CN115308774A

CN115308774A - Rayleigh scattering Doppler laser radar system based on four-channel double-pass F-P interferometer

Info

Publication number: CN115308774A
Application number: CN202210990048.6A
Authority: CN
Inventors: 沈法华; 徐华; 朱成云
Original assignee: Yancheng Teachers University
Current assignee: Yancheng Teachers University
Priority date: 2022-08-11
Filing date: 2022-08-11
Publication date: 2022-11-08

Abstract

The invention relates to a direct detection Doppler laser radar system, in particular to a Rayleigh scattering Doppler laser radar system based on a four-channel two-pass F-P interferometer. The method is characterized in that: the emission source adopts 355nm seed injection pulse laser, and the receiving light path mainly comprises four-channel double-pass F-P interferometer, two collimating mirrors, two secondary reflection right-angle prisms, two 1X 2 optical fiber couplers, four beam splitters, six photomultiplier tubes and other devices. The four-channel double-pass F-P interferometer adopts an integrated design, four channels respectively correspond to the F-P interferometer 1, the F-P interferometer 2, the F-P interferometer M and the F-P interferometer L, and the free spectrum spacing is 12GHz. The spectral widths of the F-P interferometer 1 and the F-P interferometer 2 are both 2.2GHz, the spectral peak-to-peak interval of the two is 5.8GHz, the effective light-passing apertures are divided into two parts, and the two parts and the two secondary reflection right-angle prisms form a reciprocating double-path light path respectively, so that incident light beams repeatedly penetrate through the F-P interferometer 1 and the F-P interferometer 2 twice. The spectral widths of the F-P interferometer M and the F-P interferometer L are both 1GHz, the intervals between the spectral peaks of the F-P interferometer M and the F-P interferometer L are 2.9GHz and 2.4GHz, and the F-P interferometer L are both designed into single-pass optical paths and are respectively used for measuring aerosol and measuring and locking the frequency of emitted laser. The emitted laser frequency is locked at the right half waist of the F-P interferometer L, i.e. the position of the spectral peak of the F-P interferometer M or the position of the intersection of the frequency spectra of the F-P interferometer 1 and the F-P interferometer 2. The collimated atmospheric backscattered light is divided into four beams, one beam is used for energy monitoring, and the other three beams are respectively incident to an F-P interferometer M, a double-pass F-P interferometer 1 and a double-pass F-P interferometer 2. The radial wind speed can be obtained by inverting the ratio of the transmittances of the Rayleigh scattering light passing through the double-pass F-P interferometer 1 and the double-pass F-P interferometer 2; the sum of the transmittances can be inverted to obtain the atmospheric temperature. The backscattering ratio obtained by the F-P interferometer M is used for correcting an energy monitoring signal during temperature inversion. Due to the adoption of the technical scheme, compared with the traditional Rayleigh Doppler double-edge technology, the Rayleigh Doppler double-edge technology has the advantages and positive effects that: the interference of rice scattering signals can be strongly inhibited while the measurement sensitivity of wind speed and temperature is remarkably improved, so that the measurement precision of the wind speed and the temperature is improved, and particularly the measurement precision of a wind field and the temperature near low-layer and middle-layer cloud layers or volcanic ash is improved; the optimally designed system parameters give consideration to high and low layer wind fields and temperature measurement, and the high and low layer atmospheric wind fields and temperature can be simultaneously detected with high precision by a single laser radar.

Description

Rayleigh scattering Doppler laser radar system based on four-channel double-pass F-P interferometer

Technical Field

The invention relates to a direct detection Doppler laser radar system, in particular to a Rayleigh scattering Doppler laser radar system based on a four-channel double-pass F-P interferometer.

Background

The atmospheric wind field and the temperature are very important atmospheric parameters. Real-time high-precision and high-space-time resolution atmospheric wind field data are applied to the fields of weather forecast, environment monitoring, wind energy power generation, aerospace and the like, and atmospheric temperature is an important parameter for researching typical problems of greenhouse effect, urban heat island effect, temperature inversion layer, earth gravity wave and the like and is a necessary parameter for measuring relative water vapor influencing atmospheric precipitation and aerosol distribution. The laser radar has obvious advantages in the aspects of detection height, vertical span, spatial resolution, measurement continuity, accuracy and the like, and is one of the most powerful tools for performing atmospheric parameter remote sensing detection at present.

The direct detection Mie-Scattering Doppler laser radar and the coherent detection Doppler laser radar only can detect the atmospheric wind field of the low troposphere by taking aerosol particles in the low-level atmosphere as detection objects, the detection precision depends heavily on the concentration of the aerosol at that time, and the detection precision and the detection distance cannot be well guaranteed under the weather conditions of clear air and little cloud. The concentration of atmospheric molecules is relatively stable and basically not influenced by weather conditions, so that the direct detection Rayleigh scattering Doppler laser radar can theoretically give consideration to the detection of high and low-rise wind fields. However, when detecting the wind field of the lower atmosphere and the middle and upper atmosphere suffering from high-level cloud or volcanic ash, the deviation of the measured wind speed value of the rayleigh scattering doppler laser radar from the actual value is large due to the strong interference of the aerosol meter scattering signal. Aiming at the problem, in the design of a Rayleigh scattering Doppler laser radar system based on a double-F-P interferometer, souprayen and the like and Gentry and the like, the wind speed measurement sensitivity of Rayleigh scattering signals and meter scattering signals under the conditions of set temperature and zero wind speed is the same by optimizing the bandwidth and peak-to-peak interval of the double-F-P interferometer. However, the difference between the actual temperature of the lower atmosphere and the set temperature during parameter design is large, the wind speed is not zero, the concentration of the lower aerosol is large, and the wind speed error caused by directly using a mixed signal of Rayleigh scattering and meter scattering to perform wind speed inversion is still large. In addition, based on the S6 rayleigh-brillouin scattering model, in 2021, applicant proposed a method for inverting the backscattering ratio of the aerosol and the lower wind field by using rayleigh-mie scattering doppler lidar data, but this method requires that the accurate atmospheric temperature profile be known in advance.

The Rayleigh scattering spectrometry is one of important means for detecting the atmospheric temperature below 30km, but when the Rayleigh scattering spectrometry is used for detecting the atmospheric temperature of low-level atmosphere and middle-level atmosphere meeting high-level cloud or volcanic ash, the deviation of a temperature measurement value and an actual value is also large due to strong interference of scattering signals of aerosol rice. Aiming at the problem, in 2005, professor Xin Hua proposes an ultraviolet Rayleigh-meter laser radar for detecting the atmospheric temperature of the troposphere with high precision. The radar adopts a multi-channel F-P etalon, wherein the center of a transmission spectrum of one channel etalon is positioned near the center frequency of a backscattering spectrum and is used for aerosol measurement; the transmission spectrum centers of the other two channel etalons are located at different positions on one side of the backscatter spectrum for temperature measurement, and the backscattered light is passed twice in succession through the two channel etalons to suppress the aerosol scattering signal. The temperature inversion uses aerosol measurements for calibration.

Research shows that a Rayleigh scattering Doppler laser radar system which is based on a four-channel double-pass F-P interferometer and can simultaneously detect the wind field and the temperature of high and low atmosphere at high precision is researched and designed, and reports are not found at present.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the Rayleigh scattering Doppler laser radar system based on the four-channel double-pass F-P interferometer can strongly inhibit interference of a Mie scattering signal, and can be used for simultaneously detecting a high-low atmosphere wind field and temperature with high precision by using the Rayleigh scattering Doppler laser radar based on the four-channel double-pass F-P interferometer.

The technical scheme adopted by the invention for solving the technical problems is as follows: the wind field and temperature measurement principle of the present invention is shown in fig. 1. The free spectral spacings of the F-P interferometer 1, the F-P interferometer 2, the F-P interferometer M and the F-P interferometer L are all 12GHz. The spectral widths of the F-P interferometer 1 and the F-P interferometer 2 are both 2.2GHz, and the interval between the spectral peaks of the two is 5.8GHz; the spectral widths of the F-P interferometer M and the F-P interferometer L are both 1GHz, and the intervals between the spectral peaks of the F-P interferometer M and the F-P interferometer L are respectively 2.9GHz and 2.4GHz. The design parameters of the four-channel double-pass F-P interferometer give consideration to the measurement of high and low-layer wind fields and temperature. Frequency v of emitted laser light ₀ Is locked at the right half waist of the F-P interferometer L, i.e. the position of the spectral peak of the F-P interferometer M or the position of the intersection of the spectra of the two-way F-P interferometer 1 and the F-P interferometer 2. When v is ₀ When the transmittance of the emitted laser light passing through the F-P interferometer L changes, the transmittance of the emitted laser light passing through the F-P interferometer L can be measured and locked v ₀ (relative value). In the measuring process, firstly, the emitted laser beam is vertically incident into the atmosphere for temperature detection, then, the radial wind speed in other directions is measured by three beams or four beams, and vector wind speed synthesis is carried out. Because the vertical wind speed is generally very small, the frequency of the backward scattering light of the vertically emitted light beam is still near the spectral peak of the F-P interferometer M, and the backward scattering ratio can be obtained by using the signals of the vertically emitted backward scattering light before and after the transmission of the signals through the F-P interferometer M for signal correction during temperature inversion. Compared with a single-pass method, the transmittance of the double-pass F-P interferometer 1 and the double-pass F-P interferometer 2 becomes sharper, the contrast is higher, the interference of aerosol meter scattering signals on wind fields and temperature measurement can be strongly inhibited, and the two types of the double-pass F-P interferometer are positioned on two wings of an atmospheric Rayleigh-meter backward scattering spectrum. At a frequency v ₀ Is incident into the atmosphere and encounters atmospheric molecules or aerosol particles with macroscopic motion velocity (i.e. wind velocity). On the one hand, it is backwardThe frequency V of the scattered light is subjected to Doppler frequency shift, the transmittances of Rayleigh scattered light signals passing through the double-pass F-P interferometer 1 and the double-pass F-P interferometer 2 are increased and reduced, the value (relative value) of V can be measured by measuring the transmittance ratio of the Rayleigh scattered light passing through the double-pass F-P interferometer 1 and the double-pass F-P interferometer 2, and further the radial wind speed V is obtained _r ＝(v-v ₀ ) λ/2, where λ is the wavelength of the emitted laser; on the other hand, the rayleigh scattering spectrum width of the rayleigh scattering spectrum will generate a broadening amount proportional to the square root of the atmospheric temperature T, and when the atmospheric temperature T is different, the transmittance of rayleigh scattering light signals passing through the two-way F-P interferometer 1 and the two-way F-P interferometer 2 will be increased or decreased simultaneously, and the atmospheric temperature can be obtained by measuring the sum of the transmittances of rayleigh scattering light passing through the two-way F-P interferometer 1 and the two-way F-P interferometer 2.

Total divergence angle of 2 theta ₀ The transmittance of the monochromatic light with the frequency v entering the one-way F-P interferometer is as follows:

wherein

In the formula: i =1,2,m,l; eta _i ＝T _p，i (1-R _e，i )/(1+R _e，i ) Is the average transmission of the F-P interferometer i, R _e，i Is the effective reflectivity, T, of the i-plate of an F-P interferometer _p，i ＝[1-A/(1-R _i )] ² (1-R _i )(1+R _e，i )/(1+R _i )(1-R _e，i ) Is the peak transmittance, R, of the F-P interferometer i _i And A is the actual reflectivity and absorption loss coefficient of the F-P interferometer i flat plate respectively; v. of _i Is the center frequency of the F-P interferometer i; v. of _FSR Is the free spectral spacing of the F-P interferometer i.

Assuming that the emission laser spectrum is a gaussian spectrum with a narrow bandwidth, the mie and rayleigh backscattering spectral lines are both approximately gaussian distributed and can be expressed as

In the formula: j = a, m; for emitting the laser light itself or the mie-scattering signal, j = a, Δ v _a ＝δv/(4ln2) ^1/2 δ v is the laser emission spectral width (FWHM); for rayleigh scatter signals j = m, Δ v _m ＝[(δv) ² /(4ln2)+8kT/Mλ ² ] ^1/2 Wherein T is the atmospheric temperature; λ is the laser wavelength; k is Boltzmann constant; m atmospheric molecular mass; v. of _s The center frequency of the backscatter spectrum.

The center frequency is v _s Atmospheric meter and Rayleigh backscattered light of Gaussian spectral distribution in 2 theta ₀ The total divergence angle incident transmittance of the single-pass F-P interferometer and the double-pass F-P interferometer is respectively as follows:

wherein:

thus, when the laser is vertically emitted, the number of the atmospheric backscattered light photons at the height z received by the signal detector and the energy monitoring detector of the double-pass F-P interferometer 1, the double-pass F-P interferometer 2 and the F-P interferometer M is equal to

N ₁ (z，v ₀ ，T)＝a ₁ [N _a (z)G _1a (v ₀ )+N _m (z)G _1m (v ₀ ，T)]

N ₂ (z，v ₀ ，T)＝a ₂ [N _a (z)G _2a (v ₀ )+N _m (z)G _2m (v ₀ ，T)]

N _M (z，v ₀ ，T)＝a _M [N _a (z)g _Ma (v ₀ )+N _m (z)g _Mm (v ₀ ，T)]

N _E (z，v ₀ ，T)＝a _E [N _a (z)+N _m (z)]

In the formula: a is a ₁ ，a ₂ ，a _M ，a _E Calibrating a constant for the system; t is the atmospheric temperature at z height; n is a radical of _m (z) and N _a (z) is the number of electrons of the meter and Rayleigh backward scattered light between the vertical height z to z + Delta z received by the laser radar receiver, and Delta z is the vertical distance resolution. G in the above two formulae (1) to (2) _1a (v ₀ ) And G _2a (v ₀ ) The signal is very small, and the meter scattering signal item can be ignored; (3) In the formulae (1) to (4) _Ma (v ₀ ) And g _Mm (v ₀ ) Can be obtained by calibrating the system transmittance curve, and then obtaining N according to the two formulas _a (z) the correction signal of the energy monitoring channel is

Defining a temperature response function Q _T Comprises the following steps:

according to Q _T The functional relationship with T can be inverted to obtain the atmospheric temperature. When the laser is emitted along other radial inclined paths, the number of atmospheric backscattered photons at the height z received by the signal detectors of the two-way F-P interferometer 1 and the two-way F-P interferometer 2 is equal to

N ₁ (z，v，T)＝a ₁ [N _a (z)G _1a (v)+N _m (z)G _1m (v，T)]

N ₂ (z，v，T)＝a ₂ [N _a (z)G _2a (v)+N _m (z)G _2m (v，T)]

Defining a wind speed response function Q _V Comprises the following steps:

the emitted laser frequency v measured by the F-P interferometer L ₀ And the atmospheric temperature T profile obtained in the vertical measurement is substituted into the formula, and the radial wind speed can be obtained through inversion.

The structure of the present invention is shown in fig. 2. 355nm seed injection pulse laser is used as an emission source to emit 355nm narrow-linewidth pulse light. The emitted laser is divided into two beams by the first beam splitter, transmitted light occupying most energy is expanded by the beam expander, guided by the first 45-degree reflector and the two-dimensional scanner, and finally vertically penetrates through the glass flat plate at a preset angle to enter an atmosphere measured area. Atmospheric back scattered light is received by the Cassegrain telescope, is coupled into an optical fiber jumper, is collimated by the first collimating lens and filtered by the narrow-band interference filter, and is divided into two beams by the second beam splitter. The transmitted light beams are converged to a photosensitive surface of a first photomultiplier by a first convex lens; the reflected beam is split into two beams by the third beam splitter. A beam of light which is normally incident to a channel M of the four-channel double-pass F-P interferometer is the F-P interferometer, and transmitted beams of the light are converged to a photosensitive surface of a second photomultiplier by a second convex lens; the other beam is split into two beams by the fourth beam splitter. After a transmitted light beam is reflected twice by a first secondary reflection right-angle prism, the transmitted light beam is reversely and normally incident to the F-P interferometer 1 through a first optical isolator, and the light beam which passes through the F-P interferometer 1 again is converged to a photosensitive surface of a third photomultiplier through a third convex lens; and the other beam is reflected by a second 45-degree reflector, is normally incident to a channel 2 of the four-channel double-pass F-P interferometer, namely the F-P interferometer 2, is reflected twice by a second secondary reflection right-angle prism, is reversely and normally incident to the F-P interferometer 2 through a second optical isolator, and is converged to a photosensitive surface of a fourth photomultiplier through a fourth convex lens. The first beam splitter reflecting light with little energy as reference light for measuring and locking the frequency of the emitted laser light is coupled into one of the branch ends of the first 1 x 2 fiber coupler by the fifth convex lens. After passing through a section of 100m long multimode bare fiber, the backward scattered light is output from the other branch end of the first 1X 2 fiber coupler, enters the beam combining end of the second 1X 2 fiber coupler and is output from one branch end. The output light of the branch end is collimated by the second collimating mirror and then divided into two beams by the fifth beam splitter. The transmitted light beams are converged to a photosensitive surface of a fifth photomultiplier by a sixth convex lens; the reflected light beam is normally incident to a channel L of the four-channel double-pass F-P interferometer, namely the F-P interferometer L, and the light beam penetrating through the F-P interferometer L is converged to the photosensitive surface of the sixth photomultiplier by the seventh convex lens. The four-channel double-pass F-P interferometer adopts an integrated design to ensure the relative stability among frequency spectrums, the four channels respectively correspond to the F-P interferometer 1, the F-P interferometer 2, the F-P interferometer M and the F-P interferometer L, and the free spectrum spacing is 12GHz. The spectral widths of the F-P interferometer 1 and the F-P interferometer 2 are both 2.2GHz, the spectral peak-to-peak intervals of the two are 5.8GHz, the effective light-passing apertures are divided into two parts, and the two parts and the two secondary reflection right-angle prisms form a reciprocating double-pass light path respectively, so that incident light beams repeatedly penetrate through the F-P interferometer 1 and the F-P interferometer 2 twice. The spectral widths of the F-P interferometer M and the F-P interferometer L are both 1GHz, the intervals between the spectral peaks of the F-P interferometer M and the F-P interferometer L are 2.9GHz and 2.4GHz, and the F-P interferometer L are both designed into single-pass optical paths and are respectively used for measuring aerosol and measuring and locking the frequency of emitted laser. The emitted laser frequency is locked at the right half waist of the F-P interferometer L, i.e. the position of the spectral peak of the F-P interferometer M or the position of the intersection of the frequency spectra of the F-P interferometer 1 and the F-P interferometer 2. The design parameters of the four-channel double-pass F-P interferometer give consideration to the measurement of high and low layer wind fields and temperature. When the transmittance is calibrated and measured, the other branch end of the second 1X 2 optical fiber coupler is connected to the incident port of the first collimating mirror in place of the optical fiber jumper, and the incident port adopts an SMA interface, so that the insertion and the extraction are convenient. The first photomultiplier, the second photomultiplier, the third photomultiplier and the fourth photomultiplier adopt a large dynamic range photomultiplier module, are in two working modes of simulation and photon counting at the same time, and output signals of the modules are collected by a Licel transient recorder; the fifth photomultiplier and the sixth photomultiplier are always in a simulation working mode, output signals of the fifth photomultiplier and the sixth photomultiplier are collected by an analog/digital (A/D) device, and finally, an industrial personal computer is used for data processing, storage, data inversion, result display and the like. 355nm seed injection pulse laser, four-channel double-pass F-P interferometer, two-dimensional scanner, licel transient recorder, A/D and the like of the whole system are controlled by an industrial control unit through RS232 interfaces.

The laser radar system consists of a 355nm seed injection pulse laser, a first beam splitter, a beam expander, a first 45-degree reflector, a two-dimensional scanner, a glass flat plate, a Saggerin telescope, an optical fiber jumper, a first collimator, a narrow-band interference filter, a second beam splitter, a first convex lens, a first photomultiplier, a third beam splitter, a four-channel two-way F-P interferometer, a second convex lens, a second photomultiplier, a fourth beam splitter, a first secondary reflection right-angle prism, a first optical isolator, a third convex lens, a third photomultiplier, a second 45-degree reflector, a second secondary reflection right-angle prism, a second optical isolator, a fourth convex lens, a fourth photomultiplier, a fifth convex lens, a first 1 x 2 optical fiber coupler, a 100 m-length multimode bare optical fiber, a second 1 x 2 optical fiber coupler, a second collimator, a fifth beam splitter, a sixth convex lens, a fifth photomultiplier, a seventh optical fiber coupler, a sixth electric fiber coupler, a power supply, a transient state electric interference controller, a LICE, a-electric control instrument, a power supply, a LID-P-trigger scanner and an industrial personal computer, the method is characterized in that: the 355nm seed injection pulse laser is respectively connected with a laser driving power supply, a controller and a trigger circuit. The laser emitted by the laser is divided into two beams by the first beam splitter, and the transmitted beam occupying most energy is expanded by the beam splitter, guided by the first 45-degree reflector and the two-dimensional scanner and finally vertically penetrates through the glass flat plate at a preset angle to enter an atmosphere measured area. The atmospheric back scattered light is received by the Cassegrain telescope and then coupled into the optical fiber jumper. The receiving end face of the optical fiber jumper is located at the focal point of the Cassegrain, and the emitting end face of the optical fiber jumper is located at the object space focal point of the first collimating mirror. Emergent light of the optical fiber jumper is collimated by the first collimating lens and filtered by the narrow-band interference filter, and then is divided into two beams by the second beam splitter. The transmitted light beam is converged to a photosurface of a first photomultiplier by a first convex lens; the reflected beam is divided into two beams by the third beam splitter. The reflected light beam of the third beam splitter normally enters a channel M of the four-channel double-pass F-P interferometer, namely the F-P interferometer M, and the transmitted light beam is converged to the photosensitive surface of the second photomultiplier by the second convex lens. The transmitted light beam of the third beam splitter is split into two beams by the fourth beam splitter, the reflected light beam normally enters a channel 1 of the four-channel double-pass F-P interferometer, namely the F-P interferometer 1, the transmitted light beam is reflected twice by the first secondary reflection right-angle prism, reversely and normally enters the F-P interferometer 1 through the first optical isolator, and the light beam which passes through the F-P interferometer 1 again is converged to a photosurface of a third photomultiplier through the third convex lens. And after being reflected by the second 45-degree reflecting mirror, the transmitted light beam of the fourth beam splitter is normally incident to a channel 2 of the four-channel double-pass F-P interferometer, namely the F-P interferometer 2, and after being reflected twice by the second secondary reflection right-angle prism, the transmitted light beam of the fourth beam splitter reversely and normally enters the F-P interferometer 2 through the second optical isolator, and the light beam which passes through the F-P interferometer 2 again is converged to a photosensitive surface of a fourth photomultiplier through a fourth convex lens. The reflected beam of the first beam splitter, which is used as reference light for measuring and locking the frequency of the transmitted laser light, is coupled into one of the branch ends of the first 1 × 2 fiber coupler by the fifth convex lens. The beam combining end of the first 1X 2 optical fiber coupler is communicated with a section of 100m long multimode bare optical fiber. After passing through a section of 100m long multimode bare fiber, the reference light is output by the other branch end of the first 1 × 2 fiber coupler, and the branch end is communicated with the beam combining end of the second 1 × 2 fiber coupler. The light entering the beam combining end of the second 1 x 2 optical fiber coupler is output from one branch end of the second 1 x 2 optical fiber coupler, and the optical fiber end face of the branch end is positioned at the object focus of the second collimating mirror. The output light of the branch end is collimated by the second collimating mirror and then divided into two beams by the fifth beam splitter. The transmitted light beams are converged to a photosensitive surface of a fifth photomultiplier by a sixth convex lens; the reflected light beam normally enters a channel L of the four-channel double-pass F-P interferometer, namely the F-P interferometer L, and the light beam penetrating through the F-P interferometer L is converged to the photosensitive surface of the sixth photomultiplier by the seventh convex lens. The four-channel double-pass F-P interferometer is designed into a whole, and the relative stability among the frequency spectrums is ensured. The four channels are respectively called as a channel 1, a channel 2, a channel M and a channel L and correspond to the F-P interferometer 1, the F-P interferometer 2, the F-P interferometer M and the F-P interferometer L, and the free spectrum spacing is 12GHz. The spectral widths of the F-P interferometer 1 and the F-P interferometer 2 are both 2.2GHz, and the interval between the spectral peaks of the two is 5.8GHz; the spectral widths of the F-P interferometer M and the F-P interferometer L are both 1GHz, and the intervals between the spectral peaks of the F-P interferometer M and the F-P interferometer L are respectively 2.9GHz and 2.4GHz. The design parameters of the four-channel double-pass F-P interferometer give consideration to the measurement of high and low-layer wind fields and temperature. The emitted laser frequency is locked at the right half waist of the F-P interferometer L, i.e. the position of the spectral peak of the F-P interferometer M or the position of the intersection of the two-way F-P interferometer 1 and F-P interferometer 2 spectra. When the transmittance calibration measurement is carried out, the other branch end of the second 1X 2 optical fiber coupler is connected into the entrance port of the first collimating mirror in a manner of replacing an optical fiber jumper, and the entrance port adopts an SMA interface so as to be convenient for plugging and unplugging. The first photomultiplier, the second photomultiplier, the third photomultiplier and the fourth photomultiplier are connected with a Licel transient recorder; the fifth photomultiplier and the sixth photomultiplier are connected to the A/D. The first photomultiplier, the second photomultiplier, the third photomultiplier and the fourth photomultiplier adopt a large dynamic range photomultiplier module, are in two working modes of simulation and photon counting, and output signals of the photomultiplier are collected by a Licel transient recorder. The fifth photomultiplier and the sixth photomultiplier are always in a simulation working mode, and output signals of the fifth photomultiplier and the sixth photomultiplier are collected by an A/D. The Licel transient recorder and the A/D are connected with the trigger circuit, the F-P interferometer controller is connected with the four-channel double-pass F-P interferometer, and the two-dimensional scanner controller is connected with the two-dimensional scanner. The trigger circuit, the F-P interferometer controller, the two-dimensional scanner controller, the laser driving power supply and the controller are connected with an industrial personal computer and are controlled by the industrial personal computer in a unified way.

Due to the adoption of the technical scheme, the invention has the advantages and positive effects that: compared with the traditional Rayleigh Doppler double-edge technology, the method has the advantages that 1, the wind speed and temperature measurement sensitivity can be obviously improved, the interference of rice scattering signals can be strongly inhibited, the wind speed and temperature measurement precision is further improved, and particularly, the wind field and temperature measurement precision near low-layer and medium-layer cloud layers or volcanic ash is improved; 2. the optimally designed system parameters give consideration to high and low layer wind fields and temperature measurement, and the high and low layer atmospheric wind fields and temperature can be simultaneously detected with high precision by a single laser radar.

Drawings

FIG. 1 is a schematic diagram of the wind speed and temperature measurement of the present invention.

Fig. 2 is a block diagram of the architecture of the present invention.

In the figure, 1.355nm seed injection pulse laser, 2. A first beam splitter, 3. A beam expander, 4. A first 45-degree reflector, 5. A two-dimensional scanner, 6. A glass flat plate, 7. A Cassegrain telescope, 8. An optical fiber jumper, 9. A first collimating mirror, 10. A narrow-band interference filter, 11. A second beam splitter, 12. A first convex lens, 13. A first photomultiplier, 14. A third beam splitter, 15. A four-channel double-pass F-P interferometer, 16. A second convex lens, 17. A second photomultiplier, 18. A fourth beam splitter, 19. A first secondary reflection right-angle prism, 20. A first optical isolator, 21. A third convex lens, 22. A third photomultiplier, 23, a second 45-degree reflector, 24, a second secondary reflection right-angle prism, 25, a second optical isolator, 26, a fourth convex lens, 27, a fourth photomultiplier, 28, a fifth convex lens, 29, a first 1X 2 optical fiber coupler, a 30.100m long multimode bare fiber, 31, a second 1X 2 optical fiber coupler, 32, a second collimator, 33, a fifth beam splitter, 34, a sixth convex lens, 35, a fifth photomultiplier, 36, a seventh convex lens, 37, a sixth photomultiplier, 38.Licel transient recorder and A/D,39, a trigger circuit, a 40.F-P interferometer controller, 41, a two-dimensional scanner controller, 42, a laser driving power supply and controller, 43, and an industrial personal computer.

Detailed Description

The structure block of the invention is shown in figure 2. In fig. 2, a 355nm seed injection pulse laser (1) is respectively connected with a laser driving power supply, a controller (38) and a trigger circuit (35). Laser emitted by the 355nm seed injection pulse fiber laser (1) is divided into two beams by a first beam splitter (2). The transmitted light beams occupying most energy are expanded by the beam expander (3), guided by the first 45-degree reflector (4) and the two-dimensional scanner (5), and finally vertically penetrate through the glass flat plate (6) at a preset angle to enter an atmosphere measured area. Atmospheric back-scattered light is received by a Cassegrain telescope (7) and then is coupled into an optical fiber jumper (8). The receiving end face of the optical fiber jumper (8) is located at the focal point of the Cassegrain, and the emergent end face of the optical fiber jumper is located at the focal point of the object space of the first collimating mirror (9). Emergent light of the optical fiber jumper (8) is collimated by the first collimating lens (9) and filtered by the narrow-band interference filter (10), and then is divided into two beams by the second beam splitter (11). The transmitted light beams are converged to a photosensitive surface of a first photomultiplier (13) by a first convex lens (12); the reflected beam is split into two beams by a third beam splitter (14). The reflected light beam of the third beam splitter (14) is normally incident to a channel M of a four-channel double-pass F-P interferometer (15), namely the F-P interferometer M, and the transmitted light beam is converged to the photosensitive surface of a second photomultiplier (17) by a second convex lens (16). The transmitted light beam of the third beam splitter (14) is split into two beams by a fourth beam splitter (18), the reflected light beam normally enters a channel 1 of a four-channel double-pass F-P interferometer (15), namely the F-P interferometer (1), after being reflected twice by a first secondary reflection right-angle prism (19), the transmitted light beam reversely and normally enters the F-P interferometer (1) through a first optical isolator (20), and the light beam which passes through the F-P interferometer (1) again is converged to a photosurface of a third photomultiplier (22) through a third convex lens (21). After being reflected by a second 45-degree reflecting mirror (23), the transmitted light beam of the fourth beam splitter (18) is normally incident to a channel 2 of a four-channel double-pass F-P interferometer (15), namely the F-P interferometer 2, after being reflected twice by a second secondary reflection rectangular prism (24), the transmitted light beam is reversely and normally incident to the F-P interferometer 2 through a second optical isolator (25), and the light beam which is transmitted again through the F-P interferometer 2 is converged to a photosurface of a fourth photomultiplier (27) through a fourth convex lens (26). The reflected beam of the first beam splitter (2) is used as reference light for measuring and locking the emitted laser frequency, which is coupled into one branch end of the first 1 x 2 fiber coupler (29) by the fifth convex lens (28). The beam combining end of the first 1 x 2 optical fiber coupler (29) is communicated with a section of 100m long multimode bare fiber (30). After passing through a section of 100m long multimode bare fiber (30), the reference light is output by the other branch end of the first 1X 2 fiber coupler (29) after being broadened to quasi-continuous light in the time domain, and the branch end is communicated with the beam combining end of the second 1X 2 fiber coupler (31). The light entering the beam combining end of the second 1 x 2 optical fiber coupler (31) is output from one branch end, and the optical fiber end surface of the branch end is positioned at the object focus of the second collimating mirror (32). The output light of the branch end is collimated by a second collimating mirror (32) and then divided into two beams by a fifth beam splitter (33). The transmitted light beams are converged to a photosensitive surface of a fifth photomultiplier (35) by a sixth convex lens (34); the reflected light beam normally enters a channel L of the four-channel double-pass F-P interferometer (15), namely the F-P interferometer L, and the light beam transmitted by the F-P interferometer L is converged to a photosensitive surface of a sixth photomultiplier (37) by a seventh convex lens (36). When the transmittance calibration measurement is carried out, the other branch end of the second 1X 2 optical fiber coupler (31) replaces the optical fiber jumper (8) to be connected into the incident port of the first collimating mirror (9), and the incident port adopts an SMA interface to facilitate plugging and unplugging. A first photomultiplier (13), a second photomultiplier (17), a third photomultiplier (22) and a fourth photomultiplier (27) are connected with a Licel transient recorder and a Licel transient recorder in an A/D (38); the fifth photomultiplier (35) and the sixth photomultiplier (37) are connected to the A/D of the Licel transient recorder and A/D (38). The first photomultiplier (13), the second photomultiplier (17), the third photomultiplier (22) and the fourth photomultiplier (27) adopt a large dynamic range photomultiplier module, are in two working modes of simulation and photon counting at the same time, and output signals of the photomultipliers are collected by a Licel transient recorder. The fifth photomultiplier (35) and the sixth photomultiplier (37) are always in a simulation working mode, and output signals of the fifth photomultiplier and the sixth photomultiplier are collected by an analog/digital (A/D) system. The Licel transient recorder is connected with the A/D (38) and the trigger circuit (39), the F-P interferometer controller (40) is connected with the four-channel double-pass F-P interferometer (15), and the two-dimensional scanner controller (41) is connected with the two-dimensional scanner (5). The trigger circuit (39), the F-P interferometer controller (40), the two-dimensional scanner controller (41), the laser driving power supply and controller (42) are connected with an industrial personal computer (43) and are controlled by the industrial personal computer (43) in a unified mode.

Claims

1. <xnotran> F-P , 355nm , , , 45 , , , , , , , , , , , F-P , , , , , , , , 45 , , , , , , 1 × 2 , 100m , 1 × 2 , , , , , , , licel A/D, , F-P , , , : </xnotran> The 355nm seed injection pulse laser is respectively connected with a laser driving power supply, a controller and a trigger circuit. The laser emitted by the laser is divided into two beams by the first beam splitter, and the transmitted light beam occupying most energy is expanded by the beam splitter, guided by the first 45-degree reflector and the two-dimensional scanner and finally vertically penetrates through the glass flat plate at a preset angle to enter an atmospheric measured area. The atmospheric back scattered light is received by the Cassegrain telescope and then coupled into the optical fiber jumper. The receiving end face of the optical fiber jumper is located at the focal point of the Cassegrain, and the emitting end face of the optical fiber jumper is located at the object space focal point of the first collimating mirror. Emergent light of the optical fiber jumper is collimated by the first collimating lens and filtered by the narrow-band interference filter, and then is divided into two beams by the second beam splitter. The transmitted light beams are converged to a photosensitive surface of a first photomultiplier by a first convex lens; the reflected beam is split into two beams by the third beam splitter. The reflected light beam of the third beam splitter normally enters a channel M of the four-channel double-pass F-P interferometer, namely the F-P interferometer M, and the transmitted light beam is converged to the photosensitive surface of the second photomultiplier by the second convex lens. The transmitted light beam of the third beam splitter is divided into two beams by the fourth beam splitter, the reflected light beam normally enters a channel 1 of the four-channel double-pass F-P interferometer, namely the F-P interferometer 1, after being reflected twice by the first secondary reflection right-angle prism, the transmitted light beam reversely and normally enters the F-P interferometer 1 through the first optical isolator, and the light beam which again passes through the F-P interferometer 1 is converged to the photosurface of the third photomultiplier through the third convex lens. And after being reflected by the second 45-degree reflecting mirror, the transmitted light beam of the fourth beam splitter is normally incident to a channel 2 of the four-channel double-pass F-P interferometer, namely the F-P interferometer 2, and after being reflected twice by the second secondary reflection right-angle prism, the transmitted light beam of the fourth beam splitter reversely and normally enters the F-P interferometer 2 through the second optical isolator, and the light beam which passes through the F-P interferometer 2 again is converged to a photosensitive surface of a fourth photomultiplier through a fourth convex lens. The reflected beam of the first beam splitter, which is used as reference light for measuring and locking the frequency of the emitted laser light, is coupled into one branch end of the first 1 × 2 fiber coupler by the fifth convex lens. The beam combining end of the first 1X 2 optical fiber coupler is communicated with a section of 100m long multimode bare optical fiber. After passing through a section of 100m long multimode bare fiber, the reference light is output by the other branch end of the first 1 × 2 fiber coupler, and the branch end is communicated with the beam combining end of the second 1 × 2 fiber coupler. The light entering the beam combining end of the second 1 x 2 optical fiber coupler is output from one branch end of the second 1 x 2 optical fiber coupler, and the optical fiber end face of the branch end is positioned at the object focus of the second collimating mirror. The output light of the branch end is collimated by the second collimating mirror and then divided into two beams by the fifth beam splitter. The transmitted light beams are converged to a photosensitive surface of a fifth photomultiplier by a sixth convex lens; the reflected light beam is normally incident to a channel L of the four-channel double-pass F-P interferometer, namely the F-P interferometer L, and the light beam penetrating through the F-P interferometer L is converged to the photosensitive surface of the sixth photomultiplier by the seventh convex lens. The four-channel double-pass F-P interferometer is designed into a whole, and the relative stability among the frequency spectrums is ensured. The four channels are respectively called as a channel 1, a channel 2, a channel M and a channel L and correspond to the F-P interferometer 1, the F-P interferometer 2, the F-P interferometer M and the F-P interferometer L, and the free spectrum spacing is 12GHz. The spectral widths of the F-P interferometer 1 and the F-P interferometer 2 are both 2.2GHz, and the interval between the spectral peaks of the two is 5.8GHz; the spectral widths of the F-P interferometer M and the F-P interferometer L are both 1GHz, and the intervals between the spectral peaks of the F-P interferometer M and the F-P interferometer L are respectively 2.9GHz and 2.4GHz. The design parameters of the four-channel double-pass F-P interferometer give consideration to the measurement of high and low layer wind fields and temperature. The emitted laser frequency is locked at the right half waist of the F-P interferometer L, i.e. the position of the spectral peak of the F-P interferometer M or the position of the intersection of the spectra of the two-way F-P interferometer 1 and the F-P interferometer 2. When the transmittance is calibrated and measured, the other branch end of the second 1X 2 optical fiber coupler is connected to the incident port of the first collimating mirror in place of the optical fiber jumper, and the incident port adopts an SMA interface, so that the insertion and the extraction are convenient. The first photomultiplier, the second photomultiplier, the third photomultiplier and the fourth photomultiplier are connected with a Licel transient recorder; the fifth photomultiplier and the sixth photomultiplier are connected to the A/D. The first photomultiplier, the second photomultiplier, the third photomultiplier and the fourth photomultiplier adopt a large dynamic range photomultiplier module, are in two working modes of simulation and photon counting, and output signals of the photomultiplier are collected by a Licel transient recorder. The fifth photomultiplier and the sixth photomultiplier are always in a simulation working mode, and output signals of the fifth photomultiplier and the sixth photomultiplier are collected by an analog/digital (A/D) device. The Licel transient recorder and the A/D are connected with the trigger circuit, the F-P interferometer controller is connected with the four-channel double-pass F-P interferometer, and the two-dimensional scanner controller is connected with the two-dimensional scanner. The trigger circuit, the F-P interferometer controller, the two-dimensional scanner controller, the laser driving power supply and the controller are connected with the industrial personal computer and are controlled by the industrial personal computer in a unified mode.