CN104007088B - The measuring method of back scattering laser radar geometric factor - Google Patents

Abstract

The invention discloses a kind of measuring method of back scattering laser radar geometric factor.After it uses CCD camera to record gasoloid backscattering coefficient, first gasoloid backscattering coefficient is substituted into Backscattering lidar equation <maths num=" 0001 " > in </maths>, P (z) in equation is the atmospheric backscatter echoed signal at laser radar receiving range z place, C is the constant that laser radar system comprises energy, and η (z) is geometric factor, β ₁(z), β ₂z () is respectively gasoloid backscattering coefficient and the atmospheric molecule backscattering coefficient at distance z place, α ₁(z), α ₂z () is respectively Aerosol Extinction and the atmospheric molecule extinction coefficient at distance z place, dz is height resolution, re-uses the geometric factor that process of iteration obtains back scattering laser radar.The accuracy of the geometric factor recorded is high and easily measure, and uses the signal of geometric factor to back scattering laser radar recorded to revise, greatly increases the precision of atmospheric sounding parameter and pollutant levels in zone of transition; Can be widely used in the detection of back scattering laser radar to closely section atmosphere pollution.

Description

The measuring method of back scattering laser radar geometric factor

Technical field

The present invention relates to a kind of measuring method of laser radar geometric factor, especially a kind of measuring method of back scattering laser radar geometric factor.

Background technology

Back scattering laser radar is a kind of powerful of pollutant in atmospheric sounding parameter, air, but because its emitter and receiving trap are at same position, result in and has the existence of blind area and zone of transition in closely section.So-called blind area is exactly the region that Airborne Lidar does not detect transmitted beam backscatter signal; So-called zone of transition is exactly the region that Airborne Lidar measures fractional transmission light beam backscatter signal.Conventional geometric factor η describes the integrated degree detecting transmitted beam backscatter signal, η=0 is called blind area, 0 < η < 1 is called zone of transition, and η=1 is complete reception area, is exactly complete reception area after zone of transition.Geometric factor is the function of laser radar system device hardware location, radiating laser beams angle and opening of the telescope, and is not easy to be accurately.The zone of transition distalmost end distance of general laser radar is about about 800 meters, which limits the application of back scattering laser radar in closely occasion, and the scope of the closely detection of section atmosphere pollution environmental protection and the special concern of institute of meteorological department just.

The method of existing measurement back scattering laser radar geometric factor is the night of a selection gasoloid horizontal homogeneous distribution, allows laser radar work in the horizontal direction, is measured the geometric factor of back scattering laser radar by Slope Method.Though this measuring method also can obtain the geometric factor of back scattering laser radar, but the restriction because being subject to weather conditions is had, and be difficult to the defect that utilizes the signal of geometric factor to back scattering laser radar to revise in real time, constrain the investigative range of back scattering laser radar.

For avoiding this difficult problem, the applicant has done some and has attempted and effort, as the method for a kind of side direction lidar measurement aerosol parameters based on CCD imaging technique that Chinese invention patent application CN103344611A announced on October 9th, 2013.Though the method avoids the impact of geometric factor in back scattering laser radar, it is made to be well suited for for detecting the atmospheric aerosol space distribution of surface layer; But, when it faces existing back scattering laser radar, still feel inadequate.

Summary of the invention

The technical problem to be solved in the present invention is the limitation overcoming above-mentioned various technical scheme, provides the measuring method of the easy Accurate Determining of a kind of geometric factor and the good back scattering laser radar geometric factor of practicality.

For solving technical matters of the present invention, the technical scheme adopted is: the measuring method of back scattering laser radar geometric factor comprises use CCD camera and records gasoloid backscattering coefficient, particularly,

First gasoloid backscattering coefficient is substituted into Backscattering lidar equation $P\left(z\right)=\mathrm{C\&eta;}\left(z\right)\frac{{\mathrm{\&beta;}}_1\left(z\right)+{\mathrm{\&beta;}}_2\left(z\right)}{z^2}\&times;\exp \{-2{\&Integral;}_0^z[{\mathrm{\&alpha;}}_1\left(z\right)+{\mathrm{\&alpha;}}_2\left(z\right)]\&times;\mathrm{dz}\}$ In, the P (z) in equation for the atmospheric backscatter echoed signal at laser radar receiving range z place, C be the constant that laser radar system comprises energy, η (z) is geometric factor, β ₁(z), β ₂z () is respectively gasoloid backscattering coefficient and the atmospheric molecule backscattering coefficient at distance z place, α ₁(z), α ₂z () is respectively Aerosol Extinction and the atmospheric molecule extinction coefficient at distance z place, dz is height resolution, re-uses the geometric factor that process of iteration obtains back scattering laser radar.

Further improvement as the measuring method of back scattering laser radar geometric factor:

Preferably, the step using process of iteration to obtain back scattering laser radar geometric factor is:

Step 1, the initial geometric factor of the back scattering laser radar of setting zone of transition is η ' (z)=1;

Step 2, substitutes into Backscattering lidar equation by the geometric factor of setting $P\left(z\right)=\mathrm{C\&eta;}\left(z\right)\frac{{\mathrm{\&beta;}}_1\left(z\right)+{\mathrm{\&beta;}}_2\left(z\right)}{z^2}\&times;\exp \{-2{\&Integral;}_0^z[{\mathrm{\&alpha;}}_1\left(z\right)+{\mathrm{\&alpha;}}_2\left(z\right)]\&times;\mathrm{dz}\}$ In, use Fernald method to obtain gasoloid backscattering coefficient β ' ₁(z);

Step 3, by the gasoloid backscattering coefficient β ' obtained ₁z () compares with using the gasoloid backscattering coefficient that records of CCD camera, draw ratio beta ' ₁(z)/β ₁(z);

Step 4, if ratio beta ' ₁(z)/β ₁(z) <0.98, then the geometric factor resetting the back scattering laser radar of zone of transition be last geometric factor be multiplied by ratio beta ' ₁(z)/β ₁after (z), repeat step 2 ~ 3, until ratio beta ' ₁(z)/β ₁z ()>=0.98, obtains the geometric factor of back scattering laser radar.

Preferably, the distance between CCD camera and transmitted beam is 5 ~ 200m; Be beneficial to the consistance of measurement effect.

Preferably, CCD camera is less than in the half-light subnumber that-20 degree are lower that 1 photon number/pixel, always subtended angle are greater than 60 degree, resolution angle is less than 0.03 degree/pixel; Be beneficial to the more accurate measurement effect of acquisition.

Preferably, the wavelength of back scattering laser radar is 532nm, pulse energy >=50mJ; Be easy to obtain accurate measurement effect.

Preferably, the process using CCD camera to record gasoloid backscattering coefficient is:

Step 1, first CCD side direction laser radar is operated in air compared with in the horizontal direction in non-uniform time section, the gasoloid of selected scattering angle to be 179 ~ 180 degree of places be reference point is all 1 than phase function value and atmospheric molecule than phase function value, record the gasoloid backscattering coefficient value in reference point again, and assert that this value is all equal with the gasoloid backscattering coefficient value at scattering angle place each in horizontal direction, afterwards

Step 1.1, substitutes into side direction laser radar equation formula with reference to the bias angle theta of the gasoloid backscattering coefficient value on point and gasoloid pixel more each than phase function value and CCD camera, angular breadth d θ, CCD camera together with the vertical range D of laser radar transmitted beam in, the signal intensity that the P (θ) in equation receives for respective pixel on direction, θ drift angle, P ₀for the power of laser radar transmitted beam, K is the optical transmittance of receiving system, and A is the useful area of optical system, T _t, T _rbe respectively the transmitance on laser vertical direction and tilted direction, β (θ) is gasoloid lateral scattering coefficient, and it is by β (θ)=β ₁(θ) f ₁(θ)+β ₂(θ) f ₂(θ) form, the β in formula ₁(θ) be gasoloid backscattering coefficient, β ₂(θ) be atmospheric molecule backscattering coefficient, f ₁(θ) for gasoloid is than phase function, f ₂(θ) for atmospheric molecule is than phase function, Inversion Calculation goes out gasoloid on reference point consecutive point than phase function value by the following method,

If reference point scattering angle is θ _c, gasoloid backscattering coefficient is β ₁(θ _c), the optical thickness of air is τ _c, get constant side direction laser radar signal β ' (θ) then with decay is defined as

${\mathrm{\&beta;}}^{\&prime;}\left(\mathrm{\&theta;}\right)=\frac{P\left(\mathrm{\&theta;}\right)}{C}$ ①，

The expression formula of the side direction laser radar signal in theory with decay is,

β′(θ)＝[β ₁(θ)f(θ) ₁+β ₂(θ)f ₂(θ)]exp-(Δτ+τ _c(1/cos(π-θ)-1/cos(π-θ _c))+Δτ/cos(π-θ))dθ

②，

Δ τ in formula is that scattering angle is from θ _cto the SEQUENCING VERTICAL optical thickness at θ place, from reference point, use numerical algorithm, fit equation is formula and 2. formula 1., and numerical value solves gasoloid on reference point consecutive point than phase function f ₁(θ _c+ d θ),

Step 1.2, using consecutive point as new reference point, chooses new consecutive point to the direction that scattering angle diminishes, and repeat step 1.1, the gasoloid that numerical solution makes new advances on consecutive point is than phase function f ₁(θ _c+ d θ), until the gasoloid of all selected scattering angle, than phase function value, obtains gasoloid than phase function f in acquisition investigative range ₁(θ) profile;

Step 2, first CCD side direction laser radar is operated in surface level on perpendicular direction, and assert that gasoloid in the horizontal direction that obtained by step 1 is than equal with in vertical direction of phase function value, the somewhere chosen again on detection height is as a reference point, record the gasoloid backscattering coefficient value on this aspect, afterwards

Step 2.1, substitutes into side direction laser radar equation formula with reference to the bias angle theta of the gasoloid backscattering coefficient value on point and gasoloid pixel more each than phase function value and CCD camera, angular breadth d θ, CCD camera together with the vertical range D of laser radar transmitted beam in, Inversion Calculation goes out the gasoloid backscattering coefficient value on reference point consecutive point by the following method,

If reference point scattering angle is θ _c, gasoloid backscattering coefficient is β ₁(θ _c), the optical thickness of air is τ _c, get constant side direction laser radar signal β ' (θ) then with decay is defined as

${\mathrm{\&beta;}}^{\&prime;}\left(\mathrm{\&theta;}\right)=\frac{P\left(\mathrm{\&theta;}\right)}{C}$ ①，

The expression formula of the side direction laser radar signal in theory with decay is,

β′(θ)＝[β ₁(θ)f(θ) ₁+β ₂(θ)f ₂(θ)]exp-(Δτ+τ _c(1/cos(π-θ)-1/cos(π-θ _c))+Δτ/cos(π-θ))dθ

②，

Δ τ in formula is that scattering angle is from θ _cto the SEQUENCING VERTICAL optical thickness at θ place, from reference point, use numerical algorithm, fit equation is formula and 2. formula 1., and numerical value solves the gasoloid backscattering coefficient β on reference point consecutive point ₁(θ _c+ d θ),

Step 2.2, using consecutive point as new reference point, successively hoist and lower both direction chooses new consecutive point, repeating step 2.1, numerical solution makes new advances the gasoloid backscattering coefficient β on consecutive point ₁(θ _c+ d θ), until obtain the gasoloid backscattering coefficient value in investigative range on all selected height, obtain gasoloid backscattering coefficient β ₁(θ) profile;

Step 3 is that gasoloid obtains the profile of gasoloid phase function than the definition of phase function by the gasoloid phase function on θ angle and the ratio of gasoloid backscattering coefficient.

Relative to the beneficial effect of prior art be:

The present invention is by the method for the side direction lidar measurement aerosol parameters based on CCD imaging technique, the gasoloid backscattering coefficient that recorded substitutes in Backscattering lidar equation, and the accuracy of the geometric factor of the back scattering laser radar using process of iteration to obtain is high and easily measure.The result that warp and prior art record is compared, and both registrations are almost completely the same, effectively demonstrate science of the present invention and correctness.

When the present invention measures back scattering laser radar geometric factor, do not need this exacting terms at night selecting the distribution of gasoloid horizontal homogeneous, so have more practicality.The signal of geometric factor to back scattering laser radar recorded is used to revise, greatly increase the precision of atmospheric sounding parameter and pollutant levels in zone of transition, widen the investigative range of back scattering laser radar in closely section, expand the application of back scattering laser radar, improve the cost performance of back scattering laser radar, make back scattering laser radar also can be widely used in detection to closely section atmosphere pollution.

Accompanying drawing explanation

Fig. 1 is the result comparison chart of the back scattering laser radar geometric factor using prior art and the present invention to measure respectively.

Embodiment

Below in conjunction with accompanying drawing, optimal way of the present invention is described in further detail.

See Fig. 1, the measuring method of back scattering laser radar geometric factor is as follows:

First,

Selected distance between CCD camera and transmitted beam is 5 ~ 200m;

CCD camera is less than in the half-light subnumber that-20 degree are lower that 1 photon number/pixel, always subtended angle are greater than 60 degree, resolution angle is less than 0.03 degree/pixel;

The wavelength of back scattering laser radar is 532nm, pulse energy >=50mJ.

Secondly,

Use CCD camera to record gasoloid backscattering coefficient, its process is:

Step 1, first CCD side direction laser radar is operated in air compared with in the horizontal direction in non-uniform time section, the gasoloid of selected scattering angle to be 180 (can be 179 ~ 180) degree place be reference point is all 1 than phase function value and atmospheric molecule than phase function value, record the gasoloid backscattering coefficient value in reference point again, and assert that this value is all equal with the gasoloid backscattering coefficient value at scattering angle place each in horizontal direction; Wherein, the gasoloid backscattering coefficient value recorded in reference point is use back scattering laser radar.Afterwards,

Step 1.1, substitutes into side direction laser radar equation formula with reference to the bias angle theta of the gasoloid backscattering coefficient value on point and gasoloid pixel more each than phase function value and CCD camera, angular breadth d θ, CCD camera together with the vertical range D of laser radar transmitted beam in, the signal intensity that the P (θ) in equation receives for respective pixel on direction, θ drift angle, P ₀for the power of laser radar transmitted beam, K is the optical transmittance of receiving system, and A is the useful area of optical system, T _t, T _rbe respectively the transmitance on laser vertical direction and tilted direction, β (θ) is gasoloid lateral scattering coefficient, and it is by β (θ)=β ₁(θ) f ₁(θ)+β ₂(θ) f ₂(θ) form, the β in formula ₁(θ) be gasoloid backscattering coefficient, β ₂(θ) be atmospheric molecule backscattering coefficient, f ₁(θ) for gasoloid is than phase function, f ₂(θ) for atmospheric molecule is than phase function, Inversion Calculation goes out gasoloid on reference point consecutive point than phase function value by the following method,

If reference point scattering angle is θ _c, gasoloid backscattering coefficient is β ₁(θ _c), the optical thickness of air is τ _c, get constant side direction laser radar signal β ' (θ) then with decay is defined as

${\mathrm{\&beta;}}^{\&prime;}\left(\mathrm{\&theta;}\right)=\frac{P\left(\mathrm{\&theta;}\right)}{C}$ ①，

The expression formula of the side direction laser radar signal in theory with decay is,

β′(θ)＝[β ₁(θ)f(θ) ₁+β ₂(θ)f ₂(θ)]exp-(Δτ+τ _c(1/cos(π-θ)-1/cos(π-θ _c))+Δτ/cos(π-θ))dθ

②，

Δ τ in formula is that scattering angle is from θ _cto the SEQUENCING VERTICAL optical thickness at θ place, from reference point, use numerical algorithm, fit equation is formula and 2. formula 1., and numerical value solves gasoloid on reference point consecutive point than phase function f ₁(θ _c+ d θ),

Step 1.2, using consecutive point as new reference point, chooses new consecutive point to the direction that scattering angle diminishes, and repeat step 1.1, the gasoloid that numerical solution makes new advances on consecutive point is than phase function f ₁(θ _c+ d θ), in horizontal direction, the number of each consecutive point elects 3000 as, until the gasoloid of all selected scattering angle, than phase function value, obtains gasoloid than phase function f in acquisition investigative range ₁(θ) profile;

Step 2, first CCD side direction laser radar is operated in surface level on perpendicular direction, and assert that gasoloid in the horizontal direction that obtained by step 1 is than equal with in vertical direction of phase function value, the somewhere chosen again on detection height is as a reference point, records the gasoloid backscattering coefficient value on this aspect; Wherein, the gasoloid backscattering coefficient value recorded in reference point is use back scattering laser radar.Afterwards,

Step 2.1, substitutes into side direction laser radar equation formula with reference to the bias angle theta of the gasoloid backscattering coefficient value on point and gasoloid pixel more each than phase function value and CCD camera, angular breadth d θ, CCD camera together with the vertical range D of laser radar transmitted beam in, Inversion Calculation goes out the gasoloid backscattering coefficient value on reference point consecutive point by the following method,

If reference point scattering angle is θ _c, gasoloid backscattering coefficient is β ₁(θ _c), the optical thickness of air is τ _c, get constant side direction laser radar signal β ' (θ) then with decay is defined as

${\mathrm{\&beta;}}^{\&prime;}\left(\mathrm{\&theta;}\right)=\frac{P\left(\mathrm{\&theta;}\right)}{C}$ ①，

The expression formula of the side direction laser radar signal in theory with decay is,

β′(θ)＝[β ₁(θ)f(θ) ₁+β ₂(θ)f ₂(θ)]exp-(Δτ+τ _c(1/cos(π-θ)-1/cos(π-θ _c))+Δτ/cos(π-θ))dθ

②，

Δ τ in formula is that scattering angle is from θ _cto the SEQUENCING VERTICAL optical thickness at θ place, from reference point, use numerical algorithm, fit equation is formula and 2. formula 1., and numerical value solves the gasoloid backscattering coefficient β on reference point consecutive point ₁(θ _c+ d θ),

Step 2.2, using consecutive point as new reference point, successively hoist and lower both direction chooses new consecutive point, repeating step 2.1, numerical solution makes new advances the gasoloid backscattering coefficient β on consecutive point ₁(θ _c+ d θ), in vertical direction, the number of each consecutive point elects 3000 as, until obtain the gasoloid backscattering coefficient value in investigative range on all selected height, obtains gasoloid backscattering coefficient β ₁(θ) profile;

Step 3 is that gasoloid obtains the profile of gasoloid phase function than the definition of phase function by the gasoloid phase function on θ angle and the ratio of gasoloid backscattering coefficient.

Finally,

First gasoloid backscattering coefficient is substituted into Backscattering lidar equation

$P\left(z\right)=\mathrm{C\&eta;}\left(z\right)\frac{{\mathrm{\&beta;}}_1\left(z\right)+{\mathrm{\&beta;}}_2\left(z\right)}{z^2}\&times;\exp \{-2{\&Integral;}_0^z[{\mathrm{\&alpha;}}_1\left(z\right)+{\mathrm{\&alpha;}}_2\left(z\right)]\&times;\mathrm{dz}\}$ In, the P (z) in equation for the atmospheric backscatter echoed signal at laser radar receiving range z place, C be the constant that laser radar system comprises energy, η (z) is geometric factor, β ₁(z), β ₂z () is respectively gasoloid backscattering coefficient and the atmospheric molecule backscattering coefficient at distance z place, α ₁(z), α ₂z () is respectively Aerosol Extinction and the atmospheric molecule extinction coefficient at distance z place, dz is height resolution.Re-use the geometric factor that process of iteration obtains back scattering laser radar; Wherein, the step using process of iteration to obtain back scattering laser radar geometric factor is:

Step 1, first records gasoloid backscattering coefficient β by use CCD camera ₁(θ) variable in---bias angle theta is converted to gasoloid backscattering coefficient β in Backscattering lidar equation ₁variable in (z)---distance z, pass is between the two z=D/tan (π-θ), wherein, D is the vertical range of CCD camera and laser radar transmitted beam, and the initial geometric factor resetting the back scattering laser radar of zone of transition is η ' (z)=1;

Step 2, substitutes into Backscattering lidar equation by the geometric factor of setting $P\left(z\right)=\mathrm{C\&eta;}\left(z\right)\frac{{\mathrm{\&beta;}}_1\left(z\right)+{\mathrm{\&beta;}}_2\left(z\right)}{z^2}\&times;\exp \{-2{\&Integral;}_0^z[{\mathrm{\&alpha;}}_1\left(z\right)+{\mathrm{\&alpha;}}_2\left(z\right)]\&times;\mathrm{dz}\}$ In, use Fernald method to obtain gasoloid backscattering coefficient β ' ₁(z);

Step 3, by the gasoloid backscattering coefficient β ' obtained ₁(z) and the gasoloid backscattering coefficient β through changing using CCD camera to record ₁z () compares, draw ratio beta ' ₁(z)/β ₁(z);

Step 4, if ratio beta ' ₁(z)/β ₁(z) <0.98, then the geometric factor resetting the back scattering laser radar of zone of transition be last geometric factor be multiplied by ratio beta ' ₁(z)/β ₁after (z), repeat step 2 ~ 3, until ratio beta ' ₁(z)/β ₁z ()>=0.98, obtains the geometric factor of the back scattering laser radar as shown in the pecked line in Fig. 1.

Obviously, those skilled in the art can carry out various change and modification to the measuring method of back scattering laser radar geometric factor of the present invention and not depart from the spirit and scope of the present invention.Like this, if belong within the scope of the claims in the present invention and equivalent technologies thereof to these amendments of the present invention and modification, then the present invention is also intended to comprise these change and modification.

Claims (5)

1. a measuring method for back scattering laser radar geometric factor, comprises and uses CCD camera to record gasoloid backscattering coefficient, it is characterized in that key step is as follows:

First gasoloid backscattering coefficient is substituted into Backscattering lidar equation $P\left(z\right)=C\mathrm{\&eta;}\left(z\right)\frac{{\mathrm{\&beta;}}_1\left(z\right)+{\mathrm{\&beta;}}_2\left(z\right)}{z^2}\&times;\exp \{-2{\&Integral;}_0^z\&lsqb;{\mathrm{\&alpha;}}_1\left(z\right)+{\mathrm{\&alpha;}}_2\left(z\right)\&rsqb;\&times;dz\}$ In, the P (z) in equation for the atmospheric backscatter echoed signal at laser radar receiving range z place, C be the constant that laser radar system comprises energy, η (z) is geometric factor, β ₁(z), β ₂z () is respectively gasoloid backscattering coefficient and the atmospheric molecule backscattering coefficient at distance z place, α ₁(z), α ₂z () is respectively Aerosol Extinction and the atmospheric molecule extinction coefficient at distance z place, dz is height resolution; Re-use the geometric factor that process of iteration obtains back scattering laser radar, wherein, the step using process of iteration to obtain back scattering laser radar geometric factor is:

Step 1, the initial geometric factor of the back scattering laser radar of setting zone of transition is η ' (z)=1;

Step 2, substitutes into Backscattering lidar equation by the geometric factor of setting $P\left(z\right)=C\mathrm{\&eta;}\left(z\right)\frac{{\mathrm{\&beta;}}_1\left(z\right)+{\mathrm{\&beta;}}_2\left(z\right)}{z^2}\&times;\exp \{-2{\&Integral;}_0^z\&lsqb;{\mathrm{\&alpha;}}_1\left(z\right)+{\mathrm{\&alpha;}}_2\left(z\right)\&rsqb;\&times;dz\}$ In, use Fernald method to obtain gasoloid backscattering coefficient β ' ₁(z);

Step 3, by the gasoloid backscattering coefficient β ' obtained ₁z () compares with using the gasoloid backscattering coefficient that records of CCD camera, draw ratio beta ' ₁(z)/β ₁(z);

Step 4, if ratio beta ' ₁(z)/β ₁(z) <0.98, then the geometric factor resetting the back scattering laser radar of zone of transition be last geometric factor be multiplied by ratio beta ' ₁(z)/β ₁after (z), repeat step 2 ~ 3, until ratio beta ' ₁(z)/β ₁z ()>=0.98, obtains the geometric factor of back scattering laser radar.

2. the measuring method of back scattering laser radar geometric factor according to claim 1, is characterized in that the distance between CCD camera and transmitted beam is 5 ~ 200m.

3. the measuring method of back scattering laser radar geometric factor according to claim 1, is characterized in that CCD camera is less than in the half-light subnumber that-20 degree are lower that 1 photon number/pixel, always subtended angle are greater than 60 degree, resolution angle is less than 0.03 degree/pixel.

4. the measuring method of back scattering laser radar geometric factor according to claim 1, is characterized in that the wavelength of back scattering laser radar is 532nm, pulse energy >=50mJ.

5. the measuring method of back scattering laser radar geometric factor according to claim 1, is characterized in that the process using CCD camera to record gasoloid backscattering coefficient is:

Step 1, first CCD side direction laser radar is operated in air compared with in the horizontal direction in non-uniform time section, the gasoloid of selected scattering angle to be 179 ~ 180 degree of places be reference point is all 1 than phase function value and atmospheric molecule than phase function value, record the gasoloid backscattering coefficient value in reference point again, and assert that this value is all equal with the gasoloid backscattering coefficient value at scattering angle place each in horizontal direction, afterwards

Step 1.1, substitutes into side direction laser radar equation formula with reference to the bias angle theta of the gasoloid backscattering coefficient value on point and gasoloid pixel more each than phase function value and CCD camera, angular breadth d θ, CCD camera together with the vertical range D of laser radar transmitted beam in, the signal intensity that the P (θ) in equation receives for respective pixel on direction, θ drift angle, P ₀for the power of laser radar transmitted beam, K is the optical transmittance of receiving system, and A is the useful area of optical system, T _t, T _rbe respectively the transmitance on laser vertical direction and tilted direction, β (θ) is gasoloid lateral scattering coefficient, and it is by β (θ)=β ₁(θ) f ₁(θ)+β ₂(θ) f ₂(θ) form, the β in formula ₁(θ) be gasoloid backscattering coefficient, β ₂(θ) be atmospheric molecule backscattering coefficient, f ₁(θ) for gasoloid is than phase function, f ₂(θ) for atmospheric molecule is than phase function, Inversion Calculation goes out gasoloid on reference point consecutive point than phase function value by the following method,

If reference point scattering angle is θ _c, gasoloid backscattering coefficient is β ₁(θ _c), the optical thickness of air is τ _c, get constant side direction laser radar signal β ' (θ) then with decay is defined as

${\mathrm{\&beta;}}^{\&prime;}\left(\mathrm{\&theta;}\right)=\frac{P\left(\mathrm{\&theta;}\right)}{C}$ ①，

The expression formula of the side direction laser radar signal in theory with decay is,

β′(θ)＝[β ₁(θ)f(θ) ₁+β ₂(θ)f ₂(θ)]exp-(Δτ+τ _c(1/cos(π-θ)-1/cos(π-θ _c))+Δτ/cos(π-θ))dθ

②，

Δ τ in formula is that scattering angle is from θ _cto the SEQUENCING VERTICAL optical thickness at θ place, from reference point, use numerical algorithm, fit equation is formula and 2. formula 1., and numerical value solves gasoloid on reference point consecutive point than phase function f ₁(θ _c+ d θ),

Step 1.2, using consecutive point as new reference point, chooses new consecutive point to the direction that scattering angle diminishes, and repeat step 1.1, the gasoloid that numerical solution makes new advances on consecutive point is than phase function f ₁(θ _c+ d θ), until the gasoloid of all selected scattering angle, than phase function value, obtains gasoloid than phase function f in acquisition investigative range ₁(θ) profile;

Step 2, first CCD side direction laser radar is operated in surface level on perpendicular direction, and assert that gasoloid in the horizontal direction that obtained by step 1 is than equal with in vertical direction of phase function value, the somewhere chosen again on detection height is as a reference point, record the gasoloid backscattering coefficient value on this aspect, afterwards

Step 2.1, substitutes into side direction laser radar equation formula with reference to the bias angle theta of the gasoloid backscattering coefficient value on point and gasoloid pixel more each than phase function value and CCD camera, angular breadth d θ, CCD camera together with the vertical range D of laser radar transmitted beam in, Inversion Calculation goes out the gasoloid backscattering coefficient value on reference point consecutive point by the following method,

If reference point scattering angle is θ _c, gasoloid backscattering coefficient is β ₁(θ _c), the optical thickness of air is τ _c, get constant side direction laser radar signal β ' (θ) then with decay is defined as

${\mathrm{\&beta;}}^{\&prime;}\left(\mathrm{\&theta;}\right)=\frac{P\left(\mathrm{\&theta;}\right)}{C}$ ①，

The expression formula of the side direction laser radar signal in theory with decay is,

β′(θ)＝[β ₁(θ)f(θ) ₁+β ₂(θ)f ₂(θ)]exp-(Δτ+τ _c(1/cos(π-θ)-1/cos(π-θ _c))+Δτ/cos(π-θ))dθ

②，

Δ τ in formula is that scattering angle is from θ _cto the SEQUENCING VERTICAL optical thickness at θ place, from reference point, use numerical algorithm, fit equation is formula and 2. formula 1., and numerical value solves the gasoloid backscattering coefficient β on reference point consecutive point ₁(θ _c+ d θ),

Step 2.2, using consecutive point as new reference point, successively hoist and lower both direction chooses new consecutive point, repeating step 2.1, numerical solution makes new advances the gasoloid backscattering coefficient β on consecutive point ₁(θ _c+ d θ), until obtain the gasoloid backscattering coefficient value in investigative range on all selected height, obtain gasoloid backscattering coefficient β ₁(θ) profile;

Step 3 is that gasoloid obtains the profile of gasoloid phase function than the definition of phase function by the gasoloid phase function on θ angle and the ratio of gasoloid backscattering coefficient.