Light detection device

Abstract

A light detection device (10) scans a detection region (DA) of an outside world with a projection light beam (PB) and detects a reflection light beam (RB) from the detection region (DA) with respect to the projection light beam (PB), and includes a light-receiving optical system (42) that guides the reflection light beam (RB) along a light-receiving optical axis (ROA), and a light receiver (45) that outputs a detection signal by receiving the reflection light beam (RB) imaged by the light-receiving optical system (42). The light receiver (45) is formed with a light-receiving surface (47) for which a light-receiving aspect ratio (RR) is set as an aspect ratio of a long side along a first reference axis (Y) orthogonal to the light-receiving optical axis (ROA). The light-receiving surface (47) is configured to be tilted about the first reference axis (Y) with respect to a posture along a second reference axis (X) orthogonal to the light-receiving optical axis (ROA) and the first reference axis (Y).

Description

[0001] Cross-referencing of related applications

[0002] This application is based on Japanese Patent Application No. 2021-039564, filed on March 11, 2021, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates to a light detection device. Background Technology

[0004] Optical detection devices that scan an external detection area with a projected light beam and detect the reflected light beam from the detection area are widely known. For example, in the optical detection device disclosed in Patent Document 1, the reflected light beam is guided by a lens and received by a light receiver, thereby outputting a detection signal.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2017-125765 Summary of the Invention

[0008] The optical detection device disclosed in Patent Document 1 designs the aspect ratio of the light-receiving surface in the light receiver to suppress false detections caused by stray light in order to suppress the scanning direction of the light beam projected by the scanning mirror. However, in the light-receiving surface, which is arranged perpendicular to the light-receiving optical axis of the lens that guides the reflected beam, if retroreflection of the reflected beam occurs, the retroreflection component of the reflected beam will be guided to the detection area along the light-receiving optical axis. As a result, depending on the reflectivity of the reflective target present in the detection area, ghosting may occur because the retroreflection component of the reflected beam is further reflected and returns to the light-receiving surface, thus causing false detections.

[0009] The subject of this disclosure is to provide an optical detection device that ensures detection accuracy.

[0010] The following describes the technical means of this disclosure used to solve the problem.

[0011] The first aspect of this disclosure is a light detection device that scans an external detection area with an emitted light beam and detects reflected light beams from the detection area relative to the emitted light beam, wherein the device comprises:

[0012] The light-receiving optical system guides the reflected light beam along the light-receiving optical axis; and

[0013] The light receiver receives the reflected light beam imaged by the light-receiving optical system and outputs a detection signal;

[0014] The light receiver has a light-receiving surface. For this light-receiving surface, the aspect ratio of the light-receiving surface is set along a first reference axis orthogonal to the light-receiving optical axis, which is the length-to-width ratio of the longer side.

[0015] The light-receiving surface is configured to be tilted about the first reference axis relative to the orientation along the second reference axis (X) which is orthogonal to the light-receiving optical axis and the first reference axis.

[0016] Thus, in the first approach, the light-receiving surface of the light receiver is set with a light-receiving aspect ratio along a first reference axis orthogonal to the light-receiving optical axis on its long side. Therefore, according to the first approach, on the light-receiving surface in a configuration orientation tilted about the first reference axis relative to the orientation along a second reference axis orthogonal to both the light-receiving optical axis and the first reference axis, even if retroreflection of the reflected beam occurs, the retroreflection component of the reflected beam can be guided as far as possible in a direction deviating from the light-receiving optical axis. Furthermore, according to the first approach, the light-receiving surface is tilted about the first reference axis along the long side of the light-receiving aspect ratio, thereby suppressing the imaging blur caused by the tilt in the direction of the short side of the aspect ratio intersecting the second reference axis.

[0017] As described above, according to the first method, it is possible to suppress the generation of ghosting caused by further reflection of the regressive reflection component, and also to suppress the degradation of detection resolution caused by the structure used to suppress the ghosting, thereby ensuring detection accuracy.

[0018] The second aspect of this disclosure is a light detection device that scans an external detection area with an emitted light beam and detects reflected light beams from the detection area relative to the emitted light beam, wherein the device comprises:

[0019] The light-receiving optical system guides the reflected light beam along the light-receiving optical axis;

[0020] The photodetector receives the reflected light beam imaged by the photodetector optical system and outputs a detection signal; and

[0021] A light-receiving prism refracts the reflected light beam at the front stage of the light receiver;

[0022] The light receiver has a light-receiving surface. For this light-receiving surface, the aspect ratio of the light-receiving surface is set along a first reference axis orthogonal to the light-receiving optical axis, which is the length-to-width ratio of the longer side.

[0023] The light-receiving prism has an optical surface formed by at least one of the incident surface and the exit surface, which is configured to be tilted about the first reference axis relative to an attitude along a second reference axis orthogonal to the light-receiving optical axis and the first reference axis.

[0024] Thus, in the second approach, the light-receiving surface of the light receiver is set with a light-receiving aspect ratio along a first reference axis orthogonal to the light-receiving optical axis on its long side. Therefore, according to the second approach, at least one of the incident and exit surfaces of the light-receiving prism that refracts the reflected beam on the front-stage side of the light receiver is formed as an optical surface tilted about the first reference axis relative to a second reference axis orthogonal to both the light-receiving optical axis and the first reference axis. This allows the light to be guided as far away from the light-receiving optical axis as possible, even if retroreflection of the reflected beam occurs on the light-receiving surface. Furthermore, according to the second approach, the optical surface of the light-receiving prism is tilted about the first reference axis along the long side of the light-receiving aspect ratio on the light-receiving surface, thereby suppressing imaging blur caused by this tilt in the short side direction of the aspect ratio.

[0025] As described above, according to the second method, it is possible to suppress the generation of ghosting caused by further reflection of the regressive reflection component, and also to suppress the degradation of detection resolution caused by the structure used to suppress the ghosting, thereby ensuring detection accuracy. Attached Figure Description

[0026] Figure 1 This is a schematic diagram showing the overall structure of the optical detection device according to the first embodiment.

[0027] Figure 2 This is a schematic diagram showing the projector of the first embodiment.

[0028] Figure 3 This is a schematic diagram showing the scanning unit and the light-receiving unit of the first embodiment.

[0029] Figure 4 This is a schematic diagram showing the scanning unit and the light-receiving unit of the first embodiment.

[0030] Figure 5 This is a schematic diagram showing the light-receiving unit of the first embodiment in an enlarged view.

[0031] Figure 6 This is a schematic diagram showing the light receiver of the first embodiment.

[0032] Figure 7 This is a schematic diagram showing the light-receiving unit of the first embodiment in an enlarged view.

[0033] Figure 8 This is a schematic diagram showing the overall structure of the optical detection device according to the second embodiment.

[0034] Figure 9 This is a schematic diagram showing the scanning unit and the light-receiving unit of the second embodiment.

[0035] Figure 10This is a schematic diagram showing the light-receiving unit of the second embodiment in an enlarged view.

[0036] Figure 11 This is a schematic diagram showing the light receiver of the second embodiment.

[0037] Figure 12 This is a schematic diagram showing the light-receiving unit of the second embodiment in an enlarged view.

[0038] Figure 13 This is a schematic diagram showing the overall structure of the optical detection device according to the third embodiment.

[0039] Figure 14 This is a schematic diagram showing the scanning unit and the light-receiving unit of the third embodiment.

[0040] Figure 15 This is a schematic diagram showing the light-receiving unit of the third embodiment in an enlarged view.

[0041] Figure 16 This is a schematic diagram showing the light-receiving unit of the third embodiment in an enlarged view.

[0042] Figure 17 This is a schematic diagram showing the light-receiving unit of the third embodiment in an enlarged view.

[0043] Figure 18 This is a schematic diagram showing the light-receiving unit of the third embodiment in an enlarged view.

[0044] Figure 19 This is a schematic diagram showing the light-receiving unit of the third embodiment in an enlarged view.

[0045] Figure 20 This is a schematic diagram showing the overall structure of the optical detection device according to the fourth embodiment.

[0046] Figure 21 This is a schematic diagram showing the scanning unit and the light-receiving unit of the fourth embodiment.

[0047] Figure 22 This is a schematic diagram showing the light-receiving unit of the fourth embodiment in an enlarged view.

[0048] Figure 23 This is a schematic diagram showing the light-receiving unit of the fourth embodiment in an enlarged view.

[0049] Figure 24 This is a schematic diagram showing the scanning unit and the light-receiving unit of a modified example.

[0050] Figure 25 This is a schematic diagram showing the scanning unit and the light-receiving unit of a modified example. Detailed Implementation

[0051] Hereinafter, several embodiments will be described based on the accompanying drawings. Furthermore, in each embodiment, repeated descriptions are sometimes omitted by using the same reference numerals for corresponding structural elements. Additionally, where only a portion of the structure is described in each embodiment, structures from other previously described embodiments can be applied to the remaining parts of that structure. Moreover, not only combinations of structures explicitly shown in the descriptions of each embodiment are possible, but structures from multiple embodiments can be partially combined with each other even without explicit description, provided that such combinations do not present particular obstacles.

[0052] <First Implementation Method>

[0053] like Figure 1 As shown, the light detection device 10 of the first embodiment of this disclosure is a LiDAR (Light Detection and Ranging / Laser Imaging Detection and Ranging) mounted on a vehicle that is a moving body. Furthermore, in the following description, unless otherwise specified, the directions front, back, up, down, left, and right are defined with reference to the vehicle on a horizontal plane. Additionally, the horizontal direction refers to a direction parallel to the horizontal plane, and the vertical direction refers to a direction perpendicular to the horizontal plane.

[0054] The light detection device 10 is disposed, for example, at at least one part of a vehicle, such as the front, left and right sides, rear, and top of the vehicle. The light detection device 10 scans a projection beam PB toward a detection area DA in the outside of the vehicle corresponding to the disposed part. The light detection device 10 detects the reflected light PB that is reflected back by a reflector in the detection area DA and uses it as the reflected beam RB. Thus, the projection beam PB that becomes the reflected beam RB is usually selected from light in the near-infrared region that is difficult for an outsider to see.

[0055] The light detection device 10 observes the reflective marker in the detection area DA by detecting the reflected beam RB. Here, the observation of the reflective marker refers to at least one of the following: the distance from the light detection device 10 to the reflective marker, the direction in which the reflective marker exists, and the reflection intensity of the reflected beam RB from the reflective marker. In the light detection device 10 applied to vehicles, the reflective marker that serves as a representative observation object can be at least one of moving objects such as pedestrians, cyclists, animals other than humans, and other vehicles. In the light detection device 10 applied to vehicles, the reflective marker that serves as a representative observation object can also be at least one of stationary objects such as guardrails, road signs, roadside structures, and debris on the road.

[0056] In the light detection device 10, a three-dimensional orthogonal coordinate system is defined by the X-axis, Y-axis, and Z-axis, which are three mutually orthogonal axes. Specifically, in the light detection device 10, the Y-axis, serving as the first reference axis, is set along the vertical direction of the vehicle. Furthermore, in the light detection device 10, the X-axis, serving as the second reference axis, is set along the horizontal direction of the vehicle. Figure 1 The portion to the left of the single-dotted line along the Y-axis (the cover plate 15 side described later) actually illustrates a cross section perpendicular to the portion to the right of the single-dotted line (the unit 21, 41 side described later).

[0057] The light detection device 10 is configured to include a housing 11, a light-emitting unit 21, a scanning unit 31, a light-receiving unit 41, and a controller 51. The housing 11 forms the outer shell of the light detection device 10. The housing 11 includes a light-shielding shell 12 and a cover plate 15.

[0058] The light-shielding shell 12 is formed of a light-shielding material such as synthetic resin or metal. The light-shielding shell 12 is generally box-shaped. It is constructed from individual components or a combination of multiple components. The light-shielding shell 12 internally defines a housing chamber 13 that houses the light-projecting unit 21, the scanning unit 31, the light-receiving unit 41, and the controller 51. The housing chamber 13 is shared by both the light-projecting unit 21 and the light-receiving unit 41 within the light-shielding shell 12. The light-shielding shell 12 has an open optical window 14. The optical window 14 is also shared by both the light-projecting unit 21 and the light-receiving unit 41.

[0059] The cover plate 15 is formed primarily of a substrate such as synthetic resin or glass that is transparent in the near-infrared region. For example, the cover plate 15 can be made transparent in the near-infrared region and shielded in the visible light region by coloring the substrate, forming an optical thin film, or attaching a film to the substrate surface. The cover plate 15 is generally flat or has a curved shape. The cover plate 15 completely seals the optical window 14 in a manner that allows both the projected beam PB and the reflected beam RB to pass through. Thus, the projected beam PB and the reflected beam RB can reciprocate between the receiving chamber 13 and the detection area DA, and the intrusion of foreign objects into the housing 11 can be prevented.

[0060] The projection unit 21 includes a projector 22 and a projection optics system 26. The projector 22 emits laser light in the near-infrared region, which becomes the projection beam PB. The projector 22 is disposed inside the housing 11 and held by a light-shielding shell 12.

[0061] like Figure 2As shown, the projector 22 is formed by arranging a plurality of laser oscillating elements 24 in an array on a substrate. Each laser oscillating element 24 is arranged in a single column along the Y-axis in the vertical direction of the vehicle. Each laser oscillating element 24 emits coherent laser light with consistent phase through a resonator structure that resonates the laser oscillating in the PN junction layer and a mirror layer structure that sandwiches the PN junction layer and repeatedly reflects the laser light. Each laser oscillating element 24 generates laser light in a pulsed manner, which becomes part of the projected beam PB, according to a control signal from the controller 51.

[0062] The projector 22 has a projection window 25, approximately rectangular in shape, formed on one side of the substrate. The projection window 25 is configured as an assembly of laser oscillation openings in each laser oscillation element 24. The aspect ratio RP of the projection window 25 is defined such that the longer side is along the Y-axis and the shorter side is along the X-axis. That is, the projection aspect ratio RP is set along the Y-axis, which serves as the first reference axis, and the X-axis, which serves as the second reference axis.

[0063] The laser beam projected from the laser oscillation opening of each laser oscillation element 24 serves as... Figure 1 In the detection area DA shown, a linear projection beam PB is simulated along the Y-axis and projected from the projection window 25. The projection beam PB may also include non-emitting portions in a predetermined direction along the Y-axis (hereinafter referred to as the Y-axis direction) corresponding to the arrangement spacing of the laser oscillation elements 24. Even in this case, a linear projection beam PB in which the non-emitting portions are macroscopically eliminated through diffraction can still be formed in the detection area DA.

[0064] The projection optical system 26 projects the projection beam PB from the projector 22 toward the scanning mirror 32 of the scanning unit 31. The projection optical system 26 is positioned between the projector 22 and the scanning mirror 32 in the optical path of the projection beam PB.

[0065] The projection optical system 26 performs at least one optical function, such as focusing, collimation, and shaping. The projection optical system 26 forms a projection optical axis POA along the Z-axis. The projection optical system 26 has at least one projection lens 27 held by a light-shielding shell 12. The at least one projection lens 27 is formed with a light-transmitting substrate, such as synthetic resin or glass, in a lens shape corresponding to the optical function it performs. The projection optical axis POA is, for example, defined as a virtual ray axis passing through the center of curvature of the lens surface in the at least one projection lens 27. The principal ray of the projection beam PB emitted from the center of the projection window 25 is guided along the projection optical axis POA.

[0066] The scanning unit 31 includes a scanning mirror 32 and a scanning motor 35. The scanning mirror 32 scans the projection beam PB projected from the projection optical system 26 of the projection unit 21 toward the detection area DA, and reflects the reflected beam RB from the detection area DA toward the projection beam PB toward the light-receiving optical system 42 of the light-receiving unit 41. The scanning mirror 32 is disposed between the cover plate 15 and the projection optical system 26 in the optical path of the projection beam PB, and between the cover plate 15 and the light-receiving optical system 42 in the optical path of the reflected beam RB.

[0067] The scanning mirror 32 is formed primarily of a substrate such as synthetic resin or glass. The scanning mirror 32 is generally flat. Regarding the scanning mirror 32, for example, a reflective surface 33 with a rectangular outline is formed into a mirror shape by depositing a reflective film such as aluminum, silver, or gold on one side of the substrate.

[0068] like Figure 1 , Figure 3 As shown, the scanning mirror 32 has a rotation axis 34 that is rotatably held by the light-shielding shell 12. The vertical direction of the vehicle, extending from the rotation center line CM along the rotation axis 34, is the Y-axis direction, which substantially coincides with the long side direction of the reflecting surface 33. By rotating about the rotation center line CM along the Y-axis, the scanning mirror 32 can adjust the normal direction of the reflecting surface 33 about this rotation center line CM. In particular, the scanning mirror 32 oscillates within a limited drive range DR, for example, via a mechanical or electrical stop. Thus, the projected light beam PB reflected by the scanning mirror 32 is limited to not deviating from the optical window 14.

[0069] like Figure 1 As shown, the scanning mirror 32 is provided for both the light-emitting unit 21 and the light-receiving unit 41. That is, the scanning mirror 32 is provided for both the light-emitting beam PB and the reflected beam RB. Therefore, the scanning mirror 32 has a light-emitting reflective portion 331 used in emitting the light-emitting beam PB and a light-receiving reflective portion 332 used in receiving the reflected beam RB, which are offset in the Y-axis direction on the reflecting surface 33. The light-emitting reflective portion 331 and the light-receiving reflective portion 332 are provided in mutually separated positions or in positions where each at least partially overlaps with the other.

[0070] The projected light beam PB is reflected by the projection reflector 331, whose normal direction is adjusted according to the rotation drive of the scanning mirror 32, thereby scanning the detection area DA in time and space through the optical window 14. The scanning of the detection area DA by the projected light beam PB is substantially limited to a horizontal scan due to the rotation drive of the scanning mirror 32 around the rotation center line CM. Thus, the driving range DR of the scanning mirror 32 defines the horizontal viewing angle in the detection area DA.

[0071] The projected light beam PB is reflected by the reflector present in the detection area DA, thus becoming the reflected light beam RB returning to the light detection device 10. The reflected light beam RB again passes through the optical window 14 and enters the light-receiving reflection section 332 of the scanning mirror 32. Here, the speeds of the projected light beam PB and the reflected light beam RB are sufficiently large relative to the rotational speed of the scanning mirror 32. As a result, the reflected light beam RB is reflected from the light-receiving reflection section 332 in the scanning mirror 32, which has a rotational angle approximately the same as that of the projected light beam PB, and is thus guided to the light-receiving optical system 42 of the light-receiving unit 41 in a manner opposite to that of the projected light beam PB.

[0072] A scanning motor 35 is disposed inside the housing 11 around the scanning mirror 32. The scanning motor 35 is, for example, a voice coil motor, a brushed DC motor, or a stepper motor. The output shaft of the scanning motor 35 is directly coupled to the rotation shaft 34 of the scanning mirror 32, or indirectly, for example, via a drive mechanism such as a speed reducer. The scanning motor 35 is held by the light-shielding housing 12 so as to drive the rotation shaft 34 to rotate together with the output shaft. The scanning motor 35 drives the rotation shaft 34 to rotate within the drive range DR according to the control signal from the controller 51.

[0073] like Figure 1 , Figure 3 As shown, the light-receiving unit 41 includes a light-receiving optical system 42 and a light receiver 45. The light-receiving optical system 42 guides the reflected light beam RB from the scanning mirror 32 toward the light receiver 45. The light-receiving optical system 42 is positioned below the projection optical system 26 in the vertical direction of the vehicle along the Y-axis.

[0074] The light-receiving optical system 42 performs an optical function by imaging the reflected beam RB onto the light receiver 45. The light-receiving optical system 42 forms a light-receiving optical axis ROA along the Z-axis. The light-receiving optical system 42 has at least one light-receiving lens 43 held by the light-shielding shell 12 via the lens barrel 44. The at least one light-receiving lens 43 is formed with a light-transmitting substrate such as synthetic resin or glass as its main body and is shaped to correspond to the optical function it performs (e.g., ...). Figure 3 Shape or as described later Figure 5 (shape, etc.). The light-receiving optical axis ROA is defined, for example, as a virtual ray axis passing through the center of curvature of the lens surface, etc., in at least one light-receiving lens 43.

[0075] The principal ray of the reflected beam RB reflected from the light-receiving and reflecting part 332 of the scanning mirror 32 is as follows: Figure 3 , Figure 4 As shown, the light is guided along the optical axis ROA at any rotation angle within the drive range DR. That is, the optical axis ROA along which the reflected beam RB is located becomes the optical axis along which the reflected beam RB is located within the entire drive range DR of the rotating scanning mirror 32.

[0076] like Figure 1 , Figure 3 , Figure 4 As shown, the light-receiving optical system 42 has a lens barrel 44 held by a light-shielding shell 12. The lens barrel 44 is mainly formed of a light-shielding substrate such as synthetic resin or metal. The lens barrel 44 is generally cylindrical. The lens barrel 44 houses and positions at least one light-receiving lens 43.

[0077] The light receiver 45 receives the reflected light beam RB imaged by the light-receiving optical system 42 and outputs a detection signal. The light receiver 45 is disposed inside the housing 11 and held by the light-shielding shell 12. The light receiver 45 is positioned below the projector 22 and on the light-receiving optical axis ROA in the vertical direction of the vehicle along the Y-axis. Figures 3-5 As shown, in the light receiver 45, a tilt axis IA is defined, which is orthogonal to the Y-axis and tilted at an acute angle on one side of the Y-axis and an obtuse angle on the opposite side of the Y-axis relative to the light-receiving optical axis ROA (i.e., the Z-axis) and the X-axis.

[0078] As in Figure 6 As shown in thick lines, the light receiver 45 is formed by arranging a plurality of light-receiving pixels 46 in an array on a substrate. Each light-receiving pixel 46 is arranged in a single column along the Y-axis in the vertical direction of the vehicle. (As shown in...) Figure 6 As shown by thin lines, each light-receiving pixel 46 is composed of multiple light-receiving elements 461. For each light-receiving pixel 46, the light-receiving elements 461 are arranged in a predetermined number along both the Y-axis and the tilt axis IA. That is, each light-receiving pixel 46 has multiple light-receiving elements 461, therefore the output value varies depending on its response number. Therefore, by grouping multiple light-receiving elements 461 together for each light-receiving pixel 46 as the output, the dynamic range can be improved. The light-receiving elements 461 of each light-receiving pixel 46 are constructed, for example, using a photodiode such as a single-photon avalanche diode (SPAD). The light-receiving elements 461 of each light-receiving pixel 46 can also be integrally constructed by stacking a microlens array in front of a photodiode array. Furthermore, in Figure 6 In the text, a portion of the markings attached to the light-receiving element 461 has been omitted.

[0079] like Figure 1 , Figures 3-6As shown, the light receiver 45 has a rectangular light-receiving surface 47 formed on one side of the substrate. The light-receiving surface 47 is configured as an assembly of the incident surfaces of each light-receiving pixel 46. The geometric center of the rectangular outline of the light-receiving surface 47 is located on the light-receiving optical axis ROA, or is aligned in a set direction (hereinafter referred to as the X-axis direction) from the light-receiving optical axis ROA to the X-axis. Each light-receiving pixel 46 detects the reflected light beam RB incident on the incident surface constituting the light-receiving surface 47 by receiving it through its respective light-receiving element 461.

[0080] The aspect ratio RR of the light-receiving surface 47 is defined such that the longer side is along the Y-axis and the shorter side is along the inclined axis IA. That is, the light-receiving aspect ratio RR of the first embodiment differs from the projection aspect ratio RP, and is set along the Y-axis, which serves as the first reference axis, and the inclined axis IA, which serves as the X-axis, which serves as the second reference axis, and the light-receiving optical axis ROA. Here, corresponding to the projection beam PB, which is simulated as a line in the detection region DA, the reflected beam RB is a beam that extends in a linear shape.

[0081] like Figure 1 As shown, the photodetector 45 integrates a decoder 48. The decoder 48 sequentially reads out the electrical pulses generated by each photodetector pixel 46 corresponding to the detection of the reflected beam RB through sampling processing. The decoder 48 outputs the sequentially read electrical pulses as detection signals to the controller 51. When the sampling processing ends by reading out the electrical pulses, the detection of the reflector in the detection area DA also ends.

[0082] The controller 51 controls the observation of the reflective target in the detection area DA. The controller 51 is primarily composed of at least one computer, including a processor and memory. The controller 51 is connected to the projector 22, the scanning motor 35, and the receiver 45. The controller 51 outputs control signals to the projector 22 to generate a projected beam PB by oscillating each laser oscillation element 24 at the emission timing. The controller 51 outputs control signals to the scanning motor 35 to control the scanning and reflection of the scanning mirror 32, which is synchronized with the emission timing of the projected beam PB. Based on the emission timing of the projector 22 and the scanning and reflection of the scanning mirror 32, the controller 51 processes the electrical pulses output as detection signals from the receiver 45, thereby generating observation data of the reflective target in the detection area DA.

[0083] Next, the detailed structure of the light-receiving unit 41 will be explained.

[0084] like Figure 1 , Figures 3-5As shown, in the light-receiving optical system 42 of the light-receiving unit 41, the lens barrel 44 is formed with an aperture 442 for narrowing the exit 441 on the side of the light receiver 45. The aperture 442 gives the exit 441 a rectangular profile with an aspect ratio of the long side along the Y-axis and the short side along the X-axis. The aperture diameter φ of the aperture 442, which is the inner dimension of the exit 441, is set as small as possible within the limit of being able to emit all the reflected beam RB returning from the detection area DA.

[0085] Regarding the aperture diameter φ of aperture 442, as follows: Figure 5 As shown, on a section perpendicular to the Y-axis and located on the light-receiving optical axis ROA, it can be set according to the following Equation 1. In Equation 1, L is the separation distance on the light-receiving optical axis ROA from the incident end of the aperture 442 to the light-receiving surface 47 in the light receiver 45. In Equation 1, θ is the maximum angle relative to the light-receiving optical axis ROA of the light rays incident on the light-receiving surface 47 from the incident end of the last light-receiving lens 43 or the last light-receiving lens 43 among a group of light-receiving lenses 43 via the incident end of the exit 441 narrowed by the aperture 442. In Equation 1, F is the F-value set for the individual light-receiving lens 43 or the combined value of the F-values ​​set for the multiple light-receiving lenses 43.

[0086] φ=2·L·tan(θ)=2·L·tan(sin-1(1 / (2·F)))…Equation 1

[0087] like Figure 1 , Figures 3-5 As shown, in the light-receiving optical system 42, a light-absorbing surface 443 is formed on the lens barrel 44 around the exit 441 (i.e., around the aperture 442) on the side of the light receiver 45. The light-absorbing surface 443 is formed by a blackening treatment, such as anodizing, plating, or coating, on the outer surface of the substrate. In particular, the light-absorbing surface 443 can be provided on the entire opposing outer wall surface of the lens barrel 44 facing the light receiver 45 in the direction of the light-receiving optical axis ROA, which is the Z-axis (hereinafter referred to as the Z-axis direction). In the case of retroreflection at the light-receiving surface 47 incident on the light receiver 45 by the reflected beam RB, the retroreflection component RC of the reflected beam RB is transmitted through a process such as... Figures 3-5 In this way, the light incident on the light-absorbing surface 443 can be absorbed.

[0088] like Figure 1 , Figures 3-6As shown, the essentially planar light-receiving surface 47 in the light receiver 45 is configured to extend in a posture extending in the set direction of the tilt axis IA and the Y-axis direction. Therefore, the posture of the light-receiving surface 47 is tilted about the Y-axis, which is the first reference axis, relative to its posture along the X-axis (which serves as the second reference axis). The X-axis is the axis intersecting the short side direction of the light-receiving aspect ratio RR (which serves as the set direction of the tilt axis IA), and the Y-axis is the axis along the long side direction of RR. Figures 3-5 As shown, on a cross section perpendicular to the Y-axis and located on the light-receiving optical axis ROA, one side of the light-receiving surface 47, which is clamped on both sides of the light-receiving optical axis ROA along the X-axis direction, can also be tilted towards the direction close to the light-receiving optical axis ROA.

[0089] like Figure 5 , Figure 7 As shown, from the X-axis towards the light-receiving optical axis ROA (in Figure 5 , Figure 7 The tilt angle ψ of the light-receiving surface 47 (in the counterclockwise direction) is, for example, set to an acute angle in the range of the maximum angle θ in Equation 1. Here, corresponding to an increase in the tilt angle ψ, the retroreflection component RC of the reflected beam RB on the light-receiving surface 47 is more likely to deviate from the light-receiving optical axis ROA. On the other hand, corresponding to a decrease in the tilt angle ψ, the imaging blur of the reflected beam RB on the light-receiving surface 47 is particularly difficult to produce in the direction set by the tilt axis IA (i.e., the direction of the shorter side of the light-receiving aspect ratio RR). Therefore, the tilt angle ψ can be set according to a balance (i.e., a trade-off) between the ease with which the retroreflection component RC deviates and the ease with which imaging blur is produced.

[0090] <Effects>

[0091] The effects of the first embodiment described above will be explained below.

[0092] In the first embodiment, the light-receiving surface 47 of the light receiver 45 is given a light-receiving aspect ratio RR along the Y-axis, which is orthogonal to the light-receiving optical axis ROA and serves as a first reference axis. Therefore, according to the first embodiment, even if retroreflection of the reflected beam RB occurs on the light-receiving surface 47, which is in a configuration orientation tilted about the Y-axis relative to the orientation along the X-axis, which is orthogonal to both the light-receiving optical axis ROA and the Y-axis, it can still achieve the desired light quality. Figure 5 , Figure 7 In this way, the retroreflection component RC of the reflected beam RB is guided as far as possible away from the light-receiving optical axis ROA. Furthermore, according to the first embodiment, the light-receiving surface 47 is tilted around the Y-axis along the long side of the light-receiving aspect ratio RR, thereby suppressing the imaging blur caused by the tilt in the short side direction of the aspect ratio RR that intersects the X-axis.

[0093] As described above, according to the first embodiment, the generation of ghosting caused by further reflection of the retroreflection component RC can be suppressed, and the degradation of detection resolution caused by the structure used to suppress the ghosting can also be suppressed, thereby ensuring detection accuracy. Here, in particular, when ghosting occurs due to the retroreflection component RC, undesirable situations may occur, such as erroneously detecting a distance twice the actual distance to the reflector. In contrast, in the optical detection device 10, which can suppress false detections by suppressing the generation of ghosting, detection accuracy can be ensured.

[0094] According to the first embodiment, a plurality of light-receiving pixels 46 constituting the light-receiving surface 47 are arranged in a single column along the Y-axis along the long side of the light-receiving aspect ratio RR. Accordingly, the expansion of the light-receiving surface 47 can be minimized as much as possible in the short side direction of the light-receiving aspect ratio RR, which intersects the X-axis. Therefore, it has the effect of suppressing the degradation of detection resolution caused by imaging blur, thereby improving detection accuracy.

[0095] According to the first embodiment, the scanning mirror 32, which scans the detection area DA with the projection beam PB and reflects the reflected beam RB towards the light-receiving optical system 42, is rotated about the rotation center line CM along the Y-axis. Therefore, as long as the light-receiving optical system 42 guides the reflected beam RB along the light-receiving optical axis ROA within the entire driving range DR of the scanning mirror 32, it is possible to suppress the generation of ghosting and the degradation of detection resolution in the entire area of ​​the detection area DA scanned by the projection beam PB, thereby improving detection accuracy.

[0096] According to the first embodiment, the projector 22, which emits a projection beam PB toward the scanning mirror 32, forms a projection window 25 with a projection aspect ratio RP whose long side is set to be the same as the long side of the light-receiving aspect ratio RR along the Y-axis. Accordingly, imaging blurring on the light-receiving surface 47 can be suppressed in the Y-axis direction, which is the common long side direction of both the light-receiving aspect ratio RR and the projection aspect ratio RP. Therefore, it has the effect of suppressing detection resolution degradation, thereby improving detection accuracy.

[0097] According to the first embodiment, the light-receiving lens 43 of the light-receiving optical system 42 images the reflected beam RB onto the light receiver 45. Accordingly, the retroreflection component RC of the reflected beam RB generated on the light-receiving surface 47 can be limited from being reflected due to retroreflection onto the light-receiving lens 43. Therefore, the generation of light spots caused by the retroreflection component RC returning to the light-receiving lens 43 can also be suppressed, thereby improving detection accuracy.

[0098] According to the first embodiment, in the light-receiving optical system 42, the light-receiving lens 43 is housed in the lens barrel 44. Accordingly, the retroreflection component RC of the reflected light beam RB generated on the light-receiving surface 47 can be prevented from becoming stray light due to reflection within the light detection device 10 (specifically, within the housing 11) and heading towards the detection area DA. Therefore, the generation of ghosting caused by the stray light formation of the retroreflection component RC can also be suppressed, thereby improving detection accuracy.

[0099] According to the first embodiment, in the lens barrel 44, the exit 441 on the light receiver 45 side is narrowed by the aperture 442. Accordingly, the retroreflection component RC of the reflected light beam RB generated on the light-receiving surface 47 can be limited from being incident back onto the light-receiving lens 43 due to incident into the lens barrel 44, and from being reflected onto the inner wall surface due to incident into the lens barrel 44. Therefore, the generation of light spots and clutter caused by the incident of the retroreflection component RC into the lens barrel 44 can also be suppressed, thereby improving detection accuracy.

[0100] According to the first embodiment, in the lens barrel 44, around the emission outlet 441 on the light receiving surface 47, the retroreflection component RC of the reflected light beam RB generated thereon can be absorbed by the light absorption surface 443. This reduces the reflectivity of the retroreflection component RC incident on the outer wall surface of the lens barrel 44. Therefore, it also suppresses the generation of clutter caused by the reflection of the retroreflection component RC from the outer wall surface in the lens barrel 44, thereby improving detection accuracy.

[0101] <Second Implementation Method>

[0102] The second embodiment is a variation of the first embodiment.

[0103] like Figures 8-11 As shown, in the light-receiving unit 2041 of the second embodiment, the light-receiving surface 2047 of the light receiver 2045 is configured in an orientation substantially orthogonal to the light-receiving optical axis ROA along the Z-axis. Therefore, the light-receiving aspect ratio RR of the light-receiving surface 2047 is set along the Y-axis (serving as the first reference axis) and the X-axis (serving as the second reference axis), similar to the projection aspect ratio RP. That is, regarding the light-receiving surface 2047 of the second embodiment, which is composed of a plurality of light-receiving pixels 46 arranged in a single column, similar to the first embodiment, it extends along the long side direction of the light-receiving aspect ratio RR (which is the Y-axis direction) and the short side direction of the light-receiving aspect ratio RR (which is the X-axis direction).

[0104] like Figures 8-10As shown, the light-receiving unit 2041 in the second embodiment also includes a light-receiving prism 2049. The light-receiving prism 2049 is disposed inside the housing 11 between the emission outlet 441 of the light-receiving optical system 42 and the light-receiving surface 2047 of the light receiver 2045. The light-receiving prism 2049 is held directly by the light-shielding shell 12, or indirectly by the light-shielding shell 12 via the light receiver 2045.

[0105] The light-receiving prism 2049 refracts the reflected light beam RB at the front stage of the light receiver 2045. The light-receiving prism 2049 is formed primarily of a light-transmitting substrate such as synthetic resin or glass. The light-receiving prism 2049 has an incident surface 2492 and an exit surface 2493 that are at an acute angle to each other and are not parallel, serving as optical surfaces that impart a refractive effect to the reflected light beam RB.

[0106] In the setting direction of the light-receiving optical axis ROA, which is the Z-axis direction, the incident surface 2492 faces the exit outlet 441 of the light-receiving optical system 42. Regarding the incident surface 2492, it can be, for example, given a rectangular profile with an aspect ratio along the Y-axis, within the limit that allows all the reflected beam RB returning from the detection region DA to be incident and at least a portion of the retroreflection component RC incident from the light-receiving surface 2047 to the exit surface 2493 to be emitted. In the setting direction of the light-receiving optical axis ROA, the exit surface 2493 faces the light-receiving surface 2047 of the light receiver 2045. Regarding the exit surface 2493, it can be, for example, given a rectangular profile with an aspect ratio along the Y-axis, within the limit that allows all the reflected beam RB incident from the detection region DA to be emitted and at least a portion of the retroreflection component RC from the light-receiving surface 2047 to be incident.

[0107] In the light-receiving prism 2049, the essentially planar incident surface 2492 is configured to extend in the set direction of the tilt axis IA and the Y-axis direction. Thus, the orientation of the incident surface 2492 is tilted about the Y-axis, which is the first reference axis, relative to its orientation along the X-axis (which serves as the second reference axis). The X-axis, which serves as the second reference axis, is the axis intersecting the set direction of the tilt axis IA and is set along the short side direction of the light-receiving aspect ratio RR on the light-receiving surface 2047. The Y-axis, which serves as the first reference axis, is the axis along the long side direction of this aspect ratio RR. Figure 9 , Figure 10 As shown, on a cross section perpendicular to the Y-axis and located on the light-receiving optical axis ROA, one side of the incident surface 2492, which is sandwiched between the two sides of the light-receiving optical axis ROA along the X-axis direction, can also be tilted towards the direction of the light-receiving optical axis ROA.

[0108] like Figure 10 , Figure 12 As shown, from the X-axis towards the light-receiving optical axis ROA (in Figure 10 , Figure 12 The tilt angle ω of the incident surface 2492 (clockwise) is, for example, set to an acute angle within the range of the maximum angle θ defined by Equation 1 in the first embodiment. Here, corresponding to an increase in the tilt angle ω, the retroreflection component RC of the reflected beam RB on the light-receiving surface 2047 is more likely to deviate from the light-receiving optical axis ROA. On the other hand, corresponding to a decrease in the tilt angle ω, the imaging blur of the reflected beam RB on the light-receiving surface 2047 is particularly difficult to produce in the X-axis direction (i.e., the direction of the shorter side of the light-receiving aspect ratio RR). Therefore, the tilt angle ω can be set according to a balance (i.e., a trade-off) between the ease with which the retroreflection component RC deviates and the ease with which imaging blur is produced.

[0109] like Figures 8-10 As shown, in the light-receiving prism 2049, the substantially planar emission surface 2493 is configured in an orientation substantially orthogonal to the light-receiving optical axis ROA along the Z-axis. Thus, similar to the light-receiving surface 2047, the emission surface 2493 extends in the Y-axis and X-axis directions. Therefore, in particular, the emission surface 2493 can be disposed overlapping the light-receiving surface 2047. The emission surface 2493 can also be directly overlapped with the light-receiving surface 2047, or indirectly overlapped with the light-receiving surface 2047 through a protective glass covering the light-receiving surface 2047. Such an overlapping emission surface 2493 can also be directly bonded to the light-receiving surface 2047 by, for example, a light-transmitting optical adhesive, or indirectly bonded to the light-receiving surface 2047 via the optical adhesive and the protective glass of the light-receiving surface 2047, thereby integrating with the light receiver 2045. The light-receiving prism 2049 can also be held directly by the light-shielding shell 12, which is a different component from it, or can be held indirectly by the light-shielding shell 12 via other components, thereby maintaining the overlapping configuration of the emission surface 2493 with the light-receiving surface 2047. The light-receiving prism 2049 can also constitute the protective glass of the light-receiving surface 2047 itself.

[0110] <Effects>

[0111] The following describes the unique effects of the second embodiment described above.

[0112] In the second embodiment, the light-receiving surface 2047 of the light receiver 2045 is also given a light-receiving aspect ratio RR along the Y-axis, which is orthogonal to the light-receiving optical axis ROA. Therefore, according to the second embodiment, the incident surface 2492 of the light-receiving prism 2049, which refracts the reflected beam RB on the front-stage side of the light receiver 2045, is formed as an optical surface tilted about the Y-axis relative to the orientation along the X-axis, which is orthogonal to both the light-receiving optical axis ROA and the Y-axis. Thus, even if retroreflection of the reflected beam RB occurs on the light-receiving surface 2047, the retroreflection component of the reflected beam RB can be guided as far as possible away from the light-receiving optical axis ROA.

[0113] Furthermore, according to the second embodiment, the incident surface 2492 of the light-receiving prism 2049 is tilted around the Y-axis along the long side of the light-receiving aspect ratio RR on the light-receiving surface 2047, thereby suppressing the image blurring caused by the tilt in the short side direction of the aspect ratio RR. In particular, the light-receiving aspect ratio RR on the light-receiving surface 2047 is set along the Y-axis and X-axis respectively, thus facilitating the installation of the light receiver 2045 and suppressing image blurring in the short side direction of the aspect ratio RR along the X-axis.

[0114] As described above, according to the second embodiment, it is possible to suppress the generation of ghosting caused by further reflection of the regressive reflection component RC, and also to suppress the degradation of detection resolution caused by the structure used to suppress the ghosting, thereby ensuring detection accuracy.

[0115] Furthermore, in the second embodiment, the plurality of light-receiving pixels 46 constituting the light-receiving surface 2047 are also arranged in a single column along the Y-axis along the long side of the light-receiving aspect ratio RR. Accordingly, the expansion of the light-receiving surface 2047 can be minimized as much as possible in the short side direction of the light-receiving aspect ratio RR along the X-axis. Therefore, it has the effect of suppressing the degradation of detection resolution caused by imaging blur, thereby improving detection accuracy.

[0116] <Third Implementation Method>

[0117] The third embodiment is a variation formed by combining the first embodiment and the second embodiment.

[0118] like Figures 13-15 As shown, the light-receiving unit 3041 of the third embodiment includes a light receiver 45 with an inclined light-receiving surface 47 and a light-receiving prism 2049 with an inclined incident surface 2492. Figure 14 , Figure 15As shown, in a cross-section perpendicular to the Y-axis and located on the light-receiving optical axis ROA, on the two sides sandwiching the light-receiving optical axis ROA along the X-axis, the side of the light-receiving surface 47 inclined towards the light-receiving optical axis ROA along the tilt axis IA1 is different from the side of the incident surface 2492 inclined towards the light-receiving optical axis ROA along the tilt axis IA2. That is, the light-receiving surface 47 and the incident surface 2492 are inclined in the opposite direction to the first reference axis Y-axis relative to their orientation along the second reference axis, i.e., the X-axis.

[0119] like Figures 15-19 As shown, the tilt angle ψ of the light-receiving surface 47 in the direction from the X-axis close to the light-receiving optical axis ROA and the tilt angle ω of the incident surface 2492 in the direction from the X-axis close to the light-receiving optical axis ROA are set to be the same or different. In the third embodiment, the tilt angles ψ and ω may also be set, for example, to acute angles in the range of the maximum angle θ defined by Equation 1 in the first embodiment.

[0120] Assuming the tilt angles ψ and ω are set below the specified upper limit angles, and both tilt angles ψ and ω are set to the upper limit angles... Figure 15 In the middle, one of the tilt angles ψ and ω is changed to be less than the upper limit angle. Figure 16 , Figure 17 In comparison, the retroreflective component (RC) is more prone to deviating from the optical axis (ROA). Assuming the tilt angle ψ is set to a fixed value, the more the tilt angle ω follows... Figure 16 , Figure 15 , Figure 18 As the order of increasing, the more easily the retroreflective component RC deviates from the optical axis ROA. Assuming the tilt angle ω is set to a fixed value, the more the tilt angle ψ follows... Figure 17 , Figure 15 , Figure 19 As the order increases, the regression reflection component (RC) is more likely to deviate from the optical axis (ROA).

[0121] <Effects>

[0122] The following describes the unique effects of the third embodiment described above.

[0123] According to the third embodiment, the light-receiving surface 47 of the light receiver 45 and the incident surface 2492 of the light-receiving prism 2049 are respectively tilted around the Y-axis, which serves as the first reference axis, along the long side of the light-receiving aspect ratio RR on the light-receiving surface 47. Accordingly, imaging blurring can be suppressed in the direction of the short side of the light-receiving aspect ratio RR on the light-receiving surface 47, which intersects the X-axis, which serves as the second reference axis. Therefore, it has the effect of suppressing the degradation of detection resolution caused by imaging blurring, thereby improving detection accuracy.

[0124] <Fourth Implementation Method>

[0125] The fourth embodiment is a variation of the third embodiment.

[0126] like Figures 20-22 As shown, the light-receiving unit 4041 of the fourth embodiment includes a light-receiving prism 4049, which is equivalent to the light-receiving prism 2049 rotated about the Y-axis. In this light-receiving prism 4049, the substantially planar incident surface 4492 is configured in an orientation substantially orthogonal to the light-receiving optical axis ROA along the Z-axis. Thus, unlike the light-receiving surface 47 of the light receiver 45, the incident surface 4492 extends in both the Y-axis and X-axis directions.

[0127] like Figure 21 , Figure 22 As shown, in the light-receiving prism 4049, the substantially planar exiting surface 4493, which is not parallel to the incident surface 4492, is configured to extend in the set direction of the tilt axis IA and the Y-axis direction. Thus, the orientation of the exiting surface 4493 is tilted relative to its orientation along the X-axis, which serves as a second reference axis, about the Y-axis, which serves as a first reference axis. The X-axis, serving as the second reference axis, is the axis that intersects the short side direction of the light-receiving aspect ratio RR on the light-receiving surface 47, which serves as the set direction of the tilt axis IA. The Y-axis, serving as the first reference axis, is the axis along the long side direction of the aspect ratio RR.

[0128] like Figure 21 , Figure 22 As shown, in a cross-section perpendicular to the Y-axis and located on the light-receiving optical axis ROA, on both sides sandwiching the light-receiving optical axis ROA along the X-axis, the side where the light-receiving surface 47 is inclined towards the light-receiving optical axis ROA along the tilted axis IA, and the side where the emission surface 4493, which shares the tilted axis IA with the light-receiving surface 47, is inclined towards the light-receiving optical axis ROA, are the same. That is, the light-receiving surface 47 and the emission surface 4493 are inclined in the same direction around the first reference axis Y-axis relative to their orientation along the second reference axis, i.e., the X-axis.

[0129] The tilt angle ψ of the light-receiving surface 47 in the direction from the X-axis close to the light-receiving optical axis ROA and the tilt angle ω of the emission surface 4493 in the direction from the X-axis close to the light-receiving optical axis ROA are as follows: Figure 22 , Figure 23The sizes are set to be the same or different as shown. In the fourth embodiment, the tilt angles ψ and ω can also be set, for example, to acute angles in the range of the maximum angle θ defined by Equation 1 in the first embodiment. Here, in particular, the emitting surface 4493, whose tilt angle ω is set to the same angle as the tilt angle ψ of the light-receiving surface 47, can be disposed overlappingly on the light-receiving surface 47. The emitting surface 4493 can also be disposed directly overlappingly on the light-receiving surface 47, or indirectly overlappingly on the light-receiving surface 47 through a protective glass covering the light-receiving surface 47. The emitting surface 4493 disposed in such an overlapping manner can also be directly bonded to the light-receiving surface 47 by, for example, a light-transmitting optical adhesive, or indirectly bonded to the light-receiving surface 47 via the optical adhesive and the protective glass of the light-receiving surface 47, and thus integrated with the light receiver 45. The light-receiving prism 4049 can also be held directly by the light-shielding shell 12, which is a different component from it, or can be held indirectly by the light-shielding shell 12 via other components, thereby maintaining the overlapping configuration of the emission surface 4493 with the light-receiving surface 47. The light-receiving prism 4049 can also constitute the protective glass of the light-receiving surface 47 itself.

[0130] <Effects>

[0131] The following describes the unique effects of the fourth embodiment described above.

[0132] According to the fourth embodiment, the light-receiving surface 47 of the light receiver 45 and the emission surface 4493 of the light-receiving prism 4049 are respectively tilted around the Y-axis, which serves as the first reference axis, along the long side of the light-receiving aspect ratio RR on the light-receiving surface 47. Accordingly, imaging blurring can be suppressed in the direction of the short side of the light-receiving aspect ratio RR on the light-receiving surface 47, which intersects the X-axis, which serves as the second reference axis. Therefore, it has the effect of suppressing the degradation of detection resolution caused by imaging blurring, thereby improving detection accuracy.

[0133] <Other Implementation Methods>

[0134] The above describes several implementation methods, but this disclosure is not limited to these implementation methods and can be applied to various implementation methods and combinations without departing from the spirit of this disclosure.

[0135] In a modified example, the laser oscillation element 24 constituting the projection window 25 can also be arranged in multiple columns along the Y-axis in the X-axis direction. In a modified example, the plurality of light-receiving pixels 46 constituting the light-receiving surfaces 47 and 2047 can also be arranged in multiple columns along the Y-axis in a set direction of the tilt axis IA or in the X-axis direction.

[0136] In a modified example, the rotation axis 34 of the scanning mirror 32 can also be configured such that the rotation center line CM is oriented along two axes other than the Y-axis in the three-dimensional orthogonal coordinate system, or along a direction intersecting the Y-axis. In a modified example, the relationship between the directions of each axis of the three-dimensional orthogonal coordinate system and the directions of the vehicle can be appropriately specified, for example, based on the placement of the light detection device 10.

[0137] In a modified example, the lens barrel 44 may also be integrally formed with the housing 11 as part of the light-shielding shell 12. In a modified example, at least one of the aperture 442 and the light-absorbing surface 443 may not be provided in the lens barrel 44.

[0138] In a modified example, the light-receiving prisms 2049 and 4049 can also be held by the lens barrel 44 as long as they are located within the range from the individual or final light-receiving lens 43 in the light-receiving optical system 42 to the light-receiving surfaces 47 and 2047 in the light receivers 45 and 2045. In this case, the light-receiving prisms 2049 and 4049 can also constitute part of the light-receiving optical system 42.

[0139] like Figure 24 As shown, in a modified example, the incident surface 2492, which is inclined from the X-axis around the Y-axis according to the second and third embodiments, can also be applied to the light-receiving prism 4049 of the fourth embodiment. In this case, on a cross section perpendicular to the Y-axis and located on the light-receiving optical axis ROA, on the two sides sandwiching the light-receiving optical axis ROA along the X-axis direction, the side inclined towards the light-receiving optical axis ROA along the tilt axis IA1 (the light-receiving surface 47 and the emission surface 4493) and the side inclined towards the light-receiving optical axis ROA along the tilt axis IA2 can also be as follows: Figure 24 That is different or the same.

[0140] like Figure 25 As shown, in the modified example, the light-receiving units 41, 2041, 3041, and 4041 ( Figure 25 In the example of the first embodiment, a flat reflective optical filter (e.g., a bandpass filter in the near-infrared region) 1050 may also be arranged in the range from the individual or last-stage light-receiving lens 43 in the light-receiving optical system 42 to the light-receiving surface 47, 2047 in the light receiver 45, 2045.

Claims

1. A light detection device, comprising scanning an external detection area with a projected light beam and detecting reflected light beams from the detection area in relation to the projected light beam, characterized in that, have: The light-receiving optical system guides the reflected light beam along the light-receiving optical axis; The light receiver, by receiving the reflected light beam imaged by the light-receiving optical system, outputs a detection signal; as well as A light-receiving prism refracts the reflected light beam on the front side of the light receiver; The light receiver has a light-receiving surface. For this light-receiving surface, the aspect ratio of the light-receiving surface is set along a first reference axis orthogonal to the light-receiving optical axis, which is the aspect ratio of the long side. The light-receiving surface is configured to be tilted about the first reference axis relative to a second reference axis orthogonal to the light-receiving optical axis and the first reference axis. The light-receiving prism has an optical surface formed by at least one of the incident surface and the exit surface, the optical surface being configured to be tilted about the first reference axis relative to the orientation along the second reference axis.

2. A light detection device, comprising scanning an external detection area with a projected light beam and detecting reflected light beams from the detection area in relation to the projected light beam, characterized in that, have: The light-receiving optical system guides the reflected light beam along the light-receiving optical axis; The light receiver, by receiving the reflected light beam imaged by the light-receiving optical system, outputs a detection signal; as well as A light-receiving prism refracts the reflected light beam on the front side of the light receiver; The light receiver has a light-receiving surface. For this light-receiving surface, the aspect ratio of the light-receiving surface is set along a first reference axis orthogonal to the light-receiving optical axis, which is the aspect ratio of the long side. The light-receiving prism has an optical surface formed by at least one of the incident surface and the exit surface, and the optical surface is configured to be tilted about the first reference axis relative to an attitude along a second reference axis orthogonal to the light-receiving optical axis and the first reference axis.

3. The optical detection device according to claim 1 or 2, characterized in that, The light-receiving prism is attached to the light-receiving surface or held by a component different from the light-receiving prism.

4. The optical detection device according to claim 1 or 2, characterized in that, The multiple light-receiving pixels constituting the light-receiving surface are arranged in a single column along the first reference axis.

5. The optical detection device according to claim 1 or 2, characterized in that, The optical detection device also includes a scanning mirror, which scans the projected light beam toward the detection area and reflects the reflected light beam toward the light-receiving optical system. The light-receiving optical system guides the reflected beam along the light-receiving optical axis throughout the entire driving range of the scanning mirror, which is rotated about a rotation center line along the first reference axis.

6. The optical detection device according to claim 5, characterized in that, The optical detection device also includes a projector that emits the projected light beam toward the scanning mirror. The projector has a projection window, and for the projection window, the aspect ratio of the projection is set as the aspect ratio of the long side along the first reference axis.

7. The optical detection device according to claim 1 or 2, characterized in that, The light-receiving optical system has a light-receiving lens that images the reflected light beam onto the light receiver.

8. The optical detection device according to claim 7, characterized in that, The light-receiving optical system also has a lens barrel that houses the light-receiving lens.

9. The optical detection device according to claim 8, characterized in that, The lens barrel forms an aperture that narrows the exit point on the receiver side.

10. The optical detection device according to claim 8, characterized in that, The lens barrel has a light absorption surface formed around the emission outlet on the side of the light receiver to absorb the retroreflection component of the reflected light beam generated by the light receiver.

Images