阅读说明：本技术 一种基于可调谐激光的掩星大气风速廓线测量系统及方法 (Occultation atmosphere wind speed profile measuring system and method based on tunable laser ) 是由 王玉诏 陶宇亮 于 2019-10-28 设计创作，主要内容包括：一种基于可调谐激光的掩星大气风速廓线测量系统及方法,属于激光遥感技术领域。本发明通过两颗卫星构建掩星探测链路,通过发射并接收波长可调谐激光获得大气吸收光谱,以时间为基准得到发射光谱与接收光谱的定量信息,再通过反演手段计算得到大气风速廓线信息。本发明通过激光波长调谐扫描技术,解决了高空大气风速高精度高垂直分辨廓线探测问题；通过优选激光波长,可以覆盖5km以上任意高度；通过控制激光发射能量,可以有效控制和提高探测信噪比和垂直分辨率；通过激光波长调谐扫描,可以在无高精度先验条件、无高精度稳频和控制的前提下自适应的完成运动多普勒频移补偿,有效降低系统研制复杂度和成本。(A occultation atmosphere wind speed profile measuring system and method based on tunable laser belongs to the technical field of laser remote sensing. The invention constructs a occultation detection link through two satellites, obtains an atmospheric absorption spectrum by transmitting and receiving wavelength tunable laser, obtains quantitative information of the transmitted spectrum and the received spectrum by taking time as a reference, and obtains atmospheric wind speed profile information by calculation through an inversion means. The invention solves the problem of high-altitude atmospheric wind speed, high precision and high vertical resolution profile detection by the laser wavelength tuning scanning technology; the laser wavelength is optimized, and the laser can cover any height above 5 km; by controlling the laser emission energy, the detection signal-to-noise ratio and the vertical resolution can be effectively controlled and improved; by laser wavelength tuning scanning, the motion Doppler frequency shift compensation can be completed in a self-adaptive manner on the premise of no high-precision prior condition, no high-precision frequency stabilization and control, and the complexity and cost of system development are effectively reduced.)

1. A occultation atmosphere wind speed profile measuring system based on tunable laser is characterized in that: the device comprises a laser transmitter (1), a laser receiver (2) and a data processing module (3);

the laser transmitter (1) comprises a spectrum laser (4), a laser frequency discriminator (5), a transmitting timer (6) and a transmitting optical system (7); the spectrum laser (4) emits wavelength tuning laser, a first part of the wavelength tuning laser enters the laser frequency discriminator (5), the laser frequency discriminator (5) measures the wavelength and the energy of the wavelength tuning laser, the measured wavelength and the measured energy are sent to the emission timer (6), the emission timer (6) records the time corresponding to the emission wavelength and the energy, and the emission energy and the time data are transmitted to the data processing module (3); the second part of the wavelength tuning laser enters the transmitting optical system (7), enters the earth atmosphere after passing through the transmitting optical system (7) and finally reaches the laser receiver (2);

the laser receiver (2) comprises a receiving optical system (8), a photoelectric detection sampling module (9) and a receiving timer (10); the receiving optical system (8) receives a second part of the wavelength tuning laser, then the second part is sent to the photoelectric detection sampling module (9), the photoelectric detection sampling module (9) measures the energy of the received laser, the measured energy is sent to the receiving timer (10), the receiving timer (10) records the arrival time of the energy, and the received energy and time data are transmitted to the data processing module (3);

the data processing module (3) receives the transmitting energy and time data and the receiving energy and time data, calculates the wind speed at the tangent point height of the light path and the atmosphere in the occultation process, and constructs the wind speed profile by the wind speeds at different tangent point heights.

2. The system and method for measuring the occultation atmosphere wind speed profile based on the tunable laser according to claim 1, wherein: the energy proportion of the first part is not more than 2% of the energy of the wavelength tuning laser, and the energy proportion of the second part is 1-the energy proportion of the first part.

3. The system and method for measuring the occultation atmosphere wind speed profile based on the tunable laser according to claim 1, wherein: the central wavelength of the wavelength tuning laser is positioned at the absorption peak of the tracer molecule, and the adjusting range is not less than 100 times of the line width of the absorption spectrum.

4. The system and method for measuring the occultation atmosphere wind speed profile based on the tunable laser according to claim 1, wherein: the wind speed is

5. The system and method for measuring the occultation atmosphere wind speed profile based on the tunable laser according to claim 4, wherein: the { Δ λ [ ]_wi}＝{λ_xi-λ₀}; wherein λ is_xiIs composed of { P_ri(λ_si-Δλ_di-Δλ_ci) Get the absorption peak position, P, at different tangent point heights_riA column of spectral laser receive energy data.

6. The occultation atmosphere wind profile measuring method realized by the occultation atmosphere wind profile measuring system based on the tunable laser according to claim 1, characterized by comprising the following steps:

the spectrum laser (4) emits wavelength tuning laser, a first part of the wavelength tuning laser enters the laser frequency discriminator (5), the laser frequency discriminator (5) measures the wavelength and the energy of the wavelength tuning laser, the measured wavelength and the measured energy are sent to the emission timer (6), the emission timer (6) records the time corresponding to the emission wavelength and the energy, and the emission wavelength, the energy and the time data are transmitted to the data processing module (3); the second part of the wavelength tuning laser enters the transmitting optical system (7), enters the earth atmosphere after passing through the transmitting optical system (7) and finally reaches the laser receiver (2);

the receiving optical system (8) receives a second part of the wavelength tuning laser, then the second part is sent to the photoelectric detection sampling module (9), the photoelectric detection sampling module (9) measures the energy of the received laser, the measured energy is sent to the receiving timer (10), the receiving timer (10) records the arrival time of the energy, and the received energy and time data are transmitted to the data processing module (3);

the data processing module (3) receives the emission wavelength, the energy and the time data and receives the energy and the time data, calculates the wind speed at the tangent point height of the light path and the atmosphere in the occultation process, and constructs the wind speed profile by the wind speeds at different tangent point heights.

7. A method of masquerading atmospheric wind profile measurement according to claim 6, wherein: the energy proportion of the first part is not more than 2% of the energy of the wavelength tuning laser, and the energy proportion of the second part is 1-the energy proportion of the first part.

8. A method of masquerading atmospheric wind profile measurement according to claim 6, wherein: the central wavelength of the wavelength tuning laser is positioned at the absorption peak of the tracer molecule, and the adjusting range is not less than 100 times of the line width of the absorption spectrum.

9. A method of masquerading atmospheric wind profile measurement according to claim 6, wherein: the wind speed is

10. A occultation atmospheric wind profile measurement method according to claim 9, characterized by: the { Δ λ [ ]_wi}＝{λ_xi-λ₀}; wherein λ is_xiIs composed of { P_ri(λ_si-Δλ_di-Δλ_ci) Get the absorption peak position, P, at different tangent point heights_riA column of spectral laser receive energy data.

Technical Field

The invention relates to a occultation atmosphere wind speed profile measuring system and method based on tunable laser, and belongs to the technical field of laser remote sensing.

Background

The high-altitude atmospheric wind field measurement has important value in multiple fields such as climate, weather and environment, and the satellite remote sensing detection of the high-altitude atmospheric wind field can be realized by means of satellite-borne laser radar, airglow edge detection, fixed-wavelength laser occultation detection and the like at present. However, these approaches still have certain drawbacks and thus do not fully satisfy the practical requirements.

For the laser radar, due to the limitation of atmosphere backscattering signals, the measuring capacity of the satellite-borne coherent laser radar is generally 0-5 km, the measuring capacity of the satellite-borne incoherent laser radar is generally 0-30 km, and the detection capacity of the satellite-borne metal ion fluorescent laser radar is generally 90-110 km. The technical defects of the laser radar are as follows: the method is difficult to measure for wind field satellite-borne laser radars in the range of 30-90 km.

The height range of the airglow, atmospheric radiation and other marginal detection technologies during wind field detection can be extended to 300 km. The defects are as follows: the vertical resolution of the technology is generally 3-10 km in magnitude, 1km vertical resolution detection is difficult to realize, and the difficulty of a spectrum device is high.

A laser occultation atmospheric wind speed measurement technology is provided in foreign countries before and after 2004, and a scheme of double fixed laser wavelengths is adopted. The advantage is that the vertical resolution can be improved to better than 1km by using laser, and the detection height can be expanded by changing the working wavelength. The method has the main defects that large dynamic Doppler frequency shift compensation is required in real time according to different satellite orbit conditions, the development difficulty, the development cost and the development period of a laser emission system are greatly improved, and the technical adaptability is insufficient.

Disclosure of Invention

In order to solve the problem of high-altitude atmospheric wind speed profile laser occultation detection, a occultation atmosphere measurement method based on tunable laser is provided, an occultation detection link is constructed through two satellites, an atmospheric absorption spectrum is obtained by emitting and receiving wavelength tunable laser, quantitative information of an emission spectrum and a receiving spectrum is established by taking time as a reference, and then atmospheric wind speed profile information is obtained by calculation through an inversion means.

The technical solution of the invention is as follows: a occultation atmosphere wind speed profile measuring system based on tunable laser comprises a laser transmitter, a laser receiver and a data processing module;

the laser transmitter comprises a spectrum laser, a laser frequency discriminator, a transmitting timer and a transmitting optical system; the spectrum laser emits wavelength tuning laser, a first part of the wavelength tuning laser enters the laser frequency discriminator, the laser frequency discriminator measures the wavelength and the energy of the wavelength tuning laser, the measured wavelength and the measured energy are sent to the emission timer, the emission timer records the time corresponding to the emission wavelength and the energy, and the emission energy and the time data are transmitted to the data processing module; the second part of the wavelength tuning laser enters the emission optical system, enters the earth atmosphere after passing through the emission optical system and finally reaches the laser receiver;

the laser receiver comprises a receiving optical system, a photoelectric detection sampling module and a receiving timer; the receiving optical system receives a second part of the wavelength tuning laser, then sends the second part to the photoelectric detection sampling module, the photoelectric detection sampling module measures the energy of the received laser, sends the measured energy to the receiving timer, records the arrival time of the energy by the receiving timer, and transmits the received energy and time data to the data processing module;

the data processing module receives the transmitting energy and the time data and receives the energy and the time data, calculates the wind speed on the tangent point height of the light path and the atmosphere in the occultation process, and constructs the wind speed profile by the wind speeds on different tangent point heights.

Further, the energy proportion of the first portion is not more than 2% of the energy of the wavelength tuning laser, and the energy proportion of the second portion is 1-the energy proportion of the first portion.

Further, the central wavelength of the wavelength tuning laser is positioned at the absorption peak of the tracer molecule, and the adjustment range is not less than 100 times of the line width of the absorption spectrum.

Further, the wind speed is

Wherein c is the speed of light, Δ λ_wiWavelength shift, λ, due to wind speed₀Is the standard position of the absorption peak of the received spectrum.

Further, the { Δ λ [ ]_wi}＝{λ_xi-λ₀}; wherein λ is_xiIs composed of { P_ri(λ_si-Δλ_di-Δλ_ci) And obtaining the positions of absorption peaks at different tangent point heights.

The occultation atmosphere wind speed profile measuring method realized by the occultation atmosphere wind speed profile measuring system based on the tunable laser comprises the following steps:

the spectrum laser emits wavelength tuning laser, a first part of the wavelength tuning laser enters the laser frequency discriminator, the laser frequency discriminator measures the wavelength and the energy of the wavelength tuning laser, the measured wavelength and the measured energy are sent to the emission timer, the emission timer records the time corresponding to the emission wavelength and the energy, and the emission wavelength, the energy and the time data are transmitted to the data processing module; the second part of the wavelength tuning laser enters the emission optical system, enters the earth atmosphere after passing through the emission optical system and finally reaches the laser receiver;

the receiving optical system receives a second part of the wavelength tuning laser, then sends the second part to the photoelectric detection sampling module, the photoelectric detection sampling module measures the energy of the received laser, sends the measured energy to the receiving timer, records the arrival time of the energy by the receiving timer, and transmits the received energy and time data to the data processing module;

the data processing module receives the emission wavelength, the energy and the time data and receives the energy and the time data, calculates the wind speed at the tangent point height of the light path and the atmosphere in the occultation process, and constructs the wind speed profile by the wind speeds at different tangent point heights.

Further, the energy proportion of the first portion is not more than 2% of the energy of the wavelength tuning laser, and the energy proportion of the second portion is 1-the energy proportion of the first portion.

Further, the central wavelength of the wavelength tuning laser is positioned at the absorption peak of the tracer molecule, and the adjustment range is not less than 100 times of the line width of the absorption spectrum.

Further, the wind speed isWherein c is the speed of light, Δ λ_wiFor wavelength shifts caused by wind speed, λ₀Is the standard position of the absorption peak of the received spectrum.

Further, the { Δ λ [ ]_wi}＝{λ_xi-λ₀}; wherein λ is_xiIs composed of { P_ri(λ_si-Δλ_di-Δλ_ci) And obtaining the positions of absorption peaks at different tangent point heights.

Compared with the prior art, the invention has the advantages that:

(1) the invention solves the problem of high-altitude atmospheric wind speed, high precision and high vertical resolution profile detection by the laser wavelength tuning scanning technology;

(2) the laser can cover any height above 5km by optimizing the laser wavelength;

(3) by controlling the laser emission energy, the invention can effectively control and improve the detection signal-to-noise ratio and the vertical resolution;

(4) the invention can self-adaptively complete the motion Doppler frequency shift compensation under the premise of no high-precision prior condition and no high-precision frequency stabilization and control by laser wavelength tuning scanning, thereby effectively reducing the complexity and cost of system development.

Drawings

FIG. 1 is a schematic view of a occultation atmospheric wind profile measurement system of the present invention;

FIG. 2 is a diagram illustrating the calibration of laser propagation delay spectra according to the present invention.

Detailed Description

As shown in fig. 1, a occultation atmosphere wind profile measuring system based on tunable laser comprises a laser transmitter 1, a laser receiver 2 and a data processing module 3;

the laser transmitter 1 comprises a spectrum laser 4, a laser frequency discriminator 5, a transmitting timer 6 and a transmitting optical system 7; the spectrum laser 4 emits wavelength tuning laser, a first part of the wavelength tuning laser enters the laser frequency discriminator 5, the laser frequency discriminator 5 measures the wavelength and the energy of the wavelength tuning laser, the measured wavelength and the measured energy are sent to the emission timer 6, the emission timer 6 records the time corresponding to the emission wavelength and the energy, and the emission wavelength, the energy and the time data are transmitted to the data processing module 3; the second part of the wavelength tuning laser enters the transmitting optical system 7, enters the earth atmosphere after passing through the transmitting optical system 7 and finally reaches the laser receiver 2;

the laser receiver 2 comprises a receiving optical system 8, a photoelectric detection sampling module 9 and a receiving timer 10; the receiving optical system 8 receives a second part of the wavelength tuning laser, then sends the second part to the photoelectric detection sampling module 9, the photoelectric detection sampling module 9 measures the energy of the received laser, sends the measured energy to the receiving timer 10, the receiving timer 10 records the arrival time of the energy, and transmits the received energy and time data to the data processing module 3;

the data processing module 3 receives the emission wavelength, the energy and the time data and receives the energy and the time data, calculates the wind speed at the tangent point height of the light path and the atmosphere in the occultation process, and constructs the wind speed profile by the wind speeds at different tangent point heights.

The wind speed calculation method comprises the following steps:

relative motion doppler shift data series [ delta lambda ] calculated from satellite orbit parameters_ci}；

Tangent point height data column { h) calculated by combining satellite orbit parameters with atmosphere model_i}; discrete length of transmission path passing each tangent point height { L (h) calculated by combining satellite orbit parameters with atmosphere model_i,h_j) And j is the serial number of each height layer passed by the designated tangent point height under the layered atmosphere model.

And (5) correcting the optical path delay. According to laser transmission delay time sequence [ delta t ]_diObtaining the corresponding relationship between the received signal and the emission spectrum, as shown in fig. 2:

{P_ri(λ_si-Δλ_di)}；

and (5) satellite Doppler wave shift correction. Doppler shift [ Delta lambda ] according to satellite relative motion_ciObtaining the corresponding relation between the received signal and the spectrum:

{P_ri(λ_si-Δλ_di-Δλ_ci)}；

wind speed is measured. The standard position λ of absorption peak of received spectrum can be known from standard spectrum database (such as HITRAN database)₀From { P }_ri(λ_si-Δλ_di-Δλ_ci) The position of the absorption peak obtained is lambdxTherefore, there is a frequency shift:

{Δλ_wi}＝{λ_xi-λ₀}

thus, the wind speed is obtained:

where c is the speed of light.

Wherein, the spectrum laser emission sampling time data column { t_sgiT is time, s is spectrum, g is emission, i is data sequence number;

spectral laser emission wavelength data string { lambda_siWhere λ represents wavelength;

spectral laser emission energy data column { P_siWhere P represents power;

spectral laser reception time data string { t_riWhere r denotes reception;

spectral laser received energy data column { P_ri}；

Light path delay time data sequence (delta t) of laser transmitter 1 and laser receiver 2_di}；

Wavelength shift data sequence { delta lambda } corresponding to optical path delay of laser transmitter 1 and laser receiver 2_diAnd the energy proportion of the first part is not more than 2% of the energy of the wavelength tuning laser, and the energy proportion of the second part is 1-the energy proportion of the first part.

Preferably, the central wavelength of the wavelength tuning laser is positioned at the absorption peak of the tracer molecule, and the adjustment range is not less than 100 times of the line width of the absorption spectrum.

An embodiment of the present invention.

As shown in fig. 1, the laser occultation detection system mainly comprises a laser transmitter 1, a laser receiver 2 and a data processing module 3.

The spectroscopic laser 4 emits laser light with a center wavelength of 769.89866nm and is scanned by tuning the wavelength in the scanning range of ± 0.05 nm. When the laser is emitted, the emission wavelengths at different moments are obtained through the laser frequency discriminator 5 and the emission timer 6. The laser light emitted by the spectrum laser 4 enters the atmosphere through the emission optical system 7.

At this point it is possible to obtain:

spectral laser emission sampling time data column { t }_sgi}；

Spectral laser emission wavelength data string { lambda_si}；

Spectral laser emission energy data column { P_si}；

The spectrum laser entering the atmosphere through the emission optical system 7 passes through the atmosphere and reaches the receiving optical system 8, and the spectrum laser reaches the photoelectric detection sampling module 9 and the receiving timer 10 after being subjected to spectral filtering by the receiving optical system 8.

In combination with known satellite orbit parameters, one can obtain:

relative motion doppler shift data series [ delta lambda ] calculated from satellite orbit parameters_ci}；

Tangent point height data column { h) calculated by combining satellite orbit parameters with atmosphere model_i}；

Discrete length of transmission path passing each tangent point height { L (h) calculated by combining satellite orbit parameters with atmosphere model_i,h_j)}；

And (5) correcting the optical path delay. According to laser transmission delay time sequence [ delta t ]_diObtaining the corresponding relationship between the received signal and the emission spectrum, as shown in fig. 2:

{P_ri(λ_si-Δλ_di)}；

and (5) satellite Doppler wave shift correction. Doppler shift [ Delta lambda ] according to satellite relative motion_ciObtaining the corresponding relation between the received signal and the spectrum:

{P_ri(λ_si-Δλ_di-Δλ_ci)}；

wind speed is measured. The standard position λ of absorption peak of received spectrum can be known from standard spectrum database (such as HITRAN database)₀From { P }_ri(λ_si-Δλ_di-Δλ_ci) The position of the absorption peak obtained is lambda_xTherefore, there is a frequency shift:

{Δλ_wi}＝{λ_xi-λ₀}

thus, the wind speed is obtained:

where c is the speed of light.

Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.