Detection device and detection method

Abstract

To provide a technology with which it is possible to heighten the functionality of a detection device or a detection method that detects things using light.SOLUTION: A detection device 100 comprises a transmission unit 1 that transmits light to a scan area A, and a reception unit 2 that receives light reflected at an object At present in the scan area A. The transmission unit 1 includes a first measurement light generation unit 11a that generates first measurement light La whose wavelength changes continuously from a first wavelength, a second measurement light generation unit 11b that generates second measurement light Lb whose wavelength changes continuously from a second wavelength that is different from the first wavelength, and a light guidance unit 13 that guides light L that includes at least one of the first measurement light La and the second measurement light Lb, causing it to scan the scan area A.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a detection device and a detection method that perform detection using light. [Background technology]

[0002] There are various detection technologies that use light, one of which is LiDAR (Light Detection And Ranging) technology (for example, Patent Document 1). With LiDAR technology, for example, light is irradiated onto an object, and the light that is reflected back from the object is detected to determine the distance to the object. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-184067 Summary of the Invention [Problem to be solved by the invention]

[0004] LiDAR technology has been rapidly developing in recent years, with technological developments aimed at miniaturizing LiDAR devices and reducing their costs. At the same time, there are expectations for the emergence of technology that will give LiDAR devices additional functions in addition to their basic function of detecting objects and measuring the distance to those objects, thereby enhancing their functionality.

[0005] An object of the present disclosure is to provide a technology that can achieve even higher functionality in a detection device or detection method that performs detection using light. [Means for solving the problem]

[0006] A first aspect is a detection device, comprising: a transmitter that transmits light to a scanning area; and a receiver that receives light reflected by an object in the scanning area. A control unit;the transmitting unit includes a first measuring light generating unit that generates a first measuring light whose wavelength changes continuously from a first wavelength, a second measuring light generating unit that generates a second measuring light whose wavelength changes continuously from a second wavelength different from the first wavelength, and a light guiding unit that guides light including at least one of the first measuring light and the second measuring light to scan the scanning region. The receiving unit includes a first photodetector that detects the first measurement light reflected by the object, and a second photodetector that detects the second measurement light reflected by the object, and the control unit calculates a distance to the object based on at least one of a detection result of the first photodetector and a detection result of the second photodetector, and identifies a type of the object based on a detection result of the first photodetector and a detection result of the second photodetector. do.

[0007] A second aspect is the detection device according to the first aspect, wherein the transmitter comprises a combining unit, which combines the first measurement light and the second measurement light to form an aggregate light, and causes the aggregate light to enter the light guiding unit; and the receiver comprises a branching unit which branches the aggregate light reflected by the object; a first filter, which is disposed on the optical path of one of the branched aggregate light beams, and attenuates frequency bands other than the frequency band corresponding to the first measurement light beam and passes the frequency band corresponding to the first measurement light; and a second filter, which is disposed on the optical path of another of the branched aggregate light beams, and attenuates frequency bands other than the frequency band corresponding to the second measurement light beam and passes the frequency band corresponding to the second measurement light. wherein the first photodetector is Detecting light that has passed through the first filter The second photodetector is Detecting light that has passed through the second filter do.

[0008] A third aspect is the detection device according to the second aspect, The control unit The optical system includes a first reflectance specifying unit that specifies a first reflectance, which is the reflectance of the object at the first wavelength, based on the detection result of the first photodetector; a second reflectance specifying unit that specifies a second reflectance, which is the reflectance of the object at the second wavelength, based on the detection result of the second photodetector; and a type identifying unit that identifies the type of the object based on the first reflectance and the second reflectance.

[0009] A fourth aspect is the detection device according to the third aspect, The control unitThe device is provided with a memory unit that stores reflectance data describing, for each of one or more candidate types, the reflectance of the candidate type at the first wavelength and the reflectance of the candidate type at the second wavelength, and the type identification unit compares the reflectance of the object with the reflectance of the candidate type for each of the first wavelength and the second wavelength to determine whether the object is of the candidate type.

[0010] A fifth aspect is a detection device according to any one of the first to fourth aspects, wherein the light guiding unit includes a spatial phase modulation element having a plurality of grating elements and modulating the phase of incident light by displacing each of the plurality of grating elements to guide the light.

[0011] A sixth aspect is a detection method, comprising: a transmitting step of transmitting light to a scanning area; and a receiving step of receiving light reflected from an object in the scanning area; a calculation step of performing calculation processing based on the detection result acquired in the receiving step; the transmitting step comprises a measurement light generating step of generating a first measurement light whose wavelength changes continuously from a first wavelength, and generating a second measurement light whose wavelength changes continuously from a second wavelength different from the first wavelength; a combining step of combining the first measurement light and the second measurement light to form aggregate light; and a light guiding step of guiding the aggregate light to scan the scanning area; the receiving step comprises a branching step of branching the aggregate light reflected by the object; and a light detecting step of detecting one aggregate light of the branched plurality of aggregate light after attenuating a frequency band other than a frequency band corresponding to the first measurement light, and detecting another aggregate light of the branched plurality of aggregate light after attenuating a frequency band other than a frequency band corresponding to the second measurement light. the calculation step includes a measurement data calculation step of calculating a distance to the object based on at least one of the detection results of the first measurement light and the second measurement light, and a type identification step of identifying the type of the object based on the detection results of the first measurement light and the second measurement light. do. [Effects of the Invention]

[0012] According to the first aspect, the transmitter includes a plurality of measurement light generators each generating measurement light beams in different wavelength ranges. This allows the reflected light beams resulting from scanning a scanning area with the plurality of measurement light beams in different wavelength ranges to be acquired in parallel or alternatively. This allows the device to have additional functions in addition to the basic function of detecting an object and measuring the distance to the object, thereby achieving even higher functionality. For example, by acquiring detection results for the same object using a plurality of measurement light beams in different wavelength ranges, it is possible to derive information other than the distance to the object (e.g., the type of object). Furthermore, by switching the measurement light beam used in response to changes in the environment in which the detection device is used, the status within the device, and other factors, the device can flexibly respond to such changes.

[0013] According to the second aspect, with a simple configuration, it is possible to acquire, in parallel, reflected light beams obtained by scanning a scanning region with a plurality of measurement light beams having mutually different wavelength ranges.

[0014] According to the third aspect, the type of object is identified based on the reflectance of the object at each of a plurality of wavelengths different from one another, so that the type of object can be identified with sufficient accuracy.

[0015] According to the fourth aspect, the type of the object can be easily identified.

[0016] According to the fifth aspect, it is possible to appropriately guide light whose wavelength changes continuously.

[0017] According to the sixth aspect, it is possible to acquire, in parallel, reflected light beams obtained by scanning the scanning region with a plurality of measurement light beams having mutually different wavelength ranges. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a block diagram showing a schematic configuration of a detection device according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing the hardware configuration of a control unit. [Figure 3]FIG. 2 is a plan view schematically showing a part of a grating light valve. [Figure 4] FIG. 1 is a side view schematically showing a grating light valve. [Figure 5] FIG. 2 is a schematic diagram for explaining the operation of a grating light valve. [Figure 6] 2 is a diagram showing a schematic of the optical system of the detector seen along the direction in which the line beam is directed; FIG. [Figure 7] FIG. 2 is a diagram schematically illustrating an optical system of the detection device as viewed along the extending direction of a line beam. [Figure 8] FIG. 2 is a block diagram showing a configuration related to type identification. [Figure 9] FIG. 10 is a diagram schematically illustrating an example of reflectance characteristics. [Figure 10] FIG. 10 is a diagram illustrating an example of the flow of operations of the detection device. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments will be described with reference to the accompanying drawings. Note that the components described in the embodiments are merely examples and are not intended to limit the scope of the present disclosure. Furthermore, in the drawings, the dimensions or number of each part may be exaggerated or simplified as necessary for ease of understanding.

[0020] Unless otherwise specified, expressions indicating relative or absolute positional relationships (e.g., "in one direction," "along one direction," "parallel," "orthogonal," "center," "concentric," "coaxial," etc.) not only express the exact positional relationship but also express a state of relative displacement in terms of angle or distance within a range that provides tolerance or equivalent functionality. Furthermore, expressions indicating an equal state (e.g., "identical," "equal," "homogeneous," etc.) not only express a state of strict quantitative equality but also express a state of difference that provides tolerance or equivalent functionality, unless otherwise specified. Furthermore, expressions indicating shape (e.g., "circular," "square," "cylindrical," etc.) not only express a strict geometrical shape but also express a shape within a range that provides equivalent functionality, such as irregularities or chamfers, unless otherwise specified. Furthermore, expressions such as "comprise," "include," "have," "include," and "have" regarding components are not exclusive expressions that exclude the presence of other components. Furthermore, the expression "at least one of A, B, and C" includes "A only," "B only," "C only," "any two of A, B, and C," and "all of A, B, and C."

[0021] <1. Schematic configuration of the detection device> The schematic configuration of a detection device 100 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the schematic configuration of the detection device 100.

[0022] The detection device 100 is a device that performs detection and ranging using light (a so-called LiDAR device), and is equipped with a transmitter 1 that transmits light (light beam) to an area (scanning area) A surrounding the detection device 100, a receiver 2 that receives light transmitted from the transmitter 1 to the scanning area A and reflected by an object At in the scanning area A, and a controller 3 that controls these parts 1 and 2.

[0023] (Transmitter 1) The transmitter 1 includes a plurality of (three in the illustrated example) measurement light generators 11a, 11b, and 11c, a junction unit 12, and a light guide unit .

[0024] The first measurement light generation unit 11a generates a first measurement light beam La whose wavelength changes continuously from a first wavelength λa. The first wavelength λa can be selected as appropriate. For example, wavelengths suitable for use in a LiDAR device (i.e., wavelengths that can satisfy requirements such as being less susceptible to sunlight and ensuring safety to human eyes) include 532 nm, 850 nm, 905 nm, 1064 nm, and 1550 nm. Any of these wavelengths may be selected as the first wavelength λa.

[0025] The second measurement light generator 11b generates a second measurement light beam Lb whose wavelength changes continuously from a second wavelength λb different from the first wavelength λa. The second wavelength λb can also be selected appropriately. For example, a wavelength that is suitable for use in a LiDAR device and is different from the first wavelength λa may be selected as the second wavelength λb.

[0026] The third measurement light generator 11c generates a third measurement light beam Lc whose wavelength changes continuously from a third wavelength λc that is different from both the first wavelength λa and the second wavelength λb. The third wavelength λc can also be selected appropriately. For example, the third wavelength λc may be a wavelength that is preferably used in a LiDAR device and is different from the first wavelength λa and the second wavelength λb.

[0027] The converging unit 12 converges the measurement light beams La, Lb, and Lc emitted from the measurement light generating units 11 a, 11 b, and 11 c to form a collective light beam L, and causes the collective light beam L to enter the light guiding unit 13.

[0028] The light guiding unit 13 guides the collective light beam L incident thereon to scan the scanning area A. Specifically, the light guiding unit 13 includes, for example, a spatial phase modulation element 131, which is a type of phase modulation type spatial light modulator. The spatial phase modulation element 131 has a plurality of grating elements, and modulates the phase of the incident light beam by displacing each of the plurality of grating elements, thereby guiding the light beam.

[0029] (Receiver 2) The receiving unit 2 includes a branching unit 21, multiple (the same number as the measurement light generating units 11a, 11b, 11c included in the transmitting unit 1, three in the illustrated example) photodetectors 22a, 22b, 22c, and filters 23a, 23b, 23c arranged between the branching unit 21 and each photodetector 22a, 22b, 22c.

[0030] The branching unit 21 branches the collective light beam L, which is irradiated onto the scanning area A and reflected by the object At therein, into the same number of light detectors 22a, 22b, 22c (i.e., the same number as the measurement light generating units 11a, 11b, 11c provided in the transmitting unit 1, three in the example shown).

[0031] The first filter 23a is disposed on the optical path of one of the branched aggregate light beams L (first aggregate light beam L1), and attenuates frequency bands other than the frequency band corresponding to the first measurement light beam La, while passing the frequency band corresponding to the first measurement light beam La, causing it to be incident on the first photodetector 22a. Meanwhile, the first photodetector 22a detects the incident light (i.e., the light beam that has passed through the first filter 23a). That is, the first photodetector 22a detects the first measurement light beam La that is irradiated onto the scanning area A and reflected by the object At located therein.

[0032] Similarly, the second filter 23b is disposed on the optical path of another one (second aggregate light beam L2) of the split aggregate light beams L, and attenuates frequency bands other than that corresponding to the second measurement light beam Lb, while passing the frequency band corresponding to the second measurement light beam Lb, causing it to be incident on the second photodetector 22b. Meanwhile, the second photodetector 22b detects the incident light (i.e., the light beam that has passed through the second filter 23b). That is, the second photodetector 22b detects the second measurement light beam Lb that is irradiated onto the scanning area A and reflected by the object At located therein.

[0033] Similarly, the third filter 23c is arranged on the optical path of the remaining one of the split aggregate light beams L (the third aggregate light beam L3), and attenuates frequency bands other than that corresponding to the third measurement light beam Lc while passing the frequency band corresponding to the third measurement light beam Lc to make it incident on the third photodetector 22c. Meanwhile, the third photodetector 22c detects the incident light (i.e., the light beam that has passed through the third filter 23c). That is, the third photodetector 22c detects the third measurement light beam Lc that is irradiated onto the scanning area A and reflected by the object At located therein.

[0034] (Control Unit 3) The control unit 3 is an element that controls the operations of the units 1 and 2 included in the detection device 100 and performs various types of arithmetic processing, and is configured, for example, by a general computer having an electric circuit, a microcomputer, or the like.

[0035] Specifically, the control unit 3 includes a processor such as a central processor unit (CPU) 31 as a central processing unit responsible for data processing, or an FPGA (Field Programmable Gate Array), as shown in Fig. 2. The control unit 3 further includes a read-only memory (ROM) 32 in which a basic program and the like are stored, a random access memory (RAM) 33 used as a working area when the CPU 31 performs predetermined processing (data processing), a storage device 34 configured by a nonvolatile storage device such as a flash memory or a hard disk drive, and a bus line 35 connecting these devices to each other.

[0036] The storage device 34 stores a program P that defines the processing to be executed by the control unit 3, and the CPU 31 executes this program P, allowing the control unit 3 to execute the processing defined by the program P. However, some or all of the processing executed by the control unit 3 may be executed by hardware such as a dedicated logic circuit (for example, a dedicated processor). The storage device 34 also stores various data used for arithmetic processing and the like.

[0037] The control unit 3 may further be connected to a display unit 36 ​​that displays various information, an input unit 37 that accepts input operations from an operator, etc. Various display devices such as a liquid crystal display may be used as the display unit 36. Furthermore, a keyboard, a mouse, a touch panel, a microphone, etc. may be used as the input unit 37.

[0038] <2. Configuration of the detection device> Next, a specific configuration example of the detection device 100 will be described. First, a configuration example of the spatial phase modulation element 131 provided in the light guiding unit 13 will be described below, and then a configuration example of the entire detection device 100 including the spatial phase modulation element 131 will be described.

[0039] <2-1. Spatial phase modulation element> As described above, the spatial phase modulation element 131 has a plurality of grating elements, and performs phase modulation on the incident light beam by displacing each of the plurality of grating elements, thereby guiding the light beam. In this embodiment, the spatial phase modulation element 131 is realized using a grating light valve 5, which is a type of optical phase array (optical phased array).

[0040] The grating light valve 5 will be described with reference to Figs. 3 to 5. Fig. 3 is a plan view schematically showing a part of the grating light valve 5. Fig. 4 is a side view schematically showing the grating light valve 5. Fig. 5 is a diagram for explaining the operation of the grating light valve 5.

[0041] The grating light valve 5 includes a base portion 51 and a plurality of ribbons 52 (for example, several thousand ribbons).

[0042] The base portion 51 includes a substrate 511 and an electrode (base electrode) 512. The substrate 511 is a plate-shaped base material, and is configured using, for example, a silicon substrate. On the other hand, the base electrode 512 is an electrode provided on the substrate 511, and is realized by, for example, a metal film formed on the upper surface of the substrate 511 (the main surface on which the ribbons 52 are provided).

[0043] Each of the multiple ribbons 52 serves as a grating element in the grating light valve 5. The multiple ribbons 52 are arranged in a row on one main surface of the substrate 511. Each ribbon 52 has an elongated shape in a plan view, and is arranged with its longitudinal direction perpendicular to the arrangement direction. For ease of explanation, FIGS. 3 to 5 show a coordinate system in which the arrangement direction of the multiple ribbons 52 is designated "Gx" and the longitudinal direction of each ribbon 52 is designated "Gy."

[0044] Each ribbon 52 is flexible, and is connected to the main surface of substrate 511 at both ends in the longitudinal direction, with a gap provided between ribbon 52 and substrate 511 at the center in the longitudinal direction. Each ribbon 52 also has a reflective surface 521 that specularly reflects a light beam, provided on its upper surface (the surface opposite to the surface facing substrate 511). The reflective surface 521 is realized by, for example, a thin film of metal (e.g., aluminum) formed on the upper surface of ribbon 52. Each ribbon 52 also has an electrode (ribbon electrode) 522. The ribbon electrode 522 is realized by, for example, a thin film of metal that realizes the reflective surface 521. Needless to say, a thin film or the like that realizes ribbon electrode 522 may be provided separately from the thin film that realizes reflective surface 521.

[0045] As described above, each ribbon 52 is flexible. Therefore, when a potential difference is applied between the base electrode 512 and the ribbon electrode 522, the ribbon 52 is bent toward the substrate 511 by electrostatic force and displaced in the normal direction of the substrate 511 (the state shown by the dashed line in FIG. 4). When the potential difference between the two electrodes 512 and 522 is eliminated, the electrostatic force is eliminated and the ribbon 52 elastically returns to its unbent state (the state shown by the solid line in FIG. 4). A potential difference is applied between the two electrodes 512 and 522 in response to a signal from the control unit 3, and each ribbon 52 is displaced relative to the substrate 511 by an amount corresponding to the applied potential difference. In other words, the displacement amount ΔG of the ribbon 52 relative to the substrate 511 is controlled by a signal from the control unit 3.

[0046] In the grating light valve 5, the displacement ΔG of each of the ribbons 52 is controlled by a signal from the control unit 3, allowing the ribbons 52 to form various modes (patterns). For example, the grating light valve 5 can form a pattern in which the displacement ΔG of the ribbons 52 is all zero (first mode M1). In this case, the grating light valve 5 functions as a mirror, and light incident on the grating light valve 5 is specularly reflected. Furthermore, for example, the grating light valve 5 can form a blaze pattern in which the displacement ΔG of the ribbons 52 changes periodically along the arrangement direction of the ribbons 52 (second mode M2, third mode M3). Needless to say, the grating light valve 5 can form blaze patterns with any blaze period (displacement period) B and any blaze angle (the angle the inclined surface of the sawtooth shape forms with the substrate 511) in addition to the second mode M2 ​​and third mode M3 exemplified in the figure. When the multiple ribbons 52 form a blaze pattern along the arrangement direction, the grating light valve 5 functions as a blazed diffraction grating. That is, the grating light valve 5 at this time modulates the phase of the light beam incident thereon and reflects the light beam at an angle according to the blaze period B. Therefore, by successively changing the blaze period B of the blaze pattern formed by the multiple ribbons 52 (by cycling the blaze period B), it is possible to successively change the angle at which the light beam is reflected from the grating light valve 5. In this way, by successively changing the direction in which the light beam is emitted, the light beam can be guided to scan the scan area A.

[0047] <2-2. Overall configuration of the detection device> Next, the overall configuration of the detection device 100 will be described with reference to FIGS. 6 and 7. As will become clear from the following description, the transmitter 1 of the detection device 100 shapes a light beam so as to expand in a predetermined direction, and irradiates the light beam onto a linear region extending one-dimensionally in the scanning region A (a light beam that expands in a predetermined direction and irradiates a linear region extending in the predetermined direction with light will hereinafter be referred to as a "line beam"). Meanwhile, the transmitter 1 guides the line beam in a direction intersecting the direction in which it extends (here, a direction perpendicular to the direction in which it extends). As a result, the two-dimensional scanning region A (i.e., the two-dimensional scanning region A defined by the direction in which the line beam is guided and the direction in which the line beam extends) is scanned with the light beam (so-called one-dimensional line scanning method). FIG. 6 is a diagram showing a schematic view of the optical system of the detection device 100 as viewed along the direction Ax in which the line beam is guided (hereinafter also referred to as the "first direction"), and FIG. 7 is a diagram showing a schematic view of the optical system of the detection device 100 as viewed along the direction Ay in which the line beam extends (hereinafter also referred to as the "second direction").

[0048] Each of the plurality of measurement light generating units 11a, 11b, and 11c includes a light source including, for example, a laser light source and a wavelength sweeping unit that continuously changes the wavelength (frequency) of the light beam (so-called wavelength swept light source), and each light beam emitted from the light source is wavelength swept (frequency swept) by the wavelength sweeping unit to generate measurement light beams La, Lb, and Lc whose wavelength (frequency) changes continuously. The wavelength change width (sweep width) may be appropriately specified and may be, for example, about several nm.

[0049] As described above, the measurement light generators 11a, 11b, and 11c generate and emit measurement light beams La, Lb, and Lc whose wavelengths change continuously from the mutually different wavelengths λa, λb, and λc. That is, the light source included in the first measurement light generator 11a emits a light beam of the first wavelength λa, and the first measurement light generator 11a performs wavelength sweep on the light beam of the first wavelength λa emitted from the light source to generate the first measurement light beam La whose wavelength changes continuously from the first wavelength λa. Similarly, the light source included in the second measurement light generator 11b emits a light beam of the second wavelength λb, and the second measurement light generator 11b performs wavelength sweep on the light beam of the second wavelength λb emitted from the light source to generate the second measurement light beam Lb whose wavelength changes continuously from the second wavelength λb. Similarly, the light source provided in the third measurement light generating unit 11c emits a light beam of the third wavelength λc, and the third measurement light generating unit 11c performs wavelength sweeping on the light beam of the third wavelength λc emitted from the light source to generate a third measurement light beam Lc whose wavelength changes continuously from the third wavelength λc.

[0050] When viewed along the first direction Ax (FIG. 6), the measurement light beams La, Lb, and Lc emitted from the measurement light generators 11a, 11b, and 11c are collimated in the second direction Ay by a cylindrical lens 101. A beam splitter 102 is provided after the cylindrical lens 101, and this beam splitter 102 splits the collimated measurement light beams La, Lb, and Lc into measurement light beams La, Lb, and Lc and reference light beams L0a, L0b, and L0c. Like the measurement light beams La, Lb, and Lc, the reference light beams L0a, L0b, and L0c are light beams whose wavelengths change continuously, and are sent to the receiver 2 and used to acquire beat signals.

[0051] Subsequently, the multiple measurement light beams La, Lb, and Lc are joined (i.e., guided onto the same optical axis) at a joining section 12 including, for example, a mirror, to form a collective light beam L. In the example shown in the figure, the measurement light beams La, Lb, and Lc are joined from the second direction Ay, but the measurement light beams La, Lb, and Lc may also be joined from the first direction Ax.

[0052] The collective light beam L is then focused by the lens 103 at the center of the spatial phase modulator 131 in the second direction Ay. As described above, the spatial phase modulator 131 is realized using the grating light valve 5, and the grating light valve 5 is arranged so that the arrangement direction Gx of the ribbons 52 is parallel to the first direction Ax and the extension direction Gy of each ribbon 52 is parallel to the second direction Ay. Therefore, the collective light beam L is focused by the lens 103 in the extension direction Gy of each ribbon 52 and focused at the center of the extension direction Gy. The displacement amount ΔG of each ribbon 52 is controlled with particularly high precision in the central region of the extension direction Gy of the ribbons 52, and by configuring the collective light beam L to be incident on this central region, it is possible to control the angle (scanning angle) of the collective light beam L reflected from the spatial phase modulator 131 with sufficiently high precision.

[0053] The collective light beam L reflected by the spatial phase modulator 131 enters the lens 104, is collimated in the second direction Ay by the lens 104, and is then imaged in the second direction Ay by the lens 105. The image point at which the collective light beam L is imaged by the lens 105 is defined between the lens 105 and the scanning area A. Therefore, the collective light beam L enters the scanning area A while expanding in the second direction Ay. In other words, the projection optical system including the group of lenses 104 and 105 shapes the collective light beam L so that it expands in the second direction Ay, and irradiates the scanning area A with it.

[0054] On the other hand, when viewed along the second direction Ay (FIG. 7), the measurement light beams La, Lb, and Lc emitted from the measurement light generators 11a, 11b, and 11c are incident on the cylindrical lens 101, but the cylindrical lens 101 has no power in the first direction Ax. Therefore, the measurement light beams La, Lb, and Lc emitted from the measurement light generators 11a, 11b, and 11c travel in the first direction Ax without being refracted by the cylindrical lens 101.

[0055] Next, the measurement light beams La, Lb, and Lc are converged at the convergence section 12 to form a collective light beam L, which then enters the lens 103 and is collimated in the first direction Ax by the lens 103 before entering the spatial phase modulator 131. That is, the collective light beam L enters an elongated strip-shaped region extending along the arrangement direction Gx of each ribbon 52 of the grating light valve 5 that implements the spatial phase modulator 131. As described above, in the grating light valve 5, the displacement amount ΔG of each of the multiple ribbons 52 is controlled by a signal from the control section 3, thereby performing phase modulation on the collective light beam L, and the collective light beam L is reflected at an angle (scanning angle) corresponding to the displacement mode (mode) of the multiple ribbons 52. FIG. 7 also shows the collective light beam L reflected at two different angles.

[0056] The collective light beam L reflected by the spatial phase modulator 131 enters the lens 104, is imaged in the first direction Ax by the lens 104, and is then collimated in the first direction Ax by the lens 105. In other words, the projection optical system including the group of lenses 104 and 105 shapes the collective light beam L emitted from the spatial phase modulator 131 so as to narrow it in the first direction Ax, and irradiates the scanning area A with the shaped light beam.

[0057] As described above, the scanning area A is irradiated with the collective light beam L that is expanded in the second direction Ay and narrowed in the first direction Ax (i.e., the collective light beam L that has been shaped into a line beam extending in the second direction Ay). Meanwhile, the spatial phase modulator 131 successively changes the angle at which the collective light beam L is reflected. This causes the collective light beam L to be guided in a direction (first direction Ax) perpendicular to its extending direction (second direction Ay), and the two-dimensional scanning area A defined by both directions Ax and Ay is scanned with the collective light beam L. The size of the scanning area A, i.e., the field of view (FOV) of the detection device 100, is determined by the length in the extending direction of the collective light beam L that has been made into a line beam and the guidance range (scanning angle range) of the collective light beam L by the light guiding unit 13.

[0058] Continuing, looking along the second direction Ay (FIG. 7), the collective light beam L irradiated onto the scanning area A and reflected by an object At present therein is received through the camera lens 201 or the like and branched into a plurality of beams (the same number as the photodetectors 22a, 22b, 22c provided in the receiving unit 2, three in the illustrated example) by the branching unit 21 configured including a beam splitter or the like. Note that, in the illustrated example, the collective light beam L is branched into a plurality of beams in the first direction Ax, but the collective light beam L may be branched into a plurality of beams in the second direction Ay.

[0059] The first aggregate light beam L1, which is one of the multiple branched aggregate light beams L, passes through the first filter 23a and enters the first photodetector 22a. As described above, the first filter 23a is a filter that attenuates frequency bands other than the frequency band corresponding to the first measurement light beam La and passes the frequency band corresponding to the first measurement light beam La, and is specifically configured, for example, by a bandpass filter. Therefore, the first aggregate light beam L1 including the multiple measurement light beams La, Lb, and Lc is incident on the first photodetector 22a after the frequency bands other than the frequency band corresponding to the first measurement light beam La are attenuated by the first filter 23a. In other words, the light beam that passed through the first filter 23a, i.e., the first measurement light beam La that was irradiated onto the scanning area A and reflected therefrom, enters the first photodetector 22a.

[0060] Similarly, the second aggregate light beam L2, which is another one of the multiple branched aggregate light beams L, passes through the second filter 23b and enters the second photodetector 22b. As described above, the second filter 23b is a filter that attenuates frequency bands other than the frequency band corresponding to the second measurement light beam Lb and passes the frequency band corresponding to the second measurement light beam Lb, and is specifically configured, for example, by a bandpass filter. Therefore, the second aggregate light beam L2 including the multiple measurement light beams La, Lb, and Lc is incident on the second photodetector 22b after the frequency bands other than the frequency band corresponding to the second measurement light beam Lb are attenuated by the second filter 23b. In other words, the light beam that passed through the second filter 23b, i.e., the second measurement light beam Lb that was irradiated onto the scanning area A and reflected therefrom, enters the second photodetector 22b.

[0061] Similarly, the third aggregate light beam L3, which is one of the remaining split aggregate light beams L, passes through the third filter 23c and enters the third photodetector 22c. As described above, the third filter 23c is a filter that attenuates frequency bands other than the frequency band corresponding to the third measurement light beam Lc and passes the frequency band corresponding to the third measurement light beam Lc. Specifically, the third filter 23c is, for example, a bandpass filter. Therefore, the third aggregate light beam L3 including the multiple measurement light beams La, Lb, and Lc enters the third photodetector 22c after the frequency bands other than the frequency band corresponding to the third measurement light beam Lc are attenuated by the third filter 23c. In other words, the light beam that passed through the third filter 23c, i.e., the third measurement light beam Lc that was irradiated onto the scanning area A and reflected therefrom, enters the third photodetector 22c.

[0062] When viewed along the first direction Ax (FIG. 6), each of the photodetectors 22a, 22b, and 22c includes, for example, a so-called one-dimensional photodetector array in which multiple photodetectors (light-receiving elements) 221 are arranged one-dimensionally (in one row), and the arrangement direction of the photodetectors 221 is arranged parallel to the second direction Ay. As described above, the collective light beam L irradiated onto the scanning area A is a line beam extending in the second direction Ay, and the collective light beam L returning from the scanning area A, and thus each of the measurement light beams La, Lb, and Lc after passing through the filters 23a, 23b, and 23c, are also similar line beams. In other words, each of the measurement light beams La, Lb, and Lc, which are line beams extending in the second direction Ay, is incident on multiple photodetectors 221 arranged in the second direction Ay in each of the photodetectors 22a, 22b, and 22c. Therefore, each photodetector 221 detects the light intensity of each measurement light beam La, Lb, Lc at each position in the second direction Ay.

[0063] The detection results from each of the plurality of photodetectors 22a, 22b, and 22c are transmitted to the control unit 3, and the control unit 3 performs various calculation processes using the detection results.

[0064] For example, the control unit 3 calculates various measurement data (e.g., the distance to the object At, the position of the object At, etc.) related to the object At in the scanning area A based on the detection result of at least one photodetector selected from the multiple photodetectors 22a, 22b, and 22c. Specifically, the control unit 3 calculates the measurement data using a frequency modulation continuous wave (FMCW) distance measurement technique. In this case, the control unit 3 superimposes a detection signal of the first measurement light beam La acquired by at least one selected photodetector (e.g., the first photodetector 22a) on a detection signal of a reference light beam L0a branched from the first measurement light beam La before it is irradiated onto the scanning area A, to obtain a detection signal of a composite wave of the two light beams La and L0a. This composite wave includes a beat signal generated by interference between the first measurement light beam La and the reference light beam L0a. The control unit 3 determines the frequency difference between the two light beams La and L0a based on the beat signal and calculates the distance to the object At from the frequency difference. Furthermore, for example, the control unit 3 identifies the position of the object At in the first direction Ax based on the scanning angle (the guide position of the collective light beam L by the light guide unit 13) when the first measurement light beam La reflected by the object At is projected onto the scanning area A. Furthermore, for example, the control unit 3 identifies the position of the object At in the second direction Ay based on the arrangement position of the photodetector 221 that detected the first measurement light beam La reflected by the object At.

[0065] Furthermore, for example, the control unit 3 identifies (recognizes) the type of the target object At based on the detection results of the multiple photodetectors 22a, 22b, and 22c. This point will be explained next.

[0066] <3. Identification of species> As described above, in the detection device 100, the control unit 3 identifies the type of object At present in the scanning area A based on the detection results of the multiple photodetectors 22a, 22b, and 22c. Here, the type of object At is identified by utilizing the property that many objects have unique reflectance characteristics for each type. The "reflectance characteristics" here refer to the reflectance for each wavelength (the transition of reflectance with respect to wavelength). FIG. 9 schematically illustrates, as examples, the reflectance characteristics (T1) of "plants," (T2) of "concrete," and (T3) of "asphalt." As illustrated in this figure, the reflectance characteristics are unique to each type of object and vary depending on the type. Therefore, the detection device 100 identifies the reflectances Ra, Rb, and Rc of the object At at each of the multiple wavelengths λa, λb, and λc from the detection results of the multiple photodetectors 22a, 22b, and 22c, and identifies the type of the object At from the reflectance characteristics estimated from the multiple reflectances Ra, Rb, and Rc.

[0067] The configuration of the detection device 100 related to type identification will be described with reference to Fig. 8. Fig. 8 is a block diagram showing the configuration related to type identification.

[0068] As a configuration related to type identification, the control unit 3 includes a plurality of reflectance specifying units 301a, 301b, and 301c (the same number as the measurement light generating units 11a, 11b, and 11c included in the transmission unit 1, three in the illustrated example) and a type identifying unit 302. These units 301a, 301b, 301c, and 302 are realized, for example, by the CPU 31 executing a program P stored in the storage device 34. The storage device 34 also stores reflectance data D, which is data used to identify the type of the object At.

[0069] The first reflectance specifying unit 301a specifies a first reflectance Ra, which is the reflectance of the object At at the first wavelength λa, based on the detection result from the first photodetector 22a. The first reflectance Ra is a value specified from the ratio of the intensities of the first measurement light beam La before and after reflection from the object At, and can be acquired by an appropriate method based on the detection signal obtained from the first photodetector 22a. For example, the first reflectance specifying unit 301a may specify the first reflectance Ra based on a beat signal included in the detection signal of a composite wave of the first measurement light beam La and the reference light beam L0a (for example, from the amplitude of the beat signal), or may specify the first reflectance Ra from the ratio of the detection signal from the first photodetector 22a to the detection signal of the reference light beam L0a.

[0070] Similarly, the second reflectance specifying unit 301b specifies a second reflectance Rb, which is the reflectance of the object At at the second wavelength λb, based on the detection result from the second photodetector 22b. The second reflectance Rb is a value specified from the ratio of the intensities of the second measurement light beam Lb before and after reflection from the object At, and can be obtained by an appropriate method based on the detection signal obtained from the second photodetector 22b.

[0071] Similarly, the third reflectance specifying unit 301c specifies a third reflectance Rc, which is the reflectance of the object At at the third wavelength λc, based on the detection result of the third photodetector 22c. The third reflectance Rc is a value specified from the ratio of the intensities of the third measurement light beam Lc before and after reflection from the object At, and can be obtained by an appropriate method based on the detection signal obtained from the third photodetector 22c.

[0072] As described above, in the detection device 100, the light guiding unit 13 includes the spatial phase modulator 131 implemented using the grating light valve 5. Light incident on the grating light valve 5 is reflected at an angle (scanning angle) corresponding to the displacement of the ribbons 52. Strictly speaking, this angle varies slightly depending on the wavelength of the incident light. Therefore, when the aggregate light beam L is incident on the grating light valve 5, the measurement light beams La, Lb, and Lc included in the aggregate light beam L are guided in directions slightly offset from one another. Therefore, for an object At located at a certain position, the time t1 when the reflected light of the first measurement light beam La is acquired by the first photodetector 22a, the time t2 when the reflected light of the second measurement light beam Lb is acquired by the second photodetector 22b, and the time t3 when the reflected light of the third measurement light beam Lc is acquired by the third photodetector 22c are slightly offset from one another. In other words, simply linking the reflectances derived from the detection results obtained by the photodetectors 22a, 22b, and 22c at the same time as reflectances relating to the same object At (same position) may result in an inaccurate link. Therefore, it is preferable to take into account the difference in scanning angle resulting from the difference in wavelengths λa, λb, and λc, and link the reflectances Ra, Rb, and Rc derived from the detection results obtained by the photodetectors 22a, 22b, and 22c at mutually different times t1, t2, and t3 as reflectances Ra, Rb, and Rc relating to the same object At. This allows the reflectances Ra, Rb, and Rc for the same object At to be correctly linked.

[0073] The type identification unit 302 identifies the type of the object At based on the multiple reflectances Ra, Rb, and Rc of the object At identified by each of the reflectance identification units 301 a, 301 b, and 301 c. Specifically, the type identification unit 302 identifies the type of the object At by determining whether the object At is of candidate type Ti using the multiple reflectances Ra, Rb, and Rc of the object At and the multiple reflectances Tia, Tib, and Tic of the candidate type Ti described in the reflectance data D.

[0074] The reflectance data D will now be described with reference to Fig. 9. In the reflectance data D, for each of one or more pre-selected candidate types Ti (i = 1, 2, ...), the reflectances Tia, Tib, and Tic at wavelengths λa, λb, and λc of multiple measurement light beams La, Lb, and Lc are described, for example, in table format.

[0075] For example, suppose three candidate types T1, T2, and T3 are "plant," "concrete," and "asphalt." In this case, the reflectance data D is linked to "first candidate type T1: plant" and describes the reflectance T1a of the plant at a first wavelength λa (532 nm in the figure as an example), the reflectance T1b of the plant at a second wavelength λb (1064 nm in the figure as an example), and the reflectance T1c of the plant at a third wavelength λc (1550 nm in the figure as an example). Similarly, the reflectance T2a of the concrete at a first wavelength λa, the reflectance T2b of the concrete at a second wavelength λb, and the reflectance T2c of the concrete at a third wavelength λc are linked to "second candidate type T2: concrete." Similarly, the reflectance T3a of asphalt at the first wavelength λa, the reflectance T3b of asphalt at the second wavelength λb, and the reflectance T3c of asphalt at the third wavelength λc are described in association with "third candidate type T3: asphalt."

[0076] The number and types of candidate types Ti can be determined arbitrarily, but it is preferable to select as candidate types Ti types that are expected to have a high need for identification in consideration of the usage environment of the detection device 100, etc. For example, if the detection device 100 is a LiDAR mounted on an automobile, it is preferable to select as candidate types Ti at least one of types that are likely to appear in the field of view while driving, such as asphalt, concrete, plants, cloth, soil, skin, brick, stone, water, etc.

[0077] The type identification unit 302 compares the reflectances Ra, Rb, Rc of the object At with the reflectances Tia, Tib, Tic of the candidate type Ti for each wavelength λa, λb, λc, and determines whether the object At is of the candidate type Ti.

[0078] For example, whether the object At is a "first candidate type T1: plant" can be determined as follows. That is, to perform this determination, the type identification unit 302 calculates the difference d1a between the reflectance Ra of the object At at a first wavelength λa and the reflectance T1a of the plant at the first wavelength λa. Similarly, the type identification unit 302 calculates the difference d1b between the reflectance Rb of the object At at a second wavelength λb and the reflectance T1b of the plant at the second wavelength λb. Furthermore, the type identification unit 302 calculates the difference d1c between the reflectance Rc of the object At at a third wavelength λc and the reflectance T1c of the plant at the third wavelength λc. Then, the sum or average of all the differences d1a, d1b, and d1c is obtained as a representative difference value d1. The smaller this representative difference value d1, the higher the degree of match between the reflectance characteristics of the object At and the reflectance characteristics of the "first candidate type T1: plant." In other words, the object At is more likely to be a "first candidate type T1: plant." Therefore, the type identification unit 302, for example, compares the representative difference value d1 with a predetermined threshold, and if the representative difference value d1 is equal to or less than the predetermined threshold, determines that the degree of match is sufficiently high, that is, that the object At is a "first candidate type T1: plant." On the other hand, if the representative difference value d1 is greater than the threshold, determines that the degree of match is not sufficiently high, that is, that the object At is not a "first candidate type T1: plant."

[0079] In this way, by using multiple reflectances Ra, Rb, and Rc at different wavelengths λa, λb, and λc to determine whether the object At is of the candidate type Ti, the possibility of an erroneous determination can be sufficiently reduced, and the type of the object At can be identified with sufficient accuracy. For example, if the determination is made using only the reflectance Ra of the first wavelength λa, and the reflectance Ra shown in FIG. 9 is obtained, there is a risk that the object At, which is actually a "plant," will be erroneously determined to be "asphalt." However, by making the determination while also taking into account the reflectance Rb of the second wavelength λb, the possibility of the object At being erroneously determined to be "asphalt" is reduced. Needless to say, by making the determination while also taking into account the reflectance Rc of the third wavelength λc, the possibility of an erroneous determination can be further reduced.

[0080] For example, when a candidate type Ti is found that is determined to have a sufficiently high degree of match, the type identification unit 302 may determine that the object At is of the candidate type Ti and terminate the identification process. Alternatively, the type identification unit 302 may perform a determination for all of one or more candidate types Ti (i = 1, 2, ...) whose reflectances are described in the reflectance data D, and determine that the candidate type Ti with the highest degree of match is the type of the object At. Furthermore, when it is determined that the degree of match is not sufficiently high for all of the one or more candidate types Ti (i = 1, 2, ...) whose reflectances are stored in the reflectance data D, the type identification unit 302 may determine that the object At is of a type other than the candidate type Ti (i = 1, 2, ...), or may determine that some kind of error has occurred.

[0081] <4. Operation flow> An example of the flow of operations of the detection device 100 will be described with reference to Fig. 10. Fig. 10 is a diagram showing an example of the flow of operations of the detection device 100.

[0082] The operation of the detection device 100 includes a transmission step (step S101: steps S1 to S3) of transmitting light to the scanning area A, a reception step (step S102: steps S4 to S5) of receiving light reflected from an object At in the scanning area A, and a calculation step (step S103: steps S6 to S7) of performing calculations based on the detection results obtained in the reception step. The transmission step and the reception step are carried out by the control unit 3 controlling the transmission unit 1 and the reception unit 2. Each of these steps will be described in detail below.

[0083] Step S1: Measurement light generation process First, the first measurement light generator 11a performs wavelength sweep on a light beam with a first wavelength λa emitted from the light source to generate and emit a first measurement light beam La whose wavelength changes continuously from the first wavelength λa (step S1a). In parallel with this, the second measurement light generator 11b performs wavelength sweep on a light beam with a second wavelength λb emitted from the light source to generate and emit a second measurement light beam Lb whose wavelength changes continuously from the second wavelength λb (step S1b). In parallel with this, the third measurement light generator 11c performs wavelength sweep on a light beam with a third wavelength λc emitted from the light source to generate and emit a third measurement light beam Lc whose wavelength changes continuously from the third wavelength λc (step S1c).

[0084] Step S2: Merging process Next, the converging unit 12 converges the measurement light beams La, Lb, and Lc emitted from the measurement light generating units 11a, 11b, and 11c to form a collective light beam L, and causes the collective light beam L to enter the light guiding unit 13.

[0085] Step S3: Light induction process Next, the light guiding unit 13 guides the aggregate light beam L including the multiple measurement light beams La, Lb, and Lc to scan the scanning area A. Specifically, the spatial phase modulation element 131 guides the aggregate light beam L in a direction (first direction Ax) perpendicular to its extending direction (second direction Ay), thereby scanning the two-dimensional scanning area A with the aggregate light beam L.

[0086] Step S4: Branching process Next, the splitter 21 splits the collective light beam L that is irradiated onto the scanning area A and reflected by the object At therein into a plurality of beams.

[0087] Step S5: Light detection process Next, a first aggregate light beam L1, which is one of the split aggregate light beams L, is incident on a first photodetector 22a after a first filter 23a attenuates frequency bands other than the frequency band corresponding to the first measurement light beam La. The first photodetector 22a receives the light beam that has passed through the first filter 23a, i.e., the first measurement light beam La reflected by the scanning area A, and detects its intensity (step S5a). Concurrently, a second aggregate light beam L2, which is another of the split aggregate light beams L, is incident on a second photodetector 22b after a second filter 23b attenuates frequency bands other than the frequency band corresponding to the second measurement light beam Lb. The second photodetector 22b receives the light beam that has passed through the second filter 23b, i.e., the second measurement light beam Lb reflected by the scanning area A, and detects its intensity (step S5b). In parallel with this, the third aggregate light beam L3, which is one of the remaining split aggregate light beams L, is incident on the third photodetector 22c after frequency bands other than the frequency band corresponding to the third measurement light beam Lc are attenuated by the third filter 23c. The third photodetector 22c receives the light beam that has passed through the third filter 23c, i.e., the third measurement light beam Lc reflected by the scanning area A, and detects its intensity (step S5c).

[0088] Step S6: Measurement data calculation process For example, in step S5a, the control unit 3 calculates various measurement data (e.g., the distance to the object At, the position of the object At, etc.) regarding the object At in the scanning area A based on the detection results obtained by the first photodetector 22a.

[0089] Step S7: Type Identification Process Furthermore, the control unit 3 identifies the type of the target object At based on the detection results obtained by the multiple photodetectors 22a, 22b, and 22c in steps S5a, S5b, and S5c.

[0090] Step S71 Specifically, first, the first reflectance specifying unit 301a specifies a first reflectance Ra, which is the reflectance of the object At at a first wavelength λa, based on the detection result of the first photodetector 22a. Further, the second reflectance specifying unit 301b specifies a second reflectance Rb, which is the reflectance of the object At at a second wavelength λb, based on the detection result of the second photodetector 22b. Further, the third reflectance specifying unit 301c specifies a third reflectance Rc, which is the reflectance of the object At at a third wavelength λc, based on the detection result of the third photodetector 22c.

[0091] Step S72 Next, the type identification unit 302 identifies the type of the object At based on the multiple reflectances Ra, Rb, and Rc of the object At identified in step S71. Specifically, for example, the type identification unit 302 compares the reflectances Ra, Rb, and Rc of the object At with the reflectances Tia, Tib, and Tic of the candidate type Ti described in the reflectance data D for each wavelength λa, λb, and λc, and determines whether the object At is of the candidate type Ti, thereby identifying the type of the object At.

[0092] <5. Effects> The detection device 100 according to the embodiment includes a transmitter 1 that transmits light to a scanning area A and a receiver 2 that receives light reflected by an object At in the scanning area A. The transmitter 1 includes a first measurement light generator 11a that generates a first measurement light beam La whose wavelength changes continuously from a first wavelength λa, a second measurement light generator 11b that generates a second measurement light beam Lb whose wavelength changes continuously from a second wavelength λb different from the first wavelength λa, a third measurement light generator 11c that generates a third measurement light beam Lc whose wavelength changes continuously from a third wavelength λc different from the first wavelength λa and the second wavelength λb, and a light guide 13 that guides a collective light beam L, which is light including the first measurement light beam La, the second measurement light beam Lb, and the third measurement light beam Lc, to scan the scanning area A.

[0093] According to this configuration, the transmitter 1 includes multiple measurement light generators 11a, 11b, and 11c, each generating measurement light beams La, Lb, and Lc having different wavelength ranges, and thus can acquire reflected light from the scanning area A scanned by the multiple measurement light beams La, Lb, and Lc having different wavelength ranges in parallel. This allows for additional functions to be added in addition to the basic function of detecting an object and measuring the distance to the object, thereby achieving even higher functionality. For example, by acquiring detection results for the same object At using multiple measurement light beams La, Lb, and Lc having different wavelength ranges, it is possible to derive information other than the distance to the object At (e.g., the type of object At).

[0094] Furthermore, in the detection device 100 according to the above embodiment, the transmitter 1 includes a converging unit 12 that converges the first measurement light beam La, the second measurement light beam Lb, and the third measurement light beam Lc to form an aggregate light beam L and causes the aggregate light beam L to enter the light guiding unit 13. The receiver 2 includes a branching unit 21 that branches the aggregate light beam L reflected by the object At, a first filter 23a that is arranged on the optical path of one aggregate light beam L1 of the branched aggregate light beams L and attenuates frequency bands other than the frequency band corresponding to the first measurement light beam La and passes the frequency band corresponding to the first measurement light beam La, and a second filter 23b that is arranged on the optical path of another aggregate light beam L2 of the branched aggregate light beams L and attenuates frequency bands other than the frequency band corresponding to the second measurement light beam Lb and passes the frequency band corresponding to the second measurement light beam Lb. a third filter 23c arranged on the optical path of another aggregate light beam L3 of the multiple branched aggregate light beams L, which attenuates frequency bands other than the frequency band corresponding to the third measurement light beam Lc and passes the frequency band corresponding to the third measurement light beam Lc; a first photodetector 22a which detects the light beam that has passed through the first filter 23a; a second photodetector 22b which detects the light beam that has passed through the second filter 23b; and a third photodetector 22c which detects the light beam that has passed through the third filter 23c.

[0095] According to this simple configuration, it is possible to acquire, in parallel, reflected light beams resulting from scanning of the scanning area A by a plurality of measurement light beams La, Lb, and Lc having mutually different wavelength ranges.

[0096] Furthermore, the detection device 100 according to the above embodiment includes a first reflectance specifying unit 301a that specifies a first reflectance Ra, which is the reflectance of the object At at a first wavelength λa, based on the detection result of the first photodetector 22a; a second reflectance specifying unit 301b that specifies a second reflectance Rb, which is the reflectance of the object At at a second wavelength λb, based on the detection result of the second photodetector 22b; a third reflectance specifying unit 301c that specifies a third reflectance Rc, which is the reflectance of the object At at a third wavelength λc, based on the detection result of the third photodetector 22c; and a type identifying unit 302 that identifies the type of the object At based on the first reflectance Ra, the second reflectance Rb, and the third reflectance Rc.

[0097] According to this configuration, the type of the object At is identified based on the reflectances Ra, Rb, and Rc of the object At at each of multiple different wavelengths λa, λb, and λc, so that the type of the object At can be identified with sufficient accuracy.

[0098] Furthermore, the detection device 100 according to the above embodiment includes a storage unit (storage device 34) that stores reflectance data D describing, for each of one or more candidate types Ti (i=1, 2, ...), the reflectance Tia of the candidate type Ti at a first wavelength λa, the reflectance Tib of the candidate type Ti at a second wavelength λb, and the reflectance Tic of the candidate type Ti at a third wavelength λc. The type identification unit 302 then compares the reflectances Ra, Rb, and Rc of the object At with the reflectances Tia, Tib, and Tic of the candidate type T for each of the first wavelength λa, the second wavelength λb, and the third wavelength λc, to determine whether the object At is of the candidate type T.

[0099] This configuration makes it possible to easily identify the type of the object At. For example, by narrowing down the candidate types Ti to types that are expected to be highly necessary to be identified in consideration of the usage environment of the detection device 100, it is possible to ensure that the type of the object At can be identified to a necessary and sufficient degree, while also sufficiently reducing the processing burden associated with type identification.

[0100] The detection method according to the above embodiment also includes a transmitting step (step S101) of transmitting light (light beam) to a scanning area A, and a receiving step (step S102) of receiving the light beam reflected by an object At in the scanning area A. The transmitting step also includes a measurement light generating step (step S1) of generating a first measurement light beam La whose wavelength changes continuously from a first wavelength λa, a second measurement light beam Lb whose wavelength changes continuously from a second wavelength λb different from the first wavelength λa, and a third measurement light beam Lc whose wavelength changes continuously from a third wavelength λc different from the first wavelength λa and the second wavelength λb, a combining step (step S2) of combining the first measurement light beam La, the second measurement light beam Lb, and the third measurement light beam Lc to form an aggregate light beam L, and a light guiding step (step S3) of guiding the aggregate light beam L to scan the scanning area A. The receiving process also includes a branching process (step S4) for branching the collective light beam L reflected by the object At, and a light detection process (step S5) for detecting one collective light beam L1 of the branched collective light beams L after attenuating frequency bands other than the frequency band corresponding to the first measurement light beam La, detecting another collective light beam L2 of the branched collective light beams L after attenuating frequency bands other than the frequency band corresponding to the second measurement light beam Lb, and detecting another collective light beam L3 of the branched collective light beams L after attenuating frequency bands other than the frequency band corresponding to the third measurement light beam Lc.

[0101] According to this configuration, it is possible to acquire reflected light in parallel when the scanning area A is scanned with a plurality of measurement light beams La, Lb, and Lc having different wavelength ranges.

[0102] <6. Variations> <6-1. First modified example> In the detection device 100 according to the above embodiment, the light guiding unit 13 guides the aggregate light beam L including the multiple measurement light beams La, Lb, and Lc to scan the scanning area A, but it is not necessary to scan the scanning area A with the aggregate light beam L. For example, the control unit 3 may select one of the multiple measurement light generators 11a, 11b, and 11c and cause only the selected measurement light generator to generate a measurement light beam, and the light guiding unit 13 may guide only the generated one type of measurement light beam to scan the scanning area A. In other words, the light guiding unit 13 may selectively guide one of the multiple measurement light beams La, Lb, and Lc to scan the scanning area A.

[0103] In this way, in the detection device 100, the transmitter 1 includes multiple measurement light generators 11a, 11b, and 11c that generate measurement light beams La, Lb, and Lc having different wavelength ranges, and the detection device 100 can selectively acquire reflected light beams obtained by scanning the scanning area A with the measurement light beams La, Lb, and Lc having different wavelength ranges. Therefore, for example, by switching the measurement light beams La, Lb, and Lc to be used in response to changes in the usage environment of the detection device 100, the status inside the device, and the like (e.g., weather changes, occurrence of a malfunction), the detection device 100 can flexibly respond to such changes. In this way, it is possible to provide additional functions in addition to the basic function of detecting an object and measuring the distance to the object, thereby achieving even more advanced functionality.

[0104] In this modification, the receiver 2 may include one photodetector, and the measurement light beam reflected by the object At may be directly incident on the one photodetector. That is, the receiver 2 may omit the branching unit 21, the second photodetector 22b, the third photodetector 22c, and the filters 23a, 23b, and 23c.

[0105] <6-2. Second modified example> In the above embodiment, the control unit 3 may further include an output unit that outputs the calculated measurement data, the identification result of the type of the object At, etc. Specifically, the output unit may generate an output image representing the scanning area A based on the calculated measurement data, and display the output image on the display unit 36. In this case, the output unit may display each object (i.e., an object detected as the object At) appearing in the output image in a different manner depending on its type. Specifically, for example, each object may be displayed in a different color according to the identified type, or may be displayed with a different pattern according to the identified type. Furthermore, for example, an object identified as a specific type may be displayed in a manner that highlights the object (for example, by adding a mark).

[0106] <6-3.Third modified example> The transmitter 1 in the above embodiment includes three measurement light generating units 11a, 11b, and 11c that generate measurement light beams in different wavelength ranges, but the transmitter 1 may also include two, four, or more measurement light generating units that generate measurement light beams in different wavelength ranges.

[0107] Furthermore, when the transmitter 1 includes N measurement light generators (where "N" is an integer equal to or greater than 2) that generate measurement light beams in different wavelength ranges, the type identification unit 302 can identify the type of the object At using M reflectivities (i.e., using the reflectivities of the object At at M different wavelengths) identified from the detection results of M measurement light beams (where "M" is an integer equal to or greater than 2 and equal to or less than N) among the N measurement light beams generated by the N measurement light generators. By performing identification using at least two reflectivities, the accuracy of identification can be sufficiently ensured, and the accuracy of identification further increases as the number of reflectivities used increases. Conversely, the processing load related to identification decreases as the number of reflectivities used decreases.

[0108] <6-4. Fourth Variation> In the transmitter 1 according to the above embodiment, the light guide 13 can be realized using various configurations capable of guiding a light beam. For example, the light guide 13 may include a MEMS (Micro Electro Mechanical Systems) mirror configured to be rotatable around two orthogonal axes. Furthermore, the light guide 13 may include various spatial phase modulation elements 131 other than the grating light valve 5, such as a planar light valve (PLV). Specifically, the planar light valve has, for example, a configuration in which a plurality of grating elements (e.g., grating elements having a circular shape in a planar view) are arranged in a matrix on a substrate. By displacing each of the grating elements relative to the substrate, the phase of the incident light beam is modulated and the light beam is guided.

[0109] However, when a light beam whose wavelength changes continuously (i.e., a wavelength-swept light beam) is guided using a MEMS mirror, the MEMS mirror continues to move while the wavelength of the light beam is being changed, which can cause problems such as the waveform of the light beam projected onto the scanning area A being distorted or the direction in which the light beam is guided (scanning angle) being shifted. In contrast, when a light beam whose wavelength changes continuously is guided using a spatial phase modulator 131 such as a grating light valve 5 or a planar light valve, for example, the grating elements (ribbons 52 in the case of a grating light valve 5) of the spatial phase modulator 131 can be kept stationary while one wavelength sweep cycle is being performed so that the scan angle of the light beam does not change. The displacement mode of the grating elements can be changed (i.e., the scan angle can be changed) when one wavelength sweep cycle ends and the next wavelength sweep cycle begins. Therefore, the above-mentioned problems are unlikely to occur. That is, by providing the light guiding unit 13 with the spatial phase modulator 131, the measurement light beams La, Lb, and Lc, whose wavelengths change continuously, can be appropriately guided to the scanning area A. Furthermore, the spatial phase modulator 131 can operate the grating elements at high speed (for example, in the case of the grating light valve 5, the ribbons 52 can be operated at a high speed of 100 kHz or more). Therefore, it is possible to instantaneously change the displacement mode of the grating elements, which makes it possible to appropriately guide the measurement light beams La, Lb, and Lc to the scanning area A while keeping the time required to scan the scanning area A sufficiently short. For the above reasons, when light beams whose wavelengths change continuously are used as the measurement light beams La, Lb, and Lc, it is particularly preferable that the light guiding unit 13 be configured to include the spatial phase modulator 131.

[0110] <6-5. Fifth Variation> In the above embodiment, the reflectance data D describes the reflectances Tia, Tib, and Tic for each wavelength λa, λb, and λc for each candidate type Ti in table format, but the reflectance data D is not limited to this configuration. For example, the reflectance data D may store a function representing the reflectance characteristics of each candidate type Ti, and use this function to identify the reflectances Tia, Tib, and Tic for each wavelength λa, λb, and λc. With this configuration, regardless of the wavelength of the measurement light beam used, the reflectance of each candidate type Ti at that wavelength can be identified.

[0111] <6-6. Other variations> The optical configuration of the detection device 100 according to the above embodiment is merely an example, and can be modified as appropriate.

[0112] For example, the projection optical system of the transmitter 1 may have a function of increasing the reflection angle of the collective light beam L by the spatial phase modulator 131 to widen the guidance range (scanning angle range) of the collective light beam L. This function can be realized, for example, by forming an image of the collective light beam L at a position before the scanning area A as in the above embodiment, or can also be realized by combining multiple lenses.

[0113] The transmitter 1 may further include a polarizing beam splitter and a quarter-wave plate. Specifically, for example, the collective light beam L emitted from the lens 103 may be bent at a right angle by the polarizing beam splitter, passed through a quarter-wave plate, and then incident on the spatial phase modulator 131. The collective light beam L reflected by the spatial phase modulator 131 may then pass through a quarter-wave plate again before being incident on the polarizing beam splitter. In this case, the collective light beam L rotates by a quarter wavelength upon passing through the quarter-wave plate for the first time, then enters the spatial phase modulator 131 and is reflected there. Then, it rotates by a further quarter wavelength upon passing through the quarter-wave plate for the second time, and then enters the polarizing beam splitter. Since the collective light beam L incident on the polarizing beam splitter has been rotated by a half wavelength upon passing through the two quarter-wave plates, it passes through the polarizing beam splitter and heads toward the projection optical system.

[0114] Furthermore, each of the photodetectors 22a, 22b, and 22c of the receiving unit 2 may be configured to include, for example, a two-dimensional photodetector array in which the photodetectors 221 are arranged two-dimensionally.

[0115] Furthermore, in the receiving unit 2, for example, a microlens array in which a plurality of microlenses are arranged one-dimensionally may be provided between each filter 23a, 23b, 23c and each photodetector 22a, 22b, 22c so that each microlens corresponds to each photodetector 221, and each microlens may be configured to image each measurement light beam La, Lb, Lc incident thereon onto each corresponding photodetector 221.

[0116] Furthermore, in the receiving unit 2, for example, a light combining element array in which a plurality of light combining elements are arranged one-dimensionally may be provided between each of the filters 23a, 23b, 23c and each of the photodetectors 22a, 22b, 22c (or between the microlenses and each of the photodetectors 22a, 22b, 22c if a microlens is provided), so that each light combining element corresponds to each of the photodetectors 221, and each of the measurement light beams La, Lb, Lc incident thereon and the corresponding reference light beams L0a, L0b, L0c may be incident on each light combining element. In such a configuration, each of the measurement light beams La, Lb, Lc and each of the corresponding reference light beams L0a, L0b, L0c are superimposed by each light combining element and then incident on each of the photodetectors 221. Therefore, each photodetector 221 of each of the photodetectors 22a, 22b, 22c detects a composite wave of each of the measurement light beams La, Lb, Lc and the corresponding reference light beams L0a, L0b, L0c.

[0117] The functions and operations of the control unit 3 of the detection device 100 according to the above embodiment are merely examples, and can be changed as appropriate.

[0118] For example, in the above embodiment, the measurement data acquired by the control unit 3 may be either the distance to the object At or the position of the object At, or various other data (for example, the speed of the object At) may be acquired as measurement data. Furthermore, the method by which the control unit 3 acquires the measurement data does not necessarily have to be the FMCW method, and may be, for example, the ToF (Time of Flight) method, the AMCW method, or the like.

[0119] Although the detection device 100 and the detection method have been described in detail above, the above description is merely illustrative in all respects and is not intended to be limiting. It is understood that countless variations not illustrated can be envisioned without departing from the scope of this disclosure. Furthermore, the configurations described in the above embodiments and variations can be combined or omitted as appropriate, provided they are not mutually inconsistent. [Explanation of symbols]

[0120] 100 Detection device 1. Transmitter 11a First measurement light generation section 11b Second measurement light generation section 11c Third measurement light generation section 12 Confluence 13 Light guiding section 131 Spatial Phase Modulator 2. Receiving section 21 Branch 22a First photodetector 22b Second photodetector 22c Third photodetector 23a First filter 23b Second filter 23c Third filter 3. Control Unit 301a 1st reflectance identification section 301b 2nd reflectance specific part 301c 3rd reflectance specific part 302 Type Identification Unit D Reflectance Data La First measurement light (light beam) Lb Second measurement light (light beam) Lc Third measurement light (light beam) L, L1, L2, L3 Collective light (light beam)

Claims

1. a transmitter that transmits light to the scanning area; a receiving unit that receives light reflected from an object in the scanning area; A control unit; Equipped with The transmission unit: a first measurement light generating unit that generates a first measurement light whose wavelength changes continuously from a first wavelength; a second measurement light generating unit that generates second measurement light whose wavelength changes continuously from a second wavelength different from the first wavelength; a light guide unit that guides light including at least one of the first measurement light and the second measurement light to scan the scanning area; Equipped with The receiving unit: a first photodetector that detects the first measurement light reflected by the object; a second photodetector that detects the second measurement light reflected by the object; Equipped with The control unit calculating a distance to the object based on at least one of the detection result by the first photodetector and the detection result by the second photodetector, and identifying the type of the object based on the detection result by the first photodetector and the detection result by the second photodetector; Detection device.

2. 2. The detection device according to claim 1, The transmission unit: a converging unit that converges the first measurement light and the second measurement light to form converged light and causes the converged light to be incident on the light guiding unit; Equipped with The receiving unit: a branching unit that branches the collective light reflected by the object; a first filter disposed on an optical path of one of the plurality of split collective beams, the first filter attenuating frequency bands other than the frequency band corresponding to the first measurement beam and passing the frequency band corresponding to the first measurement beam; a second filter disposed on an optical path of another one of the plurality of split collective beams, the second filter attenuating frequency bands other than the frequency band corresponding to the second measurement beam and passing the frequency band corresponding to the second measurement beam; Equipped with the first photodetector detects light that has passed through the first filter; the second photodetector detects light that has passed through the second filter; Detection device.

3. The detection device according to claim 2, The control unit a first reflectance specifying unit that specifies a first reflectance, which is a reflectance of the object at the first wavelength, based on a detection result by the first photodetector; a second reflectance specifying unit that specifies a second reflectance, which is a reflectance of the object at the second wavelength, based on a detection result by the second photodetector; a type identification unit that identifies a type of the object based on the first reflectance and the second reflectance; A detection device comprising:

4. The detection device according to claim 3, The control unit a storage unit that stores, for each of one or more candidate types, reflectance data that describes the reflectance of the candidate type at the first wavelength and the reflectance of the candidate type at the second wavelength; Equipped with The type identification unit comparing the reflectance of the object with the reflectance of the candidate type for each of the first wavelength and the second wavelength to determine whether the object is of the candidate type; Detection device.

5. 5. The detection device according to claim 1, The light guide portion is a spatial phase modulation element having a plurality of grating elements, and modulating the phase of incident light by displacing each of the plurality of grating elements to guide the light; A detection device comprising:

6. transmitting light to a scanning region; receiving light reflected from an object in the scanning area; a calculation step of performing calculation processing based on the detection result acquired in the receiving step; Equipped with The transmitting step a measurement light generating step of generating a first measurement light whose wavelength changes continuously from a first wavelength and generating a second measurement light whose wavelength changes continuously from a second wavelength different from the first wavelength; a combining step of combining the first measurement light and the second measurement light to form a collective light; a light guiding step of guiding the collected light to scan the scanning area; Equipped with The receiving step a branching step of branching the collected light reflected by the object; a light detection step of detecting one of the plurality of split collective light beams after attenuating a frequency band other than the frequency band corresponding to the first measurement light, and detecting another of the plurality of split collective light beams after attenuating a frequency band other than the frequency band corresponding to the second measurement light; Equipped with The calculation step a measurement data calculation step of calculating a distance to the object based on at least one of the detection results of the first measurement light and the second measurement light; a type identification step of identifying the type of the object based on the detection results of the first measurement light and the second measurement light; A detection method comprising:

Images