Optical Scanning Device and Distance Measuring Device

Abstract

The optical scanning device (2) is configured to include: an optical mode converter (5) that changes the emission direction of light in accordance with a change in the wavelength of the light output from the light source (1) or a change in the phase of the light output from the light source (1); and an actuator (7) that rotates the optical mode converter (5) about two perpendicular axes, respectively.

Description

Technical Field

[0001] The present invention relates to an optical scanning device and a distance measuring device having the optical scanning device, and the optical scanning device is configured to reflect light that is reflected by a distance measuring object after being emitted toward the distance measuring object. Background Art

[0002] Among distance measuring devices, there are distance measuring devices having an optical scanning device configured to reflect light that is reflected by a distance measuring object after being emitted toward the distance measuring object.

[0003] A MEMS (Micro ElectroMechanical Systems) scanner that can be used as the optical scanning device is disclosed in Patent Document 1 below.

[0004] The MEMS scanner has a mirror configured to reflect light output from a light source toward a distance measuring object and then reflect the light reflected by the distance measuring object toward a light receiver. Further, the MEMS scanner has an actuator configured to rotate the mirror about a first axis and rotate the mirror about a second axis.

[0005] When light is output from the light source toward the mirror, if the actuator rotates the mirror about two axes as described below, for example, optical scanning of the distance measuring object can be performed.

[0006] First, the actuator changes the rotation angle θx about the first axis from θx1 to θx2, and then changes the rotation angle θy about the second axis by Δθ (hereinafter referred to as “first rotation operation”). Next, the actuator changes the rotation angle θx about the first axis from θx2 to θx1, and then changes the rotation angle θy about the second axis by Δθ (hereinafter referred to as “second rotation operation”). Then, the actuator alternately repeats the first rotation operation and the second rotation operation.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-522529 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] The resolution of optical scanning for a distance measuring object depends on the magnitude of Δθ. The smaller Δθ is, the higher the resolution of optical scanning becomes. However, due to the mechanical structure of the actuator, it is difficult to reduce the deflection angle Δθ per time when a wide field of view angle is to be set, and thus there is a problem that a desired resolution cannot be obtained.

[0012] The present invention is completed to solve the above problems, and its object is to obtain the following optical scanning device: compared with the case where light is scanned only by rotating a mirror around two axes by an actuator, the resolution of optical scanning can be improved.

[0013] Means for solving the problem

[0014] The optical scanning device of the present invention includes: a light source capable of changing the wavelength or phase of the output light; an optical mode converter connected to an optical waveguide that propagates the light output from the light source, and continuously changes the emission direction of the light propagating in the optical waveguide along with the continuous change of the wavelength of the light output from the light source or the phase of the light output from the light source; a mirror disposed on the outer periphery of the optical mode converter, reflecting the light reflected by the ranging object after being emitted from the optical mode converter toward a light receiver; and an actuator that rotates the optical mode converter and the mirror around two perpendicular axes respectively.

[0015] Effect of the invention

[0016] According to the present invention, compared with the case where light is scanned only by rotating a mirror around two axes by an actuator, the resolution of optical scanning can be improved. Description of the drawings

[0017] Figure 1 It is a structural diagram showing the optical scanning device 2 of Embodiment 1.

[0018] Figure 2 It is a structural diagram showing a ranging device having the optical scanning device 2 of Embodiment 1.

[0019] Figure 3 It is a hardware structural diagram of a computer when the distance calculation unit 11 is implemented by software or firmware, etc.

[0020] Figure 4 It is an explanatory diagram showing an example of the scanning trajectory of light.

[0021] Figure 5 It is an explanatory diagram showing the structure of the optical mode converter 5.

[0022] Figure 6 It is a structural diagram showing another ranging device having the optical scanning device 2 of Embodiment 1.

[0023] Figure 7 It is a structural diagram showing the optical scanning device 2 of Embodiment 2.

[0024] Figure 8 It is an explanatory diagram showing an example of the scanning trajectory of light.

[0025] Figure 9 It is a structural diagram showing the optical scanning device 2 of Embodiment 3.

[0026] Figure 10 This is a structural diagram showing the distance measuring device of the optical scanning device 2 with Embodiment 3.

[0027] Figure 11 This is a structural diagram showing the optical scanning device 2 of Embodiment 4.

[0028] Figure 12 This is a structural diagram showing the optical scanning device 2 of Embodiment 5.

[0029] Figure 13 This is an explanatory diagram showing an example of the scanning trajectory of light. Detailed Embodiments

[0030] Hereinafter, in order to explain the present invention in more detail, the embodiments for implementing the present invention will be described with reference to the drawings.

[0031] Embodiment 1

[0032] Figure 1 This is a structural diagram showing the optical scanning device 2 of Embodiment 1.

[0033] Figure 2 This is a structural diagram showing the distance measuring device of the optical scanning device 2 with Embodiment 1.

[0034] The light source 1 is an oscillator that outputs light to the optical scanning device 2.

[0035] The light source 1 can change the wavelength or the phase of the light output to the optical scanning device 2.

[0036] In addition, the light source 1 outputs a signal indicating the timing of outputting light to the optical scanning device 2 (hereinafter referred to as "the first timing signal") to the distance calculation unit 11.

[0037] In Figure 2 In the distance measuring device shown, the light source 1 provided outside the optical scanning device 2 is directly connected to the optical scanning device 2. However, this is merely an example, and the light source 1 may also be connected to the optical scanning device 2 via an optical fiber or the like.

[0038] In addition, the optical scanning device 2 may also have the light source 1.

[0039] The optical scanning device 2 is disposed in a three-dimensional space represented by an x - y - z coordinate system.

[0040] The optical scanning device 2 includes an optical input port 3, an optical waveguide 4, an optical mode converter 5, a mirror 6, and an actuator 7.

[0041] The optical scanning device 2 is a device for reflecting the light reflected by the ranging object 8 after emitting the light output from the light source 1 toward the ranging object 8.

[0042] The optical input port 3 is connected to one end of the optical waveguide 4.

[0043] The optical input port 3 receives the light output from the light source 1.

[0044] The optical waveguide 4 has, for example, an optical path formed by a core and a cladding.

[0045] One end of the optical waveguide 4 is connected to the optical input port 3, and the other end of the optical waveguide 4 is connected to the optical mode converter 5.

[0046] The light received by the optical input port 3 propagates through the optical waveguide 4 to the optical mode converter 5.

[0047] The optical mode converter 5 is implemented, for example, by a grating coupler or an optical phased array.

[0048] The optical mode converter 5 changes the radiation direction of the light in accordance with a change in the wavelength of the light output from the light source 1 or a change in the phase of the light output from the light source 1.

[0049] As Figure 5 shown, the structure of the optical mode converter 5 is a structure that takes in the light propagating in the optical waveguide 4 like a box.

[0050] Figure 5 is an explanatory diagram showing the structure of the optical mode converter 5. In Figure 5 , the waveguide connection port 5a is an input port connected to the other end of the optical waveguide 4.

[0051] A grating coupler or an optical phased array is implemented on at least the inner surface of the light radiation surface 5b of the optical mode converter 5 among the inner surfaces of the box. The grating coupler and the optical phased array respectively correspond to a light transmissive diffraction grating.

[0052] The optical mode converter 5 radiates the light propagating in the optical waveguide 4 toward the ranging object 8.

[0053] Since a grating coupler or the like is implemented on the inner surface of the box, the radiation direction of the light radiated from the optical mode converter 5 is switched in accordance with a change in the wavelength of the light output from the light source 1. The direction in which the radiation direction is switched is a direction intersecting the direction in which the radiation direction is switched along with the rotation around the first axis 7d or a direction intersecting the direction in which the radiation direction is switched along with the rotation around the second axis 7e.

[0054] In Figure 5 the optical mode converter 5 shown, a grating coupler or the like is implemented on the inner surface of the light radiation surface 5b of the light. However, this is merely an example, and the optical mode converter 5 may also have a converter or the like that switches the radiation direction of the light when the wavelength of the light output from the light source 1 or the phase of the light output from the light source 1 changes.

[0055] The mirror 6 is a device for reflecting the light that is emitted from the optical mode converter 5 and reflected by the distance measurement object 8 back to the light receiver 10 described later.

[0056] As Figure 1 The mirror 6 included in the optical scanning device 2 shown can be any mirror. For example, it can be a metal mirror or a glass mirror.

[0057] The actuator 7 has a first planar portion 7a that holds the optical waveguide 4, the optical mode converter 5, and the mirror 6; a second planar portion 7b that holds the optical waveguide 4; a third planar portion 7c that holds the optical input port 3; a first axis 7d; and a second axis 7e.

[0058] In the figure, the first planar portion 7a, the second planar portion 7b, and the third planar portion 7c are respectively arranged parallel to the x - y plane.

[0059] The planar shape of the first planar portion 7a is circular.

[0060] The planar shape of the second planar portion 7b is annular, and the first planar portion 7a is arranged inside the annulus.

[0061] The first planar portion 7a and the second planar portion 7b are connected via the second axis 7e.

[0062] The planar shape of the third planar portion 7c is rectangular, and a circular hole is provided inside. The second planar portion 7b is arranged inside the third planar portion 7c.

[0063] The second planar portion 7b and the third planar portion 7c are connected via the first axis 7d.

[0064] The first axis 7d is a rotation axis in the direction parallel to the x - axis and is the rotation axis of the actuator 7.

[0065] The second axis 7e is a rotation axis of the actuator 7 perpendicular to the first axis 7d and is a rotation axis in the direction parallel to the y - axis.

[0066] In Figure 1 In the optical scanning device 2 shown, the first axis 7d and the second axis 7e are perpendicular. However, the first axis 7d and the second axis 7e are not limited to being strictly perpendicular and can deviate from the perpendicular within a range where there is no practical problem. The "perpendicular" in this specification is a concept that includes the case of deviating from the perpendicular within a range where there is no practical problem.

[0067] The actuator 7 rotates the optical mode converter 5 and the mirror 6 respectively around the first axis 7d and rotates the optical mode converter 5 and the mirror 6 respectively around the second axis 7e according to the control signal output from the control circuit 12 described later.

[0068] The principles of rotation about the first axis 7d and rotation about the second axis 7e in the actuator 7 are each well known (see, for example, Patent Document 1).

[0069] In Figure 1 In the optical scanning device 2 shown, the planar shape of the first planar portion 7a is circular. However, this is merely an example. For example, the planar shape of the first planar portion 7a may also be rectangular. When the planar shape of the first planar portion 7a is rectangular, the planar shape of the second planar portion 7b is a rectangular ring shape, and the shape of the inner hole in the third planar portion 7c is rectangular.

[0070] The distance measurement target object 8 is an object to be Figure 2 measured by the distance measurement device shown.

[0071] The distance measurement target object 8 is provided in the same three-dimensional space as the optical scanning device 2.

[0072] In Figure 2 In order to simplify the drawings, the shape of the distance measurement target object 8 is depicted as a planar shape. However, in reality, the shape of the distance measurement target object 8 is three-dimensional, and the surface of the distance measurement target object 8 that faces the optical scanning device 2 is optically scanned by the optical scanning device 2.

[0073] In Figure 2 In the distance measurement device shown, for simplicity of explanation, the same coordinate system is used to represent the three-dimensional space in which the optical scanning device 2 is provided and the three-dimensional space in which the distance measurement target object 8 is provided. When representing the coordinate system of the three-dimensional space in which the optical scanning device 2 is provided (hereinafter referred to as the "first coordinate system") and the coordinate system of the three-dimensional space in which the distance measurement target object 8 is provided (hereinafter referred to as the "second coordinate system") separately, the x-axis direction in the first coordinate system and the x-axis direction in the second coordinate system do not necessarily become the same direction. In addition, the y-axis direction in the first coordinate system and the y-axis direction in the second coordinate system do not necessarily become the same direction.

[0074] The lens 9 is an optical element for converging the light reflected by the mirror 6 onto the light receiver 10.

[0075] The light receiver 10 receives the light converged by the lens 9.

[0076] In addition, the light receiver 10 outputs a signal indicating the timing of the received light (hereinafter referred to as the "second timing signal") to the distance calculation unit 11.

[0077] Alternatively, by disposing the light receiver 10 near the mirror, the light receiver 10 directly receives the reflected light without passing through the mirror. In this case, the mirror is not required.

[0078] The distance calculation unit 11 is implemented by, for example, a distance calculation circuit.

[0079] The distance calculation unit 11 includes a time measurement unit 11a and a distance calculation processing unit 11b.

[0080] The distance calculation unit 11 calculates the distance from the optical scanning device 2 to the distance measurement object 8 based on the time from receiving the first timing from the light source 1 to receiving the second timing from the light receiver 10.

[0081] The time measurement unit 11a measures the time from when the light is emitted from the optical mode converter 5 until the reflected light is received by the light receiver 10. That is, the time measurement unit 11a measures the time from receiving the first timing from the light source 1 to receiving the second timing from the light receiver 10.

[0082] The distance calculation processing unit 11b calculates the distance from the optical scanning device 2 to the distance measurement object 8 based on the time measured by the time measurement unit 11a.

[0083] The control circuit 12 is provided outside the optical scanning device 2.

[0084] The control circuit 12 controls the rotational movement of the actuator 7 about the first axis 7d and the rotational movement about the second axis 7e respectively.

[0085] In Figure 1 it is assumed that the distance calculation unit 11, which is a structural element of the distance measurement device, is implemented by a distance calculation circuit as dedicated hardware.

[0086] The distance calculation circuit is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a component obtained by combining them.

[0087] The distance calculation unit 11 is not limited to being implemented by dedicated hardware, and the distance calculation unit 11 can also be implemented by software, firmware, or a combination of software and firmware.

[0088] The software or firmware is stored as a program in the memory of a computer. A computer means the hardware that executes the program, such as a CPU (Central Processing Unit), a central processing device, a processing device, an arithmetic device, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor).

[0089] Figure 3 It is a hardware structure diagram of a computer in the case where the distance calculation unit 11 is implemented by software or firmware, etc.

[0090] When the distance calculation unit 11 is implemented by software, firmware, or the like, a program for causing a computer to execute the processing steps of the distance calculation unit 11 is stored in the memory 21. Further, the processor 22 of the computer executes the program stored in the memory 21.

[0091] Next, Figure 2 the operation of the distance measuring device shown

[0092] The light source 1 outputs light to the light input port 3 of the optical scanning device 2.

[0093] In addition, the light source 1 outputs a first timing signal indicating the timing at which the light is output to the distance calculation unit 11.

[0094] The light input port 3 receives the light output from the light source 1. The light received by the light input port 3 propagates through the optical waveguide 4 to the optical mode converter 5.

[0095] The optical mode converter 5 radiates the light that has propagated through the optical waveguide 4 toward the distance measurement object 8.

[0096] The light radiated from the optical mode converter 5 is reflected by the distance measurement object 8.

[0097] The mirror 6 reflects the light that has been radiated from the optical mode converter 5 and reflected by the distance measurement object 8 toward the light receiver 10.

[0098] The lens 9 converges the light reflected by the mirror 6 onto the light receiver 10.

[0099] The light receiver 10 receives the light converged by the lens 9 and outputs a second timing signal indicating the timing at which the light is received to the distance calculation unit 11.

[0100] The distance calculation unit 11 calculates the time T from when the light is output until it is received based on the time t s at which the first timing signal is received from the light source 1 and the time t r at which the second timing signal is received from the light receiver 10, as shown in the following equation (1).

[0101] T = t r - t s (1)

[0102] Next, the distance calculation unit 11 calculates the distance L from the optical scanning device 2 to the position on the distance measurement object 8 where the light is irradiated using the calculated time T, as shown in the following equation (2).

[0103]

[0104] In equation (2), c is the speed of light.

[0105] The actuator 7 rotates the optical mode converter 5 and the mirror 6 about the first axis 7d respectively, so that the distances L to multiple positions on the surface of the ranging object 8 can be calculated. In addition, the actuator 7 rotates the optical mode converter 5 and the mirror 6 about the second axis 7e respectively.

[0106] The actuator 7 rotates the optical mode converter 5 and the mirror 6 respectively, whereby, as Figure 4 shown by the solid line, the light can be scanned.

[0107] Figure 4 is an explanatory diagram showing an example of the scanning trajectory of the light.

[0108] When light is output from the light source 1, when the actuator 7 rotates the optical mode converter 5 and the mirror 6 respectively as described below, Figure 4 the scanning trajectory of the light shown appears.

[0109] First, the actuator 7 changes the rotation angle θx about the first axis 7d from θx1 to θx2, whereby the position of the light irradiated on the surface of the ranging object 8 is moved in a direction parallel to the y-axis (hereinafter referred to as "the first rotation operation"). In addition, the distance calculation unit 11 calculates the distance L at multiple positions during the first rotation operation.

[0110] Next, the actuator 7 changes the rotation angle θy about the second axis 7e by Δθ, whereby the position of the light irradiated on the surface of the ranging object 8 in the x-axis direction is changed (hereinafter referred to as "the second rotation operation"). In addition, the distance calculation unit 11 calculates the distance L at multiple positions during the second rotation operation. Hereinafter, the set of the first rotation operation and the second rotation operation is referred to as the first light scan.

[0111] In Figure 4 the example, the actuator 7 changes the rotation angle θy about the second axis 7e when the first rotation operation is about to end, so that the scanning trajectory of the light depicts a curve. When the actuator 7 changes the rotation angle θy about the second axis 7e after the first rotation operation ends, the position of the light irradiated on the surface of the ranging object 8 changes in a direction parallel to the x-axis.

[0112] Next, the actuator 7 changes the rotation angle θx about the first axis 7d from θx2 to θx1, whereby the position of the light irradiated on the surface of the ranging object 8 is moved in a direction parallel to the y-axis (hereinafter referred to as "the third rotation operation"). In addition, the distance calculation unit 11 calculates the distance L at multiple positions during the third rotation operation.

[0113] Next, the actuator 7 changes the rotation angle θy about the second axis 7e by Δθ, thereby changing the position of the light in the x-axis direction that is irradiated onto the surface of the distance measurement object 8 (hereinafter referred to as "the fourth rotation operation"). In addition, the distance calculation unit 11 calculates the distance L at a plurality of positions during the fourth rotation operation. Hereinafter, the group of the third rotation operation and the fourth rotation operation is referred to as the second light scan.

[0114] In Figure 4 the example, the actuator 7 changes the rotation angle θy about the second axis 7e at the end of the third rotation operation, so the scanning trajectory of the light depicts a curve. When the actuator 7 changes the rotation angle θy about the second axis 7e after the third rotation operation, the position of the light irradiated onto the surface of the distance measurement object 8 changes in a direction parallel to the x-axis.

[0115] The actuator 7 alternately repeats the first light scan and the second light scan, thereby achieving Figure 4 the light scan shown by the solid line in. The actuator 7 may also perform both the first light scan and the second light scan simultaneously.

[0116] The light source 1 can change the wavelength or the phase of the light output to the light scanning device 2.

[0117] In Figure 2 the shown distance measurement device, the light source 1 itself changes the wavelength or the phase of the light. However, this is merely an example, and the light source 1 may also change the wavelength or the phase of the light according to the control signal output from the control circuit 12.

[0118] The light source 1 changes the wavelength or the phase of the light output to the light scanning device 2, whereby the emission direction of the light emitted from the optical mode converter 5 changes.

[0119] The direction in which the emission direction is switched is a direction intersecting with the direction in which the emission direction is switched along with the rotation about the first axis 7d, or a direction intersecting with the direction in which the emission direction is switched along with the rotation about the second axis 7e.

[0120] Figure 4 The dotted line shown in represents the light scanning trajectory that appears due to the change in the emission direction of the light emitted from the optical mode converter 5. In Figure 4 the example, it is shown that the direction in which the emission direction is switched is a direction intersecting with the direction in which the emission direction is switched along with the rotation about the first axis 7d.

[0121] In Figure 2 it is shown that the direction in which the emission direction is switched is both a direction intersecting with the direction in which the emission direction is switched along with the rotation about the first axis 7d and a direction intersecting with the direction in which the emission direction is switched along with the rotation about the second axis 7e.

[0122] For example, through the scanning trajectory of light shown by the dashed line that appears Figure 4 , the resolution of the light scanning in the direction parallel to the x-axis in the light scanning device 2 is improved.

[0123] In the above Embodiment 1, the light scanning device 2 is configured to include: an optical mode converter 5 that changes the emission direction of light in accordance with a change in the wavelength of the light output from the light source 1 or the phase of the light output from the light source 1; and an actuator 7 that rotates the optical mode converter 5 around two perpendicular axes respectively. Therefore, in the light scanning device 2, compared with the case where light is scanned only by rotating a mirror around two axes by the actuator, the resolution of the light scanning can be improved.

[0124] In Figure 1 In the shown light scanning device 2, the rotation axis in the direction parallel to the x-axis is the first axis 7d, and the rotation axis in the direction parallel to the y-axis is the second axis 7e. However, this is merely an example, and it may also be that the rotation axis in the direction parallel to the x-axis is the second axis 7e, and the rotation axis in the direction parallel to the y-axis is the first axis 7d.

[0125] Figure 2 The shown distance measuring device has one light receiver 10. However, this is merely an example. For example, in the case where the reflection direction of the light based on the mirror 6 changes significantly, as Figure 6 shown, a plurality of light receivers 10 may also be arrayed one-dimensionally along the reflection direction of the light.

[0126] Figure 6 is a structural diagram showing another distance measuring device having the light scanning device 2 of Embodiment 1.

[0127] Embodiment 2

[0128] In Embodiment 2, a light scanning device 2 is described as follows: The optical waveguide 4' is branched into a plurality of branches, and optical mode converters 5-1, 5-2, and 5-3 are respectively connected to the plurality of branch destinations 4a, 4b, and 4c of the optical waveguide 4'.

[0129] Figure 7 is a structural diagram showing the light scanning device 2 of Embodiment 2. In Figure 7 In, the same reference numerals as Figure 1 denote the same or corresponding parts, and thus the description thereof is omitted.

[0130] The optical waveguide 4' has, for example, an optical path formed by a core and a cladding.

[0131] One end of the optical waveguide 4' is connected to the light input port 3, and the other end of the optical waveguide 4' is branched into a plurality of branches.

[0132] InFigure 7 In the optical scanning device 2 shown, the other end of the optical waveguide 4' is branched into three. However, this is merely an example, and the other end of the optical waveguide 4' may also be branched into two or more than four.

[0133] Optical mode converters 5-1, 5-2, and 5-3 are respectively connected to the three branching destinations 4a, 4b, and 4c at the other end of the optical waveguide 4'.

[0134] The optical mode converters 5-1, 5-2, and 5-3 are respectively the same optical mode converters as the Figure 2 optical mode converter 5 shown.

[0135] In Figure 7 the optical scanning device 2 shown, the optical mode converters 5-1, 5-2, and 5-3 are respectively arranged at mutually different positions with respect to the first planar portion 7a and arranged in mutually different orientations. Therefore, even if both the wavelength and phase of the light output from the light source 1 to the optical mode converters 5-1, 5-2, and 5-3 are the same, the directions of the light emitted from the optical mode converters 5-1, 5-2, and 5-3 are different. Therefore, the light emitted from the optical mode converters 5-1, 5-2, and 5-3 irradiates mutually different positions on the distance measurement object 8. The wavelengths or the phases of the light output from the light source 1 to the optical mode converters 5-1, 5-2, and 5-3 may be mutually different, and in this case, the light emitted from the optical mode converters 5-1, 5-2, and 5-3 also irradiates mutually different positions on the distance measurement object 8.

[0136] In the case where the optical mode converters 5-1, 5-2, and 5-3 are respectively arranged in mutually different orientations, as Figure 6 shown, a plurality of light receivers 10 may also be used. Each light receiver 10 is arranged at a position for receiving the light reflected by the distance measurement object 8 after being emitted from each of the optical mode converters 5-1, 5-2, and 5-3.

[0137] The first planar portion 7a in the actuator 7 holds the optical mode converters 5-1, 5-2, and 5-3 and the mirror 6.

[0138] The actuator 7 rotates the optical mode converters 5-1, 5-2, and 5-3 and the mirror 6 respectively around the first axis 7d and rotates the optical mode converters 5-1, 5-2, and 5-3 and the mirror 6 respectively around the second axis 7e.

[0139] Figure 8 is an explanatory diagram showing an example of the scanning trajectory of light.

[0140] Similar to the first embodiment, the actuator 7 alternately repeats the first light scan and the second light scan, and thereby scans the light as shown by the solid line in Figure 8 .

[0141] The light source 1 changes the wavelength or the phase of the light output to the light scanning device 2, whereby the emission directions of the light emitted from the optical mode converters 5-1, 5-2, and 5-3 change respectively.

[0142] The emission directions of the light emitted from the optical mode converters 5-1, 5-2, and 5-3 change respectively, whereby Figure 8 the scanning trajectory of such light as shown by the dashed line appears. By Figure 8 the scanning trajectory of such light as shown by the dashed line appearing, the resolution of the light scanning in the direction parallel to the x-axis in the light scanning device 2 is improved.

[0143] In the above Embodiment 2, Figure 7 the light scanning device 2 shown is configured such that the optical waveguide 4' is branched into a plurality of branches, and the optical mode converters 5-1, 5-2, and 5-3 are respectively connected to the plurality of branch destinations 4a, 4b, and 4c of the optical waveguide 4'. The actuator 7 rotates the optical mode converters 5-1, 5-2, and 5-3 and the mirror 6 respectively about the first axis 7d and rotates the optical mode converters 5-1, 5-2, and 5-3 and the mirror 6 respectively about the second axis 7e. Therefore, in Figure 7 the light scanning device 2 shown, compared with the case where light is scanned only by rotating a mirror about two axes by an actuator, the resolution of the light scanning can be improved. In addition, Figure 7 the light scanning device 2 shown and Figure 2 the light scanning device 2 shown, even if the operation of rotating about the second axis 7e in the actuator 7 is reduced, the entire surface of the surface of the ranging object 8 facing the light scanning device 2 can be scanned with light.

[0144] Embodiment 3

[0145] In Embodiment 3, a light scanning device 2 having a plurality of optical waveguides 4-1, 4-2, 4-3 and a plurality of optical mode converters 5-1, 5-2, 5-3 will be described.

[0146] Figure 9 is a structural diagram showing the light scanning device 2 of Embodiment 3. In Figure 9 it, the same reference numerals as Figure 1 and Figure 7 denote the same or corresponding parts, and thus the description thereof is omitted.

[0147] The optical waveguides 4-1, 4-2, 4-3 have, for example, an optical path formed by a core and a cladding.

[0148] One end of each of the optical waveguides 4-1, 4-2, 4-3 is connected to one light source 1 via the light input port 3.

[0149] The other end of the optical waveguide 4-1 is connected to the optical mode converter 5-1, and the other end of the optical waveguide 4-2 is connected to the optical mode converter 5-2. In addition, the other end of the optical waveguide 4-3 is connected to the optical mode converter 5-3.

[0150] The optical mode converters 5-1, 5-2, and 5-3 can be configured to have the same orientation or different orientations from each other.

[0151] Figure 9 The illustrated optical scanning device 2 includes the optical waveguides 4-1, 4-2, 4-3 and the optical mode converters 5-1, 5-2, 5-3. However, this is merely an example. Figure 9 The number of the optical waveguides 4 included in the illustrated optical scanning device 2 and the number of the optical mode converters 5 included in the optical scanning device 2 may each be two or four or more, respectively.

[0152] When the optical scanning device 2 includes the optical waveguides 4-1, 4-2, 4-3 and the optical mode converters 5-1, 5-2, 5-3, the same effects as those of Figure 7 the illustrated optical scanning device 2 are obtained.

[0153] Figure 10 FIG. is a structural diagram of a distance measuring device including the optical scanning device 2 according to Embodiment 3. In Figure 10 this, Figure 2 the same reference numerals denote the same or corresponding parts, and thus the description thereof is omitted.

[0154] Figure 10 The illustrated distance measuring device includes Figure 9 the illustrated optical scanning device 2.

[0155] The light sources 1-1, 1-2, and 1-3 are respectively the same light sources as Figure 2 the illustrated light source 1.

[0156] The light source 1-1 outputs light to the optical mode converter 5-1 via the optical waveguide 4-1, and the light source 1-2 outputs light to the optical mode converter 5-2 via the optical waveguide 4-2. In addition, the light source 1-3 outputs light to the optical mode converter 5-3 via the optical waveguide 4-3.

[0157] When each of the light sources 1-1, 1-2, and 1-3 outputs light, it notifies the distance calculation unit 11 of the fact that light has been output.

[0158] The light sources 1-1, 1-2, and 1-3 output light having different wavelengths or different phases from each other.

[0159] That is, the light source 1-1 outputs light with a wavelength of λ1 to the optical mode converter 5-1, the light source 1-2 outputs light with a wavelength of λ2 to the optical mode converter 5-2, and the light source 1-3 outputs light with a wavelength of λ3 to the optical mode converter 5-3.

[0160] In addition, the light source 1-1 varies the wavelength λ1 within a range of, for example, (λ1 - Δλ1) to (λ1 + Δλ1), the light source 1-2 varies the wavelength λ2 within a range of, for example, (λ2 - Δλ2) to (λ2 + Δλ2), and the light source 1-3 varies the wavelength λ3 within a range of, for example, (λ3 - Δλ3) to (λ3 + Δλ3).

[0161] Alternatively, the light source 1-1 outputs light with a phase of θ1 to the optical mode converter 5-1, the light source 1-2 outputs light with a phase of θ2 to the optical mode converter 5-2, and the light source 1-3 outputs light with a phase of θ3 to the optical mode converter 5-3.

[0162] In addition, the light source 1-1 varies the phase θ1 within a range of, for example, (θ1 - Δθ1) to (θ1 + Δθ1), the light source 1-2 varies the phase θ2 within a range of, for example, (θ2 - Δθ2) to (θ2 + Δθ2), and the light source 1-3 varies the phase θ3 within a range of, for example, (θ3 - Δθ3) to (θ3 + Δθ3).

[0163] The time measurement unit 11a of the distance calculation unit 11 measures the time from when the light is emitted from the optical mode converters 5-1, 5-2, and 5-3 until the reflected light is received by the optical mode converters 5-1, 5-2, and 5-3, respectively.

[0164] The distance calculation processing unit 11b calculates the distance from the optical scanning device 2 to the distance measurement object 8 based on each of the times measured by the time measurement unit 11a.

[0165] In the above-described Embodiment 3, the distance measurement device is configured to include a plurality of light sources 1-1, 1-2, and 1-3, and the light sources 1-1, 1-2, and 1-3 output light with mutually different wavelengths or light with mutually different phases. Therefore, it is possible to set the switching directions of the emission directions of the light emitted from the optical mode converters 5-1, 5-2, and 5-3 to different switching directions.

[0166] In Figure 10 In the shown distance measurement device, the light sources 1-1, 1-2, and 1-3 output light with mutually different wavelengths or light with mutually different phases.

[0167] Embodiment 4

[0168] In Embodiment 4, an optical scanning device 2 having an optical demultiplexer 13 that demultiplexes the light propagating in the optical waveguide 4 according to wavelength will be described.

[0169] Figure 11 is a structural diagram showing the optical scanning device 2 of Embodiment 4. In Figure 11 , the same reference numerals as Figure 1 and Figure 7 represent the same or corresponding parts, and thus the description thereof is omitted.

[0170] An optical demultiplexer 13 is inserted in the middle of the optical waveguide 4.

[0171] The optical demultiplexer 13 demultiplexes the light propagating in the optical waveguide 4 according to wavelength.

[0172] When light containing multiple wavelengths λ1, λ2, and λ3 is output from the light source 1, the optical demultiplexer 13 demultiplexes the light propagating in the optical waveguide 4 according to wavelength. For example, the optical demultiplexer 13 outputs the light of wavelength λ1 to the optical mode converter 5-1, the light of wavelength λ2 to the optical mode converter 5-2, and the light of wavelength λ3 to the optical mode converter 5-3.

[0173] In the above Embodiment 4, Figure 11 the optical scanning device 2 shown is configured to include: an optical demultiplexer 13 that is inserted in the middle of the optical waveguide 4 and demultiplexes the light propagating in the optical waveguide 4 according to wavelength; and a plurality of optical mode converters 5-1, 5-2, and 5-3 as the optical mode converter 5 that radiate each of the multiple lights after demultiplexing by the optical demultiplexer 13 toward the distance measurement object 8. Therefore, in Figure 11 the optical scanning device 2 shown, compared with scanning the light only by rotating the mirror around two axes by the actuator, the resolution of the optical scanning can be improved. In addition, Figure 11 the optical scanning device 2 shown compared with Figure 2 the optical scanning device 2 shown, even if the rotation operation of the actuator 7 around the second axis 7e is reduced, the entire surface of the surface of the distance measurement object 8 facing the optical scanning device 2 can be optically scanned. Furthermore, the switching directions of the radiation directions of the lights radiated from the optical mode converters 5-1, 5-2, and 5-3 can be set to different switching directions.

[0174] Embodiment 5

[0175] In Embodiment 5, an optical scanning device 2 is described as follows: Instead of mounting the mirror 6, the optical mode converter 5' receives the light reflected by the distance measurement object 8 and outputs the received light to the optical waveguide 4.

[0176] Figure 12 is a structural diagram showing the optical scanning device 2 of Embodiment 5. In Figure 12 , the same reference numerals as Figure 1 represent the same or corresponding parts, and thus the description thereof is omitted.

[0177] The optical mode converter 5' is an optical mode converter having the same structure as the Figure 1 optical mode converter 5 shown, and radiates the light propagating in the optical waveguide 4 toward the ranging object 8.

[0178] The optical mode converter 5' is different from the Figure 1 optical mode converter 5 shown. After radiating light toward the ranging object 8, it receives the light reflected by the ranging object 8 and outputs the received light to the optical waveguide 4.

[0179] The optical circulator 14 is inserted into the optical waveguide 4.

[0180] The optical circulator 14 outputs the light output from the light source 1 to the optical mode converter 5' via the optical waveguide 4.

[0181] In addition, the optical circulator 14 outputs the light output from the optical mode converter 5' to the light receiver 10 via the optical output port 15 described later.

[0182] The optical output port 15 is connected to the light receiver 10 via an optical fiber, for example.

[0183] In the Figure 12 optical scanning device 2 shown, the optical mode converter 5' is connected to the light receiver 10 via the optical waveguide 4, the optical circulator 14, and the optical output port 15. Therefore, the ranging device does not need to have the lens 9.

[0184] In addition, the light received by the optical mode converter 5' propagates to the light receiver 10 via the optical waveguide 4, the optical circulator 14, and the optical output port 15.

[0185] In the ranging devices of Embodiments 1 to 5, the light source 1 or the light sources 1-1, 1-2, 1-3 always changes the wavelength of the light output to the optical mode converter 5 or the like, or changes the phase of the light output to the optical mode converter 5 or the like.

[0186] However, this is merely an example. The light source 1 or the light sources 1-1, 1-2, 1-3 may also temporarily change the wavelength of the light output to the optical mode converter 5 or the like, or change the phase of the light output to the optical mode converter 5 or the like.

[0187] Figure 13 It is an explanatory diagram showing an example of the scanning trajectory of light.

[0188] In the Figure 13In the example, when performing distance measurement on only two portions 16 of the surface of the distance measurement object 8 facing the optical scanning device 2, the light source 1 or light sources 1-1, 1-2, 1-3 change the wavelength of the light output to the optical mode converter 5 etc. or the phase of the light output to the optical mode converter 5 etc. When performing distance measurement on portions other than the two portions 16, the wavelength of the light output from the light source 1 or light sources 1-1, 1-2, 1-3 to the optical mode converter 5 etc. is constant, and in addition, the phase of the light output to the optical mode converter 5 etc. is constant.

[0189] When only a part of the portion 16 that requires detailed distance measurement on the surface of the distance measurement object 8, the light source 1 etc. temporarily change the wavelength etc. of the light output to the optical mode converter 5 etc., thereby not causing a reduction in the distance measurement accuracy of the portion 16, being able to reduce unnecessary distance measurement, and shortening the distance measurement time.

[0190] In addition, the present invention can perform free combinations of the respective embodiments, or deformations of any structural elements of the respective embodiments, or omissions of any structural elements in the respective embodiments.

[0191] Industrial Applicability

[0192] The present invention is applicable to an optical scanning device that emits light into space and then reflects the light reflected by the object to be distance-measured.

[0193] The present invention is applicable to a distance measurement device having an optical scanning device.

[0194] Reference Numeral Explanation

[0195] 1, 1-1, 1-2, 1-3: Light source; 2: Optical scanning device; 3: Optical input port; 4, 4’, 4-1, 4-2, 4-3: Optical waveguide; 4a, 4b, 4c: Branch destination; 5, 5’, 5-1, 5-2, 5-3: Optical mode converter; 5a: Waveguide connection port; 5b: Radiation surface; 6: Reflecting mirror; 7: Actuator; 7a: First planar portion; 7b: Second planar portion; 7c: Third planar portion; 7d: First axis; 7e: Second axis; 8: Distance measurement object; 9: Lens; 10: Light receiver; 11: Distance calculation unit; 11a: Time measurement unit; 11b: Distance calculation processing unit; 12: Control circuit; 13: Optical demultiplexer; 14: Optical circulator; 15: Optical output port; 16: Portion; 21: Memory; 22: Processor.

Claims

1. An optical scanning device, comprising: a light source capable of changing the wavelength or phase of the output light; an optical mode converter connected to an optical waveguide that propagates the light output from the light source and radiates the light received through the optical waveguide; a mirror disposed on the outer periphery of the optical mode converter to reflect the light reflected by the ranging object after being radiated from the optical mode converter toward a light receiver; and an actuator having a first planar portion, a second planar portion, and a third planar portion, wherein the second planar portion has a hole for setting the first planar portion, and the third planar portion has a hole for setting the second planar portion, the third planar portion supports the second planar portion through a first axis, and is connected to the second planar portion through the first axis and can rotate about the first axis, the second planar portion supports the first planar portion through a second axis perpendicular to the first axis, and is connected to the first planar portion through the second axis and can rotate about the second axis, the first planar portion holds the optical mode converter and the mirror, the optical mode converter changes the radiation direction of the light output from the optical mode converter in accordance with a change in the wavelength or phase of the light output from the light source, the actuator rotates the first planar portion about each of the first axis and the second axis.

2. The optical scanning device according to claim 1, characterized in that in accordance with a change in the wavelength or phase of the light output from the light source, the radiation direction of the light from the optical mode converter rotates about the first axis, the first axis is any one of the two rotation axes of the actuator.

3. The optical scanning device according to claim 1, characterized in that a plurality of the optical mode converters are used, each optical mode converter is formed in a box shape, is disposed at mutually different positions with respect to a plane serving as a reference of the actuator, and the light radiation surfaces are disposed at mutually different orientations with respect to this plane.

4. The optical scanning device according to claim 1, characterized in that a plurality of the optical mode converters are used, lights having mutually different wavelengths or mutually different phases are output from the light source to each optical mode converter.

5. The optical scanning device according to claim 1, characterized in that the optical mode converter receives the following reflected light, which is the light that propagates in the optical waveguide from the light source, is radiated from the radiation surface of the optical mode converter, and is reflected by the ranging object.

6. A ranging device, characterized in that, The ranging device comprises: the optical scanning device according to claim 5; and a time measurement unit that measures the time from when the light is radiated from the optical mode converter until the optical mode converter receives the reflected light.

7. A ranging device, characterized in that, The ranging device comprises: the optical scanning device according to any one of claims 1 to 4; a light receiver that receives the reflected light, which is the light reflected by the ranging object after being radiated from the optical mode converter; and a time measurement unit that measures the time from when the light is radiated from the optical mode converter until the light receiver receives the reflected light.

8. The ranging device according to claim 7, characterized in that a plurality of the optical mode converters are used, each of the optical mode converters is formed in a box shape, is disposed at mutually different positions with respect to a plane serving as a reference for the actuator, and the light emission surfaces are disposed at mutually different orientations with respect to this plane, a plurality of the light receivers are used, each of the light receivers is disposed at a position where it receives light reflected by the ranging object after being emitted from each of the optical mode converters, that is, reflected light.

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