Light beam deflection device and light projecting and receiving device

Abstract

This light beam deflection device (100) comprises: a planar optical waveguide circuit (3) that causes light emitted from a light source (1) to branch into a first number of light that is the same as the number of divided areas in a first direction of a target space, and causes the branched light to be emitted from a predetermined emission position in the first direction such that the light is simultaneously emitted to the position of one pixel in the corresponding area; a first optical system (4) that converts the first number of light emitted from the planar optical waveguide circuit (3) into parallel light and emits the parallel light at an emission angle corresponding to a predetermined emission position; and a second optical system (5) that reflects the first number of light emitted from the first optical system (4) and irradiates the target space with the respective reflected light. The present invention makes it possible to provide a light beam deflection device which does not need to perform individual optical alignment for each of a plurality of observation visual fields.

Description

Light beam deflection device and light projecting / receiving device

[0001] The present invention relates to a light beam deflector that irradiates a target space with light and performs beam scanning in horizontal and vertical directions, and to a light projecting and receiving device that integrates a light beam deflector and a light receiving device.

[0002] LiDAR (Light Detection and Ranging) is a technology that uses laser light to measure the distance to an object and its shape based on the information from the reflected light. LiDAR requires deflection of the light beam irradiating the object to obtain a 3D image. Microelectromechanical systems (MEMS) mirrors are used as beam deflection devices for automotive LiDAR due to their compact size, low cost, and high reliability.

[0003] When applying MEMS mirrors to automotive LiDAR, (1) the optical deflection angle of the MEMS mirror is small compared to the required field of view, and (2) it is necessary to achieve both the required frame period and spatial resolution. Therefore, the observation field of view is divided into multiple fields of view, and measurements are taken simultaneously in the divided fields of view.

[0004] For example, Non-Patent Document 1 proposes a LiDAR device 1000 that divides the horizontal field of view into three parts using three transmitting laser diodes 101, as shown in FIG.

[0005] The LiDAR device 1000 shown in Non-Patent Document 1 employs a dTOF (direct Time of Flight) method in which pulsed light is emitted from a light source 101, the light reflected by an object 2000 is received by a sensor 107, and the distance to the object 2000 is measured by detecting the time of flight of the light from when it is emitted until it is received by the sensor 107.

[0006] The dTOF method can be realized with a relatively simple configuration, and has been increasingly integrated into single chips and modularized, leading to widespread practical use in automobiles, platform gates, industrial robots, etc. However, the dTOF method requires a filter to remove the effects of sunlight, etc., and cannot distinguish whether the received pulse is its own or that of another source, leading to the problem of interference with other LiDAR devices.

[0007] One proposed method for measuring the distance to an object is the frequency-modulated continuous wave (FMCW) method, which continuously emits laser light while changing its frequency and measures the frequency shift of the light returned from the object to measure the distance to the object. The FMCW method has limited practical application due to its complex configuration, but it is attracting attention as a high-precision LiDAR for autonomous driving because it is not affected by sunlight or other LiDARs and does not require a filter.

[0008] C.Niclass et al.,OPTICS EXPRESS 21 May 2012 Vol.20 ,No.11,11863

[0009] In the FMCW method, in addition to the round-trip propagation time of light, frequency-modulated light must be sent back and forth, which increases the measurement time.In addition, the observation field of view must be divided to cover the long measurement time, so multiple transmitter / receiver modules are required, and these multiple individual transmitter / receiver modules must be implemented with precision.

[0010] The conventional device described above is configured to implement multiple individual transmitter / receiver modules, and in order to accurately set the observation field of view covered by each transmitter / receiver module, it was necessary to perform optical alignment individually for each of the multiple observation fields.

[0011] The present invention has been made to solve the above-mentioned problems, and aims to provide a light beam deflector that can easily and accurately set an observation field of view without having to perform optical alignment individually for each of multiple observation fields.

[0012] In order to solve the above problem, the light beam deflection device of the present invention includes a light source; a planar optical waveguide circuit that branches light emitted from the light source into a first number of light beams equal to the number of divided areas in a first direction of a target space, and emits the branched light beams from predetermined emission positions in the first direction so that each of these light beams is simultaneously irradiated onto a pixel position in a corresponding area; a first optical system that converts each of the first number of light beams emitted from the planar optical waveguide circuit into parallel light beams and emits the parallel light beams at an emission angle corresponding to the predetermined emission position; and a second optical system that reflects each of the first number of light beams emitted from the first optical system and irradiates each reflected light beam onto the target space.

[0013] According to the present invention, it is possible to realize a light beam deflector that can easily and accurately set a plurality of observation fields without individually performing optical alignment for each of the observation fields.

[0014] FIG. 1 is a diagram illustrating the configuration of a light beam deflector according to a first embodiment of the present invention. FIG. 2A is a diagram illustrating the detailed configuration of the light beam deflector according to the first embodiment of the present invention. FIG. 2B is a diagram illustrating the detailed configuration of the light beam deflector according to the first embodiment of the present invention. FIG. 2C is a diagram illustrating the detailed configuration of the light beam deflector according to the first embodiment of the present invention. FIG. 3 is a diagram illustrating an observation field and beam scanning according to the first embodiment of the present invention. FIG. 4A is a diagram illustrating driving of a MEMS mirror according to the first embodiment of the present invention. FIG. 4B is a diagram illustrating driving of a MEMS mirror according to the first embodiment of the present invention. FIG. 5 is a diagram illustrating the configuration of a light projecting and receiving device according to a third embodiment of the present invention. FIG. 6 is a block diagram illustrating an example of the configuration of a computer of a control circuit that controls a MEMS mirror according to an embodiment of the present invention. FIG. 7 is a diagram illustrating the configuration of a conventional light beam deflector.

[0015] <Configuration of Light Beam Deflection Device> Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a diagram showing the configuration of a light beam deflection device according to a first embodiment of the present invention. In the following description, a case will be described in which the observation area of ​​the target space is divided in the horizontal direction (X-axis direction), but the observation area of ​​the target space may also be configured to be divided in the vertical direction (Y-axis direction). In this case, the direction in which the observation area is divided will sometimes be described as a first direction, and the direction perpendicular to the first direction will sometimes be described as a second direction.

[0016] The optical beam deflection device 100 includes a semiconductor laser 1, an optical amplifier 2 that amplifies the light emitted from the semiconductor laser 1, a planar optical waveguide circuit 3 that branches the light amplified by the optical amplifier 2 into a first number of light beams equal to the number of areas divided in the horizontal direction (first direction) of the target space and emits the branched light beams from predetermined emission positions in the horizontal direction so that each of the light beams is simultaneously irradiated onto a pixel position in a corresponding area, a focal plane lens 4 (first optical system) that converts each of the first number of light beams emitted from the planar optical waveguide circuit 3 into parallel light beams and emits each of the parallel light beams at an emission angle corresponding to the predetermined emission position, a MEMS mirror 5 (second optical system) that reflects each of the first number of light beams emitted from the focal plane lens 4 and irradiates the reflected light beams onto the target space, and a control circuit 6 that drives and controls the MEMS mirror 5 to control the deflection angle of the light reflected by the MEMS mirror 5. Reference numeral 2000 in FIG. 1 denotes a screen onto which light from the light beam deflector 100 is irradiated.

[0017] Laser light emitted from the semiconductor laser 1 is amplified by the optical amplifier 2 and then incident on the planar optical waveguide circuit 3. A semiconductor laser is suitable as the light source 1 when beam scanning is performed using a MEMS mirror as in this embodiment. The wavelength of the laser light emitted from the semiconductor laser 1 can be selected appropriately according to the mirror size of the MEMS mirror used, etc. The laser light is amplified in the optical amplifier 2 as needed. An EDFA (Erbium-Doped Fiber Amplifier) ​​can be used as the optical amplifier 2.

[0018] <Planar Optical Waveguide Circuit> The planar optical waveguide circuit 3 includes an optical waveguide 30 that guides the light amplified by the optical amplifier 2, a 1×16 optical splitter 31 that branches the light from the optical waveguide 30 into a first number (16) of light beams, and 16 optical waveguides 36 that guide each of the light beams branched by the optical splitter 31. The light beams branched by the optical splitter 31 are emitted from predetermined emission positions in the horizontal direction of the planar optical waveguide circuit 3.

[0019] <Focal Plane Lens> The focal plane lens 4 converts each of the first number of light beams output from the planar optical waveguide circuit 3 into parallel light beams, and outputs each of the parallel light beams at an output angle corresponding to a predetermined output position in the horizontal direction of the planar optical waveguide circuit 3, and deflects the light beams so that they pass through a focal point on the target space side of the focal plane lens 4. This makes it possible to make the first number of light beams output from the planar optical waveguide circuit 3 incident on the MEMS mirror with a beam size corresponding to the mirror size of the MEMS mirror.

[0020] <MEMS Mirror> The MEMS mirror 5 reflects each of the first number of light beams emitted from the focal plane lens 4 and irradiates the reflected light beams toward an observation area in the target space. The light beams emitted from the focal plane lens 4 are emitted at emission angles corresponding to predetermined emission positions in the horizontal direction of the planar optical waveguide circuit 3, and therefore the light beams reflected by the MEMS mirror 5 are also reflected at different angles. This makes it possible to simultaneously irradiate light onto a plurality of areas obtained by dividing the target space into the first number, and to simultaneously measure a plurality of observation areas obtained by dividing the observation field of view.

[0021] In this embodiment, the operation modes of the MEMS mirror are as follows: when driving the MEMS mirror in the horizontal direction (the X-axis direction in FIG. 1 ), the MEMS mirror is controlled by resonant drive control (non-linear mode) on a resonant drive axis capable of high-speed driving; and when driving the MEMS mirror in the vertical direction (the Y-axis direction in FIG. 1 ), the MEMS mirror is controlled by linear drive control (linear mode) on a linear drive axis capable of high-precision driving.

[0022] Fig. 2A is a configuration example of the optical beam deflector 100 of Fig. 1 as viewed from the Y-axis direction. As shown in Fig. 2A, the light branched by the planar optical waveguide circuit 3 is emitted from a predetermined emission position in the horizontal direction (X-axis direction) of the planar optical waveguide circuit 3, converted into parallel light by the focal plane lens 4, emitted at an emission angle corresponding to the predetermined emission position in the horizontal direction (X-axis direction) of the planar optical waveguide circuit 3, and deflected so as to pass through the focal point of the focal plane lens 4 on the target space side.

[0023] With this configuration, the light emitted by the focal plane lens 4 can be made incident on the MEMS mirror 5 with a beam size corresponding to the mirror size of the MEMS mirror 5. The light reflected by the MEMS mirror 5 is reflected at different angles corresponding to the angle of incidence on the MEMS mirror 5, and the light can be simultaneously irradiated onto the first number of divided areas of the target space.

[0024] The light split into the first number of beams is simultaneously deflected in each of the first number of areas by resonant driving in the horizontal direction (X-axis direction) of the MEMS mirror 5. This allows the light to be deflected so as to cover the range between the split beams in FIG. 2A.

[0025] Fig. 2B is a configuration example of the beam deflection device of Fig. 1 as viewed from the X-axis direction. As shown in Fig. 2B, light emitted from the planar optical waveguide circuit 3 is incident on the MEMS mirror 5 without changing its angle in the vertical direction (Y-axis direction) of the planar optical waveguide circuit 3, and is deflected by linear driving of the MEMS mirror 5 in the vertical direction (Y-axis direction), so that the light can be deflected so as to cover the vertical direction in the observation area.

[0026] 2C shows another example of the configuration of the beam deflector of FIG. 1 as viewed from the X-axis direction. As shown in FIG. 2C, a fixed mirror 7 and a relay lens 8 may be installed between the focal plane lens 4 and the MEMS mirror 5. This configuration is useful when the light incident on the MEMS mirror cannot be narrowed down to a beam size corresponding to the mirror size of the MEMS mirror due to restrictions on the distance between the focal plane lens 4 and the MEMS mirror 5 or the focal length of the focal plane lens 4.

[0027] <Target Specifications of In-Vehicle LiDAR> The target specifications of the in-vehicle LiDAR to which the present invention is applied will be described. Table 1 shows an example of the target specifications of the in-vehicle LiDAR.

[0028]

[0029] The specifications for automotive LiDAR require a horizontal resolution of 512 pixels, a vertical resolution of 128 pixels, and a frame rate of approximately 15 to 20 Hz. The time required to allocate to one pixel (the time required to process each pixel sequentially) is determined by the frame rate and spatial resolution. For example, if a total of 65,536 pixels, 512 pixels horizontally and 128 pixels vertically, are measured at a frame rate of 20 Hz (50 ms period), the time allocated to one pixel is 0.76 μs, as shown in Table 1.

[0030] As shown in Table 1, if the maximum distance measurement is 300 m, the round-trip time of light reflected from 300 m away and returning is 2 μs, which is longer than the 0.76 μs assigned to one pixel. Therefore, to achieve a frame rate of 20 Hz, it is necessary to divide the target space into areas and process each area simultaneously. In an actual device, device parameters such as the number of divided areas must be designed taking into account the round-trip propagation delay time of light as well as the time required for transmitting and receiving optical signals for measurement.

[0031] In this embodiment, the target space is divided into 16 observation areas for beam scanning. Table 2 shows an example of parameter design for the focal plane lens 4 and the planar optical waveguide circuit 3. Table 3 shows an example of specifications for the MEMS mirror 5.

[0032]

[0033]

[0034] The focal length of the focal plane lens is designed so that when the maximum distance measurement is 300 m, the beam diameter at a distance of 300 m satisfies a predetermined value and the beam diameter matches the mirror size of the MEMS mirror 5. When light with a wavelength of 1550 nm is used and a focal plane lens with a focal length of 12 mm is used, the beam diameter is 2.37 mm as shown in Table 2, which satisfies the MEMS mirror size (3.6 × 4.0 mm) in Table 3.

[0035] If the number of light branches in the planar optical waveguide circuit 3 is 16, and the horizontal viewing angle is 120°, the beam deflection angle due to the optical splitter and focal plane lens is 112.5°, and the array length required to obtain this beam deflection angle is 35.92 mm. In this case, the array spacing at the output end of the planar optical waveguide circuit 3 is 2394.57 μm, as shown in Table 2, which is a fully feasible array spacing.

[0036] 3 is a diagram illustrating the observation field and beam scanning according to the first embodiment of the present invention. In this embodiment, the observation area is divided into 16 areas in the horizontal direction, and high-speed resonant driving is performed simultaneously in each of the 16 divided areas, while linear driving capable of high-precision driving is performed in the vertical direction.

[0037] According to the specifications of the MEMS mirror 5 shown in Table 3, the drive in the horizontal direction (X-axis direction in FIG. 1) is performed by resonant drive with a drive frequency of 1100 Hz, and the drive in the vertical direction (Y-axis direction in FIG. 1) is performed by linear drive with a drive frequency of up to 100 Hz.

[0038] Table 4 shows an example of design of drive parameters for the MEMS mirror 5 when the MEMS mirror 5 of Table 3 is used.

[0039] When FMCW is used as the distance measurement method, if the FMCW up-chirp period and down-chirp period are each 5 μs and the maximum distance measurement distance is 300 m, the processing time per pixel is approximately 12 μs. When the horizontal drive frequency of the MEMS mirror is 1100 Hz, the horizontal scan time is approximately 454 μs, as shown in Table 4. The number of pixels that can be allocated to this 454 μs exceeds 32 pixels, and by setting the number of area divisions to 16, it is possible to meet the horizontal resolution target value of 512 pixels in Table 1.

[0040] 4A is a diagram for explaining the driving of the MEMS mirror according to the first embodiment of the present invention. When horizontal driving is repeated for the number of pixels in the vertical direction, the time required for horizontal beam scanning is 454×128≈58 ms.

[0041] Furthermore, as shown in Table 4, when the vertical drive frequency is 100 Hz, the time required for vertical beam scanning is 5 ms. In this case, the total time required for measuring the target space is the sum of the time required for horizontal beam scanning, which is 58 + 5 ≒ 63 ms, and the achievable frame rate is 15.83 Hz, as shown in Table 4. From the above, it can be seen that the target frame rate for automotive LiDAR shown in Table 1 can be met by using the design parameters listed in Tables 2 to 4.

[0042] 4B is a diagram for explaining the driving of the MEMS mirror according to the first embodiment of the present invention. In FIG. 4A, after the beam scanning in the vertical direction is completed, the beam scanning is performed by returning to the initial pixel position. As shown in FIG. 4B, after the beam scanning in the vertical direction is completed, the beam scanning may be performed in the opposite direction without returning to the initial pixel position in the vertical direction as in FIG. 4A. By performing the beam scanning as shown in FIG. 4B, the frame rate can be improved.

[0043] As described above, the optical system of the light beam deflector 100 according to the embodiment of the present invention is configured to include a planar optical waveguide circuit, a focal plane lens, and a MEMS mirror, split light emitted from a single light source, and irradiate each of the split light onto a plurality of divided observation areas, thereby enabling horizontal beam scanning in the plurality of observation areas simultaneously. This makes it possible to realize the light beam deflector 100, which does not require individual optical alignment in each of the plurality of observation areas. According to this embodiment, it has been confirmed that it is possible to realize the light beam deflector 100 that meets the target specifications of the automotive LiDAR to which the present invention is applied.

[0044] [Second embodiment] The 16 light beams emitted from the PLC (Planar Lightwave Circuit) splitter 31 and the focal plane lens 4 are incident on the MEMS mirror 5 with a spread of 112°. Therefore, the diameter of the MEMS mirror 5 as seen from the light beams incident obliquely on the surface of the MEMS mirror 5 is smaller than that of the light beams incident perpendicularly.

[0045] For example, the diameter (minor diameter) of the MEMS mirror as seen from a light beam incident obliquely at an angle θ from the vertical plane is cosθ, and if θ=60°, then cos=0.5, and the ratio of the minor diameter to the major diameter is 1:2.

[0046] For this reason, the MEMS mirror cannot receive the beam spread at the base of the Gaussian beam on the major axis side, and the transmitted optical power of an optical beam incident at an angle on the MEMS mirror 5 is lower than that of an optical beam incident perpendicularly.

[0047] To solve this problem, the decrease in transmission optical power at the periphery of the PLC splitter, which is far from the center, can be corrected by gradually changing the branching ratio of the optical power from the output ports (#8, #9) located at the center of the PLC splitter 31 toward the peripheral output ports (#1, #16). Specifically, by configuring the branching ratio of the optical energy in the splitter to increase at a predetermined rate with increasing distance from the central output position of the planar optical waveguide circuit 3, it is possible to correct the decrease in transmission optical power at the output ports located at the periphery of the PLC splitter.

[0048] The rate at which the branching ratio of the PLC splitter 31 is increased may be set according to the spread angle of the light beam emitted from the focal plane lens 4. When the spread angle is 112°, the branching ratio of the peripherally located output ports (#1, #16) may be increased by about 1 to 2 dB compared to the output ports (#8, #9) located at the center of the PLC splitter, and the branching ratio of the output ports between the center and the periphery (#2 to #7, #10 to #15) may be set to increase at a constant rate from the centrally located output ports (#8, #9).

[0049] In the first embodiment, the light beam deflector 100 applied to LiDAR is described. However, in LiDAR, it is necessary to receive light returning from the target space. In the third embodiment, the configuration of a light projecting and receiving device in which the light beam deflector 100 and a light receiving device are integrated will be described.

[0050] 5 shows an example of the configuration of a light projecting and receiving device that integrates an optical beam deflector 100 and a light receiving device. The light projecting and receiving device is configured by adding 16 photodetectors 9-1 to 9-16, 16 photodetectors 10-1 to 10-16, and 16 transimpedance amplifiers (TIAs) 11-1 to 11-16 to a planar optical waveguide circuit 3. The configuration from the focal plane lens 4 onwards is the same as that of the first embodiment, and is therefore omitted from FIG. 5.

[0051] The planar optical waveguide circuit 3 in the third embodiment includes an optical waveguide 30 (first optical waveguide), a 10:1 optical splitter 32 (first optical splitter) that splits light into two lights at a splitting ratio of 10:1, optical waveguides (33-1, 33-2) (second optical waveguide, third optical waveguide), 1×16 optical splitters (34-1, 34-2) (second optical splitter, third optical splitter) that split the light from the optical waveguides (33-1, 33-2) into 16 lights, respectively, and optical waveguides (36-1 to 36-16) (fourth optical waveguide) that guide the light output from the 1×16 optical splitter (34-1). The optical waveguide (36-17 to 36-32) (fifth optical waveguide) guides the light output from the 1x16 optical splitter (34-2), 3dB splitters (35-1 to 35-16) (fourth optical splitter) split the light reflected by an object present in the target space and incident on the optical waveguides (36-1 to 36-16) into two, and sixteen 3dB couplers (37-1 to 37-16) (first couplers) combine the light output from the 3dB splitters (35-1 to 35-16) and the light guided by the optical waveguides (36-17 to 36-32) in equal proportions, divide the light into two, and output the combined light.

[0052] The light (probe light) split by the 10:1 optical splitter 32 and then by the 1×16 optical splitter (34-1) is guided by the optical waveguides (36-1 to 36-16) and emitted from the output end of the planar optical waveguide circuit 3. The probe light emitted from the planar optical waveguide circuit 3 passes through the focal plane lens 4, is reflected by the MEMS mirror 5, and is emitted into the target space.

[0053] On the other hand, the light (reference light) split by the 10:1 optical splitter 32 and then split by the 1x16 optical splitter (34-2) is guided by the optical waveguides (36-17 to 36-32) and input to the input ports of the 3 dB couplers (37-1 to 37-16).

[0054] The return light reflected by an object present in the target space and returning from the target space travels the opposite path to the probe light, i.e., is reflected by the MEMS mirror 5, passes through the focal plane lens 4, and enters the exit end of the same optical waveguide (36-1 to 36-16) of the planar optical waveguide circuit 3 as the source of the probe light.

[0055] The return light is guided through the optical waveguides (36-1 to 36-16), split by the 3 dB splitters (35-1 to 35-16), and merged with the light (reference light) guided through the optical waveguides (36-17 to 36-32) at an equal ratio in the 3 dB couplers (37-1 to 37-16), split into two equal parts, and output from two ports.

[0056] The light output from the port (first port) of the 3 dB coupler (37-1 to 37-16) is guided by the optical waveguide (38-1 to 38-16), and the light output from the other port (second port) of the 3 dB coupler (37-1 to 37-16) is guided by the optical waveguide (39-1 to 39-16).

[0057] The photodetectors (9-1 to 9-16, 10-1 to 10-16) (first photodetector, second photodetector) convert the light guided in the optical waveguides (38-1 to 38-16) and the light guided in the optical waveguides (39-1 to 39-16) into electrical signals.

[0058] Transimpedance amplifiers (TIA) (11-1 to 11-16) obtain and amplify the difference between the output signals from the photodetectors (9-1 to 9-16, 10-1 to 10-16), thereby obtaining a received signal.

[0059] In the first embodiment, it is assumed that the light beam deflector 100 and the light receiving device are provided separately. On the other hand, in the third embodiment, the light beam deflector 100 and the light receiving device are integrated, but the total time required to measure the target space is the same as in the first embodiment, and the present embodiment can also satisfy the specifications of the automotive LiDAR shown in Table 1.

[0060] Note that the configuration after the TIAs (11-1 to 11-16) is not an essential component of the present invention, and is therefore omitted from Fig. 5. An example of the use of the received signals obtained by the TIAs (11-1 to 11-16) is LiDAR, but the application of the present invention is not limited to LiDAR.

[0061] The control circuit 6 described in the first embodiment is a control circuit that controls the drive current of the MEMS mirror 5. The control circuit 6 can be realized by a computer equipped with a CPU (Central Processing Unit), a storage device, and an interface, and a program that controls these hardware resources. An example configuration of this computer is shown in FIG. 6.

[0062] The computer includes a CPU 200, a storage device 201, and an interface device (I / F) 202. A circuit that supplies a control signal for driving the MEMS mirror and the like are connected to the I / F 202. In such a computer, a program for implementing the method of the present invention is stored in the storage device 201. The CPU 200 executes the processing described in the first embodiment in accordance with the program stored in the storage device 201.

[0063] (Scope of the present invention) The present invention is not limited to the above-described embodiment. The present invention includes various modifications to the above-described embodiment that can be understood by a person skilled in the art within the scope of the technical concept of the present invention. The configurations listed in the above-described embodiment can be combined as appropriate within a range that does not contradict each other.

[0064] (Additional Note) The configurations disclosed in this specification, taking the above-described embodiment as an example, will be exemplified below.

[0065] (Supplementary Note 1) A light beam deflection device comprising: a light source; a planar optical waveguide circuit that branches light emitted from the light source into a first number of light beams equal to the number of divided areas in a first direction of a target space, and emits the branched light beams from predetermined emission positions in the first direction so that each of the light beams is simultaneously irradiated onto a pixel position in a corresponding area; a first optical system that converts each of the first number of light beams emitted from the planar optical waveguide circuit into parallel light beams and emits the parallel light beams at an emission angle corresponding to the predetermined emission position; and a second optical system that reflects each of the first number of light beams emitted from the first optical system, and irradiates each reflected light beam onto the target space.

[0066] (Supplementary Note 2) The light beam deflection device according to Supplementary Note 1, further comprising a control circuit for controlling the deflection angle of the reflected light in the second optical system, wherein the control circuit is configured to perform drive control in the first direction to simultaneously deflect the first number of light beams irradiated from the second optical system to the target space in the first direction, and drive control in the second direction to simultaneously deflect the first number of light beams irradiated from the second optical system to the target space in the second direction by changing the deflection angle of the reflected light in a second direction perpendicular to the first direction.

[0067] (Supplementary Note 3) The optical beam deflector according to Supplementary Note 1 or 2, wherein the second optical system is a MEMS mirror, and the drive control in the first direction is resonant drive control on a resonant drive axis of the MEMS mirror, and the drive control in the second direction is linear drive control on a linear drive axis of the MEMS mirror. (Supplementary Note 4) The optical beam deflector according to any of Supplementary Notes 1 to 3, wherein the planar optical waveguide circuit includes a splitter that splits the light emitted from the light source into the first number of light beams, and the splitting ratio of the light energy in the splitter is set to increase at a predetermined rate with increasing distance from an output position at the center of the planar optical waveguide circuit.

[0068] (Supplementary Note 5) A planar optical waveguide circuit comprising: an optical beam deflector according to any one of Supplementary Notes 1 to 4; the first number of first photodetectors that convert incident light into an electric signal; the first number of second photodetectors that convert incident light into an electric signal; and the first number of transimpedance amplifiers that determine a difference between output signals of the first and second photodetectors, wherein the planar optical waveguide circuit comprises: a first optical waveguide; a first optical splitter that splits the light guided in the optical waveguide into two lights at a predetermined splitting ratio; a second optical waveguide and a third optical waveguide that guide the light output from the optical splitter; a second optical splitter that splits light from the first optical waveguide into a first number of lights, a third optical splitter that splits light from the second optical waveguide into the first number of lights, a first number of fourth optical waveguides that guide the light output from the second optical splitter, and a first number of fifth optical waveguides that guide the light output from the third optical splitter; the first number of fourth optical splitters that split into two each of the first number of return lights that are reflected by an object present in an object space and enter the fourth optical waveguide; and the first number of first couplers that combine the light output from the fourth optical splitter and the light guided in the fifth optical waveguide in equal proportions, divide the light in half, and output the combined light; the first optical detector converts the light output from a first port of the first coupler into an electrical signal; and the second optical detector converts the light output from a second port of the first coupler into an electrical signal. The light emitting and receiving device, wherein the transimpedance amplifier determines a difference between an output signal from the first photodetector and an output signal from the second photodetector.

[0069] The present invention can be applied to light deflection technology required for LiDAR and the like.

[0070] 1...semiconductor laser, 2...optical amplifier, 3...planar optical waveguide circuit, 4...focal plane lens, 5...MEMS mirror, 6...control circuit, 100...optical beam deflection device.

Claims

1. A light beam deflection device comprising: a light source; a planar optical waveguide circuit that branches light emitted from the light source into a first number of light beams equal to the number of divided areas in a first direction of a target space, and emits the branched light beams from predetermined emission positions in the first direction so that each of the light beams is simultaneously irradiated onto a pixel position in a corresponding area; a first optical system that converts each of the first number of light beams emitted from the planar optical waveguide circuit into parallel light beams and emits the parallel light beams at an emission angle corresponding to the predetermined emission positions; and a second optical system that reflects each of the first number of light beams emitted from the first optical system, and irradiates each reflected light beam onto the target space.

2. A light beam deflection device as described in claim 1, further comprising a control circuit for controlling the deflection angle of the reflected light in the second optical system, wherein the control circuit is configured to perform drive control in the first direction to simultaneously deflect the first number of light beams irradiated from the second optical system onto the target space in the first direction, and drive control in the second direction to simultaneously deflect the first number of light beams irradiated from the second optical system onto the target space in the second direction by changing the deflection angle of the reflected light in a second direction perpendicular to the first direction.

3. The optical beam deflector according to claim 2, wherein the second optical system is a MEMS mirror, the drive control in the first direction is resonant drive control on a resonant drive axis of the MEMS mirror, and the drive control in the second direction is linear drive control on a linear drive axis of the MEMS mirror.

4. An optical beam deflector according to claim 1, wherein the planar optical waveguide circuit comprises a splitter that splits the light emitted from the light source into the first number of light beams, and the splitting ratio of the light energy in the splitter is set to increase at a predetermined rate with increasing distance from the emission position at the center of the planar optical waveguide circuit.

5. An optical beam deflector according to claim 1, comprising: the first number of first photodetectors that convert incident light into an electrical signal; the first number of second photodetectors that convert incident light into an electrical signal; and the first number of transimpedance amplifiers that determine the difference between the output signals of the first and second photodetectors, wherein the planar optical waveguide circuit comprises: a first optical waveguide; a first optical splitter that splits the light guided in the optical waveguide into two beams at a predetermined splitting ratio; a second optical waveguide and a third optical waveguide that guide the light output by the optical splitter; a second optical splitter that splits the light from the first optical waveguide into the first number of beams; a third optical splitter that splits the light from the second optical waveguide into the first number of beams; a first number of fourth optical waveguides that guide the light output from the second optical splitter; and a first number of fifth optical waveguides that guide the light output from the third optical splitter. a first number of fourth optical splitters that split a first number of return lights that are reflected by an object present in a target space and enter the fourth optical waveguide into two, respectively; and a first number of first couplers that combine the light output from the fourth optical splitter and the light guided in the fifth optical waveguide in equal proportions, divide the light into two, and output the two equal beams; wherein the first photodetector converts the light output from a first port of the first coupler into an electrical signal; the second photodetector converts the light output from a second port of the first coupler into an electrical signal; and the transimpedance amplifier calculates a difference between the output signal from the first photodetector and the output signal from the second photodetector.

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