A multi-beam coherent detection lidar

Abstract

The application discloses a kind of multi-beam coherent detection laser radars, including seed light laser, first multi-channel fiber beam splitter, acoustooptic modulator, first pulse fiber amplifier, second multi-channel fiber beam splitter, second pulse fiber amplifier, circulator, multi-beam transceiver telescope, fiber combiner, balanced detector and multi-channel analog acquisition card;The application adopts large field of view multi-line laser output, can simultaneously detect the target distance, elevation, azimuth, speed and wind field of N field of view;Laser multi-line output with large field of view angle, while ensuring the detection distance, increases the detection field of view angle range;With horizontal scanning device, high-speed three-dimensional space wind field and target detection can be realized;The method of driving N laser amplifiers by a single seed light laser saves the cost of multiple seed light lasers.

Description

Technical Field

[0001] This invention relates to the field of lidar technology, and in particular to a multi-beam coherent detection lidar. Background Technology

[0002] Lidar, with its advantages of good directionality, high temporal and spatial resolution, high precision, and non-contact (remote sensing) detection, has been applied in fields such as velocity measurement, imaging, pollutant monitoring, wind measurement, temperature measurement, and density detection. Coherent lidar employs heterodyne detection, where the backscattered signal is amplified by the local oscillator, theoretically achieving a signal-to-noise ratio that can reach the quantum limit. Coherent lidar requires wavefront matching between the local oscillator and the signal light; therefore, it can suppress background noise and detector noise, enabling continuous observation without filters. Compared to direct wind lidar, coherent lidar does not require an optical discriminator, has a simpler receiving optical path, and is insensitive to temperature and stress gradients.

[0003] Coherent Doppler lidar research has been widely conducted both domestically and internationally. Lockheed Martin and Coherent Technologies Corp. (LMCT) are representative companies that have been dedicated to the research of coherent Doppler wind lidar. In 2002, LMCT released the WindTracer commercial coherent Doppler wind lidar system based on a 2μm laser. Currently, WindTracer has been upgraded to be based on a 1.617μm Er:YAG laser. NASA has used the commercial WindTracer system to detect aircraft wind shear and clear-air turbulence, and in 2009, it modeled and predicted aircraft eddies at Denver International Airport. In 2012, Mitsubishi Electric Corporation of Japan used Er,Yb:Glass planar waveguide technology and two-stage laser amplification technology to amplify the output power of the emitted laser, achieving horizontal wind field detection exceeding 30km. In 2015, ONERA achieved wind field detection at a range of 16 km by increasing the laser pulse energy of a fiber laser to 500 μJ through the parallel connection of multiple fiber amplifiers.

[0004] Domestically, in 2011, Zhou Dingfu's research group at the Southwest Institute of Technical Physics (SITP) (Institute 209) reported a 1.55μm all-fiber coherent Doppler wind lidar system, achieving wind field measurement within a height range of 5m to 200m, and comparing it with data from wind measurement towers at the experimental base. In 2017, Xia Haiyun's research group at the University of Science and Technology of China successfully developed the world's first coherent Doppler wind lidar capable of simultaneously observing atmospheric depolarization ratio and atmospheric wind field.

[0005] However, current commercially available Doppler lidar still has many shortcomings, such as a small field of view, inability to detect three-dimensional wind fields, and inability to detect targets. To address the challenges of detecting rapidly changing atmospheric wind fields and high-speed targets, there is a need for a coherent lidar capable of simultaneously detecting both wind fields and targets with a large field of view. Summary of the Invention

[0006] The purpose of this invention is to provide a multi-beam coherent detection lidar to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A multi-beam coherent detection lidar includes a seed laser, a first multi-channel fiber optic beam splitter, an acousto-optic modulator, a first pulse fiber optic amplifier, a second multi-channel fiber optic beam splitter, a second pulse fiber optic amplifier, a circulator, a multi-beam transceiver telescope, a fiber optic combiner, a balanced detector, and a multi-channel analog acquisition card. The source point of the seed laser is connected to the input end of the first multi-channel fiber optic beam splitter via an optical fiber. The output end of the first multi-channel fiber optic beam splitter is connected to the input end of the acousto-optic modulator and the input end of the fiber optic combiner, respectively. The signal output end of the acousto-optic modulator is connected to the signal input end of the first pulse fiber optic amplifier via an optical fiber. The signal output of the amplifier is connected to the signal input port of the second multi-channel fiber optic beam splitter via optical fiber. The output port of the multi-channel fiber optic beam splitter is connected to the input ports of N second pulse fiber optic amplifiers via optical fiber. The output ports of the N second pulse fiber optic amplifiers are respectively connected to the first ports of N circulators via optical fibers. The second ports of the N circulators are connected to a multi-beam transceiver telescope via optical fibers. The third ports of the N circulators are connected to the input port of a fiber optic combiner via optical fibers. The output port of the fiber optic combiner is connected to the input of a balanced detector via optical fibers. The output of the balanced detector is connected to a multi-channel analog acquisition card via an electrical signal.

[0009] Preferably, the multibeam transceiver telescope forms a fan-shaped spatial laser linear array.

[0010] Preferably, the modulation result of the acousto-optic modulator is pulsed light.

[0011] Preferably, the wavelength output by the seed laser can be ultraviolet light, visible light, or infrared light.

[0012] Preferably, the optical fiber coupled to the multi-beam transceiver telescope is a multimode optical fiber.

[0013] The workflow of a multi-beam coherent detection lidar device includes the following steps:

[0014] Step 1: Generate single-mode narrow-linewidth frequency-stable continuous light using a seed laser;

[0015] Step 2: The single-mode narrow-linewidth frequency-stabilized continuous light is evenly split into 1+N beams of equal power narrow-linewidth frequency-stabilized continuous light using the first multi-channel fiber optic beam splitter.

[0016] Step 3: The narrow-linewidth frequency-stabilized continuous light beam after being split evenly by the first multi-channel beam splitter enters the acousto-optic modulator C and is modulated by the acousto-optic modulator to obtain pulsed light;

[0017] Step 4: The pulsed light is guided through an optical fiber to a first pulse fiber amplifier, where it is amplified to obtain the first power-amplified pulsed light.

[0018] Step 5: The first power-amplified pulse light is evenly split by the second multi-channel fiber optic beam splitter to obtain N pulse lights with equal power;

[0019] Step 6: N pulses of equal power flow independently to their respective second pulse fiber amplifiers. The second pulse fiber amplifiers amplify the split pulses flowing into the amplifiers again to obtain a second power-amplified pulse.

[0020] Step 7: The N-strand second power amplified pulse light is guided into the corresponding circulator through optical fiber, and the circulator performs unidirectional isolation of the second power amplified pulse light;

[0021] Step 8: The second port of the circulator guides the second power-amplified pulse light through the optical fiber to the multi-beam transceiver telescope, and then the multi-beam transceiver telescope transmits the second power-amplified pulse light array and receives the reflected pulse light.

[0022] Step 9: The reflected pulsed light is fed back to the circulator through the multimode fiber, and then exported through the third port of the circulator to obtain the feedback pulsed light;

[0023] Step 10: The feedback pulse light enters the fiber optic combiner through the optical fiber, while the N narrow-linewidth frequency-stabilized continuous light beams after being split by the first multi-channel fiber optic splitter in step 2 are introduced into the fiber optic combiner through the optical fiber.

[0024] Step 11: The fiber optic combiner interferes with the feedback pulse light and the narrow linewidth frequency-stabilized continuous light, and then guides the resulting combined interference light to the balanced detector.

[0025] Step 12: The balanced detector detects the combined interference light to obtain the pulse electrical signal;

[0026] Step 13: The balanced detector imports the pulse electrical signal into the multi-channel analog acquisition card for signal data acquisition.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. This invention uses a large field of view multi-line laser output, which can simultaneously detect the target distance, elevation angle, azimuth, speed and wind field in N fields of view;

[0029] 2. This invention employs a wide field-of-view laser multi-line output, which increases the detection field of view range while ensuring the detection distance;

[0030] 3. When combined with a horizontal scanning device, this invention can achieve high-speed three-dimensional spatial wind field and target detection;

[0031] 4. The present invention uses a single seed laser to drive N laser amplifiers, which saves the cost of multiple seed lasers.

[0032] Instruction manual illustrations

[0033] Figure 1 This is a system structure diagram of the present invention.

[0034] In the diagram: Seed laser - A, First multi-channel fiber optic beam splitter - B, Acousto-optic modulator - C, First pulse fiber optic amplifier - D, Second multi-channel fiber optic beam splitter - E, Second pulse fiber optic amplifier - F, Circulator - G, Multi-beam transceiver telescope - H, Fiber optic combiner - I, Balanced detector - J, Multi-channel analog acquisition card - K. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example

[0037] Please see Figure 1This invention provides a technical solution: a multi-beam coherent detection lidar, comprising a seed laser A, a first multi-channel fiber optic beam splitter B, an acousto-optic modulator C, a first pulse fiber optic amplifier D, a second multi-channel fiber optic beam splitter E, a second pulse fiber optic amplifier F, a circulator G, a multi-beam transceiver telescope H, a fiber optic combiner I, a balanced detector J, and a multi-channel analog acquisition card K. The light source point of the seed laser A is connected to the input end of the first multi-channel fiber optic beam splitter B via optical fiber. The output end of the first multi-channel fiber optic beam splitter B is connected to the input end of the acousto-optic modulator C and the input end of the fiber optic combiner I, respectively. The signal output end of the acousto-optic modulator C is connected to the signal input end of the first pulse fiber optic amplifier D via optical fiber. The signal output of the first pulse fiber amplifier D is connected to the signal input port of the second multi-channel fiber beam splitter E via optical fiber. The output port of the multi-channel fiber beam splitter E is connected to the input ports of N second pulse fiber amplifiers F via optical fiber. The output ports of the N second pulse fiber amplifiers F are respectively connected to the first ports of N circulators G via optical fiber. The second ports of the N circulators G are connected to the multi-beam transceiver telescope H via optical fiber. The third ports of the N circulators G are connected to the input port of fiber beam combiner I via optical fiber. The output port of fiber beam combiner I is connected to the input of the balanced detector J via optical fiber. The output of the balanced detector J is connected to the multi-channel analog acquisition card K via an electrical signal.

[0038] Specifically, the multi-beam transceiver telescope H forms a fan-shaped spatial laser linear array.

[0039] Specifically, the modulation result of the acousto-optic modulator C is pulsed light, and in this embodiment, it is modulated as coded quasi-continuous pulsed light.

[0040] Specifically, the wavelength output by the seed laser A can be ultraviolet light, visible light, or infrared light.

[0041] Specifically, the optical fiber coupled to the multi-beam transceiver telescope H is a multimode optical fiber.

[0042] The workflow of a multi-beam coherent detection lidar device includes the following steps:

[0043] Step 1: Generate single-mode narrow-linewidth frequency-stable continuous light using seed laser A;

[0044] Step 2: The single-mode narrow-linewidth frequency-stabilized continuous light is evenly split into 1+N beams of equal power narrow-linewidth frequency-stabilized continuous light using the first multi-channel fiber beam splitter B.

[0045] Step 3: The narrow-linewidth frequency-stabilized continuous light beam after being split evenly by the first multi-channel beam splitter B enters the acousto-optic modulator C and is modulated by the acousto-optic modulator C to obtain pulsed light;

[0046] Step 4: The pulsed light is guided through the optical fiber to the first pulse fiber amplifier D, and the power is amplified by the first pulse fiber amplifier D to obtain the first power-amplified pulsed light;

[0047] Step 5: The first power-amplified pulse light is evenly split by the second multi-channel fiber beam splitter E to obtain N pulse lights with equal power;

[0048] Step 6: N pulses of equal power flow independently to their respective second pulse fiber amplifiers F. The second pulse fiber amplifiers F amplify the split pulses flowing into the amplifiers again to obtain a second power-amplified pulse.

[0049] Step 7: The N-strand second power amplified pulse light is introduced into the corresponding circulator G through the optical fiber, and the circulator G performs unidirectional isolation on the second power amplified pulse light;

[0050] Step 8: The second port of the circulator G guides the second power amplified pulse light through the optical fiber to the multi-beam transceiver telescope H, and then the multi-beam transceiver telescope H transmits the second power amplified pulse light array and receives the reflected pulse light.

[0051] Step 9: The reflected pulse light is fed back to the circulator G through the multimode fiber, and then exported through the third port of the circulator G to obtain the feedback pulse light.

[0052] Step 10: The feedback pulse light enters the fiber optic combiner I through the optical fiber, and at the same time, the N narrow-linewidth frequency-stabilized continuous light beams after being evenly split by the first multi-channel fiber optic splitter B in step 2 are introduced into the fiber optic combiner I through the optical fiber.

[0053] Step 11: Fiber optic combiner I interferes with the feedback pulse light and the narrow linewidth frequency-stabilized continuous light, and then guides the resulting combined interference light to the balanced detector J.

[0054] Step 12: The balanced detector J detects the combined interference light to obtain the pulse electrical signal;

[0055] Step 13: The balanced detector J imports the pulse electrical signal into the multi-channel analog acquisition card K for signal data acquisition.

[0056] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0057] All standard parts used in this invention can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art, and the circuit connection adopts conventional connection methods in the prior art, which will not be described in detail here.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-beam coherent detection lidar, comprising a seed laser A, a first multi-channel fiber optic beam splitter B, an acousto-optic modulator C, a first pulse fiber optic amplifier D, a second multi-channel fiber optic beam splitter E, a second pulse fiber optic amplifier F, a circulator G, a multi-beam transceiver telescope H, a fiber optic combiner I, a balanced detector J, and a multi-channel analog acquisition card K, characterized in that: The light source point of the seed laser A is connected to the input end of the first multi-channel fiber optic beam splitter B via optical fiber. The output end of the first multi-channel fiber optic beam splitter B is connected to the input end of the acousto-optic modulator C and the input end of the fiber optic combiner I, respectively. The signal output end of the acousto-optic modulator C is connected to the signal input end of the first pulse fiber optic amplifier D via optical fiber. The signal output end of the first pulse fiber optic amplifier D is connected to the signal input port of the second multi-channel fiber optic beam splitter E via optical fiber. The output port of the multi-channel fiber optic beam splitter E is connected to the input ports of N second pulse fiber optic amplifiers F via optical fiber. The output ports of the N second pulse fiber optic amplifiers F are respectively connected to the first ports of N circulators G via optical fiber. The second ports of the N circulators G are connected to the multi-beam transceiver telescope H via optical fiber. The third ports of the N circulators G are connected to the input port of the fiber optic combiner I via optical fiber. The output port of the fiber optic combiner I is connected to the input end of the balanced detector J via optical fiber. The output end of the balanced detector J is connected to the multi-channel analog acquisition card K via an electrical signal. The multibeam transceiver telescope H is configured to form a fan-shaped spatial laser linear array; The modulation result of the acousto-optic modulator C is pulsed light; The wavelength output by the seed laser A can be ultraviolet light, visible light, or infrared light; The optical fiber coupled to the multibeam transceiver telescope H is a multimode optical fiber; The workflow of the multi-beam coherent detection lidar includes the following steps: Step 1: Generate single-mode narrow-linewidth frequency-stable continuous light using seed laser A; Step 2: The single-mode narrow-linewidth frequency-stabilized continuous light is evenly split into 1+N beams of equal power narrow-linewidth frequency-stabilized continuous light using the first multi-channel fiber beam splitter B. Step 3: The narrow-linewidth frequency-stabilized continuous light beam after being split evenly by the first multi-channel beam splitter B enters the acousto-optic modulator C and is modulated by the acousto-optic modulator C to obtain pulsed light; Step 4: The pulsed light is guided through the optical fiber to the first pulse fiber amplifier D, and the power is amplified by the first pulse fiber amplifier D to obtain the first power-amplified pulsed light; Step 5: The first power-amplified pulse light is evenly split by the second multi-channel fiber beam splitter E to obtain N pulse lights with equal power; Step 6: N pulses of equal power flow independently to their respective second pulse fiber amplifiers F. The second pulse fiber amplifiers F amplify the split pulses flowing into the amplifiers again to obtain a second power-amplified pulse. Step 7: The N-strand second power amplified pulse light is introduced into the corresponding circulator G through the optical fiber, and the circulator G performs unidirectional isolation on the second power amplified pulse light; Step 8: The second port of the circulator G guides the second power amplified pulse light through the optical fiber to the multi-beam transceiver telescope H, and then the multi-beam transceiver telescope H transmits the second power amplified pulse light array and receives the reflected pulse light. Step 9: The reflected pulse light is fed back to the circulator G through the multimode fiber, and then exported through the third port of the circulator G to obtain the feedback pulse light. Step 10: The feedback pulse light enters the fiber optic combiner I through the optical fiber, and at the same time, the N narrow-linewidth frequency-stabilized continuous light beams after being evenly split by the first multi-channel fiber optic splitter B in step 2 are introduced into the fiber optic combiner I through the optical fiber. Step 11: Fiber optic combiner I interferes with the feedback pulse light and the narrow linewidth frequency-stabilized continuous light, and then guides the resulting combined interference light to the balanced detector J. Step 12: The balanced detector J detects the combined interference light to obtain the pulse electrical signal; Step 13: The balanced detector J imports the pulse electrical signal into the multi-channel analog acquisition card K for signal data acquisition.

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