Add-Drop filter-based high spectral resolution atmosphere laser radar
By using Add-Drop filters to separate aerosol and molecular scattered signals in hyperspectral resolution lidar, the problem of insufficient line width of narrowband optical filters is solved, and high-precision optical parameters for atmospheric aerosols and molecules are achieved Measurement.
Patent Information
- Application Number
- CN202411384358.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2024-12-27
AI Technical Summary
When the existing high-spectral resolution atmospheric lidar is separated from aerosol and molecular scattered signals, the line width of the narrowband optical filter is insufficient, making it difficult to effectively distinguish and separate aerosol and molecular scattered signals, which affects the optical of atmospheric aerosol and molecules. Parameter measurement accuracy.
The Add-Drop filter is used as a narrowband optical filter, and the spectral peak is locked through a narrow linewidth laser and a laser frequency stabilization system. Combined with an optical telescope and a bandpass optical color filter, the meter scattering and Rayleigh scattering signals in the atmosphere are separated. And use a multi-channel photodetection system to convert it into electrical signals for data acquisition and processing.
High-precision separation and measurement of aerosol and molecular scattered signals are achieved, optical parameters of atmospheric aerosol and molecules are derived, and measurement accuracy and signal-to-noise ratio are improved.
Smart Images
Figure FT_1 
Figure FT_2 
Figure FT_3
Abstract
Description
Technical Field
[0001] The invention relates to a high spectral resolution atmospheric laser radar based on an Add-Drop filter, and more specifically to a high spectral resolution atmospheric laser radar using an Add-Drop filter as a narrow-band optical filter. Background Art
[0002] When the laser is transmitted in the atmosphere, it will produce Mie scattering with the aerosols in the atmosphere and Rayleigh scattering with the molecules in the atmosphere. The spectral width of the aerosol Mie scattering is basically the same as the laser line width; the spectral width (full width at half maximum) of the molecular Rayleigh scattering is in the GHz range. Therefore, a laser with a line width smaller than the Rayleigh scattering spectral width is used as the laser radar light source, and a narrow-band optical filter can be used to directly separate the aerosol scattering and the molecular scattering in the spectrum, thereby obtaining high-precision optical parameters of atmospheric aerosols and molecules. At present, the narrow-band optical filters used in high-spectral-resolution atmospheric lidars include Fabry–Pérot interferometers, molecular (atomic) filters, etc.
[0003] The Add-Drop filter consists of three parts: Bus waveguide, Dropping waveguide, and coupling unit between Bus waveguide and Dropping waveguide. Light is input from the input port of Bus waveguide, and most of the light is output from the output port of Bus waveguide with almost no attenuation. When the wavelength of light meets the resonance wavelength of the coupling unit, the light of this wavelength is coupled from Bus waveguide to Dropping waveguide and output from the forward or backward port of Dropping waveguide. Therefore, the output of Bus waveguide is equivalent to optical band-stop filter, and the output of Dropping waveguide is equivalent to optical bandpass filter.
[0004] Add-Drop filters are currently mainly used in optical communications, biosensors and other fields. Summary of the invention
[0005] The object of the present invention is to provide a high spectral resolution atmospheric laser radar based on an Add-Drop filter, wherein the Add-Drop filter serves as a narrow-band optical filter.
[0006] The invention comprises a narrow line width laser, a laser frequency stabilization system, an optical circulator, an optical telescope, a band pass optical color filter, an Add-Drop filter, a multi-channel photoelectric detection system, and a data acquisition and processing system.
[0007] The output wavelength of the narrow linewidth laser is locked to the spectral peak of the Add-Drop filter by a laser frequency stabilization system. The frequency-stabilized laser is coupled into an optical telescope after passing through an optical circulator and collimated into parallel light. The parallel light is emitted into the atmosphere after passing through a bandpass optical filter. The backscattered signal light of atmospheric molecules and aerosols passes through a bandpass optical filter and an optical telescope, and is output by the optical circulator and enters the Add-Drop filter.
[0008] The Add-Drop filter separates the Mie scattering and Rayleigh scattering in the atmospheric echo. The Add-Drop filter Bus waveguide outputs the atmospheric Rayleigh scattering, and the Add-Drop filter Dropping waveguide outputs the atmospheric Mie scattering. The filtered atmospheric Mie scattering and Rayleigh scattering are converted into corresponding electrical signals using a multi-channel photoelectric detection system and imported into the data acquisition and processing system.
[0009] Because the atmospheric Mie scattering and Rayleigh scattering models are accurately known, the atmospheric Mie scattering and Rayleigh scattering intensities can be calculated using the Mie scattering signal and Rayleigh scattering signal filtered out by the Add-Drop filter, and then the corresponding optical parameters of atmospheric aerosols and molecules can be derived.
[0010] The line width of the narrow line width laser is smaller than the spectrum width of the Add-Drop filter. The free spectrum range of the Add-Drop filter is larger than the atmospheric Rayleigh scattering spectrum width. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention.
[0012] Figure 1 This is the Add-Drop filter structure diagram of the present invention Figure 2 This is the spectrum characteristic diagram of the Add-Drop filter of the present invention Figure 3 This is the structure diagram of the high spectral resolution atmospheric laser radar based on Add-Drop filter of the present invention Figure 4 The Add-Drop filter spectrum, atmospheric Mie scattering and Rayleigh scattering spectrum of the present invention are Figure 5 The atmospheric Mie scattering signal and the residual Rayleigh scattering signal filtered out by the Add-Drop filter of the present invention are Figure 6 is the atmospheric Rayleigh scattering signal filtered out by the Add-Drop filter of the present invention In the figure: 1. Bus waveguide of Add-Drop filter, 2. Dropping waveguide of Add-Drop filter, 3. Coupling unit of Add-Drop filter, 4. Bus waveguide input port of Add-Drop filter, 5. Bus waveguide output port of Add-Drop filter, 6. Dropping waveguide backward output port of Add-Drop filter, 7. Dropping waveguide forward output port of Add-Drop filter, 8. Bandpass spectrum output from Dropping waveguide backward or forward output port of Add-Drop filter, 9. Bandstop spectrum output from Bus waveguide output port of Add-Drop filter, 10. Spectral width (full width at half maximum) of Add-Drop filter, 11. Free spectral range of Add-Drop filter, 12. Narrow linewidth laser, 13. Laser frequency stabilization system, 14. Optical circulator, 15. Optical telescope, 16. Bandpass optical filter, 17. Add-Drop filter, 18. Multi-channel photoelectric detection system, 19. Data acquisition and processing system, 20. Bandpass optical filter spectrum, 21. Atmospheric Mie scattering, 22. Atmospheric Rayleigh scattering, 23. Atmospheric Rayleigh scattering line width (full width at half maximum), 24. Atmospheric Mie scattering filtered out by Add-Drop filter, 25. Residual Rayleigh scattering signal filtered out by Add-Drop filter, 26. Atmospheric Rayleigh scattering signal filtered out by Add-Drop filter. DETAILED DESCRIPTION
[0013] The purpose of the present invention is to provide a high spectral resolution atmospheric laser radar with an Add-Drop filter to solve the technical problems in the related fields. In order to make the technical problems and technical solutions to be solved by the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.
[0014] The Add-Drop filter structure of the present invention is shown in FIG. Figure 1 As shown, the Add-Drop filter spectral characteristics are shown in Figure 2 shown.
[0015] The Add-Drop filter consists of three parts: a Bus waveguide (1), a Dropping waveguide (2), and a coupling unit (3) between the Bus waveguide and the Dropping waveguide. Light is input from the input port (4) of the Bus waveguide, and most of the light is output from the output port (5) of the Bus waveguide with almost no attenuation. When the wavelength of light meets the resonance wavelength of the coupling unit (3), the light of this wavelength is coupled from the Bus waveguide (1) to the Dropping waveguide (2) and output from the backward output port (5) or the forward output port (6) of the Dropping waveguide. Therefore, the backward output port (5) or the forward output port (6) of the Dropping waveguide is equivalent to an optical bandpass filter, and the corresponding spectral characteristic is (8); the output port (4) of the Bus waveguide is equivalent to an optical bandstop filter, and the corresponding spectral characteristic is (9). The spectral width of the Add-Drop filter corresponding to (8) and (9) is (10), and the free spectral range of the corresponding Add-Drop filter is (11).
[0016] The structure of the high spectral resolution atmospheric laser radar based on Add-Drop filter of the present invention is as follows: Figure 3 shown.
[0017] A narrow linewidth laser (12) is used as a light source, and the laser wavelength is locked by a laser frequency stabilization (13) system. The frequency-stabilized laser passes through an optical circulator (14) and is coupled into an optical telescope (15) and collimated into parallel light. The parallel light passes through a bandpass optical filter (16) and is emitted into the atmosphere. The backscattered signal light of atmospheric molecules and aerosols passes through the bandpass optical filter (16) and the optical telescope (15), and is output by the optical circulator (14) and enters an Add-Drop filter (17).
[0018] The Add-Drop filter (17) separates Mie scattering and Rayleigh scattering in the atmospheric echo. The output port (5) of the Bus waveguide of the Add-Drop filter (17) outputs atmospheric Rayleigh scattering, and the forward output port (7) or the backward output port (6) of the Dropping waveguide of the Add-Drop filter outputs atmospheric Mie scattering. The filtered Mie scattering and Rayleigh scattering are converted into corresponding electrical signals by using a multi-channel photoelectric detection system (18) and imported into a data acquisition and processing system (19).
[0019] The Add-Drop filter spectrum, atmospheric Mie scattering and Rayleigh scattering spectrum of the present invention are as follows: Figure 4 shown.
[0020] The laser wavelength is locked to Figure 4The Add-Drop filter (17) is at λ0. The central wavelengths of atmospheric Mie scattering (21) and atmospheric Rayleigh scattering (22) are also at λ0. The present invention requires that the line width of the narrow line width laser is smaller than the spectral width (10) of the Add-Drop filter. The free spectral range (11) of the Add-Drop filter is larger than the spectral width (23) of the atmospheric Rayleigh scattering. The spectral characteristic corresponding to the bandpass optical filter (16) is (20), which is used to filter out background light.
[0021] Figure 5 The atmospheric Mie scattering signal (24) and the residual Rayleigh scattering signal (25) are filtered out using the bandpass spectral characteristics (8) of the Add-Drop filter (17).
[0022] Figure 6 It is the atmospheric Rayleigh scattering signal (26) filtered out by using the band-stop spectral characteristic (9) of the Add-Drop filter (17).
[0023] Because the bandpass spectrum characteristics (8) of the Add-Drop filter (17) are accurately known, and the theoretical models of laser atmospheric Mie scattering and Rayleigh scattering are also accurately known, the atmospheric Mie scattering signal (24), the residual Rayleigh scattering signal (25) and the atmospheric Rayleigh scattering signal (26) can be used to calculate the atmospheric Mie scattering and atmospheric Rayleigh scattering intensities.
[0024] In conclusion, Figure 3 The high spectral resolution atmospheric lidar based on Add-Drop filter can directly measure the intensity of atmospheric aerosol scattering and atmospheric molecular scattering, and obtain high-precision optical parameters of atmospheric aerosols and molecules.
[0025] It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Those skilled in the art should take the specification as a whole, and the technical solutions in the various embodiments can also be appropriately combined to form other implementations that can be understood by those skilled in the art.
Claims
1. A high spectral resolution atmospheric laser radar based on Add-Drop filter, characterized by: It consists of narrow linewidth laser, laser frequency stabilization system, optical circulator, optical telescope, bandpass optical filter, Add-Drop filter, multi-channel photoelectric detection system, data acquisition and processing system; The output wavelength of the narrow linewidth laser is locked on the spectrum peak of the Add-Drop filter by using a laser frequency stabilization system; the frequency-stabilized laser is coupled into an optical telescope after passing through an optical circulator and collimated into parallel light; the parallel light is emitted into the atmosphere after passing through a bandpass optical filter; the backscattered signal light of atmospheric molecules and aerosols passes through the bandpass optical filter and the optical telescope, is output by the optical circulator, and enters the Add-Drop filter; The Add-Drop filter separates the Mie scattering and Rayleigh scattering in the atmospheric echo. The Add-Drop filter Bus waveguide outputs the atmospheric Rayleigh scattering. The Add-Drop filter Dropping waveguide outputs the atmospheric Mie scattering. The filtered atmospheric Mie scattering and Rayleigh scattering are converted into corresponding electrical signals by using a multi-channel photoelectric detection system and imported into the data acquisition and processing system. Because the atmospheric Mie scattering and Rayleigh scattering models are accurately known, the atmospheric Mie scattering and Rayleigh scattering intensities can be calculated using the Mie scattering signal and Rayleigh scattering signal filtered out by the Add-Drop filter, and then the corresponding optical parameters of atmospheric aerosols and molecules can be derived.
2. The high spectral resolution atmospheric laser radar based on Add-Drop filter according to claim 1, characterized in that: The linewidth of a narrow-linewidth laser is smaller than the spectral width of an Add-Drop filter.
3. The high spectral resolution atmospheric laser radar based on Add-Drop filter according to claim 1, characterized in that: The free spectral range of the Add-Drop filter is larger than the atmospheric Rayleigh scattering spectrum width.