Optical scanning device

Abstract

This optical scanning device is provided with: a rotary light projecting element that is rotatable about a rotation axis and that emits incident light in different directions; a rotation driving device that rotates the rotary light projecting element; a light deflection device that deflects incident light from the light source into a plane including a rotation axis and enters the rotary light projection element as deflected light; and a control device that controls the rotation drive device such that a normal line of a projection emission surface from which light is emitted from the rotary projection element is included in the plane.

Description

Technical Field

[0001] The technology of the present invention relates to an optical scanning device. Background Art

[0002] As an optical scanning device capable of scanning light such as a laser beam, a rotating laser device, a LiDAR (Light Detection And Ranging) device, and the like are known.

[0003] As a scanning method used in these optical scanning devices, a mechanical method is known in which a mechanically rotating mirror is used to deflect light (for example, refer to the specification of U.S. Patent Application Publication No. 2017 / 0269198 or Japanese Patent Publication No. 2002-039755). In addition to the mechanical method, a MEMS method is known in which a movable mirror (also called a MEMS mirror) composed of a MEMS (Micro Electro Mechanical Systems) is used to deflect light (for example, refer to the research paper "Resonant biaxial 7-mm MEMS mirror for omnidirectional scanning, J. Micro / Nanolith. MEMS MOEMS 13 (1), 011103 (Jan-Mar 2014)"). In addition, a method combining a mechanical method and a MEMS method is known (for example, refer to Japanese Patent Publication No. 2014-109686).

[0004] In such an optical scanning device, it is desirable to be able to perform not only three-dimensional optical scanning in the horizontal direction but also three-dimensional optical scanning including a vertical direction orthogonal to the horizontal direction. Summary of the invention

[0005] Technical issues to be solved by the invention

[0006] The device described in the specification of U.S. Patent Application Publication No. 2017 / 0269198 can perform three-dimensional optical scanning by mechanically rotating the light projecting element in three dimensions. However, in the device described in the specification of U.S. Patent Application Publication No. 2017 / 0269198, a rotary transformer is used to electrically connect the light projecting element and the driving device, so there is a problem that the device is large-scale and heavy.

[0007] The device described in the above research paper is a device that uses a MEMS mirror that swings in a biaxial direction and an omnidirectional optical system, and can perform optical scanning in all directions. However, in the device described in the above paper, there is a problem that the beam divergence angle becomes larger and sufficient optical performance cannot be obtained. In addition, the above research paper does not propose three-dimensional optical scanning.

[0008] The device described in Japanese Patent Application Laid-Open No. 2014-109686 can perform three-dimensional optical scanning by rotating a MEMS mirror that swings in a single axis direction. However, in the device described in Japanese Patent Application Laid-Open No. 2014-109686, a non-contact power supply unit is provided to supply power to the rotating MEMS mirror, which causes a problem of increasing the size of the device.

[0009] The device described in Japanese Patent Application Laid-Open No. 2002-039755 can perform omnidirectional optical scanning by rotating a pentaprism. The device described in Japanese Patent Application Laid-Open No. 2002-039755 does not include a non-contact power supply unit, etc., and cannot perform three-dimensional optical scanning.

[0010] Thus, the mechanical method has the advantages of high design freedom of the rotation mechanism for rotating the optical system and small beam divergence angle, but on the other hand, there is the problem of large-scale device. In addition, the MEMS method does not require a rotation mechanism, so it is conducive to miniaturization of the device, but the design freedom of the optical system is low, making it difficult to suppress the beam divergence angle.

[0011] An object of the present invention is to provide a compact optical scanning device capable of three-dimensional optical scanning.

[0012] Means for solving technical problems

[0013] In order to achieve the above-mentioned purpose, the optical scanning device of the present invention comprises: a rotating light projecting element, which can rotate around a rotation axis and emit the incident light in different directions; a rotation driving device, which rotates the rotating light projecting element; a light deflecting device, which deflects the incident light from the light source into a plane including the rotation axis and causes the incident light to be incident on the rotating light projecting element as deflected light; and a control device, which controls the rotation driving device in such a way that the normal line of the light projection surface of the light emitted from the rotating light projecting element is contained in the above-mentioned plane.

[0014] Preferably, the rotating light projecting element is a rotating light projecting reflector, and the light projecting output surface is a reflecting surface which is inclined with respect to the rotation axis and reflects the deflected light incident from the light deflecting device and outputs the deflected light.

[0015] Preferably, the rotating light projecting element is a pentaprism, and the light projecting exit surface is a light exit surface from which light that is incident from the light incident surface and is deflected by reflection in the pentaprism is emitted.

[0016] Preferably, the light deflecting device includes a biaxial scanning mirror that swings in the normal direction, and the normal line of the light projection exit surface and the normal line of the biaxial scanning mirror are located in the above-mentioned plane.

[0017] Preferably, the light deflecting device includes a beam splitter that reflects incident light from the light source and makes it incident on the biaxial scanning mirror, and allows the light reflected by the biaxial scanning mirror to pass through and be incident on the rotating light projecting element as deflected light.

[0018] Preferably, the biaxial scanning mirror is tilted with respect to the rotation axis and reflects incident light from the light source, and makes the light incident on the rotating light projecting element as deflected light.

[0019] It is preferable to further include a light receiving element that receives return light emitted from the rotating light projecting element to the outside of the device and reflected by an object.

[0020] Preferably, a perforated reflector is further provided, the perforated reflector having a hole for allowing incident light from the light source to pass therethrough and enter the light deflecting device, and the light receiving element receives return light reflected around the perforated reflector.

[0021] Preferably, the rotation driving device is a hollow motor having a through hole, and is disposed between the rotary light projecting element and the light deflecting device, and the deflected light emitted from the light deflecting device enters the rotary light projecting element through the through hole.

[0022] It is preferable to further include: a rotating light receiving element having a reflecting surface inclined with respect to the rotation axis and rotating around the rotation axis together with the rotating light projecting element; and

[0023] The light receiving element receives the return light emitted from the rotating light projecting element to the outside of the device and reflected by the object.

[0024] Preferably, the rotation drive device is a biaxial motor having a first drive shaft and a second drive shaft along the rotation axis, the rotation light receiving element is connected to the first drive shaft, and the rotation light receiving element is connected to the second drive shaft.

[0025] The preferred light deflection device is composed of: a single-axis scanning mirror, the normal direction of which swings in a direction orthogonal to the rotation axis; an image rotation prism, which causes the direction of light reflected by the single-axis scanning mirror to rotate around the rotation axis; and a hollow motor, which has a through hole on which the image rotation prism is arranged and causes the image rotation prism to rotate around the rotation axis.

[0026] Effects of the Invention

[0027] According to the technology of the present invention, it is possible to provide a compact optical scanning device capable of three-dimensional optical scanning. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1It is a perspective view showing a schematic structure of the optical scanning device according to the first embodiment.

[0029] Figure 2 It is a perspective view showing an example of a schematic structure of a movable mirror device.

[0030] Figure 3 It is a diagram showing a state where the movable reflecting mirror performs precession motion.

[0031] Figure 4 This is a diagram showing an example of a time change in the normal direction when the vertical angle is set to +2α and the laser beam is scanned in the entire circumferential direction.

[0032] Figure 5 It is a diagram showing the definition of angles around an axis.

[0033] Figure 6 This is a diagram showing an example of a time change in the normal direction when the vertical angle is set to -2α and the laser beam is scanned in the entire circumferential direction.

[0034] Figure 7 This is a perspective view showing an optical scanning device that scans a laser beam in the entire circumferential direction while setting the vertical angle to -2α.

[0035] Figure 8 This is a diagram showing an example of a time change in the normal direction when the laser beam is scanned back and forth in the vertical direction.

[0036] Fig. 9 It is a perspective view showing an optical scanning device that reciprocates and scans a laser beam in a vertical direction.

[0037] Fig.10 This is a diagram showing an example of a time change in the normal direction when the laser beam is scanned reciprocatingly in the vertical direction while scanning the laser beam in the entire circumferential direction.

[0038] Fig.11 This is a perspective view showing an optical scanning device that scans the laser beam in the entire circumferential direction while reciprocatingly scanning the laser beam in the vertical direction.

[0039] Fig.12 It is a perspective view showing a schematic structure of an optical scanning device according to a second embodiment.

[0040] Fig.13 It is a perspective view showing a schematic structure of an optical scanning device according to a second embodiment.

[0041] Fig.14 It is a perspective view showing a schematic structure of an optical scanning device according to a third embodiment.

[0042] Fig.15It is a perspective view showing a schematic structure of an optical scanning device according to a fourth embodiment.

[0043] Fig.16 It is a perspective view showing a schematic structure of an optical scanning device according to a fifth embodiment.

[0044] Fig.17 It is a perspective view showing a schematic structure of an optical scanning device according to a sixth embodiment.

[0045] Fig.18 An example of a temporal change in the rotation angle when the laser beam L is scanned in the entire circumferential direction is shown.

[0046] Fig.19 This is a diagram showing an example of a pentaprism. DETAILED DESCRIPTION

[0047] Various embodiments of the technology of the present invention will be described with reference to the drawings.

[0048] [First embodiment]

[0049] Figure 1 The schematic configuration of the optical scanning device 2 according to the first embodiment is shown. The optical scanning device 2 according to the first embodiment is used as, for example, a rotary laser device.

[0050] like Figure 1 As shown, the optical scanning device 2 includes a rotating light projection mirror 3, a motor 4, a light deflection device 5, and a control device 6. The rotating light projection mirror 3 is an example of a "rotating light projection element" involved in the technology of the present invention. The motor 4 is an example of a "rotation driving device" involved in the technology of the present invention.

[0051] The rotating light projection reflector 3 has a reflecting surface 3A inclined with respect to the rotation axis C and is rotatable about the rotation axis C. The reflecting surface 3A is inclined at an angle of 45° with respect to the rotation axis C. That is, the angle formed by the normal line N2 of the reflecting surface 3A and the rotation axis C is 45°.

[0052] The rotating light projection reflector 3 is connected to a driving shaft 4A of a motor 4 . The motor 4 drives the rotating light projection reflector 3 to rotate the rotating light projection reflector 3 around a rotation axis C. The motor 4 is controlled by a control device 6 .

[0053] Hereinafter, a direction parallel to the rotation axis C is referred to as a Z-axis direction, a direction perpendicular to the Z-axis direction is referred to as an X-axis direction, and a direction perpendicular to the Z-axis direction and the X-axis direction is referred to as a Y-axis direction.

[0054] The light deflection device 5 deflects the incident light from the light source 7 and makes it incident on the reflection surface 3A of the rotating light projection reflector 3 as deflected light. The light source 7 is, for example, a laser diode. The light deflection device 5 includes a biaxial scanning mirror 10, a beam splitter 11 and a λ / 4 phase difference plate 12. The biaxial scanning mirror 10, the beam splitter 11 and the λ / 4 phase difference plate 12 are arranged on the rotation axis C. In addition, as the light source 7, various lasers other than laser diodes (DPSS (Diode Pumped Solid State: diode pumped solid state) laser, fiber laser, etc.), LED (Light Emitting Diode: light emitting diode), etc. can be used. In addition, as the light source 7, electromagnetic wave lasers with longer wavelengths (millimeter wave radar, etc.) can also be used.

[0055] The biaxial scanning mirror 10 is disposed on the rotation axis C and at a position facing the reflection surface 3A of the rotating light projecting mirror 3. The beam splitter 11 is disposed between the rotating light projecting mirror 3 and the biaxial scanning mirror 10. The λ / 4 phase difference plate 12 is disposed between the beam splitter 11 and the biaxial scanning mirror 10.

[0056] In the beam splitter 11, the laser beam L is incident from the light source 7 via the collimator lens 8. The beam splitter 11 is a polarization beam splitter, and the laser beam L is incident on the beam splitter 11 as, for example, S-polarized light. The beam splitter 11 reflects the laser beam L incident from the light source 7. The laser beam L reflected by the beam splitter 11 is incident on the biaxial scanning mirror 10 via the λ / 4 phase difference plate 12. The laser beam L travels along the rotation axis C and is incident on the biaxial scanning mirror 10. In addition, the laser beam L is an example of "light" involved in the technology of the present invention.

[0057] The biaxial scanning mirror 10 deflects the laser beam L by reflecting the laser beam L. The details will be described later. The biaxial scanning mirror 10 is controlled by the control device 6 with a movable reflection mirror 20 (refer to Figure 2 ) is controlled in a manner that allows the precession motion to be performed in the same period as the rotating light projection reflector 3.

[0058] The laser beam L reflected by the biaxial scanning mirror 10 passes through the λ / 4 phase difference plate 12, thereby entering the beam splitter 11 as P polarized light. Therefore, the laser beam L entering the beam splitter 11 from the biaxial scanning mirror 10 passes through the beam splitter 11 and enters the reflection surface 3A of the rotating projection reflection mirror 3 as deflected light.

[0059] The laser beam L incident on the reflection surface 3A is reflected by the reflection surface 3A and emitted in the circumferential direction around the rotation axis C. The laser beam L is scanned in a circular orbit by the rotation of the rotating projection reflector 3. Figure 3) and the rotation axis C are set to α, the angle of the laser beam L in the vertical direction (Z-axis direction) relative to the horizontal plane (XY plane) (hereinafter referred to as the vertical angle) is 2α. Therefore, the vertical angle of the laser beam L scanned around the rotating projection reflector 3 is determined by the angle of the normal line N1.

[0060] The control device 6 controls the operation of the rotating light projection reflecting mirror 3 and the biaxial scanning mirror 10. The control device 6 is a processor constituted by an IC (Integrated Circuit) or the like. Alternatively, the control device 6 may be a processor that executes processing according to a program.

[0061] Figure 2 The schematic structure of the biaxial scanning mirror 10 is shown. The biaxial scanning mirror 10 is a micro mirror device formed by etching an SOI (Silicon On Insulator) substrate.

[0062] The biaxial scanning mirror 10 includes a movable reflecting mirror 20 , a first supporting portion 21 , a first movable frame 22 , a second supporting portion 23 , a second movable frame 24 , a connecting portion 25 , and a fixed frame 26 .

[0063] The movable reflector 20 has a reflective surface 20A that reflects incident light. The reflective surface 20A is formed of a metal thin film such as gold (Au), aluminum (Al), silver (Ag), or an alloy of silver, which is provided on one side of the movable reflector 20. The shape of the reflective surface 20A is, for example, a circular shape centered at the intersection of the a1 axis and the a2 axis. For example, the a1 axis is parallel to the X-axis direction, and the a2 axis is parallel to the Y-axis direction.

[0064] The first support parts 21 are respectively arranged outside the movable reflector 20 and at positions opposite to each other across the a2 axis. The first support parts 21 are connected to the movable reflector 20 on the a1 axis and support the movable reflector 20 so that it can swing around the a1 axis. In the present embodiment, the first support parts 21 are torsion bars extending along the a1 axis.

[0065] The first movable frame 22 is a rectangular frame body surrounding the movable reflector 20, and is connected to the movable reflector 20 on the a1 axis via the first support portion 21. Piezoelectric elements 30 are formed at positions opposite to each other across the a1 axis on the first movable frame 22. Thus, by forming two piezoelectric elements 30 on the first movable frame 22, a pair of first actuators 31 are formed.

[0066] The pair of first actuators 31 are disposed at positions facing each other across the a1 axis. The first actuators 31 cause a torque about the a1 axis to act on the movable mirror 20, thereby causing the movable mirror 20 to swing about the a1 axis.

[0067] The second support parts 23 are respectively arranged at positions opposite to the first movable frame 22 on the outside and across the a1 axis. The second support parts 23 are connected to the first movable frame 22 on the a2 axis, and support the first movable frame 22 and the movable reflector 20 so that they can swing around the a2 axis. In the present embodiment, the second support parts 23 are torsion bars extending along the a2 axis.

[0068] The second movable frame 24 is a rectangular frame body surrounding the first movable frame 22, and is connected to the first movable frame 22 on the a2 axis via the second support portion 23. Piezoelectric elements 30 are formed at positions opposite to each other across the a2 axis on the second movable frame 24. In this way, by forming two piezoelectric elements 30 on the second movable frame 24, a pair of second actuators 32 are formed.

[0069] The pair of second actuators 32 are disposed at positions facing each other across the a2 axis. The second actuators 32 cause a torque about the a2 axis to act on the movable mirror 20 and the first movable frame 22, thereby causing the movable mirror 20 to swing about the a2 axis.

[0070] The connection parts 25 are respectively arranged at positions facing the second movable frame 24 on the outer side and across the a1 axis. The connection parts 25 are connected to the second movable frame 24 on the a2 axis.

[0071] The fixed frame 26 is a rectangular frame body surrounding the second movable frame 24 , and is connected to the second movable frame 24 via the connection portion 25 on the a2 axis.

[0072] The pair of first actuators 31 and the pair of second actuators 32 function as a driving unit that drives the movable reflecting mirror 20 .

[0073] In the present embodiment, the control device 6 causes the movable reflector 20 to perform precession motion by applying sinusoidal drive voltages having different phases to the pair of first actuators 31 and the pair of second actuators 32. In other words, the control device 6 causes the direction of the normal line N1 to swing within a plane including the rotation axis C and the X-axis. The direction of the normal line N1 is swung in the X-axis direction and the Y-axis direction, and the phase difference between the two is set to 90°, thereby causing the normal line N1 to move in a manner of describing a circle.

[0074] Figure 3 Indicates a situation where the movable reflector 20 performs precession motion. Precession motion refers to a motion in which the normal line N1 of the reflection surface 20A of the movable reflector 20 swings in a circular manner. That is, the movable reflector 20 rotates in a state where the direction of the normal line N1 is tilted at an angle α relative to the rotation axis C. In addition, the movable reflector 20 is configured so that the rotation axis C passes through its center. In the present embodiment, the direction of the normal line N1 of the movable reflector 20 when it is not tilted is parallel to the rotation axis C.

[0075] The laser beam L incident on the biaxial scanning mirror 10 from the beam splitter 11 via the λ / 4 phase difference plate 12 is incident on the center of the movable reflection mirror 20 along the rotation axis C. Figure 3 As shown, the laser beam L deflected by the movable reflecting mirror 20 performing the precession motion is emitted from the movable reflecting mirror 20 so as to draw a circle.

[0076] Figure 4 An example of a time change in the normal direction when the laser beam L is scanned in the entire circumferential direction with the vertical angle set to +2α is shown. Figure 4 (A) shows the time variation of the normal direction of the biaxial scanning mirror 10 . Figure 4 (B) shows the time variation of the normal direction of the rotating projection mirror 3. The normal direction of the biaxial scanning mirror 10 refers to the direction of the normal line N1 of the reflection surface 20A. The normal direction of the rotating projection mirror 3 refers to the direction of the normal line N2 of the reflection surface 3A. Figure 4 In FIG. 1 , the directions of the normal lines N1 and N2 are represented by using the angle θx around the X-axis, the angle θy around the Y-axis, and the angle θz around the Z-axis as parameters. Figure 5 Indicates the definition of angles θx, θy, and θz.

[0077] exist Figure 4 In θz1 and θz2, θz1 and θz2 represent the angles θz of the normal lines N1 and N2 at a certain point in time. Figure 4 The radius of rotation of the normal N1 in depends on the angle α.

[0078] exist Figure 4 In the example shown, the control device 6 controls the movement of the rotating light projection reflector 3 and the biaxial scanning mirror 10 in such a manner that θz1=θz2 is set and the angle α is set constant. As a result, the movable reflector 20 performs precession motion with the same period and phase as the rotation of the rotating light projection reflector 3. As a result, the vertical angle of the laser beam L scanned around the rotating light projection reflector 3 becomes +2α (reference Figure 1 ).

[0079] Figure 6 An example of a time change in the normal direction when the laser beam L is scanned in the entire circumferential direction with the vertical angle set to -2α is shown. Figure 6 (A) shows the time variation of the normal direction of the biaxial scanning mirror 10 . Figure 6 (B) shows the time variation of the normal direction of the rotating light projection reflector 3.

[0080] exist Figure 6In the example shown, the control device 6 controls the movement of the rotating light projection reflector 3 and the biaxial scanning mirror 10 in such a manner that θz1-θz2=180° and the angle α is set constant. As a result, the movable reflector 20 performs precession motion with the same period and in the opposite phase as the rotation of the rotating light projection reflector 3. Figure 7 As shown, the vertical angle of the laser beam L scanned around the rotating projection reflector 3 becomes -2α.

[0081] As described above, the control device 6 controls the light deflection device 5 so that the incident light from the light source 7 is deflected into the plane including the rotation axis C and is incident on the reflection surface 3A as deflected light. Furthermore, the control device 6 controls the motor 4 so that the normal line N2 of the reflection surface 3A is included in the plane. In this embodiment, the normal line N1 and the normal line N2 are in the plane. That is, the rotation axis C, the normal line N1 and the normal line N2 are included in the plane.

[0082] The optical scanning device 2 of this embodiment performs scanning by reflecting the laser beam L deflected by the optical deflection device 5 by the reflection surface 3A of the rotating light projection reflector 3, so it is small and can perform three-dimensional optical scanning. In addition, the optical scanning device 2 scans the laser beam L by reflecting it by the reflection surface 3A, so the beam divergence angle of the laser beam L can be suppressed.

[0083] Next, a modification of the first embodiment will be described. The following modification differs from the first embodiment only in the scanning method of the laser beam L, and the structure of the optical scanning device 2 is the same as that of the first embodiment.

[0084] Figure 8 An example of a time change in the normal direction when the laser beam L is scanned back and forth in the vertical direction is shown. Figure 8 (A) shows the time variation of the normal direction of the biaxial scanning mirror 10 . Figure 8 (B) shows the time variation of the normal direction of the rotating light projection reflector 3.

[0085] In this modification, the control device 6 controls the biaxial scanning mirror 10 in such a manner that the angle between the direction of the normal line N1 and the rotation axis C changes within the range of ±α, while the rotation of the rotating light projection reflector 3 is stopped and θz1=θz2. That is, the control device 6 controls the biaxial scanning mirror 10 in such a manner that the normal line N1 swings within a plane including the rotation axis C and the normal line N2.

[0086] like Fig. 9 As shown, in this modification, the laser beam L is reciprocatedly scanned in the vertical direction within a range of ±2α.

[0087] Fig.10An example of a time change in the normal direction when the laser beam L is scanned back and forth in the vertical direction while scanning the laser beam L in the entire circumferential direction is shown. Fig.10 (A) shows the time variation of the normal direction of the biaxial scanning mirror 10 . Fig.10 (B) shows the time variation of the normal direction of the rotating light projection reflector 3.

[0088] In this modification, the control device 6 controls the biaxial scanning mirror 10 in such a manner that the angle between the direction of the normal line N1 and the rotation axis C changes within the range of ±α while rotating the rotating light projection reflector 3 and setting θz1=θz2. That is, the control device 6 controls the biaxial scanning mirror 10 in such a manner that the normal line N1 swings within a plane including the rotation axis C and the normal line N2.

[0089] like Fig.11 As shown, in this modification, the laser beam L is scanned in the entire circumferential direction, and the laser beam L is reciprocated in the vertical direction within the range of ±2α.

[0090] In this modification, the control device 6 causes the movable reflection mirror 20 of the biaxial scanning mirror 10 to precess while swinging the direction of the normal line N1, so that Fig.10 As shown in (A), the swing direction of the normal line N1 may deviate from the plane including the rotation axis C and the normal line N2. In contrast, the control device 6 can make the swing direction of the normal line N1 within the plane including the rotation axis C and the normal line N2 by correcting the drive voltage supplied to the biaxial scanning mirror 10.

[0091] [Second embodiment]

[0092] Next, a second embodiment will be described. Fig.12 and Fig.13 The schematic structure of the optical scanning device 2A involved in the second embodiment is shown. The beam splitter 11 and the λ / 4 phase difference plate 12 are not provided in the optical scanning device 2A. That is, in this embodiment, the optical deflection device 5 is composed of only the biaxial scanning mirror 10. The biaxial scanning mirror 10 is inclined relative to the rotation axis C so that the incident light from the light source 7 is deflected and emitted as deflected light toward the reflection surface 3A of the rotating projection reflector 3. When the biaxial scanning mirror 10 is not driven, the angle between the normal line N1 and the rotation axis C is, for example, 45°.

[0093] In this embodiment, the optical scanning device 2A includes a perforated reflector 13, a light receiving element 14, and a light receiving lens 15, and is configured as a three-dimensional scanner sensor such as a LiDAR device. The perforated reflector 13 has a hole 13A that allows incident light from the light source 7 to pass through and enter the biaxial scanning mirror 10. The perforated reflector 13 is arranged between the collimating lens 8 and the biaxial scanning mirror 10.

[0094] The laser beam L emitted from the light source 7 passes through the hole 13A of the perforated reflector 13 via the collimator lens 8 and enters the biaxial scanning mirror 10 at an incident angle of 45°. The laser beam L entering the biaxial scanning mirror 10 is reflected by the movable reflector 20 and enters the reflection surface 3A of the rotating projection reflector 3.

[0095] In this embodiment as well, the control device 6 controls the light deflection device 5 so that the incident light from the light source 7 is deflected into a plane including the rotation axis C and is incident on the reflection surface 3A as deflected light. Furthermore, the control device 6 controls the motor 4 so that the normal line N2 of the reflection surface 3A is included in the plane. The scanning method is the same as that of the first embodiment or each modified example of the first embodiment.

[0096] The light receiving element 14 receives the return light Lr emitted from the optical scanning device 2A to the outside of the device and reflected by the object. Specifically, the return light Lr is reflected by the reflection surface 3A and incident on the biaxial scanning mirror 10. The light receiving element 14 receives the return light Lr reflected by the reflection surface 13B around the hole 13A of the perforated reflector 13 after being reflected by the biaxial scanning mirror 10 through the light receiving lens 15. The light receiving element 14 is a photodiode, an avalanche photodiode (APD), a single photon avalanche diode (SPAD), etc.

[0097] The optical scanning device 2A involved in this embodiment does not include the beam splitter 11 and the λ / 4 phase difference plate 12, so it can be further miniaturized. In addition, since the return light Lr is guided to the light receiving element 14 using the perforated reflector 13, the influence of stray light caused by the laser beam L other than the return light Lr can be suppressed compared to the case where the return light Lr is guided to the light receiving element 14 using a half mirror or the like.

[0098] In the present embodiment, the return light Lr is guided to the light receiving element 14 using the perforated mirror 13 . However, the return light Lr may be guided to the light receiving element 14 using a beam splitter instead of the perforated mirror 13 .

[0099] Furthermore, by applying the perforated mirror 13 , the light receiving element 14 , and the light receiving lens 15 of this embodiment to the first embodiment, the optical scanning device 2 according to the first embodiment can also be configured as a three-dimensional scanner sensor.

[0100] [Third Embodiment]

[0101] Next, a third embodiment will be described. Fig.14 The schematic configuration of an optical scanning device 2B according to the third embodiment is shown. The optical scanning device 2B is different from the optical scanning device 2 according to the first embodiment only in that a hollow motor 40 is provided instead of the motor 4 .

[0102] The hollow motor 40 has a through hole 41 and is disposed between the rotating light projecting reflector 3 and the light deflecting device 5. The rotating light projecting reflector 3 is mounted on a rotating portion 42 of the hollow motor 40. The laser beam L emitted as deflected light from the light deflecting device 5 passes through the through hole 41 and enters the reflecting surface 3A of the rotating light projecting reflector 3.

[0103] The operations of the hollow motor 40 and the biaxial scanning mirror 10 are controlled by the control device 6. The scanning method is the same as that of the first embodiment or each modified example of the first embodiment.

[0104] In this embodiment, the hollow motor 40 is provided on the light deflection device 5 side of the rotating light projecting reflector 3 . Therefore, there is an advantage that the electrical connection from the control device 6 to the hollow motor 40 does not block the laser beam L emitted from the rotating light projecting reflector 3 .

[0105] In the first and second embodiments, the motor 4 is provided on the side of the rotating light projection reflector 3 opposite to the light deflection device 5, so the electrical connection from the control device 6 to the motor 4 may block the laser beam L emitted from the rotating light projection reflector 3. However, this will not be a problem when the laser beam L is scanned in the circumferential direction within a range less than 360°. Furthermore, by adopting a non-contact power supply method, using a transparent electrode, etc., the electrical connection can be performed without blocking the laser beam L.

[0106] [Fourth embodiment]

[0107] Next, a fourth embodiment will be described. Fig.15 The schematic configuration of an optical scanning device 2C according to the fourth embodiment is shown. The optical scanning device 2C includes a rotating light receiving reflective mirror 50 , a light receiving element 14 , and a light receiving lens 15 in addition to the configuration of the optical scanning device 2B according to the third embodiment.

[0108] The rotating light receiving reflector 50 is connected to the side of the rotating light projecting reflector 3 opposite to the hollow motor 40, and rotates together with the rotating light projecting reflector 3 about the rotation axis C. The rotating light receiving reflector 50 has a reflecting surface 51 inclined with respect to the rotation axis C. The rotating light receiving reflector 50 is arranged so that the normal line of the reflecting surface 51 is included in the plane including the rotation axis C and the normal line N2.

[0109] The reflection surface 51 reflects the return light Lr emitted from the optical scanning device 2C to the outside of the device and reflected by an object to return. The rotating light receiving reflector 50 is an example of a “rotating light receiving element” according to the technique of the present invention.

[0110] The light receiving element 14 and the light receiving lens 15 are arranged on the rotation axis C. The light receiving element 14 receives the return light Lr reflected by the reflection surface 51 via the light receiving lens 15 .

[0111] The operations of the hollow motor 40 and the biaxial scanning mirror 10 are controlled by the control device 6. The scanning method is the same as that of the first embodiment or each modified example of the first embodiment.

[0112] In this embodiment, since the light projection by the rotating light projection reflector 3 and the light reception by the rotating light reception reflector 50 are performed on different optical axes, the light receiving element 14 does not receive the laser beam L. That is, the light receiving element 14 further suppresses the influence of stray light caused by the laser beam L other than the return light Lr.

[0113] [Fifth embodiment]

[0114] Next, a fifth embodiment will be described. Fig.16 The schematic structure of the optical scanning device 2D according to the fifth embodiment is shown. The optical scanning device 2D is different from the optical scanning device 2 according to the first embodiment only in that a biaxial motor 60 is provided instead of the motor 4. In addition, the optical scanning device 2D is provided with a rotating light receiving reflector 50, a light receiving element 14, and a light receiving lens 15, similarly to the fourth embodiment.

[0115] The biaxial motor 60 has a first drive shaft 61 and a second drive shaft 62 along the rotation axis C. The first drive shaft 61 is arranged on the optical deflection device 5 side of the biaxial motor 60. The second drive shaft 62 is arranged on the opposite side of the biaxial motor 60 from the optical deflection device 5. The rotating light projecting reflector 3 is connected to the first drive shaft 61. The rotating light receiving reflector 50 is connected to the second drive shaft 62.

[0116] By driving the biaxial motor 60, the rotating light receiving reflector 50 rotates together with the rotating light projecting reflector 3 about the rotation axis C. As in the fourth embodiment, the rotating light receiving reflector 50 is arranged so that the normal line of the reflecting surface 51 is included in the plane including the rotation axis C and the normal line N2.

[0117] The operations of the biaxial motor 60 and the biaxial scanning mirror 10 are controlled by the control device 6. The scanning method is the same as that of the first embodiment or each modified example of the first embodiment.

[0118] In this embodiment, since the biaxial motor 60 is used, the thickness of the optical scanning device 2D in the Z-axis direction can be reduced, thereby shortening the distance between the biaxial scanning mirror 10 and the rotating light receiving reflection mirror 50 .

[0119] [Sixth embodiment]

[0120] Next, a sixth embodiment will be described. Fig.17The schematic structure of the optical scanning device 2E involved in the sixth embodiment is shown. The optical scanning device 2E is equipped with a uniaxial scanning mirror 10A instead of the biaxial scanning mirror 10. In addition, an image rotation prism 70 and a hollow motor 80 are added to the optical scanning device 2E. In this embodiment, the optical deflection device 5 is composed of the uniaxial scanning mirror 10A, the beam splitter 11, the λ / 4 phase difference plate 12, the image rotation prism 70 and the hollow motor 80.

[0121] The uniaxial scanning mirror 10A is configured so that the normal direction thereof swings in a direction perpendicular to the rotation axis C. For example, the uniaxial scanning mirror 10A is a MEMS mirror in which the normal direction thereof swings in the X-axis direction by swinging the movable mirror 20 about the a2-axis.

[0122] The hollow motor 80 has a through hole 81 and is disposed between the rotating light projection reflector 3 and the light deflection device 5. The image rotation prism 70 is disposed in the through hole 81 and is mounted on the rotating portion 82 of the hollow motor 80. The laser beam L emitted as deflected light from the light deflection device 5 is incident on one end of the image rotation prism 70 and is emitted from the other end of the image rotation prism 70. The laser beam L emitted from the other end of the image rotation prism 70 is incident on the reflection surface 3A of the rotating light projection reflector 3.

[0123] The image rotation prism 70 is a double prism that rotates the direction of the incident laser beam L around the rotation axis C. The hollow motor 80 rotates the image rotation prism 70 around the rotation axis C. When the image rotation prism 70 rotates, the direction of the laser beam L rotates at an angular velocity twice that of the image rotation prism 70 .

[0124] In this embodiment, the uniaxial scanning mirror 10A deflects the laser beam L in a uniaxial direction, and the image rotation prism 70 rotates the direction of the laser beam L deflected by the uniaxial scanning mirror 10A, thereby deflecting the laser beam L in biaxial directions.

[0125] The operation of the motor 4, the hollow motor 80, and the uniaxial scanning mirror 10A is controlled by the control device 6. In the present embodiment, the control device 6 rotates the rotating light projection reflector 3 at an angular velocity twice that of the image rotation prism 70. Thus, while the rotating light projection reflector 3 is rotated, the laser beam L emitted from the image rotation prism 70 as deflected light can be incident on the reflection surface 3A along a plane including the rotation axis C and the normal line N2.

[0126] Fig.18 An example of a temporal change in the rotation angle when the laser beam L is scanned in the entire circumferential direction is shown. Fig.18 (A) shows the time change of the rotation angle of the image rotation prism 70. Fig.18(B) shows the time variation of the rotation angle of the rotating light projection reflecting mirror 3. In the present embodiment, θz1 shows the angle θz of the image rotation prism 70 around the Z axis. θz2 shows the angle θz of the rotating light projection reflecting mirror 3 around the Z axis.

[0127] exist Fig.18 In the example shown, the driving of the motor 4 and the hollow motor 80 is controlled to maintain the relationship 2×θz1=θz2 without swinging the uniaxial scanning mirror 10A and keeping the angle between the rotation axis C and the normal line N1 constant. Thus, the laser beam L scans in the entire circumferential direction.

[0128] Furthermore, by swinging the uniaxial scanning mirror 10A, the laser beam L can be scanned in the entire circumferential direction and reciprocated in the vertical direction.

[0129] In the present embodiment, three-dimensional optical scanning can be performed using the uniaxial scanning mirror 10A having a simple structure.

[0130] [Other embodiments]

[0131] In each of the above-described embodiments, the rotating light projection reflector 3 is used as the rotating light projection element. However, a pentaprism may be used instead of the rotating light projection reflector 3 .

[0132] Fig.19 An example of a pentaprism is shown. Fig.19 As shown, the pentaprism 90 deflects the incident laser beam L by 90° and emits it. Specifically, the pentaprism 90 has a light incident surface 91 and a light exit surface 92. The laser beam L emitted as deflected light from the light deflection device 5 is incident on the light incident surface 91. The laser beam L incident on the light incident surface 91 is reflected twice inside the pentaprism 90 and is emitted from the light exit surface 92.

[0133] The light deflection device 5 deflects the laser beam L into a plane including the rotation axis C and makes the laser beam incident as deflected light on the light incident surface 91. The pentaprism 90 rotates around the rotation axis C so that the normal line N2 of the light emitting surface 92 is included in the plane.

[0134] In this way, the rotating light-projecting reflector 3 and the pentaprism 90 are both rotating light-projecting elements that can rotate around the rotation axis C and emit the incident light in different directions. In the present invention, the light deflection device 5 deflects the incident light from the light source 7 into a plane including the rotation axis C and causes the light to be incident on the rotating light-projecting element as deflected light. The control device 6 controls the rotation drive device such as the motor 4 in such a way that the normal of the surface from which the light is emitted from the rotating light-projecting element (hereinafter referred to as the light-projecting exit surface) is included in the plane. In the case where the rotating light-projecting element is the rotating light-projecting reflector 3, the light-projecting exit surface is the reflecting surface 3A. In the case where the rotating light-projecting element is the pentaprism 90, the light-projecting exit surface is the light-exit surface 92.

[0135] Furthermore, a 45° right angle prism can be used as the rotating light projecting element. In this case, the right angle prism is configured so that the reflecting surface forms an angle of 45° with the rotation axis C. Furthermore, a right angle prism having an angle other than 45° can also be used as the rotating light projecting element.

[0136] The above-mentioned embodiments and modifications can be combined as appropriate unless conflicts arise.

[0137] According to the optical scanning device of the present invention, as long as it is within the range where optical scanning can be performed, it is possible to focus on and scan light within any limited range. Furthermore, when the optical scanning device of the present invention is applied to devices such as LiDAR and radar, it is also expected that by performing optical scanning within the range of interest, effects such as improving resolution or increasing scanning rate can be achieved.

[0138] All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each individual document, patent application, or technical standard was specifically and individually described as being incorporated by reference.

[0139] Through the above description, the following techniques can be mastered.

[0140] [Supplementary Item 1]

[0141] An optical scanning device comprising:

[0142] The rotating light-projecting element can rotate around the rotation axis and emit the incident light in different directions;

[0143] A rotation driving device for rotating the rotating light projecting element;

[0144] a light deflecting device for deflecting incident light from a light source into a plane including the rotation axis and causing the light to enter the rotating light projecting element as deflected light; and

[0145] The control device controls the rotation drive device in such a manner that a normal line of a light projection surface of light emitted from the rotating light projection element is included in the plane.

[0146] [Supplementary Item 2]

[0147] The optical scanning device according to Supplementary item 1, wherein:

[0148] The rotating light-projecting element is a rotating light-projecting reflector.

[0149] The light projection output surface is a reflection surface that is inclined with respect to the rotation axis and reflects the deflected light incident from the light deflecting device and outputs the deflected light.

[0150] [Supplementary item 3]

[0151] The optical scanning device according to supplementary item 2, wherein:

[0152] The rotating light-projecting element is a pentaprism.

[0153] The light projection exit surface is a light exit surface from which light that is incident from the light incident surface and is deflected by reflection in the pentaprism is emitted.

[0154] [Supplementary Item 4]

[0155] The optical scanning device according to Supplementary item 1 or 2, wherein:

[0156] The light deflection device comprises a biaxial scanning mirror that swings in the normal direction.

[0157] The normal line of the light projection exit surface and the normal line of the biaxial scanning mirror are within the plane.

[0158] [Supplementary Item 5]

[0159] The optical scanning device according to supplementary item 4, wherein:

[0160] The light deflecting device includes a beam splitter that reflects incident light from the light source and makes it incident on the biaxial scanning mirror, and allows the light reflected by the biaxial scanning mirror to pass through and be incident on the rotating light projecting element as the deflected light.

[0161] [Supplementary Item 6]

[0162] The optical scanning device according to Supplementary item 4 or 5, wherein:

[0163] The two-axis scanning mirror is inclined with respect to the rotation axis and reflects incident light from the light source, and the reflected light is incident on the rotating light projecting element as the deflected light.

[0164] [Supplementary Item 7]

[0165] The optical scanning device according to any one of Supplementary Notes 1 to 6, further comprising a light receiving element that receives return light emitted from the rotating light projecting element to the outside of the device and reflected by an object and returned.

[0166] [Supplementary Item 8]

[0167] The optical scanning device according to Supplementary item 7 further comprises a perforated reflector having a hole through which incident light from the light source passes and enters the light deflecting device,

[0168] The light receiving element receives the return light reflected around the perforated reflector.

[0169] [Supplementary Item 9]

[0170] The optical scanning device according to any one of Supplementary Items 1 to 8, wherein:

[0171] The rotation drive device is a hollow motor having a through hole and is arranged between the rotating light projecting element and the light deflecting device.

[0172] The deflected light emitted from the light deflecting device passes through the through hole and enters the rotating light projecting element.

[0173] [Supplementary Item 10]

[0174] The optical scanning device according to any one of Supplementary Items 1 to 9, further comprising:

[0175] a rotating light receiving element having a reflecting surface inclined relative to the rotation axis and rotating together with the rotating light projecting element around the rotation axis; and

[0176] The light receiving element receives the return light emitted from the rotating light projecting element to the outside of the device and reflected by the object.

[0177] [Supplementary Item 11]

[0178] The optical scanning device according to supplementary item 10, wherein:

[0179] The rotation drive device is a dual-axis motor having a first drive axis and a second drive axis along the rotation axis.

[0180] The rotating light projecting element is connected to the first driving shaft.

[0181] The rotating light receiving element is connected to the second driving shaft.

[0182] [Supplementary Item 12]

[0183] The optical scanning device according to any one of Supplementary Notes 1 to 11, wherein:

[0184] The light deflection device is composed of:

[0185] A single-axis scanning mirror, the normal direction of which swings in a direction orthogonal to the rotation axis;

[0186] An image rotation prism that rotates the direction of the light reflected by the uniaxial scanning mirror around the rotation axis; and

[0187] The hollow motor has a through hole in which the image rotation prism is disposed, and rotates the image rotation prism around the rotation axis.

Claims

1. An optical scanning device comprising: A rotating light-projecting element that can rotate around a rotation axis and emit incident light in different directions; A rotation driving device, which rotates the rotating light projecting element; a light deflecting device that deflects incident light from a light source in a plane including the rotation axis and causes the light to enter the rotating light projecting element as deflected light; and A control device controls the rotation drive device in such a manner that a normal line of a light projection output surface of light emitted from the rotating light projection element is included in the plane.

2. The optical scanning device according to claim 1, wherein: The rotating light-projecting element is a rotating light-projecting reflector. The light projection output surface is a reflection surface that is inclined with respect to the rotation axis and reflects the deflected light incident from the light deflecting device and outputs the deflected light.

3. The optical scanning device according to claim 2, wherein: The rotating light-projecting element is a pentaprism. The light projection exit surface is a light exit surface that allows light that is incident from the light incident surface and is deflected by reflection in the pentaprism to exit.

4. The optical scanning device according to claim 1, wherein: The light deflection device comprises a biaxial scanning mirror that swings in the normal direction. The normal line of the light projection exit surface and the normal line of the biaxial scanning mirror are within the plane.

5. The optical scanning device according to claim 4, wherein: The light deflecting device includes a beam splitter that reflects incident light from the light source and makes it incident on the biaxial scanning mirror, and allows the light reflected by the biaxial scanning mirror to pass through and be incident on the rotating light projecting element as the deflected light.

6. The optical scanning device according to claim 4, wherein: The two-axis scanning mirror is inclined with respect to the rotation axis, and reflects incident light from the light source and makes the light incident on the rotating light projecting element as the deflected light.

7. The optical scanning device according to claim 1, wherein: The optical scanning device further includes a light receiving element that receives return light emitted from the rotating light projecting element to the outside of the device and reflected by an object to return.

8. The optical scanning device according to claim 7, wherein: The optical scanning device further includes a perforated reflector having a hole for allowing incident light from the light source to pass therethrough and enter the light deflecting device. The light receiving element receives the return light reflected around the perforated reflector.

9. The optical scanning device according to claim 1, wherein: The rotation drive device is a hollow motor having a through hole and is arranged between the rotating light projecting element and the light deflecting device. The deflected light emitted from the light deflecting device passes through the through hole and enters the rotating light projecting element.

10. The optical scanning device according to claim 1, wherein: The optical scanning device also has: a rotating light receiving element having a reflecting surface inclined relative to the rotation axis and rotating with the rotating light projecting element around the rotation axis; and The light receiving element is configured such that the return light emitted from the rotating light projecting element to the outside of the device and reflected by an object and returned is reflected by the rotating light receiving element and received by the light receiving element.

11. The optical scanning device according to claim 10, wherein: The rotation drive device is a dual-axis motor having a first drive axis and a second drive axis along the rotation axis. The rotating light projecting element is connected to the first driving shaft. The rotating light receiving element is connected to the second driving shaft.

12. The optical scanning device according to claim 1, wherein: The light deflection device is composed of: A single-axis scanning mirror, the normal direction of which swings in a direction orthogonal to the rotation axis; an image rotation prism that rotates the direction of the light reflected by the uniaxial scanning mirror about the rotation axis; and The hollow motor has a through hole in which the image rotation prism is disposed, and rotates the image rotation prism around the rotation axis.

Images