Raman temperature and humidity profile laser radar optical system

Abstract

The invention provides a Raman temperature and humidity profile laser radar optical system. The Raman temperature and humidity profile laser radar optical system comprises a receiving telescope, a color separation system, a nitrogen Raman / water Raman channel system and a grating light splitting system, backscattering signals of emitted light beams are received through a telescope, are subjected to light splitting after being collimated through an aperture diaphragm to obtain a 355nm nitrogen Raman channel and a 355nm water Raman channel, are converged and then enter a double-grating light splitting optical system to be subjected to light splitting, high-order and low-order rotating Raman scattering signals are separated out and enter a PMT (photomultiplier) detector through light guide of an optical fiber, and the high-order and low-order rotating Raman scattering signals are obtained. And a temperature and humidity profile is obtained after conversion by a photon detection technology. The receiving optical system designed by the invention can realize integrated and miniaturized detection of temperature and humidity profiles, and meets the requirements of applications such as high-precision meso-and-small-scale numerical weather forecast, high-precision calibration of optical and infrared spectrum remote sensing satellite data, atmospheric correction and the like on high-precision troposphere atmospheric temperature and humidity profile data.

Description

Technical Field

[0001] The invention relates to the field of measurement and testing technology, and in particular to a Raman temperature and humidity profile laser radar optical system. Background Art

[0002] At present, the development of advanced science and technology such as aviation and aerospace has raised many new issues and requirements for meteorological work based on temperature and humidity measurement. The development of science and technology has developed from the traditional three-dimensional sea, land and air to the five dimensions of sea, land, air, space and electricity. The spatial center of gravity of technology has moved upward, raising many issues on temperature and humidity detection in the troposphere.

[0003] Modern high-tech technologies use a lot of optoelectronic systems, which raises a lot of issues related to the transmission of electromagnetic waves in the atmosphere, which places high demands on the accuracy of temperature and humidity forecasts. In addition, the accuracy of contemporary high-tech equipment is increasing, and its performance is becoming more and more sensitive to the atmospheric environment. The impact of key environmental parameters such as atmospheric temperature and humidity on its performance or accuracy is becoming an increasingly important factor. Summary of the invention

[0004] The present invention is to solve the problem of temperature and humidity forecast accuracy, and provides a Raman temperature and humidity profile laser radar optical system, which receives the backscattered signal of the transmitted light beam through a telescope, obtains the 355nm nitrogen Raman channel and the water Raman channel after the aperture stop and collimation, and then enters the double grating spectroscopic optical system for spectrometry after convergence, separates the high and low order rotational Raman scattering signals, enters the PMT (photomultiplier tube) detector through the optical fiber, and obtains the temperature and humidity profile after conversion through the photon detection technology. The receiving optical system designed by the present invention can realize the integrated and miniaturized detection of the temperature and humidity profile, and meet the needs of high-precision tropospheric atmospheric temperature and humidity profile data for applications such as high-precision small and medium-scale numerical weather forecasts, high-precision calibration of optical and infrared spectrum remote sensing satellite data, and atmospheric correction.

[0005] The present invention proposes to carry out research on key technologies for joint detection and inversion of active and passive atmospheric temperature and humidity profiles throughout the day, breaking through the limitations of a single technology on high-precision, high temporal and spatial resolution temperature and humidity profile detection, to meet the urgent needs of current atmospheric temperature and humidity detection technology, and lay the foundation for the development of a new generation of joint technology systems.

[0006] The present invention provides a Raman temperature and humidity profile laser radar optical system, comprising an optically connected receiving telescope, a color separation system, and a nitrogen Raman / water Raman channel system and a grating spectrometer system optically connected to the output end of the color separation system respectively;

[0007] The color separation system converges and collimates the echo signals received by the receiving telescope to separate the 386nm echo signal, the 407nm echo signal and the 355nm echo signal, and then converges the separated 355nm echo signal onto the focal plane of the grating spectrometer system through the focusing lens group, and outputs the 386nm echo signal and the 407nm echo signal to the nitrogen Raman / water Raman channel system;

[0008] The nitrogen Raman / water Raman channel system separates the 386nm echo signal and the 407nm echo signal, and then narrow-band filters the 386nm echo signal and converges it into the 355nm nitrogen Raman channel detector, and narrow-band filters the 407nm echo signal and converges it into the 355nm water Raman channel detector;

[0009] The grating spectroscopic system converges the 355nm echo signal and then performs spectroscopic analysis through the first double-grating spectroscopic optical system to separate the elastic scattering signal, the positive Stokes high-order rotation Raman signal, the positive Stokes low-order rotation Raman signal, the anti-Stokes high-order rotation Raman signal, and the anti-Stokes low-order rotation Raman signal. The elastic scattering signal is output to the 355nm elastic scattering through the detector through the optical fiber. The positive Stokes high-order rotation Raman signal, the positive Stokes low-order rotation Raman signal, the anti-Stokes high-order rotation Raman signal, and the anti-Stokes low-order rotation Raman signal are spectroscopically analyzed and separated again, and the positive Stokes high-order rotation Raman signal and the anti-Stokes high-order rotation Raman signal are synthesized to obtain the positive and anti-Stokes high-order rotation Raman signal, the positive Stokes low-order rotation Raman signal and the anti-Stokes low-order rotation Raman signal are synthesized to obtain the positive and anti-Stokes low-order rotation Raman signal, and the positive and anti-Stokes high-order rotation Raman signal and the positive and anti-Stokes low-order rotation Raman signal are respectively guided into the detector through the optical fiber.

[0010] The 386nm echo signal is the nitrogen vibration Raman backscattering signal, and the 407nm echo signal is the water vapor vibration Raman backscattering signal. The nitrogen vibration Raman backscattering signal and the water vapor vibration Raman backscattering signal are used to invert the humidity profile.

[0011] The elastic scattering signal, positive and negative Stokes high-order rotation Raman signal and positive and negative Stokes low-order rotation Raman signal output by the grating spectrometer system are used to invert the temperature profile.

[0012] The Raman temperature and humidity profile laser radar optical system described in the present invention, as a preferred embodiment, the color separation system includes a first focusing lens group, a pinhole aperture, a first collimating lens group, a first color separation mirror, and a second focusing lens group optically connected in sequence; the first focusing lens group is optically connected to the output end of the receiving telescope, the refraction optical path output end of the first color separation mirror is optically connected to the input end of the nitrogen Raman / water Raman channel system, and the output end of the second focusing lens group is optically connected to the input end of the grating spectroscopic system;

[0013] The first focusing mirror group converges the echo signal, the pinhole aperture suppresses background noise, the first collimating mirror group performs collimation and color separation, the first color separation mirror transmits the 355nm echo signal to the second focusing mirror group, reflects the 386nm echo signal and the 407nm echo signal to the color separation mirror of the nitrogen Raman / water Raman channel system, and the second focusing mirror group converges the 355nm echo signal to the focal plane of the grating spectrometer system.

[0014] In the Raman temperature and humidity profile laser radar optical system described in the present invention, as a preferred embodiment, the receiving telescope is an afocal system;

[0015] The aperture of the primary mirror of the receiving telescope is The radius of curvature R is 1200mm, the off-axis distance is 175mm, and the secondary mirror aperture is The radius of curvature is R96mm and the off-axis amount is 14mm. Both the primary and secondary mirrors are made of microcrystalline glass.

[0016] The Raman temperature and humidity profile laser radar optical system described in the present invention, as a preferred embodiment, the nitrogen Raman / water Raman channel system includes a second dichroic mirror, a first filter optically connected to the reflection end of the second dichroic mirror in sequence, a 386-channel focusing lens group, a 355nm nitrogen Raman channel detector, and a second filter optically connected to the transmission end of the second dichroic mirror in sequence, a 407-channel focusing lens group and a 355nm water Raman channel detector;

[0017] The second dichroic mirror reflects the 386nm echo signal output by the color separation system to the first filter for narrow-band filtering, and then the 386-channel focusing lens group converges it into the 355nm nitrogen Raman channel detector;

[0018] The second dichroic mirror reflects the 407nm echo signal output by the color separation system to the second filter for narrow-band filtering, and then the 407-channel focusing lens group converges it into the 355nm water Raman channel detector.

[0019] The Raman temperature and humidity profile laser radar optical system described in the present invention is preferably configured such that the aperture of the color separation system is 10 mm and the diameter of the convergent light spot is 0.6 mm.

[0020] The first focusing lens group and the second focusing lens group each include two lenses optically connected in sequence and a biconcave lens;

[0021] The pinhole diaphragm is located at the focus of the first focusing lens group;

[0022] The first collimator lens group includes three lenses, which are two optically connected plano-convex lenses and a meniscus lens, all of which are made of quartz, with a focal length of 30 mm. The collimated beam diameter is less than 20 mm within 300 mm. The first collimator lens group completes the color separation of 355 nm, 386 nm, and 407 nm in the collimated beam.

[0023] The first dichroic mirror is coated with a dichroic film, transmits light with a wavelength of 355nm, and reflects light with a wavelength of 387nm and light with a wavelength of 407nm;

[0024] The first focusing lens group and the second focusing lens group each include 3 lenses, the focal length of the second focusing lens group is 24.1 mm, and the image size after convergence is 0.58 mm;

[0025] The second dichroic mirror is coated with a dichroic film, transmits 407nm wavelength light, and reflects 387nm wavelength light;

[0026] The first filter and the second filter are both interference filters with a bandwidth of 500 pm. The apertures of the 386-channel focusing lens group and the 407-channel focusing lens group are both 25 mm and the focal lengths are both 25 mm.

[0027] A Raman temperature and humidity profile laser radar optical system described in the present invention, as a preferred embodiment, the grating spectroscopic system includes a first focal plane optically connected to the output end of the second focusing lens group, a second collimating lens group and a first grating optically connected to the first focal plane in sequence, a first optical fiber, a second optical fiber, a third optical fiber, a fourth optical fiber, and a fifth optical fiber optically connected to the output end of the first focal plane, an elastic scattering channel detector connected to the first optical fiber, a second focal plane optically connected to the second optical fiber, the third optical fiber, the fourth optical fiber, and the fifth optical fiber, a third collimating lens group and a second grating optically connected to the second focal plane in sequence, and a first rotation Raman channel detector and a second rotation Raman channel detector optically connected to the second focal plane respectively;

[0028] The first focal plane receives the 355nm echo signal output by the second focusing lens group and diverges it, and after passing through the second collimating lens group, it is collimated into parallel light and incident on the first grating according to the designed blazing angle. After being dispersed by the first grating, the light of different wavelengths is focused to different positions on the first focal plane by the second collimating lens group; the first optical fiber outputs the elastic scattering signal to the elastic scattering channel detector, and the second optical fiber, the third optical fiber, the fourth optical fiber, and the fifth optical fiber respectively introduce the positive Stokes high-order rotation Raman signal, the positive Stokes low-order rotation Raman signal, the anti-Stokes high-order rotation Raman signal, and the anti-Stokes low-order rotation Raman signal into the second focal plane, and undergoes secondary light splitting through the second grating, so that the positive Stokes high-order rotation Raman signal and the anti-Stokes high-order rotation Raman signal are synthesized and output to the first rotation Raman channel detector, and the positive Stokes low-order rotation Raman signal and the anti-Stokes low-order rotation Raman signal are synthesized and output to the second rotation Raman channel detector;

[0029] The elastic scattering signal is a 354.794nm echo signal, and the positive Stokes high-order rotation Raman signal, the positive Stokes low-order rotation Raman signal, the anti-Stokes high-order rotation Raman signal and the anti-Stokes low-order rotation Raman signal are respectively: 355.547nm echo signal, 356.150nm echo signal, 354.244nm echo signal and 353.647nm echo signal.

[0030] In the Raman temperature and humidity profile laser radar optical system described in the present invention, as a preferred embodiment, the second collimator lens group and the third collimator lens group have the same structure;

[0031] The second collimating lens group includes a first meniscus lens, a second meniscus lens, a third meniscus lens and a plano-convex lens optically connected in sequence;

[0032] The distance for the echo signal to be incident from the field of view of the receiving telescope to the first grating and then return from the first grating to the first focal plane is 4mm. The field of view of the second collimator lens group is 1°×1.3°. The spot size irradiated on the first grating is 50mm. The light at the field aperture of the receiving telescope is incident from the focus on the lower side of the optical path of the second collimator lens group, passes through 4 lenses and reaches the first grating. The diffracted light of the first grating is reflected back through the 4 lenses and converges to the focus on the upper side of the optical path of the second collimator lens group.

[0033] The Raman temperature and humidity profile lidar optical system described in the present invention is, as a preferred embodiment, the second collimator group is a telecentric optical path, the focal length is 120 mm, the aperture is 50 mm, and the total length is 160 mm. The 354.794 nm echo signal, the 355.547 nm echo signal, the 356.150 nm echo signal, the 354.244 nm echo signal, and the 353.647 nm echo signal are directly coupled into the 0.6 mm optical fiber at the second focal plane.

[0034] The Raman temperature and humidity profile laser radar optical system described in the present invention is preferably configured such that the second focal plane output end is sequentially connected to the optical fiber, the fourth collimating lens group, the third filter, and the first focusing lens group to converge to the photosensitive surface of the first rotating Raman channel detector, and the second focal plane output end is sequentially connected to the optical fiber, the fifth collimating lens group, the fourth filter, and the second focusing lens group to converge to the photosensitive surface of the second rotating Raman channel detector, and the fourth collimating lens group and the fifth collimating lens group have the same structure and both include an optically connected meniscus lens and a biconvex lens;

[0035] The core diameter of the optical fiber is 0.6 mm, the numerical aperture is 0.22, the F number of the fourth collimating lens group is 2.2, the aperture is 20 mm, and the focal length is 44 mm; the lenses of the fourth collimating lens group and the fifth collimating lens group both include two quartz lenses with a total length of 26 mm.

[0036] The Raman temperature and humidity profile laser radar optical system described in the present invention is preferably configured such that the spot diameters of the receiving telescope, the color separation system, the nitrogen Raman / water Raman channel system and the grating spectrometer system are all better than 52 μm.

[0037] The present invention consists of two parts: a telescope and a relay optical system. The telescope receives the backscattered light of the signal light, and the relay optical system processes and divides the received backscattered light into 355nm, 386nm and 407nm. The 355nm echo light passes through a double grating monochromator to obtain 354.794nm (center wavelength); 355.547nm; 356.150nm; 354.244nm; 353.647nm. Among them, 355.547nm; 356.150nm; 354.244nm; 353.647nm are directly coupled into the optical fiber, and 354.794nm directly outputs the elastic scattering signal.

[0038] The present invention specifically consists of a receiving telescope, a color separation system, a nitrogen Raman and water Raman channel system, and a grating spectroscopic system. The color separation system consists of a focusing lens group 1, a pinhole diaphragm, a collimating lens group 1, a color separation mirror 1, and a focusing lens group 2. The nitrogen Raman and water Raman channel system consists of a color separation mirror 2, a filter 1, a filter 2, a 386nm channel focusing lens group, a 407nm channel focusing lens group, a 355nm nitrogen Raman channel detector, and a 355nm water Raman channel detector. The grating spectroscopic system consists of a focal plane 1, a collimating lens group 2, a grating 1, a focal plane 2, a grating 2, a rotating Raman channel 1 detector, a rotating Raman channel 2 detector, and a 355nm elastic scattering channel detector.

[0039] The beam splitting path first converges and then collimates the echo signal received by the telescope. The function of convergence is to set the pinhole aperture to suppress background noise, and the function of collimation is to separate the 386nm, 407nm and 355nm echo signals through the dichroic mirror 1. Then the separated 355nm echo signal is converged to the focal plane 1 of the grating beam splitting system through the focusing lens group 2.

[0040] The nitrogen Raman and water Raman channel systems reflect the 386nm echo signal and transmit the 407nm echo signal through the dichroic mirror 2. The reflected 386nm echo signal is narrow-band filtered by the filter 1 and then converged into the 355nm nitrogen Raman channel detector by the 386-channel focusing lens group; the transmitted 407nm echo signal is narrow-band filtered by the filter 2 and then converged into the 355nm water Raman channel detector by the 407-channel focusing lens group.

[0041] The function of the grating spectrometer system is to make the echo signal light reach the focal plane 1 through the color separation system for divergence, and then be collimated into parallel light after passing through the collimator group 2, and then be incident on the grating 1 according to the designed blazing angle. After being dispersed by the grating 1, the light of different wavelengths is focused to different positions on the focal plane 1 through the collimator group 2. The output optical fiber is connected to the focal plane 1, one of which directly outputs the elastic scattering signal, and the other four optical fibers respectively introduce the positive and negative Stokes high and low order rotation Raman signals into the focal plane 2, and perform secondary spectrometry in a similar way to the grating 1. Since the incident position on the focal plane 2 has been accurately calculated, the high order signal can be synthesized into one path, and the low order signal can be synthesized into another path, and then exported separately. In this way, the separation of high and low order rotation Raman signals and the suppression of elastic scattering signal light are completed.

[0042] The present invention can realize the integrated detection of atmospheric temperature and humidity profiles and cloud height, obtain atmospheric temperature and humidity and cloud raw data, combine the existing temperature, humidity and cloud height inversion methods, give the temperature and humidity inversion method through analysis and comparison, and study the temperature and humidity profile and cloud height inversion scheme below the cloud base using the rotating Raman temperature and humidity lidar to obtain key information such as cloud base and cloud top height, cloud phase and so on.

[0043] The present invention has the following advantages:

[0044] Currently, the existing lidar technology basically separates temperature detection and humidity detection, which are two detection systems. The receiving optical system designed in the present invention can realize integrated and miniaturized detection of temperature and humidity profiles, and meet the needs of high-precision tropospheric atmospheric temperature and humidity profile data for applications such as high-precision small and medium-scale numerical weather forecasts, high-precision calibration of optical and infrared spectral remote sensing satellite data, and atmospheric correction. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the structure of a Raman temperature and humidity profile laser radar optical system;

[0046] Figure 2 This is a combined optical design diagram of a telescope and color separation system for a Raman temperature and humidity profile lidar optical system;

[0047] Figure 3 This is an optical design diagram of a collimator group in a grating spectrometer system of a Raman temperature and humidity profile laser radar optical system;

[0048] Figure 4 This is an optical design diagram of a filter assembly for a Raman temperature and humidity profile lidar optical system.

[0049] Reference numerals:

[0050] 1. Receiving telescope; 2. Color separation system; 21. First focusing lens group; 22. Pinhole diaphragm; 23. First collimating lens group; 24. First color separation mirror; 25. Second focusing lens group; 3. Nitrogen Raman / water Raman channel system; 31. Second color separation mirror; 32. First filter; 33. 386 channel focusing lens group; 34. 355nm nitrogen Raman channel detector; 35. Second filter; 36. 407 channel focusing lens group; 37. 355nm Water Raman channel detector; 4, grating spectroscopic system; 41, first focal plane; 42, second collimating lens group; 421, first meniscus lens; 422, second meniscus lens; 423, third meniscus lens; 424, plano-convex lens; 43, first grating; 44, elastic scattering channel detector; 45, second focal plane; 46, third collimating lens group; 47, second grating; 48, first rotational Raman channel detector; 49, second rotational Raman channel detector. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0052] Example 1

[0053] like Figure 1 As shown, a Raman temperature and humidity profile laser radar optical system consists of a telescope 1 and a relay optical system. The relay optical system includes a color separation system 2, a nitrogen Raman / water Raman channel system 3 and a grating spectrometer system 4. The telescope 1 receives the backscattered light of the signal light, and the relay optical system processes and divides the received backscattered light into 355nm, 386nm and 407nm. The 355nm echo light passes through a double grating monochromator 4 to obtain 354.794nm (center wavelength); 355.547nm; 356.150nm; 354.244nm; 353.647nm. Among them, 355.547nm; 356.150nm; 354.244nm; 353.647nm are directly coupled into the optical fiber, and 354.794nm directly outputs the elastic scattering signal.

[0054] The backscattered signal of the transmitted light beam is received by telescope 1, and after being split through aperture diaphragm and collimation, the 355nm nitrogen Raman channel and the water Raman channel are obtained. After being converged, the backscattered signal enters the double grating spectroscopic optical system 4 for splitting, and the high and low order rotational Raman scattering signals are separated. The signals enter the PMT (photomultiplier tube) detector through optical fiber and are converted by photon detection technology to obtain the temperature and humidity profile.

[0055] The present invention can detect and obtain temperature and humidity profiles through the 355nm elastic scattering channel, the rotational Raman temperature measurement channel, and the vibration Raman water vapor channel, and can detect temperature and humidity profiles within an altitude range of 3km during the day and 7km at night in a clear and clean atmosphere. The principle diagram of the optical system is shown in the figure below. Figure 1 , 2 As shown. The receiving telescope 1 is an afocal system. The received echo signal is focused by the first focusing lens group 21. A pinhole diaphragm 22 is placed at the focus of the first focusing lens group 21. Then, it is collimated by the first collimating lens group 23. The collimated echo light is separated by the first dichroic mirror 24, where the 386nm and 407nm echo signals are reflected and the 355nm echo signal is transmitted. The reflected 386nm and 407nm echo signals are separated again by the second dichroic mirror 31, where the 386nm echo light is reflected and the 407nm echo light is transmitted. After entering the narrowband filter and the focusing lens group, they are received by the detector. The 355nm echo light transmitted by the first dichroic mirror 24 is focused on the first focal plane 41 through the second focusing lens group 25, and is collimated into parallel light after passing through the second collimating lens group 42, and is incident on the first grating 43 according to the designed blaze angle. After being dispersed by the first grating 43, the light of different wavelengths is focused on different positions on the first focal plane 41 through the second collimating lens group 42. The output optical fiber is connected to the first focal plane 41, one of which directly outputs the elastic scattering signal, and the other four optical fibers respectively guide the positive and negative Stokes high and low order rotation Raman signals into the second focal plane 45, and secondary light splitting is performed in a similar manner to the first grating 43. Since the incident position on the second focal plane 45 has been accurately calculated, the high order signal can be synthesized into one path, and the low order signal can be synthesized into another path, and then exported separately.

[0056] The following is a detailed description of the above design process:

[0057] (1) Telescope 1 and color separation system 2

[0058] The input parameters for color separation system 2 design are as follows:

[0059] Diameter: 10mm;

[0060] Color separation channels: 355nm, 386nm, 407nm;

[0061] Converging spot diameter: 0.6mm.

[0062] Telescope 1 primary mirror aperture Curvature radius R1200mm, off-axis distance 175mm; secondary mirror aperture The radius of curvature is R96mm, the off-axis distance is 14mm, and both the primary and secondary mirrors are made of microcrystalline glass.

[0063] The collimation part 23 uses three lenses in the optical path, made of quartz with a focal length of 30mm. The diameter of the collimated beam is less than 20mm within 300mm. The color separation of 355nm, 386nm and 407nm is completed in the collimated beam. After color separation, 386nm and 407nm enter the Raman detection channels of the two, and 355nm is focused and enters the grating monochromator 4.

[0064] The converging part of the optical path 25 uses three lenses to achieve light convergence. The focal length of the lens group is 24.1 mm. The size of the image plane after convergence is 0.58 mm. The convergence point spot is small and the energy concentration is high.

[0065] (2) Optical design of grating beam splitting system and 4 collimating lens groups

[0066] like Figure 3 As shown in the figure, the five wavelength channels are obtained by grating splitting. The distance from the field of view of telescope 1 to the grating 43 and the grating 43 to the focal plane of collimator 42 is designed to be 4mm, so the field of view of collimator 42 is 1°×1.3°. The spot size irradiated on grating 43 is 50mm. The optical design is composed of 4 lenses, as shown in the attached figure. Figure 3 As shown, the grating is installed on the left side. The light at the field aperture of the telescope 1 is incident from the focus on the lower side of the collimator 42 optical path, passes through 4 lenses to reach the grating, and the diffracted light of the grating 43 is reflected back by the 4 lenses and converges to the focus on the upper side of the collimator 42 optical path. The collimator group 42 is a telecentric optical path with a focal length of 120mm, an aperture of 50mm, and a total length of 160mm. The spot diameter at each field of view is better than 52um, and the energy concentration is good. 354.794nm, 355.547nm, 356.150nm, 354.244nm, and 353.647nm are directly coupled with 0.6mm optical fiber at the focal plane of the collimator.

[0067] (3) Optical design of filter assembly

[0068] like Figure 4 As shown, the echo signal coupled into the optical fiber through the primary grating 43 is converged to the photosensitive surface of the detector 44 through the collimating lens group-filter-focusing lens group. The echo signal coupled into the optical fiber through the secondary grating 47 is also converged to the photosensitive surfaces of the detectors 48 and 49 through the collimating lens group and the focusing lens group, and the filter is no longer used for filtering. Since the photosensitive surface of the PMT detector is 8x8mm, the focusing lens group is only used to converge and even the light.

[0069] The core diameter of the optical fiber is 0.6mm, the numerical aperture is 0.22, the F number of the collimator is designed to be 2.2, the aperture is designed to be 20mm, and the focal length is 44mm. Two quartz lenses are used, with a total length of 26mm. Add a filter after the collimator according to needs, and connect the lens of the corresponding PMT detection channel.

[0070] (4) 386nm and 407nm Raman channel design

[0071] The 386nm and 407nm Raman echo signals are separated by the splitting optical path and enter the dichroic mirror 31 to separate the 386nm and 407nm echo signals, and then pass through the interference filters 32 and 35 with a bandwidth of 500pm respectively, and are respectively converged to the photosensitive surfaces of detectors 34 and 37 by focusing mirrors 33 and 36. The focusing mirror has an aperture of 25mm and a focal length of 25mm.

[0072] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A Raman temperature and humidity profile laser radar optical system, characterized in that: It comprises an optically connected receiving telescope (1), a color separation system (2), a nitrogen Raman / water Raman channel system (3) and a grating spectroscopic system (4) respectively optically connected to the output ends of the color separation system (2); The color separation system (2) converges and collimates the echo signals received by the receiving telescope (1) to separate the 386nm echo signal, the 407nm echo signal and the 355nm echo signal, and then converges the separated 355nm echo signal onto the focal plane of the grating spectrometer system (4) through a focusing lens group, and outputs the 386nm echo signal and the 407nm echo signal to the nitrogen Raman / water Raman channel system (3); The nitrogen Raman / water Raman channel system (3) separates the 386nm echo signal and the 407nm echo signal, and then narrow-band filters the 386nm echo signal and converges it into a 355nm nitrogen Raman channel detector, and narrow-band filters the 407nm echo signal and converges it into a 355nm water Raman channel detector; The grating spectroscopic system (4) converges the 355nm echo signal and then performs spectroscopic separation through a first double-grating spectroscopic optical system to separate elastic scattering signals, positive Stokes high-order rotation Raman signals, positive Stokes low-order rotation Raman signals, anti-Stokes high-order rotation Raman signals, and anti-Stokes low-order rotation Raman signals. The elastic scattering signal is output to a 355nm elastic scattering detector through an optical fiber, and the positive Stokes high-order rotation Raman signals, the positive Stokes low-order rotation Raman signals, and the anti-Stokes high-order rotation Raman signals are output to a 355nm elastic scattering detector through an optical fiber. The Raman signal and the anti-Stokes low-order rotation Raman signal are split and separated again, and the positive Stokes high-order rotation Raman signal and the anti-Stokes high-order rotation Raman signal are synthesized to obtain a positive and anti-Stokes high-order rotation Raman signal, and the positive Stokes low-order rotation Raman signal and the anti-Stokes low-order rotation Raman signal are synthesized to obtain a positive and anti-Stokes low-order rotation Raman signal, and the positive and anti-Stokes high-order rotation Raman signal and the positive and anti-Stokes low-order rotation Raman signal are respectively guided into the detector through optical fibers; The 386nm echo signal is a nitrogen vibration Raman backscattering signal, and the 407nm echo signal is a water vapor vibration Raman backscattering signal. The nitrogen vibration Raman backscattering signal and the water vapor vibration Raman backscattering signal are used to invert the humidity profile. The elastic scattering signal, the positive and negative Stokes high-order rotation Raman signal and the positive and negative Stokes low-order rotation Raman signal output by the grating spectroscopic system (4) are used to invert the temperature profile.

2. The Raman temperature and humidity profile laser radar optical system according to claim 1, characterized in that: The color separation system (2) comprises a first focusing lens group (21), a pinhole diaphragm (22), a first collimating lens group (23), a first color separation mirror (24), and a second focusing lens group (25) which are optically connected in sequence; the first focusing lens group (21) is optically connected to the output end of the receiving telescope (1), the refraction optical path output end of the first color separation mirror (24) is optically connected to the input end of the nitrogen Raman / water Raman channel system (3), and the output end of the second focusing lens group (25) is optically connected to the input end of the grating light separation system (4); The first focusing lens group (21) converges the echo signal, the pinhole diaphragm (22) suppresses background noise, the first collimating lens group (23) performs collimation and color separation, the first color separation mirror (24) transmits the 355nm echo signal to the second focusing lens group (25), reflects the 386nm echo signal and the 407nm echo signal to the color separation mirror of the nitrogen Raman / water Raman channel system (3), and the second focusing lens group (25) converges the 355nm echo signal to the focal plane of the grating spectroscopic system (4).

3. The Raman temperature and humidity profile laser radar optical system according to claim 2, characterized in that: The receiving telescope (1) is an afocal system; The aperture of the primary mirror of the receiving telescope (1) is The radius of curvature R is 1200mm, the off-axis distance is 175mm, and the secondary mirror aperture is The radius of curvature is R96mm, the off-axis amount is 14mm, and the materials of the primary mirror and the secondary mirror are both microcrystalline glass; The aperture of the color separation system (2) is 10 mm, and the diameter of the convergent light spot is 0.6 mm; The first focusing lens group (21) and the second focusing lens group (25) each comprise two lenses optically connected in sequence and a biconcave lens; The pinhole diaphragm (22) is located at the focal point of the first focusing lens group (21); The first collimator lens group (23) comprises three lenses, which are two optically connected plano-convex lenses and a meniscus lens, all of which are made of quartz, have a focal length of 30 mm, and the collimated light beam aperture is less than 20 mm within 300 mm. The first collimator lens group (23) performs color separation of 355 nm, 386 nm, and 407 nm in the collimated light beam; The first dichroic mirror (24) is coated with a dichroic film, transmits light with a wavelength of 355 nm, and reflects light with a wavelength of 387 nm and light with a wavelength of 407 nm; The first focusing lens group (21) and the second focusing lens group (25) both comprise three lenses; the focal length of the second focusing lens group (25) is 24.1 mm, and the size of the image plane after convergence is 0.58 mm.

4. The Raman temperature and humidity profile laser radar optical system according to claim 1, characterized in that: The nitrogen Raman / water Raman channel system (3) comprises a second dichroic mirror (31), a first filter (32) optically connected in sequence to the reflection end of the second dichroic mirror (31), a 386-channel focusing lens group (33), and a 355nm nitrogen Raman channel detector (34), and a second filter (35) optically connected in sequence to the transmission end of the second dichroic mirror (31), a 407-channel focusing lens group (36), and a 355nm water Raman channel detector (37); The second dichroic mirror (31) reflects the 386nm echo signal output by the color separation system (2) to the first filter (32) for narrow-band filtering, and then the 386-channel focusing lens group (33) converges the signal to the 355nm nitrogen Raman channel detector (34); The second dichroic mirror (31) reflects the 407nm echo signal output by the color separation system (2) to the second filter (35) for narrow-band filtering, and then the 407-channel focusing lens group (36) converges the signal to the 355nm water Raman channel detector (37).

5. The Raman temperature and humidity profile laser radar optical system according to claim 4, characterized in that: The second dichroic mirror (31) is coated with a dichroic film, transmits light with a wavelength of 407 nm, and reflects light with a wavelength of 387 nm; the first filter (32) and the second filter (35) are both interference filters with a bandwidth of 500 pm; the 386-channel focusing lens group (33) and the 407-channel focusing lens group (36) both have an aperture of 25 mm and a focal length of 25 mm.

6. The Raman temperature and humidity profile laser radar optical system according to claim 2, characterized in that: The grating spectroscopic system (4) comprises a first focal plane (41) optically connected to the output end of the second focusing lens group (25), a second collimating lens group (42) and a first grating (43) optically connected to the first focal plane (41) in sequence, a first optical fiber, a second optical fiber, a third optical fiber, a fourth optical fiber and a fifth optical fiber optically connected to the output end of the first focal plane (41), an elastic scattering channel detector (44) connected to the first optical fiber, a second focal plane (45) optically connected to the second optical fiber, the third optical fiber, the fourth optical fiber and the fifth optical fiber, a third collimating lens group (46) and a second grating (47) optically connected to the second focal plane (45) in sequence, and a first rotational Raman channel detector (48) and a second rotational Raman channel detector (49) optically connected to the second focal plane (45) respectively; The first focal plane (41) receives the 355 nm echo signal output by the second focusing lens group (25) and diverges it, and after passing through the second collimating lens group (42), it is collimated into parallel light and incident on the first grating (43) according to the designed blazing angle. After being dispersed by the first grating (43), the light of different wavelengths is focused to different positions on the first focal plane (41) by the second collimating lens group (42); the first optical fiber outputs an elastic scattering signal to the elastic scattering channel detector (44), and the second optical fiber, the third optical fiber, the fourth optical fiber, and the fifth optical fiber respectively transmit the elastic scattering signal to the elastic scattering channel detector (44). The positive Stokes high-order rotational Raman signal, the positive Stokes low-order rotational Raman signal, the anti-Stokes high-order rotational Raman signal and the anti-Stokes low-order rotational Raman signal are introduced into the second focal plane (45), and are subjected to secondary light splitting through the second grating (47), so that the positive Stokes high-order rotational Raman signal and the anti-Stokes high-order rotational Raman signal are synthesized and output to the first rotational Raman channel detector (48), and the positive Stokes low-order rotational Raman signal and the anti-Stokes low-order rotational Raman signal are synthesized and output to the second rotational Raman channel detector (49); The elastic scattering signal is a 354.794nm echo signal, and the positive Stokes high-order rotation Raman signal, the positive Stokes low-order rotation Raman signal, the anti-Stokes high-order rotation Raman signal and the anti-Stokes low-order rotation Raman signal are respectively: a 355.547nm echo signal, a 356.150nm echo signal, a 354.244nm echo signal and a 353.647nm echo signal.

7. The Raman temperature and humidity profile laser radar optical system according to claim 6, characterized in that: The second collimating lens group (42) and the third collimating lens group (46) have the same structure; The second collimating lens group (42) comprises a first meniscus lens (421), a second meniscus lens (422), a third meniscus lens (423) and a plano-convex lens (424) optically connected in sequence; The distance from the field of view of the receiving telescope (1) to the first grating (43) and then back from the first grating (43) to the first focal plane (41) is 4 mm, the field of view of the second collimator lens group (42) is 1°×1.3°, the spot size irradiated on the first grating (43) is 50 mm, the light at the field diaphragm of the receiving telescope (1) is incident from the focus on the lower side of the optical path of the second collimator lens group (42), passes through four lenses and reaches the first grating (43), and the diffracted light of the first grating (43) is reflected back through the four lenses and converges to the focus located on the upper side of the optical path of the second collimator lens group (42).

8. The Raman temperature and humidity profile laser radar optical system according to claim 7, characterized in that: The second collimator lens group (42) is a telecentric optical path, has a focal length of 120 mm, an aperture of 50 mm, and a total length of 160 mm. The 354.794 nm echo signal, the 355.547 nm echo signal, the 356.150 nm echo signal, the 354.244 nm echo signal, and the 353.647 nm echo signal are directly coupled into the 0.6 mm optical fiber at the second focal plane (45).

9. The Raman temperature and humidity profile laser radar optical system according to claim 1, characterized in that: The output end of the second focal plane (45) is sequentially connected to an optical fiber, a fourth collimating lens group, a third filter, and a first focusing lens group to converge to a photosensitive surface of the first rotational Raman channel detector (48); the output end of the second focal plane (45) is sequentially connected to an optical fiber, a fifth collimating lens group, a fourth filter, and a second focusing lens group to converge to a photosensitive surface of the second rotational Raman channel detector (49); the fourth collimating lens group and the fifth collimating lens group have the same structure and both include an optically connected meniscus lens and a double convex lens; The core diameter of the optical fiber is 0.6 mm and the numerical aperture is 0.

22. The F number of the fourth collimating lens group is 2.2, the aperture is 20 mm, and the focal length is 44 mm. The lenses of the fourth collimating lens group and the fifth collimating lens group both include two quartz lenses with a total length of 26 mm.

10. The Raman temperature and humidity profile laser radar optical system according to claim 1, characterized in that: The spot diameters of the receiving telescope (1), the color separation system (2), the nitrogen Raman / water Raman channel system (3) and the grating spectroscopic system (4) are all better than 52 μm.

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