CN102288970A - Method, system and detection machine for detecting atmospheric waveguide environment - Google Patents

Abstract

The present invention provides a method, system and detection machine for detecting the atmospheric waveguide environment, wherein the method includes: emitting laser light into a simulated atmospheric environment; acquiring the laser light to irradiate aerosol particles with different radii in the simulated atmospheric environment, generating The laser detection backscattered light signal; the scattered light signal after the laser detection is analyzed to obtain the backscattering characteristics of the laser detection of the aerosol particles with different radii; The characteristic parameters of the atmospheric waveguide are obtained based on the backscattering characteristics and the change of the atmospheric refractive index. The solution of the invention utilizes the laser to detect the atmospheric waveguide environment, and the detection has high real-time performance.

Description

Method, system and detector for detecting atmospheric waveguide environment

technical field

The invention relates to the field of atmospheric environment parameter detection, in particular to a method, system and detection machine for detecting atmospheric waveguide environmental parameters.

Background technique

Atmospheric waveguide is an atmospheric space that can make electromagnetic waves return and propagate in a meandering manner. Atmospheric waveguide environment will allow electromagnetic waves to achieve trans-horizon transmission with a small attenuation. In the ocean environment, due to the presence of various gases and water vapor, the propagation path of electromagnetic waves is curved. Radar can detect distances that are several times the normal observation distance. The goal is to achieve beyond-horizon detection and reception. The atmospheric waveguide environment will also cause potential blind spots or weak signal phenomena in the normal coverage area of microwave radar detection capabilities, and will also lead to more complex electromagnetic interference problems between equipment systems. According to the formation mechanism of atmospheric ducts, offshore atmospheric ducts can be mainly divided into: evaporation ducts and suspended atmospheric ducts.

The evaporation waveguide occurs on the ocean surface, and its formation mechanism is that the saturated water vapor pressure near the ocean surface rises to a certain height and suddenly decreases sharply, satisfying the condition that the vertical atmospheric refractive index gradient is less than -157n/km, resulting in the electromagnetic wave in the vertical direction. Propagation is constrained by the layered structure of the evaporation waveguide, and super-refraction occurs. The height of the evaporation waveguide layer in the vertical direction is generally between 5m and 50m. It has the characteristics of good stability, long duration, and long extension distance in the horizontal direction. The upper and lower walls of the suspended atmospheric duct layer are the atmosphere; however, the serious lack of observation data on the vast ocean and the long-term continuous large-scale observation are difficult to implement, which seriously restricts the research of atmospheric duct technology.

Traditional atmospheric waveguide detection methods usually use sounding rockets or balloons to obtain atmospheric parameters such as temperature, humidity, air pressure, and wind direction, calculate the refractive index of the atmosphere at different altitudes, obtain the vertical profile of the refractive index, and then judge the atmospheric waveguide. There is a situation to provide data support for trans-horizon transmission.

These traditional methods require long-distance and multi-point collection of atmospheric parameters, which are relatively poor in flexibility and real-time performance, and the data collection process is expensive.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method, a system and a detection machine for detecting the atmospheric waveguide environment, and the detection has high real-time performance.

In order to solve the above technical problems, an embodiment of the present invention provides a method for detecting an atmospheric duct environment, including:

Launch laser into simulated atmospheric environment;

Obtaining the laser detection backscattered light signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment;

Analyzing the scattered light signal after the laser detection to obtain the backscattering characteristics of the laser detection of the aerosol particles with different radii;

According to the backscattering characteristics of aerosol particles in different temperature, humidity and pressure environments and the change of atmospheric refractive index, the characteristic parameters of the atmospheric waveguide are obtained.

Wherein, the step of analyzing the scattered light signal after the laser detection to obtain the backscattering characteristics of the laser detection of the aerosol particles with different radii is as follows:

by the following formula $I_{\mathrm{sca}}={\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="HDA0000075572340000031.png,HDA0000075572340000041.png"\; state="\{\{state\}\}">I</figure-callout>}}_0\frac{{\mathrm{\&lambda;}}^2}{{8\mathrm{\&pi;}}^2{R}^2}I(\mathrm{\&theta;},\mathrm{\&phi;})$ The scattered light signal after the laser detection is analyzed, and the backscattering characteristics of the laser detection of the aerosols with different radii are obtained: aerosol particles generate backscattered light signals under the incident laser Large, the intensity of the backscattered light increases accordingly;

Among them, I ₀ is the intensity of incident light, λ is the laser wavelength, I _sca is the scattered light intensity at point P at a distance R from the center of the atmosphere O, is the angle-dependent scattered light intensity, where,

其中，I₁、I₂分别表示垂直和平行于散射平面的散射强度函数分量，S₁、S₂表示幅值函数，其无穷级数形式为： $S_1\left(\mathrm{\&theta;}\right)=\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{2n+1}{n(n+1)}[a_n{\mathrm{\&pi;}}_n\left(\cos \mathrm{\&theta;}\right)+b_n{\mathrm{\&tau;}}_n\left(\cos \mathrm{\&theta;}\right)]$

Among them, I ₁ and I ₂ represent the components of the scattering intensity function perpendicular to and parallel to the scattering plane, respectively, and S ₁ and S ₂ represent the amplitude function, whose infinite series form is: $S_1\left(\mathrm{\&theta;}\right)=\underset{\mathrm{no}=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{2\mathrm{no}+1}{\mathrm{no}(\mathrm{no}+1)}[a_{\mathrm{no}}{\mathrm{\&pi;}}_{\mathrm{no}}\left(\cos \mathrm{\&theta;}\right)+b_{\mathrm{no}}{\mathrm{\&tau;}}_{\mathrm{no}}\left(\cos \mathrm{\&theta;}\right)]$

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

Wherein, a _n and b _n are Mie scattering coefficients, and the Mie scattering coefficient is a function of the ratio parameter α (α=2πr/λ) of the single particle size r to the laser wavelength λ.

Among them, according to the backscattering characteristics of aerosol particles and the change of atmospheric refractive index in different temperature, humidity and pressure environments, the steps to obtain the characteristic parameters of the atmospheric waveguide are as follows:

According to the distribution characteristics of laser detection backscattered light signals generated by laser irradiation on aerosol particles with different radii in different temperature, humidity and pressure environments and when the vertical refractive index gradient of the atmosphere is less than -157N/KM, the characteristics of the atmospheric waveguide are obtained Parameters, wherein the atmospheric waveguide characteristic parameters include: the duration of the waveguide layer, the height of the waveguide layer, the horizontal extension range of the waveguide layer, the probability of the occurrence of the evaporation wave layer, and the meteorological and hydrological conditions for generating the evaporation waveguide.

Wherein, the wavelength of the laser is 1.064 μm, the radius of the aerosol particles ranges from 0.1 μm to 100 μm, the refractive index of the aerosol particles is 1.55, and the refractive index of the aerosol outer cladding water is 1.33.

Embodiments of the present invention also provide a system for detecting the atmosphere waveguide environment, including:

The detector is used to emit laser light into the simulated atmospheric environment, and obtain the laser detection backscattered light signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment;

A processor for analyzing the scattered light signal after the laser detection, to obtain the backscattering characteristics of the aerosol particles with different radii detected by the laser; and according to the backscattering characteristics of the aerosol particles in different temperature, humidity and pressure environments characteristics and changes in atmospheric refractive index to obtain the characteristic parameters of the atmospheric waveguide.

Wherein, the detection machine includes:

The laser emitting subsystem is used to emit laser light into the simulated atmospheric environment;

The optical signal receiving subsystem is used to obtain the laser detection backscattered optical signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment;

Wherein, the laser emission subsystem includes:

A pulsed laser for generating laser light with a pulse energy of 20mJ, a pulse width of 10ns, and a wavelength of 1.064μm; and

A transmitting antenna for transmitting the laser light generated by the pulsed laser into a simulated atmospheric environment;

Wherein, the optical signal receiving subsystem includes:

The receiving antenna is used to receive the laser detection backscattered light signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment;

a detector, configured to detect the backscattered light signal of the laser detection, and output a high-speed transient weak light signal;

A broadband low-noise amplifier, used to amplify the high-speed transient weak optical signal;

The avalanche photodiode bias booster is used to receive the high-speed transient weak light signal output by the detector and output it to the processor.

输入电流噪声小于

Wherein, the transconductance gain of the broadband low noise amplifier is above 1.5GHz, and the input voltage noise is less than

Input current noise is less than

Wherein, the avalanche photodiode bias booster includes: an avalanche photodiode, a digital temperature chip, a digital/analog converter and a microprocessor, wherein the microprocessor reads out the current The surface temperature value of the avalanche photodiode APD, using the temperature-bias compensation curve under the fixed gain of the APD, obtains the target bias voltage V _goal of the APD at the current temperature, and adjusts the current bias voltage V _control of the APD to the target bias voltage through the digital/analog converter V _goal .

9. The system according to claim 8, wherein the response time of the avalanche photodiode is 450 ps, and the noise current is

Wherein, the optical signal receiving subsystem also has a shielding device made of weak magnetic material.

Wherein, the weak magnetic material is metal aluminum with a thickness of 1.3 mm.

为与角度相关的散射光强度，其中，

其中，I₁、I₂分别表示垂直和平行于散射平面的散射强度函数分量，S₁、S₂表示幅值函数，其无穷级数形式为： $S_1\left(\mathrm{\&theta;}\right)=\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{2n+1}{n(n+1)}[a_n{\mathrm{\&pi;}}_n\left(\cos \mathrm{\&theta;}\right)+b_n{\mathrm{\&tau;}}_n\left(\cos \mathrm{\&theta;}\right)]$ Wherein, the processor passes the following formula $I_{\mathrm{sca}}={\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="HDA0000075572340000031.png,HDA0000075572340000041.png"\; state="\{\{state\}\}">I</figure-callout>}}_0\frac{{\mathrm{\&lambda;}}^2}{{8\mathrm{\&pi;}}^2{R}^2}I(\mathrm{\&theta;},\mathrm{\&phi;})$ The scattered light signal after the laser detection is analyzed, and the backscattering characteristics of the laser detection of the aerosols with different radii are obtained: aerosol particles generate backscattered light signals under the incident laser The intensity of the backscattered light increases accordingly; where I ₀ is the intensity of the incident light, λ is the wavelength of the laser, I _sca is the scattered light intensity at point P at a distance of R from the center of the atmosphere O,

is the angle-dependent scattered light intensity, where,

Among them, I ₁ and I ₂ represent the components of the scattering intensity function perpendicular to and parallel to the scattering plane, respectively, and S ₁ and S ₂ represent the amplitude function, whose infinite series form is: $S_1\left(\mathrm{\&theta;}\right)=\underset{\mathrm{no}=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{2\mathrm{no}+1}{\mathrm{no}(\mathrm{no}+1)}[a_{\mathrm{no}}{\mathrm{\&pi;}}_{\mathrm{no}}\left(\cos \mathrm{\&theta;}\right)+b_{\mathrm{no}}{\mathrm{\&tau;}}_{\mathrm{no}}\left(\cos \mathrm{\&theta;}\right)]$

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

Wherein, a _n and b _n are Mie scattering coefficients, and the Mie scattering coefficient is a function of the ratio parameter α (α=2πr/λ) of the single particle size r to the laser wavelength λ.

Embodiments of the present invention also provide a detection machine, comprising:

The laser emitting subsystem is used to emit laser light into the simulated atmospheric environment;

The optical signal receiving subsystem is used to obtain the laser detection backscattered optical signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment;

Wherein, the laser emission subsystem includes:

A pulsed laser, used to generate a laser with a pulse energy of 20mJ, a pulse width of 10ns, and a wavelength of 1.064μm; and a transmitting antenna, used to emit the laser generated by the pulsed laser into a simulated atmospheric environment;

Wherein, the optical signal receiving subsystem includes:

The receiving antenna is used to receive the laser detection backscattered light signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment;

a detector, configured to detect the backscattered light signal of the laser detection, and output a high-speed transient weak light signal;

A broadband low-noise amplifier, used to amplify the high-speed transient weak optical signal;

The avalanche photodiode bias booster is used to receive the high-speed transient weak light signal output by the detector and output it to a processor connected to the detector.

The beneficial effects of above-mentioned technical scheme of the present invention are as follows:

In the above scheme, by emitting laser light into the simulated atmospheric environment and obtaining the laser detection backlight scattering light signal, the backscattering characteristics of the aerosol particles in the simulated atmospheric environment are further obtained, and the atmospheric waveguide environment is detected in real time to obtain The characteristic parameters of the atmospheric duct, such as the thickness, extension range, and duration of the duct layer, provide atmospheric duct environmental data support for military activities such as atmospheric duct over-the-horizon detection. This method improves the accuracy of atmospheric waveguide forecasting, and solves the problem of inaccurate waveguide parameters provided by the method of forecasting refractive index by weather; this method has high sampling accuracy, large data volume, convenience and flexibility, and solves the problem of using radiosonde equipment to measure Harsh conditions, long delays in measurement results, and poor representation of horizontal distance expansion make up for the poor range and azimuth resolution of over-the-horizon radars and the unsatisfactory positioning accuracy.

Description of drawings

Fig. 1 is the flow chart of the method for detecting atmospheric waveguide environment of the present invention;

Figure 2 is a schematic diagram of the principle of laser detection of atmospheric waveguide;

Fig. 3 is the laser scattering model of a single particle;

Figure 4A and Figure 4B are the simulation results of laser light scattering of aerosols with different refractive indices;

Figure 5A and Figure 5B are the laser scattering simulation results of aerosols with different radii;

Fig. 6 is the laser emitting and optical signal receiving system of the laser detection system of the present invention;

Fig. 7 is the schematic circuit diagram of the laser detection system of the present invention;

Fig. 8 is a circuit schematic diagram of a broadband transconductance amplifier;

Fig. 9 is a structural block diagram of an adaptive numerical control bias boosting system;

Fig. 10 is the microprocessor work flow chart of self-adaptive numerical control bias voltage system;

Figure 11 is a schematic diagram of a laser detection experiment;

Fig. 12A, Fig. 12B, Fig. 12C are echo signal diagrams of laser detection experiments;

Figure 13A, Figure 13B, Figure 13C laser detection experiment echo signal diagram;

Fig. 14A, Fig. 14B, Fig. 14C and Fig. 14D are echo signal diagrams of laser detection experiments.

Detailed ways

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will describe in detail with reference to the drawings and specific embodiments.

The present invention aims at the problem that the traditional atmospheric waveguide detection method requires long-distance multi-point acquisition of atmospheric parameters, relatively poor flexibility and real-time performance, and high cost in the data acquisition process, and provides a method, system and detection machine for detecting the atmospheric waveguide environment. Real-time detection is high.

As shown in Figure 1, the method for detecting the atmospheric duct environment of the present invention includes:

Step 11, launching the laser into the simulated atmospheric environment;

Step 12, obtaining the laser detection backscattered light signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment;

Step 13, analyzing the scattered light signal after the laser detection to obtain the backscattering characteristics of the laser detection of the aerosol particles with different radii;

Step 14, according to the backscattering characteristics of the aerosol particles in different temperature, humidity and pressure environments and the change of the atmospheric refractive index, the characteristic parameters of the atmospheric waveguide are obtained.

The above scheme of the present invention emits laser light into the simulated atmospheric environment, and obtains the backscattering light signal of the laser detection, and further obtains the backscattering characteristics of the aerosol particles in the simulated atmospheric environment, and detects the atmospheric waveguide environment in real time, Obtain the characteristic parameters of the atmospheric duct such as the thickness, extension range and duration of the duct layer, and provide atmospheric duct environmental data support for military activities such as atmospheric duct over-the-horizon detection. This method improves the accuracy of atmospheric waveguide forecasting, and solves the problem of inaccurate waveguide parameters provided by the method of forecasting refractive index by weather; this method has high sampling accuracy, large data volume, convenience and flexibility, and solves the problem of using radiosonde equipment to measure Harsh conditions, long delays in measurement results, and poor representation of horizontal distance expansion make up for the poor range and azimuth resolution of over-the-horizon radars and the unsatisfactory positioning accuracy.

Further, in the above embodiment, step 13 is implemented based on the Mie scattering theory, specifically:

by the following formula $I_{\mathrm{sca}}=I_0\frac{{\mathrm{\&lambda;}}^2}{{8\mathrm{\&pi;}}^2{R}^2}I(\mathrm{\&theta;},\mathrm{\&phi;})$ The scattered light signal after the laser detection is analyzed, and the backscattering characteristics of the laser detection of the aerosols with different radii are obtained: aerosol particles generate backscattered light signals under the incident laser Large, the intensity of the backscattered light is enhanced accordingly;

为与角度相关的散射光强度，其中，Among them, I ₀ is the intensity of incident light, λ is the laser wavelength, I _sca is the scattered light intensity at point P at a distance R from the center of the atmosphere O,

is the angle-dependent scattered light intensity, where,

其中，I₁、I₂分别表示垂直和平行于散射平面的散射强度函数分量，S₁、S₂表示幅值函数，其无穷级数形式为： $S_1\left(\mathrm{\&theta;}\right)=\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{2n+1}{n(n+1)}[a_n{\mathrm{\&pi;}}_n\left(\cos \mathrm{\&theta;}\right)+b_n{\mathrm{\&tau;}}_n\left(\cos \mathrm{\&theta;}\right)]$

Among them, I ₁ and I ₂ represent the components of the scattering intensity function perpendicular to and parallel to the scattering plane, respectively, and S ₁ and S ₂ represent the amplitude function, whose infinite series form is: $S_1\left(\mathrm{\&theta;}\right)=\underset{\mathrm{no}=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{2\mathrm{no}+1}{\mathrm{no}(\mathrm{no}+1)}[a_{\mathrm{no}}{\mathrm{\&pi;}}_{\mathrm{no}}\left(\cos \mathrm{\&theta;}\right)+b_{\mathrm{no}}{\mathrm{\&tau;}}_{\mathrm{no}}\left(\cos \mathrm{\&theta;}\right)]$

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

Wherein, a _n and b _n are Mie scattering coefficients, and the Mie scattering coefficient is a function of the ratio parameter α (α=2πr/λ) of the single particle size r to the laser wavelength λ.

As shown in Figure 2 and Figure 6, the laser is emitted by the pulsed laser emitting subsystem. The laser pulse propagates in the atmosphere and interacts with aerosols of different components. The backscattered light signal of aerosol information is received by the optical signal receiving subsystem. Due to the different scattering characteristics of the laser on aerosols with different radii, the collected backscattered light signals are also different. Physical properties of the sol.

The main condition for the formation of atmospheric waveguide in the ocean is the relative humidity of the atmosphere. The relative humidity of the ocean atmosphere affects the physical characteristics of the atmospheric environment aerosol in the evaporation waveguide. Aerosol particles with different physical characteristics have different light scattering characteristics for laser light. The technical atmospheric waveguide detection method is established by using the relationship between the atmospheric refractive index and relative humidity, and relative humidity and aerosol.

与入射光方向之间的散射角为θ，入射光的电矢量相对于散射面的夹角为

The laser scattering characteristics of aerosol particles with different physical characteristics are different. According to the Mie scattering theory, as shown in Figure 3, the refractive index of a particle with a radius R relative to the surrounding medium is expressed as m=m ₁ +jm ₂ by a complex number, the refractive index of the medium is n, and the imaginary part is not equal to zero, indicating that the particle has absorb. Taking the center of the particle as the origin O of the coordinates, linearly polarized light with a wavelength of λ and an intensity of I ₀ in vacuum is incident on the particle along the z-axis, and the scattered light

The scattering angle between the direction of the incident light and the incident light is θ, and the angle between the electric vector of the incident light and the scattering surface is

If the incident light is natural light with intensity I ₀ , then the scattered light intensity at point P at a distance R from the atmospheric center O is:

${\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; sca</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\frac{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; 8</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

为：Angle-dependent scattered light intensity in formula (1)

for:

In formula (2), I ₁ and I ₂ represent the components of the scattering intensity function perpendicular to and parallel to the scattering plane, respectively, and S1 and S2 represent the amplitude function, and their infinite series form is:

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</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><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</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><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

In formulas (3) and (4), a _n and b _n are Mie scattering coefficients, which are functions of the ratio of the single particle size r to the light wavelength λ as the parameter α (α=2πr/λ). It can be seen that the size of aerosol particles and the laser wavelength jointly determine the scattering of individual particles, and further determine the scattering characteristics of particle groups.

The radius range of aerosol particles is generally not greater than 10 ² μm. For marine aerosols, the concentration is the highest at a radius of about 1-16 μm. During the simulation, the wavelength of the laser is set at 1.064 μm and 0.532 μm, the refractive index of the ocean aerosol particles is set at n=1.55, and the refractive index of the water in the outer layer of the aerosol is set at n=1.33.

According to the calculation formula of Mie scattering theory, when the incident light wavelength λ=1.064 μm, the particle radius is 1 μm, and the aerosol refractive index is respectively taken as n=1.55 and n=1.33, the scattering situation of a single particle is shown in Figure 4A and Figure 4B respectively Show. The abscissa is the scattering angle, the ordinate is the common logarithm of the scattering intensity, 'uprightness' indicates that the incident photoelectric vector is perpendicular to the scattering plane, and 'parallel' indicates that the incident photoelectric vector is parallel to the scattering plane. It can be seen from Figure 4A and Figure 4B that the scattered light is mainly concentrated in the forward direction, and when the scattering angle is around 180°, the scattered light intensity is significantly enhanced, that is, the backward scattering is significantly enhanced.

When the incident light wavelength λ=1.064 μm, the aerosol refractive index is n=1.55, and the particle radii are r=10 μm and 50 μm respectively, the scattering conditions of a single particle are shown in Figure 5A and Figure 5B respectively. When the radius of the bubble gradually increases, the intensity of scattered light increases accordingly, and the asymmetry of light intensity distribution gradually strengthens. The intensity of forward scattered light is much stronger than that of backward scattered light, especially around the scattering angle θ=0° The intensity of scattered light becomes sharper. However, as the bubble radius increases, the absolute value of the backscattering intensity increases gradually, especially around the scattering angle θ=180°. ° near the scattering angle has formed a relatively sharp peak, the larger the radius, the greater the peak intensity.

It can be seen from the simulation analysis that in the radius distribution range (0.1-100 μm) of the aerosol in the evaporative waveguide environment, the aerosol particles will generate a certain intensity of backscattered light signals under the incidence of laser light, and as the particle radius increases, the scattering The intensity of the light is enhanced accordingly, and the peak signal of the backscattered light with a scattering angle of 180° is more prominent, which provides favorable conditions for using the backscattered light signal of the aerosol to detect the atmospheric waveguide.

Preferably, the above-mentioned step 14 is specifically: according to the distribution characteristics of the laser detection backscattered light signal generated after the laser irradiates aerosol particles with different radii in different temperature, humidity and pressure environments and the vertical refractive index gradient in the atmosphere is less than - At 157N/KM, the atmospheric waveguide is generated, and the characteristic parameters of the atmospheric waveguide can be obtained, wherein the characteristic parameters of the atmospheric waveguide include: the duration of the waveguide layer, the height of the waveguide layer, the horizontal extension range of the waveguide layer, and the probability of occurrence of the evaporation wave layer and the meteorological and hydrological conditions that produce the evaporative duct.

Specifically, according to the radar band atmospheric refractive index model, the influence of different atmospheric temperature, humidity, and pressure environments on the atmospheric refractive index is analyzed.

Atmospheric vertical refractive index change is a common criterion for detecting atmospheric ducts. Atmospheric environments with different humidity, temperature, and pressure determine the atmospheric refractive index of radio waves. In the troposphere of the atmosphere, the relationship between the refractive index N (radio refractive index) of the atmosphere and temperature, air pressure, and water pressure is:

$\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; A</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; be</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

In formula (5), P _a is air pressure (hPa); e is water pressure (hPa); T is air temperature (K); A and B are constants determined by experiments. From formula (1), it is known that the atmospheric refractive index N changes with changes in atmospheric temperature, air pressure, and water pressure. In the marine atmospheric environment where the vertical height is below 50m and the evaporation waveguide is produced, the changes of atmospheric temperature T and atmospheric pressure _Pa are relatively insignificant, and the vertical distribution of the atmospheric refractive index mainly changes with the relative humidity in the air, and the atmospheric refractive index The index N mainly depends on the change of the water pressure e. When the saturated water vapor pressure near the ocean surface rises to a certain height, it suddenly drops sharply, meeting the condition that the vertical atmospheric refractive index gradient is less than -157N/km, that is, the ocean-atmospheric duct is formed.

Specifically, a model of the changes in the physical characteristics of aerosols caused by the atmospheric waveguide environment with different humidity, temperature, and pressure is established, and the backscattering characteristics of such aerosols are obtained by laser detection through experiments, and the laser echo signal and atmospheric pressure are further obtained. relationship to the waveguide environment.

The physical properties of aerosols in the lower ocean air are mainly affected by relative humidity. When water vapor evaporated from the ocean condenses on the aerosol particles, the physical properties of the aerosol particles change dramatically. When the relative humidity is f, the ratio of the radius r(f) of wet aerosol particles to the radius r of dry aerosol particles can be calculated by the following empirical formula:

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

where μ is a constant coefficient. For marine atmospheres, μ = 3.9. For a polluted atmosphere, μ = 4.4. If the relative humidity f is known, the ratio P of the radius of the wet aerosol particle to the radius of the dry aerosol particle can be obtained from formula (6). Changes in atmospheric relative humidity directly affect the physical properties of the aerosol, and further affect the laser backscattering properties of the aerosol. Since the formation mechanism of the ocean-atmosphere waveguide is that the saturated water vapor pressure near the ocean surface rises to a certain height and then suddenly decreases sharply, which will inevitably lead to a very obvious change in the radius of the aerosol in the atmosphere. The change in the laser backscattering characteristics of the aerosol can be Inversion is performed on changes in atmospheric environment characteristics to determine whether atmospheric ducts are generated.

Furthermore, according to the laser backscattering characteristics of aerosols in different humidity, temperature, and pressure environments of the ocean atmosphere, the ocean atmosphere waveguide laser detection model is completed through ocean field detection and system correction, and the characteristic parameters of the atmosphere waveguide are further obtained.

The characteristic parameters of the atmospheric duct include: the duration of the duct layer, the height of the duct layer, the horizontal extension of the duct layer, the probability of the occurrence of the evaporation duct, and the meteorological and hydrological conditions that produce the evaporation duct on the sea surface. These parameters are related to the distribution characteristics of aerosols. The method of laser detection can be used to detect the marine atmospheric environment in real time. Through the characteristics of laser echo signals, the distribution characteristics of aerosols in the marine atmosphere can be obtained. Combined with the results of marine field detection, the laser detection atmospheric waveguide model can be corrected, and the atmospheric waveguide lidar development support.

In the above embodiment of the present invention, the wavelength of the laser is preferably 1.064 μm, the radius of the aerosol particle ranges from 0.1 μm to 100 μm, the refractive index of the aerosol particle is 1.55, and the outer cladding water of the aerosol is The refractive index is 1.33.

As shown in Figure 6, it is the system for detecting the atmospheric waveguide environment of the present invention, including:

The detector is used to emit laser light into the simulated atmospheric environment, and obtain the laser detection backscattered light signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment;

A processor for analyzing the scattered light signal after the laser detection, to obtain the backscattering characteristics of the aerosol particles with different radii detected by the laser; and according to the backscattering characteristics of the aerosol particles in different temperature, humidity and pressure environments characteristics and changes in atmospheric refractive index to obtain the characteristic parameters of the atmospheric waveguide.

Wherein, as shown in Figure 6 and Figure 7, the detection machine includes:

The laser emitting subsystem is used to emit laser light into the simulated atmospheric environment;

The optical signal receiving subsystem is used to obtain the laser detection backscattered optical signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment;

Wherein, the laser emission subsystem includes:

A pulsed laser for generating laser light with a pulse energy of 20mJ, a pulse width of 10ns, and a wavelength of 1.064μm; and

A transmitting antenna for transmitting the laser light generated by the pulsed laser into a simulated atmospheric environment;

Wherein, the optical signal receiving subsystem includes:

The receiving antenna is used to receive the laser detection backscattered light signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment;

a detector, configured to detect the backscattered light signal of the laser detection, and output a high-speed transient weak light signal;

A broadband low-noise amplifier, used to amplify the high-speed transient weak optical signal;

The avalanche photodiode bias booster is used to receive the high-speed transient weak light signal output by the detector and output it to the processor.

输入电流噪声小于

Wherein, the transconductance gain of the broadband low noise amplifier is above 1.5GHz, and the input voltage noise is less than

Input current noise is less than

Wherein, the avalanche photodiode bias booster further includes: an avalanche photodiode, a digital temperature chip, a digital/analog converter, and a microprocessor, wherein the microprocessor reads out the current value through the digital temperature chip Describe the surface temperature value of the avalanche photodiode APD, use the temperature-bias compensation curve under the fixed gain of the APD, obtain the target bias voltage V _goal of the APD at the current temperature, and adjust the current bias voltage V _control of the APD to the target bias voltage through the digital/analog converter Press V _goal .

Wherein, the response time of the avalanche photodiode is 450ps, and the noise current is

Wherein, the optical signal receiving subsystem also has a shielding device made of weak magnetic material.

Wherein, the weak magnetic material is metal aluminum with a thickness of 1.3 mm.

The following is a detailed description of the detection experiments of aerosols with different particle size distributions using laser detectors.

(1) Parameters of the lidar prototype.

As shown in Figure 6, the detector mainly includes a pulsed laser emitting subsystem and an optical signal receiving subsystem. The main function of the laser emitting subsystem is to collimate and expand the original beam emitted by the laser to improve the beam quality. The optical signal receiving subsystem is composed of a receiving optical system, a detector, a broadband low-noise amplifier, an avalanche photodiode bias boost system, and a low-ripple power supply system. The main function is to receive laser detection backscattered light carrying aerosol information Signal. The parameters of the prototype are: semiconductor pumped YAG pulse laser pulse energy P=20mJ, pulse width T=10ns, laser wavelength λ=1.064μm, laser emission aperture 25mm, receiving aperture 100mm, echo sampling frequency 800M, detection accuracy 0.1875m , The detection range is 2.2V.

(2) The laser radar detector also has the following characteristics:

(1) The weak magnetic material aluminum is selected as the shielding material of the optical signal receiving subsystem. The magnetic flux density B of this material has a linear relationship with the magnetic field strength H, and μ _r always remains constant in any frequency environment, which can be easily obtained by looking up the table. When the interference frequency is 100KHz to 1GHz, if the shielding layer is required The absorption loss is greater than 40dB, and the thickness of metal aluminum, the weak magnetic material, is at least 1.28mm. Because high-power lasers working in pulse mode generally use the instantaneous discharge of several high-voltage capacitors to provide energy for the pump source, the instantaneous current absorbed by the laser at the moment of light emission can be as high as 70A, and the duration is as short as nanoseconds. High current will generate strong electromagnetic radiation around the laser, laser power box and power line, causing strong interference to the receiver and test equipment. When designing the detector, choose to use metal aluminum with a thickness of 1.3mm as the shielding material.

(2) Select the low-noise optimization technology of broadband high-gain transconductance amplifier, which has the advantages of no sampling resistor, low noise, high sensitivity and wide bandwidth performance, and is convenient for receiving and processing optical signals. Since the laser backscatter of the far-field target is very weak, a detector with higher gain and lower noise is required. The output of the APD is a weak current signal in the order of μA. For its current-voltage conversion (I-V), there are mainly two ways to use the sampling resistor for I-V conversion and the transconductance amplifier to complete the I-V conversion. However, since the sum of the junction capacitance of the APD and the stray capacitance caused by wiring together with the sampling resistor will form a low-pass filter, the bandwidth performance cannot meet the requirements, and the sampling resistor will introduce additional noise, which is not conducive to the low noise index of the system . When the prototype was developed, a high-performance OP operational amplifier was chosen to form a transconductance amplifier to complete the I-V conversion task of the output signal of the avalanche photodiode (as shown in Figure 8). R1 and C1 are used to reduce the input bias current caused by the operational amplifier. DC and AC errors. Under certain conditions, for the transconductance amplifier shown in the figure, the output voltage and input current have the following relationship:

V _o ＝-I _s ·R _F (7)

Where V _o is the output voltage of the transconductance amplifier; I _s is the input current; R _F is the feedback resistance.

输入电流噪声小于

的较高增益带宽积的运算放大器，结合激光探测在不同大气环境下测试的需要，选取低噪声的FET输入型可调运算放大器芯片，型号为OPA657。但是放大器外置线性直流供电会产生噪声，这些被跨导放大倍数在10³V/A数量级放大后输出噪声能够被轻易地放大到mV数量级。设计时，选择放大器的旁路电路滤掉噪声，改用锂电池供电并缩短电源线，进一步降低系统噪声。(3) Select the optimization technique of high-gain wide-bandwidth input adjustable operational amplifier. Regarding the selection of the operational amplifier, considering that the bias current of the operational amplifier chip should be much smaller than the minimum signal current detected, the input bias current should be less than 10pA as much as possible; while satisfying the wide bandwidth, the amplifier should be of the order of 10 ³ The transconductance gain must be selected above 1.5GHz, and the input voltage noise is less than

Input current noise is less than

The high gain-bandwidth product operational amplifier, combined with the needs of laser detection in different atmospheric environments, selects a low-noise FET input adjustable operational amplifier chip, the model is OPA657. However, the external linear DC power supply of the amplifier will generate noise, and the output noise can be easily amplified to the order of mV after the transconductance amplification factor is amplified on the order of 10 ³ V/A. When designing, select the bypass circuit of the amplifier to filter out the noise, switch to a lithium battery for power supply and shorten the power line to further reduce the system noise.

(4) APD adaptive numerical control bias boost technology. The avalanche photodiode is very sensitive to temperature, and a rise in temperature will greatly change the multiplication factor of the avalanche photodiode, which will affect the detection results. The high-precision and high-stability APD adaptive temperature control boost system can track and compensate the APD gain error caused by temperature changes. The block diagram of the boost system is shown in Figure 9. Compared with the traditional temperature control circuit based on discrete components, this circuit has the advantages of simple circuit, low noise, high precision, and little influence from external and installation factors, which better guarantees the performance index of the system. The working process is as follows: the digital temperature chip is installed close to the APD, and under the control of the microprocessor, the current APD surface temperature value T is accurately read out. The microprocessor uses the internally programmed temperature-bias compensation curve of the APD under fixed gain to obtain the target bias voltage V _goal of the APD at the current temperature, and the processor adjusts the current bias voltage V _control of the APD through the D/A converter to The target bias voltage V _goal , the adjustment process is monitored by an A/D converter. The software workflow of the microprocessor is shown in Figure 10.

(3) Experimental process.

In the corridor of the experimental building (90 meters long), simulate different temperature and humidity atmospheric environments, use the laser emitting and receiving system to obtain the backscattering echo signals of the laser on the aerosols with different particle radii, and further analyze the characteristics of the echo signals. Describe the characteristics and advantages of the method of laser detection of atmospheric ducts. The schematic diagram of the experiment is shown in Figure 11.

Experiment 1. The ambient air temperature is 15.6C and the relative humidity is 55.6%. Use an ordinary humidifier to generate aerosol particles with a radius of 1 μm to 10 μm to simulate an atmospheric environment similar to smoke and water clouds. The self-made laser radar prototype was used to detect the water atomized particles with a radius of 1 μm to 10 μm produced by the humidifier, and the echo signal after collecting 10 sets of data mean and filtering was shown in Figure 12A, which was the echo signal when no aerosol was added to the atmosphere; Figure 12B is the echo signal at 20 meters with a relative humidity of 82.3%; Figure 12C is the echo signal at 45 meters with a relative humidity of 85.6%.

Experiment 2. Environment The atmospheric temperature is 18.6°C and the relative humidity is 52.5%. Using ordinary steam irons, aerosol particles with a radius of 0.1 μm to 10 μm are produced, and the apparent diffusion range is 0 to 3 meters, simulating an atmospheric environment similar to smoke, dust, fog, and haze at different temperatures and humidity. Microparticles with a radius of 0.1 μm to 10 μm produced by steam irons were detected using a self-made lidar prototype. Figure 13A shows the echo signal after collecting 10 groups of data mean values and filtering the echo signal when there is no aerosol in the atmosphere; Figure 13B shows when the steam iron is moved from 25 to 35 meters, the temperature is 22.2 ° C, and the relative humidity is 87.5 % echo signal; Fig. 13C is the echo signal when the steam iron is moved from 25 to 35 meters, the temperature is 23.1°C and the relative humidity is 95.2%.

Experiment 3, the ambient air temperature is 21.6°C and the relative humidity is 62.5%. Using an ordinary sprayer, particles with a radius of 10 to 100 microns are produced, and the apparent diffusion range is 0 to 1 meter, simulating an atmospheric environment similar to fog and spray at different temperatures and humidity. The prototype is used to detect the particles (with a radius of 10 μm to 100 μm) produced by the nebulizer at different temperatures, and the obvious diffusion range is 0.5 to 1 meter. The echo signal after collecting 10 sets of data and filtering the mean value is shown in Figure 14A, which shows that no aerosol has been added to the atmosphere 14B, respectively at 20 and 30 meters, the relative humidity is respectively 95.6% and 90.2%, and the temperature is 24.5 ℃, and the spray range is the echo signal of 0.5 meters; Fig. 14C is respectively at 30 and 65 meters, and the relative humidity is 100%, the temperature is 25.0 ℃, and the echo signal of the spray range is 0.5 meters; Figure 14D shows that the spray range is 0.5 meters at the 25 places where the spray range is 1 meter and 45 meters, and Echo signal at a relative humidity of 95.3% and a temperature of 25.2°C.

(4) Analysis of experimental results.

This experiment has good controllability and strong operability, and the atmospheric parameters and particle size distribution can be set according to the needs, which is convenient for comparative analysis with theoretical research. It is obtained through experiments that the backscattering degree of laser light to particles with different radii is also different under different temperature and humidity conditions. Under the same atmospheric conditions, the particle radius changes from 0.1 μm to 100 μm, and its backscattering signal intensity gradually increases. The larger the particle density range, the greater the signal intensity. The same particle has the same radius, and the greater the humidity changes, the greater the backscattering The greater the intensity, it shows that the method of using laser to detect atmospheric waveguide is feasible, with obvious characteristics and advantages.

(1) High detection sensitivity. The experiment uses a laser with a wavelength of 1.06 μm to detect aerosol particles with a radius of 0.1 μm to 100 μm. It can be seen from Experiment 1 that the density of water atomized particles with a radius of 1 μm to 10 μm produced by the humidifier is much smaller than that of the evaporated waveguide aerosol. When the laser is used to detect the particle group at 20 meters, the backscattered signal Strong, when the particle swarm moves to 45m, it can also collect obvious backscattering signals. In the third experiment, when the spray range increased from 0.5m to 1m, the echo signal also increased several times, and the echo signal of particles could still be collected at 65 meters. Experiments have shown that since the wavelength of the laser is equivalent to the scale of atmospheric aerosols such as smoke, dust, and water vapor, and the pulse width of the laser can reach ns level, and the detection sensitivity of the photodetector is high, the atmospheric waveguide using laser technology has high sensitivity.

(2) High temporal and spatial resolution. During the second experiment, as the range of particles produced by the steam iron changed slightly, the peak range of the backscattered signal changed immediately. When the steam iron was moved from 25 meters to 35 meters, due to the aerosol particles in the air Without timely diffusion, the peak range of the echo signal is also wide. Experiments show that this method adopts innovative technologies such as high-speed transient optical signal reception, high-speed data acquisition, and adaptive temperature control of avalanche photodiodes. The analog/digital sampling frequency is 800MHz, the sampling accuracy is 0.1875m, and it has high temporal and spatial resolution.

Starting from the relationship between the change of atmospheric refractive index and relative humidity, and the relationship between relative humidity and aerosol physical properties, the theoretical connection between laser backscattering and the conditions for generating evaporation waveguides was established, and the atmospheric environment for generating evaporation waveguides was simulated through experiments. The backscattering characteristics of different characteristic aerosols were compared and analyzed. The study proves that from the perspective of atmospheric relative humidity, it is feasible to study the new method of using laser technology to detect evaporation waveguide, which has high detection sensitivity, high temporal and spatial resolution, strong anti-interference, strong confidentiality, good real-time performance, and reliable With the advantages of working around the clock, it can better meet the military needs of real-time forecasting of the atmospheric duct environment under complex battlefield conditions.

Embodiments of the present invention also provide a detection machine, comprising:

The laser emitting subsystem is used to emit laser light into the simulated atmospheric environment;

The optical signal receiving subsystem is used to obtain the laser detection backscattered optical signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment;

Wherein, the laser emission subsystem includes:

A pulsed laser for generating laser light with a pulse energy of 20mJ, a pulse width of 10ns, and a wavelength of 1.064μm; and

A transmitting antenna for transmitting the laser light generated by the pulsed laser into a simulated atmospheric environment;

Wherein, the optical signal receiving subsystem includes:

The receiving antenna is used to receive the laser detection backscattered light signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment;

a detector, configured to detect the backscattered light signal of the laser detection, and output a high-speed transient weak light signal;

A broadband low-noise amplifier, used to amplify the high-speed transient weak optical signal;

The avalanche photodiode bias booster is used to receive the high-speed transient weak light signal output by the detector and output it to a processor connected to the detector.

Preferably, the processor follows the formula $I_{\mathrm{sca}}=I_0\frac{{\mathrm{\&lambda;}}^2}{{8\mathrm{\&pi;}}^2{R}^2}I(\mathrm{\&theta;},\mathrm{\&phi;})$ to the said

为与角度相关的散射光强度，其中，其中，I₁、I₂分别表示垂直和平行于散射平面的散射强度函数分量，S₁、S₂表示幅值函数，其无穷级数形式为：The scattered light signal after laser detection is analyzed, and the backscattering characteristics of aerosols with different radii in laser detection are obtained: the backscattered light signal generated by aerosol particles under the incidence of laser light increases with the increase of the radius of the aerosol particle The intensity of scattered light is correspondingly enhanced; where, I ₀ is the intensity of incident light, I _sca is the scattered light intensity of point P at a distance R from the center of the atmosphere O,

is the angle-dependent scattered light intensity, where, Among them, I ₁ and I ₂ represent the components of the scattering intensity function perpendicular to and parallel to the scattering plane, respectively, and S ₁ and S ₂ represent the amplitude function, whose infinite series form is:

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

Wherein, a _n and b _n are Mie scattering coefficients, and the Mie scattering coefficient is a function of the ratio parameter α (α=2πr/λ) of the single particle size r to the laser wavelength λ.

The present invention is based on the light scattering characteristics of aerosols in atmospheric environments such as different temperatures, humidity, and air pressures, and the relevant principles of changes in the atmospheric refractive index of radio waves, and establishes the characteristics of laser backscattered echo signals and the physical elements of the atmosphere when the phenomenon of atmospheric waveguide occurs. According to the relationship model of the laser echo characteristic change, the relevant parameters of the waveguide environment are inverted, and whether the atmospheric waveguide phenomenon occurs is judged in real time, providing atmospheric environment data support for military activities such as microwave atmospheric waveguide over-the-horizon radar over-the-horizon detection.

The atmospheric waveguide laser detection method of the present invention has the following technical effects:

(1) High detection sensitivity. The invention is based on the Mie backscattering theory, adopts a laser of about 1 micron, and detects in all directions and in real time. Since the wavelength of the laser is equivalent to the scale of atmospheric aerosols such as smoke, dust, and water vapor, and the pulse width of the laser can reach ns level, and the detection sensitivity of the photodetector is high, the light intensity of the atmospheric scattered light contained in the laser atmospheric echo signal, Information such as frequency, phase, and polarization can detect a variety of atmospheric physical elements, so laser detection of atmospheric particles has high detection sensitivity.

(2) High temporal and spatial resolution. The present invention adopts SAE500VS3 type low-noise avalanche photodiode (response time 450ps, noise current is about ) to receive high-speed transient weak light signals; select a high-speed data acquisition module, the analog/digital sampling frequency is 800MHz, and the sampling accuracy is 0.1875m (3.0×108/800×106/2). Using a laser with an energy of 20mJ can effectively detect the evaporation waveguide environment with a level of 2Km and a height of 0.2Km.

(3) Confidentiality is good. In the complex electromagnetic environment of the battlefield, using radar waves to detect atmospheric ducts is easy to expose targets, and is vulnerable to interference and attacks. Due to the unidirectionality of laser transmission (divergence angle can be controlled below 1mrad) and good confidentiality, it is not easy to be intercepted by laser radar to detect atmospheric waveguide, and it has high concealment. On the battlefield, the radar does not need to be turned on, and the waveguide environmental parameters can be obtained by means of laser detection, which provides data reference for radar communication and over-the-horizon detection.

(4) Strong anti-interference performance. The laser working frequency band adopted is different from the working frequency band of radar, communication equipment, etc. There is no mutual interference between the equipment, and it is not subject to external electromagnetic interference, and it is also effective in complex electromagnetic environments.

(5) Strong universality and practicability. Due to the short wavelength of the laser, the size of the optical transceiver antenna is much smaller than that of the microwave communication antenna under the same function. The laser detection atmospheric waveguide has the advantages of small power consumption, small size, light weight, and low cost. It is easy to transform technological achievements and is practical. Strong.

The above description is a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (13)

1. A method for detecting atmospheric duct environment, characterized in that, comprising: Launch laser into simulated atmospheric environment; Obtaining the laser detection backscattered light signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment; Analyzing the scattered light signal after the laser detection to obtain the backscattering characteristics of the laser detection of the aerosol particles with different radii; According to the backscattering characteristics of aerosol particles in different temperature, humidity and pressure environments and the change of atmospheric refractive index, the characteristic parameters of the atmospheric waveguide are obtained. 2. The method according to claim 1, wherein the scattered light signal is analyzed after the laser detection, and the step of obtaining the backscattering characteristics of the laser detection of the aerosol particles with different radii is specifically: by the following formula $I_{\mathrm{sca}}=I_0\frac{{\mathrm{\&lambda;}}^2}{{8\mathrm{\&pi;}}^2{R}^2}I(\mathrm{\&theta;},\mathrm{\&phi;})$ The scattered light signal after the laser detection is analyzed, and the backscattering characteristics of the laser detection of the aerosols with different radii are obtained: aerosol particles generate backscattered light signals under the incident laser Large, the intensity of the backscattered light increases accordingly; Among them, I ₀ is the intensity of incident light, λ is the laser wavelength, I _sca is the scattered light intensity at point P at a distance R from the center of the atmosphere O,

is the angle-dependent scattered light intensity, where,

Among them, I ₁ and I ₂ represent the components of the scattering intensity function perpendicular to and parallel to the scattering plane, respectively, and S ₁ and S ₂ represent the amplitude function, whose infinite series form is: $S_1\left(\mathrm{\&theta;}\right)=\underset{\mathrm{no}=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{2\mathrm{no}+1}{\mathrm{no}(\mathrm{no}+1)}[a_{\mathrm{no}}{\mathrm{\&pi;}}_{\mathrm{no}}\left(\cos \mathrm{\&theta;}\right)+b_{\mathrm{no}}{\mathrm{\&tau;}}_{\mathrm{no}}\left(\cos \mathrm{\&theta;}\right)]$ ${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$ Wherein, a _n and b _n are Mie scattering coefficients, and the Mie scattering coefficient is a function of the ratio parameter α (α=2πr/λ) of the single particle size r to the laser wavelength λ. 3. The method according to claim 2, characterized in that, according to the backscattering characteristics of the aerosol particles in different temperature, humidity and pressure environments and the variation of the atmospheric refractive index, the step of obtaining the characteristic parameters of the atmospheric waveguide is specifically: According to the distribution characteristics of laser detection backscattered light signals generated by laser irradiation on aerosol particles with different radii in different temperature, humidity and pressure environments and when the vertical refractive index gradient of the atmosphere is less than -157N/KM, the characteristics of the atmospheric waveguide are obtained Parameters, wherein the atmospheric waveguide characteristic parameters include: the duration of the waveguide layer, the height of the waveguide layer, the horizontal extension range of the waveguide layer, the probability of the occurrence of the evaporation wave layer, and the meteorological and hydrological conditions for generating the evaporation waveguide. 4. The method according to any one of claims 1-3, characterized in that, the wavelength of the laser is 1.064 μm, the radius of the aerosol particles ranges from 0.1 μm to 100 μm, and the aerosol particles refract The index of refraction is 1.55, and the refractive index of water in the outer envelope of the aerosol is 1.33. 5. A system for detecting an atmospheric duct environment, comprising: The detector is used to emit laser light into the simulated atmospheric environment, and obtain the laser detection backscattered light signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment; A processor for analyzing the scattered light signal after the laser detection, to obtain the backscattering characteristics of the aerosol particles with different radii detected by the laser; and according to the backscattering characteristics of the aerosol particles in different temperature, humidity and pressure environments characteristics and changes in atmospheric refractive index to obtain the characteristic parameters of the atmospheric waveguide. 6. The system according to claim 5, wherein the detection machine comprises: The laser emitting subsystem is used to emit laser light into the simulated atmospheric environment; The optical signal receiving subsystem is used to obtain the laser detection backscattered optical signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment; Wherein, the laser emission subsystem includes: A pulsed laser for generating laser light with a pulse energy of 20mJ, a pulse width of 10ns, and a wavelength of 1.064μm; and A transmitting antenna for transmitting the laser light generated by the pulsed laser into a simulated atmospheric environment; Wherein, the optical signal receiving subsystem includes: The receiving antenna is used to receive the laser detection backscattered light signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment; a detector, configured to detect the backscattered light signal of the laser detection, and output a high-speed transient weak light signal; A broadband low-noise amplifier, used to amplify the high-speed transient weak optical signal; The avalanche photodiode bias booster is used to receive the high-speed transient weak light signal output by the detector and output it to the processor. 7. The system according to claim 6, wherein the transconductance gain of the broadband low noise amplifier is above 1.5GHz, and the input voltage noise is less than

Input current noise is less than

8. The system according to claim 6, wherein the avalanche photodiode bias booster comprises: an avalanche photodiode, a digital temperature chip, a digital/analog converter and a microprocessor, wherein the microprocessor The processor reads the current surface temperature value of the avalanche photodiode APD through the digital temperature chip, uses the temperature-bias voltage compensation curve under the fixed gain of the APD, obtains the target bias voltage V _goal of the APD at the current temperature, and uses the digital/analog The converter adjusts the current bias voltage V _control of the APD to the target bias voltage V _goal . 9. The system according to claim 8, wherein the response time of the avalanche photodiode is 450 ps, and the noise current is

10. The system according to claim 6, wherein the optical signal receiving subsystem further has a shielding device made of a weak magnetic material. 11. The system according to claim 10, wherein the weak magnetic material is metal aluminum with a thickness of 1.3 mm. 12. The system according to claim 6, characterized in that, the processor uses the following formula $I_{\mathrm{sca}}=I_0\frac{{\mathrm{\&lambda;}}^2}{{8\mathrm{\&pi;}}^2{R}^2}I(\mathrm{\&theta;},\mathrm{\&phi;})$ The scattered light signal after the laser detection is analyzed, and the backscattering characteristics of the laser detection of the aerosols with different radii are obtained: aerosol particles generate backscattered light signals under the incident laser Large, the intensity of the backscattered light increases accordingly; Among them, I ₀ is the intensity of incident light, λ is the laser wavelength, I _sca is the scattered light intensity at point P at a distance R from the center of the atmosphere O,

is the angle-dependent scattered light intensity, where,

Among them, I ₁ and I ₂ represent the components of the scattering intensity function perpendicular to and parallel to the scattering plane, respectively, and S ₁ and S ₂ represent the amplitude function, whose infinite series form is: $S_1\left(\mathrm{\&theta;}\right)=\underset{\mathrm{no}=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{2\mathrm{no}+1}{\mathrm{no}(\mathrm{no}+1)}[a_{\mathrm{no}}{\mathrm{\&pi;}}_{\mathrm{no}}\left(\cos \mathrm{\&theta;}\right)+b_{\mathrm{no}}{\mathrm{\&tau;}}_{\mathrm{no}}\left(\cos \mathrm{\&theta;}\right)]$ ${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$ Wherein, a _n and b _n are Mie scattering coefficients, and the Mie scattering coefficient is a function of the ratio parameter α (α=2πr/λ) of the single particle size r to the laser wavelength λ. 13. A detector, characterized in that it comprises: The laser emitting subsystem is used to emit laser light into the simulated atmospheric environment; The optical signal receiving subsystem is used to obtain the laser detection backscattered optical signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment; Wherein, the laser emission subsystem includes: A pulsed laser for generating laser light with a pulse energy of 20mJ, a pulse width of 10ns, and a wavelength of 1.064μm; and A transmitting antenna for transmitting the laser light generated by the pulsed laser into a simulated atmospheric environment; Wherein, the optical signal receiving subsystem includes: The receiving antenna is used to receive the laser detection backscattered light signal generated after the laser irradiates the aerosol particles with different radii in the simulated atmospheric environment; a detector, configured to detect the backscattered light signal of the laser detection, and output a high-speed transient weak light signal; A broadband low-noise amplifier, used to amplify the high-speed transient weak optical signal; The avalanche photodiode bias booster is used to receive the high-speed transient weak light signal output by the detector and output it to a processor connected to the detector.

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