Measuring device and light receiver

Abstract

To provide a measurement device which can flexibly respond to a specification that a system as an application target demands.SOLUTION: The measurement device includes a light projection unit and a light reception unit for receiving reflected light caused in a manner that the light projection unit projects light to a measurement target. The light reception unit includes a light reception part and a transmissive diffraction grating. The diffraction grating is arranged so that first reflected light from a first range of vision enters the light reception part as first-degree diffraction light and second reflected light from a second range of vision next to the first range of vision enters the light reception part as second-degree diffraction light.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a measuring device , and light receiver and particularly to a technique for expanding the visual field range of the measuring device.

Background Art

[0002] With the development of AD (Autonomous Driving) and ADAS (Advanced Driver Assistance System), as one of the measuring devices used for grasping the surrounding environment and estimating the self-position when a vehicle is running, the development / research of LiDAR (Light Detection and Ranging) is in progress. LiDAR includes a light projector that projects (irradiates) laser light onto a measurement target and a light receiver that receives the reflected light returned after the laser light is reflected by the measurement target, and provides information about the measurement target by measuring the distance to the measurement target based on the difference between the timing when the light projector emits the laser light and the timing when the light receiver receives the reflected light.

[0003] Patent Document 1 describes a LiDAR system configured for implementation in a vehicle. The LiDAR system includes a plurality of light emitters (such as VCSEL (Vertical Cavity Surface Emitting Laser) devices) that generate a plurality of optical beams. The LiDAR system converges the plurality of optical beams into a converged optical beam having a beam waist by a first lens, and projects the converged optical beam onto a target range by a second lens.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] One type of LiDAR is Flash LiDAR, which employs a method where a light source diffuses and illuminates a field of view with laser light. Because Flash LiDAR does not include mechanical components such as motors or MEMS (Micro Electro Mechanical Systems), it is attracting attention as a promising candidate for LiDAR in fields where durability is required, such as for automotive applications.

[0006] The field of view (FOV: field of view, beam profile, light distribution size) of the light receiver and light emitter of a flash LiDAR is determined by the size (area) of the light receiver and light emitter and the focal length of the optical system (light receiving optical system, light emitting optical system). Therefore, when applying flash LiDAR to individual systems such as vehicle range measuring sensors, it is necessary to configure the field of view so that it meets the specifications required by the system to which it is applied.

[0007] One way to extend the field of view of LiDAR when installed in a vehicle is to mount multiple LiDARs side-by-side. However, this would increase the number of components and the cost, which would be a challenge. Furthermore, it is necessary to flexibly respond to needs such as wanting to improve the measurement accuracy of a specific field of view (e.g., improving long-distance visibility in the direction of travel while driving).

[0008] This invention was made in view of the above background, and is a measuring device that can flexibly respond to the specifications required by the system to which it is applied. , and light receiver The purpose is to provide. [Means for solving the problem]

[0009] One aspect of the present invention for achieving the above objective is a measuring device comprising a light emitter and a light receiver that receives reflected light generated when the light emitter emits light toward a field of view, wherein the light receiver includes a light receiving section and a transmissive diffraction grating, and the diffraction grating is arranged such that first reflected light from a first field of view is incident on the light receiving section as first-order diffracted light, and second reflected light from a second field of view aligned with the first field of view is incident on the light receiving section as second-order diffracted light. The floodlight projects light onto the first field of view and the second field of view at different timings. .

[0011] Further issues disclosed in this application, and methods for solving them, will be made clear in the section on embodiments for carrying out the invention and in the drawings. [Effects of the Invention]

[0012] According to the present invention, a measuring device is capable of flexibly responding to the specifications required by the system to which it is applied. , and light receiver We can provide this. [Brief explanation of the drawing]

[0013] [Figure 1] This is a diagram showing the general configuration of the measuring device. [Figure 2A] This diagram illustrates the relationship between the light-receiving section, the light-receiving optical system, and the field of view. [Figure 2B] This diagram illustrates the relationship between the light-emitting unit, the light projection optical system, and the field of view. [Figure 3] This diagram illustrates the relationship between the photodetector and the field of view when a diffraction grating is used in the photodetector optical system. [Figure 4A] This diagram illustrates one configuration of a measuring device that can distinguish which field of view reflected light originated from. [Figure 4B] This figure shows one configuration of a diffraction grating. [Figure 5A] This figure shows the relationship between the field of view and the received image in the configuration shown in Figure 4A. [Figure 5B] This figure shows the relationship between the field of view and the received image when the orientation of the slits in the diffraction grating is not rotated around the optical axis. [Figure 6] This is a diagram for explaining parameters that determine the characteristics of a diffraction grating. [Figure 7] This is a diagram for explaining the relationship between a light projector and a viewing range when a diffraction grating is used in a light projection optical system.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the following description, the same or similar configurations may be denoted by the same reference numerals and redundant descriptions may be omitted. Further, in the following description, when it is necessary to distinguish between the same type of configurations, an identifier (such as an alphabet) may be appended after the reference numeral that collectively denotes the configuration.

[0015] FIG. 1 shows a schematic configuration (block diagram) of a measuring device 100 shown as an embodiment of the present invention. The measuring device 100 includes a light projector that projects (irradiates) light to be measured (irradiation light, light beam (laser light)) onto a measurement target, and a light receiver that receives reflected light (return light) that returns after the light to be measured is reflected by the measurement target, and functions as a flash LiDAR (Flash Light Detection and Ranging). The measuring device 100 measures the difference between the timing when the light projector emits the light to be measured and the timing when the light receiver receives the reflected light (the flight time of the laser light; hereinafter referred to as "TOF" (Time Of Flight)), and acquires information regarding the measurement target.

[0016] The measuring device 100 is mounted on, for example, a vehicle in which an AD (Autonomous Driving: autonomous driving system) or an ADAS (Advanced Driver Assistance System: advanced driver assistance system) is installed. The measuring device 100, for example, assists in detecting a person, another vehicle, and an object during the running of the vehicle, and provides various useful information to other devices and users in order to ensure the safety of the driver of the vehicle and the people present around the vehicle, and to reduce damage to the objects present around during the driving of the vehicle.

[0017] As shown in the figure, the exemplary measurement device 100 includes a light emitting unit 11, a light projecting control device 112, a current source 113, a light projecting optical system 14, a light receiving optical system 15, a light receiving unit 16, a TOF measurement device 117, an arithmetic device 150, and a communication I / F 160 (I / F: Interface). Among these, the light emitting unit 11, the light projecting control device 112, the current source 113, and the light projecting optical system 14 constitute a light projector, and the light receiving optical system 15 and the light receiving unit 16 constitute a light receiver.

[0018] The light emitting unit 11 that constitutes the light projector is configured using one or more light emitting elements, or one or more light emitting element arrays (for example, those in which the light emitting elements are arranged linearly (one-dimensionally) or two-dimensionally). The light emitting element is, for example, a laser diode, a surface-emitting type laser light emitting element (for example, VCSEL (Vertical Cavity Surface Emitting Laser). Hereinafter, referred to as a "surface-emitting element").), a surface-emitting element array (for example, a VCSEL array) in which a plurality of surface-emitting elements are arranged one-dimensionally or two-dimensionally on a substrate (such as a semiconductor substrate or a ceramic substrate), etc.

[0019] The light projecting control device 112 controls the current (drive current) supplied from the current source 113 to the light emitting element by generating a control signal for the current source 113 that supplies the drive current to the light emitting element constituting the light emitting unit 11 and inputting it to the current source 113. The light projecting control device 112 inputs a signal indicating the timing when the light emitting element emits light (the timing when the projected light is emitted from the light emitting element. Hereinafter, referred to as the "light projecting timing") to the TOF measurement device 117. The light projecting control device 112 causes the light emitting element to emit light periodically and repeatedly, for example, by performing control to periodically repeat the on / off of the current flowing through each of the light emitting elements.

[0020] The current source 113 supplies a current corresponding to the control signal input from the light projecting control device 112 to the light emitting element. The current source 113 supplies, for example, a periodic square-wave current for turning on and off the current flowing through each of the light emitting elements to the light emitting element.

[0021] The light projection optical system 14 adjusts the light distribution of the projected light by, for example, applying an optical effect (refraction, scattering, diffraction, etc.) to the projected light emitted from the light-emitting unit 11. The light projection optical system 14 is composed of, for example, various lenses such as collimating lenses and optical components such as reflectors (mirrors).

[0022] The light-receiving optical system 15 focuses the reflected light (backlight) that returns after the light emitted by the light emitter is reflected by the object to be measured 50, etc., onto the light-receiving unit 16. The light-receiving optical system 15 is composed of optical components such as various lenses such as focusing lenses, various filters such as wavelength filters, and reflectors (mirrors).

[0023] The light-receiving unit 16 is composed of one or more light-receiving elements, or one or more light-receiving element arrays (for example, in which light-receiving elements are arranged linearly (one-dimensionally) or planarly (two-dimensionally)). Examples of the light-receiving elements include photodiodes, SPADs (Single Photon Avalanche Diodes), and balanced photodetectors. The light-receiving unit 16 generates a current (hereinafter referred to as "receiving current") corresponding to the intensity of the reflected light by photoelectric conversion of the reflected light incident from the light-receiving optical system 15. The light-receiving unit 16 inputs a signal indicating the timing (hereinafter referred to as "receiving timing") when each light-receiving element constituting the light-receiving unit 16 receives reflected light, and the receiving current generated by each light-receiving element, to the TOF measuring device 117.

[0024] The TOF measuring device 117 determines the time of flight (TOF) based on a signal indicating the light emission timing input from the light emission control device 112 and a signal indicating the light reception timing input from the light receiving unit 16. The TOF measuring device 117 is configured, for example, using a time measurement IC (integrated circuit) equipped with a TDC (Time to Digital Converter) circuit. The TOF measuring device 117 inputs the determined TOF and the light reception current input from the light receiving unit 16 to the calculation unit 150.

[0025] The arithmetic unit 150 is composed of a processor (CPU (Central Processing Unit), MPU (Micro Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), DSP (Digital Signal Processor), etc.). Based on the received photocurrent and TOF input from the TOF measuring device 117, the arithmetic unit 150 generates information used for various measurements such as detection and distance measurement of the measurement target 50. This information includes, for example, a histogram used in time-correlated single-photon counting, the distance to each point of the measurement target 50, and a point cloud. The arithmetic unit 150 also controls the light projection control device 112 and the light receiving unit 16. For example, by controlling the light projection control device 112 and the light receiving unit 16, the arithmetic unit 150 controls the aforementioned light projection timing and light receiving timing so that the processing for histogram generation is accelerated or optimized. The information generated by the computing unit 150 is provided (transmitted) to devices that utilize the information (hereinafter referred to as "various utilization devices 40") via the communication interface 160.

[0026] The various devices 40 perform tasks such as creating environmental maps using point clouds and self-localization (SLAM (Simultaneous Localization and Mapping)) using scan matching algorithms (NDT (Normal Distributions Transform), ICP (Iterative Closest Point), etc.).

[0027] Figure 2A is a schematic diagram illustrating the relationship between the light-receiving unit 16, the light-receiving optical system 15, and the field of view 51. The field of view 51 is determined by the size (shape, size, and light-receiving area) of the light-receiving region of the light-receiving unit 16 and the focal length of the light-receiving optical system 15.

[0028] Figure 2B is a schematic diagram illustrating the relationship between the light-emitting unit 11, the light-projecting optical system 14, and the field of view 51. The field of view 51 is determined by the size (shape, size, and light-receiving area) of the light-emitting area of ​​the light-emitting unit 11 and the focal length of the light-projecting optical system 14.

[0029] Thus, the size of the field of view 51 is constrained by the size of the light-receiving unit 16 and the light-emitting unit 11. Therefore, the field of view when using, for example, off-the-shelf products as the light-receiving unit 16 and light-emitting unit 11 does not necessarily match the purpose and application of the system to which the measuring device 100 is applied. Furthermore, depending on the purpose and application of the measuring device 100, there may be a need to improve the measurement accuracy of a specific field of view compared to other field of view (for example, when applying flash LiDAR to AD or ADAS, there may be a need to improve the measurement accuracy in a specific field of view such as far away in the oncoming lane), and it is necessary to respond flexibly to such needs.

[0030] Therefore, in the measuring device 100 of this embodiment, the above-mentioned problems and needs are addressed by using a diffraction grating (diffractive optical element) as an element of the light-receiving optical system 15 of the light receiver or the light-emitting optical system 14 of the light emitter. The specific configuration for this purpose will be described below.

[0031] <When using a diffraction grating in the light-receiving optical system> Figure 3 illustrates the relationship between a photodetector and its field of view 51 (the first field of view 51a, the second field of view 51b, and the third field of view 51c, which are aligned in the +x direction in the figure) when a diffraction grating (diffractive optical element) is used in the photodetector's light-receiving optical system 15. In this figure, the elements of the photodetector (light-receiving optical system 15 and light-receiving unit 16) are depicted as viewed from a direction perpendicular to the optical axis of the light-receiving unit 16 (viewed from the +y side), while the field of view 51 is depicted as viewed from the direction of the optical axis (viewed from the -z side). The arrows in the figure represent the reflected light generated when the light emitter projects light from each field of view 51 (first field of view 51a, second field of view 51b, and third field of view 51c) toward each field of view 51, which is incident on the photodetector from each field of view. The size of the photodetector is exaggerated in this figure.

[0032] As shown in the figure, the light-receiving optical system 15 includes a diffraction grating 151 on which minute irregularities on the order of wavelength are periodically formed on the surface, and other optical systems 152 (various lenses, various filters, etc.). In this embodiment, the diffraction grating 151 is assumed to be a transmission-type phase grating.

[0033] As shown in the figure, reflected light incident on the diffraction grating 151 from the first field of view 51a (hereinafter referred to as "first reflected light") is incident on the other optical system 152 as +1 order diffracted light (first-order diffracted light). Also, reflected light incident on the diffraction grating 151 from the second field of view 51b adjacent to the first field of view 51a (hereinafter referred to as "second reflected light") is incident on the other optical system 152 as 0 order diffracted light (second-order diffracted light). Also, reflected light incident on the diffraction grating 151 from the third field of view 51c adjacent to the second field of view 51b (hereinafter referred to as "third reflected light") is incident on the other optical system 152 as -1 order diffracted light (third-order diffracted light). Then, each reflected light (the first reflected light, the second reflected light, and the third reflected light) that enters the other optical system 152 is focused onto the light-receiving unit 16.

[0034] In this way, by using a diffraction grating 151 as an element of the light-receiving optical system 15, reflected light from each field of view 51 (first field of view 51a, second field of view 51b, and third field of view 51c) can be focused onto the light-receiving unit 16. Therefore, the field of view (FOV) of the photodetector can be expanded without increasing the light-receiving area of ​​the light-receiving unit 16 (without increasing the number of light-receiving elements).

[0035] Furthermore, as shown in the figure, in this configuration, the reflected light (diffracted light) from each field of view 51 (first field of view 51a, second field of view 51b, and third field of view 51c) all enter the same light-receiving element of the light-receiving unit 16. For this reason, when implementing this in the measuring device 100, some mechanism is needed to distinguish which field of view 51 the reflected light from has been received.

[0036] The above mechanism can be realized, for example, by emitting light from the light emitter to each field of view 51 (first field of view 51a, second field of view 51b, third field of view 51c) at different timings for each field of view 51. In this case, for example, the computing device 150 controls the light emission control device 112 so that the light emission from the light emitter is performed at different timings for each field of view 51, and distinguishes which field of view 51 the reflected light came from based on the timing at which the light receiving element of the light receiving unit 16 receives the reflected light (hereinafter referred to as the "first method").

[0037] Alternatively, for example, the light emitter may select a portion of each field of view 51 (a portion of the first field of view 51a, a portion of the second field of view 51b, and a portion of the third field of view 51c, such that the reflected light (+1st order diffracted light, 0th order diffracted light, and -1st order diffracted light) from the first field of view 51a, the second field of view 51b, and the third field of view 51c, respectively, does not enter the same light-receiving element of the light-receiving unit 16), and emit light simultaneously to each selected portion (hereinafter referred to as the "second method"). According to the second method, since light can be received simultaneously in each portion of each field of view 51, the time required to emit light in all fields of view 51 (first field of view 51a, second field of view 51b, and third field of view 51c) can be shortened (scan speed).

[0038] Alternatively, as shown in Figure 4A, the light projector may be configured to simultaneously project light over a band-shaped region 55 spanning a first field of view 51a, a second field of view 51b, and a third field of view 51c, while the diffraction grating 151 may be positioned such that the direction of the arrangement of its slits 1511 (a unit of the grating consisting of convex and concave portions) is rotated by a predetermined angle α around the optical axis of the diffraction grating 151 (the Z-axis in Figure 4B) with respect to the extending direction of the band-shaped region 55 (hereinafter referred to as the "third method").

[0039] In this case, the thickness of the band-shaped region 55 (the distance in the y-direction (width) in the figure) is set to be shorter than the offset between adjacent field of view regions 51 (the amount of offset in the y-direction (step) between adjacent field of view regions 51 in the example shown in the figure) so that reflected light from different field of view regions 51 does not enter the light receiving unit 16 at the same time.

[0040] Figure 5A shows an example of the field of view 51 and the image of the reflected light focused on the light-receiving unit 16 (received image) when the third method is adopted. As shown in the figure, the reflected light from each field of view 51 (+1st order diffracted light, 0th order diffracted light, -1st order diffracted light) is focused on different light-receiving elements of the light-receiving unit 16.

[0041] Incidentally, if, for example, the optical axis of the diffraction grating 151 is aligned with the extension direction of the band-shaped region 55, as shown in Figure 5B, the reflected light from each field of view 51 (reflected light from the band-shaped region 55 of each field of view 51) will overlap and be focused simultaneously on the same light-receiving element of the light-receiving unit 16.

[0042] According to the third method described above, it is possible to simultaneously project and receive light over a band-shaped area 55 extending from the first field of view 51a to the third field of view 51c, thereby shortening the time required for projecting light over the entire field of view 51 (scan speed).

[0043] As described above, by using a diffraction grating 151 as an element of the light-receiving optical system 15, the field of view (FOV) of the photodetector can be easily extended to a range spanning from the first field of view 51a to the third field of view 51c without increasing the light-receiving area of ​​the light-receiving section 16 (without increasing the number of light-receiving elements).

[0044] By the way, the following relationship exists between the angle θ between the incident light and the diffracted light incident on the diffraction grating 151, the grating pitch d (grating spacing), the wavelength λ of the incident light, and the order of diffraction M. [Mathematics 1] M×λ=d×sinθ...Equation 1 Therefore, the field of view (FOV) of the photodetector can be adjusted by selecting the grating pitch d and the wavelength λ of the incident light. For example, if the wavelength λ of the incident reflected light is 905 nm, the diffraction angle θ of the diffraction grating 151 should be 40° (the field of view of the first field of view 51a being +20° to +60°, the field of view of the second field of view 51b being ±20°, and the field of view of the third field of view 51c being -20° to -60°), so the grating pitch d should be 1.4 μm.

[0045] Figure 6 is a diagram illustrating the parameters that determine the characteristics of the diffraction grating 151. The diffraction efficiency (transmittance) of the diffraction grating 151 is determined by the grating density shown in the figure (the proportion of the slit 1511 occupied by the convex portion 1511a) and the height of the convex portion 1511a. Therefore, by adjusting these values, the diffraction efficiency (the amount of reflected light incident on the light-receiving portion 16) of each reflected light (+1st order diffracted light, 0th order diffracted light, -1st order diffracted light) from each field of view 51 (first field of view 51a, second field of view 51b, third field of view 51c) can be adjusted.

[0046] For example, in a diffraction grating 151 constructed using a material with a refractive index of 1.5 (synthetic quartz, acrylic, etc.) and configured to have a diffraction angle of 40°, if the height of the convex portion 1511a is 0.724 μm and the grating density is 0.2, the amount of diffracted light is 21.8% for the +1st order diffracted light, 50% for the 0th order diffracted light, and 21.7% for the -1st order diffracted light, assuming the incident light intensity is 100%. Furthermore, in a diffraction grating 151 of the same material and diffraction angle, if the height of the convex portion 1511a is 0.905 μm and the grating density is 0.65, the amount of diffracted light is 31.1% for the +1st order diffracted light, 33.1% for the 0th order diffracted light, and 31.3% for the -1st order diffracted light, assuming the incident light intensity is 100%.

[0047] In this way, by selecting the grating pitch d of the diffraction grating 151 and the wavelength λ of the incident light, the field of view 51 (receiving range) of the photodetector can be adjusted to the field of view required by the system to which it is applied. Furthermore, by adjusting the values ​​of parameters such as the refractive index, grating density, and height of the protrusions 1511a of the diffraction grating 151, the diffraction efficiency (light quantity) of each diffracted light (+1st order diffracted light, 0th order diffracted light, -1st order diffracted light) emitted from the diffraction grating 151 can be adjusted. Therefore, it is possible to meet needs such as improving the measurement accuracy of a specific field of view, for example, to improve the long-distance visibility of the direction of travel while driving. Thus, the measurement device 100 of this embodiment can flexibly respond to the specifications required by the system to which it is applied.

[0048] <When using a diffraction grating in the light projection optical system> Figure 7 illustrates the relationship between the light projector and its field of view 51 (projection range) (first field of view 51a, second field of view 51b, third field of view 51c) when a diffraction grating 141, having the same configuration as the diffraction grating 151 used in the aforementioned light receiving optical system 15, is used in the light projection optical system 14 of the light projector of the measuring device 100. In this figure, the elements of the light projector (light projection optical system 14 and light-emitting unit 11) are depicted as viewed from a direction perpendicular to the optical axis of the light-emitting unit 11 (viewed from the +y side), and each field of view 51 is depicted as viewed from the direction of the optical axis (viewed from the -z side). The arrows shown in the figure represent the correspondence between each diffracted light emitted from the light projector and each field of view 51 (first field of view 51a, second field of view 51b, third field of view 51c). Furthermore, the size of the floodlights is exaggerated in the illustration.

[0049] The light projection optical system 14 includes a diffraction grating 141 and other optical systems 142 (various lenses, various filters, etc.). As shown in the figure, light emitted from the light-emitting unit 11 passes through the other optical systems 142 and enters the diffraction grating 141, thereby causing the diffraction grating 141 to emit +1st order diffracted light toward the first field of view 51a, 0th order diffracted light toward the second field of view 51b, and -1st order diffracted light toward the third field of view 51c.

[0050] In this way, by using a diffraction grating 141 as an element of the light projection optical system 14, the field of view (FOV) of the light projector can be easily extended to a range spanning from the first field of view 51a to the third field of view 51c without increasing the light-emitting area of ​​the light-emitting unit 11 (without increasing the number of light-emitting elements).

[0051] Furthermore, similar to the case where a diffraction grating 151 is used as the light receiver, the field of view 51 of the light projector can be adjusted by selecting the grating pitch d of the diffraction grating 141 and the wavelength λ of the incident light. In addition, the diffraction efficiency (light intensity) of each diffracted light (+1st order diffracted light, 0th order diffracted light, -1st order diffracted light) can be adjusted by adjusting the values ​​of parameters such as the refractive index, grating density, and height of the protrusions of the diffraction grating 141. Therefore, the measurement device 100 can flexibly respond to the specifications required by the system to which it is applied.

[0052] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments and includes various modifications. Furthermore, the above embodiments are described in detail to explain the configuration in an easy-to-understand manner and are not necessarily limited to those having all the configurations described. In addition, some of the configurations of the above embodiments can be added to, deleted from, or replaced with other configurations.

[0053] For example, although the above description has been based on the case where there are three fields of view (light projection range, light reception range) (first field of view 51a, second field of view 51b, and third field of view 51c), the present invention can also be applied when there are two fields of view or four or more.

[0054] Furthermore, for example, the configurations of the light emitter and light receiver described above (a configuration in which the diffraction grating 151 is used as an element of the light-receiving optical system 15, and a configuration in which the diffraction grating 141 is used as an element of the light-emitting optical system 14) may be applied to both of these configurations in the measuring device 100, or only one of them may be applied.

[0055] Furthermore, while the field of view was extended using diffracted light of three different orders (+1st order, 0th order, and -1st order) from a diffraction grating in the above example, the field of view may also be extended using diffracted light of other orders. [Explanation of Symbols]

[0056] 50 Measurement target, 51a First field of view, 51b Second field of view, 51c Third field of view 51, 100 Measurement device, 11 Light-emitting unit, 112 Light projection control device, 113 Current source, 14 Light projection optical system, 141 Diffraction grating, 142 Other optical systems, 15 Light-receiving optical system, 151 Diffraction grating, 1511a Convex part, 1511b Concave part, 152 Other optical systems, 16 Light-receiving unit, 117 TOF measurement device, 150 Computing unit

Claims

1. The system comprises a light emitter and a light receiver that receives reflected light generated when the light emitter emits light towards a field of view, The photodetector includes a light-receiving section and a transmissive diffraction grating. The diffraction grating is arranged such that first reflected light from a first field of view is incident on the light-receiving unit as first-order diffracted light, and second reflected light from a second field of view aligned with the first field of view is incident on the light-receiving unit as second-order diffracted light. The floodlight projects light onto the first field of view and the second field of view at different timings. Measuring device.

2. The system comprises a light emitter and a light receiver that receives reflected light generated when the light emitter emits light towards a field of view, The photodetector includes a light-receiving section and a transmissive diffraction grating. The first reflected light from the first field of view is incident on the light receiving unit as +1st order diffracted light. The second reflected light from the second field of view, which is aligned with the first field of view, is incident on the light receiving unit as zero-order diffracted light. The third reflected light from the third field of view, which is aligned in the direction from the first field of view to the second field of view, is incident on the light-receiving unit as -1st order diffracted light. They are arranged in such a way. Measuring device.

3. A measuring device according to claim 2, The floodlight projects light onto the first field of view, the second field of view, and the third field of view at different timings. Measuring device.

4. A measuring device according to claim 2, The light-receiving unit includes a plurality of light-receiving elements arranged in a planar manner. The diffraction grating is arranged such that the direction of the arrangement of its slits coincides with the direction of the arrangement from the first field of view to the third field of view. The light projector simultaneously projects light onto a portion of the first field of view, a portion of the second field of view, and a portion of the third field of view, such that the first reflected light, the second reflected light, and the third reflected light do not enter the light-receiving element. Measuring device.

5. A measuring device according to claim 2, The light-receiving unit includes a plurality of light-receiving elements arranged in a planar manner. The light emitter simultaneously emits light over a band-shaped area spanning from the first field of view to the third field of view. The diffraction grating is positioned such that the direction of the arrangement of its slits is rotated by a predetermined angle around the optical axis of the diffraction grating with respect to the extending direction of the band-shaped region, so that the first reflected light, the second reflected light, and the third reflected light each incident on different photodetectors. Measuring device.

6. A light receiver that receives reflected light generated when a light emitter emits light towards a field of view, and a light receiver that receives reflected light generated when a light emitter emits light towards a target to be measured, The photodetector includes a light-receiving section and a transmissive diffraction grating. The diffraction grating is The first reflected light from the first field of view is incident on the light receiving unit as +1st order diffracted light. The second reflected light from the second field of view, which is aligned with the first field of view, is incident on the light receiving unit as zero-order diffracted light. The third reflected light from the third field of view, which is aligned in the direction from the first field of view to the second field of view, is incident on the light-receiving unit as -1st order diffracted light. They are arranged in such a way. Receiver.

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