Wind measurement laser radar and wind measurement method

Abstract

The invention relates to a wind measurement laser radar and a wind measurement method. The laser radar comprises a first light source, a beam splitter, a mixed light annular module, an adjusting module, a processing module and a detection module, and by adopting the laser radar, through cooperative use of the mixed light annular module and the adjusting module, two times of frequency modulation, two times of pulse modulation and two times of power amplification can be performed on signal light of a to-be-detected target; and a hybrid optical annular module design is adopted, so that the number of passive optical devices is reduced, the integration level of the laser radar can be improved, and the additional insertion loss is small.

Description

Technical Field

[0001] The present application relates to the field of laser radar technology, and in particular to a wind measurement laser radar and a wind measurement method. Background Art

[0002] With the development of lidar technology, lidar wind measurement technology has emerged. Wind measurement lidar measures the Doppler frequency shift of the backscattered signal of aerosol particles to obtain the inverted wind speed.

[0003] At present, the mainstream forms of short-range wind measurement lidar systems are nacelle-type and ground-based types. Nacelle-type wind measurement lidar is used for wind turbine yaw calibration, wind power prediction, etc., while ground-based wind measurement lidar is used for wind turbine early site selection and wind power prediction, etc.

[0004] With the development of the wind power industry, higher requirements are placed on the cost, size and power consumption of short-range wind measurement lidar. Summary of the invention

[0005] Based on this, it is necessary to provide a more integrated wind measurement lidar and wind measurement method that can meet the low cost, low power consumption and high reliability requirements of the wind power industry in response to the above technical problems.

[0006] In a first aspect, the present application provides a wind measuring laser radar, which includes: a first light source, which emits a first laser with a first wavelength; a beam splitter, which receives the first laser and splits the first laser into a local oscillator light and a first signal light; a hybrid light ring module, which includes a first port and a second port; the hybrid light ring module receives the first signal light through the first port and outputs the first signal light from the second port; an adjustment module, which receives the first signal light from the second port and is used to perform two frequency modulations, two pulse modulations and two power amplifications on the first signal light to obtain a second signal light; the hybrid light ring module also includes a third port, the second port of the hybrid light ring module also receives the second signal light, and outputs the second signal light from the third port; a processing module, which receives the second signal light from the third port, transmits the second signal light to a target to be measured, and receives an echo signal reflected from the target to be measured; the hybrid light ring module also includes a detection port, the third port of the hybrid light ring module also receives an echo signal, and transmits the echo signal to the detection port; a detection module, which receives the echo signal and the local oscillator light output by the detection port, thereby generating a wind speed signal of the target to be measured.

[0007] In one embodiment, the adjustment module includes: an acousto-optic module, which receives a first signal light and performs frequency modulation and pulse modulation on the first signal light to obtain a third signal light; a second light source, which emits a second laser with a second wavelength; an erbium-doped optical fiber, which receives and transmits the third signal light and the second laser, and the third signal light is transmitted and amplified along a first direction in the erbium-doped optical fiber under the action of the second laser to obtain a fourth signal light; a reflection module, which receives the fourth signal light and the second laser and reflects the fourth signal light and the second laser back to the erbium-doped optical fiber; the fourth signal light is transmitted and amplified again along a second direction in the erbium-doped optical fiber under the action of the second laser, and is incident on the acousto-optic module again, and is frequency modulated and pulse modulated by the acousto-optic module to obtain the second signal light; the second direction is opposite to the first direction.

[0008] In one embodiment, the second laser is transmitted along the second direction.

[0009] In one embodiment, the reflection module includes: a lens, receiving the fourth signal light and the second laser, and adjusting the fourth signal light and the second laser; a color filter, receiving the fourth signal light and the second laser adjusted by the lens, reflecting the second laser and transmitting the fourth signal light; the second laser is reflected to the lens, adjusted again by the lens and then incident on the erbium-doped optical fiber; a polarization rotation unit, receiving the fourth signal light, rotating the polarization direction of the fourth signal light by 90 degrees and then reflecting it to the color filter; the fourth signal light after the polarization direction is rotated by 90 degrees is incident on the erbium-doped optical fiber again after passing through the color filter and the lens.

[0010] In one embodiment, the hybrid optical ring module further includes a polarization beam splitter; the first signal light is received through the first port, deflected to the second port via the polarization beam splitter, and the first signal light is output from the second port; the second port of the hybrid optical ring module also receives the second signal light, the second signal light is deflected to the third port via the polarization beam splitter, and the second signal light is output from the third port.

[0011] In one embodiment, the repetition frequency of the first laser is between 1 kHz and 15 kHz.

[0012] In one embodiment, the repetition frequency of the first laser is 10 kHz.

[0013] In one embodiment, the polarization rotation unit includes: a Faraday rotation unit, used to receive the fourth signal light and rotate the polarization direction of the fourth signal light by 45 degrees under the action of the magnetic field; a reflector, receiving the fourth signal light with the polarization direction rotated by 45 degrees, and reflecting the fourth signal light with the polarization direction rotated by 45 degrees back to the Faraday rotation unit; the fourth signal light with the polarization direction rotated by 45 degrees passes through the Faraday rotation unit again, and the polarization direction is rotated by 45 degrees again before being incident on the color filter.

[0014] In one embodiment, the reflection module further includes a dual-core pin, which includes: a first pin port, which receives the second laser and transmits the second laser to the reflection module; and a second pin port, which is connected to the erbium-doped optical fiber and is used to receive the fourth signal light and transmit the fourth signal light to the reflection module; and is also used to receive the second laser and the fourth signal light reflected by the reflection module, and transmit the second laser and the fourth signal light to the erbium-doped optical fiber.

[0015] In one embodiment, the first port, the second port, the third port and the detection port of the hybrid optical ring module all use polarization-maintaining optical fibers, the slow axis of the polarization-maintaining optical fiber of the second port is aligned with the slow axis of the polarization-maintaining optical fiber of the first port, the fast axis of the polarization-maintaining optical fiber of the third port is aligned with the slow axis of the polarization-maintaining optical fiber of the second port, and the slow axis of the polarization-maintaining optical fiber of the detection port is aligned with the slow axis of the polarization-maintaining optical fiber of the third port.

[0016] In one embodiment, the processing module includes: an optical switch, used to switch the transmission channel and the receiving channel of the second signal light; a telescope, receiving the second signal light passing through the transmission channel opened by the optical switch and transmitting the second signal light to the target to be measured, receiving the echo signal reflected back by the target to be measured, and transmitting the echo signal to the receiving channel switched by the optical switch.

[0017] In one embodiment, the detection module includes: a coupler for coupling the echo signal and the local oscillator light to obtain a coupled light signal; a balanced detector for receiving the coupled light signal, beating the coupled light signal, and converting the coupled light signal after the beating into an electrical signal.

[0018] In a second aspect, the present application also provides a wind measurement method using a wind measurement laser radar, the method comprising:

[0019] Controlling the first light source to emit a first laser with a first wavelength, the first laser being split into a local oscillator light and a signal light by a beam splitter; the first signal light is transmitted to the second port of the hybrid light ring module through the first port of the hybrid light ring module, and is output from the second port;

[0020] The control and regulation module receives the first signal light from the second port, performs two frequency modulations, two pulse modulations, and two power amplifications on the first signal light to obtain a second signal light; the second signal light is incident on the hybrid light ring module through the second port, and is output from the third port of the hybrid light ring module;

[0021] The processing module receives the second signal light from the third port, transmits the second signal light to the target to be measured, and receives the echo signal reflected by the target to be measured; the echo signal is incident on the hybrid optical ring module through the third port, and is output from the detection port of the hybrid optical ring module;

[0022] The detection module receives the echo signal and the local oscillation light outputted from the detection port, thereby generating a wind speed signal of the target to be measured.

[0023] The above-mentioned wind measuring laser radar and wind measuring method include a first light source, a beam splitter, a hybrid light ring module, an adjustment module, a processing module and a detection module. The above-mentioned laser radar emits a first laser with a first wavelength through the first light source; and splits the first laser into a local oscillator light and a first signal light through the beam splitter; transmits the first signal light to the adjustment module through the hybrid light ring module, and uses the adjustment module to perform two frequency modulations, two pulse modulations and two power amplifications on the first signal light to obtain a second signal light; and uses the hybrid light ring module to transmit the second signal light to the processing module, so that the second signal light is emitted to the target to be measured, and the echo signal reflected by the target to be measured is received through the processing module; and, the echo signal is transmitted to the detection module again through the hybrid light ring module, so as to generate the wind speed signal of the target to be measured, so that through the coordinated use of the hybrid light ring module and the adjustment module, the signal light of the target to be detected can be frequency modulated twice, pulse modulated twice and power amplified twice, and the hybrid light ring module design is adopted to reduce the number of passive optical devices, which can improve the integration of the laser radar and reduce the additional insertion loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 is a schematic diagram of a wind measuring laser radar in one embodiment;

[0026] Figure 2 is a schematic diagram of a wind measuring laser radar in another embodiment;

[0027] Figure 3is a schematic diagram of a reflection module in one embodiment;

[0028] Figure 4 is a schematic diagram of a hybrid optical ring module in one embodiment;

[0029] Figure 5 The figure is a flow chart of a wind measurement method using a wind measuring laser radar in one embodiment.

[0030] Description of reference numerals:

[0031] 10. First light source; 20. Beam splitter; 30. Hybrid light ring module; 31. First port; 32. Second port; 33. Third port; 34. Detection port; 40. Adjustment module; 50. Processing module; 60. Detection module; 51. Optical switch; 52. Telescope; 41. Acoustic-optical module; 42. Erbium-doped optical fiber; 43. Second light source; 44. Reflection module; 61. Coupler; 62. Balanced detector; 441. Lens; 442. Color filter; 443. Polarization rotation unit; 4431. Faraday rotation unit; 4432. Reflector. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0033] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0034] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0035] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0037] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0038] Due to atmospheric loss, the aerosol backscattering coefficient of the laser radar output laser pulse is small, and the return light signal is a weak signal at the pW level. Therefore, in order to ensure the short-range detection distance of the wind laser radar and guarantee the wind measurement accuracy, an embodiment of the present invention provides a short-range wind laser radar.

[0039] See also Figure 1 , Figure 1A schematic diagram of a wind measurement laser radar in an embodiment of the present invention is shown. The laser radar provided in an embodiment of the present invention includes: a first light source 10, the first light source 10 emits a first laser with a first wavelength; a beam splitter 20, receiving the first laser, and splitting the first laser into a local oscillator light and a first signal light; a hybrid light ring module 30, including a first port 31 and a second port 32; the hybrid light ring module 30 receives the first signal light through the first port 31, and outputs the first signal light from the second port 32; an adjustment module 40, receiving the first signal light from the second port 32, and being used to perform two frequency modulations, two pulse modulations, and two power amplifications on the first signal light , obtaining a second signal light; the hybrid light ring module 30 also includes a third port 33, the second port 32 of the hybrid light ring module 30 also receives the second signal light, and outputs the second signal light from the third port 33; the processing module 50 receives the second signal light from the third port 33, emits the second signal light to the target to be measured, and receives the echo signal reflected by the target to be measured; the hybrid light ring module 30 also includes a detection port 34, the third port 33 of the hybrid light ring module 30 also receives the echo signal, and transmits the echo signal to the detection port 34; the detection module 60 receives the echo signal and the local oscillation light output by the detection port 34, thereby generating a wind speed signal of the target to be measured.

[0040] Among them, the beam splitter can be a polarization-maintaining fiber beam splitter. The splitting ratio of the beam splitter to the first laser can be 5 / 95 or 10 / 90 or 15 / 85. It can be understood that the splitting ratio is affected by the power of the first light source, the amplifier small signal input requirement and the optimal local oscillator light power for balanced detection. The splitting ratio can be determined based on the power of the first light source, the amplifier small signal input requirement and the optimal local oscillator light power for balanced detection. Exemplarily, the splitting ratio is 5 / 95.

[0041] In one embodiment, the first laser emitted by the first light source 10, such as a seed laser, is divided into two beams by the beam splitter 20, one beam is used as the local oscillator light, connected to the detection module 60, and the other beam is the first signal light, which is transmitted to the first port 31 of the hybrid light ring module 30, such as a four-port optical circulator, output from the second port 32, and transmitted to the adjustment module 40. The adjustment module 40 performs two frequency shifts, chops, and amplifies the incident first laser to become a pulse light of the second signal light, and then reflects it back to the second port 32. After that, the second signal light is emitted into the atmosphere through the third port 33 through the processing module 50. After receiving the aerosol backscattering signal, that is, the echo signal, the processing module 50 transmits the echo signal to the third port 33 of the hybrid light ring module 30, and then emits it from the detection port 34, and then transmits it to the detection module 60. The detection module 60 receives the echo signal and the local oscillator light output by the detection port 34, thereby generating a wind speed signal of the target to be measured.

[0042] In this embodiment, by using a hybrid optical ring module and an adjustment module in coordination, the signal light of the target to be detected can be frequency modulated twice, pulse modulated twice, and power amplified twice. The hybrid optical ring module 30 is designed to reduce the number of passive optical components, improve the integration of the laser radar, and reduce the additional insertion loss.

[0043] In one embodiment, the adjustment module 40 includes: an acousto-optic module 41, which receives the first signal light and performs frequency modulation and pulse modulation on the first signal light to obtain a third signal light; a second light source 43, which emits a second laser with a second wavelength; an erbium-doped optical fiber 42, which receives and transmits the third signal light and the second laser, and the third signal light is transmitted and amplified along the first direction in the erbium-doped optical fiber 42 under the action of the second laser to obtain a fourth signal light; a reflection module 44, which receives the fourth signal light and the second laser and reflects the fourth signal light and the second laser back to the erbium-doped optical fiber 42; the fourth signal light is transmitted and amplified again along the second direction in the erbium-doped optical fiber 42 under the action of the second laser, and is incident on the acousto-optic module 41 again, and is frequency modulated and pulse modulated by the acousto-optic module 41 to obtain a second signal light; the second direction is opposite to the first direction.

[0044] See also Figure 2 , Figure 2 A schematic diagram of a wind measuring laser radar in yet another embodiment of the present invention is shown.

[0045] Exemplarily, the first laser emitted by the first light source 10, such as a 1550nm single-frequency laser, is divided into two beams by a beam splitter, such as a 5 / 95 optical beam splitter, wherein a beam with 5% of the light intensity is used as the local oscillator light and is connected to the detection module 60. The beam with 95% of the light intensity is used as the signal light, which is transmitted to the first port 31 of the hybrid optical ring module 30, output from the second port 32, and transmitted to the acousto-optic module 41. The acousto-optic module 41 shifts the frequency of the incident continuous light, chops it into the third signal light, i.e., the pulse light, and then injects it into the erbium-doped optical fiber 42. The second light source 43, such as a 974nm single-mode pump laser, transmits the second laser with a second wavelength, i.e., the pump light, into the erbium-doped optical fiber 42. Under the action of the second laser, the third signal light is transmitted and amplified in the first direction in the erbium-doped optical fiber 42 to obtain the fourth signal light. After the fourth signal light and the second laser are reflected by the reflection module 44, they are again amplified by the erbium-doped optical fiber 42. After that, the sound and light module 41 is passed again, and the shut-off function of the sound and light module 41 is used to turn off the ASE of the adjacent pulse interval part to obtain the second signal light, which is then transmitted to the third port 33 through the second port 32 of the hybrid light ring module 30. After that, the second signal light is emitted into the atmosphere through the processing module 50. After receiving the aerosol backscattering signal, that is, the echo signal, the processing module 50 transmits the echo signal to the third port 33 of the hybrid light ring module 30, and then emits it from the detection port 34, and then transmits it to the detection module 60. The detection module 60 receives the echo signal and the local oscillation light outputted from the detection port 34, thereby generating a wind speed signal of the target to be measured.

[0046] It is understood that the first light source mentioned in the present application is a 1550nm single-frequency laser, and the second light source is a 974nm single-mode pump laser for example, which is exemplary and not restrictive. For example, the second light source may also include a 976nm pump laser. The frequency shift of the acousto-optic module, such as the acousto-optic modulator, is determined by the wind speed measurement range of the wind laser radar system, and typical values ​​are 40MHz, 60MHz, 80MHz, etc.

[0047] Among them, inter-pulse ASE (Amplified Spontaneous Emission) refers to the amplified spontaneous emission generated between laser pulses.

[0048] In pulsed laser systems, especially in high-power laser amplifiers, there is a certain time interval between pulses. During this time, the gain medium in the laser amplifier still has gain, so spontaneous radiation is generated and amplified, forming inter-pulse ASE. Inter-pulse ASE may interfere with the normal operation of the system, reduce the signal-to-noise ratio, and affect the measurement accuracy.

[0049] In this embodiment, an acousto-optic and fiber amplification hybrid double-pass optical path is adopted. The fiber-amplified double-pass amplifier improves the small signal gain and slope efficiency of the amplifier due to passing through the gain fiber twice, and has a larger small signal gain. The optical devices in the acousto-optic and amplifier hybrid double-pass link are streamlined, the optical additional loss is reduced, and the slope efficiency of the laser is improved; and the amplified pulse is chopped again through the acousto-optic module, on the one hand to ensure the system's 100dB extinction ratio requirement (the typical value of a single acousto-optic dynamic extinction ratio is 50dB), on the other hand, it can act as an optical switch to filter out the inter-pulse ASE, improve the side-mode suppression ratio (Side-Mode Suppression Ratio, SMSR) of the laser output, and improve the output pulse optical signal signal-to-noise ratio. Furthermore, through the double-pass amplification achieved by erbium-doped fiber, the wind measurement distance of the laser radar can reach the order of hundreds of meters under the condition of high integration of the single-stage amplification system.

[0050] In one embodiment, the repetition frequency of the first laser is between 1 kHz and 15 kHz.

[0051] Optionally, the repetition frequency of the first laser is 1 kHz, 2 kHz, 3 kHz, 4 kHz, 5 kHz, 6 kHz, 7 kHz, 8 kHz, 9 kHz, 10 kHz, 11 kHz, 12 kHz, 13 kHz, 14 kHz, or 15 kHz.

[0052] In one embodiment, the repetition frequency of the first laser is 10 kHz.

[0053] The wind laser radar optical system needs to meet the radar system signal-to-noise ratio and accuracy requirements. Considering that the system noise is shot noise, the laser radar equation is shown in formula (1): (1)

[0054] Where CNR is the carrier-to-noise ratio, is the optical system efficiency factor, is the laser single pulse energy, is the atmospheric backscattering coefficient, is the center wavelength of the emitted laser, is the atmospheric one-way loss coefficient, is the telescope aperture. is Planck's constant, is the circuit detection bandwidth, For the detection distance.

[0055] Under low carrier-to-noise ratio conditions, the wind laser radar velocity measurement accuracy formula is shown in formula (2): (2)

[0056] in is the speed standard deviation, is the signal spectrum bandwidth, is the number of pulse accumulation, is the number of sampling points within the range gate, and CNR is the carrier-to-noise ratio.

[0057] According to formula (1) and formula (2), the factors affecting the wind measurement accuracy in a single range gate are signal spectrum bandwidth, pulse accumulation times, sampling points, and signal-to-noise ratio. When only considering the influence of laser, the factors affecting wind measurement accuracy are pulse accumulation times. and laser single pulse energy .

[0058] Since the wind direction of the wind laser radar is synthesized from the radial wind speed vector, the pulse accumulation times Limited by the integration time. The radial wind speed integration time is defined as . Pulse accumulation times and radial wind speed integration time and pulse repetition frequency The relationship is shown in formula (3): (3)

[0059] The above formula can be defined Factor, through Factors are used to evaluate the correlation between laser parameters and wind measurement accuracy, as shown in formula (4): (4)

[0060] From formula (4), we can see that when The larger the factor, the smaller the wind laser radar velocity measurement accuracy, that is, the higher the laser radar velocity measurement accuracy. and pulse output average power The relationship between the pulse repetition frequency is shown in formula (5): (5)

[0061] Formula (6) can be obtained from formula (4) and formula (5): (6)

[0062] Depend on From the definition of the factor, it can be seen that when a low pulse repetition frequency is used and large laser single pulse energy The solution can also meet the needs of close-range wind measurement.

[0063] In order to achieve the effect of traditional two-stage amplification by single-stage double-pass amplification, the laser repetition frequency works at a low repetition frequency, with a typical value of less than 15kHz. Specifically, the pulse duty cycle and the number of pulse accumulations of the radar system need to be considered. In this embodiment, the repetition frequency of the first laser is designed to be 10kHz. The typical values ​​of pulse width are 200ns, 300ns, 400ns, etc., and the blind area and measurement distance of the wind laser radar system need to be comprehensively considered. In one embodiment, the pulse width is 300ns. Due to the high small signal gain and high slope efficiency characteristics of double-pass amplification and working at a low repetition frequency, the single pulse energy output by the light source is large, and the peak power of the laser output pulse is also large, which can easily reach the stimulated Brillouin scattering (SBS) threshold, thereby causing pulse trailing edge jitter to affect the wind measurement accuracy.

[0064] In this embodiment, the repetition frequency of the first laser is designed to be 10kHz, thereby increasing the single pulse energy under a certain average power condition, so that the single-stage amplified single pulse energy reaches the level of traditional two-stage amplification, eliminating the second-stage amplifier, and reducing the cost and power consumption of the radar system; and, in this implementation, starting from the laser radar equation and wind measurement accuracy, by optimizing the relationship between the number of pulse accumulation times and the single pulse energy, the single-stage optical fiber amplifier design is optimized, so that the amplifier works in a low repetition rate and high pulse energy mode, reducing one amplifier stage, that is, reducing the number of optical amplification stages, while reducing costs, power consumption, and size.

[0065] In one embodiment, the reflection module 44 includes: a lens 441, which receives the fourth signal light and the second laser, and adjusts the fourth signal light and the second laser; a color filter 442, which receives the fourth signal light and the second laser adjusted by the lens 441, reflects the second laser and transmits the fourth signal light; the second laser is reflected to the lens 441, and is adjusted again by the lens 441 before being incident on the erbium-doped optical fiber 42; a polarization rotation unit 443, which receives the fourth signal light, rotates the polarization direction of the fourth signal light by 90 degrees, and then reflects it to the color filter 442; the fourth signal light after the polarization direction is rotated by 90 degrees is incident on the erbium-doped optical fiber 42 again after passing through the color filter 442 and the lens 441.

[0066] When the first signal light enters the acousto-optic module, since the acousto-optic module includes a first surface and a second surface, both the first surface and the second surface will reflect the first signal light, and the reflected light will beat with the echo signal, thereby making the detection result inaccurate.

[0067] In order to solve the above problem, in one embodiment, the hybrid optical ring module also includes a polarization beam splitter; the first signal light is received through the first port and deflected to the second port via the polarization beam splitter, and the first signal light is output from the second port; the second port of the hybrid optical ring module also receives the second signal light, the second signal light is deflected to the third port via the polarization beam splitter, and the second signal light is output from the third port.

[0068] Exemplarily, when the first signal light received by the hybrid light ring module through the first port is in the first polarization state, for example, P light, the polarization beam splitter can reflect the first signal light in the first polarization state to the second port and emit it from the second port. After the first signal light is processed by the adjustment module, the polarization state changes by 90 degrees and becomes the second signal light in the second polarization state, for example, S light. After the second signal light is incident on the hybrid light ring module from the second port again, it is transmitted to the third port through the polarization beam splitter and emits from the third port. The adjustment module includes an acousto-optic module. It can be understood that the polarization state of the first signal light can also be the second polarization state, for example, S light, so that the polarization state of the second signal light can also be the first polarization state, for example, P light. It can be further understood that the polarization beam splitter can transmit the light in the first polarization state and reflect the light in the second polarization state, and the present application does not limit this.

[0069] When the first signal light passes through the acousto-optic module for the first time, most of the light will enter the subsequent amplification from the output fiber collimator after diffraction by the acousto-optic module, but a small part of the light will return to the incident fiber collimator of the acousto-optic module after a single frequency shift, and then be transmitted to the first port of the hybrid light ring module. Without special treatment, the secondary frequency-shifted amplified signal light and the stray light after the single frequency shift will interfere with each other, causing envelope modulation of the output pulse, affecting the wind measurement accuracy. In this embodiment, by setting a polarization beam splitter in the hybrid light ring module, when the first signal light passes through the acousto-optic module, the polarization state of the light reflected by the first surface or the second surface of the acousto-optic module is different from that of the echo signal. Therefore, the light reflected by the first surface or the second surface of the acousto-optic module will not form a beat frequency with the echo signal on the surface of the detector, thereby reducing noise interference and improving the accuracy of laser radar detection.

[0070] In one embodiment, the second laser is transmitted along the second direction.

[0071] For example, see Figure 3 , Figure 3Schematic diagram of a reflection module 44 in an embodiment, wherein the first laser emitted by the first light source 10 is divided into two beams by the beam splitter 20, and illustratively, a beam with 5% of the light intensity is used as the local oscillation light and is connected to the detection module 60. A beam with 95% of the light intensity is used as the signal light, which is transmitted to the first port 31 of the hybrid light ring module 30, output from the second port 32, and transmitted to the acousto-optic module 41. The acousto-optic module 41 shifts the frequency of the incident continuous light, chops it into the third signal light, i.e., pulse light, and then injects it into the erbium-doped fiber 42. The second light source 43, such as a 974nm single-mode pump laser, transmits the second laser with a second wavelength, i.e., the pump light, to the reflection module 44. The lens 441 of the reflection module 44 receives the fourth signal light and the second laser, and adjusts the fourth signal light and the second laser before injecting them onto the color filter 442. The color filter 442 receives the fourth signal light and the second laser adjusted by the lens 441, reflects the second laser and transmits the fourth signal light; the second laser is reflected to the lens 441, and is incident on the erbium-doped fiber 42 after being adjusted again by the lens 441. The fourth signal light passing through the color filter 442 is incident on the polarization rotation unit 443, and the polarization rotation unit 443 receives the fourth signal light, rotates the polarization direction of the fourth signal light by 90 degrees, and then reflects it to the color filter 442, and then passes through the color filter 442 and the lens 441 again before being incident on the erbium-doped fiber 42. Thus, the fourth signal light obtained after the amplification of the third signal light is reflected by the reflection module 44, the polarization state is rotated by 90°, and then passes through the erbium-doped fiber 42 again for secondary amplification. After that, it passes through the acousto-optic module 41 again, and the shut-off function of the acousto-optic module 41 is used to turn off the ASE of the adjacent pulse interval part to obtain the second signal light, and the second signal light is then transmitted to the third port 33 through the second port 32 of the hybrid optical ring module 30. Afterwards, the signal light is emitted into the atmosphere through the processing module 50. After receiving the aerosol backscattering signal, i.e., the echo signal, the processing module 50 transmits the echo signal to the third port 33 of the mixed light ring module 30, and then emits it from the detection port 34, and then transmits it to the detection module 60. The detection module 60 receives the echo signal and the local oscillation light output by the detection port 34, thereby generating a wind speed signal of the target to be measured.

[0072] In this embodiment, by transmitting the pump light in reverse, the integration of optical devices such as wavelength division multiplexers and reflection modules is facilitated, the length of the transmission optical fiber is shortened, and the nonlinear effect caused by SBS (Stimulated Brillouin scattering) is reduced.

[0073] In one embodiment, the polarization rotation unit 443 includes: a Faraday rotation unit 4431, which is used to receive the fourth signal light and rotate the polarization direction of the fourth signal light by 45 degrees under the action of the magnetic field; a reflector 4432, which receives the fourth signal light with the polarization direction rotated by 45 degrees, and reflects the fourth signal light with the polarization direction rotated by 45 degrees back to the Faraday rotation unit 4431; the fourth signal light with the polarization direction rotated by 45 degrees passes through the Faraday rotation unit again, and the polarization direction is rotated by 45 degrees again before being incident on the color filter 442.

[0074] For example, please refer again Figure 3 , Figure 3Schematic diagram of a reflection module 44 in an embodiment, wherein the first laser emitted by the first light source 10 is divided into two beams by the beam splitter 20, and illustratively, a beam with 5% of the light intensity is used as the local oscillation light and is connected to the detection module 60. A beam with 95% of the light intensity is used as the signal light, which is transmitted to the first port 31 of the hybrid light ring module 30, output from the second port 32, and transmitted to the acousto-optic module 41. The acousto-optic module 41 shifts the frequency of the incident continuous light, chops it into the third signal light, i.e., pulse light, and then injects it into the erbium-doped fiber 42. The second light source 43, such as a 974nm single-mode pump laser, transmits the second laser with a second wavelength, i.e., the pump light, to the reflection module 44. The lens 441 of the reflection module 44 receives the fourth signal light and the second laser, and adjusts the fourth signal light and the second laser before injecting them onto the color filter 442. The color filter 442 receives the fourth signal light and the second laser light adjusted by the lens 441, reflects the second laser light and transmits the fourth signal light; the second laser light is reflected to the lens 441, and is again adjusted by the lens 441 before being incident on the erbium-doped optical fiber 42. The fourth signal light passing through the color filter 442 is incident on the polarization rotation unit 443, and the Faraday rotation unit 4431 of the polarization rotation unit 443 receives the fourth signal light and rotates the polarization direction of the fourth signal light by 45 degrees under the action of the magnetic field. The reflector 4432 receives the fourth signal light with the polarization direction rotated by 45 degrees, and reflects the fourth signal light with the polarization direction rotated by 45 degrees back to the Faraday rotation unit 4431; the fourth signal light with the polarization direction rotated by 45 degrees passes through the Faraday rotation unit again, rotates the polarization direction by 45 degrees again, and then is incident on the color filter 442, and then passes through the color filter 442 and the lens 441 again before being incident on the erbium-doped optical fiber 42. Thus, the fourth signal light obtained after the amplification of the third signal light is reflected by the reflection module 44, the polarization state is rotated 90°, and then it is amplified again by the erbium-doped fiber 42. Then, it passes through the acousto-optic module 41 again, and the ASE of the adjacent pulse interval part is turned off by using the shut-off function of the acousto-optic module 41 to obtain the second signal light, which is then transmitted to the third port 33 through the second port 32 of the hybrid light ring module 30. Then, the signal light is emitted into the atmosphere through the processing module 50. After receiving the aerosol backscattering signal, that is, the echo signal, the processing module 50 transmits the echo signal to the third port 33 of the hybrid light ring module 30, and then emits it from the detection port 34, and then transmits it to the detection module 60. The detection module 60 receives the echo signal and the local oscillation light outputted from the detection port 34, thereby generating a wind speed signal of the target to be measured.

[0075] As the single pulse energy increases, the pulse peak power increases and the stimulated Brillouin scattering (SBS) effect intensifies, which intensifies the pulse trailing edge jitter and affects the wind measurement accuracy. The stimulated Brillouin scattering threshold (SBS threshold, SBST) is shown in formula (7): (7)

[0076] in is the stimulated Brillouin scattering threshold and is the pulse peak power. is the fiber mode field area, is the Brillouin gain value. is the effective fiber length. For gain fiber, this value is the path integral, and for ordinary transmission fiber, this value is equivalent to the physical length of the transmission fiber Optimizing the gain fiber length to reduce SBS will also affect the amplifier gain. Therefore, from an engineering perspective, the most effective way to suppress SBS is to reduce the length of the transmission fiber. .

[0077] Exemplarily, the reflection module 44 also includes a dual-core pin, which includes: a first pin port 31, which receives the second laser and transmits the second laser to the reflection module 44; and a second pin port 32, which is connected to the erbium-doped optical fiber 42, for receiving the fourth signal light, and transmitting the fourth signal light to the reflection module 44; and is also used to receive the second laser and the fourth signal light reflected by the reflection module 44, and transmit the second laser and the fourth signal light to the erbium-doped optical fiber 42.

[0078] The backward pumped double-pass amplification optical path of the present application facilitates the integration of wavelength division multiplexers and Faraday rotator optical devices. Taking into account the device loss rate and the operability of the fusion splicer, we assume that the length of each pigtail of the optical device is 10 cm. Taking into account the double-pass optical path, after the device is integrated, the saved optical path length is 40 cm. The 980 pump light, that is, the second laser, passes through the first port of the pin and is focused onto the color filter 442 through the self-focusing collimator. The color filter 442 reflects the second laser, that is, the pump light, to the common end (COM), that is, the second port of the pin. The signal light is input through the COM end, and after being reflected by the Faraday rotator and the reflector, it returns to the common end for output along the original path.

[0079] In this embodiment, the second port 32 of the hybrid optical ring module 30 and the Faraday rotation unit 4431 form a polarization switch, which can effectively isolate the single optical path stray light inside the acousto-optic modulator. By adopting a double-pass structure of a polarization beam splitter and a Faraday rotator, the polarization state of the signal light with a second frequency shift changes by 90° after passing through the Faraday rotator, while the stray light with a single frequency shift caused by the internal surface reflection of the acousto-optic modulator does not pass through the Faraday rotator, and its polarization state differs by 90° from the signal light. Therefore, the signal light and the stray light are separated by the polarization separation principle, and the pulse envelope modulation problem caused by the interference between the two is avoided; and by making the pump light, i.e., the second laser, and the first laser transmit in the opposite direction, the integration of the wavelength division multiplexer and the Faraday rotator is facilitated, the length of the transmission optical fiber is shortened, and the nonlinear effect caused by SBS is reduced.

[0080] In one embodiment, the first port 31, the second port 32, the third port 33 and the detection port 34 of the hybrid optical ring module 30 all use polarization-maintaining optical fibers, the slow axis of the polarization-maintaining optical fiber of the second port 32 is aligned with the slow axis of the polarization-maintaining optical fiber of the first port 31, the fast axis of the polarization-maintaining optical fiber of the third port 33 is aligned with the slow axis of the polarization-maintaining optical fiber of the second port 32, and the slow axis of the polarization-maintaining optical fiber of the detection port 34 is aligned with the slow axis of the polarization-maintaining optical fiber of the third port 33.

[0081] For example, please refer to Figure 4 , Figure 4 Schematic diagram of a hybrid optical ring module in an embodiment. The first port 31, the second port 32, the third port 33 and the detection port 34 of the hybrid optical ring module 30 all use polarization-maintaining fibers, the slow axis of the polarization-maintaining fiber of the second port 32 is aligned with the slow axis of the polarization-maintaining fiber of the first port 31, the fast axis of the polarization-maintaining fiber of the third port 33 is aligned with the slow axis of the polarization-maintaining fiber of the second port 32, and the slow axis of the polarization-maintaining fiber of the detection port 34 is aligned with the slow axis of the polarization-maintaining fiber of the third port 33.

[0082] In one embodiment, the polarization state of the first signal light output by the beam splitter 20 is input along the slow axis direction of the first port 31 of the hybrid light ring module 30, and then output to the acousto-optic module 41 along the slow axis direction of the second port 32. After being chopped and frequency-shifted by the acousto-optic module 41, it is amplified by the erbium-doped fiber 42, passes through the lens 441 and the color filter 442 to reach the polarization rotation unit 443 and then reflects back to the erbium-doped fiber 42. At this time, the polarization state changes by 90° and is transmitted along the fast axis of the polarization-maintaining fiber. After secondary amplification and a second pass through the acousto-optic module 41, it is transmitted to the hybrid light ring module 30 along the fast axis direction of the second port 32, and then output from the third port 33. After passing through the rotating shaft, it is output along the slow axis of the third port 33, and then emitted into the atmosphere through the processing module 50. Ignoring the atmospheric depolarization effect, the polarization state of the scattered return light received by the processing module 50 is still transmitted along the slow axis of the polarization-maintaining optical fiber, reaches the third port 33 of the hybrid optical ring module 30 after passing through the optical switch, and then is transmitted to the hybrid optical ring module 30 along the slow axis direction of the third port 33, and then is output to the detection module 60 along the slow axis direction of the detection port 34.

[0083] When the laser passes through the gain fiber for the second time, the energy of the single pulse is further amplified, and the SBS effect is aggravated. At this time, the transmission fiber length after output from the gain fiber has a greater impact. In this embodiment, by matching the polarization beam splitter such as PBS and the four ports of the hybrid optical ring module 30, and designing the transmission characteristics of each port, the polarization separation effect of PBS+Faraday rotator is guaranteed, thereby saving 20cm of fiber length and reducing the SBS effect.

[0084] In one embodiment, the processing module 50 includes: an optical switch 51, which is used to switch the transmission channel and the receiving channel of the second signal light; a telescope 52, which receives the second signal light through the transmission channel opened by the optical switch 51 and transmits the second signal light to the target to be measured, receives the echo signal reflected back by the target to be measured, and transmits the echo signal to the receiving channel switched by the optical switch 51.

[0085] Exemplarily, the first laser emitted by the first light source 10, such as a seed laser, is divided into two beams by the beam splitter 20, one beam is used as the local oscillator light, connected to the detection module 60, and the other beam is the first signal light, which is transmitted to the first port 31 of the hybrid light ring module 30, such as a four-port optical circulator, output from the second port 32, and transmitted to the adjustment module 40. The adjustment module 40 performs two frequency shifts, chops, and amplifies the incident first laser to become a pulse light of the second signal light, and then reflects it back to the second port 32. After that, the second signal light passes through the third port 33, passes through the optical switch 51, and is emitted into the atmosphere through the telescope 52. After the scattered light signal carrying the Doppler frequency shift information, that is, the echo signal, is received by the telescope 52, the echo signal is transmitted to the third port 33 of the hybrid light ring module 30, and then emitted from the detection port 34, and then transmitted to the detection module 60. The detection module 60 receives the echo signal and the local oscillator light output by the detection port 34, thereby generating a wind speed signal of the target to be measured.

[0086] Optionally, the processing module may be a time-division transceiver module, which first switches the second signal light by time division using an optical switch, then transmits the second signal light through a telescope, and then receives an echo signal through the time-division transceiver module.

[0087] In one embodiment, the detection module 60 includes: a coupler 61 for coupling the echo signal and the local oscillator light to obtain a coupled light signal; a balanced detector 62 for receiving the coupled light signal, beating the coupled light signal, and converting the coupled light signal after beating into an electrical signal.

[0088] Exemplarily, the coupler 61 can be a 50 / 50 optical coupler. When coherent detection is possible, the coherent laser signal and the local oscillator signal are incident on the photosensitive surface of the balanced detector 62 together under the condition of satisfying wavefront matching, generating a beat frequency or coherent superposition, so that the output electrical signal of the balanced detector 62 is proportional to the square of the sum of the echo signal (backscattered signal light) and the local oscillator light.

[0089] Furthermore, the slow axis of the detection port 34 of the hybrid optical ring module 30 and the slow axis of the local oscillator light of the beam splitter 20 are respectively connected to the slow axis of the input end of the coupler 61, such as a 50 / 50 optical coupler, and the signal light and the local oscillator light are both transmitted along the slow axis of the input end of the 50 / 50 optical coupler, and the vibration directions of the two are consistent, thereby ensuring the coherence efficiency of the beat frequency of the subsequent local oscillator light and the echo signal scattered by the aerosol surface.

[0090] Based on the same inventive concept, the embodiment of the present application also provides a wind measurement method using a wind laser radar. The solution provided by the method is similar to the solution described in the above wind laser radar. Therefore, the specific limitations of the wind measurement method embodiments of one or more wind laser radars provided below can be found in the above limitations on wind laser radars, which will not be repeated here. Figure 5 , Figure 5 FIG. 1 is a flow chart of a method for measuring wind using a wind laser radar in an embodiment, the method comprising:

[0091] Step 502, controlling a first light source to emit a first laser with a first wavelength, the first laser being split into a local oscillator light and a first signal light by a beam splitter; the first signal light is transmitted to a second port of the hybrid optical ring module through a first port of the hybrid optical ring module, and outputted from the second port.

[0092] Step 504: the control and adjustment module receives the first signal light from the second port, performs two frequency modulations, two pulse modulations, and two power amplifications on the first signal light to obtain a second signal light; the second signal light is incident on the hybrid optical ring module through the second port, and is output from the third port of the hybrid optical ring module.

[0093] Step 506, receiving the second signal light from the third port through the processing module, emitting the second signal light to the target to be measured, and receiving the echo signal reflected back by the target to be measured; the echo signal is incident on the hybrid optical ring module through the third port, and is output from the detection port of the hybrid optical ring module.

[0094] Step 508: The detection module receives the echo signal and the local oscillation light outputted from the detection port, thereby generating a wind speed signal of the target to be detected.

[0095] In this embodiment, by using a hybrid optical ring module and an adjustment module in coordination, the signal light of the target to be detected can be frequency modulated twice, pulse modulated twice, and power amplified twice. The hybrid optical ring module design can reduce the number of passive optical devices, improve the integration of the laser radar, and reduce the additional insertion loss.

[0096] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0097] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0098] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A wind laser radar, characterized in that: The laser radar comprises: A first light source, wherein the first light source emits a first laser having a first wavelength; A beam splitter, receiving the first laser, and splitting the first laser into a local oscillator light and a first signal light; A hybrid optical ring module, comprising a first port and a second port; the hybrid optical ring module receives the first signal light through the first port and outputs the first signal light from the second port; an adjustment module, receiving the first signal light from the second port, and being used to perform two frequency modulations, two pulse modulations, and two power amplifications on the first signal light to obtain a second signal light; the hybrid light ring module further includes a third port, the second port of the hybrid light ring module further receives the second signal light, and outputs the second signal light from the third port; a processing module, receiving the second signal light from the third port, emitting the second signal light to the target to be measured, and receiving the echo signal reflected by the target to be measured; the hybrid optical ring module also includes a detection port, the third port of the hybrid optical ring module also receives the echo signal, and transmits the echo signal to the detection port; The detection module receives the echo signal and the local oscillation light output by the detection port, thereby generating a wind speed signal of the target to be detected.

2. The laser radar according to claim 1, characterized in that: The adjustment module comprises: an acousto-optic module, receiving the first signal light, and performing frequency modulation and pulse modulation on the first signal light to obtain a third signal light; a second light source, the second light source emitting a second laser having a second wavelength; an erbium-doped optical fiber, receiving and transmitting the third signal light and the second laser, wherein the third signal light is transmitted and amplified along a first direction in the erbium-doped optical fiber under the action of the second laser to obtain a fourth signal light; A reflection module receives the fourth signal light and the second laser, and reflects the fourth signal light and the second laser back to the erbium-doped optical fiber; the fourth signal light is transmitted and amplified again in the erbium-doped optical fiber along the second direction under the action of the second laser, and is incident on the acousto-optic module again, and is frequency modulated and pulse modulated by the acousto-optic module to obtain the second signal light; the second direction is opposite to the first direction.

3. The laser radar according to claim 2, characterized in that: The reflection module comprises: a lens, receiving the fourth signal light and the second laser, and adjusting the fourth signal light and the second laser; a color filter, receiving the fourth signal light and the second laser regulated by the lens, reflecting the second laser and transmitting the fourth signal light; the second laser is reflected to the lens, regulated again by the lens and incident on the erbium-doped optical fiber; The polarization rotation unit receives the fourth signal light, rotates the polarization direction of the fourth signal light by 90 degrees, and then reflects it to the color filter; after the polarization direction of the fourth signal light is rotated by 90 degrees, it passes through the color filter and the lens again and is incident on the erbium-doped optical fiber.

4. The laser radar according to claim 3, characterized in that: The hybrid optical ring module also includes a polarization beam splitter; the first signal light is received through the first port, deflected to the second port via the polarization beam splitter, and the first signal light is output from the second port; the second port of the hybrid optical ring module also receives the second signal light, the second signal light is deflected to the third port via the polarization beam splitter, and the second signal light is output from the third port.

5. The laser radar according to claim 2, characterized in that: The repetition frequency of the first laser is between 1 kHz and 15 kHz.

6. The laser radar according to claim 2, characterized in that: The repetition frequency of the first laser is 10 kHz.

7. The laser radar according to claim 3, characterized in that: The polarization rotation unit comprises: A Faraday rotation unit, configured to receive the fourth signal light and rotate the polarization direction of the fourth signal light by 45 degrees under the action of a magnetic field; A reflector receives the fourth signal light with a polarization direction rotated by 45 degrees, and reflects the fourth signal light with a polarization direction rotated by 45 degrees back to the Faraday rotation unit; the fourth signal light with a polarization direction rotated by 45 degrees passes through the Faraday rotation unit again, and the polarization direction is rotated by 45 degrees again before being incident on the color filter.

8. The laser radar according to claim 7, characterized in that: The second laser is transmitted along a second direction.

9. The laser radar according to claim 1, characterized in that: The first port, the second port, the third port and the detection port of the hybrid optical ring module all use polarization-maintaining optical fibers, the slow axis of the polarization-maintaining optical fiber of the second port is aligned with the slow axis of the polarization-maintaining optical fiber of the first port, the fast axis of the polarization-maintaining optical fiber of the third port is aligned with the slow axis of the polarization-maintaining optical fiber of the second port, and the slow axis of the polarization-maintaining optical fiber of the detection port is aligned with the slow axis of the polarization-maintaining optical fiber of the third port.

10. The laser radar according to claim 1, characterized in that: The processing modules include: An optical switch, used for switching a transmitting channel and a receiving channel of the second signal light; The telescope receives the second signal light passing through the transmitting channel opened by the optical switch and transmits the second signal light to the target to be measured, receives the echo signal reflected by the target to be measured, and transmits the echo signal to the receiving channel switched by the optical switch.

11. The laser radar according to claim 1, characterized in that: The detection module comprises: A coupler, used for coupling the echo signal and the local oscillator light to obtain a coupled optical signal; The balanced detector receives the coupled optical signal, performs beat frequency on the coupled optical signal, and converts the coupled optical signal after the beat frequency into an electrical signal.

12. A method for measuring wind using a wind laser radar, characterized in that: The method comprises: Controlling the first light source to emit a first laser with a first wavelength, wherein the first laser is split into a local oscillator light and a first signal light by a beam splitter; the first signal light is transmitted to the second port of the hybrid light ring module through the first port of the hybrid light ring module, and is output from the second port; The control and adjustment module receives the first signal light from the second port, performs two frequency modulations, two pulse modulations, and two power amplifications on the first signal light to obtain a second signal light; the second signal light is incident on the hybrid light ring module through the second port, and is output from the third port of the hybrid light ring module; receiving the second signal light from the third port through the processing module, emitting the second signal light to the target to be measured, and receiving the echo signal reflected by the target to be measured; the echo signal is incident on the hybrid optical ring module through the third port, and is output from the detection port of the hybrid optical ring module; The detection module receives the echo signal and the local oscillation light output by the detection port, thereby generating a wind speed signal of the target to be detected.

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