CN102937586A - Laser radar based water-in-cloud raman scattering full-spectrum measurement system and method thereof - Google Patents

Abstract

The invention discloses a Raman scattering full-spectrum measurement system for water in clouds based on laser radar, which includes a laser emitting device, a laser receiving device, a spectrum resolution device, a photoelectric detection device, a data acquisition device and a double-pulse trigger device. The emission device includes a laser, a beam expander and a reflector; the spectrum resolution device includes an optical fiber, an aspheric mirror, a broadband filter, a grating spectrometer and a rotating platform; the photodetection device includes a photomultiplier that converts an optical signal into an electrical signal tube; the data acquisition device includes a photon counting card and a computer; the double-pulse trigger device includes an induction trigger module, a single-chip microcomputer and a gate control device. At the same time, the invention also discloses a laser radar-based Raman scattering full-spectrum measurement method for water in clouds. The invention takes the solid water and liquid water in the cloud as detection objects, and the whole system has a compact structure, is easy to control and adjust, and has high system stability.

Description

Raman scattering full-spectrum measurement system and method of cloud water based on lidar

technical field

The invention relates to a full-spectrum measurement system for Raman scattering of water in clouds, and more specifically, to a full-spectrum measurement system for Raman scattering of water in clouds based on laser radar and a measurement method thereof.

Background technique

Lidar and spectroscopy are increasingly used in atmospheric science. So far, the macro-observation technology of clouds has been relatively mature, and there are many methods such as manual observation, ceilometer, all-sky imager, weather radar, and satellite remote sensing. However, there are still relatively few observation methods for the microphysical characteristics of clouds. As far as continuous observation is concerned, millimeter-wave radar is currently recognized as an effective detection device. However, compared with millimeter-wave radar, lidar has more advantages in terms of spatial resolution and mode of action, and lidar has relatively mature technologies, simple system, low operation and maintenance costs, and has certain advantages in application and promotion.

Lidars have been developed for observation of different phases of water in clouds, including polarization lidar, water vapor differential absorption lidar, Raman lidar, etc. Among them, the polarization lidar only qualitatively describes the phase state of water in the cloud. To accurately obtain the water content of different phases in the cloud requires the knowledge of the Raman scattering spectrum of water. In addition, compared with water vapor differential absorption lidar, Raman lidar has advantages in terms of system complexity and cost.

At present, the existing Raman lidar in China mainly measures the water vapor content in the atmosphere, while inside the cloud, the phases of water are mainly solid water and liquid water. So far, there is no lidar system that detects solid and liquid water in clouds.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a Raman scattering full-spectrum measurement system for water in clouds based on lidar, which takes solid water and liquid water in clouds as detection objects.

At the same time, the invention also provides a laser radar-based Raman scattering full-spectrum measurement method for water in clouds.

In order to solve the above technical problems, the present invention provides a laser radar-based full-spectrum measurement system for water Raman scattering in clouds, including a laser emitting device, a laser receiving device, a spectrum resolution device, a photoelectric detection device and a data acquisition device,

The laser emitting device is arranged below the cloud to be measured, and includes a laser, a beam expander and a reflector. The centers of the laser, the beam expander and the reflector are arranged on the same straight line, and the laser emits The emitted laser pulse enters the entrance of the beam expander, and the beam expander emits the laser pulse to the reflector, and the reflector emits the laser pulse vertically into the air, and hits the measured cloud body superior;

The laser receiving device is a telescope, collects echo signals reflected by the measured cloud body, and sends the echo signals to the spectral resolution device;

The spectral resolution device includes an optical fiber, an aspheric mirror, a broadband filter, a grating spectrometer and a rotating platform, and the outlet of the optical fiber, the center of the aspheric mirror, the broadband filter and the grating spectrometer are arranged on the same line Above, the entrance of the optical fiber receives the echo signal output by the telescope, and the echo signal passes through the optical fiber, the aspheric mirror, the broadband filter and the grating spectrometer in sequence, and then is transmitted to the Photoelectric detection device;

The photodetection device includes a photomultiplier tube, the input end of which is in signal communication with the grating spectrometer, and when the grating spectrometer is in an open state, receives the spectral signal sent by the grating spectrometer and forwards the signal to the data acquisition device;

The data acquisition device includes a photon counting card and a computer, the input end of the photon counting card is connected with the output end signal of the photomultiplier tube, receives the signal of the photomultiplier tube for sampling and counting, and transmits the data to the computer.

The technical solution of the present invention is further defined as follows: the system also includes a double-pulse trigger device, the double-pulse trigger device includes an induction trigger module, a single-chip microcomputer and a gate control device, and the induction trigger module is arranged in the laser emission range of the laser connected with the single-chip microcomputer, and transmit electrical signals to the single-chip microcomputer; the output terminal of the single-chip microcomputer is connected with the photon counting card, and transmits a double-pulse trigger signal to the photon counting card to control the opening of the photon counting card and closing; the single-chip microcomputer is connected to the photomultiplier tube through the gate control device, and transmits a gating signal to the photomultiplier tube to control the opening and closing of the photomultiplier tube. Single-chip microcomputer 15 is the single-chip microcomputer of AM89 series, and preferred model is AT89S52 or AT89LS52.

Further, the spectrum resolution device further includes a rotating platform, and the grating spectrometer is fixedly arranged on the rotating platform.

Further, the grating spectrometer adopts a plane reflection grating, and the angular interval between adjacent spectral lines of the plane reflection grating and the number of grooves per millimeter of the grating are determined by formulas (1), (2), (3), (4), (5) Determine:

$\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k</span>}\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

δθ=D _θ ·δλ (4)

$\mathrm{<span\; class="notranslate">\; \&Delta;\&theta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; Nd</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Where d is the grating constant; N is the number of grating grooves per millimeter, the unit is millimeter; λ is the selected reference wavelength, the unit is millimeter; θ is the diffraction angle of the first-order spectral line, the unit is degree; k is the spectral level ; D _θ is the angular dispersion power of the grating, the unit is degree; δθ is the angular interval of adjacent spectral lines, the unit is degree; δλ is the wavelength difference of adjacent spectral lines, the unit is mm; Δθ is the half-angle width of the spectral line, the unit is Spend.

Further, the laser is a Nd:YAG laser.

Further, the central wavelength of the broadband filter is 405nm, and the passband bandwidth is 40nm.

Further, the time resolution of the photon counting card is 100 ns, the distance resolution is 15 m, and the maximum counting rate is 200 MHz.

Another technical solution disclosed by the present invention is: a lidar-based Raman scattering full-spectrum measurement method for water in clouds, which is characterized in that it is carried out according to the following steps:

(1) The laser emits laser pulses. After expanding and collimating the laser light through the beam expander, the laser pulse beam is vertically injected into the air through the mirror, and hits the cloud to be measured;

(2) After the induction trigger module positioned near the laser senses the laser, the signal is transmitted to the single-chip microcomputer. The single-chip microcomputer 15 is a single-chip microcomputer of the AM89 series, and the preferred model is AT89S52 or AT89LS52; Open the door of the photomultiplier tube before the Raman scattering signal arrives after the laser is emitted, and prepare to receive the Raman scattering signal;

(3) When the first pulse of the double-pulse trigger signal arrives in step (2), the Raman scattering signal and the background light signal are received by the telescope, and the received signal is transmitted into the optical fiber, and the optical wave is collimated by the optical fiber;

(iv) The light wave collimated by the optical fiber is collimated-focused by an aspheric mirror and becomes parallel light; after the parallel light passes through a broadband filter to filter out some interference noise, it reaches the rotating grating spectrometer, and the grating spectrometer rotates at a certain angle The resolution and wavelength interval detect the Raman echo signal and transmit the signal to the photomultiplier tube;

(5) The photomultiplier tube converts the received optical signal into an electrical signal and sends it to the photon counting card, which samples and counts the received electrical signal, converts the analog signal into a digital signal and transmits the digital signal to the computer, The computer processes and stores the received digital signal;

(vi) When the second pulse of the double-pulse trigger signal arrives in step (ii), the background light signal is received by the telescope, and the received signal is transmitted into the optical fiber. After the optical fiber collimates the light wave, step (iv) and step (v) are performed ;

(vii) Subtract the signal obtained in step (v) from the signal obtained in step (v) to obtain the characteristic information of the spectrum.

9. the water Raman scattering full-spectrum measurement method based on lidar in the cloud according to claim 1, is characterized in that, described grating spectrometer adopts plane reflective grating, and the adjacent spectral line angle interval of described plane reflective grating and The number of grooves per millimeter of grating is determined by formulas (1), (2), (3), (4), (5):

$\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k</span>}\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

δθ=D _θ ·δλ (4)

$\mathrm{<span\; class="notranslate">\; \&Delta;\&theta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; Nd</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Where d is the grating constant; N is the number of grating grooves per millimeter, the unit is millimeter; λ is the selected reference wavelength, the unit is millimeter; θ is the diffraction angle of the first-order spectral line, the unit is degree; k is the spectral level ; D _θ is the angular dispersion power of the grating, the unit is degree; δθ is the angular interval of adjacent spectral lines, the unit is degree; δλ is the wavelength difference of adjacent spectral lines, the unit is mm; Δθ is the half-angle width of the spectral line, the unit is Spend.

The beneficial effect of the present invention is: compared with existing laser radar system, the water Raman scattering full-spectrum measurement system and method thereof based on laser radar proposed by the present invention have the following advantages:

①Take the solid water and liquid water in the cloud as the detection object, and obtain the Raman scattering full-spectrum distribution curve of the water in the cloud, which will help to further obtain the water content in different phases in the cloud, which is of great significance to the study of cloud microphysical characteristics.

② Combining the laser radar system and the grating spectrometer has the advantages of high spectral resolution and relatively small volume.

③Double-pulse trigger technology is adopted to minimize the influence of background light.

④ The grating spectrometer is driven by an electric rotating platform to ensure a fixed diffraction angle of the light entering the grating spectrometer, which is convenient for the reception of the photoelectric detection system.

⑤ The whole system is compact in structure, easy to control and adjust, and has high system stability.

Description of drawings

Fig. 1 is the structural representation of the water Raman scattering full-spectrum measurement system based on laser radar in the cloud of the present invention;

Fig. 2 is the signal diagram of the gating signal issued by the single-chip microcomputer of the present invention;

FIG. 3 is a signal diagram of a double-pulse trigger signal issued by a single-chip microcomputer according to the present invention.

In the picture:

1. Laser; 2. Beam expander; 3. Mirror; 4. Telescope; 5. Optical fiber; 6. Filter; 7. Aspheric mirror; 8. Grating spectrometer; 9. Rotating platform; 10. Photomultiplier tube; 11. Photon counting card; 12. Computer; 13. PMT gate control; 14. Induction trigger module; 15. Single-chip microcomputer.

Detailed ways

Example 1

A lidar-based Raman scattering full-spectrum measurement system for water in clouds provided in this embodiment has a structure as shown in Figure 1, including a laser emitting device, a laser receiving device, a spectral resolution device, a photoelectric detection device, a data acquisition device and Double pulse trigger device.

The laser emitting device is arranged below the measured cloud, and includes a laser 1, a beam expander 2 and a reflector 3, and the centers of the laser 1, the beam expander 2 and the reflector 3 are arranged on the same straight line superior. The laser pulse emitted by the laser 1 enters the entrance of the beam expander 2, and the beam expander 2 transmits the laser pulse to the reflector 3, and the reflector 3 transmits the laser pulse vertically to In the air, and hit the measured cloud body. The laser 1 is a Nd:YAG laser, the wavelength of the pulsed laser beam is 355nm, the single pulse energy is 70mJ, the pulse width is <7ns, the repetition frequency is 20Hz, and the divergence angle is ≤1mrad. Beam expander 2 uses 30 times beam expander. The inclination angle of the reflector 3 is 45 degrees. The function of the laser 1 is to emit laser pulses, the function of the beam expander 2 is to collimate the beam and reduce the divergence angle of the laser, and the function of the mirror 3 is to make the laser pulse beam vertically shoot into the air.

Described laser receiving device is the telescope 4 that collects Raman scattering echo signal, and telescope 4 adopts Meade LX200 telescope, and telescope aperture is 400mm, and focal length is 2000mm. Use the telescope 4 to collect the backscattered echoes of the laser radar and the background light when there is no laser.

The spectrum resolution device includes an optical fiber 5 , an aspheric mirror 6 , a broadband filter 7 , a grating spectrometer 8 and a rotating platform 9 . The outlet of the optical fiber 5, the center of the aspheric mirror 6, the broadband filter 7 and the grating spectrometer 8 are arranged on the same straight line, and the entrance of the optical fiber 5 receives the echo signal output by the telescope 4 After the echo signal passes through the optical fiber 5, the aspheric mirror 6, the broadband filter 7 and the grating spectrometer 8 in sequence, it is transmitted to the photoelectric detection device.

The numerical aperture of the optical fiber 5 adopts NA=0.12, and the optical fiber is bendable, which improves the flexibility of the system. The grating spectrometer 8 is fixedly arranged on the rotating platform 9 to detect Raman echo signals with a certain angular resolution and wavelength interval. The central wavelength of the broadband filter 7 is 405nm, and the passband bandwidth is 40nm.

The grating spectrometer 8 adopts a planar reflective grating for spectrally separating the Raman scattering signals obtained after separation, and the minimum wavelength interval that the grating can distinguish is 0.05 nm. The angular interval between adjacent spectral lines of the plane reflective grating and the number of grooves per mm of the grating are determined by formulas (1), (2), (3), (4), and (5):

$\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k</span>}\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

δθ=D _θ ·δλ (4)

$\mathrm{<span\; class="notranslate">\; \&Delta;\&theta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; Nd</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Where d is the grating constant; N is the number of grating grooves per millimeter, the unit is millimeter; λ is the selected reference wavelength, the unit is millimeter; θ is the diffraction angle of the first-order spectral line, the unit is degree; k is the spectral level ; D _θ is the angular dispersion power of the grating, the unit is degree; δθ is the angular interval of adjacent spectral lines, the unit is degree; δλ is the wavelength difference of adjacent spectral lines, the unit is mm; Δθ is the half-angle width of the spectral line, the unit is Spend.

A planar grating with a width of 15cm and a grating constant d of 1/1200mm is selected. Calculated by the formula, the angular interval δθ of adjacent spectral lines is 0.23′, and the half-angle width Δθ of each spectral line is 0.009′.

The electric rotating platform 9 is used to drive the grating spectrometer 8 to rotate, so as to ensure that optical signals with a certain wavelength interval enter the grating spectrometer at a fixed diffraction angle. In order to adapt to the angular interval corresponding to the minimum wavelength difference that the grating spectrometer can distinguish, the TRB-m series electric rotary platform is selected. The diameter of the table is 200mm, the transmission ratio is 1:360, and the resolution of the whole step of the motor is 0.01° ( Running in 10 subdivision state, the resolution is 0.01°÷10=0.001°=0.06′), and the adjustment range is ±15°.

The functions of the spectral resolution device are:

①Converge the optical echo signal into the optical fiber 5, and then use the aspheric mirror 6 to collimate the backscattered signal.

② Use broadband filter 7 to filter out part of the background noise and elastic scattering noise.

③Use the rotating grating spectrometer 8 to perform spectral separation to realize spectral scanning.

The photodetection device includes a photomultiplier tube 10 that converts optical signals into electrical signals, and the response wavelength range of the photomultiplier tube 10 is 200nm-900nm, which is in a normally closed state, and its input terminal communicates with the grating spectrometer 8 through signals, When the photomultiplier tube 10 is in an open state, it receives the spectral signal sent by the grating spectrometer 8; the output end of the photomultiplier tube 10 communicates with the data acquisition device.

The function of the photodetection device is to use the photomultiplier tube 10 to convert light signals into electrical signals. Use PMT gating 13 to suppress the effects of sunlight, stray light in the environment. Usually, the photomultiplier tube is turned off, and the photomultiplier tube is opened to receive the Raman scattering signal after the laser is emitted and before the Raman scattering signal arrives.

Described data acquisition device comprises photon counting card 11 and computer 12, and the input end of described photon counting card 11 is connected with the output end of described photomultiplier tube 10 by signal, receives the electric signal of described photon multiplier tube 10 to sample and Counting: the input end of the computer 12 is connected to the output end of the photon counting card 11 to receive the sampling and counting signals of the photon counting card 11 and analyze and store them. The output end of the computer 12 is connected with the control end of the rotary platform 9 to control the rotation of the rotary platform 9 .

The photon counting card 11 uses a P7882 photon counting card with a time resolution of 100 ns, a distance resolution of 15 m, and a maximum count rate of 200 MHz.

The function of described data acquisition device is:

① Sampling and counting the output signal of the detector.

② Record and save the variation of the intensity of the water Raman scattering echo signal with the wavelength and display it on the computer 12 .

The double-pulse triggering device includes an inductive trigger module 14, a single-chip microcomputer 15 and a gate control device 13. The inductive trigger module 14 is arranged in the laser emission range of the laser 1, connected with the single-chip microcomputer 15, and sensed to the laser. 1. After emitting the laser, transmit electrical signal to the microcontroller 15. Single-chip microcomputer 15 is the single-chip microcomputer of AM89 series, and preferred model is AT89S52 or AT89LS52.

The single-chip microcomputer 15 communicates bidirectionally with the computer 12; the output end of the single-chip microcomputer 15 is connected with the photon counting card 11, and is connected with the photomultiplier tube 10 through the gate control device 13 for ① transfer gate control signal to the photomultiplier tube 10 to control the opening and closing of the photomultiplier tube 10; Turn on the photomultiplier tube 10 and the photon counting card 11 during the Mann scattering echo, and collect the light intensity signal including the Raman scattering signal; the second pulse turns on the photomultiplier tube 10 and the photon counting card 11 when there is no laser, and collects the background light intensity signal.

The working method of the water Raman scattering full-spectrum measurement system based on lidar in the cloud of the present invention is to carry out according to the following steps:

(1) The laser 1 emits laser pulses, after the beam expander 2 expands and collimates the laser light, the laser pulse beam is vertically injected into the air through the reflector 3, and hits the cloud body to be measured.

(2) After the induction trigger module 14 positioned near the laser 1 senses the laser light, it transmits the signal to the single-chip microcomputer 15, and the single-chip microcomputer 15 issues a gate control signal and a double pulse trigger signal. The signal diagram of the gate control signal is as shown in Figure 2. The signal diagram of the double-pulse trigger signal is shown in FIG. 3 . The gate control signal opens the gate of the photomultiplier tube 10 before the Raman scattering signal arrives after the laser is emitted, and is ready to receive the Raman scattering signal.

(3) When the first pulse of the double-pulse trigger signal arrives in step (2), the Raman scattering signal and the background light signal are received by the telescope 4, and the received signal is passed into the optical fiber 5, and the optical wave is collimated by the optical fiber 5 .

(iv) The light waves collimated by the optical fiber 5 are collimated-focused by the aspheric mirror 6 and become parallel light; the parallel light reaches the rotating grating spectrometer 8 after the broadband filter 7 filters out part of the interference noise, and the grating The spectrometer 8 detects the Raman echo signal with a certain angular resolution and wavelength interval, and transmits the signal to the photomultiplier tube 10 .

The grating spectrometer can be set to measure 1000 pulses per rotation to improve the signal-to-noise ratio.

(5) The photomultiplier tube 10 converts the received optical signal into an electrical signal, and sends it to the photon counting card 11, which samples and counts the electrical signal received by the photon counting card 11, converts the analog signal into a digital signal and transmits the digital signal to The computer 12 processes and stores the received digital signal.

(vi) When the second pulse of the double-pulse trigger signal arrives in step (ii), the background light signal is received by the telescope 4, and the received signal is transmitted to the optical fiber 5, and after the optical fiber 5 collimates the light wave, step (iv) is performed and step (v).

(vii) Subtract the signal obtained in step (v) from the signal obtained in step (v) to obtain the characteristic information of the spectrum. In addition to the above-mentioned embodiments, the present invention can also have other implementations. All technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the present invention.

Claims (9)

1. Raman scattering full-spectrum measurement system for cloud water based on lidar, including laser emitting device, laser receiving device, spectral resolution device, photoelectric detection device and data acquisition device, The laser emitting device is arranged under the measured cloud, including a laser (1), a beam expander (2) and a mirror (3), the laser (1), the beam expander (2) and the The centers of the mirrors (3) are arranged on the same straight line, the laser pulse emitted by the laser (1) enters the entrance of the beam expander (2), and the beam expander (2) emits the laser pulse to the reflector (3), the reflector (3) vertically emits the laser pulse into the air, and hits the measured cloud body; The laser receiving device is a telescope (4), which collects echo signals reflected by the measured cloud body, and sends the echo signals to the spectral resolution device; The spectral resolution device includes an optical fiber (5), an aspheric mirror (6), a broadband filter (7), a grating spectrometer (8) and a rotating platform (9), the outlet of the optical fiber (5), the aspheric mirror (6), the centers of the broadband filter (7) and the grating spectrometer (8) are arranged on the same straight line, and the entrance of the optical fiber (5) receives the echo signal output by the telescope (4), After the echo signal passes through the optical fiber (5), the aspheric mirror (6), the broadband filter (7) and the grating spectrometer (9) in sequence, it is transmitted to the photoelectric detection device; The photodetection device includes a photomultiplier tube (10), the input end of which is in signal communication with the grating spectrometer (8), and when the grating spectrometer (8) is in an open state, it receives the signal sent by the grating spectrometer (8). The spectral signal and forward the signal to the data acquisition device; The data acquisition device includes a photon counting card (11) and a computer (12), the input end of the photon counting card (11) is connected to the output end of the photomultiplier tube (10) for signal connection, and receives the photon counting tube (10) the signal is sampled and counted, and the data is sent to the computer (12). 2. the cloud water Raman scattering full-spectrum measurement system based on laser radar according to claim 1, is characterized in that, described system also comprises double-pulse triggering device, and described double-pulse triggering device comprises induction triggering module (14 ), a single-chip microcomputer (15) and a gate control device (13), the induction trigger module (14) is set within the laser emission range of the laser (1), connected with the single-chip microcomputer (15), and transmits an electrical signal to the The single-chip microcomputer (15); the output terminal of the single-chip microcomputer (15) is connected to the photon counting card (11), and a double-pulse trigger signal is transmitted to the photon counting card (11) to control the photon counting card (11) The opening and closing of the single-chip microcomputer (15) is connected with the photomultiplier tube (10) through the gate control device (13), and transmits a gating signal to the photomultiplier tube (10) to control the photomultiplier Opening and closing of tube (10). 3. The lidar-based Raman scattering full-spectrum measurement system for water in clouds according to claim 1, wherein the spectral resolution device further includes a rotating platform (9), and the grating spectrometer (8) is fixed on the rotating platform (9). 4. The lidar-based Raman scattering full-spectrum measurement system for water in clouds according to claim 1, wherein the grating spectrometer (8) adopts a plane reflection grating, and the adjacent spectral lines of the plane reflection grating The angular spacing and the number of grooves per millimeter of grating are determined by formulas (1), (2), (3), (4), (5): $\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$ $\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k</span>}\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$ ${\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$ δθ=D _θ ·δλ(4) $\mathrm{<span\; class="notranslate">\; \&Delta;\&theta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; Nd</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$ Where d is the grating constant; N is the number of grating grooves per millimeter, the unit is millimeter; λ is the selected reference wavelength, the unit is millimeter; θ is the diffraction angle of the first-order spectral line, the unit is degree; k is the spectral level ; D _θ is the angular dispersion power of the grating, the unit is degree; δθ is the angular interval of adjacent spectral lines, the unit is degree; δλ is the wavelength difference of adjacent spectral lines, the unit is mm; Δθ is the half-angle width of the spectral line, the unit is Spend. 5. The lidar-based full-spectrum measurement system for Raman scattering of water in clouds according to claim 1, characterized in that the laser (1) is a Nd:YAG laser. 6. The lidar-based Raman scattering full-spectrum measurement system for water in clouds according to claim 1, characterized in that, the central wavelength of the broadband filter (7) is 405 nm, and the passband bandwidth is 40 nm. 7. The lidar-based Raman scattering full-spectrum measurement system for water in clouds according to claim 1, wherein the time resolution of the photon counting card (11) is 100 ns, the distance resolution is 15 m, and the maximum The counting rate is 200MHz. 8. The Raman scattering full-spectrum measurement method of water in clouds based on laser radar, is characterized in that, carries out according to the following steps: (1) The laser (1) emits laser pulses, after the beam expander (2) expands and collimates the laser light, the laser pulse beam is vertically injected into the air through the mirror (3), and hits the cloud to be measured; (2) After sensing the laser, the induction trigger module (14) located near the laser (1) transmits the signal to the single-chip microcomputer (15), and the single-chip microcomputer (15) sends a gate control signal and a double-pulse trigger signal, and the gate control signal is sent out by the laser Open the door of the photomultiplier tube (10) before the arrival of the rear Raman scattering signal, and prepare to receive the Raman scattering signal; (3) When the first pulse of the double-pulse trigger signal arrives in step (2), the Raman scattering signal and the background light signal are received by the telescope (4), and the received signal is transmitted to the optical fiber (5), and the optical fiber (5) ) to collimate the light waves; (iv) The light wave collimated by the optical fiber (5) is collimated-focused by the aspheric mirror (6) and becomes parallel light; the parallel light reaches the rotating grating after filtering part of the interference noise by the broadband filter (7) a spectrometer (8), the grating spectrometer (8) detects Raman echo signals with a certain angular resolution and wavelength interval, and transmits the signals to a photomultiplier tube (10); (5) The photomultiplier tube (10) converts the received optical signal into an electrical signal, and sends it to the photon counting card (11), and the photon counting card (11) samples and counts the received electrical signal, and converts the analog signal into a digital signal and transmit the digital signal to the computer (12), and the computer (12) processes and stores the received digital signal; (vi) When the second pulse of the double-pulse trigger signal arrives in step (ii), the background light signal is received by the telescope (4), and the received signal is transmitted to the optical fiber (5), and the light wave is aligned by the optical fiber (5). After that, step (iv) and step (v) are carried out; (vii) Subtract the signal obtained in step (v) from the signal obtained in step (v) to obtain the characteristic information of the spectrum. 9. The lidar-based Raman scattering full-spectrum measurement method for water in clouds according to claim 1, wherein the grating spectrometer (8) adopts a plane reflection grating, and the adjacent spectral lines of the plane reflection grating The angular spacing and the number of grooves per millimeter of grating are determined by formulas (1), (2), (3), (4), (5): $\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$ $\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k</span>}\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$ ${\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$ δθ=D _θ ·δλ(4) $\mathrm{<span\; class="notranslate">\; \&Delta;\&theta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; Nd</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$ Where d is the grating constant; N is the number of grating grooves per millimeter, the unit is millimeter; λ is the selected reference wavelength, the unit is millimeter; θ is the diffraction angle of the first-order spectral line, the unit is degree; k is the spectral level ; D _θ is the angular dispersion power of the grating, the unit is degree; δθ is the angular interval of adjacent spectral lines, the unit is degree; δλ is the wavelength difference of adjacent spectral lines, the unit is mm; Δθ is the half-angle width of the spectral line, the unit is Spend.

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