controlled current drawer 1718: Amplifier 1800: Photodetection device (PDD) 1900: Photodetection device (PDD) 1902: Light source 1904: Physical barrier 1906: Ignored photosensitive site 1908 : Processor 1910: Memory Module 1912: Communication Module 1914: Display 1916: Power Supply 1918: Hard Case 1920: Optics 2000: Method 2010: Stage 2020: Stage 2100: Method 2112: Stage 2114: Stage 2116: Stage 2118 : stage 2120: stage 2122: step 2124: stage 2126: stage 2128: stage 2200: method 2210: stage 2220: stage 2230: stage 2240: stage 2250: stage 2300: electro-optic (EO) system 2302: photodetector array (PDA ) 2304: processor 2306: photosensitive site (PS) 2308: memory module 2310: communication module 2312: display 2314: controller 2316: light source 2318: readout circuit 2320: power supply 2322: hard case 2324: optical device 2400: method 2402: stage 2402': graph 2404: stage 2404': graph 2406: stage 2406': graph 2408: stage 2408': graph 2410: stage 2410': graph 2412: stage 2412': graph 2414: stage 2414' :image 2416:stage 2416':image 2418:stage 2418':image 2420:stage 2420':image 2422:stage 2422':image 2500:method 2502:stage 2504:stage 2506:stage 2508:stage 2510:stage 3500: Method 3510: Stage 3520: Stage 3530: Stage 3540: Stage 3600: System 3610: Photodetector Array (PDA) 3620: Processor 3630: Readout Circuitry 3640: Controller 3650: Illumination Source 3662: Memory 3670: Detection Optics Device 3700: Method 3710: Stage 3720: Stage 3730: Stage 3740: Stage 3902: Exemplary Target Object 3904: Exemplary Target Object 3912: First Image 3914: First Image 3922: Second Image 3924: Second Image 8012( 1): 1st photosensitive site 8012 (2): 2nd photosensitive site 8012 (3): 3rd photosensitive site 8012 (4): 4th photosensitive site 8012 (5): 5th Photosensitive site A: range D: distance DoV: depth of field FOV: field of view T: time _T2 : time V _A : anode supply voltage V _C : cathode supply voltage V _CTRL : control voltage V _FI : first input voltage V _RPA : Reference anode voltage Δt: enable period

Non-limiting examples of embodiments disclosed herein are described below with reference to the figures listed following this paragraph. Identical structures, elements or parts that appear in more than one figure may be labeled with the same numerals in all the figures in which they appear. The drawings and descriptions are intended to illustrate and illustrate the embodiments disclosed herein and should not be considered limiting in any way. All figures show apparatuses or flowcharts according to various examples of the presently disclosed subject matter. In the attached picture: [FIG. 1A]: Is a schematic block diagram illustrating an active SWIR imaging system. [FIG. 1B]; is a schematic block diagram illustrating an active SWIR imaging system. [FIG. 1C]: Is a schematic block diagram illustrating an active SWIR imaging system. [FIG. 2]: is an exemplary graph illustrating the relative magnitude of noise power after different durations of integration times in a SWIR imaging system. [FIG. 3A]: A flowchart illustrating a method of operation of an active SWIR imaging system according to some embodiments. [FIG. 3B]: A schematic diagram showing a method of operation of an active SWIR imaging system according to some embodiments. [FIG. 3C]: A schematic diagram showing a method of operation of an active SWIR imaging system according to some embodiments. [FIG. 4A]: A flowchart illustrating an exemplary method of operation of an active SWIR imaging system. [Fig. 4B]: A schematic diagram illustrating an exemplary method of operation of an active SWIR imaging system. [Fig. 4C]: A schematic diagram illustrating an exemplary method of operation of an active SWIR imaging system. [FIG. 5]: is a flowchart illustrating a method for generating multiple SWIR images of multiple objects in a FOV of an EO system; [FIG. 6]: is a schematic functional block diagram showing an example of a SWIR optical system. [FIG. 7A]: is a schematic functional block diagram illustrating an example of a P-QS laser. [FIG. 7B]: is a schematic functional block diagram illustrating an example of a P-QS laser. [FIG. 7C]: is a schematic functional block diagram illustrating an example of a P-QS laser. [Fig. 8]: is a schematic functional diagram illustrating a SWIR optical system. [Fig. 9]: is a schematic functional diagram illustrating a SWIR optical system. [FIG. 10]: is a schematic functional block diagram illustrating an example of a SWIR optical system. [FIG. 11A]: is a flowchart illustrating an example of a method for manufacturing components of a P-QS laser. [FIG. 11B]: Is a conceptual timeline for performing a method for making components of a P-QS laser is illustrated. [FIG. 11C]: Is a conceptual timeline for performing a method for making components of a P-QS laser is illustrated. [FIG. 12A]: Schematically shows that a PS includes a PD controlled by a voltage-controlled current source. [FIG. 12B]: Schematically shows a PS including a PD controlled by a voltage-controlled current source in a "3T" configuration. [FIG. 13A]: Shows a photodetection device (PDD) including a PS and circuitry operable to reduce the effects of dark current. [FIG. 13B]: Shows a photodetection device (PDD) including a PS and circuitry operable to reduce the effects of dark current. [FIG. 13C]: Shows a PDD including a plurality of PSs and circuits operable to reduce the influence of dark current. [Fig. 14]: Shows an exemplary PD IV curve and possible operating voltage of a PDD. [FIG. 15]: Shows a control voltage generating circuit connected to a plurality of reference optical sites. [FIG. 16A]: Shows a PDD including an array of PSs and a reference circuit based on the PDs. [FIG. 16B]: Shows a PDD including an array of PSs and a reference circuit based on the PDs. [FIG. 17]: Shows a PDD each including a PS and circuits operable to reduce the influence of dark current. [FIG. 18]: Shows a PDD each including a PS and circuits operable to reduce the influence of dark current. [Fig. 19]: This diagram illustrates a PDD, which includes optical devices, a processor, and multiple additional components. [FIG. 20]: Is a flowchart illustrating a method for compensating dark current in a photodetector. [FIG. 21]: Is a flowchart illustrating a method for compensating dark current in a photodetector. [FIG. 22]: Is a flowchart illustrating a method for testing a photodetector. [FIG. 23]: Is a diagram illustrating an EO system according to some embodiments. [Fig. 24]: It is an example of a method for generating image information based on data from a photodetector array (PDA). [FIG. 25]: Is a flowchart illustrating a method for generating a model for PDA operation at different frame exposure times. [FIG. 26]: Is a graphical representation illustrating a method for generating a model for PDA operation at different frame exposure times performed on different frames of the same scene captured at different frame exposure times. [FIG. 27]: is a flowchart illustrating an example of a method for generating multiple images based on different subsets of multiple PSs under different operating conditions. [FIG. 28A]: Is a diagram illustrating an EO system and exemplary target objects. [FIG. 28B]: Is a diagram illustrating an EO system and exemplary target objects. [Fig. 29]: It is a flowchart illustrating a method for generating image information based on data from a PDA.

It will be understood that for simplicity and clarity of illustration, various elements shown in the drawings have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

600:Laser

602: Crystal Gain Media (GM)

604: Saturable absorber (SA)

608: high reflectivity mirror

610: output coupler

612:Laser Beam

618:Laser diode

700:Short Wave Infrared (SWIR) Optical System

702: sensor

704: Optics

706: Photodetector Array (PDA)

708: Optics

710: Processor

712: Controller

910: object

Claims (27)

A passive Q-switched (P-QS) laser comprising: a gain medium comprising a gain medium crystalline (GMC) material comprising a ceramic neodymium-doped yttrium aluminum garnet (Nd:YAG); a saturable absorber (SA) rigidly coupled to the gain medium, the saturable absorber comprising a sintered ceramic saturable absorber crystalline (SAC) material selected from A group of doped ceramic materials consisting of: a trivalent vanadium-doped yttrium aluminum garnet (V ³⁺ : YAG) and divalent cobalt-doped crystalline materials; and an optical cavity, the gain medium and The saturable absorber is located in the optical cavity, which includes a high reflectivity mirror and an output coupler. The passive Q-switched laser of claim 1, in addition to the gain medium and the saturable absorber, also includes undoped yttrium aluminum garnet for preventing heat accumulation in an absorption of the gain medium in the area. The passive Q-switched laser of claim 2, wherein the undoped yttrium aluminum garnet is shaped as a cylinder surrounding the gain medium and the saturable absorber. The passive Q-switched laser of claim 1, wherein at least one of the gain medium crystalline material and the saturable absorber crystalline material is polycrystalline. The passive Q-switched laser of claim 1, wherein both the gain medium crystal and the saturable absorber crystal material are polycrystalline. The passive Q-switched laser of claim 1, wherein the high reflectivity mirror and the output coupler are rigidly coupled to the gain medium and the saturable absorber such that the passive Q-switched laser is a single On-chip Microchip Passive Q-Switched Lasers. The passive Q-switched laser as claimed in claim 1, wherein the crystalline material of the gain medium is neodymium-doped yttrium orthovanadate (Nd: YVO ₄ ). The passive Q-switched laser as claimed in claim 1, wherein the saturable absorber crystalline material is cobalt-doped spinel (Co ²⁺ :MgAl ₂ O ₄ ). The passive Q-switched laser as claimed in claim 1, wherein the saturable absorber crystalline material is Co ²⁺ : YAG. The passive Q-switched laser as claimed in claim 1, wherein the saturable absorber crystalline material is cobalt-doped zinc selenide (Co ²⁺ : ZnSe). The passive Q-switched laser as claimed in claim 1, wherein the gain medium crystalline material is a ceramic cobalt-doped crystalline material. 2. The passive Q-switched laser of claim 1, wherein the gain medium and the saturable absorber are implemented on a monolithic crystalline material doped with neodymium and at least one other material. The passive Q-switched laser of claim 1, wherein the initial transmittance (T ₀ ) of the saturable absorber is between 78% and 82%. An electro-optic system comprising: the passive Q-switched laser of claim 1 configured to illuminate a target; and a sensor configured to sense radiation reflected from the illuminated target and Reflected lighting is converted into image data. The electro-optic system of claim 14, further comprising a processor operable to process the image data provided by the sensor to determine the presence of an object in a field of view of the electro-optic system. A method for manufacturing components of a passive Q-switch (P-QS) laser, the method comprising: packing at least one first powder into a first mold; compacting the powder in the first mold At least one first powder to produce a first green body. packing at least one second powder different from the at least one first powder into a second mold; compacting the at least one second powder in the second mold to produce a second green body; heating the first a green body to produce a first crystalline material; heating the second green body to produce a second crystalline material; and coupling the second crystalline material to the first crystalline material, wherein the first crystalline material and the One of the second crystalline materials is a neodymium doped crystalline material and is a gain medium for the passive Q-switched laser, wherein the other of the first crystalline material and the second crystalline material is used for the passive A saturable absorber (SA) of the Q-switched laser is also a material selected from the group consisting of a neodymium-doped crystalline material and a doped crystalline material selected from a A group consisting of trivalent vanadium-doped yttrium aluminum garnet (V ³⁺ : YAG) and a cobalt-doped crystalline material, and wherein at least one of the gain medium and the saturable absorber is a ceramic crystalline material. The method of claim 16, wherein the first mold is different from the second mold. The method of claim 16, wherein the first mold and the second mold are the same mold. The method of claim 16, wherein the heating of the first green body is performed prior to the compacting of the at least one second powder, wherein both the gain medium and the saturable absorber are polycrystalline materials. The method of claim 17, wherein the heating of the first green body is performed prior to the compaction of the at least one second powder, wherein the gain medium and the saturable absorber are polycrystalline materials. The method of claim 18, wherein the heating of the first green body is performed prior to the compacting of the at least one second powder, wherein both the gain medium and the saturable absorber are polycrystalline materials. The method of claim 16, wherein heating the first green body and heating the second green body comprises simultaneously heating the first green body and the second green body in a single oven, wherein the gain medium and the Saturable absorbers are all polycrystalline materials. The method of claim 17, wherein heating the first green body and heating the second green body comprises simultaneously heating the first green body and the second green body in a single oven, wherein the gain medium and the Saturable absorbers are all polycrystalline materials. The method of claim 18, wherein heating the first green body and heating the second green body comprises simultaneously heating the first green body and the second green body in a single oven, wherein the gain medium and the Saturable absorbers are all polycrystalline materials. The method of claim 16, wherein the coupling is a result of the heating of the single oven. The method of claim 17, wherein the coupling is a result of the heating of the single oven. The method of claim 18, wherein the coupling is a result of the heating of the single oven.

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