阅读说明：本技术 基于铒玻璃激光器的并行调频连续波激光测距装置 (Parallel frequency modulation continuous wave laser ranging device based on erbium glass laser ) 是由 王云祥 李响 邱琪 于 2020-06-12 设计创作，主要内容包括：本发明涉及基于铒玻璃激光器的并行调频连续波激光测距装置,包括：泵浦源产生的激光通过腔镜,将形成的多纵模线性调频激光传输到光分路器,在腔镜内还设有铒玻璃和电光晶体,由泵浦源、铒玻璃、和腔镜共同构成了铒玻璃激光器。所述光分路器的第一输出端连接光环行器第一端口,光环行器的第二端口依次连接透射光栅和发射/接收光学望远镜,光分路器的第二输出端与光环行器第三端口共同输出至耦合器的输入端,耦合器的输出端依次连接解波分复用器、接收混频模块和信号处理模块。本发明能够对多纵模激光进行简单稳定的线性调频,大幅度提高了测量的精度和分辨率,实现了多通道并行调频连续波激光测距测速。(The invention relates to a parallel frequency modulation continuous wave laser ranging device based on an erbium glass laser, which comprises: the laser generated by the pumping source is transmitted to the optical splitter through the cavity mirror, the erbium glass and the electro-optic crystal are arranged in the cavity mirror, and the pumping source, the erbium glass and the cavity mirror jointly form the erbium glass laser. The first output end of the optical splitter is connected with a first port of an optical circulator, a second port of the optical circulator is sequentially connected with a transmission grating and a transmitting/receiving optical telescope, the second output end of the optical splitter and a third port of the optical circulator are jointly output to the input end of the coupler, and the output end of the coupler is sequentially connected with the wavelength division demultiplexer, the receiving mixing module and the signal processing module. The invention can simply and stably carry out linear frequency modulation on multi-longitudinal-mode laser, greatly improves the measurement precision and resolution and realizes the distance measurement and speed measurement of multi-channel parallel frequency modulation continuous wave laser.)

1. Parallel frequency modulation continuous wave laser range unit based on erbium glass laser instrument, its characteristic includes: laser (3) generated by a pumping source (1) transmits formed multi-longitudinal-mode linear frequency modulation laser (9) to an optical splitter (10) through a cavity mirror, erbium glass (6) and an electro-optical crystal (7) are further arranged in the cavity mirror, a first output end of the optical splitter (10) is connected with a first port of an optical circulator (11), a second port of the optical circulator (11) is sequentially connected with a transmission grating (12) and a transmitting/receiving optical telescope (13), a second output end of the optical splitter (10) and a third port of the optical circulator (11) are jointly output to an input end of a coupler (15), and an output end of the coupler (15) is sequentially connected with a de-wavelength division multiplexer (16), a receiving mixing module (17) and a signal processing module (18).

2. The erbium glass laser-based parallel frequency-modulated continuous wave laser ranging device as claimed in claim 1, wherein: the pump source (1) is a semiconductor laser with an emission spectrum matched with an absorption spectrum of erbium glass (6).

3. The erbium glass laser-based parallel frequency-modulated continuous wave laser ranging device as claimed in claim 1, wherein: the cavity mirror at least comprises a rear cavity mirror (5) and an output mirror (8), wherein the rear cavity mirror (5) is used for highly reflecting and increasing the reflection of the laser (3), and the output mirror (8) is used for partially transmitting the laser (3).

4. The erbium glass laser-based parallel frequency-modulated continuous wave laser ranging device as claimed in claim 1, wherein: laser (3) emitted by the pump source (1) is coupled through the optical fiber (2), focused by the coupling lens (4) and then enters the erbium glass (6).

5. The erbium glass laser-based parallel frequency-modulated continuous wave laser ranging device as claimed in claim 1, wherein: the transmission grating (12) is used for carrying out frequency spectrum separation on the laser (3), and the transmission frequency interval of the transmission grating (12) is matched with the longitudinal mode interval of the multi-longitudinal mode linear frequency modulation laser (9); the transmitting channel of the transmitting/receiving optical telescope (13) is connected with the transmission grating (12), and the receiving channel is connected with the wavelength division multiplexer (16); the wavelength division multiplexer (16) is used for performing spectrum separation on the echo light beams (14), and the channel spacing of the wavelength division multiplexer (16) is matched with the longitudinal mode spacing of the multi-longitudinal mode chirp laser (9).

6. The erbium glass laser-based parallel frequency-modulated continuous wave laser ranging device as claimed in claim 1, wherein: and a photoelectric detector, a signal amplifier, a mixer and a low-pass filter are arranged in the receiving and mixing module (17) according to the signal transmission direction and are used for receiving and processing the echo light beam (14) and obtaining a difference frequency signal containing target information.

7. An erbium glass laser-based parallel frequency modulated continuous wave laser ranging device as claimed in any one of claims 1 to 6, wherein: the electro-optic crystal (7) is LiNbO₃、LiTaO₃Crystals of KDP, KTP or RTP.

8. An erbium glass laser-based parallel frequency modulated continuous wave laser ranging device as claimed in any one of claims 1 to 6, wherein: the erbium glass (6) is doped Er³⁺The phosphate laser glass of (1).

Technical Field

The invention relates to a laser ranging device, in particular to a parallel frequency modulation continuous wave laser ranging device based on an erbium glass laser.

Background

The laser radar technology has the advantages of high imaging resolution, high automation degree, non-contact, easy integration and the like, can accurately and quickly acquire three-dimensional space information of a target, is widely applied to the automatic driving technology, and is a key component for continuous development of automatic driving automobiles.

Most of the lidar currently on the market use a first generation pulse technique known as time of flight (TOF). The method is characterized in that a laser system emits a laser pulse to a target, and the round-trip time of the pulse is measured to realize target distance detection. The Frequency Modulation Continuous Wave (FMCW) laser radar is based on the coherent laser ranging principle, the technology enables the transmitting laser frequency of the laser radar to change linearly along with time, a difference frequency signal formed by a laser transmitting signal and an echo signal is obtained through a laser interference technology, and distance information of a target is extracted from the difference frequency signal. The frequency modulation continuous wave technology greatly enhances the range resolution of the laser radar, can directly detect the speed by using the Doppler effect, and can effectively prevent background radiation or interference of other radars.

In order to improve the radar sampling rate, the modern laser radar system adopts a laser array to replace the traditional mechanical scanning (Schwarz B.mapping the world in 3D [ J ] Nature Photonics,2010,4(7): 429-. In addition, the method requires a large number of lasers, is high in cost, and is not suitable for mass production. Recently, researchers at the sonsan federal institute of technology have proposed coupling a single frequency modulated continuous wave pump laser into an integrated silicon nitride microcavity to generate soliton microcombs, and synchronously frequency tuning the pump laser to the comb teeth of all the frequency combs, thereby implementing a multichannel parallel coherent lidar array (riemens berger J, Lukashchuk a, karpom, et al. massively parallel coherent laser ranging a soliton microcomb [ J ]. Nature,2020,581, (7807): 164-. The method has the disadvantages of high device complexity, low coupling efficiency of the optical fiber and the silicon nitride microcavity and high device cost. Therefore, the parallel frequency modulation continuous wave laser ranging technology has important research and application values.

Disclosure of Invention

The invention provides a parallel frequency modulation continuous wave laser distance measuring device based on an erbium glass laser, which can simply and stably perform linear frequency modulation on multi-longitudinal mode laser, improve the measurement precision and resolution and realize multi-channel parallel frequency modulation continuous wave laser distance measurement and speed measurement.

The invention relates to a parallel frequency modulation continuous wave laser ranging device based on an erbium glass laser, which comprises: the laser generated by the pumping source is transmitted to the optical splitter through the cavity mirror, the erbium glass and the electro-optic crystal are arranged in the cavity mirror, and the pumping source, the erbium glass and the cavity mirror jointly form the erbium glass laser. The first output end of the optical splitter is connected with a first port of an optical circulator, a second port of the optical circulator is sequentially connected with a transmission grating and a transmitting/receiving optical telescope, the second output end of the optical splitter and a third port of the optical circulator are jointly output to the input end of the coupler, and the output end of the coupler is sequentially connected with the wavelength division demultiplexer, the receiving mixing module and the signal processing module.

The invention modulates the multi-longitudinal-mode narrow-linewidth laser by the electro-optical effect and realizes simple and stable linear frequency modulation. If the mode of directly injecting current into the semiconductor laser is used, most semiconductor lasers have serious frequency modulation nonlinear phenomena due to factors such as tuning mechanisms, internal structures and the like, and measurement accuracy and resolution are affected. The frequency modulation by using the electro-optical crystal mode of the invention does not need to consider the nonlinear influence in the frequency modulation process, and can realize stable laser linear frequency modulation by controlling the linear change of the external voltage of the electro-optical crystal along with the time.

Furthermore, the pump source is a semiconductor laser with an emission spectrum matched with an absorption spectrum of erbium glass, and can also be other types of laser generators.

Furthermore, the cavity mirror at least comprises a back cavity mirror and an output mirror, wherein the back cavity mirror is used for high reflection and anti-reflection of laser, and the output mirror is used for partial transmission of the laser.

Furthermore, laser emitted by the pump source is coupled through an optical fiber, focused by a coupling lens and then incident on erbium glass.

Furthermore, the transmission grating is used for carrying out frequency spectrum separation on the laser, and the transmission frequency interval of the transmission grating is matched with the longitudinal mode interval of the multi-longitudinal mode linear frequency modulation laser; the transmitting channel of the transmitting/receiving optical telescope is connected with the transmission grating, and the receiving channel is connected with the wavelength division multiplexer; the wavelength division demultiplexer is used for performing spectrum separation on the echo light beams, and the channel spacing of the wavelength division demultiplexer is matched with the longitudinal mode spacing of the multi-longitudinal mode linear frequency modulation laser.

Furthermore, a photoelectric detector, a signal amplifier, a mixer and a low-pass filter are arranged in the receiving and mixing module according to the signal transmission direction, and are used for receiving and processing the echo light beam and obtaining a difference frequency signal containing target information. The photoelectric detector converts the frequency-modulated optical signal into an electric signal; the signal amplifier amplifies the frequency modulation signal output by the photoelectric detector; the mixer mixes the signal output by the amplifier with a local oscillation signal; the low-pass filter filters out high-frequency components in the difference frequency signal to obtain a difference frequency signal containing the target distance. And finally, carrying out frequency spectrum analysis on the difference frequency signal through the signal processing module to further obtain the target distance, wherein the process is usually carried out on a computer.

Optionally, the electro-optic crystal is LiNbO₃、LiTaO₃Crystals of KDP, KTP or RTP. The refractive index of laser passing through the electro-optical crystal is changed by applying the voltage linearly changing along with time to the two ends of the electro-optical crystal, so that the linear frequency modulation of each longitudinal mode laser is realized.

Preferably, the erbium glass is doped Er³⁺The phosphate laser glass of (2) is a solid laser working substance which generates laser output.

The components involved in the invention are all existing components, and the innovation point of the invention is a connecting structure applied to the combination of the existing components.

According to the parallel frequency modulation continuous wave laser ranging device based on the erbium glass laser, the erbium-doped laser glass is used as a gain medium, the spectral width and the number of longitudinal modes of laser radiation are increased, each longitudinal mode can be used as an independent laser radar channel, and the working efficiency of a laser radar is greatly improved. And the laser emission power of the pumping source is high, and the pumping source is used as a laser radar light source without light amplification, so that the complexity and the price of the system are effectively reduced, and the pumping source can be widely applied to automatic driving vehicles.

The present invention will be described in further detail with reference to the following examples. This should not be understood as limiting the scope of the above-described subject matter of the present invention to the following examples. Various substitutions and alterations according to the general knowledge and conventional practice in the art are intended to be included within the scope of the present invention without departing from the technical spirit of the present invention as described above.

Drawings

Fig. 1 is a schematic structural diagram of a parallel frequency modulation continuous wave laser ranging device based on an erbium glass laser.

Fig. 2 is a schematic diagram of the laser ranging of fig. 1.

Reference numerals: the device comprises a pumping source 1, a coupling optical fiber 2, laser 3, a coupling lens 4, a rear cavity mirror 5, erbium glass 6, an electro-optical crystal 7, an output mirror 8, multi-longitudinal mode linear frequency modulation laser 9, an optical beam splitter 10, an optical circulator 11, a transmission grating 12, a transmitting/receiving optical telescope 13, an echo beam 14, a coupler 15, a wavelength division multiplexer 16, a receiving frequency mixing module 17, a signal processing module 18, a detection beam time-frequency curve 19 and an echo beam time-frequency curve 20.

Detailed Description

As shown in figure 1, the parallel frequency modulation continuous wave laser ranging device based on the erbium glass laser comprises a cavity mirror, wherein laser 3 generated by a pumping source 1 is coupled through an optical fiber 2 and then is focused through a coupling lens 4 and then enters the cavity mirror, the cavity mirror at least comprises a back cavity mirror 5 and an output mirror 8, the back cavity mirror 5 is used for highly reflecting and increasing the reflection of the laser 3, and the output mirror 8 is used for partially transmitting the laser 3. An erbium glass 6 and an electro-optical crystal 7 are also arranged in the cavity mirror. Comprises a pump source 1, an erbium glass 6, and a cavityThe mirrors together constitute an erbium glass laser. The electro-optic crystal 7 is LiNbO₃，LiTaO₃Crystals of KDP, KTP or RTP. The erbium glass 6 is doped Er³⁺The phosphate laser glass of (2) is a solid laser working substance which generates laser output. The pump source 1 is a semiconductor laser with an emission spectrum matched with an absorption spectrum of the erbium glass 6. The laser 3 passes through a cavity mirror, erbium glass 6 and an electro-optical crystal 7, and then transmits the formed multi-longitudinal mode linear frequency modulation laser 9 to an optical splitter 10. The refractive index of the laser 3 passing through the electro-optical crystal 7 is changed by applying a voltage linearly changing with time to the two ends of the electro-optical crystal 7, so that the linear frequency modulation of each longitudinal mode laser is realized.

The first output end of the optical splitter 10 is connected with the first port of the optical circulator 11, the second port of the optical circulator 11 is sequentially connected with the transmission grating 12 and the transmitting/receiving optical telescope 13, the second output end of the optical splitter 10 and the third port of the optical circulator 11 are jointly output to the input end of the coupler 15, and the output end of the coupler 15 is sequentially connected with the wavelength division demultiplexer 16, the receiving mixing module 17 and the signal processing module 18.

The transmission grating 12 is used for performing spectrum separation on the laser 3, and the transmission frequency interval of the transmission grating 12 is matched with the longitudinal mode interval of the multi-longitudinal mode chirp laser 9. The transmitting channel of the transmitting/receiving optical telescope 13 is connected with the transmission grating 12, and the receiving channel is connected with the wavelength division multiplexer 16. The wavelength division multiplexer 16 is used for performing spectrum separation on the echo light beam 14, and the channel spacing of the wavelength division multiplexer 16 is matched with the longitudinal mode spacing of the multi-longitudinal mode chirp laser 9. The receiving and mixing module 17 is provided with a photodetector, a signal amplifier, a mixer and a low-pass filter in the signal transmission direction, and is configured to receive and process the echo light beam 14 and obtain a difference frequency signal containing target information. The photoelectric detector converts the frequency-modulated optical signal into an electric signal; the signal amplifier amplifies the frequency modulation signal output by the photoelectric detector; the frequency mixer mixes the signal output by the amplifier with a local oscillation signal; and the low-pass filter filters high-frequency components in the difference frequency signal to obtain a difference frequency signal containing the target distance. And finally, performing spectrum analysis on the difference frequency signal through the signal processing module 18 to further obtain the target distance.