JP6828062B2 - Rider device - Google Patents

Description

The present invention generally relates to the fields of remote sensing and distance measurement, and in particular, lidar (LiDAR, Light Detection and Ranking) for performing three-dimensional spatial mapping, object detection, object tracking, and object identification in an autonomous driving system in real time. Regarding the device.

The lidar device sends the search light to the space, scans the space, receives the reflected return light generated by the search light reflected on the object in the space, and determines the direction and distance of the object in the space. Detect. An optical phased array (OPA, Optical Phased Array) is known as a device that constitutes such a rider device. A rider device using OPA can be configured to be faster and smaller than a rider device using a mechanical beam scanning device.

As an OPA that can be used in a rider device, conventionally, an OPA that is configured by arranging a plurality of unit cells each consisting of an optical coupler, a phase shifter, and an antenna element is known (Patent Document 1). ). However, in this OPA, since each unit cell is composed of many elements such as the above-mentioned optical coupler, the unit cell has an appropriate size. Therefore, there is a limit to reducing the arrangement interval of the unit cells, and therefore the arrangement interval of the antenna elements, and the angle range of the beam steering of the search light is narrowly limited due to the size of the arrangement interval.

Further, as another OPA that can be used in the lidar device, an OPA based on an optical integrated circuit (PIC) is conventionally known (Non-Patent Document 1). This OPA includes a bus waveguide for inputting light, a plurality of branch portions each composed of a thermal phase shifter and an evanescent coupler, and a plurality of branch portions provided on the bus waveguide, and the evanescent coupler. It is composed of a plurality of grating-based antenna elements that transmit each of the plurality of lights branched by each to the space. In this OPA, beam steering is performed along the extending direction of the antenna element by changing the wavelength of the input light.

However, in this OPA, in order to secure a practically sufficient beam steering angle range, a tunable laser having an extremely wide wavelength tunable range is required, and the cost of the rider device as a whole increases.

U.S. Pat. No. 8,988,754

Christopher V. Paulton, Ami Yaacobi, David B. Core, Mathew J. Byrd, Manan Raval, Diedrik Vermeulen, Michael R.M. Whats, Coherent solid-state LIDAR with silicon photonic optical phased array, Optics Letters, Vol. 42, No. 20 / October 15, 2017

From the above background, in a rider device using an optical phased array (OPA), a wider beam steering angle range is realized by overcoming the limitation of the beam steering angle range due to the arrangement pitch of the antenna elements without causing an increase in cost. Is required to do.

One aspect of the present invention is configured by a first optical phased array and sends diffracted light generated by light output from a plurality of first antenna elements constituting the first optical phased array to space. The optical transmitter is composed of a second optical phased array, and an optical receiver that receives light coming from the space by a plurality of second antenna elements constituting the second optical phased array. The optical receiver has a plurality of maximum sensitivity directions in which the reception sensitivity of the light is maximized with respect to the direction of the light arriving from the space, and the optical transmitter transmits the diffracted light adjacent to the space. The first angle formed by the directions and the second angle formed by the adjacent maximum sensitivity directions in the optical receiver are different from each other, and the optical transmitter is the plurality of first angles. The diffracted light generated by the light output from the antenna element is sent to the space via the first optical component, and the first angle is sent to the space via the first optical component. Defined by the angle between the adjacent diffracted lights
Light Science system that make up the first optical component is an array pitch of the first antenna element viewed from the light output side of this optical system, the actual arrangement pitch of the first antenna element On the other hand, it is a rider device that shrinks or expands.
According to another aspect of the present invention, the phase shift control unit for controlling the first phase shifter included in the first optical phased array and the second phase shifter included in the second optical phased array is provided. The phase shift control unit controls the phase shift amount of the first phase shifter to change the transmission direction of the main lobe of the diffracted light transmitted by the optical transmitter to the space, and among the maximum sensitivity directions. The phase shift amount of the second phase shifter is controlled so that the maximum sensitivity direction having the maximum sensitivity coincides with the transmission direction of the main lobe.
According to another aspect of the present invention, the arrangement pitch of the said the arrangement pitch of the first antenna element the second antenna element is set to different values.
According to another aspect of the present invention, the ratio of the first angle to the second angle is set to be represented by the ratio of relatively prime natural numbers.
According to another aspect of the present invention, the first and the array pitch of the first antenna element is reduced or enlarged relative to the actual arrangement pitch by an optical system optical components constituting the second antenna the arrangement pitch of the elements, the ratio of which is set as represented by the ratio of relatively prime natural numbers.
According to another aspect of the present invention, the first optical component is an optical component of an afocal optical system composed of two convex lenses.
According to another aspect of the present invention, the first optical component is composed of two prisms constituting an anamorphic prism pair.
According to another aspect of the present invention, the optical receiver receives light coming from the space by the plurality of second antenna elements via the second optical component, and the second angle is the said. for light coming from the space to be received through the second optical component, wherein the maximum sensitivity direction adjacent defined in space is defined by the angle formed with each other, said second optical component that make up light Science system, the array pitch of the second antenna element viewed from the light input side of this optical system is intended to reduce or expand the actual arrangement pitch of the second antenna element ..
Another aspect of the present invention is configured by a first optical phased array and sends diffracted light generated by light output from a plurality of first antenna elements constituting the first optical phased array into space. The optical transmitter is composed of a second optical phased array, and an optical receiver that receives light coming from the space by a plurality of second antenna elements constituting the second optical phased array. The optical receiver has a plurality of maximum sensitivity directions in which the reception sensitivity of the light is maximized with respect to the direction of the light arriving from the space, and the optical transmitter transmits the diffracted light adjacent to the space. The first angle formed by the directions and the second angle formed by the adjacent maximum sensitivity directions in the optical receiver are different from each other, and the optical receiver is the light coming from the space. Is received by the plurality of second antenna elements via the second optical component, and the second angle is the light arriving from the space received via the second optical component. The optical system defined by the angle between the adjacent maximum sensitivity directions defined in space and formed by the second optical component is an arrangement of the second antenna elements viewed from the optical input side of the optical system. The pitch is reduced or expanded with respect to the actual arrangement pitch of the second antenna element.

According to the present invention, in a rider device using OPA, it is possible to overcome the limitation of the beam steering angle range due to the arrangement pitch of the antenna elements and realize a wider beam steering angle range without increasing the cost. it can.

FIG. 1 is a diagram showing a configuration of a lidar device according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram for explaining the operation of the rider device shown in FIG. FIG. 3 is a diagram showing a configuration of a lidar device according to a second embodiment of the present invention. FIG. 4 is a diagram showing a configuration of a rider device according to a third embodiment of the present invention. FIG. 5 is a diagram showing a configuration of a conventional rider device. FIG. 6 is a diagram showing an example of characteristics of a conventional rider device. FIG. 7 is a diagram showing an example of an optical phased array that can be used in a lidar device. FIG. 8 is a diagram showing a configuration of a unit cell included in the optical phased array shown in FIG. 7. FIG. 9 is a diagram showing another example of an optical phased array that can be used in a lidar device.

In general, an OPA is provided in an optical branching device that branches an input light into a plurality of lights, a plurality of waveguide lines propagating each of the plurality of branched lights, and a plurality of waveguide lines. It is composed of a phase shifter that changes the phase of light propagating in a wave line and an antenna element that is connected to each waveguide and outputs light propagating in the waveguide. In addition, OPA is generally reciprocal and can be used in an optical transmitter that emits a light beam that is search light, and can also be used in a receiver that receives the reflected return light of the light beam.

For example, the light received by each of the antenna elements of the OPA is propagated to each waveguide line, the phase is changed by the phase shifter, and then the optical branching device is used as an optical coupler (combiner). An optical receiver can be configured by combining the light propagating through the waveguide line with one light and outputting it.

Here, it is assumed that the OPA is used as an optical transmitter and the phase shift amount in the phase shifter is adjusted so as to transmit diffracted light from the antenna element of the OPA toward space. Then, in this state, it is assumed that the OPA is used as an optical receiver to receive light from the antenna element while maintaining the phase shift amount of the phase shifter. Then, the light arriving from the same direction as the transmission direction of the diffracted light is received by each of the antenna elements and then phase-shifted to the same phase by the phase shifter, and is strongly output in the optical coupler. The Rukoto. On the contrary, the light arriving from a direction different from the transmission direction of the diffracted light does not become the same phase even if it undergoes a phase shift by the phase shifter after being received by each of the antenna elements, and is inside the optical coupler. It will be output without strengthening each other. Therefore, the optical receiver has a maximum receiving sensitivity with respect to the light coming from the transmitting direction of the diffracted light. Further, the optical receiver has the maximum reception sensitivity with respect to the light coming from the transmission direction of the main lobe, which has the maximum intensity of the diffracted light.

Hereinafter, in the present specification, an optical transmitter composed of OPA functioning as a transmitter for transmitting a beam is referred to as TxOPA, and an optical receiver composed of OPA functioning as a receiver for receiving light is referred to as RxOPA. .. Further, in the present specification, for convenience, the diffracted light, the main lobe, and the side lobe, which would be generated by the light transmitted from the antenna element that constitutes RxOPA, are referred to as light. They are referred to as "diffracted light of RxOPA", "main lobe of RxOPA", and "side lobe of RxOPA", respectively. Further, in the present specification, the "far-field image of RxOPA" means a far-field image of light transmitted from the antenna element when light is transmitted from the antenna element constituting the RxOPA 104. ..

Further, in the present specification, the reception sensitivity of RxOPA means the loss received by the light received by the antenna element of the RxOPA before being output from the optical coupler via the phase shifter and the optical coupler of the RxOPA. The reciprocal (that is, the reciprocal of the ratio of the amount of light output from the optical coupler to the total amount of light reaching the antenna element from the same direction).

A rider device that performs three-dimensional spatial mapping or the like can generally be realized by the configuration shown in FIG. The lidar device 500 shown in FIG. 5 includes TxOPA502 and RxOPA504 configured by OPA and a light source 506. The TxOPA502 includes an optical branching device 510 that branches the light from the light source 506, a phase shift unit 514 having a plurality of phase shifters 512 that shift the phase of each light branched by the optical branching device 510, and a phase shift unit. It has an antenna unit 518 in which a plurality of antenna elements 516 that emit each light output from 514 into space are arranged.

Further, the RxOPA504 includes a phase shift unit 524 including an antenna unit 528 in which antenna elements 526 for receiving light propagating in space are arranged, and a plurality of phase shifters 522 for shifting the phases of the light received by each antenna element 526. And an optical coupler 520 that combines the light output by the phase shift unit 524 into one and outputs the light.

The lidar device 500 also includes a photodetector 530 that receives the light output by the RxOPA504, a steering control unit 532 that controls the operation of the phase shift units 514 and 524 of the phase shift units 514 and 524 of the TxOPA502 and RxOPA504, and a steering control unit 532 of the light source 506. A control device 536 that controls the steering control unit 532 and receives the output of the photodetector 530 to perform data generation processing for, for example, spatial mapping.

The light source 506 is, for example, a pulsed laser, and the control device 536 measures the distance to an object in space, for example, by the flight time (TOF) method.

The optical signal from the light source 506 is incident on the TxOPA502. The steering control unit 532 operates the phase shifter 512 of the phase shift unit 514 to emit diffracted light toward space from a plurality of arranged antenna elements 516 constituting the antenna unit 518 of the TxOPA502, and the diffracted light thereof. Beam steering is performed by changing the sending direction to the space.

Further, the steering control unit 532 sets the phase shifter 522 of the phase shift unit 524 of the RxOPA504 so that the diffracted light of the RxOPA504 faces in the same direction as the diffracted light currently transmitted by the TxOPA502. Make it work. As a result, the RxOPA504 has the maximum reception sensitivity with respect to the light arriving from the transmission direction of the main lobe of the TxOPA502, and has the maximum reception sensitivity with respect to the light arriving from the transmission direction of the side lobe of the TxOPA502.

Here, in the conventional lidar device 500, in general, in order to increase the degree of convergence of the diffracted light and increase the spatial resolution in object detection, the number of antenna elements 516 and 526 is required to be several thousand. Further, in general, in order to secure the steering angle range of the main lobe used as the search light as wide as possible, the antenna elements 516 and 526 are arranged at intervals so that diffracted light adjacent to the steering angle range of the main lobe does not enter. Both are designed to be as narrow as possible and, as a result, to have the same spacing p.

As a result, the diffracted light of TxOPA502 and RxOPA504 both have the same direction. FIG. 6 is a diagram showing exemplary characteristics of TxOPA502 and RxOPA504 shown in FIG. The upper part of FIG. 6 shows the TxOPA502 when the optical phase difference generated in each optical path (each channel) from the optical input end of the optical turnout 510 to each optical output end of the antenna element 516 is zero. , Is a far-field image of the light transmitted from the antenna unit 518. Further, in the middle part of FIG. 6, for RxOPA504, the optical phase difference generated in each optical path (each channel) from each optical input end of the antenna element 526 to the optical output end of the optical coupler 520 is zero. It is a figure which shows the distribution of the reception sensitivity of RxOPA504 with respect to the direction of the light coming from space at the time. Further, in the lower part of FIG. 6, when the diffracted light having the light intensity distribution shown in the upper part of FIG. 6 is transmitted to the space and the reflected return light from the space is received by the RxOPA504 having the reception sensitivity distribution shown in the middle part of FIG. It is a figure which showed the distribution of the total sensitivity as the rider device 500 with respect to each direction in the space seen from the rider device 500.

In FIG. 6, the upper, middle, and lower horizontal axes are all axes in which each direction in the XZ plane (the vertical direction shown in FIG. 5) is indicated by a sine value of an angle θ with respect to the Z axis. .. The vertical axis in the upper part of FIG. 6 is the normalized light intensity obtained by normalizing the intensity of the light transmitted from the TxOPA502 with the maximum intensity of the main lobe. The vertical axis in the middle of FIG. 6 is the normalized reception sensitivity obtained by normalizing the reception sensitivity of RxOPA504 with its maximum reception sensitivity value. Further, the lower vertical axis of FIG. 6 is the normalized total sensitivity obtained by normalizing the total sensitivity of the rider device 500 with its maximum value.

In the upper part of FIG. 6, the light intensity portion 600 having the maximum intensity at the position of sinθ = 0 corresponds to the main lobe of the diffracted light output from the TxOPA502 (the main maximum beam having a diffraction order of zero), and the maximum light intensity is concerned. The light intensity portions 602, 604, 606, 608, 610, and 612 other than the portions correspond to side lobes (diffraction light beams having a diffraction order other than zero). Of these, the light intensity portions 602 and 604 correspond to the side lobes (diffraction order is ± 1) adjacent to the main lobe, and are generated at the position of sin θ = ± λ ₀ / p. Here, λ ₀ is the center wavelength of the light output by the light source 506, and p is the array pitch of the antenna element 516.

Since the antenna element 526 of the RxOPA504 is arranged at the same arrangement pitch p as the antenna element 516 of the TxOPA502, the diffracted light of the RxOPA504 faces the same direction as the TxOPA502. Therefore, the reception sensitivity of RxOPA504 shown in the middle part of FIG. 6 is the maximum portion 620 at the same position as the light intensity portions 600, 602, 604, 606, 608, 610, and 612 corresponding to the diffracted light of TxOPA502 in the upper part of FIG. It has 622, 624, 626, 628, 630, and 632, and has a maximum portion 620 that maximizes reception sensitivity at the same position as the light intensity portion 600 corresponding to the main lobe of TxOPA502.

The total sensitivity of the lidar device 500 includes the light intensity distribution transmitted by the TxOPA502 (that is, the value of the normalized light intensity shown in the upper part of FIG. 6) and the reception sensitivity distribution in the RxOPA504 (that is, the normalized value shown in the middle part of FIG. 6). It is proportional to the product of the reception sensitivity value). Therefore, as shown in the lower part of FIG. 6, the total sensitivity of the rider device 500 is the position (mλ ₀ / p, m = 0, ±) where the maximum portion of the light intensity of the TxOPA502 and the maximum portion of the reception sensitivity of the RxOPA504 coincide with each other. In 1, ± 2, ± 3), the maximum portion 640 having the maximum portion 640, 642, 644, 646, 648, 650, 652 and showing the maximum total sensitivity at the position corresponding to the main lobe (sinθ = 0). Have.

In this lidar device 500, when the directions of the diffracted light of TxOPA502 and RxOPA504 are changed in the same manner while generating the same phase shift in each channel of TxOPA502 and each channel of RxOPA504, the light in the upper part of FIG. The strong portion 600 and the like and the maximum portion 620 and the like in the middle of FIG. 6 are shifted in the same direction by the same amount. Further, in response to this, the maximum portion 640 and the like in the lower part of FIG. 6 are also shifted in the same direction by the same amount.

Therefore, for example, when beam steering is performed using the main lobe of TxOPA502 as the search light, in the lower part of FIG. 6, the maximum portion of the total sensitivity when the main lobe is used is within the shift range in the left-right direction shown in the drawing. The range of the beam steering is limited to the range of equation (1) so that the maximum total sensitivities 642, 644 of the adjacent side lobes do not enter.

That is, if α _max ≡ λ ₀ / 2p, the allowable range of the steering angle α is −α _max to + α _max , and as a result, the maximum allowable range of the steering angle α is the arrangement pitch of the antenna elements 516 and 526. It is limited by the size of p.

In the above description, the beam steering in the XZ plane has been described. However, in the YZ plane as well, the beam steering of the antenna elements 516 and 526 depends on the size of the arrangement pitch in the Y-axis direction. The steering angle range is limited.

On the other hand, as an OPA that can be used in a rider device, as described above, an OPA that is configured by arranging a plurality of unit cells, each of which emits light, is known (Patent Document 1). FIG. 7 is a diagram showing a part of the configuration of such OPA700, and FIG. 8 is a diagram showing the configuration of the unit cell 710 constituting the OPA700.

With reference to FIG. 7, the light input from the optical fiber 702 propagates in the column direction bus waveguide 704. The light propagating in the column-direction bus waveguide 704 is branched by a plurality of evanescent couplers 706 provided at predetermined intervals in the column-direction bus waveguide 704 and propagates in the plurality of row-direction bus waveguides 708. Each unit cell 710 (each of the 16 parts shown by the dotted ellipse in the figure) emits a part of the light propagating from the adjacent row direction bus waveguide 708 to the row direction bus waveguide 708 by the evanescent coupler 800 (described later). ) To receive. Further, the column direction control wire 712 and the row direction control wire 714, which are current paths, are connected to each unit cell 710, and the phase shifter 806 (described later) included in each unit cell 710 is selectively energized.

With reference to FIG. 8, each unit cell 710 has an evanescent coupler 800 and an antenna element 802 coupled to the row direction bus waveguide 708, a waveguide 804 connecting the evanescent coupler 800 and the antenna element 802, and the waveguide 804. A phase shifter 806, which is a heater provided in the S-shaped portion of the above, and a column direction electrode 808 and a row direction electrode 810, which are two electrodes for energizing the heater which is the phase shifter 806, are provided. The column direction electrode 808 and the row direction electrode 810 are connected to the column direction control wire 712 and the row direction control wire 714, respectively.

The OPA 700 shown in FIG. 7 can generate a controllable topological vector along the row and / or column directions and can operate as an OPA for controllable beam steering in the XZ and YZ planes. ..

However, in the OPA 700 of FIG. 7 according to Patent Document 1, each unit cell 710 has many additional elements (phase shifter 806, waveguide 804, evanescent coupler 800) in addition to the antenna element 802, so that the size is sufficient. It cannot be made smaller. As a result, in the OPA700 of Patent Document 1, the unit cell 710 (specifically, the antenna element 802 included in the unit cell 710) cannot be arranged with a sufficiently small pitch p in both the X direction and the Y direction. ..

For example, the arrangement pitch of the unit cells 710 realized in the OPA700 is about 9 μm, and when beam steering is performed using light having a center wavelength of 1550 nm, the allowable range of the steering angle α that can be used for the beam steering is , From equation (1), it is limited to ± 5 °.

As another OPA that can be used in the lidar device, as described above, an OPA based on the optical integrated circuit disclosed in Non-Patent Document 1 is known. FIG. 9 is a diagram showing a configuration of OPA900 according to Non-Patent Document 1. The OPA 900 includes a bus waveguide 902 for inputting light, and a portion 904 provided on the bus waveguide 902 and composed of alternately cascaded thermal phase shifters and evanescent couplers. The light branched by the evanescent coupler is connected to the antenna portion 908 in which the grating-based antenna elements are arranged via the waveguide line portion 906, respectively. In this OPA900, the thermal phase shifter controls the phase increment of the light sequentially input to the arranged antenna elements, and controls the wavelength of the light input to the bus waveguide 902 to control the two-dimensional beam. Steering function is provided.

In the TxOPA502 and RxOPA504 shown in FIG. 5, for example, a plurality of grating-based antenna elements constituting the antenna portion 908 of the OPA900 are extended in the Y direction shown in FIG. 5, and the plurality of antenna elements are arranged in the X direction. It can be configured by.

However, the plurality of antenna elements constituting the antenna portion 908 are configured as a waveguide formed on the substrate, and the arrangement pitch of the antenna elements (the arrangement pitch in the X direction) is the waveguide formed. Is equal to the array pitch of. The minimum allowable value of the arrangement pitch of the waveguide is limited by the light confinement strength of the waveguide, and if the refractive index difference between the substrate and the waveguide is increased to increase the light confinement strength, the arrangement pitch of the antenna element can be increased. Can be narrowed. However, there is a limit to the difference in refractive index that can be realized depending on the substrate material and the like, and it is difficult to significantly reduce the arrangement pitch from several μm. Therefore, in the beam steering of the OPA 900 in the X direction, there may be a problem that the steering angle range is limited to about several degrees as in the OPA 700 described above.

Further, in the OPA900, in order to secure a practically sufficient beam steering range in the Y direction, as shown below, a tunable laser having an extremely wide tunable range is required, and the cost of the rider device as a whole increases significantly. Can be done. Conversely, in the OPA900, it may be difficult to achieve a practical beam steering range in the Y direction without a significant increase in cost.

That is, when the oscillation wavelength of the tunable laser changes Δλ with respect to the center wavelength λ ₀ , the steering angle α _y of the main lobe (deflection angle of the main lobe in the YZ plane with respect to the Z axis) emitted from the antenna unit 908 is. Calculated from equation (2).

Here, n _E is the effective refractive index of the waveguide constituting the antenna element, and p _g is the grating pitch provided in each antenna element. The central wavelength λ ₀ of the tunable laser usually satisfies Eq. (3) so that the steering angle α _y becomes zero (α _y = 0) when the wavelength shift is zero (Δλ = 0). Be selected.

Then, when the maximum wavelength change range of the tunable laser is λ ₀ ± Δλ _max , the change range of the steering angle α _y in the Y direction −α _ymax to + α _ymax that can be realized by the _OPA900 is α _ymax in Eq. (4). Is derived from the relationship of.

Here, the grating pitch p _g are usually made at a value close to half the wavelength λ _0/2. if p _g = λ _0/2, equation (4) becomes Equation (5).

That is, when the maximum steering angle α _ymax = 30 °, if the center wavelength λ ₀ is 1550 nm, 2Δλ _max is 775 nm, and a tunable laser capable of controlling the oscillation wavelength over a wide range of 1550 ± 387.5 nm is required. It becomes. It is extremely difficult to find a commercially available tunable laser that satisfies such conditions, or even if it can be found, it is extremely expensive.

Hereinafter, the rider device according to the embodiment of the present invention will be described.
<First Embodiment>
FIG. 1 is a diagram showing a configuration of a lidar device according to a first embodiment of the present invention. The lidar device 100 includes a light source 106, a TxOPA 102 that sends out the output light of the light source 106 to the space, and an RxOPA 104 that receives the reflected return light that is reflected from an object in the space and returned from the light transmitted from the TxOPA 102. , A photodetector 130 for detecting the light output from the RxOPA104. The light source 106 is, for example, a pulse laser.

The TxOPA 102 includes an optical branching device 110 that branches the output light of the light source 106, a phase shift unit 114 that includes a plurality of phase shifters 112 that shift the phase of each light branched by the optical branching device 110, and a phase shift unit. It has an antenna unit 118 in which a plurality of antenna elements 116 that emit each light output from 114 into space are arranged. The antenna elements 116 are arranged two-dimensionally along, for example, the X-axis and the Y-axis shown in the figure so that the distance between them has an arrangement pitch (arrangement interval) p _T in the XY plane defined by the X-axis and the Y-axis. Has been done.

The RxOPA 104 includes an antenna unit 128 in which antenna elements 126 for receiving the reflected return light are arranged, a phase shift unit 124 including a plurality of phase shifters 122 for shifting the phase of the light received by each antenna element 126, and a phase. It has an optical coupler 120 that combines and outputs the light output by the shift unit 124. The antenna elements 126 are arranged two-dimensionally along, for example, the X-axis and the Y-axis shown in the figure so that the distance between them has an arrangement pitch (arrangement interval) p _R in the XY plane defined by the X-axis and the Y-axis. Has been done. As a result, in the RxOPA104, the directions of the plurality of diffracted lights of the RxOPA104 become the maximum sensitivity directions in which the reception sensitivity is maximized. That is, the RxOPA 104 is configured to have a plurality of maximum sensitivity directions in which the reception sensitivity of the light is maximized with respect to the direction of the light arriving from the space.

Here, the TxOPA102 is an optical transmitter composed of a first optical phased array, and is a diffraction generated by light output from a plurality of first antenna elements constituting the first optical phased array. It corresponds to an optical transmitter that sends light to space. The first optical phased array includes an optical turnout 110, a phase shift unit 114 including a phase shifter 112 which is a first phase shifter, and an antenna unit 118 including an antenna element 116 which is a first antenna element. Corresponds to the part containing.

Further, the RxOPA104 is an optical receiver composed of a second optical phased array, and receives light arriving from space by a plurality of second antenna elements constituting the second optical phased array. Corresponds to a vessel. The second optical phased array includes an optical coupler 120, a phase shift unit 124 including a phase shifter 122 which is a second phase shifter, and an antenna unit 128 including an antenna element 126 which is a second antenna element. Corresponds to the part containing.

TxOPA102 and RxOPA104 can be configured using, for example, the OPA described in Patent Document 1. That, TxOPA102 is configured antenna element 802 shown in FIG. 8 for example, the antenna element 116 is arranged two-dimensionally in the XY plane with the X and Y directions to the distance (arrangement pitch) p _T in FIG. Similarly, the RxOPA 104 is configured such that, for example, the antenna element 802 shown in FIG. 8 is arranged two-dimensionally in the XY plane as the antenna element 126 with an interval (arrangement pitch) p _R in the X and Y directions shown in FIG.

Further, the phase shifter 112 of the TxOPA 102 is composed of a phase shifter 806, which is a thermal phase shifter composed of a heater provided on the waveguide 804, as shown in FIG. 8, for example. Similarly, the phase shifter 122 of the RxOPA104 is composed of a phase shifter 806 composed of a heater provided on the waveguide 804, as shown in FIG. 8, for example.

Further, the optical turnout 110 of the TxOPA 102 and the optical coupler 120 of the RxOPA 104 both have a column-direction bus waveguide 704 and a row-direction bus waveguide for propagating light from the light source 106, as shown in FIGS. 7 and 8, for example. It may be composed of 708 and Evanentic couplers 706 and 800.

However, the above configurations of TxOPA102 and RxOPA104 are examples, and the present invention is not limited to this. For example, the antenna units 118 and 128 of the TxOPA 102 and RxOPA 104 are optional as long as the antenna elements 116 and 126, which transmit and receive light, are both two-dimensionally arranged in the illustrated XY plane with the arrangement pitches p _T and p _R , respectively. It can have the structure of.

Further, the phase shift units 114 and 124 are not limited to the above, and are provided in each optical path propagating the light branched by the optical turnout 110 and in each optical path propagating the light received by the antenna element 126, respectively. It can be composed of a phase shifter having an arbitrary configuration. Similarly, the optical turnout 110 and the optical coupler 120 are not limited to the above, as long as they have a function of branching the input light and a function of combining the input light and combining them into one light. In, it may be an optical turnout and an optical coupler that operate according to any configuration or principle.

The lidar device 100 also has a control device 134 and a steering control unit 132 which is a phase shift control unit. The steering control unit 132 controls the operations of the phase shifters 112 and 122 of the TxOPA 102 and the RxOPA 104 under the control of the control device 134. The control device 134 synchronizes the optical pulse output operation of the light source 106 with the operation of the phase shifter 112 of the TxOPA 102 and the phase shifter 122 of the RxOPA 104, and for spatial mapping or the like based on the signal from the photodetector 130. Data generation processing, etc.

That is, according to the above configuration, the rider device 100 causes the steering control unit 132 to generate a desired phase shift in the phase shifters 112 and 122 under the control of the control device 134, and the emission direction of the main lobe of the TxOPA 102 and the maximum reception of the RxOPA 104. While maintaining a state in which the sensitivity directions are oriented in the same direction, beam steering is performed by changing those directions in the X direction and / or the Y direction in the drawing. As a result, the rider device 100 performs beam steering by the main lobe of the TxOPA 102, and receives the reflected return light from the main lobe irradiation direction of the TxOPA 102 by the RxOPA 104.

Further, the lidar device 100 measures the time from the light source 106 emitting the light pulse to the reception of the reflected return light of the light pulse via the RxOPA 104 by the control device 134, thereby irradiating the main lobe of the TxOPA 102. The distance to an object existing in the direction is calculated by the flight time method. Then, the lidar device 100 sequentially detects the reflected return light coming from the emission direction of the main lobe of the TxOPA 102, which changes sequentially according to the beam steering operation, and detects the distance to the object in the sequentially changing direction. , For example, generate data for spatial mapping and the like.

In particular, in the rider device 100 according to the present embodiment, the arrangement pitch p _T of the antenna element 116 of the TxOPA 102 and the arrangement pitch p _R of the antenna element 126 of the RxOPA 104 have different values, for example, in the equation (6). It is set to have a relationship. Here, N ₁ / M ₁ is an irreducible function, and M ₁ and N ₁ are coprime natural numbers.

As a result, the rider device 100 has an array pitch of the antenna element 116 of the TxOPA 102 as compared with a conventional rider device (for example, the rider device 500) configured by using TxOPA and RxOPA having the same value p for the antenna element arrangement pitch. It is possible to perform beam steering by changing the steering angle α of the main lobe of the TxOPA 102 in a wider range without reducing p _T with respect to the above p. This will be described below.

In the following description, for the sake of simplicity, a beam steering operation in the X-axis direction will be described as an example. As will be apparent to those skilled in the art, the description holds true in the Y-axis direction orthogonal to the X-axis.

As described above, the rider device 100 according to the present embodiment is configured such that the arrangement pitch p _T of the antenna element 116 of the TxOPA 102 and the arrangement pitch p _R of the antenna element 126 of the RxOPA 104 have different values. There is. Therefore, the first angle formed by the directions of the adjacent diffracted light transmitted by the TxOPA 102 into the space and the second angle formed by the directions of the adjacent diffracted light of the RxOPA 104, that is, the adjacent maximum sensitivity directions are mutually formed. It is different.

Therefore, if the TxOPA102 and RxOPA104 are controlled so that the directions of the main lobes of the TxOPA102 and RxOPA match, the directions of the side lobes adjacent to the main lobes will be different between the TxOPA102 and the RxOPA104. That is, since the reception sensitivity of RxOPA104 in the direction of the adjacent sidelobes transmitted from the TxOPA102 does not have a maximum value, reception of light arriving from the direction of the adjacent sidelobes is suppressed. As a result, the steering angle range of the main lobe of the TxOPA 102 is not limited by the angle between the main lobe and the side lobes adjacent thereto, and a wider steering angle range can be used.

More specifically, the difference Δω _T in the sine value of the deflection angle of the adjacent diffracted light of TxOPA102 (the angle with respect to the Z axis in the figure) and the difference Δω _R of the sine value of the deflection angle of the adjacent diffracted light of RxOPA104 are the equations, respectively. It is represented by (7) and equation (8).

Further, the equation (9) holds from the equations (6), (7) and (8).

That is, in the lidar device 100, the ratio of the first angle formed by the directions of the adjacent diffracted lights transmitted by the TxOPA 102 into the space and the second angle formed by the adjacent maximum sensitivity directions of the RxOPA 104 are relatively prime. It is set to be represented by the ratio of natural numbers.

Equation (9) can be expressed as Equation (10).

That is, when the direction of the main lobe of TxOPA102 and RxOPA104 are the same, the direction of the M ₁ th sidelobe counted from a main lobe in TxOPA102, the direction of the N ₁ -th sidelobe counted from a main lobe in RxOPA104 However, it will be the first match. In other words, for the reflected light of the _1st to M1-1st side lobes in TxOPA102, reception in RxOPA104 is suppressed.

As a result, the permissible change range of the steering angle α of the main lobe of the TxOPA102 −α _max to + α _max α _max is determined by the equation (11).

That is, as can be seen from the comparison between the equation (1) and the equation (11), the arrangement pitch p _T of the antenna element 116 of the TxOPA 102 constituting the rider device 100 is set to the arrangement pitch p of the TxOPA502 of the conventional rider device 500. Even so (ie, without setting the array pitch p _T to a value smaller than p), the permissible angle range of the beam steering of the rider device 100 is improved to M times the permissible angle range of the conventional rider device 500.

FIG. 2 is a diagram for explaining the operation of the rider device 100 when N = 5 and M = 6 in the equation (6). The upper part of FIG. 2 is a diagram showing an example of a far-field image of light transmitted from the antenna unit 118 of TxOPA102, and the middle part of FIG. 2 is a diagram showing a light reception sensitivity distribution in RxOPA104. Further, the lower part of FIG. 2 is a diagram showing the distribution of the total sensitivity in the lidar device 100 obtained as the product of the light intensity and the reception sensitivity shown in the upper part and the middle part of FIG. 2, respectively. The horizontal axis of FIG. 2 is a sine value sin θ of an angle θ with respect to the Z axis direction in the XZ plane. The vertical axis in the upper part of FIG. 2 is the normalized light intensity normalized by the maximum light intensity, the vertical axis in the middle part of FIG. 2 is the normalized reception sensitivity normalized by the maximum reception sensitivity, and the vertical axis in the lower part of FIG. 2 is the total sensitivity. It is the total normalized sensitivity normalized by the maximum value of.

In the light intensity distribution of TxOPA102 shown in the upper part of FIG. 2, the positions of the sixth side lobes 202 and 204, which are Mth from the main lobe 200 of TxOPA102 existing at the position of sinθ = 0, and the positions of RxOPA104 shown in the middle part of FIG. In the reception sensitivity distribution, the positions of the maximum sensitivity portions 212 and 214 corresponding to the fifth side lobe, which is the Mth from the maximum intensity portion 210 corresponding to the main lobe of RxOPA104 existing at the position of sin θ = 0, are one. I am doing it.

Therefore, as shown in the lower part of FIG. 2, the distribution of the total sensitivity in the lidar device 100 is adjacent to the maximum sensitivity 220 having the maximum sensitivity at the position of sinθ = 0 corresponding to the main lobes of the TxOPA102 and RxOPA104. The maximum portions 222 and 224 of the total sensitivity to be used appear at a position of sin θ = ± 6λ ₀ / p _T (= ± 5λ ₀ / p _R ) at a great distance. As a result, the rider 100, by controlling the phase shifters 112 and 122 so that the direction of the main lobe direction and RxOPA104 of the main lobe of TxOPA102 match, reduce the arrangement pitch p _T of the antenna element 116 of TxOPA102 As shown in the equation (11), the range of change of the beam stelling angle α of the main lobe of the TxOPA 102 can be expanded to M times, that is, 6 times, as compared with the conventional lidar device.

Specifically, the rider device 100 according to the present embodiment operates as follows. In the following description, for the sake of simplicity, it is assumed that beam steering is performed in the X-axis direction shown in the drawing. However, as understood by those skilled in the art, by performing the beam steering operation in the Y-axis direction in the drawing similar to the beam steering operation in the X-axis direction in accordance with the beam steering operation in the X-axis direction shown below, 2 A dimensional beam steering operation can be performed.

First, the control device 134 of the lidar device 100 controls the light source 106 to generate optical pulses at regular time intervals. Further, the control device 134 instructs the steering control unit 132 to perform beam steering by changing the deflection angle α (steering angle α) in the X direction of the main lobe transmitted from the TxOPA 102 to the space. More specifically, the steering control unit 132 has such that the phase of the light emitted from each antenna element 116 has a linear phase inclination along the X axis according to the deflection angle α, and the deflection angle α. Controls the phase shifter 112 so that is temporally changed in a predetermined pattern within a predetermined steering angle range. Here, the linear phase gradient according to the deflection angle α is the phase shift amount generated in each optical path (each channel) from the optical input end of the optical turnout 110 to the output end of each antenna element 116 in the equation (12). ), This can be realized by setting each phase shifter 122.

Here, q is an index assigned to each of the antenna elements 116 corresponding to each channel in order from the end along the position of the antenna element 116 on the X axis, and q = −Q, ..., -1, 0, 1, ..., Q.

Further, the control device 134 instructs the steering control unit 132 to control the phase shifter 122 so that the main lobe of the RxOPA 104 has the same deflection angle α as the main lobe of the TxOPA 102. Specifically, in the steering control unit 132, the phase shift amount generated in each optical path (each channel) from the optical receiving end of each antenna element 126 to the optical output end of the optical coupler 120 follows the equation (13). Each phase shifter 122 is set to.

Here, s is an index assigned to each of the antenna elements 126 corresponding to each channel in order from the end along the position of the antenna element 126 on the X axis, and q = −S, ..., -1,. 0, 1, ..., S. From equations (12) and (13), the phases φ _T (u) and φ _R (u) to be generated in each channel corresponding to the antenna elements 116 and 126 having the same index value u are expressed in equation (14). Meet.

That is, the phase shift generated in each channel of RxOPA104 needs to be p _R / p _T times the phase shift generated in each channel of TxOPA102.

Further, the control device 134 controls the main lobes of the TxOPA 102 and the RxOPA 104 in the same direction as described above, and the optical pulse output from the light source 106 and transmitted as the main lobe from the TxOPA 102 is received from the main lobe direction of the RxOPA 104. The time to reach is measured, and the distance to the object existing in the main lobe direction is calculated. This allows the control device 134 to generate, for example, spatial mapping data within the beam steering range of the main lobe of the TxOPA 102.

In the present embodiment, the arrangement pitch p _T of the antenna unit 118 of the TxOPA 102 and the arrangement pitch p _R of the antenna unit 128 of the RxOPA 104 are configured to have the relationship of the equation (6). Not limited to. For example, even if the array pitches p _T and p _R have different values, the side lobes of the TxOPA 102 and the Rx OPA 104 may be different from each other to allow the steering angle of the main lobe of the TxOPA 102 to be within the allowable range. Can be expanded.

Further, even if the actual array pitch p _T of the antenna unit 118 and / or the actual array pitch p _R of the antenna unit 128 does not look at the equation (6), for example, the beam emitting portion of the antenna element 116 of the TxOPA 102 and / or the RxOPA 104 By arranging optical components such as lenses that constitute an image conversion optical system at the beam arrival portion of the antenna element 126 of the above, a substantial array pitch p converted from diffracted light emitted from the TxOPA 102 via these optical components. _{If the} substantial array pitch p _Re converted from the reception sensitivity of the light received by the RxOPA104 via _Te and / or their optics is different from each other (for example, if the equation (6) is satisfied), the above Similarly, the allowable range of the steering angle of the main lobe of the TxOPA102 can be expanded.

In other words, the first angle formed by the directions of the adjacent diffracted lights transmitted by the TxOPA102 into the space is such that the diffracted light of the TxOPA102 is transmitted to the space via the optical components constituting the image conversion optical system. It is defined by the angle between adjacent diffracted lights sent into space via the optics. Further, the second angle formed by the adjacent maximum sensitivity directions in the RxOPA104 is before passing through the optical component when the RxOPA104 receives light from the space via the optical component constituting the image conversion optical system. It is defined as the angle between adjacent maximum sensitivity directions in the space. Then, as described above, the ratio between the first angle and the second angle is relatively prime so that the first angle and the second angle have different values (for example, the ratio between the first angle and the second angle is relatively prime. If it is set (to be a ratio of natural numbers), the allowable range of the steering angle of the main lobe of the TxOPA 102 can be expanded by the same principle as described above.

<Second Embodiment>
Next, the rider device according to the second embodiment of the present invention will be described.
FIG. 3 is a diagram showing a configuration of a lidar device 300 according to a second embodiment of the present invention. In FIG. 3, for the same components as the lidar device 100 according to the first embodiment shown in FIG. 1, the same reference numerals as those shown in FIG. 1 shall be used, and the above description of the rider device 100 shall be incorporated. And.

The lidar device 300 has the same configuration as the rider device 100, except that the optical unit 346 constituting the image conversion optical system is arranged on the light transmitting side of the antenna unit 118 of the TxOPA 102. The image conversion optical system composed of the optical unit 346 in the present embodiment is, for example, a two-lens system having an image magnification K ₁ composed of lenses 342 and 344, which are two convex lenses having focal lengths f ₁ and f ₂ , respectively. It is composed of.

Since the lidar device 300 having the above configuration includes an optical unit 346 having an image magnification K ₁ on the light transmitting side of the TxOPA 102, the TxOPA 102 is substantially K at a position of a distance f ₂ from the lens 344 to the right side in the drawing. _It functions as an OPA equipped with antenna elements 316 arranged at a _1- fold arrangement pitch K ₁ · p _T. Therefore, by configuring the optical unit 346, TxOPA102, and RxOPA104 so that K ₁ · p _T ≠ p _R , the TxOPA 102 sends out to the space in the same manner as the rider device 100 according to the first embodiment. by varying the first angle adjacent diffracted light forms each other and a second angle adjacent local maximum sensitivity direction forms each other in the space in RxOPA104, without reducing the p _T, of the main lobe of TxOPA102 The allowable range of steering angle can be expanded.

For example, in the present embodiment, the optical unit 346, TxOPA102, and RxOPA104 are configured so that the image magnification K ₁ and the arrangement pitch p _T , p _R satisfy the equation (15).

Here, as in Eq. (6), N ₂ / M ₂ is an irreducible function, and M ₂ and N ₂ are coprime natural numbers. The image magnification K ₁ is given by the equation (16) using the focal lengths f ₁ and f ₂ of the two lenses 342 and 344 constituting the optical unit 346.

At this time, the difference Δω _T2 of the sine values of the deflection angles of the adjacent diffracted light transmitted from the TxOPA 102 to the space through the optical unit 346 is given by the equation (17).

Since the lens optical system is not arranged in the RxOPA104, the difference Δω _R of the sine values of the deflection angles of the adjacent diffracted light (that is, the adjacent reception sensitivity maximum direction) in the RxOPA104 is the same as that of the lidar device 100. It is given in (8).

Equation (18) is obtained from the above equations (15), (17), and equation (8).

That is, of the diffracted light TxOPA102 sent into space from the optical unit 346, and the direction of M ₂ th sidelobe counted from the main lobe of TxOPA102, direction of N ₂ th sidelobe counted from a main lobe in RxOPA104 And, can be seen to match.

Therefore, the permissible variable range of the steering angle α of the main lobe sent from the optical unit 346 to the space −α _{max to} α _max α _max is given by the equation (19).

That is, expanded in the rider device 300, similarly to the rider 100, without reducing the array pitch p _T of the antenna element 116 of TxOPA102, the permissible range of the steering angle of the main lobe to be delivered to the space output from TxOPA102 can do. In particular, in the lidar device 300, the substantial arrangement pitch of the antenna element 116 of the TxOPA 102 as seen from the optical output side of the optical unit 346 is the arrangement pitch p _T of the TxOPA 102 itself and the image magnification K ₁ of the optical unit 346. Since it is given by the product of K ₁ p _T , the degree of freedom in design can be further improved as compared with the rider device 100.

Specifically, the rider device 300 according to the present embodiment operates as follows. In the following description, for the sake of simplicity, it is assumed that beam steering is performed in the X-axis direction shown in the drawing. However, as understood by those skilled in the art, by performing the beam steering operation in the Y-axis direction in the drawing similar to the beam steering operation in the X-axis direction in accordance with the beam steering operation in the X-axis direction shown below, 2 A dimensional beam steering operation can be performed.

The rider device 300 according to the present embodiment operates in the same manner as the rider device 100 described above, but the operation of the steering control unit 332 is slightly different from that of the steering control unit 132. The steering control unit 332 performs beam steering by changing the deflection angle α (steering angle α) of the main lobe transmitted from the TxOPA 102 to the space in the X direction. More specifically, the steering control unit 332 has such that the phase of the light emitted from the virtual antenna element 316 formed by the image conversion has a linear phase gradient according to the deflection angle α along the X axis. In addition, the phase shifter 112 is controlled so that the deflection angle α changes temporally in a predetermined pattern within a predetermined steering angle range. Here, the linear phase gradient according to the deflection angle α is the phase shift amount generated in each optical path (each channel) from the optical input end of the optical turnout 110 to the output end of each antenna element 116 in the equation (20). ), This is realized by setting each phase shifter 122.

Here, q is an index assigned to each of the antenna elements 116 corresponding to each channel in order from the end along the position of the antenna element 116 on the X axis, and q = −Q, ..., -1, 0, 1, ..., Q.

The phase shift amount generated in each channel of the RxOPA 104 by the phase shifter 122 so that the main lobe of the RxOPA 104 has the same deflection angle α as described above is given by the equation (13) as in the case of the lidar device 100. ..

Similar to equation (14), from equations (13) and (20), the phases φ _T2 (u) and φ _R () to be generated in each channel corresponding to each of the antenna elements 116 and 126 having the same index value u ( u) satisfies the equation (21).

That is, the phase shift generated in each channel of RxOPA104 needs to be p _R / (K ₁ · p _T ) times the phase shift generated in each channel of TxOPA102.

In the present embodiment, the rider device 300 is configured by using TxOPA102 and RxOPA104 having different arrangement pitches p _T and p _R , but is not limited to this. In the rider device 300, the array pitches p _T and p _R may have the same value as long as the equation (15) is satisfied. That is, the rider device 300 can be configured by using TxOPA and RxOPA having the same arrangement spacing of the respective antenna elements instead of TxOPA102 and RxOPA104.

<Third Embodiment>
Next, the rider device according to the third embodiment of the present invention will be described.
In the lidar device 300 according to the second embodiment described above, the substantially arrangement pitch of the antenna element 116 of the TxOPA 102 is expanded by the optical unit 346 which is an image conversion optical system composed of a two-lens system. On the other hand, in the third embodiment, an anamorphic prism pair is used as the image conversion optical system to expand the substantial arrangement pitch of the antenna elements 116 in the one-dimensional direction.

FIG. 4 is a diagram showing a configuration of a lidar device 400 according to a third embodiment of the present invention. In FIG. 4, for the same components as the lidar device 100 according to the first embodiment shown in FIG. 1, the same reference numerals as those shown in FIG. 1 shall be used, and the above description of the rider device 100 shall be incorporated. And.

The lidar device 400 has the same configuration as the rider device 100, but an optical unit 446 composed of an anamorphic prism pair consisting of two prisms 442 and 444 is arranged on the light transmitting side of the antenna unit 118 of the TxOPA102. The point is different.

In this embodiment, the anamorphic prism pair consisting of two prisms 442 and 444 is configured to magnify the image in the illustrated X direction. Therefore, the beam steering of the main lobe of the TxOPA 102 in the Y direction shown in the drawing is the same as that of the rider device 100 according to the first embodiment shown in FIG.

Since the lidar device 400 having the above configuration includes an optical unit 446 having an image magnification K ₂ in the illustrated X direction on the light transmitting side of the TxOPA 102, the TxOPA 102 is substantially the light of the prism 444 on the light output side. It functions as an OPA equipped with antenna elements 416 arranged at a distance D from the output surface (right side surface in the drawing) to the left side in the drawing with an arrangement pitch of K ₂ · p _T of ₂ times K. Therefore, by configuring the optical unit 446, TxOPA102, and RxOPA104 so that K ₂ · p _T ≠ p _R , the first is the same as that of the rider device 100 according to the first embodiment in the X direction. Similar to the lidar device 100 according to the embodiment of the above, the first angle formed by the adjacent diffracted lights transmitted by the TxOPA 102 into the space and the second angle formed by the adjacent maximum sensitivity directions in the space in the RxOPA 104. the varied, without reducing the p _T, it is possible to expand the allowable range of the steering angle of the main lobe of TxOPA102. In the Y direction, the rider device 400 operates in the same manner as the rider device 100, and the allowable range of the steering angle of the main lobe of the TxOPA 102 is expanded without reducing the pT like the rider device 100.

For example, in the present embodiment, the optical unit 446, TxOPA102, and RxOPA104 are configured so that the image magnification K ₂ , the array pitch p _T , and p _R satisfy the equation (22).

Here, as described above, since the optical unit 446 magnifies the image only in the X direction, in the rider device 400, the beam steering of the main lobe of the TxOPA 102 in the Y direction shown in the drawing is the first embodiment shown in FIG. This is the same as the rider device 100 according to the embodiment. Therefore, in the following, the beam steering in the illustrated X direction will be described.

In the above equation (22), N ₃ / M ₃ is an irreducible function, and M ₃ and N ₃ are coprime natural numbers. At this time, the difference Δω _T3 of the sine values of the deflection angles of the adjacent diffracted light transmitted from the TxOPA 102 to the space through the optical unit 446 is given by the equation (23).

Since the lens optical system is not arranged in the RxOPA104, Δω _R is the same as that of the lidar device 100 due to the difference in the sine values of the deflection angles of the adjacent diffracted light (that is, the adjacent reception sensitivity maximum direction) in the RxOPA104. It is given by the equation (8).

Equation (24) is obtained from the above equations (22), (23), and (8).

That is, of the diffracted light TxOPA102 sent into space from the optical unit 446, and the direction of M ₃ th sidelobe counted from the main lobe of TxOPA102, direction N ₃ th sidelobe counted from a main lobe in RxOPA104 And, can be seen to match.

Therefore, the permissible variable range of the steering angle α of the main lobe sent from the optical unit 446 to the space − α _{max to} α _max α _max is given by the equation (25).

That is, in the X direction of the beam steering operation of the rider 400, similarly to the rider 100, without reducing the array pitch p _T of the antenna element 116 of TxOPA102, of the main lobe to be delivered to the space output from TxOPA102 The allowable range of steering angle can be expanded. In particular, the rider 400, the antenna element 116 of TxOPA102, substantial sequence pitch in X-direction as viewed from the light output side of the optical unit 446, the array pitch p _T of itself TxOPA102, the image magnification of the optical unit 446 Since it is given by the product of K ₂ and K ₂ p _T , the degree of freedom in design can be further improved as compared with the rider device 100.

The image magnification K ₂ can be determined from the geometric shapes and arrangements of the prisms 442 and 444 forming the anamorphic prism pair in the optical unit 446 according to the prior art. Similarly, the distance D that defines the actual position of the antenna element 416 formed by the presence of the optical unit 446 is determined from the image magnification K ₂ and the distance from the antenna element 116 to the prism 442 according to the prior art. obtain.

Specifically, the rider device 400 according to the present embodiment operates as follows.
The rider device 400 operates in the same manner as the rider device 100 described above, but the operation of the steering control unit 432 is different from that of the steering control unit 132. Similar to the steering control unit 132, the steering control unit 432 changes the deflection angle α (steering angle α) of the main lobe sent from the TxOPA 102 to the space via the optical unit 446 in the X direction. The phase of the light emitted from the antenna element 116 via the optical unit 446 has a linear phase gradient along the X axis according to the deflection angle α, and the deflection angle α is within a predetermined steering angle range. The phase shifter 112 is controlled so as to change with time in a predetermined pattern. Here, the linear phase gradient according to the deflection angle α is the phase shift amount generated in each optical path (each channel) from the optical input end of the optical turnout 110 to the output end of each antenna element 116 in the equation (26). ), This is realized by setting each phase shifter 122.

Here, q is an index assigned to each antenna element 116 constituting the antenna unit 118 in order from the end along the position of the antenna element 116 on the X axis, and q = −Q, ..., -1, 0, 1, ..., Q.

The linear phase inclination generated by the phase shifter 122 so that the main lobe of the RxOPA 104 has a deflection angle α is given by the equation (13) as in the case of the lidar device 100.

Similar to equation (14), from equations (13) and (26), the phases φ _T3 (u) and φ _R () to be generated in each channel corresponding to each of the antenna elements 116 and 126 having the same index value u ( u) satisfies the equation (27).

That is, the phase shift generated in each channel of RxOPA104 needs to be p _R / (K ₂ · p _T ) times the phase shift generated in each channel of TxOPA102.

In the present embodiment, the rider device 400 is configured by using TxOPA102 and RxOPA104 having different arrangement pitches p _T and p _R , but is not limited to this. In the lidar device 400, the array pitch p _T and p _R may have the same value as long as the equation (22) is satisfied. That is, the rider device 300 can be configured by using TxOPA and RxOPA having the same arrangement spacing of the respective antenna elements instead of TxOPA102 and RxOPA104.

The present invention is not limited to the configuration of each of the above embodiments, and can be implemented in various embodiments without departing from the gist thereof.

For example, in each of the above embodiments, the antenna element 116 of the TxOPA 102 and the antenna element 126 of the RxOPA 104 are arranged in the XY plane with the same arrangement pitch p _T and p _R in the X direction and the Y direction. Is not limited. The antenna element 116 of the TxOPA 102 and the antenna element 126 of the RxOPA 104 may be configured so that the arrangement pitches in the X direction and the Y direction are different.

In this case, in each of the X and Y directions, the first angle formed by the adjacent diffracted lights transmitted by the TxOPA 102 into the space and the adjacent maximum sensitivity direction in the space in the RxOPA 104 are the second formed with each other. By making the angles different, the allowable range of the steering angle in the X direction and the Y direction of the main lobe of the TxOPA 102 can be expanded together without reducing the arrangement pitch in the X direction and the Y direction.

Specifically, the arrangement pitches of the substantial antenna elements of TxOPA102 and RxOPA104 are different from each other (for example, their ratios) in consideration of the image magnification of the optical components that can be provided in the light emitting part of TxOPA102 and the light receiving part of RxOPA104. The permissible range of the steering angle of the main lobe of the TxOPA102 can be expanded by setting (so that is represented by a natural number that is relatively prime).

Further, in each of the above embodiments, TxOPA102 and RxOPA104 have been described as being configured by using OPA having reciprocity for the sake of simplicity, but the present invention is not limited to this. For example, the RxOPA 104 may propagate light in one direction from the antenna element 126 to the light output end of the optical coupler 120. Even in this case, the maximum sensitivity direction is defined for each channel from each antenna element 126 to the optical output end of the optical coupler 120 in consideration of the virtual diffracted light when the light is virtually propagated in the opposite direction. However, the range of beam steering can be expanded by using the same configuration as each of the above-described embodiments.

Further, in each of the above embodiments, TxOPA102 and RxOPA104 are configured by using OPA700 as shown in Patent Document 1 as an example, but the present invention is not limited to this. As another example, TxOPA102 and RxOPA104 can be configured by using OPA900 as disclosed in Non-Patent Document 1, for example. Specifically, for example, the extending direction of the antenna elements of the glazing base is aligned with the Y direction in FIG. 1, and the antenna elements are arranged in the X direction of FIG. 1 to constitute TxOPA102 and RxOPA104. Can be. In this case, the allowable angle range of the beam steering is expanded for the beam steering in the X direction by the same configuration as each of the above-described embodiments, where the arrangement pitches of the antenna elements in the TxOPA102 and RxOPA104 are p _T and p _R , respectively. be able to.

Further, in the second and third embodiments, FIGS. 3 and 4 are drawn assuming that the optical units 346 and 446 constituting the image conversion optical system have image magnifications K ₁ and K ₂ larger than 1, respectively. However, it is not limited to this. The image magnifications K ₁ and K ₂ may have values smaller than 1. Further, the image conversion optical system can be any optical system as long as it has a function of performing image conversion in at least one dimension direction.

As described above, the lidar device 100 and the like according to the embodiment of the present invention include the TxOPA 102 which is an optical transmitter configured by an optical phased array. The TxOPA 102 sends diffracted light generated by the light output from the antenna element 116, which is a plurality of first antenna elements constituting the optical phased array, to the space. Further, the lidar device 100 and the like include RxOPA104, which is an optical receiver configured by an optical phased array. The RxOPA 104 receives light coming from space by antenna elements 126, which are a plurality of second antenna elements constituting the optical phased array. Then, in the lidar device 100 and the like, the optical receiver RxOPA104 has a plurality of maximum sensitivity directions in which the reception sensitivity of the light is maximized with respect to the direction of the light arriving from the space. Further, in the lidar device 100 or the like, the first angle formed by the directions of the adjacent diffracted light transmitted from the optical transmitter TxOPA 102 to the space and the adjacent maximum sensitivity direction in the optical receiver RxOPA 104 form each other. The second angle is different from each other.

According to this configuration, the reflected return light of the side lobe adjacent to the main lobe transmitted from the TxOPA 102 to the space is suppressed and output in the RxOPA 104. Therefore, the rider 100 and the like, without increasing the cost, to overcome the limitations of the beam steering angle range due to the angular spacing between adjacent diffraction lights determined by the arrangement pitch p _T of the antenna element 116 of TxOPA102, A wider beam steering angle range can be achieved.

Further, the lidar device 100 and the like include a phase shifter 112 which is a first phase shifter included in the optical phased array constituting the TxOPA 102, a phase shifter 122 which is a second phase shifter included in the optical phased array constituting the RxOPA 104, and the like. The steering control unit 132 and the like, which are phase shift control units for controlling the above, are provided. Then, the steering control unit 132 or the like, which is a phase shift control unit, controls the phase shift amount of the phase shifter 112, which is the first phase shifter, and the main lobe of the diffracted light transmitted to the space by the optical transmitter TxOPA 102. Change the sending direction. Further, the steering control unit 132 or the like, which is a phase shift control unit, is a second phase shifter so that the maximum sensitivity direction having the maximum sensitivity among the maximum sensitivity directions coincides with the transmission direction of the main lobe of the TxOPA 102. The phase shift amount of the phase shifter 122 is controlled.

According to this configuration, the reception sensitivity of the RxOPA 104 to the reflected return light coming from the transmission direction of the main lobe of the TxOPA 102 can always be maintained at the maximum.

Further, in the rider device 100 or the like, the arrangement interval p _T of the antenna element 116 which is the first antenna element and the arrangement interval p _R of the antenna element 126 which is the second antenna element are set to different values. .. According to this configuration, the first angle formed by the directions of the adjacent diffracted light transmitted by the TxOPA 102 into the space and the second angle formed by the adjacent maximum sensitivity directions in the RxOPA 104 are easily different from each other. can do.

Further, in the rider device 100 or the like, the ratio of the first angle to the second angle is set so as to be represented by the ratio of coprime natural numbers. According to this configuration, the permissible angle range of the beam steering of the TxOPA102 can be expanded by a magnification determined by the natural number, for example, as shown by the equation (11).

Further, in the rider device 100 or the like, the ratio of the arrangement interval p _T of the antenna element 116 which is the first antenna element and the arrangement interval p _R of the antenna element 126 which is the second antenna element is a ratio of natural numbers which are relatively prime to each other. It is set to be represented. According to this configuration, the ratio between the first angle and the second angle can be easily set so as to be represented by the ratio of coprime natural numbers.

Further, in the lidar devices 300 and 400, the optical transmitter TxOPA 102 constitutes an image conversion optical system with diffracted light generated by light output from antenna elements 116 which are a plurality of first antenna elements. It is sent out to space via the lenses 342 and 344 or the prisms 442 and 444, which are the optical components of 1. Then, in the lidar devices 300 and 400, the first angle is defined by the angle between adjacent diffracted lights transmitted to the space via the first optical component.

According to this configuration, in addition to the arrangement pitch p _T of the antenna element 116 of the TxOPA 102 and the arrangement pitch p _R of the antenna element 126 of the RxOPA 104, the first angle is set by using the image magnification of the image conversion optical system. Because it can be done, the degree of freedom in design is improved.

Further, in the lidar device 300, the first optical component is composed of two convex lenses, lenses 342 and 344. According to this configuration, the image conversion optical system can be easily constructed.

Further, in the lidar device 400, the first optical component is composed of two prisms 442 and 444 forming an anamorphic prism pair. According to this configuration, the image conversion optical system can be easily constructed.

Further, in the lidar device 100 and the like, the optical receiver RxOPA104 transmits the light coming from the space through the second optical component constituting the image conversion optical system, and the antenna element 126 which is a plurality of second antenna elements. Can be received by. In this case, the second angle is defined as the angle formed by the adjacent maximum sensitivity directions defined in the space for the light arriving from the space received via the second optical component. .. According to this configuration, the degree of freedom in designing the rider device 100 and the like can be further improved.

100, 300, 400, 500 ... Rider device, 102, 502 ... TxOPA, 104, 504 ... RxOPA, 106, 506 ... Light source, 110, 510 ... Optical turnout, 112, 122, 512, 522 ... Phase shifter, 114, 124, 514, 524 ... Phase shift unit, 116, 126, 516, 526 ... Antenna element, 118, 128, 518, 528 ... Antenna unit, 120, 520 ... Optical coupler, 130, 530 ... Photodetector, 132, 532 ... Steering control unit, 134, 536 ... Control device, 346, 446 ... Optical unit, 342, 344 ... Lens, 442, 444 ... Prism, 700, 900 ... OPA.

Claims (9)

An optical transmitter composed of a first optical phased array and transmitting diffracted light generated by light output from a plurality of first antenna elements constituting the first optical phased array to space.
An optical receiver composed of a second optical phased array and receiving light coming from the space by a plurality of second antenna elements constituting the second optical phased array.
With
The optical receiver has a plurality of maximum sensitivity directions in which the reception sensitivity of the light is maximized with respect to the direction of the light arriving from the space.
The first angle formed by the directions of the adjacent diffracted light transmitted by the optical transmitter to the space and the second angle formed by the adjacent maximum sensitivity directions in the optical receiver are different from each other. And
The optical transmitter transmits the diffracted light generated by the light output from the plurality of first antenna elements to the space via the first optical component.
The first angle is defined as the angle between the adjacent diffracted lights delivered into the space via the first optical component.
Light Science system that make up the first optical component is an array pitch of the first antenna element viewed from the light output side of this optical system, the actual arrangement pitch of the first antenna element On the other hand, it shrinks or expands,
Rider device. A phase shift control unit for controlling a first phase shifter included in the first optical phased array and a second phase shifter included in the second optical phased array is provided.
The phase shift control unit controls the phase shift amount of the first phase shifter to change the transmission direction of the main lobe of the diffracted light transmitted by the optical transmitter to the space, and the maximum of the maximum sensitivity directions. The phase shift amount of the second phase shifter is controlled so that the maximum sensitivity direction having sensitivity coincides with the transmission direction of the main lobe.
The rider device according to claim 1. The first and the arrangement pitch of the antenna element and the array pitch of the second antenna element is set to different values,
The rider device according to claim 1 or 2. The ratio of the first angle to the second angle is set to be represented by the ratio of relatively prime natural numbers.
The rider device according to any one of claims 1 to 3. The arrangement pitch of the shrinking to the actual array pitch by the optical system or enlarged the first antenna element, wherein the first optical component is configured, the array pitch of the second antenna element, the ratio of It is set to be represented by the ratio of relatively prime natural numbers,
The rider device according to claim 4. The first optical component is an optical component of an afocal optical system composed of two convex lenses.
The rider device according to any one of claims 1 to 5. The first optical component is composed of two prisms constituting an anamorphic prism pair.
The rider device according to any one of claims 1 to 5. The optical receiver receives light coming from the space through the second optical component by the plurality of second antenna elements.
The second angle is defined as an angle formed by the adjacent maximal sensitivity directions defined in the space for light arriving from the space received via the second optical component.
Light Science system that make up the second optical component is an array pitch of the second antenna element viewed from the light input side of this optical system, the actual array pitch of the second antenna element On the other hand, it shrinks or expands,
The rider device according to any one of claims 1 to 7. An optical transmitter composed of a first optical phased array and transmitting diffracted light generated by light output from a plurality of first antenna elements constituting the first optical phased array to space.
An optical receiver composed of a second optical phased array and receiving light coming from the space by a plurality of second antenna elements constituting the second optical phased array.
With
The optical receiver has a plurality of maximum sensitivity directions in which the reception sensitivity of the light is maximized with respect to the direction of the light arriving from the space.
The first angle formed by the directions of the adjacent diffracted light transmitted by the optical transmitter to the space and the second angle formed by the adjacent maximum sensitivity directions in the optical receiver are different from each other. And
The optical receiver receives light coming from the space through the second optical component by the plurality of second antenna elements.
The second angle is defined as an angle formed by the adjacent maximal sensitivity directions defined in the space for light arriving from the space received via the second optical component.
The optical system composed of the second optical component reduces the arrangement pitch of the second antenna element as seen from the optical input side of the optical system with respect to the actual arrangement pitch of the second antenna element. Or to expand,
Rider device.

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