JP2023162680A - Detection device and detection method - Google Patents

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

The present disclosure relates to a detection device and a detection method that perform detection using light.

There are various detection technologies using light, one of which is LiDAR (Light Detection And Ranging) technology (for example, Patent Document 1). With LiDAR technology, for example, light is emitted toward an object, and the light reflected by the object is detected to determine the distance to the object.

JP 2021-184067 Publication

LiDAR technology has been rapidly developing in recent years, and technological development is also progressing to make LiDAR devices smaller and lower in cost. On the other hand, in addition to the basic function of detecting an object and measuring the distance to the object, it is expected that a technology will emerge that will allow LiDAR devices to have additional functions to make them more sophisticated. .

The present disclosure aims to provide a technology that can realize even higher functionality in a detection device or detection method that performs detection using light.

A first aspect is a detection device that includes a transmitter that transmits light to a scanning area, and a receiver that receives light reflected by an object in the scan area, and the transmitter includes: a first measurement light generation unit that generates a first measurement light whose wavelength changes continuously from a first wavelength; and a second measurement light generation unit that generates a second measurement light whose wavelength changes continuously from a second wavelength different from the first wavelength. and a light guide section that guides light including at least one of the first measurement light and the second measurement light to scan the scanning area.

A second aspect is the detection device according to the first aspect, in which the transmission section merges the first measurement light and the second measurement light to form collective light, and transmits the collective light to the light guiding section. a convergence section for making the light incident on the target object, and a branching section for branching the collective light reflected by the target object, and a branching section on the optical path of one of the plurality of branched collective lights. a first filter arranged to attenuate frequency bands other than the frequency band corresponding to the first measurement light and pass a frequency band corresponding to the first measurement light; a second beam disposed on the optical path of another one of the collective lights, attenuating frequency bands other than the frequency band corresponding to the second measurement light, and passing a frequency band corresponding to the second measurement light; The device includes a filter, a first photodetector that detects light that has passed through the first filter, and a second photodetector that detects light that has passed through the second filter.

A third aspect is the detection device according to the second aspect, in which a first reflectance, which is a reflectance of the object at the first wavelength, is determined based on a detection result by the first photodetector. a first reflectance specifying unit that specifies; and a second reflectance specifying unit that specifies a second reflectance that is a reflectance of the object at the second wavelength based on a detection result of the second photodetector. and a type identification unit that identifies the type of the object based on the first reflectance and the second reflectance.

A fourth aspect is the detection device according to the third aspect, wherein for each of the one or more candidate types, the reflectance of the candidate type at the first wavelength and the reflection of the candidate type at the second wavelength are determined. a storage unit that stores reflectance data describing a reflectance of the target object and a reflectance of the candidate type for each of the first wavelength and the second wavelength. It is determined whether the target object is of the candidate type.

A fifth aspect is the detection device according to any one of the first to fourth aspects, in which the light guiding section has a plurality of grating elements, and by displacing each of the plurality of grating elements. A spatial phase modulation element is provided that modulates the phase of incident light and guides the light.

A sixth aspect is a detection method, comprising a transmitting step of transmitting light to a scanning region, and a receiving step of receiving light reflected by an object in the scanning region, and the transmitting step includes: A measurement light generation step of generating first measurement light whose wavelength changes continuously from a first wavelength, and generating second measurement light whose wavelength changes continuously from a second wavelength different from the first wavelength. a merging step of merging the first measurement light and the second measurement light into collective light; and a light guiding step of guiding the collective light to scan the scanning area, the receiving step comprising: , a branching step of branching the aggregated light reflected by the object, and attenuating frequency bands other than the frequency band corresponding to the first measurement light in one of the plurality of branched aggregated lights. a light detection step of attenuating frequency bands other than the frequency band corresponding to the second measurement light and then detecting another one of the plurality of branched aggregated lights; and.

According to the first aspect, since the transmitting unit includes a plurality of measurement light generation units each generating measurement light in different wavelength ranges, reflected light obtained by scanning a scanning area with a plurality of measurement lights having different wavelength ranges. can be obtained in parallel or alternatively. Therefore, in addition to the basic function of detecting an object and measuring the distance to the object, it is possible to provide an additional function, thereby achieving even higher functionality. For example, by acquiring detection results for the same object using multiple measurement beams with different wavelength ranges, it is possible to derive information other than the distance to the object (for example, the type of the object). . Further, for example, by switching the measuring light to be used in accordance with changes in the usage environment of the detection device, the internal situation of the device, etc., it is possible to flexibly respond to the changes.

According to the second aspect, with a simple configuration, reflected light obtained by scanning a scanning area with a plurality of measurement lights having different wavelength ranges can be acquired in parallel.

According to the third aspect, since the type of the target object is identified based on the reflectance of the target object at each of a plurality of mutually different wavelengths, the type of the target object can be identified with sufficient accuracy.

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

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

According to the sixth aspect, reflected light obtained by scanning a scanning area with a plurality of measurement lights having different wavelength ranges can be acquired in parallel.

FIG. 1 is a block diagram showing a schematic configuration of a detection device according to an embodiment. FIG. 2 is a block diagram showing the hardware configuration of a control unit. FIG. 2 is a plan view schematically showing a portion of a grating light valve. FIG. 2 is a side view schematically showing a grating light valve. FIG. 3 is a schematic diagram for explaining the operation of a grating light valve. FIG. 3 schematically shows the optical system of the detection device as seen along the direction in which the line beam is guided; FIG. 3 is a diagram schematically showing the optical system of the detection device as seen along the extending direction of a line beam. FIG. 2 is a block diagram showing a configuration related to type identification. FIG. 3 is a diagram schematically showing an example of reflectance characteristics. It is a figure showing an example of the flow of operation of a sensing device.

Embodiments will be described below with reference to the accompanying drawings. Note that the components described in this embodiment are merely examples, and the scope of the present disclosure is not intended to be limited thereto. Further, in the drawings, the dimensions or numbers of each part may be exaggerated or simplified as necessary for easy understanding.

Expressions that indicate relative or absolute positional relationships (e.g., "in one direction," "along one direction," "parallel," "perpendicular," "centered," "concentric," "coaxial," etc.) Unless otherwise specified, not only strictly represents their positional relationship, but also represents a state in which they are relatively displaced in terms of angle or distance within a range that allows tolerance or equivalent functionality to be obtained. Furthermore, unless otherwise specified, expressions indicating equal conditions (e.g., "same," "equal," "homogeneous," etc.) do not only refer to quantitatively strictly equal conditions, but also to tolerances or the same condition. It also represents a state in which there is a difference in the degree of function obtained. Furthermore, unless otherwise specified, expressions that indicate shapes (e.g., "circular shape," "square shape," "cylindrical shape," etc.) do not only strictly represent the shape geometrically; It represents the shape of the range in which the effect can be obtained, and may have, for example, unevenness or chamfering. In addition, expressions such as "comprising," "comprising," "equipment," "containing," and "having" a component are not exclusive expressions that exclude the presence of other components. In addition, the expression "at least one of A, B, and C" includes "only A," "only B," "only C," "any two of A, B, and C," and " All of A, B and C" are included.

<1. Schematic configuration of detection device>
A 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 a schematic configuration of a detection device 100.

The detection device 100 is a device (so-called LiDAR device) that performs detection and distance measurement using light, and includes a transmitting unit 1 that transmits light (light beam) to an area (scanning area) A around the detection device 100. , a receiver 2 that receives light transmitted from a transmitter 1 to a scanning area A and reflected by an object At in the scan area A, and a controller 3 that controls each of these units 1 and 2.

(Transmitter 1)
The transmitter 1 includes a plurality of (three in the illustrated example) measurement light generators 11a, 11b, and 11c, a merging section 12, and a light guiding section 13.

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 suitably used in LiDAR devices (that is, wavelengths that can satisfy requirements such as being less affected by sunlight and ensuring safety for human eyes) are 532 nm, 850 nm, and 905 nm. , 1064 nm, 1550 nm, etc. Any of these wavelengths may be selected as the first wavelength λa.

The second measurement light generation unit 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 as appropriate; for example, a wavelength suitably used in the LiDAR device and different from the first wavelength λa may be selected as the second wavelength λb. .

The third measurement light generation unit 11c generates a third measurement light beam Lc whose wavelength changes continuously from a third wavelength λc which is different from both the first wavelength λa and the second wavelength λb. The third wavelength λc can also be selected as appropriate. For example, a wavelength suitably used in a LiDAR device that is different from the first wavelength λa and the second wavelength λb may be selected as the third wavelength λc. May be selected.

The merging section 12 merges the measurement light beams La, Lb, and Lc emitted from the measurement light generation sections 11a, 11b, and 11c to form a collective light beam L, and makes the collective light beam L enter the light guiding section 13. let

The light guiding unit 13 guides the collective light beam L that has entered thereto to scan the scanning area A. Specifically, the light guide section 13 is configured to include, 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, modulates the phase of an incident light beam by displacing each of the plurality of grating elements, and guides the light beam.

(Receiving section 2)
The receiving section 2 includes a branching section 21 and a plurality of (the same number as the measurement light generating sections 11a, 11b, 11c included in the transmitting section 1, three in the illustrated example) photodetectors 22a, 22b, 22c, Filters 23a, 23b, and 23c are provided between the branching portion 21 and each of the photodetectors 22a, 22b, and 22c.

The branching unit 21 transmits the collective light beam L that is irradiated onto the scanning area A and reflected by the object At located there, to the same number of photodetectors 22a, 22b, and 22c (that is, the measurement light generation unit included in the transmitting unit 1). The number of parts is the same as that of parts 11a, 11b, and 11c, and is branched into three parts in the example shown.

The first filter 23a is arranged on the optical path of one of the branched collective light beams L (first collective light beam L1), and attenuates frequency bands other than the frequency band corresponding to the first measurement light beam La. , a frequency band corresponding to the first measuring light beam La is passed and made incident on the first photodetector 22a. On the other hand, the first photodetector 22a detects the incident light (that is, 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 there.

Similarly, the second filter 23b is disposed on the optical path of another one of the branched collective light beams L (second collective light beam L2), and is configured to filter frequencies other than the frequency band corresponding to the second measurement light beam Lb. While attenuating the band, a frequency band corresponding to the second measurement light beam Lb is passed and made incident on the second photodetector 22b. On the other hand, the second photodetector 22b detects the incident light (that is, 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 present therein.

Similarly, the third filter 23c is disposed on the optical path of the remaining one of the branched collective light beams L (third collective light beam L3), and is arranged in a frequency band other than the frequency band corresponding to the third measurement light beam Lc. At the same time, a frequency band corresponding to the third measurement light beam Lc is allowed to pass and is made incident on the third photodetector 22c. On the other hand, the third photodetector 22c detects the incident light (that is, 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 there.

(Control unit 3)
The control unit 3 is an element that controls the operation of each unit 1 and 2 included in the detection device 100 and performs various arithmetic processing, and is configured by, for example, a general computer having an electric circuit or a microcomputer. be done.

Specifically, the control unit 3 includes, for example, a processor such as a CPU (Central Processor Unit) 31 as a central processing unit responsible for data processing, or an FPGA (Field Programmable Gate Array), as shown in FIG. Furthermore, the control unit 3 includes a ROM (Read Only Memory) 32 in which basic programs and the like are stored, a RAM (Random Access Memory) 33 used as a work area when the CPU 31 performs predetermined processing (data processing), and a flash memory. , a storage device 34 constituted by a nonvolatile storage device such as a hard disk device, and a bus line 35 that interconnects these devices.

The storage device 34 stores a program P that specifies the process to be executed by the control unit 3, and when the CPU 31 executes this program P, the control unit 3 executes the process specified by the program P. I can do it. However, part 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.

Further, the control unit 3 may be further connected to a display unit 36 that displays various information, an input unit 37 that receives input operations from an operator, and the like. As the display section 36, various display devices such as a liquid crystal display can be used. Further, as the input unit 37, a keyboard, a mouse, a touch panel, a microphone, etc. can be used.

<2. Configuration of detection device>
Next, a specific configuration example of the detection device 100 will be described. In the following, first, a configuration example of the spatial phase modulation element 131 included in the light guide section 13 will be described, and then an example of the overall configuration of the detection device 100 including the spatial phase modulation element 131 will be described.

<2-1. Spatial phase modulation element>
As described above, the spatial phase modulation element 131 has a plurality of grating elements, and guides the incident light beam by displacing each of the plurality of grating elements to perform phase modulation on the incident 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 phased array.

The grating light valve 5 will be explained with reference to FIGS. 3 to 5. FIG. 3 is a plan view schematically showing a part of the grating light valve 5. As shown in FIG. FIG. 4 is a side view schematically showing the grating light valve 5. As shown in FIG. FIG. 5 is a diagram for explaining the operation of the grating light valve 5. As shown in FIG.

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

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, for example, by a metal film formed on the upper surface of the substrate 511 (the main surface on the side where the ribbon 52 is provided).

Each of the plurality of ribbons 52 plays a role as a grating element in the grating light valve 5. The plurality of ribbons 52 are arranged in a line on one main surface of the substrate 511. Each ribbon 52 has an elongated shape in plan view, and is oriented such that its elongate direction is orthogonal to the arrangement direction. 3 to 5, for convenience of explanation, a coordinate system is shown in which the arrangement direction of the plurality of ribbons 52 is "Gx" and the longitudinal direction of each ribbon 52 is "Gy". .

Each ribbon 52 has flexibility, and is connected to the main surface of the substrate 511 at both end portions in the longitudinal direction while providing a gap between the ribbon 52 and the substrate 511 at the center portion in the longitudinal direction. Furthermore, each ribbon 52 includes a reflective surface 521 provided on its upper surface (a surface opposite to the surface facing the substrate 511) that regularly reflects the light beam. The reflective surface 521 is realized, for example, by a thin film of metal (for example, aluminum) formed on the upper surface of the ribbon 52. Further, each ribbon 52 includes an electrode (ribbon electrode) 522. The ribbon electrode 522 is realized, for example, by a thin metal film for realizing the reflective surface 521. Needless to say, in addition to the thin film for realizing the reflective surface 521, a thin film for realizing the ribbon electrode 522, etc. may be provided.

As described above, each ribbon 52 has flexibility. 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 due to electrostatic force and is displaced in the normal direction of the substrate 511 (indicated by a dashed line in FIG. 4). state). Further, when the potential difference between the electrodes 512 and 522 disappears, the electrostatic force disappears, and the ribbon 52 elastically returns to its unflexed state (the state shown by the solid line in FIG. 4). A potential difference according to a signal from the control unit 3 is applied between the electrodes 512 and 522, and each ribbon 52 is displaced relative to the substrate 511 by an amount corresponding to the applied potential difference. That is, the displacement amount ΔG of the ribbon 52 with respect to the substrate 511 is controlled by a signal from the control section 3.

In the grating light valve 5, the displacement amount ΔG of each of the plurality of ribbons 52 is controlled by a signal from the control unit 3, so that the plurality of ribbons 52 can form various modes (patterns). For example, the grating light valve 5 can form a pattern in which the displacement amounts ΔG of the plurality of ribbons 52 are equally zero (first mode M1). At this time, the grating light valve 5 functions as a mirror, and the light incident on the grating light valve 5 is specularly reflected. For example, the grating light valve 5 can also form a blaze pattern in which the displacement amount ΔG of the plurality of 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 has an arbitrary blaze period (displacement period) B and an arbitrary blaze angle (sawtooth shape) in addition to the second mode M2 and the third mode M3 illustrated in the figure. It is possible to form a blaze pattern with an angle formed by the inclined surface of the substrate 511 with respect to the substrate 511. When the plurality of 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 corresponding to the blaze period B. Therefore, by successively changing the blaze period B of the blaze pattern formed by the plurality of ribbons 52 (circulating 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. It becomes possible. In this way, by successively changing the direction in which the light beam is emitted, the light beam can be guided to scan the scanning area A.

<2-2. Overall configuration of 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 the light beam so as to spread it in a predetermined direction, and applies the light beam to a linear area extending one-dimensionally in the scanning area A. (A light beam that spreads in a predetermined direction and irradiates a linear region extending in the predetermined direction is also referred to as a "line beam" hereinafter). On the other hand, the transmitter 1 guides the line beam in a direction that intersects with the direction in which the line beam extends (in this case, a direction that intersects perpendicularly with the direction in which it extends). As a result, a two-dimensional scanning area A (that is, a two-dimensional scanning area A defined by the direction in which the line beam is guided and the direction in which the line beam extends) is scanned by the light beam (so-called 1 dimensional line scan method). FIG. 6 is a diagram schematically showing the optical system of the detection device 100 as seen along the direction Ax in which the line beam is guided (hereinafter also referred to as "first direction"), and FIG. FIG. 2 is a diagram schematically showing the optical system of the detection device 100 as seen along the current direction (hereinafter also referred to as “second direction”) Ay.

Each of the plurality of measurement light generating units 11a, 11b, and 11c includes, for example, a light source including 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) in a wavelength sweep section, thereby creating a measurement light beam La, whose wavelength (frequency) continuously changes. Lb and Lc are generated. The width of change in wavelength (sweep width) may be appropriately defined, and may be, for example, about several nm.

As described above, each of the measurement light generation units 11a, 11b, and 11c generates and emits measurement light beams La, Lb, and Lc whose wavelengths change continuously from mutually different wavelengths λa, λb, and λc. That is, the light source included in the first measurement light generation section 11a emits a light beam with a first wavelength λa, and the first measurement light generation section 11a emits a light beam with a first wavelength λa emitted from the light source. By performing a wavelength sweep on the first measurement light beam La, a first measurement light beam La whose wavelength changes continuously from the first wavelength λa is generated. Similarly, the light source included in the second measurement light generation section 11b emits a light beam of a second wavelength λb, and the second measurement light generation section 11b emits a light beam of a second wavelength λb emitted from the light source. By performing wavelength sweeping on the beam, a second measurement light beam Lb whose wavelength changes continuously from the second wavelength λb is generated. Similarly, the light source included in the third measurement light generation section 11c emits a light beam with a third wavelength λc, and the third measurement light generation section 11c emits light with a third wavelength λc emitted from the light source. By performing wavelength sweeping on the beam, a third measurement light beam Lc whose wavelength changes continuously from the third wavelength λc is generated.

When viewed along the first direction Ax (FIG. 6), the measurement light beams La, Lb, Lc emitted from the measurement light generation units 11a, 11b, 11c are collimated in the second direction Ay by the cylindrical lens 101. be done. A beam splitter 102 is provided after the cylindrical lens 101, and the beam splitter 102 splits the collimated measurement light beams La, Lb, Lc into the measurement light beams La, Lb, Lc and the reference light beam L0a. , L0b, and L0c. Each reference light beam L0a, L0b, L0c is a light beam whose wavelength changes continuously like each measurement light beam La, Lb, Lc, and is sent to the receiver 2 and used to obtain a beat signal. .

Subsequently, the plurality of measurement light beams La, Lb, and Lc are combined (that is, guided on the same optical axis) at a confluence section 12 that includes, for example, a mirror, to form a collective light beam L. It is said that In the illustrated example, the measurement light beams La, Lb, and Lc are combined from the second direction Ay, but the measurement light beams La, Lb, and Lc may be combined from the first direction Ax. .

Thereafter, the collective light beam L is focused by the lens 103 onto the center of the spatial phase modulation element 131 in the second direction Ay. As described above, the spatial phase modulation element 131 is realized using the grating light valve 5, and the grating light valve 5 has the arrangement direction Gx of the ribbons 52 parallel to the first direction Ax, and the extension of each ribbon 52. It is arranged so that the direction Gy is parallel to the second direction Ay. Therefore, the collective light beam L is focused by the lens 103 in the extending direction Gy of each ribbon 52, and is imaged at the center of the extending direction Gy. The displacement amount ΔG of each ribbon 52 is controlled with particularly high precision in the central region of the ribbon 52 in the extending direction Gy, and by being configured such that the collective light beam L is incident on the central region, the spatial It becomes possible to control the angle (scanning angle) of the collective light beam L reflected from the phase modulation element 131 with sufficiently high accuracy.

The collective light beam L reflected by the spatial phase modulation element 131 enters the lens 104, is collimated by the lens 104 in the second direction Ay, and then is imaged by the lens 105 in the second direction Ay. An imaging point on 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 a group of lenses 104 and 105 shapes the collective light beam L so as to spread it in the second direction Ay, and irradiates the scanning area A with it.

On the other hand, when viewed along the second direction Ay (FIG. 7), each measurement light beam La, Lb, Lc emitted from each measurement light generation section 11a, 11b, 11c enters the cylindrical lens 101, but the cylindrical The lens 101 has no power in the first direction Ax. Therefore, each measurement light beam La, Lb, Lc emitted from each measurement light generation unit 11a, 11b, 11c travels without being refracted in the first direction Ax by the cylindrical lens 101.

Subsequently, each of the measurement light beams La, Lb, and Lc is combined at a merging section 12 to form a collective light beam L, and then enters a lens 103, collimated by the lens 103 in the first direction Ax, and then released into space. The light is incident on the phase modulation element 131. That is, the collective light beam L is incident on a strip-shaped region extending long and thin along the arrangement direction Gx of each ribbon 52 of the grating light valve 5 that realizes the spatial phase modulation element 131. As described above, in the grating light valve 5, the displacement amount ΔG of each of the plurality of ribbons 52 is controlled by the signal from the control unit 3, whereby phase modulation is performed on the collective light beam L, and the collective light beam L is reflected at an angle (scanning angle) according to the displacement mode (mode) of the plurality of ribbons 52. In FIG. 7, a collective light beam L reflected at two different angles is also shown.

The collective light beam L reflected by the spatial phase modulation element 131 enters the lens 104, is imaged by the lens 104 in the first direction Ax, and is then collimated by the lens 105 in the first direction Ax. In other words, the projection optical system including a group of lenses 104 and 105 shapes the collective light beam L emitted from the spatial phase modulation element 131 so as to narrow it in the first direction Ax, and forms it into the scanning area A. irradiate.

As described above, the scanning area A includes a collective light beam L that is expanded in the second direction Ay and narrowed in the first direction Ax (that is, a collective light beam that is shaped into a line beam extending in the second direction Ay). L) is irradiated. On the other hand, the spatial phase modulation element 131 successively changes the angle at which the collective light beam L is reflected. As a result, the collective light beam L is guided in a direction (first direction Ax) perpendicular to its extending direction (second direction Ay), and a two-dimensional scanning area A defined by both directions Ax and Ay is guided by the collective light beam L. Scanned by beam L. The size of the scanning area A, that is, 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 as a line beam and the guidance range (scanning) of the collective light beam L by the light guide unit 13. angle range).

Continuing on, looking along the second direction Ay (FIG. 7), the collective light beam L that is irradiated onto the scanning area A and reflected by the object At present there is received through the camera lens 201 etc., and the beam The light is branched into a plurality of pieces (the same number as the photodetectors 22a, 22b, 22c included in the receiving unit 2, three in the illustrated example) by a branching unit 21 that includes a splitter and the like. In the illustrated example, the collective light beam L is branched into a plurality of parts in the first direction Ax, but the collective light beam L may be branched into a plurality of parts in the second direction Ay.

A first collective light beam L1, which is one of the plurality of branched collective 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. For example, it is composed of a bandpass filter. Therefore, the first collective light beam L1 including the plurality of measurement light beams La, Lb, and Lc is attenuated in the first filter 23a in frequency bands other than the frequency band corresponding to the first measurement light beam La, and then 1 enters the photodetector 22a. That is, the light beam that has passed through the first filter 23a, that is, the first measurement light beam La that has been irradiated onto the scanning area A and reflected there, is incident on the first photodetector 22a.

Similarly, the second collective light beam L2, which is another one of the plurality of branched collective 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 allows the frequency band corresponding to the second measurement light beam Lb to pass. For example, it is composed of a bandpass filter. Therefore, the second collective light beam L2 including the plurality of measurement light beams La, Lb, and Lc is attenuated in a frequency band other than the frequency band corresponding to the second measurement light beam Lb in the second filter 23b, and then 2 enters the photodetector 22b. That is, the light beam that has passed through the second filter 23b, that is, the second measurement light beam Lb that has been irradiated onto the scanning area A and reflected there, is incident on the second photodetector 22b.

Similarly, the third collective light beam L3, which is the remaining one of the plurality of branched collective 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 allows the frequency band corresponding to the third measurement light beam Lc to pass. For example, it is composed of a bandpass filter. Therefore, the third collective light beam L3 including the plurality of measurement light beams La, Lb, and Lc is attenuated in a frequency band other than the frequency band corresponding to the third measurement light beam Lc in the third filter 23c. 3 enters the photodetector 22c. That is, the light beam that has passed through the third filter 23c, that is, the third measurement light beam Lc that has been irradiated onto the scanning area A and reflected there, is incident on the third photodetector 22c.

When viewed along the first direction Ax (FIG. 6), each photodetector 22a, 22b, 22c is, for example, a so-called one-dimensional array in which a plurality of photodetectors (light receiving elements) 221 are arranged in one dimension (one row). It is configured to include a photodetector array, and the photodetectors 221 are arranged so that the arrangement direction thereof is 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, which in turn is transmitted through the filters 23a, 23b, 23c. The measurement light beams La, Lb, and Lc after passing through are also similar line beams. That is, each measurement light beam La, Lb, Lc, which is a line beam extending in the second direction Ay, is incident on a plurality of photodetectors 221 arranged in the second direction Ay in each photodetector 22a, 22b, 22c. do. Therefore, each photodetector 221 detects the intensity of light at each position in the second direction Ay in each measurement light beam La, Lb, Lc.

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

For example, the control unit 3 performs various measurements regarding the object At in the scanning area A based on the detection result of at least one photodetector selected from the plurality of photodetectors 22a, 22b, and 22c. Data (for example, distance to object At, position of object At, etc.) is calculated. Specifically, for example, 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 controls the detection signal of the first measurement light beam La obtained by the selected at least one photodetector (for example, the first photodetector 22a) and the detection signal of the first measurement light beam La that is irradiated onto the scanning area A. The detection signal of the reference light beam L0a branched from the previous first measurement light beam La is superimposed to obtain a detection signal of a composite wave of both light beams La and L0a. This composite wave includes a beat signal generated by interference between the first measurement light beam La and its reference light beam L0a, and the control unit 3 specifies the frequency difference between the two light beams La and L0a based on this beat signal. , calculates the distance to the target object At from the frequency difference. For example, the control unit 3 may also control the control unit 3 based on the scanning angle (the guiding position of the collective light beam L by the light guiding unit 13) when the first measuring light beam La reflected by the target object At is projected onto the scanning area A. , specify the position of the object At in the first direction Ax. For example, the control unit 3 identifies the position of the object At in the second direction Ay based on the array position of the photodetector 221 that detected the first measurement light beam La reflected by the object At.

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

<3. Identification of type>
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 from the plurality of 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 characteristic" here refers to the reflectance for each wavelength (aspect of change in reflectance with respect to wavelength). As an example, FIG. 9 schematically shows the reflectance characteristics of "plants" (T1), the reflectance characteristics of "concrete" (T2), and the reflectance characteristics of "asphalt" (T3). has been done. As illustrated in this figure, the reflectance characteristics are unique to each type of object and differ depending on the type. Therefore, the detection device 100 specifies the reflectances Ra, Rb, and Rc of the target object At at each of the plurality of wavelengths λa, λb, and λc from the detection results of the plurality of photodetectors 22a, 22b, and 22c, and The type of the target object At is identified from the reflectance characteristics estimated from the plurality of reflectances Ra, Rb, and Rc.

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 a configuration related to type identification.

As a configuration related to type identification, the control unit 3 includes a plurality of (the same number as the measurement light generating units 11a, 11b, 11c included in the transmitting unit 1, three in the illustrated example) reflectance specifying units 301a, 301b. , 301c, and a type identification section 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 . The storage device 34 also stores reflectance data D, which is data used to identify the type of object At.

The first reflectance specifying unit 301a specifies the first reflectance Ra, which is the reflectance of the object At at the first wavelength λa, based on the detection result by the first photodetector 22a. The first reflectance Ra is a value specified from the ratio of the intensity of the first measurement light beam La before and after being reflected by the target object At, and is determined as appropriate based on the detection signal obtained from the first photodetector 22a. It can be obtained in this way. For example, the first reflectance specifying unit 301a determines the first reflectance based on the beat signal included in the detection signal of the composite wave of the first measurement light beam La and its reference light beam L0a (for example, from the amplitude amount of the beat signal). The reflectance Ra may be specified, or the first reflectance Ra may be specified from the ratio of the detection signal of the first photodetector 22a and the detection signal of the reference light beam L0a.

Similarly, the second reflectance identifying unit 301b identifies the second reflectance Rb, which is the reflectance of the object At at the second wavelength λb, based on the detection result by the second photodetector 22b. The second reflectance Rb is a value specified from the ratio of the intensity of the second measuring light beam Lb before and after being reflected by the target object At, and is a value determined as appropriate based on the detection signal obtained from the second photodetector 22b. It can be obtained in this way.

Similarly, the third reflectance specifying unit 301c specifies the third reflectance Rc, which is the reflectance of the object At at the third wavelength λc, based on the detection result by the third photodetector 22c. The third reflectance Rc is a value specified from the ratio of the intensity of the third measurement light beam Lc before and after being reflected by the target object At, and is determined as appropriate based on the detection signal obtained from the third photodetector 22c. It can be obtained in this way.

As described above, in the detection device 100, the light guide section 13 is configured to include the spatial phase modulation element 131 realized using the grating light valve 5. The light incident on the grating light valve 5 is reflected at an angle (scanning angle) depending on the displacement mode of the plurality of ribbons 52. Strictly speaking, the angle varies slightly depending on the wavelength of the incident light. It will be different. Therefore, when the collective light beam L is incident on the grating light valve 5, the measurement light beams La, Lb, and Lc included in the collective light beam L are guided in directions slightly shifted from each other. Become. Therefore, regarding the object At at a certain position, at time t1 when the reflected light of the first measurement light beam La is acquired by the first photodetector 22a, and at time t1 when the reflected light of the second measurement light beam Lb is acquired by the second photodetector The time t2 acquired by the third 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 shifted from each other. In other words, if we simply link the reflectances derived from the detection results obtained by each of the photodetectors 22a, 22b, and 22c at the same time as the reflectances related to the same object At (same position), , there is a risk that the correct linkage may not be made. Therefore, taking into account the shift in scanning angle resulting from the difference between the wavelengths λa, λb, and λc, the detection results obtained by the photodetectors 22a, 22b, and 22c at mutually shifted times t1, t2, and t3 are derived. It is preferable to link the obtained reflectances Ra, Rb, and Rc to each other as reflectances Ra, Rb, and Rc related to the same object At. As a result, the reflectances Ra, Rb, and Rc for the same object At are correctly linked.

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

Here, the reflectance data D will be explained with reference to FIG. 9. The reflectance data D includes data at each wavelength λa, λb, λc of a plurality of measurement light beams La, Lb, Lc for each of one or more candidate types Ti (i=1, 2, . . . ) selected in advance. The reflectances Tia, Tib, and Tic are described, for example, in a table format.

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

The number and type of candidate types Ti can be arbitrarily defined, but in view of the usage environment of the detection device 100, etc., it is possible to select a type that is assumed to have a high need for identification as the candidate type Ti. preferable. For example, if the detection device 100 is a LiDAR installed in a car, the type that is likely to appear in the field of view while driving, for example, asphalt, concrete, plants, cloth, soil, skin, brick, stone, water, etc. It is preferable that at least one of them is selected as the candidate type Ti.

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 corresponds to the target object At. It is determined whether the candidate type is Ti.

For example, it can be determined whether the target object At is "first candidate type T1: plant" as follows. That is, in making this determination, the type identification unit 302 calculates the difference d1a between the reflectance Ra of the object At at the first wavelength λa and the reflectance T1a of the plant at the first wavelength λa. Similarly, a difference d1b between the reflectance Rb of the object At at the second wavelength λb and the reflectance T1b of the plant at the second wavelength λb is calculated. Furthermore, a difference d1c between the reflectance Rc of the object At at the third wavelength λc and the reflectance T1c of the plant at the third wavelength λc is calculated. Then, the sum, average value, etc. of all the differences d1a, d1b, and d1c are obtained as the representative difference value d1. The smaller this representative difference value d1 is, the higher the degree of coincidence between the reflectance characteristics of the target object At and the reflectance characteristics of the "first candidate type T1: plants". It can be said that there is a high possibility that it is a plant. Therefore, for example, the type identification unit 302 compares the representative difference value d1 with a predetermined threshold, and if the representative difference value d1 is less than or equal to the predetermined threshold, the degree of matching is sufficiently high, that is, the object At is It is determined that the type is "first candidate type T1: plant". On the other hand, when the representative difference value d1 is larger than the threshold value, it is determined that the degree of matching is not sufficiently high, that is, the target object At is not "first candidate type T1: plant".

In this way, by using multiple reflectances Ra, Rb, and Rc at different wavelengths λa, λb, and λc to determine whether or not the object At is of the candidate type Ti, an erroneous determination may occur. The type of object At can be identified with sufficient accuracy. For example, when determination is made using only the reflectance Ra of the first wavelength λa, if the reflectance Ra illustrated in FIG. 9 is obtained, the object At that is actually a "plant" will be There is a risk that it may be mistakenly determined to be "asphalt." However, by performing the determination by further taking into account the reflectance Rb of the second wavelength λb, the possibility that the object At is erroneously determined to be "asphalt" is reduced. Needless to say, by further taking into account the reflectance Rc of the third wavelength λc, the possibility of erroneous determination is further reduced.

For example, when a candidate type Ti for which the matching degree is determined to be sufficiently high is found, the type identification unit 302 determines that the object At is of the candidate type Ti, and ends the process related to identification. Good too. Alternatively, the type identification unit 302 determines all of the one or more candidate types Ti (i=1, 2, . . . ) whose reflectances are described in the reflectance data D, and selects the candidate type with the highest degree of matching. Ti may be determined to be the type of object At. Further, if it is determined that the degree of matching is not sufficiently high for all of the one or more candidate types Ti (i=1, 2, . . . ) whose reflectances are held in the reflectance data D, the type identification unit 302 It may be determined that the object At is of a type other than the candidate type Ti (i=1, 2, . . . ), or it may be determined that some kind of error has occurred.

<4. Operation flow>
An example of the flow of the operation 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 operation of the detection device 100.

The operation of the detection device 100 includes a transmission process (step S101: step S1 to step S3) of transmitting light to the scanning area A, and a reception process (step S102: Step S4 to Step S5), and a calculation step (Step S103: Step S6 to Step S7) for performing calculation processing based on the detection result obtained in the reception step. The transmitting step and the receiving step proceed as the control section 3 controls the transmitting section 1 and the receiving section 2. Each of these steps will be specifically explained below.

Step S1: Measurement light generation step First, the first measurement light generation section 11a performs wavelength sweeping on the light beam of the first wavelength λa emitted from the light source, so that the wavelength changes continuously from the first wavelength λa. A first measurement light beam La is generated and emitted (step S1a). In parallel with this, the second measurement light generation section 11b performs wavelength sweeping on the light beam of the second wavelength λb emitted from the light source, so that the second measurement light generating section 11b performs a wavelength sweep on the light beam of the second wavelength λb emitted from the light source. A measurement light beam Lb is generated and emitted (step S1b). In parallel with these, the third measurement light generation unit 11c performs wavelength sweeping on the light beam of the third wavelength λc emitted from the light source, so that the third measurement light generation unit 11c performs a wavelength sweep on the light beam of the third wavelength λc emitted from the light source, so that A measurement light beam Lc is generated and emitted (step S1c).

Step S2: Merging Step Next, the merging section 12 merges the measurement light beams La, Lb, and Lc emitted from the measurement light generation sections 11a, 11b, and 11c to form a collective light beam L. L is made incident on the light guide section 13.

Step S3: Light guiding step Subsequently, the light guiding section 13 guides the collective light beam L including the plurality of measurement light beams La, Lb, and Lc to scan the scanning area A. Specifically, the spatial phase modulation element 131 guides the collective light beam L in a direction (first direction Ax) perpendicular to its extending direction (second direction Ay), thereby controlling the two-dimensional scanning area A. is scanned by a collective light beam L.

Step S4: Branching step Subsequently, the branching unit 21 branches the collective light beam L that has been irradiated onto the scanning area A and reflected by the object At present therein into a plurality of beams.

Step S5: Photodetection step Next, the first collective light beam L1, which is one of the plurality of branched collective light beams L, is detected in the first filter 23a in a frequency band other than the frequency band corresponding to the first measurement light beam La. After the frequency band of the light is attenuated, the light enters the first photodetector 22a. The first photodetector 22a receives the light beam that has passed through the first filter 23a, that is, the first measurement light beam La reflected from the scanning area A, and detects its intensity (step S5a). In parallel with this, the second collective light beam L2, which is another one of the plurality of branched collective light beams L, is filtered in a frequency band other than that corresponding to the second measurement light beam Lb in the second filter 23b. After having its frequency band attenuated, it enters the second photodetector 22b. The second photodetector 22b receives the light beam that has passed through the second filter 23b, that is, the second measurement light beam Lb reflected by the scanning area A, and detects its intensity (step S5b). In parallel with these, the third collective light beam L3, which is the remaining one of the plurality of branched collective light beams L, is filtered in a frequency band other than the third measuring light beam Lc in the third filter 23c. After having its frequency band attenuated, it enters the third photodetector 22c. The third photodetector 22c receives the light beam that has passed through the third filter 23c, that is, the third measurement light beam Lc reflected from the scanning area A, and detects its intensity (step S5c).

Step S6: Measurement data calculation step For example, in step S5a, the control unit 3 calculates various measurement data (for example, distance to the target object At, position of the target object At, etc.).

Step S7: Type identification step Further, the control unit 3 identifies the type of the target object At based on the detection results obtained by the plurality of photodetectors 22a, 22b, and 22c in steps S5a, 5b, and 5c.

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

Step S72
Subsequently, the type identification unit 302 identifies the type of the object At based on the plurality of reflectances Ra, Rb, and Rc of the object At identified in step S71. Specifically, for example, the type identification unit 302 determines, for each wavelength λa, λb, λc, the reflectance Ra, Rb, Rc of the object At, and the reflectance Tia, Tia, of the candidate type Ti described in the reflectance data D. Tib and Tic are compared to determine whether or not the target object At is of the candidate type Ti, thereby identifying the type of the target object At.

<5. Effect>
The detection device 100 according to the above 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 transmitting unit 1 includes a first measuring light generating unit 11a that generates a first measuring light beam La whose wavelength changes continuously from a first wavelength λa, and a first measuring light beam La that continuously changes from a second wavelength λb different from the first wavelength λa. a second measuring light beam Lb that generates a second measuring light beam Lb whose wavelength changes continuously; and a third measuring light beam whose wavelength changes continuously from a third wavelength λc different from the first wavelength λa and the second wavelength λb. A third measurement light generation section 11c that generates a measurement light beam Lc, and a collective light beam L that is light including a first measurement light beam La, a second measurement light beam Lb, and a third measurement light beam Lc are guided. and a light guiding section 13 that scans the scanning area A.

According to this configuration, the transmitter 1 includes a plurality of measurement light generators 11a, 11b, and 11c that each generate measurement light beams La, Lb, and Lc in different wavelength ranges. Reflected light from the measurement light beams La, Lb, and Lc that scanned the scanning area A can be acquired in parallel. Therefore, in addition to the basic function of detecting an object and measuring the distance to the object, it is possible to provide an additional function, thereby achieving even higher functionality. For example, information other than the distance to the target At (for example, information other than the distance to the target At ) can be derived.

Further, in the detection device 100 according to the above embodiment, the transmitter 1 merges the first measurement light beam La, the second measurement light beam Lb, and the third measurement light beam Lc to form a collective light beam L. A merging section 12 is provided that causes the collective light beam L to enter a light guide section 13 . The receiving unit 2 is arranged on the optical path of a branching unit 21 that branches the collective light beam L reflected by the object At, and one of the collective light beams L1 among the plurality of branched collective light beams L. , a first filter 23a that attenuates frequency bands other than the frequency band corresponding to the first measurement light beam La and passes a frequency band corresponding to the first measurement light beam La, and a plurality of branched collective light beams. is arranged on the optical path of another one of the collective light beams L2 of L, attenuates frequency bands other than the frequency band corresponding to the second measurement light beam Lb, and also attenuates the frequency band corresponding to the second measurement light beam Lb. The second filter 23b is disposed on the optical path of another collective light beam L3 among the plurality of branched collective light beams L, and is arranged on the optical path of another collective light beam L3 of the plurality of branched collective light beams L, and transmits a frequency band other than that corresponding to the third measurement light beam Lc. a third filter 23c that attenuates the frequency band and passes a frequency band corresponding to the third measurement light beam Lc; a first photodetector 22a that detects the light beam that has passed through the first filter 23a; It includes a second photodetector 22b that detects the light beam that has passed through the filter 23b, and a third photodetector 22c that detects the light beam that has passed through the third filter 23c.

According to this configuration, reflected light obtained by scanning the scanning area A with a plurality of measurement light beams La, Lb, and Lc having different wavelength ranges can be acquired in parallel with a simple configuration.

The detection device 100 according to the embodiment described above also includes a first reflectance Ra that is a reflectance of the object At at the first wavelength λa based on the detection result of the first photodetector 22a. a second reflectance specifying section 301b that specifies a second reflectance Rb, which is the reflectance of the object At at the second wavelength λb, based on the detection result of the reflectance specifying section 301a and the second photodetector 22b; , a third reflectance specifying unit 301c that specifies a third reflectance Rc, which is the reflectance of the target object At at the third wavelength λc, based on the detection result by the third photodetector 22c; and a first reflectance Ra. , a type identification unit 302 that identifies the type of the object At based on the second reflectance Rb and the third reflectance Rc.

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 a plurality of mutually different wavelengths λa, λb, and λc. Can be identified with accuracy.

Furthermore, for each of one or more candidate types Ti (i=1, 2, . . . ), the detection device 100 according to the embodiment described above also determines the reflectance Tia of the candidate type Ti at the first wavelength λa and the second It includes a storage unit (storage device 34) that stores reflectance data D that describes the reflectance Tib of the candidate type Ti at the wavelength λb and the reflectance Tic of the candidate type Ti at the third wavelength λc. Then, the type identification unit 302 determines the reflectances Ra, Rb, Rc of the object At, the reflectances Tia, Tib, Tib, and Tic is compared to determine whether the target object At is of the candidate type T or not.

According to this configuration, the type of object At can be easily identified. For example, by narrowing down the candidate types Ti to types that are assumed to have a high need for identification in consideration of the usage environment of the detection device 100, etc., it is possible to identify the type of the target object At to a necessary and sufficient degree. It is possible to sufficiently reduce the burden of processing related to type identification while ensuring that

Further, the detection method according to the above embodiment includes a transmission step (step S101) of transmitting light (light beam) to the scanning area A, and a reception step of receiving the light beam reflected by the object At in the scanning area A. step (step S102). Here, the transmitting step generates a first measurement light beam La whose wavelength continuously changes from a first wavelength λa, and a first measurement light beam La whose wavelength continuously changes from a second wavelength λb different from the first wavelength λa. a measurement light generation step of generating two measurement light beams Lb and, together with these, 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; (Step S1), a merging step (Step S2) of merging the first measurement light beam La, the second measurement light beam Lb, and the third measurement light beam Lc into a collective light beam L; and a light guiding step (step S3) of guiding the light to scan the scanning area A. Further, the receiving step includes a branching step (step S4) of branching the collective light beam L reflected by the target object At, and a branching step (step S4) of branching the collective light beam L reflected by the target object At, and transmitting one collective light beam L1 of the plurality of branched collective light beams L to the first collective light beam L1. The frequency bands other than the frequency band corresponding to the measurement light beam La are attenuated and then detected, and another one of the plurality of branched collective light beams L, L2, is converted into a second measurement light beam Lb. Attenuating and detecting frequency bands other than the frequency band corresponding to A photodetection step (step S5) is provided, in which frequency bands other than the frequency band to be detected are attenuated and then detected.

According to this configuration, reflected light obtained by scanning the scanning area A with a plurality of measurement light beams La, Lb, and Lc having different wavelength ranges can be acquired in parallel.

<6. Modified example>
<6-1. First modification>
In the detection device 100 according to the above embodiment, the light guide section 13 guides the collective light beam L including the plurality of measurement light beams La, Lb, and Lc to scan the scanning area A. There is no need to scan the scanning area A with the light beam L. For example, the control section 3 selects one of the plurality of measurement light generation sections 11a, 11b, and 11c and causes only the selected measurement light generation section to generate the measurement light beam, and the light guide section 13 The scanning area A may be scanned by guiding only one type of generated measurement light beam. That is, the light guide section 13 may selectively guide any one of the plurality of measurement light beams La, Lb, and Lc to scan the scanning area A.

In this way, in the detection device 100 in which the transmitting unit 1 includes a plurality of measurement light generation units 11a, 11b, and 11c that generate measurement light beams La, Lb, and Lc in different wavelength ranges, the wavelength ranges are mutually different. It is also possible to alternatively acquire reflected light obtained by scanning the scanning area A with a plurality of different measuring light beams La, Lb, and Lc. Therefore, for example, by switching the measurement light beams La, Lb, and Lc to be used according to changes in the usage environment of the detection device 100, the internal situation of the device, etc. (for example, changes in the weather, occurrence of a failure), the changes can be made. be able to respond flexibly. 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 higher functionality.

In this modification, the receiving section 2 is equipped with one photodetector, and is configured such that the measurement light beam reflected by the object At is directly incident on the one photodetector. Good too. That is, in the receiving section 2, the branching section 21, the second photodetector 22b, the third photodetector 22c, and each of the filters 23a, 23b, and 23c may be omitted.

<6-2. Second modification>
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 target object At, and the like. Specifically, for example, 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. At this time, the output unit may display each object appearing in the output image (that is, the object detected as the target object At) in a different manner depending on its type. Specifically, for example, each object may be displayed in different colors for each identified type, or may be displayed in a different pattern for each identified type. For example, an object identified as a specific type may be displayed in a manner that emphasizes the object (for example, by adding a mark).

<6-3. Third modification>
The transmitter 1 according to the embodiment described above includes three measurement light generators 11a, 11b, and 11c that generate measurement light beams in different wavelength ranges. It may be provided with two, or four or more measurement light generation units that generate measurement light beams in the area.

Further, when the transmitting unit 1 includes N measurement light generation units (“N” is an integer of 2 or more) that generate measurement light beams in different wavelength ranges, the type identification unit 302 identifies the N measurement light generation units. Among the N measurement light beams generated by the measurement light generation section of The type of the object At can be identified using the reflectance (that is, using the reflectance of the object At at M different wavelengths). By performing identification using at least two reflectances, it is possible to sufficiently ensure the accuracy of identification, and as the number of reflectances used increases, the accuracy of identification further increases. Conversely, as the number of reflectances used decreases, the processing burden associated with identification becomes smaller.

<6-4. Fourth modification>
In the transmitting unit 1 according to the embodiment described above, the light guiding unit 13 can be realized using various configurations that can guide a light beam. For example, the light guiding section 13 may include a MEMS (Micro Electro Mechanical Systems) mirror configured to be rotatable around two orthogonal axes. Further, the light guide section 13 may include various types of spatial phase modulation elements 131 other than the grating light valve 5, and may include, for example, a planar light valve (PLV). Specifically, the planar light valve has, for example, a configuration in which a plurality of lattice elements (for example, circular lattice elements in a plan view) are arranged in a matrix on a substrate, and the plurality of lattice elements 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.

However, when guiding a light beam whose wavelength changes continuously (i.e., a wavelength-swept light beam) using a MEMS mirror, the MEMS mirror continues to move while the wavelength of the light beam is changed. There is a possibility that the waveform of the light beam projected onto the scanning area A may be distorted or the direction (scanning angle) in which the light beam is guided may be shifted. On the other hand, when guiding a light beam whose wavelength changes continuously using a spatial phase modulation element 131 such as a grating light valve 5 or a plane light valve, for example, one period of wavelength sweeping is performed. During this period, the grating element (ribbon 52 in the case of the grating light valve 5) of the spatial phase modulation element 131 is kept stationary so that the scanning angle of the light beam does not change. The displacement mode of the grating element can be changed (that is, the scanning angle can be changed) at the timing when the periodic wavelength sweep is started. Therefore, the above situation is unlikely to occur. In other words, by providing the light guide section 13 with the spatial phase modulation element 131, it is possible to appropriately guide the measurement light beams La, Lb, and Lc whose wavelengths continuously change into the scanning area A. can. Furthermore, in the spatial phase modulation element 131, the grating element can be operated at high speed (for example, in the case of the grating light valve 5, the ribbon 52 can be operated at a high speed of 100 kHz or more). Therefore, it is possible to change the displacement mode of the grating elements instantaneously, thereby reducing the time required to scan the scanning area A while appropriately guiding the measurement light beams La, Lb, and Lc to the scanning area A. It becomes possible to suppress the time to a sufficiently short time. For the above reasons, when a light beam whose wavelength changes continuously is used as the measurement light beams La, Lb, and Lc, it is particularly preferable that the light guide section 13 is configured to include the spatial phase modulation element 131. preferable.

<6-5. Fifth modification>
In the above embodiment, in the reflectance data D, the reflectances Tia, Tib, and Tic of each wavelength λa, λb, and λc are described for each candidate type Ti in a table format. It is not limited to the configuration. For example, assume that a function representing the reflectance characteristics of each candidate type Ti is held as the reflectance data D, and this is used to specify the reflectance Tia, Tib, and Tic of each wavelength λa, λb, and λc. Good too. With such a configuration, no matter what wavelength is adopted as the measurement light beam, it is possible to specify the reflectance of each candidate type Ti at that wavelength.

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

For example, the projection optical system of the transmitter 1 has a function of increasing the reflection angle of the collective light beam L by the spatial phase modulation element 131 to widen the guiding range (scanning angle range) of the collective light beam L. It's okay. This function can be realized, for example, by focusing the collective light beam L at a position in front of the scanning area A as in the above embodiment, or it can also be realized by a combination of a plurality of lenses.

Furthermore, the transmitter 1 may further include a polarizing beam splitter and a quarter wavelength plate. Specifically, for example, the collective light beam L emitted from the lens 103 is bent at right angles by a polarizing beam splitter, passed through a quarter-wave plate, and then made incident on the spatial phase modulation element 131, and further, A configuration may also be adopted in which the collective light beam L reflected by the spatial phase modulation element 131 is made to pass through the quarter-wave plate again and then enter the polarizing beam splitter. In this case, the collective light beam L is rotated by 1/4 wavelength as it passes through the 1/4 wavelength plate the first time, and then enters the spatial phase modulation element 131 and is reflected there. The light is further rotated by a quarter wavelength as it passes through the quarter wavelength plate, and then enters the polarizing beam splitter. Here, the collective light beam L incident on the polarizing beam splitter is rotated by 1/2 wavelength by passing through the 1/4 wavelength plate twice, so it passes through the polarizing beam splitter and heads toward the projection optical system. Become.

Further, each of the photodetectors 22a, 22b, and 22c of the receiving section 2 may include, for example, a two-dimensional photodetector array in which photodetectors 221 are arranged two-dimensionally.

Further, in the receiving section 2, for example, a microlens array in which a plurality of microlenses are arranged one-dimensionally is placed between each filter 23a, 23b, 23c and each photodetector 22a, 22b, 22c. It may also be configured such that each microlens is provided in correspondence with each photodetector 221, and each microlens images each of the measurement light beams La, Lb, and Lc incident thereon on each corresponding photodetector 221.

In the receiving section 2, for example, between each filter 23a, 23b, 23c and each photodetector 22a, 22b, 22c (if a microlens is provided, the microlens and each photodetector 22a, 22b, 22c (between the Reference light beams L0a, L0b, and L0c corresponding to La, Lb, and Lc may be incident. In such a configuration, each measurement light beam La, Lb, Lc and each corresponding reference light beam L0a, L0b, L0c are superimposed by each light combining element and enter each photodetector 221. Therefore, each photodetector 221 of each photodetector 22a, 22b, 22c detects a composite wave of each measurement light beam La, Lb, Lc and the corresponding reference light beam L0a, L0b, L0c.

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

For example, in the above embodiment, the measurement data acquired by the control unit 3 may be one of the distance to the object At and the position of the object At, or various other data (for example, velocity of the target object At) may be acquired as the 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.

As mentioned above, although the detection device 100 and the detection method have been explained in detail, the above explanation is an example in all aspects, and is not limited thereto. 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 embodiment and each modification can be appropriately combined or omitted as long as they do not contradict each other.

100 Detection device 1 Transmission section 11a First measurement light generation section 11b Second measurement light generation section 11c Third measurement light generation section 12 Merging section 13 Light guiding section 131 Spatial phase modulation element 2 Receiving section 21 Branching section 22a First light detection 22b 2nd photodetector 22c 3rd photodetector 23a 1st filter 23b 2nd filter 23c 3rd filter 3 Control section 301a 1st reflectance specifying section 301b 2nd reflectance specifying section 301c 3rd reflectance specifying section 302 Type identification part D Reflectance data La 1st 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 (6)

a transmitter that transmits light to a scanning area;
a receiving unit that receives light reflected by an object in the scanning area;
Equipped with
The transmitter includes:
a first measurement light generation unit that generates a first measurement light whose wavelength changes continuously from the first wavelength;
a second measurement light generation unit that generates a 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;
A detection device comprising: The detection device according to claim 1,
The transmitter includes:
a merging section that merges the first measurement light and the second measurement light to form a collective light, and causes the collective light to enter the light guiding section;
Equipped with
The receiving section,
a branching part that branches the collective light reflected by the target object;
A frequency band that is disposed on the optical path of one of the plurality of branched collective lights, attenuates frequency bands other than the frequency band corresponding to the first measurement light, and also attenuates frequency bands corresponding to the first measurement light. a first filter that passes through the
Disposed on the optical path of another one of the plurality of branched collective lights, attenuating frequency bands other than the frequency band corresponding to the second measurement light, and corresponding to the second measurement light. a second filter that passes the frequency band;
a first photodetector that detects the light that has passed through the first filter;
a second photodetector that detects the light that has passed through the second filter;
A detection device comprising: The detection device according to claim 2,
a first reflectance identifying unit that identifies a first reflectance that is a reflectance of the object at the first wavelength based on a detection result by the first photodetector;
a second reflectance identifying unit that identifies a second reflectance that 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 the 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,
a storage unit that stores reflectance data describing, for each of the 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;
Equipped with
The type identification section,
comparing the reflectance of the object and 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. The detection device according to any one of claims 1 to 4,
The light guide section is
a spatial phase modulation element that has a plurality of grating elements and modulates the phase of incident light by displacing each of the plurality of grating elements to guide the light;
A detection device comprising: a transmitting step of transmitting light to the scanning area;
a receiving step of receiving light reflected by an object in the scanning area;
Equipped with
The sending step includes:
A measurement light generation step of generating first measurement light whose wavelength changes continuously from a first wavelength, and generating second measurement light whose wavelength changes continuously from a second wavelength different from the first wavelength. and,
a merging step of merging the first measurement light and the second measurement light into collective light;
a light guiding step of guiding the collective light to scan the scanning area;
Equipped with
The receiving step includes:
a branching step of branching the collective light reflected by the target object;
One of the plurality of branched aggregated lights is detected after attenuating frequency bands other than the frequency band corresponding to the first measurement light, and another of the plurality of branched aggregated lights is detected. a light detection step of detecting one collective light after attenuating frequency bands other than the frequency band corresponding to the second measurement light;
A detection method comprising:

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