Vehicle gauge level fiber laser radar high extinction ratio modulation light source and high isolation transceiver light path device

Abstract

The invention discloses a vehicle gauge level fiber laser radar high extinction ratio modulation light source and high isolation transmit-receive light path device, which adopts a mode of combining laser direct modulation and clock synchronization accurate delay trigger control external modulation, and improves the pulse modulation extinction ratio of traditional direct modulation by 70dB. The problem of optical signal interference of a detection channel caused by low pulse modulation extinction ratio of the laser is greatly reduced; the acousto-optic modulator synchronously controlled by a clock is adopted on a receiving optical path to realize isolation of a receiving channel and a transmitting channel, the isolation degree of coupling interference from a transmitting light beam to a receiving light beam is improved by 70dB, the problem of close-range blind area interference during laser signal detection is solved, and the close-range blind area range of a laser detection system is greatly reduced. In vehicle-gauge-level laser radar application, the problems of target light beam transmitting and receiving matching in a wide detection range and reduction of laser radar detection blind areas can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of lidar, and in particular to a vehicle-grade fiber optic lidar high extinction ratio modulation light source and a high isolation light emitting and receiving optical path device. Background Art

[0002] Currently, traditional vehicle-grade lidars adopt a light emitting and receiving separated optical path design mode in optical path transmission and reception. However, with the continuous increase in the demand for detection distance, in order to ensure the detection ability at a long distance, the transmitting field of view and the receiving field of view of lidars adopting the separated light emitting and receiving mode need to be matched to a relatively long distance, resulting in a large blind area at a short distance, and affecting the safety guarantee of the vehicle-mounted platform at a short distance.

[0003] Adopting a combined light emitting and receiving optical path design mode can effectively solve the problem of simultaneous matching of the transmitting and receiving fields of view at both near and far distances. However, in traditional combined light emitting and receiving optical paths, especially in the all-fiber mode of the combined light emitting and receiving optical path, there are problems of low extinction ratio of the light pulse modulation of the laser emission light source and low isolation degree of the light emitting and receiving optical paths, resulting in the coupling of the emission optical path to the reception optical path, causing interference in the reception channel, and even affecting the detection of the entire lidar. Summary of the Invention

[0004] The purpose of the present invention is to provide a vehicle-grade fiber optic lidar high extinction ratio modulation light source and a high isolation light emitting and receiving optical path device, which can solve the problem of optical signal interference in the combined optical path design mode of all-fiber lidars. To solve the problem of optical signal interference in the combined optical path design mode of all-fiber lidars, the present invention proposes a vehicle-grade fiber optic lidar high extinction ratio modulation light source and a high isolation light emitting and receiving optical path device. This device not only has a high pulse modulation extinction ratio but also has a high isolation degree between light emission and reception, which can greatly reduce the coupling leakage of the emission signal to the reception optical path and the interference of the optical channel signal. Especially for high-sensitivity detection systems such as single-photon detection and coherent detection, the isolation effect is more obvious.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A vehicle-grade fiber optic lidar high extinction ratio modulation light source and a high isolation light emitting and receiving optical path device, comprising a clock synchronization modulator, a fiber laser, a first acousto-optic modulator, a fiber optic circulator, an optical antenna, and a second acousto-optic modulator;

[0007] The clock synchronization modulator is used to generate three-way synchronous modulation signals. The first synchronous signal is used to synchronously modulate the fiber laser to generate a narrow pulse optical signal, realizing the function of generating the optical signal required for optical path detection. The second synchronous signal is used to synchronously modulate the first acousto-optic modulator to further isolate the pulse signal generated by the fiber laser. The third synchronous signal is used to synchronously modulate the second acousto-optic modulator to isolate the coupling interference signal from the transmitting optical path to the backscattered optical path.

[0008] The fiber laser is used to generate a narrow pulse optical signal under the synchronous trigger of the clock synchronization modulator for target signal detection.

[0009] The first acousto-optic modulator is used to isolate the pulse modulation interference signal in time for the narrow pulse optical signal generated by the fiber laser under the control of the clock synchronization modulator.

[0010] The fiber optic circulator is used to transmit the laser isolated by the first acousto-optic modulator to the optical antenna, and at the same time spatially separate the optical signal collected by the optical antenna from the transmitted laser signal. The optical antenna is used to collimate the narrow pulse optical signal generated by the fiber laser and irradiate it towards the target, and at the same time receive the echo signal scattered from the target.

[0011] The second acousto-optic modulator is used to isolate the coupling optical interference of the fiber laser into the receiving channel during optical pulse emission.

[0012] The clock synchronization modulator specifically includes: a clock chip with a 40MHz crystal oscillator, an FPGA of the xc7vx485tffg1927 chip, and 3-way SN74LVC2T45 TTL interface circuits. The clock chip with a 40MHz crystal oscillator is used to provide a clock signal for the FPGA of the xc7vx485tffg1927 chip to realize the generation and control of signals with different frequencies. The FPGA of the xc7vx485tffg1927 chip generates 3-way synchronous trigger logic signals under the clock signal of the clock chip with a 40MHz crystal oscillator. The 3-way SN74LVC2T45 TTL converts the synchronous trigger logic signals generated by the FPGA of the xc7vx485tffg1927 chip into TTL level signals for signal modulation and isolation.

[0013] The clock synchronization modulator controls the synchronization of the fiber laser, the first acousto-optic modulator, and the second acousto-optic modulator; the synchronization signal input to the fiber laser is a positive pulse with a pulse width of τ1 and a repetition frequency of f; the synchronization signal input to the first acousto-optic driver 1 is a positive pulse with a pulse width of τ2 and a repetition frequency of f; the synchronization signal input to the second acousto-optic driver 2 is a positive pulse with a pulse width of τ3 and a repetition frequency of f;

[0014] The emission time of the fiber laser is:

[0015] T 激光 =T 延迟时间 +T 响应时间

[0016] T 延迟时间 T is the transmission time from the start of synchronization signal generation to the input to the fiber laser. 延迟时间 Between 1ns and 20ns, T 响应时间 Related to the design of fiber laser, T 响应时间 20ns~300ns;

[0017] The working start time of the first acousto-optic modulator 1 is

[0018] T 第一调制 =T 延迟时间1 +T 响应时间1

[0019] T 延迟时间1 Set a fixed delay time, T, for the transmission time from the start of synchronization signal generation to the input to the first AOM. 延迟时间1 Between 1ns and 1000ns, T 响应时间1 Related to the design of the AOM, T 响应时间1 20ns~50ns;

[0020] The working start time of the second acousto-optic modulator 2 is:

[0021] T 第二调制 =T 延迟时间2 +T 响应时间2

[0022] T 延迟时间2 Set a fixed delay time, T, for the transmission time from the start of synchronization signal generation to the input to the second AOM. 延迟时间2 Usually in 1ns~1000ns, T 响应时间2 Related to the design of the AOM, T 响应时间2 20ns~50ns;

[0023] During normal operation, the timing relationship between the fiber laser, the first acousto-optic modulator 1, and the second acousto-optic modulator 2 is as follows:

[0024] T 第一调制 = T 激光 -τ2 / 2

[0025] T 第二调制 = T 激光 +τ1 + 2R 盲区 / c

[0026] wherein, R 盲区 is the blind area distance of the lidar, and c is the speed of light; the synchronization signal pulse width τ3 of the second acousto-optic driver is related to T 第二调制 and the repetition frequency f, and the typical width is 2000 ns to 3800 ns.

[0027] The first acousto-optic modulator and the second acousto-optic modulator both include: an acousto-optic modulation crystal

[0028] and an acousto-optic driver;

[0029] The acousto-optic modulation crystal is used to generate a pulse modulation signal under the drive of the acousto-optic driver, and realize the light-on state within the pulse width modulation time; and realize the light-off state outside the pulse width modulation time.

[0030] The acousto-optic modulation crystal of the first acousto-optic modulator is composed of an acousto-optic crystal with a +50 MHz frequency shift and a modulation extinction ratio ≥ 70 dB; the acousto-optic modulation crystal of the second acousto-optic modulator is composed of an acousto-optic crystal with a -50 MHz frequency shift and a modulation extinction ratio ≥ 70 dB.

[0031] The fiber optic circulator adopts a single-mode fiber optic circulator with a transceiver isolation degree of more than 50 dB to realize the function of separating the transceiver of the transmitted optical signal and the received optical signal.

[0032] The optical antenna adopts an optical lens with an effective aperture of ￠20 mm to realize the collimation of the transmitted optical signal and the collection function of the target echo signal.

[0033] The fiber laser adopts an externally triggered input current modulation method to realize the output of a pulsed optical signal with a working wavelength of 1550 nm, a repetition frequency of 250 kHz, a pulse width of 2 ns, and a peak power of 100 W, so as to realize the lidar point cloud image with long distance, high resolution, and high data rate of the lidar.

[0034] The device of the present invention combines direct modulation and external modulation of a laser, improving the extinction ratio of optical pulses in traditional direct modulation by 70 dB, greatly reducing the problem of optical signal interference in the detection channel caused by the low extinction ratio of laser pulse modulation; an acousto-optic modulator controlled by clock synchronization is used on the receiving optical path to isolate the transmitted light beam, increasing the isolation degree of coupling interference from the transmitting optical path to the receiving optical path by 70 dB, effectively solving the problem of interference in the short-distance blind area during laser signal detection, greatly reducing the short-distance blind area range of the lidar, and solving the problems of target beam transceiver matching within a large detection dynamic range and reducing the detection blind area of the lidar in automotive-grade lidar applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0036] Figure 1 It is a schematic block diagram of the circuit principle of the present invention;

[0037] Figure 2 It is a schematic diagram of timing synchronization of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0039] As Figure 1 and 2 shown, the present invention is composed of a clock synchronization modulator 100, a fiber laser 200, a first acousto-optic modulator 1300, a fiber optic circulator 400, an optical antenna 500, and a second acousto-optic modulator 2600.

[0040] The clock synchronization modulator 100 is composed of a clock chip with a 40 MHz crystal oscillator, an FPGA of an xc7vx485tffg1927 chip, and a 3-way SN74LVC2T45 TTL interface circuit, which completes the generation of 3-way modulation signals, realizes the pulse modulation of the fiber laser 200, the pulse switch modulation of the first acousto-optic modulator 1300, and the pulse switch modulation of the second acousto-optic modulator 2600.

[0041] The fiber laser 200 is used to generate the pulsed laser emission signal for lidar, and realizes the function of irradiating the lidar light source with a wavelength of 1550 nm.

[0042] The first acousto-optic modulator 1300 consists of an acousto-optic modulation crystal 1310 with a frequency shift of +50 MHz and a modulation extinction ratio ≥ 70 dB, and a first acousto-optic driver 1320 with an external trigger input, and completes the isolation of the background interference light of the pulsed laser signal generated by the fiber laser 200.

[0043] The fiber optic circulator 400 is used to transmit the laser isolated by the first acousto-optic modulator 1300 to the optical antenna, and at the same time spatially separates the optical signal collected by the optical antenna from the isolated transmitted laser, realizing the function of separating the echo signal with a transceiver isolation of 50 dB.

[0044] The optical antenna 500 collimates the laser isolated by the first acousto-optic modulator 1300, and at the same time has the function of collecting the echo signal scattered from the target with an effective aperture of ￠20 mm, and couples the collected return light into the circulator fiber for target signal detection.

[0045] The second acousto-optic modulator 2600 consists of an acousto-optic modulation crystal 2610 with a frequency shift of -50 MHz and a modulation extinction ratio ≥ 70 dB, and a second acousto-optic driver 2620 with an external trigger input, and completes the gating control function of the optical signal input to the circulator.

[0046] The working process is as follows: After the vehicle-grade fiber laser radar with a high extinction ratio modulation light source and a high isolation light emitting and receiving optical path device is powered on, the clock synchronization modulator 100 generates a modulation signal to modulate the fiber laser 200, generating a pulsed laser output and inputting it into the first acousto-optic modulator 1300; under the pulsed switch modulation generated by the clock synchronization modulator 100, the first acousto-optic driver 1320 is triggered to generate a pulsed drive signal, and the generated pulsed drive signal drives the acousto-optic modulation crystal 1310 to work. During the pulse width time when the acousto-optic modulation crystal 1310 is driven to work, the pulsed laser signal generated by the fiber laser 200 can pass through the acousto-optic modulation crystal 1310, while when it is outside the pulse width time when the acousto-optic modulation crystal 1310 works, the transmitted signal will be blocked from passing through; the passed laser pulse signal is input into the fiber optic circulator 400, and after passing through the optical antenna 500, it is transmitted to the target; the echo signal scattered from the target passes through the optical antenna 500 again, is input into the fiber optic circulator 400, and is input from the return end of the fiber optic circulator 400 into the acousto-optic modulation crystal 2610 of the second acousto-optic modulator 2600; the pulsed switch modulation generated by the clock synchronization modulator 100 is input into the second acousto-optic driver 2620, triggering the second acousto-optic driver 2620 to generate a pulsed drive signal, and the generated pulsed drive signal drives the acousto-optic modulation crystal 2610 to work. During the pulse width time when the acousto-optic modulation crystal 2610 is driven to work, the optical signal input from the circulator can pass through the acousto-optic modulation crystal 2610, while when it is outside the pulse width time when the acousto-optic modulation crystal 2610 works, the input signal will be blocked from passing through; the optical signal passing through the acousto-optic modulation crystal 2610 will be sent to the detector for detecting the echo signal.

[0047] See Figure 2 , the clock synchronization modulator 100 proposed by this invention generates 3-way modulation signals. The synchronization signal input to the fiber laser 200 is a positive pulse with a pulse width of τ1 and a repetition frequency of f; the synchronization signal input to the first acousto-optic driver 1320 is a positive pulse with a pulse width of τ2 and a repetition frequency of f; the synchronization signal input to the second acousto-optic driver 2620 is a positive pulse with a pulse width of τ3 and a repetition frequency of f.

[0048] The light output time of the fiber laser 200 is

[0049] T 激光 = T 延迟时间 + T 响应时间

[0050] The T delay time is the transmission time from the start of the generation of the synchronization signal to the input to the fiber laser 200. T 延迟时间 is usually between 1 ns and 20 ns. T 响应时间 is related to the design of the fiber laser. T 响应时间It ranges from 20 ns to 300 ns.

[0051] The working start time of the first acousto-optic modulator 1300 is

[0052] T 第一调制 = T 延迟时间1 + T 响应时间1

[0053] T delay time 1 is the transmission time from the start of the generation of the synchronization signal to the input to the first acousto-optic modulator 1300 and the set fixed delay time, T 延迟时间1 usually ranges from 1 ns to 1000 ns, T 响应时间1 is related to the design of the acousto-optic modulator, T 响应时间1 It ranges from 20 ns to 50 ns.

[0054] The working start time of the second acousto-optic modulator 2600 is

[0055] T 第二调制 = T 延迟时间2 + T 响应时间2

[0056] T 延迟时间2 is the transmission time from the start of the generation of the synchronization signal to the input to the second acousto-optic modulator 2600 and the set fixed delay time, T 延迟时间2 usually ranges from 1 ns to 1000 ns, T 响应时间2 is related to the design of the acousto-optic modulator, T 响应时间2 It ranges from 20 ns to 50 ns.

[0057] During normal operation,

[0058] T 第一调制 = T 激光 - τ2 / 2

[0059] T 第二调制 = T 激光 + τ1 + 2R 盲区 / c

[0060] where R blind spot is the blind spot distance of the lidar, c is the speed of light, taking 3 × 10^8 m / s. The synchronization signal pulse width τ3 of the second acousto-optic driver 2620 is usually related to T 第二调制 and the repetition frequency f.

[0061] Typical embodiments are as follows:

[0062] The clock synchronization modulator 100 generates three modulated signals. The synchronization signal input to the fiber laser 200 is a positive pulse with a pulse width of 2 ns and a repetition frequency of 250 kHz. The synchronization signal input to the first acousto-optic driver 1320 is a positive pulse with a pulse width of 60 ns and a repetition frequency of 250 kHz. The synchronization signal input to the second acousto-optic driver 2620 is a positive pulse with a pulse width of 3500 ns and a repetition frequency of 250 kHz, and there is a 65-ns time delay relative to the light output time of the fiber laser 200. The time delay of the synchronization signal input to the second acousto-optic driver 2620 relative to the synchronization signal input to the fiber laser 200 is within the coupling interference section from the transmitting channel to the receiving channel. At this time, the second acousto-optic driver 2620 is exactly in the signal-off state section, and the interference signal cannot enter the receiving channel and be input to the detector, thus no interference can be formed. Since the optical signal between the transmitted beam and the detection passes through the first acousto-optic modulator 1300 and the second acousto-optic modulator 2600, the extinction ratio of the optical pulse modulation is increased by 70 dB, and the transmit-receive isolation is increased by ≥70 dB.

[0063] In summary, for a vehicle-grade fiber lidar high-extinction-ratio modulation light source and high-isolation transmit-receive optical path device of the present invention, a technical solution combining direct modulation of the laser and precise delay trigger control of clock synchronization is adopted. The extinction ratio of the optical pulse modulation of the traditional direct modulation is increased by 70 dB, greatly reducing the problem of optical signal interference in the detection channel caused by the low extinction ratio of the laser pulse modulation. An acousto-optic modulator controlled by clock synchronization is used on the receiving optical path to isolate the transmitted beam, increasing the coupling interference isolation from the transmitting optical path to the receiving optical path by 70 dB, effectively solving the problem of interference in the short-distance blind area during laser signal detection, greatly reducing the short-distance blind area range of the lidar, and solving the problems of target beam transmit-receive matching within a large detection dynamic range and reducing the detection blind area of the lidar in the application of vehicle-grade lidar.

[0064] Compared with the traditional co-located optical path, for a vehicle-grade fiber lidar high-extinction-ratio modulation light source and high-isolation transmit-receive optical path device of the present invention, a technical solution combining direct modulation of the laser and precise delay trigger control of clock synchronization is adopted, greatly enhancing the extinction ratio of the pulsed laser modulation; a fiber optic circulator is used to realize the transmission of the transmit-receive optical path; an acousto-optic modulator controlled by clock synchronization is used on the receiving optical path to isolate the transmitted beam, reducing the coupling influence from the transmitting optical path to the receiving optical path.

[0065] This device combines direct modulation of the laser with external modulation, improving the extinction ratio of optical pulses in traditional direct modulation by 70 dB, greatly reducing the problem of optical signal interference in the detection channel caused by the low extinction ratio of laser pulse modulation; on the receiving optical path, an acousto-optic modulator controlled by clock synchronization is used to isolate the transmitted light beam, increasing the isolation degree of coupling interference from the transmitted optical path to the receiving optical path by 70 dB, effectively solving the problem of interference in the short-distance blind area during laser signal detection, greatly reducing the short-distance blind area range of the lidar, and solving the problems of target beam transceiver matching within a large detection dynamic range and reducing the detection blind area of the lidar in automotive-grade lidar applications.

[0066] In the description of the present invention, it should be noted that for orientation terms, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation and position relationship are based on the orientation or position relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of the present invention.

[0067] It should be noted that the terms "comprising" and "having" in the specification and claims of this application, and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that comprises a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products, or devices.

[0068] Note that the above is only the preferred embodiment of the present invention and the application of technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described here. Various obvious changes, re-adjustments, and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the specific embodiments described here. Without departing from the concept of the present invention, more other effective embodiments can also be included, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A vehicle - grade fiber - optic lidar high - extinction - ratio modulation light source and a high - isolation light - emitting and light - receiving optical path device, characterized in that: It includes a clock synchronization modulator, a fiber laser, a first acousto-optic modulator, an optical fiber circulator, an optical antenna, and a second acousto-optic modulator; The clock synchronization modulator is used to generate three-way synchronous modulation signals. The first-way synchronous signal is used to synchronously modulate the fiber laser to generate a narrow pulse optical signal, realizing the function of generating the optical signal required for optical path detection; The second-way synchronous signal is used to synchronously modulate the first acousto-optic modulator to further isolate the pulse signal generated by the fiber laser; The third-way synchronous signal is used to synchronously modulate the second acousto-optic modulator to isolate the coupling interference signal from the transmitting optical path to the backscattered optical path; The fiber laser is used to generate a narrow pulse optical signal under the synchronous trigger of the clock synchronization modulator for target signal detection; The first acousto-optic modulator is used to isolate the pulse modulation interference signal in time for the narrow pulse optical signal generated by the fiber laser under the control of the clock synchronization modulator; The optical fiber circulator is used to transmit the laser isolated by the first acousto-optic modulator to the optical antenna, and at the same time spatially separate the optical signal collected by the optical antenna from the transmitted laser signal; The optical antenna is used to collimate the narrow pulse optical signal generated by the fiber laser and irradiate it towards the target, and at the same time receive the echo signal scattered from the target; The second acousto-optic modulator is used to isolate the coupling optical interference of the fiber laser into the receiving channel during optical pulse emission.

2. The high extinction ratio modulation light source and high isolation light emitting and receiving optical path device for vehicle-grade fiber laser radar according to claim 1, characterized in that, The clock synchronization modulator specifically includes: a clock chip with a 40MHz crystal oscillator, an FPGA of an xc7vx485tffg1927 chip, and 3-way SN74LVC2T45 TTL interface circuits; the clock chip with a 40MHz crystal oscillator is used to provide a clock signal for the FPGA of the xc7vx485tffg1927 chip to realize the generation and control of different frequency signals; the FPGA of the xc7vx485tffg1927 chip generates 3-way synchronous trigger logic signals under the clock signal of the clock chip with a 40MHz crystal oscillator; the 3-way SN74LVC2T45 TTL converts the synchronous trigger logic signals generated by the FPGA of the xc7vx485tffg1927 chip into TTL level signals for signal modulation and isolation.

3. The high extinction ratio modulation light source and high isolation light emission and reception optical path device for vehicle-grade fiber laser radar according to claim 1, characterized in that, The clock synchronization modulator controls the synchronization of the fiber laser, the first acousto-optic modulator, and the second acousto-optic modulator; the synchronous signal input to the fiber laser is a positive pulse with a pulse width of τ1 and a repetition frequency of f; the synchronous signal input to the first acousto-optic driver is a positive pulse with a pulse width of τ2 and a repetition frequency of f; the synchronous signal input to the second acousto-optic driver is a positive pulse with a pulse width of τ3 and a repetition frequency of f; The light output time of the fiber laser is: T 激光 = T 延迟时间 + T 响应时间 T 延迟时间 is the transmission time from the start of the synchronization signal generation to its input into the fiber laser, T 延迟时间 is between 1 ns and 20 ns, T 响应时间 is related to the design of the fiber laser, T 响应时间 is between 20 ns and 300 ns; The start time of operation of the first acousto-optic modulator 1 is T 第一调制 = T 延迟时间1 + T 响应时间1 T 延迟时间1 For the transmission time from the start of the synchronization signal generation to the input to the first acousto-optic modulator and to set a fixed delay time, T 延迟时间1 is between 1 ns and 1000 ns, T 响应时间1 is related to the design of the acousto-optic modulator, T 响应时间1 is between 20 ns and 50 ns; The start time of operation of the second acousto-optic modulator 2 is: T 第二调制 = T 延迟时间2 + T 响应时间2 T 延迟时间2 To synchronize the transmission time from the start of the generation of the signal to its input into the second acousto-optic modulator and set a fixed delay time, T 延迟时间2 is usually in the range of 1 ns to 1000 ns, T 响应时间2 is related to the design of the acousto-optic modulator, T 响应时间2 and is in the range of 20 ns to 50 ns; During normal operation, the time relationship among the fiber laser, the first acousto-optic modulator 1, and the second acousto-optic modulator 2 is as follows: T 第一调制 = T 激光 -τ2 / 2 T 第二调制 = T 激光 + τ1 + 2R 盲区 / c wherein, R 盲区 is the blind zone distance of the lidar, c is the speed of light; the synchronization signal pulse width τ3 of the second acousto-optic driver is related to T 第二调制 and the repetition frequency f, and the typical width is 2000 ns to 3800 ns.

4. The high extinction ratio modulation light source and high isolation light emitting and receiving optical path device for vehicle-grade fiber laser radar according to claim 1, wherein, Both the first acousto-optic modulator and the second acousto-optic modulator include: an acousto-optic modulation crystal and an acousto-optic driver; The acousto-optic modulation crystal is used to generate a pulse modulation signal under the drive of the acousto-optic driver, and achieve the light-on state within the pulse width modulation time; and achieve the light-off state outside the pulse width modulation time.

5. The high extinction ratio modulation light source and high isolation light emitting and receiving optical path device for vehicle-mounted fiber laser radar according to claim 4, characterized in that, The acousto-optic modulation crystal of the first acousto-optic modulator is composed of an acousto-optic crystal with a +50 MHz frequency shift and a modulation extinction ratio ≥ 70 dB; the acousto-optic modulation crystal of the second acousto-optic modulator is composed of an acousto-optic crystal with a -50 MHz frequency shift and a modulation extinction ratio ≥ 70 dB.

6. The high extinction ratio modulation light source and high isolation light emitting and receiving optical path device for vehicle-grade fiber laser radar according to claim 1, characterized in that, The fiber optic circulator adopts a single-mode fiber optic circulator with a transceiver isolation degree of more than 50 dB to realize the function of separating the transceiver of the transmitted optical signal and the received optical signal.

7. The high extinction ratio modulation light source and high isolation light emitting and receiving optical path device for vehicle-grade fiber laser radar according to claim 1, characterized in that The optical antenna described above uses an effective-aperture optical lens to collimate the transmitted optical signal and collect the target echo signal.

8. A vehicle-grade fiber laser radar high extinction ratio modulation light source and high isolation light emitting and receiving optical path device according to claim 1, characterized in that, The fiber laser adopts an externally triggered input current modulation method to achieve the output of a pulsed optical signal with a working wavelength of 1550 nm, a repetition frequency of 250 kHz, a pulse width of 2 ns, and a peak power of 100 W, so as to realize the lidar point cloud image with long distance, high resolution, and high data rate.

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