Rayleigh doppler temperature measurement and wind measurement lidar

Abstract

A Rayleigh Doppler temperature measurement and wind measurement LiDAR, comprising a laser emitter (100), a frequency calibration device (200), and a laser receiver (300). The laser emitter (100) comprises a seed light generating device (110), a pulsed laser (120), and a laser emission coupling unit (130); the seed light generating device (110) is used for generating first seed light and second seed light under the control of a control voltage signal, wherein the first seed light comprises sub-seed light of three different frequencies in a time sequence; the pulsed laser (120) outputs first pulsed laser light when the first seed light is injected into the pulsed laser (120); the laser emission coupling unit (130) is used for generating emission laser light emitted to the atmospheric environment and second pulsed laser light on the basis of the first pulsed laser light; the frequency calibration device (200) is used for outputting the control voltage signal and a voltage level signal on the basis of second seed light and the second pulsed laser light; and the laser receiver (300) is used for measuring both the wind speed and temperature in the atmospheric environment on the basis of a backscattered echo signal and the voltage level signal.

Description

A Rayleigh Doppler temperature and wind measurement lidar Technical Field

[0001] The present disclosure relates to the field of laser radar, and more specifically, to a Rayleigh Doppler temperature and wind measurement laser radar. Background Art

[0002] Detection of the near-space environment (20-100 km) is of vital importance to changes in Earth's atmospheric environment, human aerospace activities, and the design and flight control of spacecraft. In recent years, the detection of wind fields, density, and temperature in near-space has received increasing attention from major countries. Currently, Rayleigh lidar is commonly used for temperature and density detection in the stratosphere-mesosphere region (30-70 km). However, existing Rayleigh lidar inversions of atmospheric density and temperature require density and temperature reference points. During wind speed inversion, temperature inversion errors can also cause wind speed measurement errors.

[0003] Summary of the Invention

[0004] In view of this, an embodiment of the present disclosure provides a Rayleigh Doppler temperature and wind measurement laser radar, comprising:

[0005] Laser transmitter, including:

[0006] A seed light generating device, configured to generate a first seed light and a second seed light under the control of a control voltage signal, wherein the first seed light and the second seed light each include sub-seed lights of three different frequencies in time sequence;

[0007] a pulse laser that outputs a first pulse laser when the first seed light is injected into the pulse laser, wherein the first pulse laser includes three sub-pulse lasers of different frequencies;

[0008] a laser emission coupling unit, configured to generate an emission laser and a second pulse laser emitted into the atmospheric environment based on the first pulse laser, wherein the emission laser interacts with molecules in the atmospheric environment to generate a backscattered echo signal;

[0009] a frequency calibration device, configured to output the control voltage signal and the voltage level signal according to the second seed light and the second pulsed laser, wherein the control voltage signal is used to lock the laser frequency of the seed light;

[0010] The laser receiver is used to receive the backscattered echo signal and simultaneously measure the wind speed and temperature in the atmospheric environment based on the backscattered echo signal and the voltage level signal.

[0011] According to an embodiment of the present disclosure, the seed light generating device includes:

[0012] A seed light laser, configured to output a continuous laser with a narrow linewidth under the control of the control voltage signal;

[0013] an optical fiber beam splitter, configured to split the continuous laser light into a first laser light and a second laser light, wherein the power of the first laser light is greater than the power of the second laser light, and the second laser light represents the second seed light;

[0014] The optical fiber acousto-optic frequency shifter is used to generate the first seed light according to the first laser.

[0015] According to an embodiment of the present disclosure, the laser emission coupling unit includes:

[0016] A beam expander, used to adjust the spot and divergence angle of the first pulsed laser to obtain a third laser;

[0017] The first beam splitter is used to split the third laser into the emission laser and the second pulse laser.

[0018] According to an embodiment of the present disclosure, the laser emission coupling unit further includes:

[0019] The transmitting antenna is used to transmit the above-mentioned transmitting laser into the above-mentioned atmospheric environment.

[0020] According to an embodiment of the present disclosure, the frequency calibration device includes:

[0021] a frequency doubler, configured to perform frequency doubling processing on the second seed light to obtain seed frequency-doubled light;

[0022] a frequency calibrator, configured to generate a first electrical signal and a second electrical signal based on the second pulsed laser and the seed frequency-doubled light;

[0023] a feedback circuit, configured to generate the control voltage signal according to the first electrical signal;

[0024] An integrator is configured to generate the voltage level signal according to the second electrical signal.

[0025] According to an embodiment of the present disclosure, the frequency calibrator includes:

[0026] The first iodine molecular cell is used for:

[0027] processing the seed frequency-doubled light using the absorption spectrum of iodine molecules to obtain processed seed frequency-doubled light;

[0028] processing the second pulse laser using the absorption spectrum of iodine molecules to obtain a processed second pulse laser;

[0029] a first photodiode, configured to amplify and perform photoelectric conversion on the processed seed frequency-doubled light to obtain the first electrical signal;

[0030] a second photodiode, configured to perform photoelectric conversion on the processed second pulse laser to obtain the second electrical signal;

[0031] The voltage level signal is used to lock the frequency of the seed light and monitor the frequency difference between the first pulse laser and the first seed light to correct detection errors.

[0032] According to an embodiment of the present disclosure, the laser receiver includes:

[0033] A telescope for receiving the backscattered echo signal returned by the atmospheric environment;

[0034] a signal processing device for generating a quasi-parallel light beam based on the backscattered echo signal;

[0035] an iodine molecule processing device, configured to generate a reference signal and a target signal based on the quasi-parallel light beam;

[0036] A computing processor is used to simultaneously measure the wind speed and temperature in the atmospheric environment according to the reference signal, the target signal and the voltage level signal.

[0037] According to an embodiment of the present disclosure, the signal processing device includes:

[0038] A chopper disk is used to suppress the near-field strong echo signal in the scattered echo signal under the drive of the motor to obtain a synchronous main signal;

[0039] The collimating lens is used to collimate the above-mentioned synchronous main signal into the above-mentioned quasi-parallel light beam.

[0040] According to an embodiment of the present disclosure, the signal processing device further includes:

[0041] The filter is used to filter the background light signal in the quasi-parallel light beam to obtain a filtered quasi-parallel light beam, so as to process the filtered quasi-parallel light beam using the iodine molecule processing device.

[0042] According to an embodiment of the present disclosure, the iodine molecule processing device includes:

[0043] a second beam splitter, configured to split the quasi-parallel light beam into a first light signal and a second light signal;

[0044] a first photomultiplier tube, configured to perform photoelectric conversion on the first optical signal to obtain a first electrical pulse signal, wherein the first electrical pulse signal represents the reference signal;

[0045] a second iodine molecule pool, configured to absorb the second optical signal to obtain a target echo signal;

[0046] The second photomultiplier tube is used to perform photoelectric conversion processing on the target echo signal to obtain the target signal.

[0047] According to an embodiment of the present disclosure, a seed light generating device generates a first seed light and a second seed light comprising sub-seed lights of three different frequencies in a temporal sequence. A pulsed laser generates a first pulse laser comprising sub-pulse lasers of three different frequencies by time-sharing injection of the first seed light. The pulse lasers are input into a laser emission coupling unit to generate an emission laser and a second pulse laser for emission into the atmosphere. Simultaneously, a frequency calibration device outputs a control voltage signal and a voltage level signal based on the second seed light and the second pulse laser to control the seed light generating device, thereby enabling a laser receiver to simultaneously measure wind speed and temperature in the atmosphere using backscattered echo signals and voltage level signals received from the atmosphere. Because the Rayleigh Doppler temperature and wind measurement lidar of the present disclosure no longer relies on density and temperature reference points, but instead uses the first seed light comprising sub-seed lights of three different frequencies in a temporal sequence as the system light source to achieve absolute temperature and wind speed measurement, it avoids temperature measurement errors caused by reliance on temperature and density reference points, as well as single-frequency laser wind measurement errors caused by temperature errors. This significantly improves the accuracy and sensitivity of the Rayleigh Doppler temperature and wind measurement lidar in temperature and wind speed measurement.

[0048] By using a time-sharing sequence to emit 532nm and multiple frequencies of lasers near it, the corresponding echo signal intensities are received respectively, and the Doppler broadening and frequency shift information caused by wind speed is directly converted into the signal intensities of multiple frequencies, and the temperature and information are inverted according to the echo signal intensities. Since the present disclosure can technically realize the absolute measurement of temperature in the stratosphere-mesosphere region (30-70km), it no longer depends on the density reference point and the temperature reference point; a three-frequency laser is used as the system light source to realize the absolute measurement of temperature at the same time, and the influence of temperature on the spectrum line is considered at the same time in the wind speed calculation process, which greatly improves the accuracy and sensitivity of the Rayleigh Doppler lidar wind and temperature measurement. Therefore, the temperature measurement error caused by the temperature reference point and the density reference point, as well as the single-frequency laser wind measurement error caused by the temperature error, can be solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] FIG1 shows a framework diagram of a Rayleigh Doppler temperature and wind measurement laser radar according to an embodiment of the present disclosure;

[0050] FIG2 shows a framework diagram of a seed light generating device according to an embodiment of the present disclosure;

[0051] FIG3 shows a framework diagram of a laser emission coupling unit according to an embodiment of the present disclosure;

[0052] FIG4 shows a framework diagram of a frequency calibration device according to an embodiment of the present disclosure;

[0053] FIG5 shows a framework diagram of a frequency calibrator according to an embodiment of the present disclosure;

[0054] FIG6 shows a framework diagram of a laser receiver according to an embodiment of the present disclosure;

[0055] FIG7 shows a framework diagram of a signal processing device according to an embodiment of the present disclosure;

[0056] FIG8 shows a framework diagram of an iodine molecule processing apparatus according to an embodiment of the present disclosure;

[0057] FIG9 shows a structural flow chart of a Rayleigh Doppler temperature and wind measurement lidar according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0058] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0059] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise," "include," etc. used herein indicate the presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0060] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0061] When expressions such as "at least one of A, B and C, etc." are used, they should generally be interpreted in accordance with the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0062] Rayleigh lidar is commonly used for temperature and density detection in the stratosphere-mesosphere region (30-70km). Existing Rayleigh lidars require density and temperature reference points to invert atmospheric density and temperature. Deviations from the density and temperature references will introduce errors in the temperature calculation, making it impossible to achieve absolute temperature measurement. Existing Rayleigh Doppler lidars only emit single-frequency lasers. The receiver uses an interferometer standard or an iodine molecule absorption cell discriminator to identify the Doppler frequency shift information of the Rayleigh echo signal caused by atmospheric wind speed. The single-frequency echo signal carries both temperature and wind speed information. During the wind speed inversion process, the temperature must be calculated first using the static equilibrium equation and the ideal gas state equation, and then the wind speed is calculated. Therefore, temperature inversion errors will also cause wind speed measurement errors.

[0063] In view of this, an embodiment of the present disclosure provides a Rayleigh Doppler temperature and wind measurement laser radar. The laser radar includes a laser transmitter, including: a seed light generating device for generating a first seed light and a second seed light under the control of a control voltage signal, wherein the first seed light and the second seed light each include sub-seed lights of three different frequencies in time sequence; a pulse laser for outputting a first pulse laser when the first seed light is injected into the pulse laser, wherein the first pulse laser includes sub-pulse lasers of three different frequencies; a laser emission coupling unit for generating a transmitting laser and a second pulse laser emitted into the atmospheric environment based on the first pulse laser, wherein the transmitting laser interacts with molecules in the atmospheric environment to generate a backscattered echo signal; a frequency calibration device for outputting a control voltage signal and a voltage level signal based on the second seed light and the second pulse laser, wherein the control voltage signal is used to lock the laser frequency of the seed light; and a laser receiver for simultaneously measuring the wind speed and temperature in the atmospheric environment based on the backscattered echo signal and the voltage level signal.

[0064] FIG1 shows a framework diagram of a Rayleigh Doppler temperature and wind measurement lidar according to an embodiment of the present disclosure.

[0065] As shown in Figure 1, the Rayleigh Doppler temperature and wind measurement lidar includes:

[0066] The laser transmitter 100 includes: a seed light generating device 110, which is used to generate a first seed light and a second seed light under the control of a control voltage signal, wherein the first seed light and the second seed light each include three sub-seed lights of different frequencies in time sequence; a pulse laser 120, which outputs a first pulse laser when the first seed light is injected into the pulse laser 120, wherein the first pulse laser includes three sub-pulse lasers of different frequencies; a laser emission coupling unit 130, which is used to generate an emission laser and a second pulse laser emitted into the atmospheric environment based on the first pulse laser, wherein the emission laser interacts with molecules in the atmospheric environment to generate a backscattered echo signal.

[0067] The frequency calibration device 200 is configured to output a control voltage signal and a voltage level signal according to the second seed light and the second pulsed laser, wherein the control voltage signal is used to lock the laser frequency of the seed light;

[0068] The laser receiver 300 is configured to receive the backscattered echo signal and simultaneously measure the wind speed and temperature in the atmospheric environment based on the backscattered echo signal and the voltage level signal.

[0069] According to the embodiment of the present disclosure, the pulse laser 120 can be a flash lamp pumped laser or a diode pumped laser. The type of the pulse laser 120 disclosed in the present disclosure is not limited, and those skilled in the art can choose according to actual needs. In one embodiment, the fundamental frequency output of the pulse laser 120 is a 1064.4nm first pulse laser, which outputs a 532.2nm first pulse laser after frequency doubling. In the case of time-sharing injection of the first seed light including three sub-seed lights of different frequencies in the timing sequence output by the seed light generating device 110, the frequency of the output narrow line width is v 532 、v 532 +2f1 and v 532 -2f2 is the first pulse laser of three sub-pulse lasers with different frequencies of 532.2nm.

[0070] According to the embodiments of the present disclosure, the Rayleigh Doppler temperature and wind measurement lidar of the present disclosure can technically realize the absolute measurement of temperature and wind speed in the stratosphere-mesosphere region (30-70km), no longer relying on density reference points and temperature reference points, and simultaneously considering the influence of temperature on the spectrum line in the calculation process of wind speed and temperature.

[0071] FIG2 shows a framework diagram of a seed light generating device according to an embodiment of the present disclosure.

[0072] According to an embodiment of the present disclosure, the seed light generating device 100 includes: a seed light laser 111, which is used to output a continuous laser with a narrowband linewidth under the control of a control voltage signal; a fiber beam splitter 112, which is used to split the continuous laser into a first laser and a second laser, wherein the power of the first laser is greater than the power of the second laser, and the second laser represents the second seed light; and a fiber acousto-optic frequency shifter 113, which is used to generate three first seed lights of different frequencies based on the first laser.

[0073] According to an embodiment of the present disclosure, the seed light laser 111 is a semiconductor laser that outputs a narrow-band continuous laser of 1064 nm, and the output interface may be an optical fiber port.

[0074] According to an embodiment of the present disclosure, fiber beam splitter 112 is used to split the 1064nm laser output from the seed laser into two output paths. The first laser output has a power of at least 20mW and is used for fiber acousto-optic modulation; the second laser output has a power of at least 10mW and is used to stabilize the laser frequency after frequency doubling. The second laser represents the second seed light.

[0075] According to the embodiment of the present disclosure, the fiber acousto-optic frequency shifter 113 is internally integrated with a switch. The first laser is divided into three paths by the one-to-three switch: one path does not change the seed light frequency, and the output frequency is v 1064 The sub-seed light; one-way frequency shift, the output laser frequency is v 1064 +f1 sub-seed light; the last frequency shift, the output frequency is v 1064 The switching time is controlled by the timing of the LiDAR system and is set to switch once every second. The sub-seed lights of different frequencies are combined into one laser output through the three-in-one switch, which serves as the seed injection laser of pulsed laser 120. This is the first seed light including sub-seed lights of three different frequencies in the timing sequence.

[0076] According to an embodiment of the present disclosure, the seed light laser 111 outputs a continuous laser with a narrow-band linewidth under the control of a control voltage signal, and the continuous laser is divided into a first laser and a second laser through an optical fiber splitter 112, wherein the second laser represents the second seed light input to the frequency calibration device 200; the first laser passes through an optical fiber acousto-optic frequency shifter 113 to generate a first seed light, and the output first seed light is input to the pulse laser 120.

[0077] FIG3 shows a framework diagram of a laser emission coupling unit according to an embodiment of the present disclosure.

[0078] According to an embodiment of the present disclosure, the laser emission coupling unit 130 includes: a beam expander 131 for adjusting the spot and divergence angle of the first pulse laser to obtain a third laser; and a first beam splitter 132 for dividing the third laser into an emission laser and a second pulse laser.

[0079] According to an embodiment of the present disclosure, the beam expander 131 adopts a dual-mirror Galilean structure, with a concave eyepiece and a convex output lens. This is used to improve the divergence angle of the 532.2 nm first pulse laser of the pulsed laser 120 and reduce the beam power density. For example, this increases the size of the laser spot and improves the beam divergence angle to within the receiving field of view of the telescope 310. The type of beam expander 131 disclosed in the present disclosure is not limited, and those skilled in the art can select one based on actual needs.

[0080] According to an embodiment of the present disclosure, the surface of the first beam splitter 132 is coated with a beam splitting film, and the splitting ratio can be 99.5% / 0.5%. The first beam splitter 132 splits the third laser output from the beam expander 131 into two paths: an emitting laser and a second pulsed laser. The emitting laser is used to transmit into the atmospheric environment and interact with molecules in the atmosphere to produce a backscattered echo signal; the second pulsed laser serves as the input of the frequency calibration device 200 and is used to monitor the frequency of the first pulsed laser and detect the frequency difference between the first pulsed laser frequency and the first seed light frequency. The type of the first beam splitter 132 disclosed in the present disclosure is not limited, and those skilled in the art can select it according to actual needs.

[0081] According to an embodiment of the present disclosure, the laser emission coupling unit further includes: a transmitting antenna 133 for emitting the emission laser into the atmospheric environment.

[0082] According to an embodiment of the present disclosure, the transmitting antenna 133 is composed of an optical frame and a 532nm reflective lens, and transmits the transmitting laser output by the first beam splitter 132 into the atmospheric environment.

[0083] According to an embodiment of the present disclosure, the beam expander 131 adjusts the first pulse laser to obtain a third laser; the first beam splitter 132 divides the third laser into an emission laser and a second pulse laser, wherein the emission laser is emitted into the atmospheric environment by the emission antenna 133, and the second pulse laser is input into the frequency calibration device 200.

[0084] FIG4 shows a framework diagram of a frequency calibration device according to an embodiment of the present disclosure.

[0085] According to an embodiment of the present disclosure, the frequency calibration device 200 includes: a frequency multiplier 210 for performing frequency doubling processing on the second seed light to obtain seed frequency-doubled light; a frequency calibrator 220 for generating a first electrical signal and a second electrical signal based on the second pulsed laser and the seed frequency-doubled light; a feedback circuit 230 for generating a control voltage signal based on the first electrical signal; and an integrator 240 for generating a voltage level signal based on the second electrical signal.

[0086] According to an embodiment of the present disclosure, the frequency doubler 210 is made of a periodic lithium niobate PPLN crystal and is used to frequency-double the second seed light of the optical fiber splitter 112 to obtain seed frequency-doubled light. For example, the 1064.4nm continuous second seed light output from one of the optical fiber splitter 112 is frequency-doubled to a continuous seed frequency-doubled light of 532.2nm.

[0087] According to an embodiment of the present disclosure, the frequency calibrator 220 has two inputs. One input is the seed frequency-doubled light, which locks the frequency of the seed light laser through the absorption spectrum of iodine molecules to generate a first electrical signal; the other input is the second pulse laser, which monitors the frequency difference between the first pulse laser and the continuous seed laser, corrects the detection error, and generates a second electrical signal.

[0088] According to an embodiment of the present disclosure, the feedback circuit 230 calculates a control voltage signal based on the first electrical signal output by the frequency calibrator 220 by an internal proportional-integral-differential (PID) controller, and outputs the control voltage signal to the wavelength adjustment module of the seed light laser 111, thereby tracking the laser frequency of the locked seed.

[0089] According to an embodiment of the present disclosure, integrator 240 internally includes a trigger module, a delay adjustment module, a gate width adjustment module, and a high-speed acquisition integration circuit. The trigger module is used to synchronize the laser pulse with the internal acquisition integration circuit; the delay adjustment module is used to adjust the synchronization of the laser pulse and the internal acquisition integration circuit to ensure that the complete pulse signal can be acquired and integrated. The gate width adjustment covers the spectral signal after the absorption of iodine molecules in the first 532.2nm pulse laser output by the frequency calibrator 220, and the gate width setting covers the entire pulse width. The internal acquisition integration circuit is used to generate a voltage level signal from the output second electrical signal and store it in digital form in an internal register.

[0090] According to an embodiment of the present disclosure, the frequency multiplier 210 performs frequency doubling processing on the second seed light output by the laser transmitter 100 to obtain seed frequency-doubled light, and generates a second electrical signal through the frequency calibrator 220; the frequency calibrator 220 generates a first electrical signal for the second pulsed laser output by the laser transmitter 100; the feedback circuit 230 generates a control voltage signal based on the first electrical signal and inputs it back to the laser transmitter 100; the integrator 240 generates a voltage level signal based on the second electrical signal and inputs it to the laser receiver 300.

[0091] FIG5 shows a framework diagram of a frequency calibrator according to an embodiment of the present disclosure.

[0092] According to an embodiment of the present disclosure, the frequency calibrator 220 includes: a first iodine molecule pool 221, which is used to: use the absorption spectrum of iodine molecules to process the seed frequency-doubled light to obtain the processed seed frequency-doubled light; use the absorption spectrum of iodine molecules to process the second pulse laser to obtain the processed second pulse laser; a first photodiode 222, which is used to amplify and perform photoelectric conversion on the processed seed frequency-doubled light to obtain a first electrical signal; a second photodiode 223, which is used to perform photoelectric conversion on the processed second pulse laser to obtain a second electrical signal, wherein the voltage level signal is used to monitor the frequency difference between the first pulse laser and the first seed light to correct the detection error.

[0093] According to an embodiment of the present disclosure, the first photodiode 222 is a photodiode with an amplification function; the second photodiode 223 is a general photodiode.

[0094] FIG6 shows a framework diagram of a laser receiver according to an embodiment of the present disclosure.

[0095] According to an embodiment of the present disclosure, the laser receiver 300 includes: a telescope 310 for receiving a scattered echo signal returned from the atmospheric environment; a signal processing device 320 for generating a quasi-parallel light beam based on the scattered echo signal; an iodine molecule processing device 330 for generating a reference signal and a target signal based on the quasi-parallel light beam; and a computing processor 340 for simultaneously measuring the wind speed and temperature in the atmospheric environment based on the reference signal, the target signal and the voltage level signal.

[0096] According to an embodiment of the present disclosure, the telescope 310 is used to receive three-frequency lasers (v 532 、v 532 +2f1 and v 532 -2f2) and the atmosphere after the atmospheric molecules with the Doppler frequency shift caused by wind speed backscatter echo signal.

[0097] Telescope 310 can use a commonly used Newtonian telescope or Cassegrain telescope to receive atmospheric molecule echo signals. The type of telescope disclosed in the present invention is not limited, and those skilled in the art can choose according to actual needs. The telescope pointing direction can be set to an appropriate direction according to the actual scientific detection needs. For example, if it is necessary to detect latitudinal winds, the telescope can be pointed eastward or westward, and the zenith tilt angle is generally set between 15° and 30°; if it is necessary to detect longitudinal winds, the telescope can be pointed eastward or westward, and the zenith tilt angle is generally set between 15° and 30°; if it is necessary to detect vertical winds, the telescope should be pointed at the zenith. The telescope lens needs to be coated with a high-reflection coating for a wavelength of 532.2nm to ensure the efficiency of receiving echo signals.

[0098] According to an embodiment of the present disclosure, the computing processor 340 includes a photon counting card and various commonly used interfaces, which complete the signal acquisition and component coordinated control functions of the Rayleigh Doppler temperature and wind measurement lidar, and is used to collect and display scattered echo signals and monitor the frequency changes of the emitted laser.

[0099] FIG7 shows a framework diagram of a signal processing apparatus according to an embodiment of the present disclosure.

[0100] According to an embodiment of the present disclosure, the signal processing device 320 includes: a chopping disk 321, which is used to suppress the near-field strong echo signal in the scattered echo signal under the drive of a motor to obtain a synchronous main signal; and a collimating lens 322, which is used to collimate the synchronous main signal into a quasi-parallel light beam.

[0101] According to the embodiments of the present disclosure, a chopper disk is used to suppress strong low-altitude echo signals, ensuring that subsequent detection functions operate within a linear range. The chopper disk is provided with slots, and a high-speed motor drives the disk to rotate at a speed set by the radar system, thereby suppressing strong near-field echo signals from the LiDAR system. Trigger signal generation and reception modules are installed on both sides of the chopper disk to output the synchronized main signal required by the LiDAR system.

[0102] According to an embodiment of the present disclosure, the collimating lens is used to collimate the optical signal of the echo signal received by the telescope after passing through the transmission optical fiber into a quasi-parallel light beam.

[0103] According to an embodiment of the present disclosure, the signal processing device further includes: a filter 323 for filtering the background light signal in the quasi-parallel light beam to obtain a filtered quasi-parallel light beam, so as to use the iodine molecule processing device 330 to process the filtered quasi-parallel light beam.

[0104] According to an embodiment of the present disclosure, the filter 323 can preliminarily filter out the background noise signal in the quasi-parallel light beam to preliminarily suppress the sky background light signal, while the useful 532.2nm echo signal can pass through the filter 323 to obtain a filtered quasi-parallel light beam.

[0105] FIG8 shows a framework diagram of an iodine molecule processing apparatus according to an embodiment of the present disclosure.

[0106] According to an embodiment of the present disclosure, the iodine molecule processing device 330 includes: a second beam splitter 331, used to split the quasi-parallel light beam into a first light signal and a second light signal; a first photomultiplier tube 334, used to perform photoelectric conversion processing on the first light signal to obtain a first electrical pulse signal, wherein the first electrical pulse signal represents a reference signal; a second iodine molecule pool 332, used to perform absorption processing on the second light signal to obtain a target echo signal; and a second photomultiplier tube 333, used to perform photoelectric conversion processing on the target echo signal to obtain a target signal.

[0107] According to the disclosed embodiment, the second beam splitter 331 is used to split the echo signal into two paths: one path for reflected light, with a ratio of 1%, and the other path for transmitted light, with a ratio of 99%. One path, the first optical signal, serves as the reference echo, eliminating jitter in the echo signal itself; the other path, the second optical signal, serves as the primary detection echo signal. The ratio of reflected and transmitted light can be set according to actual needs.

[0108] According to an embodiment of the present disclosure, the first photomultiplier tube 334 is used to convert the first optical signal into a first electrical pulse signal, which serves as a reference signal for normalizing the influence of signal power jitter.

[0109] According to the embodiment of the present disclosure, the second iodine molecule pool 332 transmits the triple-frequency laser (v 532 、v 532 +2f1 and v 532 -2f2) atmospheric echo signal, absorbs the second optical signal to obtain the target echo signal. The absorption strength is related to the echo signal frequency. By adjusting the absorption strength of the three-frequency signal, the frequency shift information caused by wind speed contained in the main detection echo signal is identified.

[0110] According to an embodiment of the present disclosure, the second photomultiplier tube 333 is used to detect the triple-frequency echo signal with Doppler frequency shift caused by the movement of atmospheric molecules with wind speed after being absorbed by the iodine molecule absorption cell, and convert it into a target signal.

[0111] FIG9 shows a structural flow chart of a Rayleigh Doppler temperature and wind measurement lidar according to an embodiment of the present disclosure.

[0112] In a specific embodiment, as shown in FIG9 , a seed light laser 111 outputs a continuous laser with a narrowband linewidth, which is then split into a first laser and a second laser by a fiber beam splitter 112. The first laser is input into a fiber acousto-optic frequency shifter 113 to generate a first seed light and a second seed light comprising sub-seed lights of three different frequencies in time sequence. The second laser, as the second seed light, is input into a frequency multiplier to obtain a seed frequency-doubled light, which is then input into a frequency calibrator 220. After the first seed light is input into the pulse laser 120, a first pulse laser comprising three sub-pulse lasers of different frequencies is output. The first pulse laser passes through a beam expander 131 to obtain a third laser. The third laser passes through a first beam splitter 132 to be divided into an emission laser and a second pulse laser. The emission laser is emitted into the atmosphere via a transmitting antenna 133; the second pulse laser is input into the frequency calibrator 220. The seed frequency-doubled light and the second pulsed laser pass through the frequency calibrator 220 to obtain a first electrical signal. The first electrical signal generates a control voltage signal through the feedback circuit 230 and outputs it to the wavelength adjustment module of the seed laser 111, thereby tracking and locking the seed laser frequency. The seed frequency-doubled light passes through the frequency calibrator 220 to obtain a second electrical signal. The second electrical signal generates a voltage level signal through the integrator 240.

[0113] Telescope 310 receives backscattered echo signals from the atmospheric environment and inputs them into chopper disk 321. Chopper disk 321 suppresses strong near-field echo signals in the backscattered echo signals to generate a synchronized main signal. The synchronized main signal passes through collimating lens 322 to produce a quasi-parallel beam, which is filtered by filter 323. The filtered quasi-parallel beam is split into a first optical signal and a second optical signal by second beamsplitter 331. The first optical signal is processed by first photomultiplier tube 334 to produce a first electrical pulse signal, i.e., a reference signal. The second optical signal is processed by second iodine molecular cell 332 to produce a target echo signal, which is then processed by second photomultiplier tube 333 to obtain the target signal.

[0114] The reference signal, target signal and voltage level signal are used by the computer processor 340 to measure the wind speed and / or temperature in the atmospheric environment.

[0115] According to an embodiment of the present disclosure, a seed light generating device generates a first seed light and a second seed light comprising sub-seed lights of three different frequencies in a temporal sequence. A pulsed laser generates a first pulse laser comprising sub-pulse lasers of three different frequencies by time-sharing injection of the first seed light. The pulse lasers are input into a laser emission coupling unit to generate an emission laser and a second pulse laser for emission into the atmosphere. Simultaneously, a frequency calibration device outputs a control voltage signal and a voltage level signal based on the second seed light and the second pulse laser to control the seed light generating device, thereby enabling a laser receiver to simultaneously measure wind speed and temperature in the atmosphere using backscattered echo signals and voltage level signals received from the atmosphere. Because the Rayleigh Doppler temperature and wind measurement lidar of the present disclosure no longer relies on density and temperature reference points, but instead uses the first seed light comprising sub-seed lights of three different frequencies in a temporal sequence as the system light source to achieve absolute temperature and wind speed measurement, it avoids temperature measurement errors caused by reliance on temperature and density reference points, as well as single-frequency laser wind measurement errors caused by temperature errors. This significantly improves the accuracy and sensitivity of the Rayleigh Doppler temperature and wind measurement lidar in temperature and wind speed measurement.

[0116] The embodiments of the present disclosure are described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be used in combination to advantage. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make three substitutions and modifications, all of which should fall within the scope of the present disclosure.

Claims

1. A Rayleigh Doppler temperature and wind measurement laser radar, comprising: Laser transmitter, including: A seed light generating device, used to generate a first seed light and a second seed light under the control of a control voltage signal, wherein the first seed light and the second seed light both include sub-seed lights of three different frequencies in time sequence; a pulse laser, which outputs a first pulse laser when the first seed light is injected into the pulse laser, wherein the first pulse laser includes three sub-pulse lasers with different frequencies; A laser emission coupling unit, configured to generate an emission laser and a second pulse laser emitted to an atmospheric environment according to the first pulse laser, wherein the emission laser interacts with molecules in the atmospheric environment to generate a backscattered echo signal; a frequency calibration device, configured to output the control voltage signal and the voltage level signal according to the second seed light and the second pulsed laser, wherein the control voltage signal is used to lock the laser frequency of the first seed light; The laser receiver is used to receive the backscattered echo signal and simultaneously measure the wind speed and temperature in the atmospheric environment according to the backscattered echo signal and the voltage level signal.

2. The laser radar according to claim 1, wherein: The seed light generating device comprises: A seed light laser, used for outputting a continuous laser with a narrow-band line width under the control of the control voltage signal; an optical fiber beam splitter, used to split the continuous laser into a first laser and a second laser, wherein the power of the first laser is greater than the power of the second laser, and the second laser represents the second seed light; An optical fiber acousto-optic frequency shifter is used to generate the first seed light according to the first laser.

3. The laser radar according to claim 1, wherein: The laser emission coupling unit comprises: A beam expander, used for adjusting the spot and divergence angle of the first pulse laser to obtain a third laser; The first beam splitter is used to split the third laser into the emission laser and the second pulse laser.

4. The laser radar according to claim 3, wherein: The laser emission coupling unit also includes: A transmitting antenna is used to transmit the transmitting laser into the atmospheric environment.

5. The laser radar according to claim 1, wherein: The frequency calibration device comprises: A frequency doubler, used for performing frequency doubling processing on the second seed light to obtain seed frequency-doubled light; A frequency calibrator, used to generate a first electrical signal and a second electrical signal according to the second pulsed laser and the seed frequency-doubled light; a feedback circuit, configured to generate the control voltage signal according to the first electrical signal; An integrator is used to generate the voltage level signal according to the second electrical signal.

6. The laser radar according to claim 5, wherein: The frequency calibrator comprises: The first iodine molecular pool is used for: Processing the seed frequency-doubled light using the absorption spectrum of iodine molecules to obtain processed seed frequency-doubled light; Processing the second pulse laser using the absorption spectrum of iodine molecules to obtain a processed second pulse laser; a first photodiode, used for amplifying and photoelectrically converting the processed seed frequency-doubled light to obtain the first electrical signal; a second photodiode, used for performing photoelectric conversion processing on the processed second pulse laser to obtain the second electrical signal; The voltage level signal is used to monitor the frequency difference between the first pulse laser and the first seed light to correct the detection error.

7. The laser radar according to claim 1, wherein: The laser receiver comprises: A telescope, used for receiving the scattered echo signal returned by the atmospheric environment; A signal processing device, used for generating a quasi-parallel light beam according to the scattered echo signal; an iodine molecule processing device, used for generating a reference signal and a target signal according to the quasi-parallel light beam; A computing processor is used to simultaneously measure the wind speed and temperature in the atmospheric environment according to the reference signal, the target signal and the voltage level signal.

8. The laser radar according to claim 7, wherein: The signal processing device comprises: A chopper disk is used to suppress the near-field strong echo signal in the scattered echo signal under the drive of the motor to obtain a synchronous main signal; A collimating lens is used to collimate the synchronous main signal into the quasi-parallel light beam.

9. The laser radar according to claim 8, wherein: The signal processing device further comprises: The filter is used to filter the background light signal in the quasi-parallel light beam to obtain a filtered quasi-parallel light beam, so as to use the iodine molecule processing device to process the filtered quasi-parallel light beam.

10. The laser radar according to claim 7, wherein: The iodine molecule processing device comprises: A second beam splitter, used for splitting the quasi-parallel light beam into a first light signal and a second light signal; a first photomultiplier tube, configured to perform photoelectric conversion processing on the first optical signal to obtain a first electrical pulse signal, wherein the first electrical pulse signal represents the reference signal; A second iodine molecule pool is used to absorb the second light signal to obtain a target echo signal; The second photomultiplier tube is used to perform photoelectric conversion processing on the target echo signal to obtain the target signal.

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