Optical detection and measurement devices

Abstract

To provide a light detection device capable of reducing optical crosstalk between light detection regions.SOLUTION: A light detection module 2 comprises a plurality of PD groups 221 and TIA arrays 23A and 23B. Each PD group 221 includes a PD 22a for detecting a light pulse made incident from outside the light detection module 2, and a PD 22b arranged side by side with the PD 22a. The TIA arrays 23A and 23B generate a signal corresponding to a difference between a current signal obtained by the PD 22a and a current signal obtained by the PD 22b. When a light pulse impinges on the PD 22a of one PD group 221 among the plurality of PD groups 221, part of the light pulse impinges on the PD 22a and PD 22b of at least one other PD group 221 through reflection and / or diffusion in the light detection module 2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to optical detection and measurement devices. [Background technology]

[0002] Patent Document 1 discloses a multi-channel optical detection and ranging system. The system includes a plurality of active channels. Each active channel includes a photosensitive element arranged to be exposed to light, and an analog front-end circuit that receives a signal from each photosensitive element. The system further includes at least one compensation channel and a processing unit. The compensation channel includes a compensation element that is substantially insensitive to light, and an analog front-end circuit that receives a signal from the compensation element. The processing unit receives signals from the active channels and the compensation channel, derives a compensation signal from the signal received from the compensation channel, and compensates for crosstalk interference of the active channels and / or interference common to the analog front-end circuit using the compensation signal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-119954 A Summary of the Invention [Problem to be solved by the invention]

[0004] An example of a device that detects the incident position and timing of an optical pulse in a plurality of optical detection regions (e.g., photodiodes) is LiDAR (Light Detection And Ranging). When a plurality of optical detection regions are arranged in such a device, the following problem occurs. When an optical pulse is incident on one optical detection region, a part of the optical pulse is also incident on other optical detection regions due to reflection, diffusion, or both inside the device. In this case, the optical pulse is erroneously recognized as having been incident on other optical detection regions at the same time as the optical pulse is incident on a certain optical detection region. In this specification, this phenomenon is referred to as optical crosstalk. For example, in LiDAR, such erroneous recognition leads to erroneous detection of an object that does not actually exist.

[0005] An object of the present disclosure is to provide a photodetection device capable of reducing optical crosstalk between photodetection regions, and a measurement device including the photodetection device. [Means for solving the problem]

[0006] A photodetection device according to an embodiment of the present disclosure includes a plurality of photodetection region groups and a circuit for generating a signal. Each of the plurality of photodetection region groups includes a first photodetection region for detecting a light pulse incident from outside the photodetection device, and a second photodetection region arranged side by side with the first photodetection region. The signal generating circuit is provided for each photodetection region group, and generates a signal corresponding to a difference between a first signal obtained by the first photodetection region and a second signal obtained by the second photodetection region. When a light pulse is incident on a first photodetection region of one of the plurality of photodetection region groups, a part of the light pulse is incident on the first photodetection region and the second photodetection region of at least one other photodetection region group due to reflection, diffusion, or both within the photodetection device.

[0007] A measurement device according to an embodiment of the present disclosure is a device that irradiates an optical pulse to an object to be measured, and measures a distance and a direction to the object to be measured based on an incident position of the optical pulse reflected on the object to be measured and a time difference between the irradiation of the optical pulse and the incidence of the reflected optical pulse. The optical detection device includes an optical emission unit that emits an optical pulse, and an optical detection unit that detects the optical pulse reflected on the object to be measured. The optical detection unit includes a plurality of optical detection region groups and a signal generation circuit. Each of the plurality of optical detection region groups includes a first optical detection region for detecting an optical pulse, and a second optical detection region arranged alongside the first optical detection region. The signal generation circuit is provided for each optical detection region group, and generates a signal corresponding to a difference between a first signal obtained by the first optical detection region and a second signal obtained by the second optical detection region. When a light pulse is incident on a first light detection region of one of the multiple light detection region groups, a portion of the light pulse is incident on the first light detection region and the second light detection region of at least one other light detection region group due to reflection, diffusion, or both within the measurement device. Effect of the Invention

[0008] According to the light detection device and measurement device disclosed herein, optical crosstalk between light detection regions can be reduced. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a measurement device according to an embodiment. [Diagram 2] FIG. 2 is a plan view of a photodetection module including a photodiode (PD) array and a transimpedance amplifier (TIA) array. [Diagram 3] FIG. 3 is a diagram showing a schematic cross-sectional structure of a PD array. [Figure 4] FIG. 4 is a circuit diagram showing a configuration of a photodetection circuit included in the photodetection module. [Diagram 5] FIG. 5 is a schematic diagram showing an embodiment in which an element for attenuating incident light is provided on the light receiving surface of a PD. [Figure 6]6(a) to (c) are diagrams illustrating optical crosstalk. [Figure 7] 7(a) and (b) are diagrams illustrating optical crosstalk. [Figure 8] FIG. 8 is a diagram for explaining the influence of optical crosstalk in a conventional LiDAR. [Figure 9] FIG. 9 is a plan view that shows a schematic diagram of a PD array fabricated for the experiment. [Figure 10] 10(a) and (b) are graphs showing the time waveforms of signals obtained from the PD array fabricated for the experiment. [Figure 11] 11(a) to 11(c) are diagrams for explaining the magnitude relationship between the light receiving sensitivities of two PDs constituting a PD group and their influence. [Figure 12] 12(a) and 12(b) are diagrams for explaining the magnitude relationship between the light receiving sensitivities of two PDs constituting a PD group and their influence. [Figure 13] FIG. 13 is a diagram showing a schematic diagram of an equivalent circuit of the PD array and its periphery. [Figure 14] FIG. 14 is a cross-sectional view showing the configuration of a light detection module according to a first modified example. [Figure 15] FIG. 15 is a circuit diagram showing a configuration of a photodetection circuit according to a second modified example. [Figure 16] FIG. 16 is a plan view illustrating a schematic configuration of a light detection module according to a third modified example. [Figure 17] FIG. 17 is a plan view illustrating a schematic configuration of a light detection module according to a fourth modified example. [Figure 18] FIG. 18 is a plan view illustrating a schematic configuration of a light detection module according to a fifth modified example. [Figure 19] FIG. 19 is a plan view diagrammatically illustrating a light detection module according to a sixth modified example. [Figure 20] FIG. 20 is a plan view illustrating a schematic configuration of a light detection module according to a seventh modified example. [Figure 21] FIG. 21 is a plan view diagrammatically illustrating a light detection module according to an eighth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A photodetection device according to an embodiment of the present disclosure includes a plurality of photodetection region groups and a signal generation circuit. Each of the plurality of photodetection region groups includes a first photodetection region for detecting a light pulse incident from outside the photodetection device, and a second photodetection region arranged alongside the first photodetection region. The signal generation circuit is provided for each photodetection region group, and generates a signal corresponding to a difference between a first signal obtained by the first photodetection region and a second signal obtained by the second photodetection region. When a light pulse is incident on a first photodetection region of one of the plurality of photodetection region groups, a part of the light pulse is incident on the first photodetection region and the second photodetection region of at least one other photodetection region group due to reflection, diffusion, or both within the photodetection device.

[0011] A measurement device according to an embodiment of the present disclosure is a device that irradiates an optical pulse to an object to be measured, and measures a distance and a direction to the object to be measured based on an incident position of the optical pulse reflected on the object to be measured and a time difference between the irradiation of the optical pulse and the incidence of the reflected optical pulse. The optical detection device includes an optical emission unit that emits an optical pulse, and an optical detection unit that detects the optical pulse reflected on the object to be measured. The optical detection unit includes a plurality of optical detection region groups and a signal generation circuit. Each of the plurality of optical detection region groups includes a first optical detection region for detecting an optical pulse, and a second optical detection region arranged alongside the first optical detection region. The signal generation circuit is provided for each optical detection region group, and generates a signal corresponding to a difference between a first signal obtained by the first optical detection region and a second signal obtained by the second optical detection region. When a light pulse is incident on a first light detection region of one of the multiple light detection region groups, a portion of the light pulse is incident on the first light detection region and the second light detection region of at least one other light detection region group due to reflection, diffusion, or both within the measurement device.

[0012] In these photodetection devices and measurement devices, when a part of the light pulse is incident on a photodetection region group other than the photodetection region group to which the first photodetection region to which the light pulse is incident belongs due to reflection, diffusion, or both within the photodetection device or measurement device, a first signal corresponding to the light intensity of the part is obtained by the first photodetection region, and at the same time, a second signal corresponding to the light intensity of the part is obtained by the second photodetection region. Since the first photodetection region and the second photodetection region are arranged side by side, there is no large difference between the intensity of the light incident on the first photodetection region and the intensity of the light incident on the second photodetection region. Then, a signal corresponding to the difference between these first and second signals is output from the signal generating circuit. That is, at least a part of the first signal generated in the first photodetection region due to optical crosstalk is offset by the second signal. Therefore, according to these photodetection devices and measurement devices, optical crosstalk between the first photodetection regions can be reduced. Therefore, it is possible to reduce erroneous detection of an object or shape that does not actually exist.

[0013] In these photodetection devices and measurement devices, even in the photodetection region group to which the first photodetection region to which the optical pulse is incident belongs, a part of the optical pulse enters the second photodetection region due to reflection, diffusion, or both. However, since the light entering the second photodetection region is weaker than the optical pulse entering the first photodetection region, a sufficiently large optical pulse detection signal can be output from the signal generation circuit corresponding to the photodetection region group.

[0014] The above-mentioned light detection device may further include a package that collectively houses the plurality of light detection region groups. When a light pulse is incident on the first light detection region of one of the plurality of light detection region groups, a part of the light pulse may be incident on the first light detection region and the second light detection region of at least one other light detection region group due to reflection, diffusion, or both inside the package. Depending on the structure of the package, optical crosstalk between the light detection regions may easily occur. The light detection device of the present disclosure is particularly effective when it includes such a package.

[0015] In the above photodetection device, the first photodetection regions may be arranged in one or two rows, and the second photodetection regions may be arranged in an area other than between the first photodetection regions. In this case, the first photodetection regions can be arranged at high density without the second photodetection regions interfering with the arrangement of the first photodetection regions.

[0016] The above photodetection device may further include a light blocking member that prevents a light pulse incident on the first photodetection region from directly entering the second photodetection region. In a photodetection region group in which a light pulse is incident on the first photodetection region, if a light pulse is also incident on the second photodetection region, the first signal, which is a light pulse detection signal, may be offset by the second signal in the signal generation circuit corresponding to that photodetection region group, making it impossible to recognize the light pulse detection signal. By including the light blocking member in the photodetection device, a light pulse is prevented from entering the second photodetection region, and the light pulse detection signal can be reliably recognized.

[0017] In each of the photodetection region groups, the light sensitivity of the second photodetection region at the wavelength of the optical pulse may be equal to the light sensitivity of the first photodetection region at the same wavelength. In this case, the difference between the first and second signals caused by optical crosstalk can be made close to zero. Therefore, according to this photodetection device, the optical crosstalk between the first photodetection regions can be effectively reduced.

[0018] In each of the photodetection region groups, the light sensitivity of the second photodetection region at the wavelength of the optical pulse may be smaller than the light sensitivity of the first photodetection region at the same wavelength. In this case, even if an optical pulse and crosstalk light due to another optical pulse are simultaneously incident on a certain photodetection region group, the optical pulse can be suitably detected.

[0019] In each of the photodetection region groups, the light receiving area of ​​the second photodetection region may be smaller than the light receiving area of ​​the first photodetection region. In this case, even if a light pulse and crosstalk light due to another light pulse are simultaneously incident on a certain photodetection region group, the light pulse can be suitably detected. However, in this case, the light receiving sensitivity of the second photodetection region may be equal to or smaller than the light receiving sensitivity of the first photodetection region.

[0020] In the above photodetection device, the first photodetection region and the second photodetection region may be avalanche photodiodes. In each photodetection region group, the avalanche multiplication factor in the second photodetection region may be smaller than the avalanche multiplication factor in the first photodetection region. In this case, even if a light pulse and crosstalk light due to another light pulse are simultaneously incident on a certain photodetection region group, the light pulse can be suitably detected.

[0021] In the above photodetection device, the second photodetection region of the group of photodetection regions may have an element that attenuates incident light on the light receiving surface. In this case, the same effect as when the light receiving sensitivity of the second photodetection region is made smaller than the light receiving sensitivity of the first photodetection region can be achieved. At least two of the following configurations may be combined: a configuration in which the light receiving area of ​​the second photodetection region is smaller than the light receiving area of ​​the first photodetection region; a configuration in which the avalanche multiplication factor of the second photodetection region is smaller than the avalanche multiplication factor of the first photodetection region; and a configuration in which an attenuation element is disposed on the light receiving surface of the second photodetection region.

[0022] In the above photodetection device, the bias supply path of the first photodetection region of the photodetection region group and the bias supply path of the second photodetection region of the photodetection region group may be common. In this case, when an optical pulse is incident on a certain first photodetection region and a current is output from the first photodetection region, the potential of the common bias fluctuates due to the impedance of the common bias supply path. As a result, a current is output from other first photodetection regions to which no optical pulse is incident. In this specification, this phenomenon is called common bias crosstalk. In this photodetection device, since the second photodetection region is also connected to the common bias supply path, a current output due to a fluctuation in the potential of the common bias also occurs in the second photodetection region. Therefore, at least a part of the first signal caused by the common bias crosstalk is offset by the second signal in the signal generation circuit. Therefore, the common bias crosstalk can be reduced.

[0023] In the above photodetector, the bias supply paths for the first and second photodetection regions may be electrically separated for each photodetection region group. In this case, the above-mentioned common bias crosstalk does not occur, and therefore it is possible to detect the optical pulse with higher accuracy.

[0024] Hereinafter, embodiments of a light detection device and a measurement device according to the present disclosure will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated descriptions will be omitted.

[0025] 1 is a diagram illustrating a schematic configuration of a measurement device 1 according to an embodiment of the present disclosure. The measurement device 1 irradiates a measurement object A with a light pulse PL1, which is a laser beam, and measures the distance and direction to the measurement object A based on the incident position of the light pulse PL2 reflected from the measurement object A and the time difference between the irradiation of the light pulse PL1 and the incidence of the light pulse PL2. As shown in FIG. 1, the measurement device 1 of this embodiment includes a light emitting unit 10 that emits the light pulse PL1, a light detecting unit 20 that detects the light pulse PL2, and a controller 8.

[0026] The light output unit 10 includes a driver 11, a pulsed laser 12, and a light emission optical system 13. The driver 11 is electrically connected to the controller 8, and periodically generates a pulsed driving current for the pulsed laser 12 based on an instruction signal from the controller 8. The driver 11 is configured by an electronic circuit including, for example, a transistor. The pulsed laser 12 is electrically connected to a current output terminal of the driver 11, and receives the driving current output from the driver 11. The pulsed laser 12 periodically outputs a light pulse PL1 including a light pulse according to the driving current. The wavelength of the light pulse PL1 is, for example, 300 nm or more and 1700 nm or less, and the half-width of the light pulse of the light pulse PL1 is, for example, 0.1 nsec or more and 100 nsec or less. The pulsed laser 12 is, for example, a laser diode. The light emission optical system 13 is optically coupled to the pulsed laser 12. The light emission optical system 13 scans the light pulse PL1 output from the pulsed laser 12, and irradiates the light pulse PL1 over a wide range.

[0027] The light detection unit 20 detects a light pulse PL2 from the measurement object A. The light detection unit 20 has a light receiving optical system 21, a photodiode (PD) array 22, a transimpedance amplifier (TIA) array 23, and an A / D converter array 24. The light receiving optical system 21 receives the light pulse PL2 and introduces the light pulse PL2 into one of N (N is an integer equal to or greater than 2; FIG. 1 illustrates a case where N=4) optical paths depending on the incident position of the light pulse PL2.

[0028] The PD array 22 includes N PDs 22a for detecting optical pulses included in the optical pulse PL2. Each PD 22a is a first optical detection region in this embodiment, and is, for example, a PN-type photodiode or an avalanche photodiode (APD). Each PD 22a is optically coupled to a corresponding optical path of the light receiving optical system 21. Each PD 22a generates a current signal according to the optical intensity of the optical pulse PL2 input from the corresponding optical path, and outputs this current signal from an output end. The N PDs 22a are arranged in one or two rows along a predetermined direction (for example, the scanning direction of the optical pulse PL1).

[0029] The TIA array 23 and the PD array 22 constitute a photodetection module (photodetection device) 2. The TIA array 23 includes N TIAs 23a. An input terminal of each TIA 23a is electrically connected to an output terminal of the corresponding PD 22a, and receives a current signal from the corresponding PD 22a. Each TIA 23a converts the current signal received from the corresponding PD 22a into a voltage signal, and outputs the voltage signal from an output terminal. The A / D converter array 24 includes N A / D converters 24a. An input terminal of each A / D converter 24a is electrically connected to an output terminal of the corresponding TIA 23a. Each A / D converter 24a converts the voltage signal received from the corresponding TIA 23a into a digital signal, and outputs the digital signal from an output terminal. Note that the number of A / D converters 24a may be less than the number N of TIAs 23a, with each A / D converter 24a receiving voltage signals sequentially from a plurality of TIAs 23a. Moreover, instead of the A / D converter 24a, a configuration in which a comparator and a time-to-digital (TD) converter are combined may be used.

[0030] The controller 8 is, for example, a computer including a CPU and a memory, and realizes various functions by the CPU reading and executing a program stored in the memory. The controller 8 is electrically connected to the driver 11 and provides an instruction signal to the driver 11. The controller 8 is also electrically connected to the output terminals of the N A / D converters 24a and receives the digital signal output from each A / D converter 24a. The controller 8 detects the incident position of the optical pulse PL2 in the light receiving optical system 21 based on which A / D converter 24a the controller 8 has received the digital signal from, and measures the direction in which the object A exists from this incident position. The controller 8 also calculates the distance from the measurement device 1 to the object A based on the time from when the controller 8 provides an instruction signal to the driver 11 to when the controller 8 receives the digital signal.

[0031] FIG. 2 is a plan view of the photodetection module 2 including the PD array 22 and the TIA array 23. As described above, the PD array 22 has N PDs 22a (FIG. 2 illustrates the case where N=8). In the illustrated example, the N PDs 22a are arranged in two rows. The PD array 22 further has N PDs 22b. Each PD 22a is a second photodetection region in this embodiment, and is, for example, a PN-type photodiode or an avalanche photodiode (APD). Each PD 22b corresponds to each PD 22a one-to-one, and is arranged in line with the corresponding PD 22a. The PD 22a and the corresponding PD 22b constitute a PD group 221. The PD group 221 is a photodetection region group in this embodiment. Each PD group 221 is made up of one PD 22a and one PD 22b. The PD array 22 has N PD groups 221. The N PD groups 221 are arranged in two rows. The N PDs 22b are arranged in regions other than the regions between the N PDs 22a, in other words, outside the array of the N PDs 22a. Therefore, the N PDs 22a are arranged adjacent to each other without any PDs 22b intervening between them.

[0032] The TIA array 23 in the illustrated example is divided into two chips (TIA array 23A and TIA array 23B). The TIA array 23A is arranged on one side of the PD array 22 in a direction intersecting with the arrangement direction of the PDs 22a, side by side with a gap therebetween. The TIA array 23B is arranged on the other side of the PD array 22 in the same direction, side by side with a gap therebetween. In other words, the TIA arrays 23A and 23B are arranged side by side in a direction intersecting with the arrangement direction of the PDs 22a, and the PD array 22 is arranged between the TIA array 23A and the TIA array 23B in the same direction.

[0033] The TIA array 23A and the output end of the PD22a in one row among the N PD22a are electrically connected via a wire 25a. The TIA array 23A and the output end of the PD22b corresponding to the PD22a in one row among the N PD22b are electrically connected via a wire 25b. The TIA array 23B and the output end of the PD22a in the other row among the N PD22a are electrically connected via a wire 25a. The TIA array 23B and the output end of the PD22b corresponding to the PD22a in the other row among the N PD22b are electrically connected via a wire 25b. The wires 25a and 25b are alternately arranged along the arrangement direction of the PD22a and extend along a direction intersecting the arrangement direction of the PD22a.

[0034] 3 is a diagram showing a cross-sectional structure of the PD array 22 when the PDs 22a and 22b are APDs. The N PDs 22a and the N PDs 22b are monolithically formed on a common substrate 220, which is a semiconductor substrate. Specifically, the PD array 22 has the common substrate 220, a first conductive type semiconductor layer 222 formed on the common substrate 220, (2×N) first conductive type semiconductor regions 223 formed in the semiconductor layer 222, (2×N) second conductive type semiconductor regions 224 formed in the semiconductor layer 222, an electrode 225, and (2×N) electrodes 226. Each semiconductor region 224 is disposed on each semiconductor region 223 and contacts each semiconductor region 223 to form a pn junction. In one example, the common substrate 220 is heavily p-type, the semiconductor layer 222 is lightly p-type, the semiconductor region 223 is heavily p-type, and the semiconductor region 224 is heavily n-type. Each pair of one semiconductor region 223 and one semiconductor region 224 constitutes a PD 22a or 22b. The electrode 225 is provided on the rear surface of the common substrate 220 and forms an ohmic junction with the rear surface of the common substrate 220. Each electrode 226 is provided on each semiconductor region 224 and forms an ohmic junction with each semiconductor region 224. When each semiconductor region 224 is n-type, each electrode 226 is a cathode electrode. When the common substrate 220 is p-type, the electrode 225 is an anode electrode.

[0035] In addition, when the PDs 22a and 22b are PN junction type PDs, the common substrate 220 may be an n-type. In that case, each electrode 226 serves as an anode electrode. Also, the electrode 225 serves as a cathode electrode.

[0036] Fig. 4 is a circuit diagram showing the configuration of a photodetection circuit included in the photodetection module 2. Fig. 4 shows only the connection between the TIA array 23A and the PD group 221 in one column of the PD array 22, but the connection between the TIA array 23B and the PD group 221 in the other column of the PD array 22 is similar.

[0037] The anodes of the N PDs 22a and the N PDs 22b are commonized by the common substrate 220 and the electrode 225 shown in FIG. 3 and are connected to the negative electrode of the bias power supply 41. The positive electrode of the bias power supply 41 is connected to a ground potential line (reference potential line). The bias power supply 41 supplies a negative bias voltage to the N PDs 22a and the N PDs 22b through a common bias supply path. The PD 22a generates a current signal Ja having a time waveform corresponding to the time waveform of the incident light. The PD 22b generates a current signal Jb having a time waveform corresponding to the time waveform of the incident light. However, if the common substrate 220 is n-type, for example, when the PDs 22a and 22b are PN junction type PDs, the cathodes of the N PDs 22a and the N PDs 22b are commonized by the common substrate 220 and the electrode 225 and are connected to the positive electrode of the bias power supply 41. In that case, the negative electrode of the bias power supply 41 is connected to the ground potential line (reference potential line). The bias power supply 41 supplies a positive bias voltage to the N PDs 22a and the N PDs 22b via a common bias supply path.

[0038] The TIA array 23A has the same number of TIAs 23a as the PD groups 221 in one column. The TIAs 23a are signal generating circuits in this embodiment, and are provided for each PD group 221. The TIAs 23a are differential input type TIAs. The positive phase input terminal of the TIA 23a is connected to the PD 22a via a wire 25a. The negative phase input terminal of the TIA 23a is connected to the PD 22b via a wire 25b. The TIA 23a generates an output signal Vout, which is a voltage signal according to (for example, proportional to) the difference between a current signal Ja received from the PD 22a via the wire 25a and a current signal Jb received from the PD 22b via the wire 25b. In this embodiment, the current signal Ja is a first signal obtained by the PD 22a, and the current signal Jb is a second signal obtained by the PD 22b.

[0039] The light receiving sensitivity of PD22b at the wavelengths of the optical pulses PL1 and PL2 may be equal to the light receiving sensitivity of PD22a at the wavelengths. Alternatively, the light receiving sensitivity of PD22b at the wavelengths of the optical pulses PL1 and PL2 may be smaller than the light receiving sensitivity of PD22a at the wavelengths. Also, the light receiving area of ​​PD22b may be smaller than the light receiving area of ​​PD22a. Alternatively, when PD22a and PD22b are APDs, in each PD group 221, the multiplication factor of avalanche multiplication in PD22b may be smaller than the multiplication factor of avalanche multiplication in PD22a. Alternatively, as shown in FIG. 5, in each PD group 221, only PD22b may have an element (e.g., an inorganic film or an organic film having optical attenuation) 227 that attenuates the incident light to each PD22b on the light receiving surface, and at least a part of the light receiving surface of each PD22b may be covered by this element 227.

[0040] When the optical pulse PL2 is incident on PD22a of one of the N PD groups 221, a part of the optical pulse PL2 is incident on PD22a and PD22b of at least one of the other PD groups 221 due to reflection, diffusion, or both within the measurement device 1. Figures 6(a) to (c) and Figures 7(a) and (b) are diagrams for explaining such a phenomenon.

[0041] FIG. 6(a) is a cross-sectional view showing a case where the light detection module 2 includes a package 60A. The package 60A accommodates N PD groups 221 together. In one example, the package 60A accommodates the PD array 22 in which N PD groups 221 are monolithically integrated. The package 60A has a bottomed container 61 with an open top and a light-transmitting material 62 filling the inside of the bottomed container 61. The PD array 22 is mounted on the bottom surface of the bottomed container 61, and at least the light-receiving surface of the PD array 22 is covered with the light-transmitting material 62. In the illustrated example, the light-transmitting material 62 is in contact with the light-receiving surface of the PD array 22. The material of the bottomed container 61 is, for example, a printed writing board (PWB). The light-transmitting material 62 has light transmittance at the wavelength of the light pulse PL2. In this embodiment, having light transmittance means, for example, that the light transmittance is 50% or more and 100% or less. The light-transmitting material 62 mainly includes, for example, a resin.

[0042] When the light pulse PL2 enters the package 60A, the light pulse PL2 passes through the light-transmitting material 62 and enters the PD22a of one of the N PD groups 221. Furthermore, a portion of the light pulse PL2 that entered the package 60A does not enter the PD22a but becomes crosstalk light SL due to reflection, diffusion, or both at the interface between the light-transmitting material 62 and air, the interface between the light-transmitting material 62 and the PD array 22, or inside the light-transmitting material 62, and enters the PD22a and PD22b of at least another PD group 221 directly or by being reflected at the interface between the light-transmitting material 62 and air.

[0043] FIG. 6(b) is a cross-sectional view showing a case where the light detection module 2 includes a package 60B. The package 60B accommodates N PD groups 221 together. In one example, the package 60B accommodates the PD array 22 in which N PD groups 221 are monolithically integrated. The package 60B includes a bottomed container 61 similar to that shown in FIG. 6(a) and a top plate 63 that closes the top opening of the bottomed container 61. The PD array 22 is mounted on the bottom surface of the bottomed container 61, and an accommodation space 64 defined by the bottomed container 61 and the top plate 63 is filled with air except for the area occupied by the PD array 22. The top plate 63 airtightly seals the top opening of the bottomed container 61. The top plate 63 is optically transparent at the wavelength of the optical pulse PL2. Note that only a part of the top plate 63, including an area through which the optical pulse PL2 passes, may be optically transparent, and the other areas may be light-shielding. In this embodiment, having a light blocking property means, for example, that the light transmittance is equal to or greater than 0% and less than 50%. The top plate 63 is, for example, a glass plate.

[0044] When the light pulse PL2 enters this package 60B, the light pulse PL2 passes through the top plate 63 and enters the PD22a of one of the N PD groups 221. A part of the light pulse PL2 that entered the package 60B does not enter the PD22a but becomes crosstalk light SL due to reflection, diffusion, or both at the interface between the top plate 63 and the accommodation space 64, the light receiving surface of the PD array 22, or the periphery thereof, and enters the PD22a and PD22b of at least another PD group 221 by being reflected at the back surface of the top plate 63 or the inner wall of the accommodation space 64, or directly.

[0045] FIG. 6(c) is a cross-sectional view showing a case where the light detection module 2 includes a package 60C. The package 60C accommodates N PD groups 221 together. In one example, the package 60C accommodates the PD array 22 in which N PD groups 221 are monolithically integrated. The package 60C includes a flat light-transmitting material 65 in addition to the configuration of the package 60A described above. The light-transmitting material 65 is disposed on the PD array 22 and is covered by the light-transmitting material 62. That is, the light-transmitting material 65 is interposed between the PD array 22 and the light-transmitting material 62. In the illustrated example, the light-transmitting material 62 is in contact with one surface of the light-transmitting material 65, and the light receiving surface of the PD array 22 is in contact with the other surface of the light-transmitting material 65. The light-transmitting material 65 has optical transparency at the wavelength of the optical pulse PL2. The material of the light-transmitting material 65 is different from the material of the light-transmitting material 62. The material of the light-transmitting material 65 is, for example, glass.

[0046] When the light pulse PL2 enters the package 60C, the light pulse PL2 passes through the light-transmitting materials 62 and 65 and enters the PD22a of one of the N PD groups 221. A part of the light pulse PL2 that entered the package 60C does not enter the PD22a but becomes crosstalk light SL due to reflection, diffusion, or both at the interface between the light-transmitting material 62 and air, the interface between the light-transmitting material 62 and the light-transmitting material 65, the interface between the light-transmitting material 65 and the PD array 22, or inside the light-transmitting materials 62 and 65, and enters the PD22a and PD22b of at least another PD group 221 directly or by being reflected at the interface between the light-transmitting material 62 and air or the interface between the light-transmitting material 62 and the light-transmitting material 65.

[0047] In addition, in the package 60C, the light transmitting material 62 may be omitted. In that case, the crosstalk light SL is incident on the PD 22a and the PD 22b of at least another PD group 221 due to a phenomenon similar to that in the package 60A.

[0048] Fig. 7(a) is a cross-sectional view showing an embodiment in which N PD groups 221 are formed on separate individual PD chips instead of the PD array 22 in the embodiment shown in Fig. 6(a). Even in this case, crosstalk light SL is incident on PD22a and PD22b of at least another PD group 221, as in the embodiment shown in Fig. 6(a).

[0049] 7(b) shows a configuration in which an optical component 66 is disposed opposite the PD array 22. The optical component 66 is, for example, a focusing lens for focusing the optical pulse PL2 on one PD22a. In such a configuration, a part of the incident optical pulse PL2 becomes crosstalk light SL without entering the PD22a due to reflection, diffusion, or both at the interface between the optical component 66 and air, the light receiving surface of the PD array 22, or the periphery thereof, and is then reflected at the interface between the optical component 66 and air or the like, or is directly incident on PD22a and PD22b of at least another PD group 221.

[0050] The crosstalk light SL is also reflected and scattered by other components such as the housing of the measurement device 1, and is incident on the PD 22a and PD 22b of at least another PD group 221.

[0051] Furthermore, when the light pulse PL2 is incident on PD22a of one of the PD groups 221 and the crosstalk light SL is incident on PD22a and PD22b of at least another of the PD groups 221, it does not matter whether the crosstalk light SL is incident before or after the light pulse PL2. That is, the crosstalk light SL and the light pulse PL2 may be incident at the same time, or the crosstalk light SL may be incident before or after the light pulse PL2.

[0052] The effects obtained by the light detection module 2 and the measurement device 1 of the present embodiment having the above configuration will be described. FIG. 8 is a diagram for explaining the influence of optical crosstalk in a conventional LiDAR. In a conventional LiDAR, when a light pulse PL1 is irradiated from the light emitting unit 101, the light pulse PL1 is reflected by the measurement object A and enters one PD as a light pulse PL2. Then, a current signal corresponding to the light pulse PL2 is generated in the PD, and this current signal is converted into a voltage signal in the TIA. As a result, a voltage pulse P1 having a time waveform corresponding to the time waveform of the light pulse PL2 is output from the TIA. This voltage pulse P1 is converted into a digital signal by an A / D converter provided after the TIA, and the measurement object A is recognized in the area corresponding to the PD based on a pulse detection algorithm.

[0053] Meanwhile, the crosstalk light SL generated by the optical crosstalk is incident on the other PDs except the PD on which the optical pulse PL2 is incident. Then, current signals corresponding to the crosstalk light SL are generated in these PDs, and these current signals are converted into voltage signals in the TIAs connected to these PDs. As a result, voltage pulses P2 having a time waveform corresponding to the time waveform of the crosstalk light SL are output from these TIAs. These voltage pulses P2 are converted into digital signals by an AD converter provided after the TIA. Therefore, based on the pulse detection algorithm, an object Af or shape that does not actually exist is erroneously detected in the area corresponding to these PDs.

[0054] The light detection module 2 and the measurement device 1 of this embodiment solve this problem. That is, when a part of the light pulse PL2, i.e., the crosstalk light SL, is incident on the other PD group 221 except the PD group 221 to which the PD22a to which the light pulse PL2 is incident belongs due to reflection, diffusion, or both inside the measurement device 1 (particularly inside the packages 60A to 60D), a current signal Ja corresponding to the light intensity of the crosstalk light SL is obtained by the PD22a, and at the same time, a current signal Jb corresponding to the light intensity of the crosstalk light SL is obtained by the PD22b. Since the PD22a and the PD22b are arranged side by side, there is no large difference between the intensity of the crosstalk light SL incident on the PD22a and the intensity of the crosstalk light SL incident on the PD22b. Then, an output signal Vout corresponding to (for example, proportional to) the difference between these current signals Ja and Jb is output from the TIA 23a. That is, at least a part of the current signal Ja generated in the PD22a due to the optical crosstalk is offset by the current signal Jb. Therefore, according to the light detection module 2 and the measurement device 1 of this embodiment, it is possible to reduce optical crosstalk between the PDs 22a, and therefore it is possible to reduce erroneous detection of an object Af or shape that does not actually exist.

[0055] In addition, in the PD group 221 to which the PD22a to which the optical pulse PL2 is incident belongs, crosstalk light SL, which is a part of the optical pulse PL2, is incident on the PD22b due to reflection, diffusion, or both. However, since the crosstalk light SL incident on the PD22b is weaker than the optical pulse PL2 incident on the PD22a, an output signal Vout (optical pulse detection signal) having a sufficient magnitude can be output from the TIA 23a corresponding to the PD group 221. Therefore, the measurement object A can be appropriately detected.

[0056] Here, the inventors conducted an experiment to confirm the effects of the light detection module 2 and the measurement device 1 of this embodiment. FIG. 9 is a plan view that shows a schematic diagram of a PD array 70 fabricated for the experiment. This PD array 70 has four PDs 72a to 72d arranged in two rows and two columns. An optical pulse was made incident on one of the PDs, 72a, and crosstalk light was made incident on the other PDs 72b to 72d, and the current signals from each of the PDs 72a to 72d were converted into voltage signals and measured. In FIG. 9, the light intensity distribution is shown by shading of color, and the darker the area, the greater the light intensity.

[0057] FIG. 10(a) is a graph obtained by converting a current signal from PD72a into a voltage signal. Graph G1 in FIG. 10(b) is a graph obtained by converting a current signal from PD72c adjacent to PD72a in the row direction into a voltage signal. Graph G2 in FIG. 10(b) is a graph showing the result of calculating the difference between a voltage signal converted from the current signal of PD72c and a voltage signal converted from the current signal of PD72d adjacent to PD72c in the column direction. Referring to FIG. 10(b), the difference (graph G2) between the voltage signal converted from the current signal of PD72c and the voltage signal converted from the current signal of PD72d is significantly smaller than the voltage signal converted from the current signal of PD72c (graph G1). This suggests that the output signal Vout from the PD group 221 receiving the crosstalk light SL of this embodiment is significantly smaller than the voltage pulse P2 due to the optical crosstalk shown in FIG. 8. That is, according to the light detection module 2 and the measurement device 1 of this embodiment, the optical crosstalk between the PDs 22a can be effectively reduced.

[0058] As shown in Figs. 6 and 7, the light detection module 2 may further include a package 60A, 60B, or 60C that collectively houses a plurality of PD groups 221. When the light pulse PL2 is incident on the PD22a of one of the plurality of PD groups 221, a part of the light pulse PL2 (crosstalk light SL) may be incident on the PD22a and PD22b of at least one other PD group 221 due to reflection, diffusion, or both inside the package 60A, 60B, or 60C. Depending on the structure of the package, optical crosstalk between the PD22a may easily occur. The light detection module 2 and the measurement device 1 of this embodiment are particularly effective when the package 60A, 60B, or 60C is included.

[0059] 2, the multiple PDs 22a may be arranged in two rows, and the multiple PDs 22b may be arranged in an area other than between the multiple PDs 22a. In this case, the multiple PDs 22a can be arranged at high density without the PDs 22b interfering with the arrangement of the multiple PDs 22a.

[0060] As described above, in each PD group 221, the light receiving sensitivity of PD22b at the wavelength of the optical pulse PL2 may be equal to the light receiving sensitivity of PD22a at the same wavelength. Alternatively, in each PD group 221, the light receiving sensitivity of PD22b at the wavelength of the optical pulse PL2 may be lower than the light receiving sensitivity of PD22a at the same wavelength. Below, the magnitude relationship between the light receiving sensitivities of PD22a and 22b and their influence will be considered.

[0061] 11(a) shows a case where the light receiving sensitivities of the PDs 22a and 22b are substantially equal to each other. In this case, the height of the pulse Pa included in the current signal Ja of the PD 22a caused by the incidence of the crosstalk light SL and the height of the pulse Pb included in the current signal Jb of the PD 22b caused by the incidence of the crosstalk light SL are substantially equal to each other. Therefore, the height of the pulse Pc included in the output signal Vout of the TIA 23a becomes close to zero, so that the optical crosstalk can be reduced most effectively.

[0062] 11(b) shows a case where the light receiving sensitivity of PD22b is lower than that of PD22a. In this case, the height of the pulse Pb included in the current signal Jb of PD22b caused by the incidence of the crosstalk light SL is lower than the height of the pulse Pa included in the current signal Ja of PD22a caused by the incidence of the crosstalk light SL. Therefore, the height of the pulse Pc included in the output signal Vout of the TIA 23a is larger than that in the case of FIG. 11(a). However, even in this case, the optical crosstalk can be reduced compared to the conventional photodetector.

[0063] Fig. 11(c) shows a case where the light receiving sensitivity of PD22b is greater than that of PD22a. In this case, the height of the pulse Pb included in the current signal Jb of PD22b caused by the incidence of the crosstalk light SL is greater than the height of the pulse Pa included in the current signal Ja of PD22a caused by the incidence of the crosstalk light SL. Therefore, the pulse Pc included in the output signal Vout of the TIA 23a has a negative peak, and its height is greater than that in the case of Fig. 11(a). However, even in this case, the optical crosstalk can be reduced compared to the conventional photodetector.

[0064] Here, FIG. 12(a) is a diagram for explaining the time waveform of the output signal Vout when the crosstalk light SL and the optical pulse PL2 are simultaneously incident on a certain PD group 221 when the light receiving sensitivity of the PD22b is equal to that of the PD22a. As described above, in this case, the height of the pulse Pb included in the current signal Jb of the PD22b caused by the incidence of the crosstalk light SL is almost equal to the height of the pulse Pa included in the current signal Ja1 of the PD22a caused by the incidence of the crosstalk light SL. Therefore, the component Vout2 caused by the crosstalk light SL in the time waveform of the output signal Vout is almost flat. On the other hand, the current signal Ja2 caused in the PD22a by the incidence of the optical pulse PL2 includes a pulse Pd having a time waveform corresponding to the time waveform of the optical pulse PL2. Therefore, the component Vout1 caused by the optical pulse PL2 in the time waveform of the output signal Vout includes a pulse Pd having a time waveform corresponding to the time waveform of the optical pulse PL2. As a result, the output signal Vout includes a pulse Pd having a time waveform corresponding to the time waveform of the optical pulse PL2, so that the optical pulse PL2 can be suitably detected.

[0065] 12(b) is a diagram for explaining the time waveform of the output signal Vout when the crosstalk light SL and the optical pulse PL2 are simultaneously incident on a certain PD group 221 in the case where the light receiving sensitivity of the PD22b is higher than that of the PD22a. As described above, in this case, the height of the pulse Pb included in the current signal Jb of the PD22b caused by the incidence of the crosstalk light SL is higher than the height of the pulse Pa included in the current signal Ja1 of the PD22a caused by the incidence of the crosstalk light SL. Therefore, the component Vout2 caused by the crosstalk light SL in the time waveform of the output signal Vout includes a negative pulse Pc corresponding to the difference between the pulse Pa and the pulse Pb. On the other hand, the current signal Ja2 generated in the PD22a by the incidence of the optical pulse PL2 includes a pulse Pd having a time waveform corresponding to the time waveform of the optical pulse PL2. Therefore, the component Vout1 caused by the optical pulse PL2 in the time waveform of the output signal Vout includes a pulse Pd having a time waveform corresponding to the time waveform of the optical pulse PL2. As a result, the pulse Pd is cancelled out or reduced by the pulse Pc in the output signal Vout, so that the light pulse PL2 may not be detected.

[0066] For the above reasons, it is preferable that the light receiving sensitivity of PD22b is equal to that of PD22a. Or, even if the light receiving sensitivity of PD22b is smaller than that of PD22a, the pulse Pc of the component Vout2 caused by the crosstalk light SL has a positive peak, so that the pulse Pd is not offset or reduced by the pulse Pc. Therefore, the light receiving sensitivity of PD22b may be smaller than that of PD22a.

[0067] As described above, in each PD group 221, the light receiving area of ​​PD22b may be smaller than the light receiving area of ​​PD22a. For example, with such a configuration, similar to the case where the light receiving sensitivity of PD22b is smaller than the light receiving sensitivity of PD22a, even if the crosstalk light SL and the light pulse PL2 are simultaneously incident on a certain PD group 221, the light pulse PL2 can be suitably detected. However, in a configuration in which the light receiving area of ​​PD22b is smaller than the light receiving area of ​​PD22a, the light receiving sensitivity of PD22b may be equal to the light receiving sensitivity of PD22a or may be smaller than the light receiving sensitivity of PD22a. Also, when PD22a and PD22b are avalanche photodiodes, in each PD group 221, the multiplication factor of the avalanche multiplication of PD22b may be smaller than the multiplication factor of the avalanche multiplication of PD22a. In this case as well, even if the crosstalk light SL and the light pulse PL2 are simultaneously incident on a certain PD group 221, the light pulse PL2 can be suitably detected.

[0068] As described above, in each PD group 221, PD22b may have an element 227 that attenuates incident light on its light receiving surface. In this case, too, it is possible to achieve the same effect as when the light receiving sensitivity of PD22b is made smaller than that of PD22a. At least two of the above-mentioned configurations may be combined: a configuration in which the light receiving area of ​​PD22b is smaller than that of PD22a; a configuration in which the multiplication factor of avalanche multiplication in PD22b is smaller than that of PD22a; and a configuration in which the element 227 that attenuates incident light is provided on the light receiving surface of PD22b.

[0069] As in the present embodiment, the bias supply path of the N PDs 22a and the bias supply path of the N PDs 22b may be common. FIG. 13 is a diagram showing, as an example, the PD array 22 and an equivalent circuit around it in the case where the PDs 22a and 22b are APDs and the bias supply path is connected to the anode. In the figure, the PD 22a to which the optical pulse PL2 is incident is equivalently represented by a current source 51 and a capacitance C1 connected in parallel to each other. The PDs 22a and 22b belonging to the other PD group 221 are equivalently represented by a capacitance C1. The bias supply path 40 has wiring represented by two impedances R1 and R2 connected in series between the anodes of the N PDs 22a and the N PDs 22b and the bias power supply 41. A node N1 between the impedance R1 and the impedance R2 is connected to a bypass capacitor C2 via a wiring represented by an inductance L1.

[0070] In such an equivalent circuit, when an optical pulse PL2 is incident on a certain PD 22a and a current signal Ja is generated in the PD 22a, the potential (common bias) of the anodes of the PDs 22a and 22b fluctuates due to the impedances R1 and R2 of the bias supply path 40. As a result, the current signal Ja is output from the other PDs 22a to which the optical pulse PL2 is not incident (common bias crosstalk). In this embodiment, the anode of the PD 22b is also connected to the bias supply path 40, so that a current signal Jb caused by the fluctuating anode potential is also generated in the PD 22b. Therefore, at least a part of the current signal Ja caused by the common bias crosstalk is offset by the current signal Jb in the TIA 23a. Therefore, according to this embodiment, the common bias crosstalk can be reduced. This effect can also be obtained when the bias supply path 40 is connected to the cathodes of the PDs 22a and 22b (i.e., a common bias is supplied to the cathodes).

[0071] (First Modification) FIG. 14 is a cross-sectional view showing a configuration of a light detection module 2A according to a first modification. In addition to the above configuration, this light detection module 2A further includes a light blocking member 67. The light blocking member 67 prevents the light pulse PL2 incident on the PD 22a from directly incident on the PD 22b. In the illustrated example, the light blocking member 67 has a flat plate-shaped member 67a. The member 67a has light blocking properties at least at the wavelength of the light pulse PL2. The material of the member 67a is, for example, metal. In the member 67a, an optical window 67b for passing the light pulse PL2 is provided in an area facing the PD 22a. The optical window 67b may be an opening, or may be made of a member such as transparent glass having optical transparency at least at the wavelength of the light pulse PL2.

[0072] In PD group 221 in which optical pulse PL2 is incident on PD 22a, if optical pulse PL2 is also incident on PD 22b, there is a risk that the current signal Ja, which is an optical pulse detection signal, will be offset or excessively reduced by the current signal Jb in TIA 23a corresponding to that PD group 221, making it impossible to detect optical pulse PL2. By providing light detection module 2A with light blocking member 67 as in this modification, optical pulse PL2 can be prevented from being directly incident on PD 22b, and optical pulse PL2 can be reliably detected.

[0073] In this modification, the light shielding member 67 is disposed away from the light receiving surface of the PD 22b and is not disposed directly on (i.e., in contact with) the light receiving surface of the PD 22b. Therefore, the optical pulse PL2 is not directly incident on the PD 22b, but the crosstalk light SL is incident on the PD 22b without being blocked by the light shielding member 67.

[0074] (Second Modification) Fig. 15 is a circuit diagram showing the configuration of a photodetection circuit according to a second modified example. The photodetection module of this modified example has a TIA array 23C instead of the TIA array 23A shown in Fig. 4. The TIA array 23B (see Fig. 2) also has a similar configuration to the TIA array 23C. The configuration other than the TIA array is the same as that of the above-mentioned embodiment.

[0075] The TIA array 23C has N signal generating circuits 23b that correspond one-to-one to the PD group 221. Each signal generating circuit 23b includes single-ended input type TIAs 231 and 232 and a differential amplifier circuit 233. The TIA 231 is connected to the PD 22a via a wire 25a, and converts a current signal Ja received from the PD 22a into a voltage signal. The output terminal of the TIA 231 is connected to a positive phase input terminal of the differential amplifier circuit 233. The TIA 232 is connected to the PD 22b via a wire 25b, and converts a current signal Jb received from the PD 22b into a voltage signal. The output terminal of the TIA 232 is connected to a negative phase input terminal of the differential amplifier circuit 233. The differential amplifier circuit 233 generates an output signal Vout according to (for example, proportional to) the difference between the voltage signal output from the TIA 231 and the voltage signal output from the TIA 232. The differential amplifier circuit 233 may be formed on a common chip together with the TIAs 231 and 232, or may be formed on a chip separate from the TIAs 231 and 232. According to the configuration of this modification, it is possible to achieve the same effects as the configuration of the above-described embodiment (FIG. 4).

[0076] (Third to eighth modified examples) 16 to 21 are plan views each showing a schematic view of light detection modules 2C to 2H according to a third to eighth modified examples.

[0077] A light detection module 2C of a third modified example shown in FIG. 16 has a PD array 22A instead of the above-mentioned PD array 22. The PD array 22A differs from the above-mentioned PD array 22 (see FIG. 2) in that the PD groups 221 are arranged in only one row. The TIA array 23 is divided into two chips (TIA array 23D and TIA array 23E). The TIA array 23D is arranged on one side of the PD array 22A in a direction intersecting the arrangement direction of the PD groups 221 (i.e., the arrangement direction of the PDs 22a) and is arranged next to the PD array 22A at a distance. The TIA array 23E is arranged on the other side of the PD array 22A in the same direction and is arranged next to the PD array 22A at a distance.

[0078] In the arrangement of N PD groups 221, the PD groups 221 connected to the TIA array 23D and the PD groups 221 connected to the TIA array 23E are alternately arranged. The PDs 22a and 22b of the PD group 221 connected to the TIA array 23D are connected to the TIA array 23D via wires 25a and 25b, respectively. Similarly, the PDs 22a and 22b of the PD group 221 connected to the TIA array 23E are connected to the TIA array 23E via wires 25a and 25b, respectively. The TIA arrays 23D and 23E have TIAs 23a (or signal generating circuits 23b shown in FIG. 15) that correspond one-to-one to the PD groups 221 connected to them.

[0079] A light detection module 2D of a fourth modified example shown in FIG. 17 has a PD array 22A instead of the above-mentioned PD array 22. The PD array 22A is different from the above-mentioned PD array 22 (see FIG. 2) in that the PD groups 221 are arranged in only one row. The light detection module 2D also has N TIA chips 23F instead of the TIA array 23. Each TIA chip 23F corresponds to a PD group 221 one-to-one and incorporates a single TIA 23a. The N TIA chips 23F are aligned along the arrangement direction of the PD group 221 (i.e., the arrangement direction of the PDs 22a) and are arranged on one side of the PD array 22A in a direction intersecting the arrangement direction with a gap between them. The PDs 22a and 22b of each PD group 221 are connected to the corresponding TIA chips 23F via wires 25a and 25b, respectively.

[0080] A light detection module 2E of a fifth modified example shown in FIG. 18 has PD arrays 22B and 22C instead of the above-mentioned PD array 22. The PD array 22B has PDs 22a arranged in a row. The PD array 22C has PDs 22b arranged in a row. Thus, in the fifth modified example, the PDs 22a and PDs 22b are formed in separate PD arrays. The arrangement direction of the PDs 22a is aligned with the arrangement direction of the PDs 22b. The PD array 22C is arranged next to the PD array 22B in a direction intersecting the arrangement direction so that each PD 22b is aligned with the corresponding PD 22a (which together constitute the PD group 221). The TIA array 23A is arranged next to the PD arrays 22B and 22C in a direction intersecting the arrangement direction. In the illustrated example, the TIA array 23A is arranged on the PD array 22C side, but the TIA array 23A may be arranged on the PD array 22B side. Each PD 22a of the PD array 22B is connected to the TIA array 23A via a wire 25a. Each PD 22b of the PD array 22C is connected to the TIA array 23A via a wire 25b.

[0081] A light detection module 2F of a sixth modified example shown in FIG. 19 has a PD array 22D instead of the above-mentioned PD array 22. The PD array 22D differs from the above-mentioned PD array 22 (see FIG. 2) in that the PD group 221 is arranged in only one row. The PD array 22D also differs from the above-mentioned PD array 22A (see FIG. 16) in that N PDs 22a are arranged in one row along a certain direction, and among the N PDs 22b, the PDs 22b connected to the TIA array 23D are arranged on the TIA array 23D side with respect to the PDs 22a, and among the N PDs 22b, the PDs 22b connected to the TIA array 23E are arranged on the TIA array 23E side with respect to the PDs 22a. The other configurations of the light detection module 2F are similar to those of the light detection module 2C shown in FIG. 16.

[0082] The light detection module 2G of the seventh modification shown in FIG. 20 has N PD arrays 22E instead of the above-mentioned PD array 22. Each PD array 22E has one PD group 221. The N PD arrays 22E are arranged in a line along a certain direction, and the PD22a and PD22b of each PD array 22E are arranged in a direction intersecting the arrangement direction of the N PD arrays 22E. The light detection module 2G also has N TIA chips 23F instead of the TIA array 23. The N TIA chips 23F are arranged in the arrangement direction of the N PD arrays 22E (i.e., the arrangement direction of the PD22a). Each TIA chip 23F corresponds to the PD array 22E one-to-one, and includes a single TIA 23a (or a signal generating circuit 23b shown in FIG. 15). Each TIA chip 23F is arranged in a line with the corresponding PD array 22E in a direction intersecting the arrangement direction of the N PD arrays 22E. The PDs 22a and 22b of each PD array 22E are connected to the corresponding TIA chip 23F via wires 25a and 25b, respectively.

[0083] The light detection module 2H of the eighth modification shown in FIG. 21 has N PD chips 22F and N PD chips 22G instead of the above-mentioned PD array 22. Each PD chip 22F incorporates one PD 22a. Each PD chip 22G incorporates one PD 22b. In other words, in the light detection module 2H of the eighth modification, the N PD 22a and the N PD 22b are each composed of a separate PD chip. The N PD chips 22F are arranged side by side along a certain direction. The N PD chips 22G are arranged side by side along the arrangement direction of the N PD chips 22F. Each PD chip 22G is arranged side by side with the corresponding PD chip 22F (which together constitute the PD group 221) in a direction intersecting the arrangement direction. The light detection module 2H also has N TIA chips 23F instead of the TIA array 23. The N TIA chips 23F are arranged in the arrangement direction of the N PD chips 22F (i.e., the arrangement direction of the PD22a). Each TIA chip 23F corresponds to a pair of the PD chips 22F and 22G on a one-to-one basis, and includes a single TIA 23a (or a signal generating circuit 23b shown in FIG. 15). Each TIA chip 23F is arranged in a direction intersecting the arrangement direction of the N PD chips 22F with respect to the corresponding pair of the PD chips 22F and 22G. The PD22a of each PD chip 22F is connected to the corresponding TIA chip 23F via a wire 25a. The PD22b of each PD chip 22G is connected to the corresponding TIA chip 23F via a wire 25b.

[0084] The configurations of the light detection modules 2C to 2H according to the third to eighth modified examples described above can also achieve the same effects as those of the above-described embodiment.

[0085] In the photodetection module 2G of the seventh modified example shown in Fig. 20 and the photodetection module 2H of the eighth modified example shown in Fig. 21, the bias supply paths 40 (see Fig. 13) of the N PDs 22a and the N PDs 22b can be electrically separated for each PD group 221. In that case, the above-mentioned common bias crosstalk does not occur, and therefore the optical pulse PL2 can be detected with higher accuracy.

[0086] The photodetector and the measurement device according to the present disclosure are not limited to the above-mentioned embodiment, and various other modifications are possible. For example, in the above-mentioned embodiment and modification, a combination of a differential input type TIA or a single-ended input type TIA and a differential amplifier circuit is exemplified as the signal generating circuit. However, as the signal generating circuit, various other configurations can be adopted as long as it can generate an output signal corresponding to the difference between the first signal and the second signal. For example, the voltage signal obtained from the single-ended input type TIA may be A / D converted and digitized, and then the difference may be calculated in the controller 8 or another digital device.

[0087] Furthermore, in the above embodiment and modified examples, PD and APD are exemplified as the first and second photodetection regions, but other photodetection elements such as photomultiplier tubes may also be used in addition to PD and APD. [Explanation of symbols]

[0088] 1...measuring device, 2, 2A, 2C to 2H...light detection module, 10...light emitting section, 20...light detection section, 8...controller, 11...driver, 12...pulse laser, 13...light emitting optical system, 21...light receiving optical system, 22, 22A to 22E...PD array, 22F, 22G...PD chip, 22a, 22b...PD, 220...common substrate, 221...PD group, 222...semiconductor layer, 223, 224...semiconductor region, 225, 226...electrode, 227...element, 23, 23A to 23F...TIA array, 23a...TIA, 23b...signal generating circuit, 231, 232...TIA, 233...differential amplifier circuit, 24...A / D converter array, 24a...A / D converter, 25a, 25b...wire ya, 40...bias supply path, 41...bias power supply, 51...current source, 60A, 60B, 60C, 60D...package, 61...bottomed container, 62, 65...light-transmitting material, 63...top plate, 64...accommodation space, 66...optical component, 67...light-shielding member, 67a...member, 67b...optical window, 70...PD array, 101...light emitting portion, A...measurement object, Af...object, C1...capacitance, C2...bypass capacitor, Ja, Jb, Ja1, Ja2...current signal, L1...inductance, N1...node, PL1, PL2...light pulse, P1, P2...voltage pulse, Pa, Pb, Pc, Pd...pulse, R1, R2...impedance, SL...crosstalk light, Vout...output signal.

Claims

1. a plurality of photodetection region groups each including a first photodetection region for detecting a light pulse incident from outside the photodetection device and a second photodetection region arranged alongside the first photodetection region; a signal generating circuit provided for each of the photodetection region groups, the signal generating circuit generating a signal corresponding to a difference between a first signal obtained by the first photodetection region and a second signal obtained by the second photodetection region; Equipped with a light detection device, wherein when the light pulse is incident on the first light detection region of one of the plurality of light detection region groups, a part of the light pulse is incident on the first light detection region and the second light detection region of at least one other of the light detection region groups due to reflection, diffusion, or both within the light detection device.

2. The light detection device further includes a package that collectively houses the plurality of light detection region groups, 2. The photodetection device according to claim 1, wherein when the light pulse is incident on the first photodetection region of one of the plurality of photodetection region groups, a part of the light pulse is incident on the first photodetection region and the second photodetection region of at least one other of the photodetection region groups due to reflection, diffusion, or both within the package.

3. The first light detection regions are arranged in one or two rows, The light detection device according to claim 1 , wherein the second light detection regions are disposed in an area other than between the first light detection regions.

4. 4. The optical detection device according to claim 1, further comprising a light blocking member that prevents the optical pulse incident on the first optical detection region from directly entering the second optical detection region.

5. 5. The optical detection device according to claim 1, wherein in each optical detection region group, the optical sensitivity of the second optical detection region at the wavelength of the optical pulse is equal to the optical sensitivity of the first optical detection region at the same wavelength.

6. 5. The optical detection device according to claim 1, wherein in each optical detection region group, the optical sensitivity of the second optical detection region at the wavelength of the optical pulse is lower than the optical sensitivity of the first optical detection region at the wavelength.

7. 7. The light detection device according to claim 1, wherein in each light detection region group, a light receiving area of ​​the second light detection region is smaller than a light receiving area of ​​the first light detection region.

8. the first photodetection region and the second photodetection region are avalanche photodiodes, 5. The photodetection device according to claim 1, wherein in each photodetection region group, a multiplication factor of avalanche multiplication in the second photodetection region is smaller than a multiplication factor of avalanche multiplication in the first photodetection region.

9. 5. The light detection device according to claim 1, wherein the second light detection region of the plurality of light detection region groups has an element for attenuating incident light on a light receiving surface.

10. The photodetection device according to any one of claims 1 to 9, wherein a bias supply path for the first photodetection region of the plurality of photodetection region groups and a bias supply path for the second photodetection region of the plurality of photodetection region groups are common.

11. 10. The photodetection device according to claim 1, wherein bias supply paths for the first photodetection regions are electrically separated for each of the photodetection region groups.

12. 1. An apparatus for measuring a distance and a direction to a measurement object based on an incident position of the light pulse reflected on the measurement object and a time difference between when the light pulse is irradiated and when the reflected light pulse is incident, the apparatus comprising: a light emitting unit that emits the light pulse; a light detection unit that detects the light pulse reflected by the measurement object; Equipped with The light detection unit includes: a plurality of photodetection region groups each including a first photodetection region for detecting the optical pulse and a second photodetection region arranged alongside the first photodetection region; a signal generating circuit provided for each of the photodetection region groups, the signal generating circuit generating a signal corresponding to a difference between a first signal obtained by the first photodetection region and a second signal obtained by the second photodetection region; having a measurement device in which, when the light pulse is incident on the first light detection region of one of the multiple light detection region groups, a portion of the light pulse is incident on the first light detection region and the second light detection region of at least one other of the light detection region groups due to reflection, diffusion, or both within the measurement device.

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