CN109490865B

CN109490865B - Area array laser radar

Info

Publication number: CN109490865B
Application number: CN201811512676.3A
Authority: CN
Inventors: 姜波; 金元浩; 赵忠尧
Original assignee: Ruichi Zhiguang Beijing Technology Co ltd
Current assignee: Ruichi Zhiguang (Suzhou) Technology Co., Ltd
Priority date: 2018-12-11
Filing date: 2018-12-11
Publication date: 2021-03-05
Anticipated expiration: 2038-12-11
Also published as: CN112835016A; CN109490865A

Abstract

The invention discloses an area array laser radar, which comprises: the device comprises a laser array, a detector array, a laser light path adjusting device and a signal light path adjusting device. The laser array is arranged in a linear array, the laser array is arranged along a first direction, the laser light path adjusting device is a plurality of planar optical waveguide PLCs which are overlapped along the first direction, the laser light path adjusting device is arranged in front of the laser array, the detector array is arranged along a second direction, the signal light path adjusting device is a plurality of planar optical waveguide PLCs which are overlapped along the second direction, and the first direction and the second direction are perpendicular to each other.

Description

Area array laser radar

Technical Field

The invention relates to the field of optics, in particular to an area array laser radar.

Background

The laser radar is a radar system that detects a characteristic amount such as a position and a velocity of a target by emitting a laser beam. In terms of working principle, the radar antenna has no fundamental difference from microwave radar: the method comprises the steps of transmitting a detection signal (laser beam) to a target, comparing a received signal (target echo) reflected from the target with the transmitted signal, and after proper processing, obtaining relevant information of the target, such as target distance, azimuth, height, speed, attitude, even shape and other parameters, thereby detecting, tracking and identifying the target such as an airplane, a missile and the like.

Laser radars can be generally divided into two parts, laser ranging techniques and scanning techniques. The laser ranging technique mainly solves the problem of distance measurement, and the imaging technique mainly solves the problem of beam scanning. In a polar coordinate system, one point of a space can be uniquely determined by one distance and two angles, which is also the theoretical basis for realizing space three-dimensional scene depiction by all laser radars.

Currently, there are many records about lidar in the prior art, and there are many existing solutions for scanning lidar:

1. mechanical scanning

Mechanical scanning has various forms, such as one-dimensional or two-dimensional rotation of the whole ranging part to make the laser beam cover a certain range of space; or by directing the beam to a defined spatial region using one or more rotating or oscillating mirrors.

2. Electro-optical scanning and acousto-optical scanning

The optical deflection is achieved by using electro-optical or acousto-optical effects of the material.

3. Phased array

Spatial scanning of the beam is achieved by fine phase control of the wavefront of the beam using the huygens principle.

Mems scanning

Its essence is still a vibrating mirror, but the mirror size is small.

The existing methods have the defects that the mechanical scanning has a large-size rotating part, and the service life and the stability are easily influenced by external vibration. Electro-optic and acousto-optic scanning are adopted, a control circuit is complex, and the scanning angle is small. The phased array is difficult to produce and manufacture, small in deflection angle and provided with side lobes. Mems is similar to mechanical scanning, with small lens size and good mechanical properties, but still has rotating parts, which are still affected.

Disclosure of Invention

In view of the deficiencies of the prior art, it is desirable to provide an area array lidar configured to address at least one of the above-mentioned problems.

Specifically, the present invention provides an area array laser radar, including: the device comprises a laser array, a detector array, an optical lens, a laser light path adjusting device and a signal light path adjusting device.

Preferably, the laser array is a laser linear array, the laser linear array is arranged along a first direction, the laser optical path adjusting device is a plurality of one-to-many beam splitting channels stacked along the first direction, the laser optical path adjusting device is arranged in front of the laser array, the detector array is a detector linear array, the detector linear array is arranged along a second direction, the signal optical path adjusting device is a plurality of one-to-many beam splitting channels stacked along the second direction, the first direction and the second direction are perpendicular to each other, and the optical lens is arranged in front of the laser optical path adjusting device and the signal optical path adjusting device.

Preferably, the laser light path adjusting device is a plurality of planar optical waveguides PLC stacked in a first direction with each other, and the signal light path adjusting device is a plurality of planar optical waveguides PLC stacked in a second direction.

Preferably, the number of lasers in the laser array, the number of PLCs in the laser light path adjusting means, the number of detectors in the detector array, and the number of PLCs in the signal light path adjusting means are the same as each other.

Preferably, in the planar optical waveguide PLC of the laser optical path adjusting apparatus, input ports of a plurality of planar optical waveguide PLCs are arranged in a linear array, and each input port corresponds to each light outlet of the laser array; in the planar optical waveguide PLC of the signal light path adjusting device, output ports of a plurality of planar optical waveguide PLCs are arranged in a linear array, and each output port corresponds to a corresponding detector of the detector array.

Preferably, the area array laser radar further comprises a time sequence controller, wherein the time sequence controller controls each laser in the laser array to work in sequence, when any one laser works, the time sequence controller controls each detector in the detector array to start in sequence to complete one-dimensional scanning, and when all the lasers complete one round of work, one round of area array scanning is completed.

Preferably, the area array laser radar further comprises a timing controller, the timing controller controls all or part of the lasers in the laser array to work according to a preset sequence, and when any one of the lasers works, the timing controller controls all or part of the detectors in the detector array to start according to the preset sequence.

Principle of the invention

The applicant has noted during its development that an optical lens is capable of angularly mapping a spatial beam onto a focal plane. That means that the point that is moved in two dimensions in the focal plane in fact scans the ray angle. One obvious optical scanning method is the area array of detectors and lasers. The lasers and detectors are in one-to-one correspondence. Such production and manufacturing difficulties are very high. The state of the art is more difficult to achieve.

Knowing that a point on a plane is represented by a coordinate (x, y), an area array is in fact a walk through discretizing (x, y). This process is usually performed either in 2-dimensional traversal at the transmitting end, in traversal at the receiving end, or in both.

No matter which traversal mode is adopted, the transmitting end traverses, or a high-power laser is adopted, so that the human eyes are damaged, or an area array laser is adopted, the cost is high, the addressing is difficult, and n lasers are adopted, and the driving circuits are also n.

The receiving end is traversed, either a large view field is adopted, the noise is high, the detection distance is limited, or an area array detector is adopted, the number of the detectors is the same as that of pixels, the cost is high, the addressing is difficult, and the number of the amplifying circuits and the time measuring circuits is also n.

By adopting the structure of the invention, the x direction and the y direction can be traversed simultaneously, n lasers and n detectors are adopted, the circuit scale is changed from the quadratic power of n to the first power of n, the larger n is, the greater the advantage is, but n cannot be too large and too large, the power distribution is too small, and the measurement is still not far.

Technical effects

The invention introduces the light cube for the first time, and can quickly realize two-dimensional array scanning by only the selection control of electronic devices under the condition of not needing any moving parts by orthogonally arranging the detector array and the laser.

The invention adopts n lasers and n detectors, the circuit scale is changed from the quadratic power of n to the first power of n, the larger n is, the greater the advantage is, but n can not be too large, the power distribution is too small, and the measurement is still not far.

Preferably, N is 16 or 32, and in this case, an appropriate balance is achieved between resolution, circuit scale, measurement distance, and measurement speed. Low cost and good effect.

The laser radar can realize large-scale scanning without rotating parts, thereby solving the problems of service life and stability of mechanical scanning; the laser radar control circuit is simple, only the selective control starting of the detector in the corresponding light path can be realized, the difficulty of the laser radar production and manufacturing is far smaller than that of phased array equipment, the detection range is large, the detection range is only limited by the field angle of the optical lens, and side lobes are avoided.

Drawings

FIG. 1 is a simplified schematic diagram of a lidar in accordance with the present invention;

FIG. 2 is a schematic structural diagram of a plurality of Planar Lightwave Circuits (PLC) stacked in sequence;

FIG. 3 is a front, left and rear view of a light cube formed after stacking of 16 planar lightguides;

FIG. 4 is a schematic diagram of a detector array used in an embodiment of the present invention;

FIG. 5 is a schematic diagram of a laser array used in an embodiment of the present invention;

FIG. 6 is a schematic diagram of a combined detector array and light cube;

FIG. 7 is a schematic diagram of a combined laser array and light cube configuration;

FIG. 8 is a schematic diagram of an optical path structure of a planar lightwave circuit PLC employed in the present invention;

fig. 9 is a schematic diagram of a light beam incident on a focal plane when performing laser ranging.

Detailed Description

The invention is described in detail below with reference to the drawings and examples, but the scope of the invention is not limited to the examples.

Example 1

In this embodiment, as shown in fig. 1, the area array laser radar includes: a laser array 1, a detector array 2, a laser light path adjusting device 3, a signal light path adjusting device 4, and two optical lenses 5. The laser array adopts a linear array laser array, the laser array is arranged along the horizontal direction, the laser light path adjusting device is a plurality of planar optical waveguide PLC which are mutually overlapped along the horizontal direction, the laser light path adjusting device is arranged in front of the laser array, the detector array is arranged along the vertical direction, the signal light path adjusting device is a plurality of planar optical waveguide PLC which are mutually overlapped along the vertical direction, and the arrangement direction of the laser array is mutually vertical to the detector array.

In the embodiment, a plurality of planar optical waveguides PLC are stacked to form two light cubes respectively, wherein one light cube is used as a laser light path adjusting device 3, and the other light cube is used as a signal light path adjusting device 4 and is arranged in front of a laser array and a detector array respectively.

As shown in fig. 2, each light cube has 16 layers, and each layer of each light cube has 16 ports on one side, arranged laterally, and only one port on the other side, and the 16 ports on one side of each layer of the light cube can each communicate with a single port on the other side.

In this embodiment, the number of lasers in the laser array, the number of PLCs in both light cubes, and the number of detectors in the detector array are all 16.

For the light cube in front of the laser array, the planar optical waveguide PLC of each layer has one input and 16 outputs, and the input ports of the planar optical waveguide PLCs are arranged in a linear array, and each input port corresponds to each light outlet of the laser array.

For the light cube in front of the detector array, the planar optical waveguide PLC of each layer has 16 inputs and 1 output, the output ports of the planar optical waveguide PLCs are arranged in a linear array, and each output port corresponds to a signal detection area of the detector array. 16 inputs are input to each layer, and 16 layers in total are combined into a 16-by-16 area array.

Of course, it should be understood by those skilled in the art that although 16 × 16 area arrays are illustrated, those skilled in the art may employ other numbers of area arrays, such as 8 × 8, 64 × 64, etc., in light of the present inventive concept. Preferably, the number of one side of the area array is n-th power of 2, and n is a positive integer greater than or equal to 2.

When the area array laser radar is used, the two-dimensional traversal of the existing laser radar is separately carried out, the transmitting end carries out x traversal (in the vertical direction in the figure), and the receiving end carries out y traversal (in the horizontal direction in the figure). Since xy is orthogonal, the two are combined to just realize two-dimensional traversal.

The invention adopts a one-to-many planar optical waveguide PLC, which mainly has the functions of restraining light in a waveguide and distributing optical power, as shown in figure 8, the PLC is a 1: 16 PLC. The device can also be used in reverse to realize the beam combination function of light.

For example, light with power P is incident from port 0, optical power will be output from port 1-port 16, and the optical power output from each path will be P/16.

As another example, light incident from port 1-port 16 will be output from port 0 with a power that is the sum of the 16 port incident powers.

The structure of the light cube is shown in fig. 2-3, which is a cube structure formed by stacking 16 PLCs. One face of the cube is 16 x 16 ports, and the other face is 16 ports. The ports are numbered according to the following rules. Port address (PLC number, port number).

As shown in fig. 4, the detector array is formed by arranging 16 detectors in a linear array, and the period of the detector is the same as the period of the port of the PLC (the period refers to the spatial distance between the centers of two adjacent detectors).

As shown in fig. 5, the laser array is formed by arranging 16 lasers in a linear array, and the period of the lasers is the same as the port period of the PLC.

As shown in fig. 6, the DETECTOR array and the light cube are combined, with the DETECTOR1 aligned with the (row 1, port 0) port of the light cube and the DETECTOR 16 aligned with the (row 16, port 0) port of the light cube.

Thus, light incident from any port (row x, port y) of the light cube will be distributed by the light cube to the detector x corresponding to the row x.

As shown in fig. 7, which is a combined laser array and light cube configuration, LD1 is aligned with the (row 1, port 0) ports of the light cube and LD16 is aligned with the (row 16, port 0) ports of the light cube.

Thus, the light from the LDx laser will be evenly distributed to ports 1-16 of row x

Returning to fig. 1, the detector modules and the laser modules are arranged side by side, wherein the detector array is in the y direction, the laser array is in the x direction, and the two corresponding light cubes are also in an orthogonal state. The plane of the port array of the light cube is placed at the focal plane of the optical lens.

The method for realizing the optical scanning comprises the following steps:

the LD1 emits light, the emitted light is emitted from the port 1 to the port 16 of the row 1 of the light cube at the same time, after the light is irradiated to the object to be measured through the optical lens, the laser is reflected, is received by the port 1 of the row 1 to the port 16 of the light cube of the receiving module, and is further received by the detector1 to the detector 16 at the same time, at this time, the detector is selectively controlled through a circuit, and a signal is output from the detector 1. By sequentially selecting detectors by illuminating the LD1 16 times in succession, a one-dimensional scan of 16 points will be achieved. By analogy, continuing to illuminate LD2-LD16 will achieve another dimension of scanning. The device of the present invention can scan the area corresponding to the whole area array, and can also scan the area corresponding to a part of the area array according to the requirement, for example, a specific area within 4 × 4 of the area can be scanned or the area corresponding to a certain point can be detected.

By this means, without any moving parts, a 16 x 16 lattice scan in the focal plane of the lens, i.e. a spatial scan of the beam, can be achieved, simply by means of selective control of the circuit.

Then, the scanning ranging of the target can be realized by the existing ranging principle of laser ranging.

The distance measurement is carried out under a polar coordinate system, a space arbitrary point M is set, the coordinate of the space arbitrary point M in a rectangular coordinate system is (x, y, z), and the following ordered arrays are arranged

Spherical coordinates called point M: sitting positionThe index r is the distance of the point M from the origin,

is the angle formed by the half-plane passing through the z-axis and point M with the coordinate plane zOx; θ is the angle between the line OM and the positive direction of the z-axis, so the variation range of these coordinates in space is:

0≤r≤+∞；

0≤θ≤π

the present invention makes use of one principle of an ideal optical lens, i.e. for an ideal optical lens it has the function of mapping incident rays of different angles to different points on the focal plane. I.e. a coordinate-determined point (x, y) in the focal plane of the lens, corresponding to the polar coordinate system

Wherein r is an arbitrary value.

That is, with the area array scanning lidar of the present invention, the detection of the entire optical lens field of view can be achieved by disposing the light entrance (16 × 16 area array side) of the light cube corresponding to the detector on the focal plane of the optical lens. Of course, the light outlet of the light cube in front of the laser array is also arranged on the focal plane of the optical lens in front of the laser array, so that after the light emitted by the laser array is incident on the optical lens along the different light outlets of the light cube, the light can be emitted to different directions after being refracted by the optical lens, and further detection in a larger area is realized.

While the principles of the invention have been described in detail in connection with the preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing embodiments are merely illustrative of exemplary implementations of the invention and are not limiting of the scope of the invention. The details of the embodiments are not to be interpreted as limiting the scope of the invention, and any obvious changes, such as equivalent alterations, simple substitutions and the like, based on the technical solution of the invention, can be interpreted without departing from the spirit and scope of the invention.

Claims

1. An area array lidar, comprising: a laser array, a detector array, an optical lens, a laser light path adjusting device and a signal light path adjusting device,

the laser array is a laser linear array which is arranged along a first direction, the laser path adjusting device is a plurality of planar optical waveguides PLC with a pair of multi-beam splitting channels which are mutually overlapped along the first direction, the input ports of the plurality of planar optical waveguides PLC are arranged according to the linear array, the laser path adjusting device is arranged in front of the laser array,

the detector array is a detector linear array which is arranged along a second direction, the signal light path adjusting device is a plurality of planar optical waveguide PLCs with a plurality of one-to-many beam splitting channels which are mutually overlapped along the second direction, output ports of the plurality of planar optical waveguide PLCs are arranged according to the linear array, the signal light path adjusting device is arranged in front of the detector array,

the first direction and the second direction are perpendicular to each other,

the optical lens is arranged in front of the laser light path adjusting device and the signal light path adjusting device,

the input port of each beam splitting channel of the laser light path adjusting device corresponds to each light outlet of the laser array respectively; a plurality of output ports of each beam splitting channel of the laser light path adjusting device are arranged according to a linear array,

the output port of each beam splitting channel of the signal light path adjusting device corresponds to a corresponding detector of the detector array; a plurality of input ports of each beam splitting channel of the signal light optical path adjusting device are arranged in a linear array,

the number of lasers in the laser array, the number of beam splitting channels in the laser optical path adjusting device, the number of output ports of each beam splitting channel in the laser optical path adjusting device, the number of detectors in the detector array, the number of beam splitting channels in the signal light optical path adjusting device, and the number of input ports of each beam splitting channel in the signal light optical path adjusting device are the same as each other.

2. The area array lidar of claim 1, further comprising a timing controller, wherein the timing controller controls each laser in the laser array to operate sequentially, and when any one of the lasers operates, the timing controller controls each detector in the detector array to start sequentially to complete one-dimensional scanning, and when all the lasers complete one-round operation, one-round area array scanning is completed.

3. The area array lidar of claim 1, further comprising a timing controller that controls the lasers in the array to operate in a predetermined sequence, and when any one of the lasers is operating, the timing controller controls the detectors in the array to activate in the predetermined sequence.

4. The area array lidar of claim 1, wherein the laser path adjustment device is a plurality of one-to-many beam splitting channels.

5. A laser detection system employing the area array lidar as recited in any of claims 1-4.