A highly integrated vehicle-mounted laser radar system

Abstract

The present invention relates to a highly integrated vehicle-mounted laser radar system, which includes: a seed light source, an optical router device, a pump light source, an amplifying optical fiber, a partial reflector, a scanning system, a detector, and a signal processing device. The seed light source optical signal is input from the first port of the optical router device and output from the second port of the optical router device; the optical signal amplified by the amplifying optical fiber and the pump light source is output from the third port of the optical router; a small part of the optical signal is reflected by the partial reflector, and the reflected light beam is output from the fourth port via the third port, and most of the light signal is transmitted and emitted by the scanning system, and the light beam reflected by the measured object is output from the fourth port after passing through the third port. Therefore, the vehicle-mounted laser radar system of the present invention integrates the four main structures of amplification, emission, scanning and detection and reception of optical signals into one through the optical router, and the emission and reception are coaxial optical paths, which has the advantages of high integration, low system loss, simple optical path, compact structure, etc.

Description

Technical Field

[0001] The present invention belongs to the field of optical fiber communication and vehicle-mounted radar technology, and in particular relates to a highly integrated vehicle-mounted laser radar system. Background Art

[0002] On-board LiDAR is one of the essential core sensors in the multi-sensor system of future intelligent assisted driving and driverless cars. With the rapid development of the driverless market, more and more companies are joining in the development of new applications for LiDAR and the pursuit of advanced technologies. The principle of LiDAR is to determine the distance, speed and direction of the target by measuring the time difference and phase difference of the laser signal. The scanning method is mechanical, MEMS scanning or phased scanning. The ranging accuracy of on-board LiDAR is extremely important for the positioning and obstacle avoidance of autonomous driving. How to accurately calibrate and measure the ranging accuracy of LiDAR has become an urgent problem to be solved in the industry.

[0003] LiDAR has two working modes: TOF and FMCW. ToF uses time to measure distance, while FMCW uses frequency to measure distance. Figure 2 As shown in the figure, the distance measurement principle is to use the flight time of the light pulse between the transmitter, the target, and the receiver to measure the distance. The distance between the transmitter and the target is D, and the time delay between the transmitted light signal and the received light signal is τ, so τ = 2D / C, where C is the speed of light. TOF is an intensity signal and is easily drowned out by the background light signal.

[0004] FMCW (Frequency Modulated Continuous Wave) is a frequency modulated continuous wave. Its principle is: based on the coherence principle, the light reflected by the target interferes with the local light emitted by itself. FMCW is continuous light interference, which can extract the light signal with the same local characteristic spectrum from the chaotic background light without being interfered by various stray lights, which means that more accurate target detection can be achieved. Figure 3 As shown, the emitted local light signal is L. After passing through the spectrometer, part of the reflected local light L0=L*R1*R2, and the signal light reflected by the target object after transmission is S0=L*T1*R0*T2, wherein L is the intensity of the emitted signal light, R1 and T1 are the reflection and transmittance of the spectrometer, R1+T1=1, R2 and T2 are the reflection and transmittance of the mixing device, R2+T2=1, R0 is the reflectivity of the light signal reflected back by the object to be measured in the air, and part of the body light L0 and S0 reflected by the target object interfere with each other on the mixing device and are received.

[0005] An existing vehicle-mounted laser radar system structure is as follows: Figure 1As shown in the figure, the signal light emitted by the laser light source is emitted to the object to be measured through the scanning device, and the light reflected by the object to be measured is received by the receiver for signal analysis and processing, thereby calculating the distance and speed of the object to be measured. In this structure, the amplification of the seed light source light signal of the laser light source is a separate optical path amplification structure, and the emission of the amplified light signal and the reception of the reflected signal are independent, so that the entire laser radar system structure is large, the cost is high, and the system loss is also large. Summary of the invention

[0006] In view of this, in order to overcome the defects and shortcomings of the prior art, the present invention provides a highly integrated vehicle-mounted lidar system, which integrates the amplification, transmission, scanning and detection and reception of optical signals through an optical router. The transmission and reception are coaxial optical paths, which have the advantages of high integration, low system loss, simple optical path, compact structure, etc.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A highly integrated vehicle-mounted laser radar system comprises a seed light source, an optical routing device, a pump light source, an amplifying optical fiber, a partial reflector, a scanning system, a detector and a signal processing device; the seed light source is connected to the first port of the optical routing device, the pump light source is connected to the second port of the optical routing device through the amplifying optical fiber, the partial reflector and the scanning system are arranged at the third port of the optical routing device, and the detector and the signal processing device are arranged at the fourth port of the optical routing device; the optical signal input by the seed light source is input from the first port of the optical routing device, and is output from the second port after passing through the optical routing device; the optical signal is amplified by the amplifying optical fiber and the pump light source, and the amplified optical signal returns to the second port and is output from the third port of the optical routing device; a small part of the optical signal is reflected after passing through the partial reflector, and the reflected part of the light beam enters the third port for input and is output from the fourth port for reception by the detector, and most of the light signal is transmitted and irradiated to the object to be measured through the scanning system, and the part of the light beam reflected by the object to be measured enters the third port for input and is output from the fourth port for reception by the detector.

[0009] Furthermore, the four ports of the optical router device integrate the four main structures of amplification, emission, scanning and detection and reception of the laser radar optical signal, and each port can be flexibly configured.

[0010] Furthermore, it is applicable to two laser radar working modes: TOF and FMCW.

[0011] Furthermore, in the TOF mode, part of the reflected light from the third port functions as a spectroscopic detector.

[0012] Furthermore, in the FMCW mode, a small portion of the light signal reflected by the partial reflector and a portion of the light signal reflected back by the object to be measured interfere with each other on the partial reflector, and the interference signal is received by the detector and obtained through a signal processing device to obtain a coherent signal and then obtain the distance, speed and direction of the object to be measured.

[0013] Furthermore, the transmitting and receiving optical paths of the third port of the optical routing device are coaxial optical paths to achieve maximum receiving efficiency.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention provides a highly integrated vehicle-mounted laser radar system, which integrates the four main structures of laser radar optical signal amplification, emission, scanning and detection and reception through four ports of an optical router, thereby achieving high integration of the radar system and compact structure. In addition, the present invention has more advantages in FMCW mode, because the optical signal emission and reception in the third port are coaxial optical paths, and the partial local optical signal reflected by the partial reflector and the partial optical signal reflected back by the measured object interfere on the partial reflector. The local optical signal is L, the reflection and transmittance of the partial reflector are R1 and T1 respectively, the reflected partial local signal light L0=L*R1, the reflected partial signal light S0=L*T1*R0*T1, R1+T1=1, R0 is the reflectivity of the optical signal reflected back by the object to be measured in the air; in the FMCW mode of the existing laser radar system, L0=L*R1*R2, S0=L*T1*R0*T2, R1+T1=1, R2+T2=1, when R1=0.1%, T1=99.9%, R2=0.1%, T2=99.9%, it can be concluded that in the FMCW mode of the coaxial optical path structure of the present invention, the received partial local optical signal L0 is one hundred times stronger than the partial local optical signal received in the existing FMCW mode, achieving maximum receiving efficiency, so the system loss of the present invention is significantly smaller, and more accurate target detection is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of an existing vehicle-mounted laser radar system.

[0017] Figure 2 It is a schematic diagram of the TOF mode ranging principle of the existing lidar system.

[0018] Figure 3 It is a schematic diagram of the FMCW mode detection principle of the existing laser radar system.

[0019] Figure 4 It is a schematic diagram of the structure of a highly integrated vehicle-mounted laser radar system according to an embodiment of the present invention.

[0020] Figure 5It is a schematic diagram of the FMCW mode optical path principle of the coaxial optical path structure in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] like Figure 4 As shown, an embodiment of the present invention provides a highly integrated vehicle-mounted laser radar system, including a seed light source 11, an optical routing device 5, a pump light source 21, an amplifying optical fiber 22, a partial reflector 6, a scanning system 7, a detector 41 and a signal processing device 42; the seed light source 11 is connected to the first port 1 of the optical routing device 5, the pump light source 21 is connected to the second port 2 of the optical routing device 5 through the amplifying optical fiber 22, the partial reflector 6 and the scanning system 7 are arranged at the third port 3 of the optical routing device 5, and the detector 41 and the signal processing device 42 are arranged at the fourth port 4 of the optical routing device 5.

[0023] The optical signal input by the seed light source 11 is input from the first port 1 of the optical router device 5, and is output from the second port 2 after passing through the optical router device 5; after being amplified by the amplifying optical fiber 22 and the pump light source 21, the amplified optical signal returns to the second port 2 and is output from the third port 3 of the optical router device 5; after passing through the partial reflector 6, a small part of the optical signal is reflected, and the reflected partial light beam enters the third port 3 for input and is output from the fourth port 4 to be received by the detector 41; most of the optical signal is transmitted and irradiated to the object to be measured 8 through the scanning system 7, and the partial light beam reflected by the object to be measured 8 enters the third port 3 for input and is output from the fourth port 4 to be received by the detector 41.

[0024] Preferably, the four ports of the optical router device 5 integrate the four main structures of amplification, emission, scanning and detection and reception of the laser radar optical signal, and each port can be flexibly configured.

[0025] Preferably, the present invention is applicable to two laser radar working modes: TOF and FMCW.

[0026] Preferably, in the TOF mode, part of the reflected light from the third port 3 functions as a spectroscopic detector.

[0027] Preferably, in the FMCW mode, a small portion of the light signal reflected by the partial reflector 6 and a portion of the light signal reflected back by the object to be measured 8 interfere with each other on the partial reflector 6, and the interference signal is received by the detector 41 and obtained through the signal processing device 42 to obtain a coherent signal and then obtain the distance, speed and direction of the object to be measured 8.

[0028] Preferably, the transmitting and receiving optical paths of the third port 3 of the optical routing device 5 are coaxial optical paths to achieve maximum receiving efficiency.

[0029] The specific implementation process of the present invention is as follows:

[0030] like Figure 4 As shown, in the embodiment of the present invention, the optical signal input by the seed light source 11 is input by the first port 1 of the optical router device 5, and the optical router device 5 includes a first prism 51, a magneto-optical crystal 52, a wave plate 53, and a second prism 54. The first prism 51, the magneto-optical crystal 52, the wave plate 53, and the second prism 54 are arranged from right to left between the third port 3 and the second port 2 of the optical router device 5. The optical signal input by the seed light source 11 is output from the second port 2 after passing through the optical router device 5. The output optical signal is amplified by the amplifying optical fiber 22 and the pump light source 21, and the amplified optical signal returns to the second port 2, and is output from the third port 3 of the optical router device 5 after passing through the optical router device 5. The amplified local optical signal passes through a partial reflector 6 with a reflectivity of 0.001% to 5%. A reflective and transmissive film is plated on the surface 61 of the partial reflector 6. A small part of the local optical signal L0 is reflected. The reflected partial light beam is reflected back to the third port 3 for input and then outputted from the fourth port 4 and received by the detector 41. Most of the local optical signal is transmitted and irradiated to the object 8 to be measured through the scanning system 7. The partial light beam reflected by the object 8 to be measured enters the third port 3 for input and then outputted from the fourth port 4 and received by the detector 41. After the signal received by the detector 41 is processed and analyzed by the signal processing device 42, information such as the distance, moving speed and direction of the object to be measured can be calculated.

[0031] In TOF mode, the light directly reflected from the partial reflector 6 and received by the detector 41 is used as the t0 signal; the light transmitted from the partial reflector 6 and then reflected from the measured object 8 and finally received by the detector 41 is used as the t1 signal. D = (t1-t0)*C / 2, C is the speed of light, and D is the distance of the measured object 8. The strength of the t0 signal also serves as the TAP PD, that is, the monitoring function of the output power strength.

[0032] like Figure 5As shown, in FMCW mode, the output from the third port 3 as the input and output port is a continuous light wave modulated signal, the amplified local signal light is L, a part of which is continuously reflected from the partial reflector 6, the reflection and transmittance of the partial reflector 6 are R1 and T1 respectively, and the reflected local signal light L0=L*R1; most of which is continuously transmitted from the partial reflector 6 and continuously reflected from the object to be measured 8, and the reflected partial signal light S0=L*T1*R0*T1, where R1+T1=1, and R0 is the reflectivity of the light signal reflected back by the object to be measured in the air. These two parts of light interfere on the surface 61 of the partial reflector 6 to form interference light with distance and speed information, enter the third port 3, pass through the optical routing device 5, and are output from the fourth port 4, and then received by the detector 41. The signal received by the detector 41 is processed by the signal processing device 42 to obtain the position distance, moving speed and direction of the object to be measured 8.

[0033] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of highly integrated vehicle-mounted laser radar systems under the inspiration of the present invention. All equal changes and modifications made within the scope of the present invention should be covered by the present invention.

Claims

1. A highly integrated vehicle-mounted laser radar system, characterized in that: The invention comprises a seed light source, an optical routing device, a pump light source, an amplifying optical fiber, a partial reflector, a scanning system, a detector and a signal processing device; the seed light source is connected to the first port of the optical routing device, the pump light source is connected to the second port of the optical routing device through the amplifying optical fiber, the partial reflector and the scanning system are arranged at the third port of the optical routing device, and the detector and the signal processing device are arranged at the fourth port of the optical routing device; the optical signal input by the seed light source is input from the first port of the optical routing device, and is output from the second port after passing through the optical routing device; After being amplified by the amplifying optical fiber and the pump light source, the amplified optical signal returns to the second port and is output from the third port of the optical routing device; after passing through the partial reflector, a small part of the optical signal is reflected, and the reflected light beam enters the third port and is output from the fourth port to be received by the detector; after most of the optical signal is transmitted, it is emitted by the scanning system, and the light beam reflected by the measured object enters the third port and is output from the fourth port to be received by the detector; Applicable to TOF and FMCW laser radar working modes; In the TOF mode, part of the reflected light from the third port functions as a spectroscopic detector; In the FMCW mode, a small portion of the light signal reflected by the partial reflector and a portion of the light signal reflected back by the object to be measured interfere with each other on the partial reflector. The interference signal is received by the detector and a coherent signal is obtained through a signal processing device to obtain the distance, speed and direction of the object to be measured.

2. The highly integrated vehicle-mounted laser radar system according to claim 1, characterized in that: The four ports of the optical router device integrate the four structures of amplification, emission, scanning and detection and reception of laser radar optical signals, and each port can be flexibly configured.

3. The highly integrated vehicle-mounted laser radar system according to claim 1, characterized in that: The transmitting and receiving optical paths of the third port of the optical routing device are coaxial optical paths, thus achieving maximum receiving efficiency.

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