Optical scanner and object detection device

Abstract

To make a measurement field-of-view angle wider.SOLUTION: An optical scanner, which is used in a device radiating light and receiving reflection light of the radiated light to perform object detection, includes: a deflector; a light source that has at least a first light emitting unit emitting first light, and a second light emitting unit emitting second light different in optical characteristic from the first light; a first optical element that is arranged so that the first light emitted from the first light emitting unit is incident, and reflects the first light to make the reflected first light incident upon the deflector; and a second optical element that is arranged so that the second light emitted from the second light emitting unit is incident, and reflects the second light to make the reflected second light incident upon the deflector. The first optical element has an optical characteristic that reflects the first light and transmits the second light, and the second optical element has an optical characteristic that reflects the second light and transmits the first light.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to an optical scanning device and an object detection device.

Background Art

[0002] Conventional examples of an optical scanning device and an object detection device are described in, for example, Japanese Patent Application Laid-Open No. 2010-151958 (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] One of the objects of specific aspects according to the present disclosure is to widen the measurement field angle in an optical scanning device or the like.

Means for Solving the Problems

[0005] [1] An optical scanning device according to one aspect of the present disclosure is an optical scanning device used in a device that performs object detection by irradiating light and receiving the reflected light thereof, a deflector, a light source having at least a first light emitting unit that emits first light and a second light emitting unit that emits second light having optical characteristics different from those of the first light, a first optical element that is arranged so that the first light emitted from the first light emitting unit is incident thereon, and reflects the first light and makes it incident on the deflector, a second optical element that is arranged so that the second light emitted from the second light emitting unit is incident thereon, and reflects the second light and makes it incident on the deflector, and includes the first optical element has an optical characteristic of reflecting the first light and transmitting the second light, The second optical element has an optical property of reflecting the second light and transmitting the first light. It is a light scanning device. [2] An object detection device according to one aspect of the present disclosure is the light scanning device described in [1] above, a light receiving unit that detects reflected light from the irradiation light emitted from the light scanning device and generates a light receiving signal according to the intensity of the reflected light, a control unit that controls the operation of the light scanning device and generates point cloud information based on the light receiving signal, and includes an object detection device.

[0006] According to the above configuration, the measurement field of view angle in the light scanning device and the object detection device including the same can be made wider.

Brief Description of Drawings

[0007]

Figure 1

Figure 2

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[0008] FIG. 1 is a diagram showing the configuration of an object detection device according to an embodiment. The object detection device according to this embodiment uses a plurality of laser beams (detection light) to perform optical scanning on a target space, receives the reflected light, and detects point cloud information indicating the position, relative distance, etc. of an object existing in the target space using the reflected light. It includes a controller 1, a scanning light source unit (optical scanning device) 2, and a light receiving unit 3. This object detection device is used, for example, when mounted on a vehicle to detect objects (other vehicles, pedestrians, etc.) around the vehicle. In this case, the object detection device can be arranged, for example, on the roof of the vehicle, near the emblem, near the rearview mirror, inside the headlamp, etc.

[0009] The controller 1 controls the overall operation of the object detection device and includes a measurement control unit 10, a deflection control unit 11, a lighting control unit 12, a distance measurement unit 13, and a communication unit 14. This controller 1 can be realized, for example, by using a computer system equipped with a CPU, ROM, RAM, etc. and causing the computer system to execute a predetermined operation program.

[0010] The measurement control unit 10 controls the operation of the deflection control unit 11, the lighting control unit 12, and the distance measurement unit 13, and controls the communication unit 14 to transmit the point cloud information, which is the measurement result of the distance measurement unit 13, to an external device (not shown).

[0011] The deflection control unit 11 controls, via the MEMS driver 20 of the scanning light source unit 2, the MEMS mirror 22 to be periodically deflected at an instructed angle change pattern (typically a raster scan with equal scanning line intervals).

[0012] The lighting control unit 12 controls the light source driver 21 so that the light source LS emits laser light under the pulse conditions instructed by the measurement control unit 10.

[0013] The distance measurement unit 13 measures the distance to an object in the target space based on the time difference between the laser light emission time and the light reception time using the laser light generation instruction timing by the lighting control unit 12 and the light reception signal obtained from the light reception circuit 33 of the light reception unit 3. Also, the three-dimensional position of the object is detected by the measurement control unit 10 based on the laser light emission time and the light reception time.

[0014] The communication unit 14 transmits the obtained point cloud information (a set of three-dimensional positions) to an external device (not shown).

[0015] The scanning light source unit 2 generates a narrow-angle beam of laser light and emits the laser light in various directions within a predetermined range, and is configured to include an MEMS driver 20, a light source driver 21, an MEMS mirror 22, a light source LS, and a dichroic mirror R.

[0016] The MEMS driver 20 is connected to the MEMS mirror 22, receives control by the deflection control unit 11 of the controller 1, generates a drive signal for controlling the operation of the MEMS mirror 22, and supplies the drive signal to the MEMS mirror 22.

[0017] The light source driver 21 is connected to the light source LS, generates a drive signal for controlling the operation of the light source LS under the control of the lighting control unit 12 of the controller 1, and supplies the drive signal to the light source LS.

[0018] The MEMS mirror 22 has a reflecting surface and is a deflector configured to be rotatable in each of two orthogonal directions. The MEMS mirror 22 is disposed at a position where the laser light emitted from the light source LS can be incident on the reflecting surface from different directions, and rotates based on the drive signal supplied from the MEMS driver 20 to scan each laser light within the target space. Each laser light is emitted from an opening 23 appropriately provided in the scanning light source unit 2 to the external target space.

[0019] The light source LS is configured to include a plurality of light emitting units, and based on the control signal from the lighting control unit 12 respectively, generates a plurality of laser lights of narrow-angle beams (beams with a small divergence angle) as detection light, and emits each of the laser lights (pulse light). For example, the plurality of light emitting units are each a laser diode element. The laser light emitted from each light emitting unit of the light source LS is a beam having a divergence angle that conforms to (is the same as or less than) the angular resolution of the object detection device. As each light emitting unit of the light source LS, for example, a near-infrared photonic crystal laser (PCSEL) can be used, but it is not limited thereto, and any light source LS capable of emitting detection light of a narrow-angle beam may be used.

[0020] The plurality of light emitting units included in the light source LS include a first light emitting unit having predetermined optical characteristics and a second light emitting unit having optical characteristics different from those of the first light emitting unit. For example, the first light emitting unit and the second light emitting unit may have different emission wavelengths, or may have different polarization directions. The light source LS of the present embodiment includes two first light emitting units and two second light emitting units having different emission wavelengths respectively.

[0021] The light receiving unit 3 receives the reflected light generated by each laser beam emitted from the light source LS and generates a light reception signal, and includes a lens 30, an optical filter 31, a photodetector (light receiving element) 32, and a light receiving circuit 33. The light receiving unit 3 may be configured as a coaxial optical system that receives light on the same optical path as the optical path from the light source LS to the MEMS mirror 22, or may be configured as a non-coaxial optical system that does not use the same optical path.

[0022] The lens 30 condenses the reflected light generated by the laser beam emitted from the light source LS. The optical filter 31 blocks light in a wavelength range different from that of the laser beam emitted from the light source LS and transmits light in the same wavelength range as the laser beam emitted from the light source LS. The photodetector 32 detects the light incident through the optical filter 31.

[0023] The light receiving circuit 33 generates a light reception signal by performing predetermined signal processing (such as amplification, frequency filtering, etc.) on the output of the photodetector 32. The generated light reception signal is supplied to the distance measurement unit 13 of the controller 1.

[0024] FIG. 2 is a diagram for explaining an example of the layout inside the housing of the scanning light source unit. In the illustrated configuration example of the scanning light source unit 2, inside the housing, a substrate on which the MEMS driver 20 and the MEMS mirror 22 are mounted is arranged on the side surface in the figure, a substrate on which the light source driver 21 and the light source LS are mounted is arranged on the bottom surface in the figure, and each dichroic mirror R is arranged obliquely on the side surface at a position facing the MEMS mirror 22. The MEMS driver 20 does not necessarily have to be on the same substrate as the MEMS mirror 22, and although the housing size increases, it may be separate. An opening through which the light reflected by the MEMS mirror 22 and emitted from the scanning light source unit 2 passes is formed in the housing. The housing is made of, for example, aluminum. Preferably, the housing is subjected to black anodizing to prevent noise due to external light and the like. Each substrate is fixed to the housing by, for example, screwing. The dichroic mirror R is fixed to the housing by, for example, adhesion.

[0025] The light source LS includes a plurality of light emitting parts LS1, LS2, LS3, LS4 arranged in the depth direction of the paper surface. The dichroic mirror R includes a plurality of dichroic mirrors R1, R2, R3, R4 arranged in the depth direction of the paper surface. Each of the dichroic mirrors R1, R2, R3, R4 is arranged at a position where any of the laser lights emitted from each light emitting part of the light source LS can be incident. The MEMS mirror 22 is arranged at a position where the laser light incident on and reflected by each of the dichroic mirrors R1, R2, R3, R4 can be incident. Specifically, the light source LS and each of the dichroic mirrors R1, etc. are arranged such that the laser light emitted from each light emitting part LS1, etc. of the light source LS is emitted in the Y direction in the figure and is incident on any of the dichroic mirrors R1, etc. Each of the dichroic mirrors R1, etc. is arranged at a position and an angle such that the incident light from each light emitting part LS1, etc. is reflected and incident on the MEMS mirror 22. Also, each of the dichroic mirrors R1, etc. is arranged at a position where any of the light reflected by the MEMS mirror 22 is incident. Therefore, a part of each of the dichroic mirrors R1, etc. is arranged so as to cover the opening of the housing. Also, the MEMS mirror 22 is arranged such that the laser light reflected by each of the dichroic mirrors R1, etc. travels in the Z direction in the figure, that is, in the direction of the opening of the housing and is incident.

[0026] The laser light can be scanned by swinging the MEMS mirror 22. For example, the laser light traveling in the Z direction shown in the figure is scanned so as to move up and down in the Y direction. The locus of the laser light becomes the irradiation area. A part of the irradiation area includes the positions of the dichroic mirrors R1, etc. as shown in the figure. The light reflected by the MEMS mirror 22 and incident on the dichroic mirrors R1, etc. passes through the dichroic mirrors R1, etc. and travels from inside the housing of the scanning light source unit 2 to the outside. When passing through the inside of the dichroic mirrors R1, etc., the laser light is refracted inside, causing the optical path to deviate from before incidence. However, since the deviation of this optical path is about the thickness of the dichroic mirrors R1, etc., it has no influence on the distance measurement performance and can be corrected on the light receiving part 3 side.

[0027] Here, each of the dichroic mirrors R1, R2, R3, and R4 is composed of a thin film of a high-refractive-index member such as titanium oxide, tantalum oxide, or niobium oxide, and a thin film of a low-refractive-index member such as silicon oxide or magnesium fluoride, which are laminated in several layers to several hundred layers on, for example, a glass substrate based on a predetermined optical design. In the present embodiment, each of the dichroic mirrors R1, etc. is configured by laminating the above-mentioned thin films on a glass substrate, and is configured to have a size of, for example, about 3 mm on the short side, about 8 mm on the long side, and about 1 mm in thickness. Then, a portion about 3 to 4 mm along the long side direction is adhered and fixed to an inclined surface provided at a position facing the MEMS mirror 22 inside the housing of the scanning light source unit 2, and the remaining portion not fixed to this inclined surface is arranged to hang down from the inclined surface. For adhering the dichroic mirrors R1, etc., for example, a photocurable resin or a thermosetting resin can be used.

[0028] Figure 3 is a diagram for explaining in detail the arrangement of each dichroic mirror and the MEMS mirror. In the figure, in order from the upper row, an arrangement diagram in YZ coordinates, an arrangement diagram in XY coordinates, an arrangement diagram in XZ coordinates, and a perspective view are shown. The Y-axis and Z-axis mentioned here correspond to each axis in FIG. 2 above, and the X-axis corresponds to a direction orthogonal to each of the Y-axis and Z-axis in FIG. 2 above. Also, "before driving" indicates the trajectory of the laser light incident on and reflected by each of the dichroic mirrors R1, etc. when the MEMS mirror 22 is at the reference position with a horizontal mechanical angle (swing angle) of 0° and a vertical mechanical angle (swing angle) of 0°, and "after driving" indicates the trajectory of the laser light incident on and reflected by each of the dichroic mirrors R1, etc. when the MEMS mirror 22 has the maximum mechanical angle in the present embodiment, that is, a horizontal mechanical angle (swing angle) of 8° and a vertical mechanical angle (swing angle) of 5°. Also, hereinafter, the four light-emitting portions of the light source LS are distinguished as LS1, LS2, LS3, and LS4, respectively. Each light-emitting portion LS1, etc. exists below each of the dichroic mirrors R1, etc. on the paper surface (not shown, only the reference numerals are shown).

[0029] As shown in the layout diagrams in the XY coordinates and the layout diagrams in the XZ coordinates, the dichroic mirrors R1 to R4 are arranged at intervals along the X direction. The laser light emitted from each light emitting unit LS1 to LS4 is emitted from below the dichroic mirrors R1 etc. in the diagrams in the XY coordinates and the YZ coordinates, enters the dichroic mirrors R1 etc., and enters the MEMS mirror 22. The MEMS mirror 22 is arranged deeper than the dichroic mirrors R1 etc. in the XY coordinates and is arranged relatively on the left side with respect to the dichroic mirrors R1 etc. in the YZ coordinates.

[0030] The laser light reflected by the MEMS mirror 22 may pass through each dichroic mirror R1 etc. or may pass through the gaps between the dichroic mirrors R1 etc. The former is shown in the layout diagram of the XZ coordinates "before driving", and the latter is shown in the layout diagram of the XZ coordinates "after driving". When the MEMS mirror 22 is swung, the laser light enters and passes through each dichroic mirror R1 etc. up to a certain angle of swing angle, and the laser light passes through the gaps between the dichroic mirrors R1 etc. at a swing angle after a certain angle. The reason why the laser light passes through each dichroic mirror R1 etc. will be described below.

[0031] Figs. 4(A) and 4(B) are diagrams for explaining in more detail the relationship between each dichroic mirror and the trajectory of the laser light when the laser light passes through each dichroic mirror. Fig. 5 is a diagram showing an example of a combination of the transmission / reflection characteristics of each dichroic mirror and the wavelength of each light emitting unit. In the present embodiment, for example, four combinations shown in Fig. 5 are conceivable. In this case, it is a combination in which the light emitting unit LS1 and the light emitting unit LS4 form a pair, and a combination in which the light emitting unit LS2 and the light emitting unit LS3 form a pair. The wavelengths of the light emitting units LS1 etc. are examples and are not limited thereto, but it is more preferable that there is a difference of 50 nm or more in each combination. Hereinafter, the combination example No. 1 shown in Fig. 5 will be described.

[0032] As shown by the dotted line in Fig. 4(A), the laser light (first light) with a wavelength of 900 nm emitted from the light-emitting unit LS1 is incident on the dichroic mirror R1 having reflection characteristics for wavelengths of 900 nm or less and is reflected. After being reflected by the MEMS mirror 22, it passes through the dichroic mirror R4 having reflection characteristics for wavelengths of 950 nm or less and transmission characteristics for a wavelength of 900 nm, and is irradiated outside the scanning light source unit 2.

[0033] As shown by the dotted line in Fig. 4(B), the laser light (second light) with a wavelength of 950 nm emitted from the light-emitting unit LS4 is incident on the dichroic mirror R4 having reflection characteristics for wavelengths of 950 nm or less and is reflected. After being reflected by the MEMS mirror 22, it passes through the dichroic mirror R1 having reflection characteristics for wavelengths of 900 nm or less and transmission characteristics for wavelengths of 950 nm or more, and is irradiated outside the scanning light source unit 2.

[0034] The relationship between the light-emitting unit LS2 and the dichroic mirror R2 is the same. The laser light with a wavelength of 900 nm emitted from the light-emitting unit LS2 is incident on the dichroic mirror R2 having reflection characteristics for wavelengths of 900 nm or less and is reflected. After being reflected by the MEMS mirror 22, it passes through the dichroic mirror R3 having reflection characteristics for wavelengths of 950 nm or less and transmission characteristics for wavelengths of 900 nm or less, and is irradiated outside the scanning light source unit 2.

[0035] The relationship between the light-emitting unit LS3 and the dichroic mirror R3 is the same. The laser light with a wavelength of 950 nm emitted from the light-emitting unit LS3 is incident on the dichroic mirror R3 having reflection characteristics for wavelengths of 950 nm or less and is reflected. After being reflected by the MEMS mirror 22, it passes through the dichroic mirror R2 having reflection characteristics for wavelengths of 900 nm or less and transmission characteristics for wavelengths of 950 nm or less, and is irradiated outside the scanning light source unit 2.

[0036] FIG. 6 is a diagram showing an example of optically calculating a measurement field angle on the premise of the optical scanning device of the above-described embodiment. Each point shown in the figure indicates a measurement point obtained using each of the light emitting units LS1 and the like. When optical calculations were performed on the MEMS mirror 22 with a horizontal mechanical angle of ±8° and a vertical mechanical angle of ±5°, it was found that a measurement field angle of ±60° in the horizontal direction and ±6° in the vertical direction can be ensured as shown in the figure. According to this calculation result, it was found that the measurement field angle can be widened while reducing the vertical mechanical angle as compared with the conventional case. In the figure, the measurement points based on LS1 are indicated by black circles, the measurement points based on LS2 are indicated by white circles, the measurement points based on LS3 are indicated by black squares, and the measurement points based on LS4 are indicated by white squares. Further, the measurement points based on each light emitting unit show only those along the horizontal axis and the horizontal axis at the outer edge of the measurement range and at the center of the measurement range.

[0037] According to the above-described embodiment, it becomes possible to widen the measurement field angle in an optical scanning device or the like.

[0038] Note that the present disclosure is not limited to the content of the above-described embodiment, and various modifications can be made and implemented within the scope of the gist of the present disclosure. For example, in the above-described embodiment, a dichroic mirror is shown as an example of an optical element for performing wavelength filtering, but a band-pass filter may be used instead of this optical element or in combination with the dichroic mirror. For example, a band-pass filter with a transmission band of 25 nm that transmits wavelengths of 900 nm ± 12.5 nm and reflects other wavelength ranges, or a band-pass filter with a transmission band of 25 nm that transmits wavelengths of 950 nm ± 12.5 nm and reflects other wavelength ranges can be used.

[0039] Further, in the above-described embodiment, the light source LS is arranged so that the laser light emitted from the light source LS travels along the Y direction, but the arrangement of the light source LS is not limited to this. For example, the substrate on which the light source LS is mounted may be rotated and arranged in the X direction. In this case, the arrangement of each dichroic mirror R1 and the like may be adjusted so that the laser light is incident along the normal direction (Z direction) of the MEMS mirror 22.

[0040] Also, in the above-described embodiment, the MEMS mirror 22 was arranged such that the inclination of the MEMS mirror 22 in the initial state was 0° with respect to the Y-axis. However, the MEMS mirror 22 may be arranged with an inclination of up to about 5° with respect to the Y-axis. In this case, the positions of the dichroic mirrors R1 and the like may be adjusted so that the laser light reflected by the MEMS mirror 22 with a swing angle of 0° travels parallel to the Z direction.

[0041] Also, in the above-described embodiment, a configuration using a dichroic mirror as an example of the optical element has been described. However, the same operational effects can be obtained by using a reflective polarizing plate as the optical element. As the reflective polarizing plate mentioned here, for example, a polarizing beam splitter or a wire grid type polarizing plate can be used. In this case, the reflective polarizing plate may be arranged at the positions where the dichroic mirrors R1 and the like were arranged in the above-described embodiment. Also, in this case, as each light emitting unit LS1 of the light source LS, those capable of emitting laser light with a high degree of polarization and substantially linearly polarized light are used. As an example, an end face type laser diode showing a high degree of polarization with an s-wave component of 90% or more can be used. The basic configuration of the scanning light source unit 2 of this modified embodiment 1 is the same as the configuration shown in FIGS. 1 and 2, and only the points that the dichroic mirrors R1 and the like are replaced with reflective polarizing plates and that each light emitting unit LS1 and the like are replaced with those having a high degree of polarization are different, so the illustration of the basic configuration is omitted.

[0042] FIG. 7(A) and FIG. 7(B) are diagrams for explaining in more detail the relationship between each reflective polarizing plate and the trajectory of the laser beam when the laser beam passes through each reflective polarizing plate in Modification Example 1. FIG. 8 is a diagram showing an example of a combination of the transmission / reflection characteristics of each reflective polarizing plate and the wavelength of each light emitting part in Modification Example 1. In this Modification Example 1, for example, four combinations shown in FIG. 8 are conceivable. In this case, a combination in which the light emitting part LS1 and the light emitting part LS4 form a pair having polarization directions different by approximately 90°, and a combination in which the light emitting part LS2 and the light emitting part LS3 form a pair having polarization directions different by approximately 90°. The deflection directions (s-wave / p-wave) of each light emitting part LS1, etc. are examples and are not limited thereto.

[0043] Each of the reflective polarizing plates R11, R12, R13, and R14 is replaced with each of the dichroic mirrors R1, R2, R3, and R4 in the above-described embodiment. Each of the reflective polarizing plates R11, etc. is configured to have a size of, for example, about 3 mm on the short side, about 8 mm on the long side, and about 1 mm in thickness. When each of the reflective polarizing plates R11, etc. is a polarizing beam splitter, for example, it is configured by laminating a dielectric multilayer film on a glass substrate or the like. When it is a wire grid type, for example, it is configured by providing a wire grid made of a metal such as aluminum on one surface of a glass substrate or the like. Then, similar to the above-described embodiment, a portion about 3 to 4 mm along the long side direction is adhered and fixed to an inclined surface provided at a position facing the MEMS mirror 22 in the housing of the scanning light source unit 2, and the remaining portion not fixed to this inclined surface is arranged so as to hang down from the inclined surface. When the reflective polarizing plate R11, etc. is configured by a polarizing beam splitter, the reflective polarizing plate R11, etc. is arranged to be inclined so that the laser light emitted from each light emitting part LS1, etc. of the light source LS is incident at approximately 45°. For the adhesion of the reflective polarizing plate R11, etc., for example, a photocurable resin or a thermosetting resin can be used.

[0044] When the laser light is scanned by oscillating the MEMS mirror 22, part of the irradiation area includes the positions of the reflective polarizing plate R11 and the like, similar to the above-described embodiment. The light reflected by the MEMS mirror 22 and incident on the reflective polarizing plate R11 and the like passes through the reflective polarizing plate R11 and the like and travels from inside the housing of the scanning light source unit 2 to the outside. When passing through the inside of the reflective polarizing plate R11 and the like, the laser light is refracted inside, causing the optical path to shift from before incidence. However, since this shift of the optical path is about the thickness of the reflective polarizing plate R11 and the like, it has no effect on the ranging performance and can be corrected on the light receiving unit 3 side.

[0045] Hereinafter, the operation of the scanning light source unit 2 of the first modified embodiment will be described by taking the No. 1 combination shown in FIG. 8 as an example. However, the concept is the same for the combinations of No. 2 to No. 4.

[0046] As shown by the dotted line in FIG. 7(A), the s-wave laser light (first light) emitted from the light emitting unit LS1 is incident on the reflective polarizing plate R11 having reflection characteristics with respect to the s-wave, reflected, and after being reflected by the MEMS mirror 22, passes through the reflective polarizing plate R14 having transmission characteristics with respect to the s-wave and is irradiated to the outside of the scanning light source unit 2.

[0047] Also, as shown by the dotted line in FIG. 7(B), the p-wave laser light (second light) emitted from the light emitting unit LS4 is incident on the reflective polarizing plate R14 having reflection characteristics with respect to the p-wave, reflected, and after being reflected by the MEMS mirror 22, passes through the reflective polarizing plate R11 having transmission characteristics with respect to the p-wave and is irradiated to the outside of the scanning light source unit 2.

[0048] The relationship between the light emitting unit LS2 and the reflective polarizing plate R12 is the same. The s-wave laser light emitted from the light emitting unit LS2 is incident on the reflective polarizing plate R12 having reflection characteristics with respect to the s-wave, reflected, and after being reflected by the MEMS mirror 22, passes through the reflective polarizing plate R13 having transmission characteristics with respect to the s-wave and is irradiated to the outside of the scanning light source unit 2.

[0049] The relationship between the light-emitting unit LS3 and the reflective polarizing plate R13 is the same. The p-wave laser light emitted from the light-emitting unit LS3 is incident on the reflective polarizing plate R13 having reflection characteristics for the p-wave and is reflected. After being reflected by the MEMS mirror 22, it passes through the reflective polarizing plate R12 having transmission characteristics for the p-wave and is irradiated outside the scanning light source unit 2.

[0050] Also, with respect to the configuration of the above-described modified Example 1, it is also possible to provide an optical scanning device of a modified Example 2 in which a quarter-wave plate is further combined. The quarter-wave plate here is a wave plate capable of converting incident linearly polarized light into circularly polarized light or converting incident circularly polarized light into linearly polarized light. The configuration of the scanning light source unit 2 of this modified Example 2 is a configuration (configuration of modified Example 1) in which the dichroic mirror R1 and the like are replaced with reflective polarizing plates and each light-emitting unit LS1 and the like are replaced with those having a high degree of polarization in the configurations shown in FIGS. 1 and 2. As shown in the layout example in the housing of the scanning light source unit in FIG. 9, the quarter-wave plates T (T1, T2, T3, T4) are arranged so as to be interposed between the reflective polarizing plate R and the MEMS mirror 22. In the illustrated example, the quarter-wave plate T is adhesively fixed to the upper part of the housing and is arranged to hang down. For the adhesion of the quarter-wave plate T, for example, a photocurable resin or a thermosetting resin can be used.

[0051] The reflective polarizing plate R in this modified Example 2 is configured to have a size of, for example, about 1 mm on the short side, about 8 mm on the long side, and about 1 mm in thickness, and a portion of about 3 to 4 mm in the long side direction is adhesively fixed to the housing. The quarter-wave plate T is also configured to have the same size as the reflective polarizing plate R. The reason why both the reflective polarizing plate R and the quarter-wave plate T have a small lateral width (short side) is that when deflected by the MEMS mirror 22, the incident angle of the laser light when incident on the reflective polarizing plate R and the quarter-wave plate T changes, causing the polarization direction of the laser light to shift and making it difficult to polarize with the reflective polarizing plate R. Therefore, it is to reduce the incidence of laser light with such a large incident angle on the reflective polarizing plate R and the like.

[0052] FIGS. 10(A) to 10(D) are diagrams for more detailed explanation of the relationship between each reflective polarizing plate in Modified Example 2 and the trajectory of the laser light when the laser light passes through each reflective polarizing plate. FIG. 11 is a diagram showing an example of a combination of the transmission / reflection characteristics of each reflective polarizing plate and the wavelength of each light-emitting part in Modified Example 2. In this Modified Example 2, for example, two combinations shown in FIG. 11 are conceivable. In this case, the light-emitting parts LS1 to LS4 may all emit s-wave laser light of one type, and the reflective polarizing plates R11 to R14 may all have the characteristic of transmitting p-waves of one type.

[0053] Hereinafter, the operation of the scanning light source unit 2 of this Modified Example 2 will be described taking the combination No. 1 shown in FIG. 11 as an example, but the concept is the same for the combination No. 2.

[0054] As shown by the dotted line in FIG. 10(A), the s-wave laser light emitted from the light-emitting part LS1 is incident on the reflective polarizing plate R11 having reflection characteristics for the s-wave and is reflected, passes through the quarter-wave plate T1 arranged between the MEMS mirror 22 and the reflective polarizing plate R11 and is converted into circularly polarized light and is incident on the MEMS mirror 22. After being reflected by the MEMS mirror 22, it passes through the quarter-wave plate T4 and is converted into linearly polarized p-wave light, passes through the reflective polarizing plate R14 having transmission characteristics for the p-wave, and is irradiated outside the scanning light source unit 2. The quarter-wave plates T1 and T4 are arranged so that the light emitted from the light-emitting part LS1 is incident substantially vertically. In FIG. 10(A), the quarter-wave plate T2 and the quarter-wave plate T3 are omitted for ease of explanation, and the quarter-wave plates T2 and T3 are arranged at positions that do not overlap on the optical path of the light emitted from the light-emitting part LS1.

[0055] Also, as shown by the dotted line in FIG. 10(D), the s-wave laser light emitted from the light emitting unit LS4 is incident on the reflective polarizing plate R14 having reflection characteristics with respect to the s-wave, reflected, passes through the quarter-wave plate T4 disposed between the MEMS mirror 22 and the reflective polarizing plate R14, is converted into circularly polarized light, and is incident on the MEMS mirror 22. After being reflected by the MEMS mirror 22, it passes through the quarter-wave plate T1 and is converted into linearly polarized p-wave light, passes through the reflective polarizing plate R11 having transmission characteristics with respect to the p-wave, and is irradiated outside the scanning light source unit 2. The quarter-wave plates T1 and T4 are arranged such that the light emitted from the light emitting unit LS4 is incident substantially perpendicularly. In FIG. 10(D), the quarter-wave plates T2 and T3 are omitted for ease of explanation, and the quarter-wave plates T2 and T3 are arranged at positions that do not overlap the optical path of the light emitted from the light emitting unit LS4.

[0056] The relationship between the light emitting unit LS2 and the reflective polarizing plate R12 is the same. As shown by the dotted line in FIG. 10(B), the s-wave laser light emitted from the light emitting unit LS2 is incident on the reflective polarizing plate R12 having reflection characteristics with respect to the s-wave, reflected, passes through the quarter-wave plate T2 disposed between the MEMS mirror 22 and the reflective polarizing plate R12, is converted into circularly polarized light, and is incident on the MEMS mirror 22. After being reflected by the MEMS mirror 22, it passes through the quarter-wave plate T3 and is converted into linearly polarized p-wave light, passes through the reflective polarizing plate R13 having transmission characteristics with respect to the p-wave, and is irradiated outside the scanning light source unit 2. The quarter-wave plates T2 and T3 are arranged such that the light emitted from the light emitting unit LS2 is incident substantially perpendicularly. The quarter-wave plates T1 and T4 are arranged at positions that do not overlap the optical path of the light emitted from the light emitting unit LS2.

[0057] The relationship between the light emitting section LS3 and the reflective polarizing plate R13 is the same. As shown by the dotted line in Fig. 10(C), the s-wave laser light emitted from the light emitting section LS3 is incident on the reflective polarizing plate R13 having reflection characteristics with respect to the s-wave and is reflected. It passes through the quarter-wave plate T3 disposed between the MEMS mirror 22 and the reflective polarizing plate R13 and is converted into circularly polarized light and incident on the MEMS mirror 22. After being reflected by the MEMS mirror 22, it passes through the quarter-wave plate T2 and is converted into linearly polarized light of the p-wave, passes through the reflective polarizing plate R13 having transmission characteristics with respect to the p-wave, and is irradiated outside the scanning light source section 2. The quarter-wave plates T2 and T3 are arranged such that the light emitted from the light emitting section LS3 is incident substantially perpendicularly. Note that the quarter-wave plates T1 and T4 are arranged at positions that do not overlap on the optical path of the light emitted from the light emitting section LS3.

[0058] In addition, in each of the first and second modified embodiments, although a flat reflective polarizing plate has been described, a cube-shaped beam splitter may be used. In this case, there is an advantage that the optical path length does not shift.

[0059] The present disclosure has the following features (Appendix 1) An optical scanning device used in a device that performs object detection by irradiating light and receiving the reflected light thereof, a deflector, a light source having at least a first light emitting section that emits first light and a second light emitting section that emits second light having optical characteristics different from those of the first light, a first optical element that is arranged such that the first light emitted from the first light emitting section is incident thereon, and reflects the first light and makes it incident on the deflector, a second optical element that is arranged such that the second light emitted from the second light emitting section is incident thereon, and reflects the second light and makes it incident on the deflector, comprising the first optical element has optical characteristics of reflecting the first light and transmitting the second light, the second optical element has optical characteristics of reflecting the second light and transmitting the first light, an optical scanning device. (Supplementary Note 2) The first light and the second light have different wavelengths as the optical characteristics, The first optical element is a first dichroic mirror that reflects the first light and transmits the second light, The second optical element is a second dichroic mirror that reflects the second light and transmits the first light, The optical scanning device according to Supplementary Note 1. (Supplementary Note 3) The first light and the second light have different wavelengths as the optical characteristics, The first optical element is a first band-pass filter that reflects the first light and transmits the second light, The second optical element is a second band-pass filter that reflects the second light and transmits the first light, The optical scanning device according to Supplementary Note 1. (Supplementary Note 4) The difference in wavelength between the first light and the second light is 50 nm or more, The optical scanning device according to Supplementary Note 2 or 3. (Supplementary Note 5) The first light and the second light have different polarization directions as the optical characteristics, The first optical element is a first reflective polarizing plate that reflects the first light and transmits the second light, The second optical element is a second reflective polarizing plate that reflects the second light and transmits the first light, The optical scanning device according to Supplementary Note 1. (Supplementary Note 6) The difference in polarization direction between the first light and the second light is approximately 90°, The optical scanning device according to Supplementary Note 5. (Supplementary Note 7) The first light-emitting unit emits linearly polarized light as the first light, The second light-emitting unit emits linearly polarized light as the second light, The optical scanning device according to Supplementary Note 5 or 6. (Supplementary Note 8) An optical scanning device used in a device that performs object detection by irradiating light and receiving the reflected light thereof, A deflector, A light source having at least a first light emitting part and a second light emitting part that emit a first linearly polarized light, A first reflective polarizing plate that is arranged such that the first linearly polarized light emitted from the first light emitting part is incident thereon, reflects the first light from the first light emitting part, and transmits a second linearly polarized light whose polarization direction is approximately 90° different from that of the first light, A second reflective polarizing plate that is arranged such that the first linearly polarized light emitted from the second light emitting part is incident thereon, reflects the first linearly polarized light from the second light emitting part, and transmits a second linearly polarized light whose polarization direction is approximately 90° different from that of the first light, A first quarter-wave plate disposed between the first reflective polarizing plate and the deflector, A second quarter-wave plate disposed between the second reflective polarizing plate and the deflector, Including, The first linearly polarized light reflected by the first reflective polarizing plate passes through the first quarter-wave plate, is converted into circularly polarized light, enters and is reflected by the deflector, and then enters and passes through the second quarter-wave plate to be converted into the second linearly polarized light, enters and passes through the second reflective polarizing plate, The first linearly polarized light reflected by the second reflective polarizing plate passes through the second quarter-wave plate, is converted into circularly polarized light, enters and is reflected by the deflector, and then enters and passes through the first quarter-wave plate to be converted into the second linearly polarized light, enters and passes through the first reflective polarizing plate An optical scanning device. (Appendix 9) The optical scanning device according to any one of Appendices 1 to 8, A light receiving part that detects reflected light from the irradiation light emitted from the optical scanning device and generates a light receiving signal according to the intensity of the reflected light, A control part that controls the operation of the optical scanning device and generates point group information based on the light receiving signal, An object detection device including.

Explanation of reference numerals

[0060] 1: Controller, 2: Scanning light source unit (optical scanning device), 3: Light receiving unit, 10: Measurement control unit, 11: Deflection control unit, 12: Lighting control unit, 13: Distance measurement unit, 14: Communication unit, 20: MEMS driver, 21: Light source driver, 22: MEMS mirror, 30: Lens, 31: Optical filter, 32: Photodetector (light receiving element), 33: Light receiving circuit, LS: Light source, LS1, LS2, LS3, LS4: Light emitting unit, R: Optical element (dichroic mirror / reflective polarizing plate), R1, R2, R3, R4: Dichroic mirror, R11, R12, R13, R14: Reflective polarizing plate, T, T1, T2, T3, T4: Quarter-wave plate

Claims

1. An optical scanning device used in a device that performs object detection by irradiating light and receiving the reflected light, a deflector, a light source having at least a first light emitting part that emits first light and a second light emitting part that emits second light having optical characteristics different from those of the first light, a first optical element that is arranged so that the first light emitted from the first light emitting part is incident thereon, and reflects the first light and makes it incident on the deflector, a second optical element that is arranged so that the second light emitted from the second light emitting part is incident thereon, and reflects the second light and makes it incident on the deflector, comprising, the first optical element has an optical characteristic of reflecting the first light and transmitting the second light, the second optical element has an optical characteristic of reflecting the second light and transmitting the first light, an optical scanning device.

2. The first light and the second light have different wavelengths as the optical characteristics, the first optical element is a first dichroic mirror that reflects the first light and transmits the second light, the second optical element is a second dichroic mirror that reflects the second light and transmits the first light, The optical scanning device according to claim 1.

3. The first light and the second light have different wavelengths as the optical characteristics, the first optical element is a first band-pass filter that reflects the first light and transmits the second light, the second optical element is a second band-pass filter that reflects the second light and transmits the first light, The optical scanning device according to claim 1.

4. The difference in wavelength between the first light and the second light is 50 nm or more, The optical scanning device according to claim 2 or 3.

5. The first light and the second light have different polarization directions as the optical characteristics, the first optical element is a first reflective polarizing plate that reflects the first light and transmits the second light, the second optical element is a second reflective polarizing plate that reflects the second light and transmits the first light, The optical scanning device according to claim 1.

6. The difference in polarization direction between the first light and the second light is approximately 90°, The optical scanning device according to claim 5.

7. The first light emitting part emits linearly polarized light as the first light, The second light emitting part emits linearly polarized light as the second light, The optical scanning device according to claim 5.

8. An optical scanning device used in a device that performs object detection by irradiating light and receiving the reflected light, a deflector, A light source having at least a first light emitting portion and a second light emitting portion that emit a first linearly polarized light, A first reflective polarizing plate that is arranged so that the first linearly polarized light emitted from the first light emitting portion is incident thereon, reflects the first light from the first light emitting portion, and transmits a second linearly polarized light whose polarization direction is approximately 90° different from that of the first light, A second reflective polarizing plate that is arranged so that the first linearly polarized light emitted from the second light emitting portion is incident thereon, reflects the first linearly polarized light from the second light emitting portion, and transmits a second linearly polarized light whose polarization direction is approximately 90° different from that of the first light, A first quarter-wave plate disposed between the first reflective polarizing plate and the deflector, A second quarter-wave plate disposed between the second reflective polarizing plate and the deflector, Including, The first linearly polarized light reflected by the first reflective polarizing plate passes through the first quarter-wave plate, is converted into circularly polarized light, is incident on and reflected by the deflector, and then is incident on and passes through the second quarter-wave plate to be converted into the second linearly polarized light, and is incident on and passes through the second reflective polarizing plate, The first linearly polarized light reflected by the second reflective polarizing plate passes through the second quarter-wave plate, is converted into circularly polarized light, is incident on and reflected by the deflector, and then is incident on and passes through the first quarter-wave plate to be converted into the second linearly polarized light, and is incident on and passes through the first reflective polarizing plate An optical scanning device.

9. The optical scanning device according to claim 1 or claim 8, A light receiving portion that detects reflected light from the irradiation light emitted from the optical scanning device and generates a light receiving signal according to the intensity of the reflected light, A control portion that controls the operation of the optical scanning device and generates point group information based on the light receiving signal, An object detection device including the above.

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