JP2024002549A - Detection device and detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique that can extend measuring distance when detection and distance measurement using light are performed.

SOLUTION: A detection device 100 includes a transmitting section that transmits light to a scanning area A, and a receiving section that receives light reflected by a target object in the scanning area A. The transmitting section includes a light source 11 that emits light, a light guide section 12 that modulates the phase of the light to guide the light in a first direction Ax, and has the scanning area A scanned, and a molding section 13 that shapes light so that the light projected onto the scanning area A becomes a modified line beam Ld in which a plurality of collimated beams C are arranged with gaps provided along a second direction Ay that intersects the first direction Ax.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2024,JPO&INPIT

Description

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

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, the light reflected by the object is detected, and the distance to the object is determined based on the time it takes for the light to bounce back. Calculate etc.

JP 2021-184067 Publication

In LiDAR technology, the higher the power (output) of the light source used, the higher the intensity of the light irradiated onto the object, and the higher the intensity of the reflected light that is reflected back. ) becomes longer. However, in LiDAR devices installed in automobiles, it is necessary to ensure eye safety, so the power of the light source cannot be increased indefinitely. For this reason, it is required to extend the distance measurement as much as possible while the power of the light source is limited.

Here, as shown in FIG. 16, LiDAR devices have various methods of irradiating light to the surrounding area, and even if the power of the light source is the same, distance measurement depends on the method of irradiating light. Distances are different.

For example, in the method (2D flash method) P1, which emits light that spreads two-dimensionally and irradiates the two-dimensionally spread area all at once, the light emitted from the light source spreads two-dimensionally and irradiates the area. Therefore, the intensity (power density) of light irradiated per unit area becomes low. Therefore, only a relatively short measuring distance can be achieved. On the other hand, the 2D flash method P1 can instantaneously irradiate the entire two-dimensional area with light, and thus achieves a high frame rate.

On the other hand, method P2 (2D raster scan method) in which a collimated beam is emitted and moved in two directions to scan a two-dimensionally spread area to irradiate the area with light (2D raster scan method) Since the light is irradiated without being spread out, the intensity of the light irradiated per unit area is relatively high. Therefore, a relatively long measuring distance is achieved. On the other hand, the 2D raster scan method P2 requires a certain amount of time to irradiate the entire two-dimensional area with light, making it difficult to increase the frame rate.

As described above, since the measured distance is in a trade-off relationship with the frame rate, an attempt to increase the measured distance inevitably causes a decrease in the frame rate. In this process, by emitting light (line beam) Ln that spreads one-dimensionally, and moving the line beam Ln in a direction that intersects (for example, perpendicularly) with the extending direction of the line beam Ln to scan an area that spreads two-dimensionally. The method (1D line scan method) P3 of irradiating light onto the area is a well-balanced method that can achieve both a relatively long measuring distance and a relatively high frame rate.

In this 1D line scan method P3, it is required to further extend the distance measurement while maintaining the frame rate superiority over the 2D raster scan method P2 (that is, without sacrificing the frame rate).

The present disclosure aims to provide a technology that can extend the measured distance when performing detection and distance measurement 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 light source that emits light; a light guide unit that modulates the phase of the light to guide the light in a first direction to scan the scanning area; and a shaping section that shapes the light so that it becomes a modified line beam in which a plurality of collimated beams are arranged with gaps provided along a second direction that intersects with the second direction.

A second aspect is the detection device according to the first aspect, wherein the receiving section includes a photodetecting section in which a plurality of photodetectors are arranged along the second direction, and the gap between the collimated beams is , configured to correspond to the gap between the photodetectors.

A third aspect is the detection device according to the second aspect, wherein each of the adjacent collimated beams in the deformed line beam is configured to be incident on each of the adjacent photodetectors in the light detection section. .

A fourth aspect is the detection device according to any one of the first to third aspects, wherein the molding section includes a diffractive optical element in which a diffraction grating pattern is formed by a concavo-convex structure, and the diffraction grating pattern Shapes the light by diffracting it.

A fifth aspect is the detection device according to any one of the first to third aspects, wherein the molding section has a plurality of lattice elements arranged two-dimensionally, and each of the plurality of lattice elements The device includes a two-dimensional spatial phase modulation element that forms a diffraction grating pattern by driving, and shapes the light by diffracting the light with the diffraction grating pattern.

A sixth aspect is the detection device according to the fifth aspect, wherein the two-dimensional spatial phase modulation element is shared between the light guiding section and the shaping section, and the two-dimensional spatial phase modulation element is shared between the light guide section and the shaping section. A modulation element directs and shapes the light.

A seventh aspect is the detection device according to the fifth or sixth aspect, wherein in the two-dimensional spatial phase modulation element, a pattern changing unit that changes a diffraction grating pattern formed by the plurality of grating elements; Equipped with

An eighth aspect is the detection device according to the seventh aspect, in which the pattern changing unit includes one collimated beam at an end in the second direction in the deformed line beam projected onto the scanning area. The diffraction grating pattern is changed so that the diffraction grating pattern disappears.

A ninth aspect is the detection device according to the seventh or eighth aspect, in which the pattern changing section detects the plurality of deformed line beams projected onto the scanning area through a lens included in the transmitting section. The diffraction grating pattern is corrected in consideration of the aberration of the lens so that the collimated beams are arranged at equal intervals.

A tenth 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, wherein the transmitting step includes: an emitting step of emitting light, a light guiding step of guiding the light in a first direction to scan the scanning area by modulating the phase of the light, and before the light guiding step and after the light guiding step. Alternatively, in parallel with the light guiding step, the light projected onto the scanning area is a modified line beam in which a plurality of collimated beams are arranged with gaps provided along a second direction intersecting the first direction. and a molding step of molding the light so that it becomes .

According to the first to tenth aspects, the deformed line beam in which the plurality of collimated beams are arranged with gaps provided along the second direction intersecting the first direction is guided in the first direction to scan the scanning area. By doing so, light is irradiated onto a scanning area that spreads two-dimensionally. The modified line beam irradiates light onto a region consisting of a collection of discontinuous parts (for example, line segments) arranged linearly along the second direction. Compared to a normal line beam that irradiates light onto a linear area that extends across the area, the intensity (power density) of the light is higher in the area where the light is irradiated. Therefore, by scanning the scanning area with the modified line beam, the distance to be measured can be extended compared to the case where the scanning area is scanned with the normal line beam.

According to the second aspect, the light that was incident on the gap of the photodetector in a normal line beam (that is, the light that was lost without being detected, in other words, the light that was a fill factor loss of the photodetector) ), the intensity of the light irradiated to the scanning area is increased and the distance measurement is extended. Therefore, it is possible to extend the measured distance while suppressing a decrease in resolution.

According to the third aspect, the gaps between the plurality of collimated beams in the deformed line beam do not straddle the photodetector, so that deterioration in resolution is sufficiently suppressed. On the other hand, for all the gaps that exist between the multiple photodetectors that the modified line beam is incident on, at least a portion of the light that was incident on each gap will be thinned out, so the distance measurement can be made sufficiently It can be extended. In other words, it is possible to sufficiently extend the measured distance while sufficiently suppressing a decrease in resolution.

According to the fourth and fifth aspects, light can be easily shaped using the light diffraction phenomenon.

According to the sixth aspect, the number of parts can be reduced and the device configuration can be simplified.

According to the seventh aspect, by changing the diffraction grating pattern, the arrangement pattern of the collimated beams in the modified line beam projected onto the scanning area can be changed.

According to the eighth aspect, in the deformed line beam, one or more collimated beams at the end in the second direction are eliminated, so that the total number of collimated beams included in the deformed line beam is reduced, and the remaining collimated beams are Strength can be increased. This makes it possible to further extend the measured distance.

According to the ninth aspect, the diffraction grating pattern is corrected by taking into account the aberration of the lens included in the transmitting section, so that a plurality of collimated beams are generated in the deformed line beam projected onto the scanning area due to the aberration of the lens. This prevents the occurrence of a situation in which the distance between the collimated beams widens (or narrows) as it approaches the end in the arrangement direction of the collimated beams.

FIG. 1 is a block diagram showing a schematic configuration of a detection device according to a first embodiment. FIG. 2 is a schematic diagram for explaining a detection device. 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 is a diagram schematically showing the optical system of the detection device as seen along the direction in which the light beam is guided by the light guiding section. FIG. 3 is a diagram schematically showing the optical system of the detection device as seen along the arrangement direction of a plurality of collimated beams in a deformed line beam. FIG. 3 is a diagram showing the flow of operations performed by the detection device. FIG. 7 is a schematic diagram for explaining a detection device according to a first modification. FIG. 2 is a plan view schematically showing a part of the planar light valve. FIG. 7 is a schematic diagram for explaining a detection device according to a second modification. FIG. 7 is a schematic diagram for explaining an example of the operation of a detection device according to a third modification. FIG. 7 is a schematic diagram for explaining an example of the operation of a detection device according to a third modification. FIG. 7 is a schematic diagram for explaining another example of an arrangement pattern of collimated beams in a modified line beam. FIG. 3 is a schematic diagram for explaining a method of irradiating light to a surrounding area.

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 FIGS. 1 and 2. FIG. 1 is a block diagram showing a schematic configuration of a detection device 100. FIG. 2 is a schematic diagram for explaining the detection device 100. In the figures referred to below (in particular, FIG. 2 and FIGS. 10, 12, 13, and 14 referred to below), elements that appear in the figures are simplified and exaggerated for illustrative purposes. , their arrangement and shape are also schematic. Further, illustration of some elements is omitted.

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

(Transmitter 1)
The transmitting section 1 includes a light source 11, a light guiding section 12, and a shaping section 13.

The light source 11 emits a light beam L. Specifically, for example, the light source 11 is configured to include a semiconductor laser. Further, the light beam L emitted from the light source 11 is specifically, for example, a short pulse laser beam (for example, a short pulse of about 1 to 2 nsec). The wavelength of the light beam L is, for example, a wavelength suitable for use in a LiDAR device (i.e., it satisfies the requirements such as easily passing through water, being less affected by sunlight, ensuring safety for human eyes, etc.) It is preferable that the wavelength is Specifically, for example, the wavelength of the light beam L is preferably 850 nm or more and 1550 nm or less, and particularly preferably has a center wavelength of 850 nm, 905 nm, 1064 nm, or 1550 nm.

The light guide unit 12 guides the light beam L incident thereon in a predetermined direction (hereinafter also referred to as "first direction") Ax to scan the scanning area A. Specifically, the light guide section 12 is configured to include, for example, a spatial phase modulation element 121 which is a type of phase modulation spatial light modulator. The spatial phase modulation element 121 has a plurality of grating elements, modulates the phase of the incident light beam L by driving (specifically, displacing) each of the plurality of grating elements, and modulates the phase of the incident light beam L. Guide beam L. In this embodiment, the spatial phase modulation element 121 is realized using a grating light valve 5, which is a type of optical phased array.

The shaping unit 13 shapes the light beam L so that the light projected onto the scanning area A becomes a modified line beam Ld. Here, the "deformed line beam Ld" is a direction in which a plurality of collimated beams C intersect with a predetermined direction (the first direction Ax, which is the direction in which the light beam L is guided by the light guiding unit 12) while providing a gap. , hereinafter also referred to as the "second direction"). When the scanning area A is irradiated with such a modified line beam Ld, the light is irradiated onto an area consisting of a collection of discontinuous portions (for example, line segments) arranged linearly along the second direction Ay. It turns out. By shaping the light beam L into such a modified line beam Ld and irradiating it onto the scanning area A, the same light beam L can be transformed into a normal line beam Ln (that is, a linear beam extending continuously along a predetermined direction). It is possible to increase the intensity (power density) of the light in the area where the light is irradiated, compared to the case where the light is formed into a normal line beam Ln) (FIG. 16) that irradiates the area.

The shaping section 13 may shape the light beam L in any manner. In this embodiment, the molding section 13 includes a diffractive optical element (DOE) 4 . The diffractive optical element 4 is an optical element that shapes light using the diffraction phenomenon of light. For example, a diffraction grating pattern is formed by a fine uneven structure carved on the main surface of a plate-shaped base material. It is something that The light beam L incident on the diffraction optical element 4 is diffracted according to the diffraction grating pattern formed by the uneven structure (it is given a phase distribution according to the diffraction grating pattern). molded into the desired shape (molding pattern). That is, by using the diffractive optical element 4 provided with a diffraction grating pattern designed according to a desired shaping pattern, the light beam L can be shaped into the desired shaping pattern.

The diffractive optical element 4 that shapes the light beam L so that the light projected onto the scanning area A becomes the modified line beam Ld can be obtained, for example, as follows. First, the modified line beam Ld to be projected onto the scanning area A is determined. That is, the arrangement pattern of the collimated beams C in the modified line beam Ld (specifically, for example, the number of collimated beams C, the interval (pitch), the beam diameter, the profile, etc.) is determined. Then, a diffraction grating pattern is designed based on the determined modified line beam Ld. That is, a diffraction grating pattern that can shape the light beam L so that the light projected onto the scanning area A becomes the determined modified line beam Ld is designed, for example, by simulation. The diffractive optical element 4 is obtained by carving the thus designed diffraction grating pattern on a base material. By using the diffractive optical element 4 thus obtained, the light beam L can be shaped so that the light projected onto the scanning area A becomes the desired deformed line beam Ld. In other words, it is possible to impart a phase distribution to the light beam L such that the light projected onto the scanning area A becomes the desired modified line beam Ld.

(Receiving section 2)
The receiver 2 includes a photodetector 21 .

The light detection unit 21 receives the deformed line beam Ld that is irradiated onto the scanning area A and is reflected by the object At located there through the lens 201 or the like, and detects the received deformed line beam Ld. Specifically, the photodetector 21 includes, for example, a so-called one-dimensional photodetector array in which a plurality of photodetectors (light receiving elements) 211 are arranged in one dimension (one row). As an example, the photodetector 21 can be configured to include a so-called one-dimensional array SPAD in which SPADs (Single Photon Avalanche Diodes) serving as the photodetector 211 are arranged in a row.

The photodetector 21 is arranged such that the arrangement direction of the photodetectors 211 is along the arrangement direction (second direction) Ay of the plurality of collimated beams C in the modified line beam Ld. Here, the arrangement pattern of the collimated beams C is defined such that the gap between the collimated beams C in the modified line beam Ld corresponds to the gap between the photodetectors 211 in the photodetector 21. Specifically, the diffraction grating pattern provided in the diffractive optical element 4 is designed so that the modified line beam Ld in which the collimated beams C are arranged in such an arrangement pattern is obtained. Here, "the gap between the collimated beams C corresponds to the gap between the photodetectors 211" means that when the deformed line beam Ld is incident on the photodetector 21, at least a part of the gap between the collimated beams C corresponds to the gaps between the photodetectors 211 means that it coincides with at least part of the gap between In other words, in this modified line beam Ld, the light that was incident on the gap between the photodetectors 211 in the normal line beam Ln (that is, the light that was lost without being detected, in other words, the fill factor loss of the photodetector 21 At least a portion of the light (which had previously become

In particular, as shown in FIG. 2, the arrangement pattern of the collimated beams C is defined such that each of the adjacent collimated beams C in the deformed line beam Ld is incident on each of the adjacent photodetectors 211 in the photodetector 21. It is preferable that Specifically, for example, the arrangement pitch of the collimated beams C in the deformed line beam Ld when incident on the photodetector 21 (the distance between the center lines of adjacent collimated beams C) is the arrangement pitch of the photodetectors 211 (the distance between the adjacent photodetectors 211 It is preferable that the arrangement pattern of the collimated beams C is defined so as to substantially match the distance between the center lines of the collimated beams C. Further, the number of collimated beams C included in the deformed line beam Ld is set to be the same as the number of photodetectors 211 included in the photodetector 21 (that is, the collimated beams are applied to all of the plurality of photodetectors 211 included in the photodetector 21). It is also preferable that the arrangement pattern of the collimated beam C is defined such that the collimated beam C is incident. Furthermore, the arrangement pattern of the collimated beams C is defined so that the beam diameter of each collimated beam C in the modified line beam Ld when incident on the photodetector 21 substantially matches the diameter of the light receiving surface of each photodetector 211. It is also preferable that

(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. Can be done. 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, an example of the configuration of the grating light valve 5, which is the spatial phase modulation element 121 included in the light guide section 12, will be explained first, and then an example of the overall configuration of the detection device 100 including the spatial phase modulation element 121 will be explained. .

<2-1. Grating light valve＞
The grating light valve 5 will be explained with reference to FIGS. 4 to 6. FIG. 4 is a plan view schematically showing a part of the grating light valve 5. As shown in FIG. FIG. 5 is a side view schematically showing the grating light valve 5. As shown in FIG. FIG. 6 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. 4 to 6, 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. Each ribbon 52 also includes a reflective surface 521 provided on its upper surface (a surface opposite to the surface facing the substrate 511) that specularly reflects the light beam L. 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. 5). state). Furthermore, 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. 5). 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 beam L 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 L incident thereon and reflects the light beam L 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), the angle at which the light beam L is reflected from the grating light valve 5 can be successively changed. becomes possible. In this way, by successively changing the direction in which the light beam L is emitted, the light beam L 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. 7 and 8. FIG. 7 is a diagram schematically showing the optical system of the detection device 100 as seen along the first direction Ax (that is, the direction in which the light beam L is guided by the light guide section 12), and FIG. It is a figure which shows typically the optical system of the detection apparatus 100 seen along Ay (namely, the arrangement direction of the several collimated beam C in the deformed line beam Ld).

When viewed along the first direction Ax (FIG. 7), the light beam (measurement light beam) L emitted from the light source 11 is collimated in the second direction Ay by the cylindrical lens 101. As described above, the light beam L emitted from the light source 11 is, for example, a short-pulse laser beam.

Subsequently, the light beam L enters the lens 102, and is focused by the lens 102 onto the center of the spatial phase modulation element 121 in the second direction Ay. As described above, the spatial phase modulation element 121 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 light beam L is focused by the lens 102 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 light beam L is incident on the central region, the spatial phase It becomes possible to control the angle (scanning angle) of the light beam L reflected from the modulation element 121 with sufficiently high precision.

The light beam L reflected by the spatial phase modulation element 121 enters the lens 103, is collimated by the lens 103 in the second direction Ay, and then enters the diffractive optical element 4. The diffractive optical element 4 plays a role as the molding section 13 and is arranged, for example, on the Fourier plane in front of the lens 104. As described above, the diffractive optical element 4 has a diffraction grating pattern designed in advance (that is, the light beam L can be shaped so that the light projected onto the scanning area A becomes the desired deformed line beam Ld). A diffraction grating pattern) is provided, and the light beam L incident on the diffraction optical element 4 is diffracted according to the diffraction grating pattern, so that the light projected onto the scanning area A forms the desired deformation line. It is shaped into a beam Ld. In other words, the light beam L is given a phase distribution such that the light projected onto the scanning area A becomes the desired modified line beam Ld.

The light beam L shaped by the diffractive optical element 4 enters the lens 104, and is imaged by the lens 104 in the second direction Ay. An imaging point on which the light beam L is imaged by the lens 104 is defined between the lens 104 and the scanning area A. Therefore, the light beam L enters the scanning area A while expanding in the second direction Ay. That is, the projection optical system including a group of lenses 103 and 104 shapes the light beam L so as to spread it in the second direction Ay, and irradiates the scanning area A with the light beam L. As mentioned above, since the light beam L is shaped by the diffractive optical element 4, the light projected onto the scanning area A through the lens 105 is divided into a plurality of collimated beams C along the second direction Ay. This results in a modified line beam Ld arranged while providing the following.

On the other hand, when viewed along the second direction Ay (FIG. 8), although the light beam L emitted from the light source 11 is incident on the cylindrical lens 101, the cylindrical lens 101 has no power in the first direction Ax. do not have. Therefore, the light beam L emitted from the light source 11 travels without being refracted by the cylindrical lens 101 in the first direction Ax.

Subsequently, the light beam L enters the lens 102, is collimated by the lens 102 in the first direction Ax, and then enters the spatial phase modulation element 121. That is, the light beam L is incident on a strip-shaped region that extends long and narrow along the arrangement direction Gx of each ribbon 52 of the grating light valve 5 that realizes the spatial phase modulation element 121. As described above, in the grating light valve 5, phase modulation is performed on the light beam L by controlling the displacement amount ΔG of each of the plurality of ribbons 52 using a signal from the control unit 3, and the light beam L is , is reflected at an angle (scanning angle) according to the displacement mode (mode) of the plurality of ribbons 52. Then, by successively changing the angle at which the light beam L is reflected, the light beam L is guided in the first direction Ax. In FIG. 8, light beams L reflected at two different angles are also shown.

The light beam L reflected by the spatial phase modulation element 121 enters the lens 103, is imaged by the lens 103 in the first direction Ax, and is then collimated by the lens 104 in the first direction Ax. In other words, the projection optical system including a group of lenses 103 and 104 shapes the light beam L emitted from the spatial phase modulation element 121 so as to narrow it in the first direction Ax, and irradiates it onto the scanning area A. do.

As described above, in the transmitting unit 1, the spatial phase modulation element 121 (specifically, the grating light valve 5) of the light guide unit 12 successively changes the angle at which the light beam L incident thereon is reflected. , the light beam L is guided in the first direction Ax, while the shaping unit 13 (specifically, the diffractive optical element 4) guides the light beam L to be projected onto the scanning area A along the second direction Ay. The light beam L is shaped so that it becomes a modified line beam Ld in which a plurality of collimated beams C are arranged. Therefore, the deformed line beam Ld, in which a plurality of collimated beams C are arranged along the second direction Ay, is guided in the first direction Ax and scans the scanning area A. Light is irradiated onto a scanning area A that extends two-dimensionally and is defined from two directions Ay. The size of the scanning area A, that is, the field of view (FOV) of the detection device 100 is determined by the entire length of the deformed line beam Ld in the second direction Ay and the guiding range of the light beam L by the light guiding section 12 (the scanning angle). range).

As described above, the modified line beam Ld has a higher light intensity in the irradiated portion than the normal line beam Ln (FIG. 16). Therefore, by scanning the scanning area A with the modified line beam Ld, the distance measurement can be extended compared to when scanning the scanning area A with the normal line beam Ln. On the other hand, when scanning the scanning area A with the modified line beam Ld and scanning the scanning area A with the normal line beam Ln, if the speed at which the light is guided is the same, the frame rate will be the same. It is. Further, if the overall lengths of both line beams Ln and Ld in the second direction Ay are the same, the size of the scanning area A is also the same. That is, by scanning the scanning area A with the modified line beam Ld, it is possible to extend the distance measurement while maintaining the frame rate and field of view (FOV).

Continuing, when viewed along the second direction Ay (FIG. 8), the deformed line beam Ld irradiated onto the scanning area A and reflected by the object At present there passes through a lens (for example, a camera lens) 201, etc. The light is received, enters the photodetector 21, and is detected there.

On the other hand, when viewed along the first direction Ax (FIG. 7), as described above, the photodetector 21 includes a plurality of photodetectors 211, and the arrangement direction of the plurality of photodetectors 211 is arranged along the second direction Ay. will be placed in For example, if the arrangement pattern of the collimated beams C is defined such that each of the adjacent collimated beams C in the deformed line beam Ld is incident on each of the adjacent photodetectors 211 in the photodetector 21, the scanning area A Each of the adjacent collimated beams C in the modified line beam Ld that has been irradiated and returned after being reflected by the object At here is incident on each of the adjacent photodetectors 211, and each photodetector 211 adjusts the intensity of each collimated beam C. will be detected.

The detection result by the photodetector 21 is transmitted to the control section 3, and the control section 3 performs various calculation processes using the detection result. For example, the control unit 3 generates various measurement data regarding the object At in the scanning area A (for example, the distance to the object At, the position of the object At, etc.) based on the detection result by the photodetector 21. Calculate. Specifically, for example, the control unit 3 calculates the measurement data using ToF (Time of Flight) distance measurement technology. In this case, the control unit 3 calculates the distance to the object At from the time (flight time) from when the short pulse laser beam is emitted from the light source 11 until the reflected light is detected by the light detection unit 21. calculate. Further, for example, the control unit 3 controls the first The position of the object At in the direction Ax is specified. 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 211 that has detected the deformed line beam Ld reflected by the object At.

<3. Effect>
The detection device 100 according to the above embodiment includes a transmitter 1 that transmits light (light beam) L to a scanning area A, and a receiver 2 that receives the light beam L reflected by an object At in the scan area A. and. The transmitting unit 1 includes a light source 11 that emits a light beam L, and a light guide unit 12 that modulates the phase of the light beam L to guide the light beam L in the first direction Ax to scan the scanning area A. Then, the light beam is adjusted such that the light projected onto the scanning area A becomes a modified line beam Ld in which a plurality of collimated beams C are arranged with gaps provided along the second direction Ay intersecting the first direction Ax. A molding section 13 that performs molding on L is provided.

According to this configuration, a plurality of collimated beams C are arranged with gaps provided along the second direction Ay that intersects with the first direction Ax (in other words, they are branched into a plurality of collimated beams C). The line beam Ld is guided in the first direction Ax to scan the scanning area A, so that the scanning area A that spreads two-dimensionally is irradiated with light. The modified line beam Ld irradiates light onto a region consisting of a collection of discontinuous portions (for example, line segments) linearly arranged along the second direction Ay. Compared to a normal line beam Ln (Figure 16), which irradiates light onto a linear area that extends continuously along the line, the intensity (power density) of the light is higher in the area where the light is irradiated (another way of saying it is (The transmission efficiency of the light beam L is high). Furthermore, the intensity of the light detected by the photodetector 21 (the intensity of the detection signal) is also high. Therefore, by scanning the scanning area A with the modified line beam Ld, the distance measurement can be extended compared to when scanning the scanning area A with the normal line beam Ln.

In the modified line beam Ld, as the ratio of the gap to the collimated beam C increases, the intensity of the light irradiated onto the scanning area A increases, and the distance measurement becomes longer. On the other hand, as this ratio increases, the possibility that the resolution will decrease in the second direction Ay increases. For example, in a LiDAR device installed in a car, most of the objects that appear in the driving field of view move horizontally, and there are almost no objects that move vertically, so the resolution in the vertical direction is not very high. Not asked for. In other words, a decrease in resolution is allowed in the vertical direction. Therefore, if the detection device 100 is installed so that the second direction Ay corresponds to the vertical direction in which a decrease in resolution is allowed, the decrease in resolution in the second direction Ay may not become a substantial problem. many.

Furthermore, in the detection device 100 according to the embodiment described above, the receiving section 2 includes the photodetecting section 21 in which a plurality of photodetectors 211 are arranged along the second direction Ay. The gap between the collimated beams C is configured to correspond to the gap between the photodetectors 211. According to this configuration, the light that was incident on the gap between the photodetectors 211 in the normal line beam Ln (that is, the light that was lost without being detected, in other words, the fill factor loss of the photodetector 21 By thinning out at least a part of the light), the intensity of the light irradiated onto the scanning area A is increased, and the distance measurement distance is extended. Therefore, it is possible to extend the measured distance while suppressing a decrease in resolution.

In particular, if the configuration is such that each of the adjacent collimated beams C in the deformed line beam Ld is incident on each of the adjacent photodetectors 211 in the photodetector 21, the gaps between the plurality of collimated beams C in the deformed line beam Ld are Since it does not straddle the photodetector 211, deterioration in resolution is sufficiently suppressed. On the other hand, with this configuration, for all of the gaps that exist between the plurality of photodetectors 211 into which the modified line beam Ld is incident, at least a part of the light that was incident on each gap is thinned out. Therefore, the measuring distance can be extended sufficiently. In other words, by configuring each of the adjacent collimated beams C to be incident on each of the adjacent photodetectors 211, it is possible to sufficiently extend the distance measurement while sufficiently suppressing a decrease in resolution.

Further, in the detection device 100 according to the above embodiment, the molding unit 13 includes the diffraction optical element 4 in which a diffraction grating pattern is formed by a concavo-convex structure, and the light beam L is diffracted by the diffraction grating pattern. Shape L. According to this configuration, the light beam L can be easily shaped using the light diffraction phenomenon.

Further, the detection method performed in the detection device 100 according to the above embodiment includes a transmission step S1 (operation step in the transmitter 1) of transmitting light (light beam) L to the scanning area A, as shown in FIG. ), a reception process S2 (operation process in the reception unit 2) that receives the light beam L reflected by the target object At in the scanning area A, and arithmetic processing based on the detection results obtained in the reception process S2. The calculation step S3 (operation step in the control unit 3) is included. Then, the transmitting step S1 includes an emitting step S11 of emitting the light beam L from the light source 11, and modulating the phase of the light beam L emitted from the light source 11 to guide the light beam L in the first direction Ax. A light guiding step S12 (operating step in the light guiding section 12) for scanning the scanning area A, and a plurality of collimated beams in which the light projected onto the scanning area A is aligned in the second direction Ay intersecting the first direction Ax. A shaping step S13 (operation step in the shaping section 13) is provided in which the light beam L is shaped so that the light beams C become a modified line beam Ld arranged with gaps. Further, the reception step S2 includes a photodetection step S21 (operation step in the photodetection section 21) of receiving and detecting the modified line beam Ld reflected by the object At in the scanning area A. Further, a calculation step S3 includes a measurement data calculation step S31 (an operation step in the control unit 3) in which various measurement data regarding the object At in the scanning area A is calculated based on the detection results obtained in the light detection step S21. ).

According to this detection method, by scanning the scanning area A with the modified line beam Ld, the distance to be measured can be extended compared to when scanning the scanning area A with the normal line beam Ln (FIG. 16). In the above embodiment, the molding section 13 (specifically, the diffractive optical element 4) is arranged after the spatial phase modulation element 121 (specifically, the grating light valve 5) of the light guiding section 12. (FIG. 7, FIG. 8), and the molding step S13 was performed after the light guiding step S12, but as in a modification described later, the molding step S13 was performed in parallel with the light guiding step S12. Alternatively, the molding step S13 may be performed before the light guiding step S12.

<4. Modified example>
<4-1. First modification>
Although the molding section 13 of the detection device 100 according to the embodiment described above is configured to include the diffractive optical element 4, the configuration of the molding section 13 is not limited to this. For example, the molded part 13a may be configured to include a planar light valve (PLV) 6, as in a detection device 100a shown in FIG. Specifically, for example, in the optical system (FIGS. 7 and 8) of the detection device 100 according to the above embodiment, a flat light valve is installed in place of the diffractive optical element 4 at the position where the diffractive optical element 4 was disposed. 6 may be placed.

Like the grating light valve 5, the planar light valve 6 is a type of spatial phase modulation element. That is, the planar light valve 6 has a plurality of grating elements, and modulates the phase of the incident light beam L by driving (specifically, displacing) each of the plurality of grating elements. However, while the grating light valve 5 is a one-dimensional spatial phase modulation element in which ribbons 52, which are grating elements, are arranged one-dimensionally, the planar light valve 6 is a reflective element 62, which is a grating element (described later). ) are two-dimensional spatial phase modulation elements arranged in two dimensions.

The planar light valve 6 will be specifically explained with reference to FIG. 11. FIG. 11 is a plan view schematically showing a part of the flat light valve 6. As shown in FIG.

The planar light valve 6 includes a base portion 61 and a plurality of reflective elements 62.

The base portion 61 includes a substrate 611 and an electrode (base electrode) (not shown). The substrate 611 is a plate-shaped base material, and is configured using, for example, a silicon substrate. On the other hand, the base electrode is an electrode provided on the substrate 611, and is realized, for example, by a metal film formed on the upper surface of the substrate 611 (the main surface on the side where the reflective element 62 is provided).

Each of the plurality of reflective elements 62 plays a role as a grating element in the planar light valve 6. The plurality of reflective elements 62 are arranged in a matrix on one main surface of the substrate 611.

The reflective element 62 is a rectangular flat member in plan view, and is supported on the substrate 611 with a gap having a substantially uniform thickness provided between its lower surface and the substrate 611. A reflective surface that specularly reflects the light beam L is provided on the upper surface of the reflective element 62. The reflective surface is realized, for example, by a thin film of metal (for example, aluminum) formed on the upper surface of the reflective element 62. Each reflective element 62 is supported above the substrate 611 by a flexible support 621 while providing a gap with the substrate 611. Specifically, the support body 621 is, for example, a cross-shaped structure in plan view, and the central portion in plan view is connected or integrated with the lower surface of the reflective element 62 (the surface facing the substrate 611). be done. Further, the support body 621 is provided so that a portion from the center portion to each end portion in a plan view spans between the reflective element 62 and the substrate 611. Further, the support body 621 is coated with, for example, a thin film of metal (eg, aluminum), and this thin film constitutes an electrode (reflective element electrode) provided on the reflective element 62.

As described above, the support body 621 that supports the reflective element 62 has flexibility. Therefore, when a potential difference is applied between the base electrode and the reflective element electrode, the support body 6221 is bent toward the substrate 611 due to electrostatic force, and the reflective element 62 is displaced in the normal direction of the substrate 611. Further, when the potential difference between the two electrodes disappears, the electrostatic force disappears, the support body 621 elastically returns to its undeflected state, and the reflective element 62 also returns to its original position. A potential difference according to a signal from the control unit 3 is applied between both electrodes, and each reflective element 62 is displaced with respect to the substrate 611 by an amount corresponding to the applied potential difference. That is, the amount of displacement of the reflective element 62 with respect to the substrate 611 is controlled by a signal from the control section 3.

In the planar light valve 6, by driving the plurality of reflective elements 62 (specifically, by controlling the amount of displacement of each reflective element 62 with a signal from the control unit 3), the plurality of reflective elements 62 can form various modes (patterns). That is, in the planar light valve 6, by controlling the amount of displacement of each reflective element 62 using a signal from the control unit 3, for example, the diffraction grating pattern formed in the diffractive optical element 4 according to the above embodiment (i.e. A diffraction grating pattern similar to the diffraction grating pattern (formed by a fine uneven structure carved on the main surface of the base material) can be formed by the plurality of reflective elements 62.

The light beam L incident on the plane light valve 6 is diffracted according to the diffraction grating pattern formed by the plurality of reflection elements 62 (it is given a phase distribution according to the diffraction grating pattern). It is molded into a shape (molding pattern) according to the grid pattern. That is, each reflective element 62 is displaced so that a diffraction grating pattern designed according to a desired molding pattern is formed by a plurality of reflective elements 62 (specifically, a control signal given to each reflective element 62 is (prescribed), the light beam L can be shaped into the desired shaping pattern.

A control signal capable of shaping the light beam L so that the light projected onto the scanning area A becomes the modified line beam Ld can be obtained, for example, as follows. First, the modified line beam Ld to be projected onto the scanning area A is determined. Then, a diffraction grating pattern is designed based on the determined modified line beam Ld. That is, a diffraction grating pattern that can shape the light beam L so that the light projected onto the scanning area A becomes the determined modified line beam Ld is designed, for example, by simulation. Then, a control signal to be given to each reflective element 62 in order to form the diffraction grating pattern designed in this way is calculated. By displacing each reflective element 62 using the calculated control signal, the light beam L can be shaped so that the light projected onto the scanning area A becomes the desired modified line beam Ld. In other words, it is possible to impart a phase distribution to the light beam L such that the light projected onto the scanning area A becomes the desired modified line beam Ld.

In this way, in the detection device 100a according to the first modification, the molding section 13a includes the planar light valve 6, which is a two-dimensional spatial phase modulation element. The planar light valve 6 has a plurality of reflective elements 62 that are two-dimensionally arranged grating elements, and each of the plurality of reflective elements 62 is driven (specifically, by a signal from the control unit 3). A diffraction grating pattern is formed by the diffraction grating pattern, and the light is shaped by being diffracted by the diffraction grating pattern. According to this configuration, light can be easily shaped using the light diffraction phenomenon.

<4-2. Second modification>
Further, for example, as in the detection device 100b shown in FIG. 12, the flat light valve 6 may be shared between the light guiding section 12b and the molding section 13b. Specifically, for example, in the optical system (FIGS. 7 and 8) of the detection device 100 according to the above-described embodiment, a planar light valve 6 is installed in place of the grating light valve 5 at the location where the grating light valve 5 was disposed. may be arranged, and the diffractive optical element 4 may be omitted.

As described above, in the planar light valve 6, it is possible to shape the light beam L using a pre-designed diffraction grating pattern (i.e., to shape the light beam L so that the light projected onto the scanning area A becomes the desired deformed line beam Ld). The incident light beam L can be shaped by displacing each reflective element 62 so that a diffraction grating pattern) is formed by the plurality of reflective elements 62. That is, by forming a diffraction grating pattern for shaping the light beam L on the plurality of reflective elements 62, the planar light valve 6 can function as the shaping part 13b.

On the other hand, in the planar light valve 6, the incident light beam L is guided by displacing each reflective element 62 so that a blaze pattern for guiding the light beam L is formed by the plurality of reflective elements 62. The scanning area A can be guided to scan. That is, by forming a blaze pattern on the plurality of reflective elements 62 to guide the light beam L, the planar light valve 6 can also function as the light guiding section 12b.

Here, a mode in which a blaze pattern for guiding the light beam L is formed on the plurality of reflective elements 62 will be described. Now, in the planar light valve 6 provided in place of the grating light valve 5, the arrangement direction of the plurality of reflection elements 62 along the first direction Ax is referred to as the "row direction Px", and the arrangement direction of the plurality of reflection elements 62 along the second direction Ay. The arrangement direction of the elements 62 is referred to as a "column direction Py," and furthermore, a group of reflective elements 62 arranged in the same column is referred to as a reflective element group 620 (FIG. 11). As described above, in the planar light valve 6, the displacement amount of each of the plurality of reflection elements 62 is controlled by the signal from the control unit 3, so that the plurality of reflection elements 62 can form various modes. . For example, the planar light valve 6 can form a pattern in which the displacement amounts of the plurality of reflective element groups 620 are equally zero. At this time, the plane light valve 6 functions as a mirror, and the light beam L incident on the plane light valve 6 is specularly reflected. For example, the planar light valve 6 can also form a blaze pattern in which the amount of displacement of the plurality of reflective element groups 620 changes periodically along the row direction Px. Needless to say, in the planar light valve 6, a blaze pattern with an arbitrary blaze period and an arbitrary blaze angle can be formed. When the plurality of reflective element groups 620 form a blaze pattern along the arrangement direction, the planar light valve 6 functions as a blazed diffraction grating. That is, the planar light valve 6 at this time modulates the phase of the light beam L incident thereon and reflects the light beam L at an angle corresponding to the blaze period. Therefore, by successively changing the blaze period of the blaze pattern formed by the plurality of reflective element groups 620, it is possible to successively change the angle at which the light beam L is reflected from the planar light valve 6. In this way, by successively changing the direction in which the light beam L is emitted, the light beam L can be guided in the row direction Px (i.e., the first direction Ax) to scan the scanning area A. can.

Here, a diffraction grating pattern for shaping the light beam L (that is, a diffraction grating pattern that can shape the light beam L so that the light projected onto the scanning area A becomes the desired deformed line beam Ld) is used. ) and a blaze pattern for guiding the light beam L in the first direction Ax (needless to say, a blaze pattern whose blaze period changes one after another) are formed by the plurality of reflective elements 62. (Specifically, a control signal to be applied to each reflective element 62 is defined). Then, the light beam L incident on the planar light valve 6 is shaped according to the diffraction grating pattern and guided according to the blaze pattern. That is, the planar light valve 6 can function as the molded part 13b as well as the light guiding part 12b.

As described above, in the detection device 100b according to the second modification, the planar light valve 6, which is a two-dimensional spatial phase modulation element, is shared between the light guide section 12b and the shaping section 13b, and the planar light valve 6 is a two-dimensional spatial phase modulation element. 6 guides and shapes the light beam L. According to this configuration, the number of parts can be reduced and the device configuration can be simplified.

In the detection method performed by the detection device 100b according to this modification, a shaping step S13 in which the light beam L is shaped and a light guiding step S12 in which the light beam L is guided are performed in parallel.

Needless to say, when the planar light valve 6 is provided in place of the grating light valve 5 in the optical system (FIGS. 7 and 8) of the detection device 100 according to the above-described embodiment, appropriate adjustments may be made accordingly. changes may be made. For example, it is also preferable that optical components be added or changed so that the light beam L emitted from the light source 11 is spread in the first direction Ax and the second direction Ay and enters the flat light valve 6.

<4-3. Third modification>
As described above, in the planar light valve 6, the incident light beam L is diffracted according to the diffraction grating pattern formed by the plurality of reflection elements 62, so that the shape (shaped pattern) according to the diffraction grating pattern is formed. is formed into. Here, since each reflective element 62 is displaced according to a signal from the control section 3, by changing the signal given to each reflective element 62 from the control section 3, the shape formed by the plurality of reflective elements 62 can be changed. The diffraction grating pattern (and thus the shaping pattern applied to the light beam L) can be freely changed.

Therefore, for example, when the molded parts 13a and 13b are configured to include the planar light valve 6 (detecting devices 100a and 100b according to the first or second modification), each reflective element 62 included in the planar light valve 6 A pattern changing unit 301 may be provided that changes the diffraction grating pattern formed by the plurality of reflective elements 62 by changing the control signal provided. The pattern changing unit 301 is realized in the control unit 3 by, for example, the CPU 31 executing a program P stored in the storage device 34.

According to this configuration, the pattern changing unit 301 changes the diffraction grating pattern to change the arrangement pattern of the collimated beams C in the modified line beam Ld projected onto the scanning area A (specifically, for example, the number of collimated beams C, (spacing, beam diameter, profile, etc.) can be changed freely.

<4-3-1. Mode of change (1)>
For example, the pattern changing unit 301 may change the diffraction grating pattern so that one or more collimated beams C at the ends of the second direction Ay disappear in the modified line beam Ld projected onto the scanning area A. .

Specifically, for example, as shown in FIG. 13, the pattern changing unit 301 receives a designation of an area (region of interest) Ar narrower than the scanning area A from the user, and changes the area outside the designated area of interest Ar. The diffraction grating pattern may be changed so that the projected collimated beam C disappears. However, in FIG. 13, the modified line beam Ld' when the light beam L is shaped by the diffraction grating pattern before the change is shown by a two-dot chain line, and the light beam L is shaped by the diffraction grating pattern after the change. The deformed line beam Ld in this case is shown by a solid line.

In this way, in the deformed line beam Ld, by eliminating one or more collimated beams C at the end of the second direction Ay, the total number of collimated beams C included in the deformed line beam Ld decreases, and the remaining collimated beams The intensity of beam C increases. This makes it possible to further extend the measured distance. That is, for the region of interest Ar, which is narrower than the scanning area A, it is possible to achieve a longer measuring distance than the scanning area A.

<4-3-2. Modification mode (2)>
As described above, in the planar light valve 6, the incident light beam L is diffracted according to the diffraction grating pattern formed by the plurality of reflection elements 62, so that the shape (shaped pattern) according to the diffraction grating pattern is formed. When the arrangement pattern of the collimated beams C in this shaping pattern and the arrangement pattern of the collimated beams C in the deformed line beam Ld actually projected onto the scanning area A do not match (do not have a similar relationship). There is. One of the causes is the aberration (eg, distortion) of the lens (eg, wide-angle lens) included in the transmitter 1. That is, for example, even if the light beam L is shaped into a shaping pattern such that the interval between the collimated beams C is constant in the flat light valve 6, the shaped light beam L will be distorted by the lenses 103 and 104 (FIG. 7, In the deformed line beam Ld that is actually projected onto the scanning area A as a result of being projected onto the scanning area A through FIG. A situation may occur in which the distance becomes wider (if the lenses 103 and 104 have pincushion-shaped distortion) or narrowed (if the lenses 103 and 104 have barrel-shaped distortion).

Therefore, in the modified line beam Ld projected onto the scanning area A through the lenses (for example, lenses 103 and 104) included in the transmitting unit 1, the pattern changing unit 301 changes the shape so that the plurality of collimated beams C are arranged at equal intervals. , the diffraction grating pattern may be corrected by taking into account the aberration of the lens.

For example, in the flat light valve 6, when the light beam L is shaped into a shaping pattern such that the interval between the collimated beams C is constant, the shaped light beam L is projected onto the scanning area A through the lenses 103 and 104. At this time, due to the aberration of the lenses 103 and 104, in the deformed line beam Ld' projected onto the scanning area A, adjacent collimated beams C become closer to the end of the arrangement direction (second direction) Ay of the collimated beams C. Assume that the interval between the two has become wider (double-dashed line in FIG. 14). In this case, the pattern changing unit 301 takes into account the aberrations of the lenses 103 and 104, and shapes the light beam L into a shaped pattern such that the interval between adjacent collimated beams C narrows as it approaches the end in the arrangement direction of the collimated beams C. Correct the grating pattern so that it is shaped. Then, when the light beam L shaped into a shaped pattern according to the corrected diffraction grating pattern (corrected diffraction grating pattern) is projected onto the scanning area A through the lenses 103 and 104, the aberrations of the lenses 103 and 104 are Therefore, in the modified line beam Ld projected onto the scanning area A, a plurality of collimated beams C are arranged at equal intervals (solid lines in FIG. 14).

In many cases, the effect of the aberrations of the lenses 103, 104 increases as the light beam L approaches the edge of the guiding range (ie, as the absolute value of the scan angle increases). That is, as the end of the guidance range approaches, the amount of deviation between the arrangement pattern of the collimated beams C in the shaping pattern and the arrangement pattern of the collimated beams C in the modified line beam Ld projected onto the scanning area A through the lenses 103 and 104 becomes as follows. growing. Therefore, the corrected diffraction grating pattern for arranging a plurality of collimated beams C at equal intervals in the modified line beam Ld projected onto the scanning area A through the lenses 103 and 104 is determined by the guiding position of the light beam L (scanning angle). Therefore, a corrected diffraction grating pattern is designed in advance for each guiding position of the light beam L and stored in, for example, the storage device 34, and the pattern changing unit 301 guides the light beam L by the light guiding units 12 and 12b. In parallel with this, it is preferable to sequentially switch the diffraction grating patterns formed on the plurality of reflective elements 62 to corrected diffraction grating patterns designed for each guiding position. Thereby, it is possible to ensure that the modified line beam Ld projected onto the scanning area A is a plurality of collimated beams C arranged at equal intervals over the entire guiding range.

In this way, the pattern changing unit 301 corrects the diffraction grating pattern by taking into account the aberrations of the lenses 103 and 104 included in the transmitting unit 1, so that the projection onto the scanning area A due to the aberrations of the lenses 103 and 104 is corrected. In the deformed line beam Ld, the occurrence of a situation in which the interval between the plurality of collimated beams C widens (or narrows) as it approaches the end in the arrangement direction of the collimated beams C can be avoided. That is, the influence of aberrations of the lenses 104 and 105 can be reduced or eliminated (the aberrations can be corrected).

Note that the aberrations of the lenses 103 and 104 included in the transmitter 1 not only cause variations in the interval between the collimated beams C in the modified line beam Ld projected onto the scanning area A through these lenses, but also cause variations in the beam diameter of the collimated beams C. may also cause variations. Therefore, it is also preferable that the pattern changing unit 301 corrects the diffraction grating pattern so that the light beam L is shaped into a shaping pattern that reduces variations in beam diameter. That is, the pattern changing unit 301 changes the lens so that the beam diameters of the plurality of collimated beams C are equal to each other in the modified line beam Ld projected onto the scanning area A through the lenses 103 and 104 included in the transmitting unit 1. It is also preferable to correct the diffraction grating pattern by taking into account the aberrations.

<4-4. Fourth modification>
The arrangement pattern of the collimated beams C in the modified line beam Ld in which a plurality of collimated beams C are arranged (multi-spot collimated beams C) is not limited to that illustrated in the above embodiments.

FIG. 15 shows another example of the arrangement pattern of the collimated beams C. Like the modified line beam Ld1 shown here, the collimated beams C are arranged so that each collimated beam C is incident on a photodetector group 2110 consisting of a predetermined number (three in the example shown) of adjacent photodetectors 211. A pattern may be defined. Further, like the deformed line beam Ld2, each of the adjacent collimated beams C skips a predetermined number (one in the example shown) of photodetectors 211 and enters each photodetector 211 (that is, a predetermined number of photodetectors 211). The arrangement pattern of the collimated beams C may be defined such that the collimated beams C are incident on the photodetectors 211 at different intervals. In addition, like the modified line beam Ld3, each of the adjacent collimated beams C skips a predetermined number (one in the example shown) of the photodetectors 211, and skips the photodetector group 2110 (in the example shown, two adjacent ones). The arrangement pattern of the collimated beam C may be defined so that the collimated beam C is incident on a photodetector group 2110) consisting of photodetectors 211.

In any of these modified line beams Ld1, Ld2, and Ld3, the gap between the collimated beams C corresponds to the gap between the photodetectors 211. That is, by thinning out at least a portion of the light that was incident on the gap between the photodetectors 211 in the normal line beam Ln, the intensity of the light irradiated onto the scanning area A is increased, and the distance measurement is extended. Therefore, it is possible to extend the measured distance while suppressing a decrease in resolution.

<4-5. Other variations>
The configurations of the above-described embodiment and each of the above-described modifications are also merely examples, and these can be changed as appropriate.

For example, in the above-described embodiment and each of the above-described modifications, the position at which the light beam L is shaped (the position at which the phase distribution is imparted) can be changed as appropriate. That is, the position of the diffractive optical element 4 included in the molding section 13 according to the above embodiment or the position of the planar light valve 6 included in the molding section 13a according to the first modification can be changed as appropriate. Specifically, for example, the diffractive optical element 4 may be provided between the cylindrical lens 101 and the lens 102, or may be provided integrally with the grating light valve 5 or sufficiently close thereto. . Similarly, the planar light valve 6 may be provided between the cylindrical lens 101 and the lens 102, or may be provided integrally with the grating light valve 5 or sufficiently close thereto. When the diffractive optical element 4 serving as the molding part 13 or the plane light valve 6 serving as the molding part 13a is placed upstream of the grating light valve 5 serving as the light guiding part 12, A shaping step S13 in which the light beam L is shaped is performed before a light guiding step S12 in which the light beam L is guided.

For example, in the above embodiment, a diffraction grating pattern for shaping the light beam L is formed by a concave-convex structure on the reflective surface 521 of the ribbon 52 of the group of grating light valves 5 provided as the light guiding section 12 ( For example, it may be engraved). In this case, by displacing each ribbon 52 so that a blaze pattern (needless to say, a blaze pattern in which the blaze period changes one after another) for guiding the light beam L is formed by a plurality of ribbons 52, The light beam L incident on the grating light valve 5 can be guided according to the blaze pattern while being shaped according to the diffraction grating pattern. That is, the grating light valve 5 can function as the light guiding section 12 and also as the molding section 13.

Further, for example, in the above-described embodiment or each of the above-described modifications, the molding portions 13, 13a, and 13b may be configured using LCOS (Liquid Crystal On Silicon). Elcos is a type of two-dimensional spatial phase modulation element. In other words, the Elcos has a plurality of pixel electrodes as two-dimensionally arranged grating elements, forms a diffraction grating pattern by driving the plurality of pixel electrodes, and uses the diffraction grating pattern to direct the light beam L. Diffraction (apply phase modulation according to the diffraction grating pattern). Specifically, Elcos has a plurality of pixel electrodes arranged two-dimensionally (for example, in a matrix) on a CMOS chip, a transparent electrode provided on a glass substrate, etc., and a transparent electrode between each pixel electrode. The liquid crystal is sealed between the electrode and the liquid crystal. In such a configuration, when a voltage is applied to each of the plurality of pixel electrodes, the liquid crystal is displaced (tilted) in accordance with the applied voltage, and the refractive index changes. Therefore, various modes (patterns) can be formed by controlling the voltage applied to each pixel electrode. In other words, in L-COS, by controlling the amount of displacement of the liquid crystal corresponding to each pixel electrode using a signal from the control unit 3, the same pattern as that of the diffraction grating pattern formed in the diffraction optical element 4 according to the above embodiment is formed. A diffraction grating pattern can be formed, and by diffracting the incident light beam L according to the diffraction grating pattern (giving a phase distribution according to the diffraction grating pattern), It can be molded into any shape (molding pattern). In other words, by defining the control signals given to each pixel electrode so that a diffraction grating pattern designed according to the desired shaping pattern is formed, the light beam L can be shaped into the desired shaping pattern. .

Further, the manner in which the diffraction grating pattern is changed in the pattern changing unit 301 is not limited to the example illustrated above. For example, as illustrated above, the pattern changing unit 301 may change the diffraction grating pattern so as to reduce the number of collimated beams C in the modified line beam Ld projected onto the scanning area A, or conversely, The diffraction grating pattern may be changed to increase the number of collimated beams C. Further, the pattern changing unit 301 may change the diffraction grating pattern so as to widen or narrow the interval between the collimated beams C. Further, the pattern changing unit 301 may change the diffraction grating pattern so as to increase or decrease the beam diameter of the collimated beam C. Needless to say, these modes of changing the diffraction grating pattern may be combined as appropriate.

Further, for example, in the above embodiment or each of the above modifications, the detection devices 100, 100a, 100b are provided with an optical isolator between the light source 11 and the light guiding portions 12, 12b to block returning light. It's okay to be hit. Further, for example, a band-pass filter or the like is provided before the photodetector 21 to attenuate unnecessary frequency bands (for example, frequency bands other than the frequency band of the light beam L emitted from the light source 11) and A frequency band (for example, a frequency band of the light beam L emitted from the light source 11) may be passed through and input to the photodetector 21. Further, the control unit 3 may include a TDC (Time to Digital Converter).

Further, for example, in the above embodiment or each of the above modifications, the projection optical system of the transmitter 1 is configured so that the projection optical system of the transmitter 1 is configured so that light is emitted from the light guide parts 12 and 12b (specifically, the grating light valve 5 or the planar light valve 6). It may also have a function of increasing the reflection angle of the beam L to widen the guiding range (scanning angle range) of the light beam L. This function can be realized, for example, by focusing the 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, for example, the diffractive optical element 4 included in the shaping unit 13 according to the embodiment described above may generate a plurality of It may have a diffraction grating pattern that takes into account the aberration of the lens so that the collimated beams C are arranged at equal intervals. As mentioned above, the corrected diffraction grating pattern for arranging a plurality of collimated beams C at equal intervals in the modified line beam Ld projected onto the scanning area A through the lens is determined by the guiding position of the light beam L (scanning angle ). Here, the position where the light beam L is incident on the diffractive optical element 4 changes depending on the guiding position of the light beam L. Therefore, for each guide position of the light beam L, the position on the diffractive optical element 4 where the light beam L is incident, and the position on the diffractive optical element 4 in order to cancel the influence of the aberration of the lenses 103 and 104 at the guide position. A corrected diffraction grating pattern to be formed at a position may be determined in advance, and a diffraction grating pattern having a corrected diffraction grating pattern corresponding to the position at each position may be formed on the diffractive optical element 4. Even with such a configuration, due to the aberrations of the lenses 103 and 104, in the deformed line beam Ld projected onto the scanning area A, the interval between the plurality of collimated beams C becomes smaller as the distance between the collimated beams C approaches the end in the arrangement direction of the collimated beams C. Expansion (or narrowing) can be suppressed.

Further, for example, in the transmitter 1 according to the above embodiment or each of the above modifications, a polarizing beam splitter and a quarter wavelength plate may be further provided. Specifically, for example, the light beam L emitted from the lens 102 is bent at right angles by a polarizing beam splitter, passed through a quarter-wave plate, and then passed through the light guide portions 12, 12b (specifically, The light beam L that is incident on the grating light valve 5 or the planar light valve 6) and reflected by the light guiding parts 12 and 12b is passed through the quarter-wave plate again and then sent to the polarizing beam splitter. It may also be configured such that the light is incident. In this case, the light beam L is rotated by 1/4 wavelength as it passes through the 1/4 wavelength plate for the first time, and then enters the light guide portions 12 and 12b 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 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. .

Further, for example, the light detection section 21 of the reception section 2 according to the above-described embodiment or each of the above-described modifications may include, for example, a two-dimensional photodetector array in which photodetectors 211 are arranged two-dimensionally.

Further, the functions and operations of the control unit 3 according to the above-described embodiment or each of the above-described modifications are merely examples, and can be changed as appropriate. For example, the method by which the control unit 3 acquires the measurement data does not necessarily have to be the ToF method, and may be, for example, a frequency modulation continuous wave (FMCW) method, an AMCW method, or the like. For example, when adopting the FMCW method, the light source 11 generates and emits a light beam whose wavelength changes continuously. Then, the light beam reflected by the object At in the scanning area A is branched from a reference light beam (for example, before the light beam emitted from the light source 11 is irradiated to the scanning area A). The distance to the object At may be calculated based on the beat signal included in the resulting composite wave. Further, for example, the measurement data acquired by the control unit 3 may be one of the distance to the target object At and the position of the target object At, or various other data (for example, the speed of the target object At). , acceleration) may be acquired as the measurement data.

As mentioned above, although the detection device and the detection method have been explained in detail, the above explanations are illustrative in all aspects and are 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, 100a, 100b Detection device 1 Transmitter 11 Light source 12, 12b Light guiding section 13, 13a, 13b Molding section 2 Receiving section 21 Photodetector 211 Photodetector 3 Control section 301 Pattern changing section 4 Diffractive optical element 5 Grating light valve 6 Planar light valve (two-dimensional spatial phase modulation element)
Ld Deformed line beam C Collimated beam

Claims (10)

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 light source that emits light;
a light guide unit that modulates the phase of the light to guide the light in a first direction to scan the scanning area;
a shaping unit that shapes the light so that the light projected onto the scanning area becomes a deformed line beam in which a plurality of collimated beams are arranged with gaps provided along a second direction intersecting the first direction; and,
A detection device comprising: The detection device according to claim 1,
The receiving section,
a photodetecting section in which a plurality of photodetectors are arranged along the second direction;
Equipped with
A gap between the collimated beams is configured to correspond to a gap between the photodetectors.
Detection device. The detection device according to claim 2,
Each of the adjacent collimated beams in the deformed line beam is configured to be incident on each of the adjacent photodetectors in the photodetection section,
Detection device. The detection device according to any one of claims 1 to 3,
The molding part is
A diffractive optical element with a diffraction grating pattern formed by a concavo-convex structure,
Equipped with
shaping the light by diffracting the light with the diffraction grating pattern;
Detection device. The detection device according to any one of claims 1 to 3,
The molding part is
a two-dimensional spatial phase modulation element having a plurality of grating elements arranged two-dimensionally, and forming a diffraction grating pattern by driving each of the plurality of grating elements;
Equipped with
shaping the light by diffracting the light with the diffraction grating pattern;
Detection device. 6. The detection device according to claim 5,
The two-dimensional spatial phase modulation element is shared between the light guide section and the shaping section, and the two-dimensional spatial phase modulation element guides the light and shapes the light.
Detection device. 6. The detection device according to claim 5,
In the two-dimensional spatial phase modulation element, a pattern changing unit that changes a diffraction grating pattern formed by the plurality of grating elements;
A detection device comprising: 8. The detection device according to claim 7,
The pattern changing section
changing the diffraction grating pattern so that one or more collimated beams at an end in the second direction disappear in the modified line beam projected onto the scanning area;
Detection device. 8. The detection device according to claim 7,
The pattern changing section
In the modified line beam projected onto the scanning area through a lens included in the transmitter, the diffraction grating pattern is corrected by taking into account aberrations of the lens so that the plurality of collimated beams are arranged at equal intervals. ,
Detection device. 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:
an emission step of emitting light;
a light guiding step of guiding the light in a first direction to scan the scanning area by modulating the phase of the light;
Before the light guiding step, after the light guiding step, or in parallel with the light guiding step, the light projected onto the scanning area is transmitted in a plurality of directions along a second direction intersecting the first direction. a shaping process of shaping the light so that the collimated beams become a deformed line beam arranged with gaps;
A detection method comprising:

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