A method for obtaining a mid-infrared dual-wavelength differential absorption laser radar detection light source

Abstract

The application belongs to the field of laser frequency conversion, and particularly relates to a method for obtaining a mid-infrared dual-wavelength differential absorption laser radar detection light source. Pump laser with a wavelength of 1319 nm emitted by a pump laser source is normally injected from one end of a Raman cell, the Raman cell is filled with a Raman active gas medium, the pump laser injected into the Raman cell interacts with the Raman active gas medium, and then is normally emitted from the other end of the Raman cell, and dual-wavelength Raman laser with wavelengths of 3480 nm and 3519 nm is output; or, pump laser with a wavelength of 1064 nm emitted by a pump laser source is normally injected from one end of a Raman cell, and dual-wavelength Raman laser with wavelengths of 2132 nm and 2147 nm is obtained. The application can conveniently obtain a light source of a mid-infrared dual-wavelength differential absorption laser radar.

Description

Technical Field

[0001] This invention belongs to the field of laser frequency conversion, specifically a method for obtaining a mid-infrared dual-wavelength differential absorption lidar detection light source, which can be applied to related fields with special requirements for laser output wavelength, such as lidar detection of atmospheric composition. Background Technology

[0002] Differential absorption lidar is a powerful tool for detecting atmospheric pollutants. This type of lidar requires a dual-wavelength output laser, which uses the backscattered wave signals of the two wavelengths emitted by the laser in the atmosphere to perform differential calculations to obtain the concentration of ozone in the atmosphere.

[0003] An optical parametric oscillator (OPO) made of zinc germanium phosphorus (ZPG) crystal material can achieve tunable mid-to-far-infrared laser output. Stimulated Raman spectroscopy (SMR) is a laser frequency conversion method, especially gas-medium SMR, which is inexpensive, can withstand high peak power pulsed laser pumping, and avoids the problem of damage to the conversion medium. Therefore, gas-medium SMR technology has important applications in certain specific fields. Summary of the Invention

[0004] The purpose of this invention is to provide a method for obtaining a mid-infrared dual-wavelength differential absorption lidar detection light source, which obtains simultaneously output target dual-wavelength mid-infrared lasers through stimulated Raman frequency conversion in a gas medium.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] The present invention provides a method for obtaining a mid-infrared dual-wavelength differential absorption lidar detection light source:

[0007] A pump laser with a wavelength of 1319 nm emitted from a pump laser source is injected normally into one end of a Raman cell, which is filled with a Raman-active gas medium. The pump laser injected into the Raman cell interacts with the Raman-active gas medium and is then emitted normally from the other end of the Raman cell, outputting a dual-wavelength Raman laser with wavelengths of 3480 nm and 3519 nm.

[0008] Wherein: a quarter-wave plate is provided in the optical path between the pump laser source and the Raman cell. The pump laser with a wavelength of 1319nm emitted by the pump laser source enters the Raman cell normally from one end after passing through the quarter-wave plate. In order to maximize the output of dual-wavelength Raman laser of 3480nm and 3519nm, the rotation angle of the quarter-wave plate needs to be optimized. The angle between the fast axis direction of the crystal of the quarter-wave plate and the polarization direction of the laser is between 35° and 55°, that is, changing the polarization state of the pump laser. Elliptically polarized pump laser can obtain balanced output of dual-wavelength Raman laser of 3480 and 3519nm.

[0009] To maximize the output of dual-wavelength Raman lasers at 3480nm and 3519nm, the gas pressure of the Raman-active gas medium in the Raman cell needs to be optimized, i.e., the density of the Raman-active gas medium inside the Raman cell needs to be changed. The gas pressure of the Raman-active gas medium inside the Raman cell is 1.2 to 2.0 MPa at room temperature; the Raman-active gas is hydrogen.

[0010] A focusing lens is provided in the optical path between the pump laser source and the Raman cell. In order to maximize the output of dual-wavelength Raman lasers of 3480nm and 3519nm, the focal length of the focusing lens needs to be optimized, that is, the focusing lens with a different focal length is replaced. The focal length of the focusing lens is 1.5 to 2.5m.

[0011] Another method of obtaining a mid-infrared dual-wavelength differential absorption lidar detection source according to the present invention is as follows:

[0012] A pump laser with a wavelength of 1064 nm emitted from a pump laser source is injected normally into one end of a Raman cell, which is filled with a Raman-active gas medium. The pump laser injected into the Raman cell interacts with the Raman-active gas medium and is then emitted normally from the other end of the Raman cell, resulting in a dual-wavelength Raman laser with wavelengths of 2132 nm and 2147 nm.

[0013] A quarter-wave plate is provided in the optical path between the pump laser source and the Raman cell. The pump laser with a wavelength of 1064nm emitted by the pump laser source enters the Raman cell normally from one end after passing through the quarter-wave plate. In order to maximize the output of 2132nm and 2147nm dual-wavelength Raman laser, the rotation angle of the quarter-wave plate needs to be optimized. The angle between the fast axis direction of the crystal of the quarter-wave plate and the polarization direction of the laser is between 35° and 55°, that is, changing the polarization state of the pump laser. Elliptically polarized pump laser can obtain balanced output of 2132nm and 2147nm dual-wavelength Raman laser.

[0014] To maximize the output of dual-wavelength Raman lasers at 2132nm and 2147nm, the gas pressure of the Raman-active gas medium in the Raman cell needs to be optimized, i.e., the density of the Raman-active gas medium inside the Raman cell needs to be changed. The gas pressure of the Raman-active gas medium inside the Raman cell is 0.8 to 1.6 MPa at room temperature; the Raman-active gas is hydrogen.

[0015] A focusing lens is provided in the optical path between the pump laser source and the Raman cell. In order to maximize the output of 2132nm and 2147nm dual-wavelength Raman laser, the focal length of the focusing lens needs to be optimized, that is, the focusing lens with a different focal length is replaced. The focal length of the focusing lens is 1.3 to 1.8m.

[0016] The Raman cell has a Raman cell window A installed at one end and a Raman cell window B installed at the other end. The normal injection is the pump laser entering through a plane perpendicular to the Raman cell window A at one end of the Raman cell, and the normal exit is the laser exiting through a plane perpendicular to the Raman cell window B at the other end of the Raman cell.

[0017] The pump laser source is a pump laser, which uses a solid-state Nd:YAG laser with an output wavelength of 1319nm or 1064nm. A 45-degree reflecting mirror A, a 45-degree reflecting mirror B, a focusing lens, and a quarter-wave plate are sequentially arranged in the optical path between the pump laser and one end of the Raman cell. The 45-degree reflecting mirror B is located below and perpendicular to the 45-degree reflecting mirror A. The Raman cell is a hollow tubular container. A Raman cell window A is installed at one end of the Raman cell, and a Raman cell window B is installed at the other end. The surface of Raman cell window A is coated with a laser antireflection film corresponding to the pump laser wavelength, and the surface of Raman cell window B is coated with a laser antireflection film corresponding to the Raman laser wavelength. A pressure gauge for reading the gas pressure inside the Raman cell and a gas release valve for reducing the gas pressure inside the Raman cell are installed on the Raman cell. The Raman cell is connected to a Raman active gas bottle via a gas pipeline, and a valve is installed on the gas pipeline.

[0018] The advantages and positive effects of this invention are as follows:

[0019] This invention provides a convenient light source for obtaining mid-infrared dual-wavelength differential absorption lidar, which can convert 1319nm wavelength laser light to around 3.5μm and generate dual-wavelength laser light of 3480nm and 3519nm, with a phase difference of 32cm between the two wavelengths. -1 Furthermore, the method of this invention can also convert 1064nm wavelength laser light into dual-wavelength Raman laser light of 2132nm and 2147nm, achieving relatively high peak power, generating laser pulse widths in the nanosecond range, and single-pulse energy reaching the hundreds of millijoules level. The device used in the frequency conversion method is inexpensive, simple in structure, and easy to operate. Attached Figure Description

[0020] Figure 1 A schematic diagram of the apparatus for implementing the method of the present invention;

[0021] Wherein: 1 is the pump laser, 2 is the 45-degree reflecting mirror A, 3 is the 45-degree reflecting mirror B, 4 is the focusing lens, 5 is the quarter-wave plate, 6 is the Raman cell, 7 is the Raman cell window A, 8 is the Raman cell window B, 9 is the pressure gauge, 10 is the gas release valve, 11 is the hydrogen valve, and 12 is the hydrogen cylinder. Detailed Implementation

[0022] The invention will now be described in further detail with reference to the accompanying drawings.

[0023] The apparatus for implementing the method of obtaining a mid-infrared dual-wavelength differential absorption lidar detection source according to the present invention includes a pump laser source, a wavelength converter, and a gas filling system. The wavelength converter includes a 45-degree reflector A2, a 45-degree reflector B3, a focusing lens 4, a quarter-wave plate 5, and a Raman cell 6. The pump laser source, the 45-degree reflector A2, the 45-degree reflector B3, the focusing lens 4, and the quarter-wave plate 5 are all disposed outside the Raman cell 6. The pump laser source is a pump laser 1, which uses a solid-state Nd:YAG laser with an output wavelength of 1319nm or 1064nm. The 45-degree reflector A2, the 45-degree reflector B3, the focusing lens 4, and the quarter-wave plate 5 are sequentially arranged on the optical path between the pump laser 1 and one end of the Raman cell 6. The 45-degree reflector B3 is located below the 45-degree reflector A2 and is perpendicular to the 45-degree reflector A2. The Raman cell 6 is a hollow tubular container capable of withstanding high pressure. One end of the Raman cell 6 has a Raman cell window A7, and the other end has a Raman cell window B8. The surface of Raman cell window A7 is coated with a laser antireflection film corresponding to the pump laser wavelength, and the surface of Raman cell window B8 is coated with a laser antireflection film corresponding to the Raman laser wavelength. The gas filling system includes a Raman active gas cylinder and valves. The Raman active gas cylinder is connected to the interior of the Raman cell 6 via a gas pipeline, and a valve is installed on the gas pipeline between the Raman active gas cylinder and the Raman cell 6. The Raman active gas cylinder fills the Raman cell 6 with high-pressure gas. A pressure gauge 9 for reading the gas pressure inside the Raman cell 6 and a gas release valve 10 for reducing the gas pressure inside the Raman cell 6 are installed on the Raman cell 6.

[0024] Example 1

[0025] like Figure 1 As shown, in this embodiment, the pump laser 1 outputs a solid-state Nd:YAG laser with a wavelength of 1319nm. The Raman active gas bottle is a hydrogen bottle 12, and the valve on the gas pipeline is a hydrogen valve 11. The hydrogen bottle 12 injects hydrogen into the Raman cell 6 through the gas pipeline.

[0026] A 1319nm solid-state Nd:YAG laser pumps hydrogen gas to generate Raman lasers at 3480nm and 3519nm. These two wavelengths can be used as a differential absorption lidar source for detecting NO2 gas in the atmosphere. The 1319nm pump laser emitted by pump laser 1 passes through a quarter-wave plate 5 and is then injected normally into one end of the Raman cell 6. To maximize the output of the 3480nm and 3519nm dual-wavelength Raman laser, the rotation angle of the quarter-wave plate 6 needs to be optimized. The angle between the fast axis of the quarter-wave plate crystal and the polarization direction of the laser is between 35° and 55°, i.e., changing the polarization state of the pump laser. Elliptically polarized pump lasers can achieve a balanced output of 3480nm and 3519nm dual-wavelength Raman lasers. Lasers are a type of electromagnetic wave. Although electromagnetic waves are relatively abstract, their wave nature can be described in a way similar to mechanical waves (or water waves), that is, expressed by the cosine equation in trigonometric functions. The vibration direction is perpendicular to the propagation direction of the light wave, and this vibration direction can be understood as the polarization direction. Ordinary light polarization occurs in any 360-degree direction perpendicular to its propagation direction, or in other words, its polarization direction is random. However, lasers are different; they can be understood as a unified, special type of light wave with a consistent vibration direction. This unified vibration direction is called the laser's polarization direction. The anti-reflection coating on the surface of Raman cell window A7 is for anti-reflection of the 1319nm pump laser, while the anti-reflection coating on the surface of Raman cell window B8 is for anti-reflection of dual-wavelength Raman lasers at 3480nm and 3519nm.

[0027] The specific steps are as follows:

[0028] Step 1: Hydrogen gas is introduced into the Raman cell 6 through the cooperation of gas release valve 10, pressure gauge 9, and hydrogen cylinder 12. The hydrogen gas pressure is 1.2 to 2.0 MPa at room temperature. In this embodiment, the hydrogen gas pressure is 1.5 MPa.

[0029] Step 2: Pump laser 1 emits a pump laser with a wavelength of 1319nm. Taking the central axis of the pump laser beam emitted by pump laser 1 as the axis, after being reflected by 45-degree reflectors A2 and B3, it passes through focusing lens 4 and quarter-wave plate 5, and enters Raman cell 6 through Raman cell window A7. The pump laser in Raman cell 6 interacts with hydrogen gas, realizing wavelength conversion, and finally passes through Raman cell window B8 and is output outside Raman cell 6, thus generating Raman lasers of 3480nm and 3519nm. In order to maximize the output of 3480nm and 3519nm dual-wavelength Raman lasers, the focal length of focusing lens 4 needs to be optimized, that is, to replace it with a focusing lens with a different focal length. The focal length of the focusing lens is between 1.5 and 2.5m. In this embodiment, the focal length of the focusing lens is 2m, and the focal point of the focusing lens falls on the center of Raman cell 6.

[0030] Step 3: Use a spectrometer to collect the output Raman laser light. The Raman laser light is dispersed by a dispersive element and then collected.

[0031] Example 2

[0032] like Figure 1 As shown, in this embodiment, the pump laser 1 outputs a solid-state Nd:YAG laser with a wavelength of 1064 nm. The Raman active gas bottle is a hydrogen cylinder 12, and the valve on the gas pipeline is a hydrogen valve 11. Hydrogen gas is injected into the Raman cell 6 through the gas pipeline from the hydrogen cylinder 12. The 1064 nm solid-state Nd:YAG laser pumps hydrogen to generate Raman lasers at 2132 nm and 2147 nm. These two wavelengths can be used as pump sources for mid-infrared laser crystals. The pump laser emitted by pump laser 1, with a wavelength of 1064 nm, passes through a quarter-wave plate 5 and is then incident normally into one end of the Raman cell 6. To maximize the output of dual-wavelength Raman lasers at 2132 nm and 2147 nm, the rotation angle of the quarter-wave plate 6 needs to be optimized. The angle between the fast axis of the quarter-wave plate crystal and the polarization direction of the laser is between 35° and 55°, i.e., changing the polarization state of the pump laser. Elliptically polarized pump lasers can achieve balanced output of dual-wavelength Raman lasers at 2132 nm and 2147 nm. The anti-reflection coating deposited on the surface of Raman cell window A7 is for the 1064 nm pump laser, while the anti-reflection coating deposited on the surface of Raman cell window B8 is for the dual-wavelength Raman lasers at 2132 nm and 2147 nm.

[0033] The specific steps are as follows:

[0034] Step 1: Hydrogen gas is introduced into the Raman cell 6 through the cooperation of gas release valve 10, pressure gauge 9, and hydrogen cylinder 12. The hydrogen gas pressure is 0.8-1.6 MPa at room temperature. In this embodiment, the hydrogen gas pressure is 1 MPa.

[0035] Step two: Pump laser 1 emits a pump laser with a wavelength of 1064nm. Taking the central axis of the pump laser beam emitted by pump laser 1 as the axis, after being reflected by 45-degree reflectors A2 and B3, it passes through focusing lens 4 and quarter-wave plate 5, and enters Raman cell 6 through Raman cell window A7. The pump laser in Raman cell 6 interacts with hydrogen gas, realizing wavelength conversion, and finally passes through Raman cell window B8 and is output outside Raman cell 6, thus generating Raman lasers of 2132nm and 2147nm. In order to maximize the output of 2132nm and 2147nm dual-wavelength Raman lasers, the focal length of focusing lens 4 needs to be optimized, that is, to replace it with a focusing lens with a different focal length. The focal length of the focusing lens is 1.3 to 1.8m. In this embodiment, the focal length of the focusing lens is 1.5m.

[0036] Step 3: Use a spectrometer to collect the output Raman laser light. The Raman laser light is dispersed by a dispersive element and then collected.

[0037] To demonstrate that only the method of this invention can obtain the corresponding dual-wavelength Raman laser, several comparative examples are listed below:

[0038] Comparative Example 1

[0039] The process and conditions are the same as in Example 2, except that: Appendix Figure 1 The device shown uses the 1064nm wavelength output of an Nd:YAG solid-state laser as the pump source. If the Raman cell is filled with pure gaseous elements other than hydrogen, such as nitrogen (output wavelength 1415nm), methane (output wavelength 1543nm), or carbon dioxide (output wavelength 1248nm), then the device cannot achieve the output of dual-wavelength Raman lasers at 2132nm and 2147nm.

[0040] Comparative Example 2

[0041] The process and conditions are the same as in Example 2, except that: Appendix Figure 1 The device shown uses the 1064nm wavelength output of an Nd:YAG solid-state laser as the pump source. If a linearly vibrating laser (with the quarter-wave plate removed or rotated so that the angle between the fast axis of the crystal and the laser polarization direction is 0°) is used as the pump laser for hydrogen stimulated Raman spectroscopy, there will be no Raman laser output with dual wavelengths of 2132nm and 2147nm. Only Raman laser outputs of 1064nm and 1907nm can be obtained.

[0042] Comparative Example 3

[0043] The process and conditions are the same as in Example 2, except that: Appendix Figure 1 The device shown uses the 1064nm wavelength output of the Nd:YAG solid-state laser as the pump source. Increasing the hydrogen gas pressure to 3MPa will not produce the efficient 2132nm and 2147nm dual-wavelength Raman laser output, but will only produce 1064nm and 1907nm Raman laser output.

[0044] Comparative Example 4

[0045] The process and conditions are the same as in Example 2, except that: Appendix Figure 1 The device shown uses the 1064nm wavelength output of Nd:YAG solid-state laser as the pump source. If the focusing lens in Example 2 is replaced with a focusing lens with a focal length of f = 500mm, there will be no high-efficiency Raman laser output of 2132nm and 2147nm dual wavelengths. Only Raman laser output of 1064nm and 1907nm can be obtained.

[0046] Comparative Example 5

[0047] The process and conditions are the same as in Example 1, except that: Appendix Figure 1 The device shown uses the 1319nm wavelength output of an Nd:YAG solid-state laser as the pump source. If the Raman cell is filled with pure elemental gases other than hydrogen, such as nitrogen (output wavelength 1904nm), methane (output wavelength 2144nm), or carbon dioxide (output wavelength 1614nm), then the device cannot achieve dual-wavelength Raman laser output at 3480nm and 3519nm; the output laser wavelength is 1319nm.

[0048] Comparative Example 6

[0049] The process and conditions are the same as in Example 1, except that: Appendix Figure 1 The device shown uses the 1319nm wavelength output of an Nd:YAG solid-state laser as the pump source. Using a linearly vibrating laser (with the quarter-wave plate removed or rotated so that the angle between the fast axis of the crystal and the laser polarization direction is 0°) as the pump laser for hydrogen stimulated Raman spectroscopy will not achieve balanced output of dual-wavelength Raman lasers at 3480nm and 3519nm. The output laser wavelengths are 1319nm and 2918nm.

[0050] Comparative Example 7

[0051] The process and conditions are the same as in Example 1, except that: Appendix Figure 1 The device shown uses the 1319nm wavelength output of the Nd:YAG solid-state laser as the pump source. Increasing the hydrogen gas pressure to 4MPa will not produce the efficient dual-wavelength Raman laser output of 3480nm and 3519nm. The output laser wavelengths are 1319nm and 2918nm.

[0052] Comparative Example 8

[0053] The process and conditions are the same as in Example 1, except that: Appendix Figure 1 The device shown uses the 1319nm wavelength output of Nd:YAG solid-state laser as the pump source. By replacing the focusing lens in Example 1 with a focusing lens with a focal length of f = 300mm, there will be no dual-wavelength Raman laser output of 3480nm and 3519nm. The output laser wavelengths are 1319nm and 2918nm.

Claims

1. A method for obtaining a mid-infrared dual-wavelength differential absorption lidar detection light source, characterized in that: A pump laser with a wavelength of 1319 nm emitted from a pump laser source is injected normally into one end of a Raman cell, which is filled with a Raman-active gas medium. The pump laser injected into the Raman cell interacts with the Raman-active gas medium and is then emitted normally from the other end of the Raman cell, outputting a dual-wavelength Raman laser with wavelengths of 3480 nm and 3519 nm.

2. The method for obtaining a mid-infrared dual-wavelength differential absorption lidar detection source according to claim 1, characterized in that: A quarter-wave plate is provided in the optical path between the pump laser source and the Raman cell. The pump laser with a wavelength of 1319nm emitted by the pump laser source enters the Raman cell normally from one end after passing through the quarter-wave plate. In order to maximize the output of dual-wavelength Raman lasers of 3480nm and 3519nm, the rotation angle of the quarter-wave plate needs to be optimized. The angle between the fast axis direction of the crystal of the quarter-wave plate and the polarization direction of the laser is between 35° and 55°, that is, changing the polarization state of the pump laser. Elliptically polarized pump lasers can obtain balanced output of dual-wavelength Raman lasers of 3480 and 3519nm.

3. The method for obtaining a mid-infrared dual-wavelength differential absorption lidar detection source according to claim 1, characterized in that: To maximize the output of dual-wavelength Raman lasers at 3480nm and 3519nm, the gas pressure of the Raman-active gas medium in the Raman cell needs to be optimized, i.e., the density of the Raman-active gas medium inside the Raman cell needs to be changed. The gas pressure of the Raman-active gas medium inside the Raman cell is 1.2 to 2.0 MPa at room temperature; the Raman-active gas is hydrogen.

4. The method for obtaining a mid-infrared dual-wavelength differential absorption lidar detection source according to claim 1, characterized in that: A focusing lens is provided in the optical path between the pump laser source and the Raman cell. In order to maximize the output of dual-wavelength Raman lasers of 3480nm and 3519nm, the focal length of the focusing lens needs to be optimized, that is, the focusing lens with a different focal length is replaced. The focal length of the focusing lens is 1.5 to 2.5m.

5. A method for obtaining a mid-infrared dual-wavelength differential absorption lidar detection light source, characterized in that: A pump laser with a wavelength of 1064 nm emitted from a pump laser source is injected normally into one end of a Raman cell, which is filled with a Raman-active gas medium. The pump laser injected into the Raman cell interacts with the Raman-active gas medium and is then emitted normally from the other end of the Raman cell, resulting in a dual-wavelength Raman laser with wavelengths of 2132 nm and 2147 nm.

6. The method for obtaining a mid-infrared dual-wavelength differential absorption lidar detection source according to claim 5, characterized in that: A quarter-wave plate is provided in the optical path between the pump laser source and the Raman cell. The pump laser with a wavelength of 1064nm emitted by the pump laser source enters the Raman cell normally from one end after passing through the quarter-wave plate. In order to maximize the output of 2132nm and 2147nm dual-wavelength Raman laser, the rotation angle of the quarter-wave plate needs to be optimized. The angle between the fast axis direction of the crystal of the quarter-wave plate and the polarization direction of the laser is between 35° and 55°, that is, changing the polarization state of the pump laser. Elliptically polarized pump laser can obtain balanced output of 2132nm and 2147nm dual-wavelength Raman laser.

7. The method for obtaining a mid-infrared dual-wavelength differential absorption lidar detection light source according to claim 5, characterized in that: To maximize the output of dual-wavelength Raman lasers at 2132nm and 2147nm, the gas pressure of the Raman-active gas medium in the Raman cell needs to be optimized, i.e., the density of the Raman-active gas medium inside the Raman cell needs to be changed. The gas pressure of the Raman-active gas medium inside the Raman cell is 0.8 to 1.6 MPa at room temperature; the Raman-active gas is hydrogen.

8. The method for obtaining a mid-infrared dual-wavelength differential absorption lidar detection source according to claim 5, characterized in that: A focusing lens is provided in the optical path between the pump laser source and the Raman cell. In order to maximize the output of 2132nm and 2147nm dual-wavelength Raman laser, the focal length of the focusing lens needs to be optimized, that is, the focusing lens with a different focal length is replaced. The focal length of the focusing lens is 1.3 to 1.8m.

9. The method for obtaining a mid-infrared dual-wavelength differential absorption lidar detection source according to claim 1 or 5, characterized in that: The Raman cell has a Raman cell window A installed at one end and a Raman cell window B installed at the other end. The normal injection is the pump laser entering through a plane perpendicular to the Raman cell window A at one end of the Raman cell, and the normal exit is the laser exiting through a plane perpendicular to the Raman cell window B at the other end of the Raman cell.

10. The method for obtaining a mid-infrared dual-wavelength differential absorption lidar detection source according to claim 1 or 5, characterized in that: The pump laser source is a pump laser (1), which uses a solid-state Nd:YAG laser with an output wavelength of 1319nm or 1064nm; a 45-degree reflecting mirror A (2), a 45-degree reflecting mirror B (3), a focusing lens (4), and a quarter-wave plate (5) are sequentially arranged on the optical path between the pump laser (1) and one end of the Raman cell (6); the 45-degree reflecting mirror B (3) is located below the 45-degree reflecting mirror A (2) and is perpendicular to the 45-degree reflecting mirror A (2); the Raman cell (6) is a hollow tubular container, the Raman cell ( 6) has a Raman cell window A (7) installed at one end and a Raman cell window B (8) installed at the other end. The surface of the Raman cell window A (7) is coated with a laser antireflection film corresponding to the pump laser wavelength, and the surface of the Raman cell window B (8) is coated with a laser antireflection film corresponding to the Raman laser wavelength. The Raman cell (6) is equipped with a pressure gauge (9) for reading the gas pressure inside the Raman cell (6) and a gas release valve (10) for reducing the gas pressure inside the Raman cell (6). The Raman cell (6) is connected to a Raman active gas bottle through a gas pipeline, and a valve is installed on the gas pipeline.

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