A polarization laser radar system for stereoscopic environment monitoring

Abstract

The invention relates to the technical field of remote sensing monitoring of atmospheric environment, and discloses a three-dimensional environment monitoring polarization laser radar system, comprising a laser emission system, which is used for emitting laser into the air; a rotating polarization device, which can rotate around an optical axis; a lens, which is located at the rear side of the rotating polarization device and converges the laser scattered by aerosol in the air and passing through the rotating polarization device to a spectroscope; the spectroscope divides the laser into a CCD and a detector in proportion; the CCD, when the rotating polarization device rotates to work, is used for detecting the distribution of transverse polarization profiles; the detector, when the rotating polarization device rotates to work, is used for detecting the distribution of longitudinal polarization profiles; when the rotating polarization device does not rotate to work, and the polarization directions of the lasers emitted by the rotating polarization device and the laser emission system are consistent, the detector is used for detecting the extinction profile; the measurement of the extinction profile, the transverse polarization profile and the longitudinal polarization profile is realized without multiple detectors, thus saving the number of channels and the cost.

Description

Technical Field

[0001] The present invention relates to the technical field of remote sensing monitoring of atmospheric environment, and in particular to a polarization laser radar system for stereoscopic environment monitoring. Background Art

[0002] like Figure 2 As shown in the figure, the current distribution detection of atmospheric particulate matter generally adopts the Mie scattering principle of laser active detection. A laser beam is emitted into the atmosphere, and the laser will scatter with the aerosol molecules in the air. A telescope is used to receive the scattered echo signal at the backscattering position. The intensity of the backscattered echo signal will be different at different distances and different aerosol extinction coefficients. Mie scattering laser radar can analyze the aerosol extinction profile at different heights, but it cannot distinguish the type of pollutant. Figure 3 As shown, in the prior art, a laser radar with polarization detection is also used. The emitted laser is linearly polarized light. The polarization ratio of the emitted laser is known. The vertical and parallel channels of the returning light are separated by PBS, and the light intensity in two directions is detected by photomultiplier tube PMT respectively, so that the depolarization ratio can be calculated. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a three-dimensional environment monitoring polarization lidar system, which can simultaneously measure the aerosol extinction profile, transverse polarization profile and longitudinal polarization profile through remote sensing without multiple detectors.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A three-dimensional environment monitoring polarization laser radar system, comprising:

[0006] A laser emission system, used to emit laser into the air;

[0007] Rotating polarizer, which can rotate around the optical axis;

[0008] A lens is located at the rear side of the rotating polarizer and converges the laser light scattered by the aerosol in the air and passing through the rotating polarizer to the beam splitter;

[0009] Beam splitter, which divides the laser into CCD and detector in proportion;

[0010] CCD, when the rotating polarization device rotates, the CCD is used to detect the distribution of the transverse polarization profile;

[0011] The detector is used to detect the distribution of the longitudinal polarization profile when the rotating polarization device rotates and works; when the rotating polarization device does not rotate and the polarization direction of the laser emitted by the rotating polarization device and the laser emission system is consistent, the detector is used to detect the extinction profile.

[0012] Furthermore, the rotating polarization device is a linear polarization device.

[0013] Furthermore, the beam splitter divides the laser light to the CCD and the detector in a ratio of 50:50.

[0014] Furthermore, the laser emission system includes a laser, a first reflector, and a second reflector. The first reflector adjusts the spot of the laser emitted by the laser to the middle position of the second reflector, and by adjusting the angle of the second reflector, the direction of the emitted laser is parallel to the optical axis direction of the rotating polarization device.

[0015] Compared with the prior art, the beneficial technical effects of the present invention are:

[0016] The polarization device of the present invention is rotatable and is placed at the front end of the receiving system for vertical incidence. By rotating the polarization device in a rotating state and a non-rotating state, the measurement of the extinction profile, the transverse polarization profile, and the longitudinal polarization profile can be achieved without the need for multiple detectors, thereby saving the number of channels and costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the radar system of the present invention;

[0018] Figure 2 It is a schematic diagram of an atmospheric environment monitoring device in the prior art;

[0019] Figure 3 It is a schematic diagram of atmospheric environment monitoring equipment in the prior art. DETAILED DESCRIPTION

[0020] A preferred embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0021] The polarization laser radar system of the present invention can not only remotely sense the distribution of aerosols in the air, but also identify the type of pollutants, and identify the distribution categories of pollutants from the vertical and horizontal directions.

[0022] The vertical judgment category refers to the degree of particle depolarization at different height profiles. Experimental observations have found that particles with different ellipticity have different depolarization effects. Spherical particles basically do not change the polarization characteristics of the laser, while the depolarization characteristics of non-spherical particles are very obvious. Spherical particles are generally secondary particles (local pollution) formed by oxidation, adsorption, and condensation of gaseous pollutants such as VOCs; non-spherical particles are mostly sand and dust, which are transported externally. Vertical judgment can analyze the type of particulate pollutants at vertical heights.

[0023] The horizontal category judgment is realized based on the optical imaging characteristics and the principle of polarized light analysis. The object plane is imaged on the surface of CCD3 through lens 2. CCD3 records the light intensity information and simultaneously rotates the polarization device 1 to record the polarization characteristics at different angles. The polarization information at different positions on the object plane can be solved according to the Stokes equation, thereby judging the horizontal polarization distribution characteristics and thus judging the category of the material.

[0024] like Figure 1 As shown, the stereoscopic environment monitoring polarization laser radar system in the present invention includes a laser, a first reflector 8, a second reflector 9, a rotating polarization device 1, a lens 2, a beam splitter 10, a CCD 3, a pinhole diaphragm 4, a collimator 5, a filter 6, a detector 7, an analog-to-digital conversion module, a main control, and a host computer. The lens is located at the rear side of the rotating polarization device.

[0025] The laser, the first reflector 8, and the second reflector 9 constitute a laser emission system; the rotating polarizer 1, the lens 2, the beam splitter 10, the CCD 3, the pinhole diaphragm 4, the collimator 5, the filter 6, and the detector 7 constitute a receiving system. The detector 7 is a photomultiplier tube (PMT).

[0026] The light emitted by the laser is reflected by two reflectors and then emitted. The first reflector 8 adjusts the laser spot to the middle position of the second reflector 9. By adjusting the angle of the second reflector 9, the emitted laser beam is coaxial with the receiving system. The laser emitted into the air reacts with the aerosol and scatters, and first enters the rotating polarizer 1. The rotating polarizer 1 is a linear polarizer that can rotate around the optical axis. The polarized light passing through the rotating polarizer is received and converged by the lens 2, and split by the beam splitter 50:50. A part of it enters the CCD3 for imaging. When the rotating polarizer 1 rotates and works, the CCD3 can detect the distribution of the transverse polarization profile; the other part passes through the beam splitter 10, the pinhole diaphragm 4, the collimator 5, and the filter 6, and reaches the surface of the detector 7. When the rotating polarizer 1 rotates and works, this part detects the distribution of the longitudinal polarization profile; when the rotating polarizer 1 does not rotate and works, and the polarization direction of the rotating polarizer 1 is consistent with that of the emitted laser, the detector 7 is used to detect the extinction profile. The specific workflow is as follows.

[0027] Polarization detection process:

[0028] (1) The laser is turned on, and the laser enters the atmosphere and is scattered;

[0029] (2) The rotating polarizer 1 rotates and the scattered light enters the receiving system and changes in intensity;

[0030] (3) The photomultiplier tube and CCD3 collect light signals and perform photoelectric conversion, which are then collected by the digital-to-analog conversion module and entered into the host computer for calculation;

[0031] (4) Output longitudinal polarization profile distribution and transverse polarization profile distribution.

[0032] Extinction detection process:

[0033] (1) The polarization device 1 is rotated to the same polarization direction as the outgoing laser;

[0034] (2) The laser is turned on, and the laser enters the atmosphere and is scattered;

[0035] (3) The scattered light enters the receiving system and changes in intensity;

[0036] (4) The photomultiplier tube collects the light signal and performs photoelectric conversion, which is then collected by the digital-to-analog conversion module and sent to the host computer for calculation;

[0037] (5) Output extinction profile.

[0038] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

[0039] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A three-dimensional environment monitoring polarization laser radar detection method, characterized in that: The polarization lidar system used includes: A laser emission system, used to emit laser into the air; Rotating polarizer, which can rotate around the optical axis; A lens is located at the rear side of the rotating polarizer and converges the laser light scattered by the aerosol in the air and passing through the rotating polarizer to the beam splitter; Beam splitter, which divides the laser into CCD and detector in proportion; CCD, when the rotating polarization device rotates, the CCD is used to detect the distribution of the transverse polarization profile; The detector is used to detect the distribution of the longitudinal polarization profile when the rotating polarization device rotates; when the rotating polarization device does not rotate and the polarization direction of the laser emitted by the rotating polarization device is consistent with that of the laser emission system, the detector is used to detect the extinction profile; The polarization detection process includes: (1) The laser is turned on, and the laser enters the atmosphere and is scattered; (2) The rotating polarizer rotates and the scattered light enters the receiving system and changes in intensity; (3) The photomultiplier tube and CCD3 collect light signals and perform photoelectric conversion, which are then collected by the digital-to-analog conversion module and entered into the host computer for calculation; (4) Outputting longitudinal polarization profile distribution and transverse polarization profile distribution; The extinction detection process includes: (1) Rotate the polarization device to the same polarization direction as the outgoing laser; (2) The laser is turned on, and the laser enters the atmosphere and is scattered; (3) The scattered light enters the receiving system and changes in intensity; (4) The photomultiplier tube collects the light signal and performs photoelectric conversion, which is then collected by the digital-to-analog conversion module and sent to the host computer for calculation; (5) Output extinction profile.

2. The method for detecting a three-dimensional environment monitoring polarization laser radar according to claim 1, characterized in that: The rotating polarization device is a linear polarization device.

3. The method for detecting a three-dimensional environment monitoring polarization laser radar according to claim 1, characterized in that: The beam splitter splits the laser light to the CCD and the detector in a 50:50 ratio.

4. The method for detecting a three-dimensional environment monitoring polarization laser radar according to claim 1, characterized in that: The laser emission system includes a laser, a first reflector, and a second reflector. The first reflector adjusts the spot of the laser emitted by the laser to the middle position of the second reflector. By adjusting the angle of the second reflector, the direction of the emitted laser is parallel to the optical axis direction of the rotating polarization device.

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