CN103454244A - Measuring method for radiation characteristics of semitransparent medium based on multi-frequency modulation laser irradiation - Google Patents

Abstract

The invention provides a measuring method for radiation characteristics of a semitransparent medium based on multi-frequency modulation laser irradiation, belongs to the technical field of semitransparent medium radiation characteristic measurement, and solves the problem in the semitransparent medium radiation characteristic measurement that a measurement result error of measurement information of one time is greater. Based on a multi-frequency modulation laser irradiation technology, the measuring method utilizes multi-frequency modulation laser to irradiate the surface of the semitransparent medium with a coating with certain blackness; frequency domain semi-sphere reflection signals of a plurality of groups of boundaries are obtained by changing a laser modulation frequency, a laser incident angle, the thickness of a test piece and the blackness of the coating of the test piece; irradiation physical property parameters of the semitransparent medium are obtained based on the reflection signals by combining an inverse problem solving technology. The measuring method for the radiation characteristics of the semitransparent medium based on the multi-frequency modulation laser irradiation is used for measuring the radiation characteristics of the semitransparent medium.

Description

Translucent medium radiation characteristic measuring method based on multifrequency modulated laser irradiation

Technical field

The present invention relates to the translucent medium radiation characteristic measuring method based on multifrequency modulated laser irradiation, belong to translucent medium radiation characteristic field of measuring technique.

Background technology

Translucent medium has a wide range of applications in scientific domains such as commercial production, biomedicine, information communications.The physical parameter of research translucent medium has important practical significance in a lot of fields, such as Non-Destructive Testing, Laser Processing manufacture (as cutting glass by laser, liquid crystal panel etc.).In recent years, along with the develop rapidly of the modern high technologies such as the infrared characteristic of Aero-Space, infrared acquisition, target and environment, laser, electron device, biomedicine, understand the translucent medium thermal physical property parameter and become particularly important.Therefore the research of carrying out translucent medium heat radiation physical property and related discipline is all significant for dual-use field.

Absorption coefficient and scattering coefficient are the important parameters that characterizes translucent medium heat radiation physical property.Deeply understand this thermal physical property parameter and it is carried out to experiment measuring and theoretical analysis, the significant and using value for fields such as metal processing, medical imaging technology, harmless laser therapy technology, particle detection research, infrared remote sensing technology, material science and environmental monitorings.

Can use continuous light source and detector in frequency domain method, it incident pulse Ear Mucosa Treated by He Ne Laser Irradiation measured sample once after, can decomposite the light signal under a lot of frequency domains, also just can think once to survey to have obtained multipacket message.In the actual measurement process, there is certain measuring error in experimental facilities, and some working condition measuring signal is fainter, and single information can not complete the measurement of radiation physical property.

Summary of the invention

The present invention seeks in order to solve in the measurement of translucent medium radiation characteristic, the problem that the measuring result error of single measurement information is larger, provide a kind of translucent medium radiation characteristic measuring method based on multifrequency modulated laser irradiation.

Translucent medium radiation characteristic measuring method based on multifrequency modulated laser irradiation of the present invention, it comprises the following steps:

Step 1: the setting sampling number is N, and N is greater than or equal to 2 natural number;

Step 2: getting thickness is L _itranslucent medium test specimen to be measured, it is ε that a side of this translucent medium test specimen to be measured evenly scribbles blackness _iopaque coating, the employing angular frequency is ω _ilaser beam irradiation translucent medium test specimen without coating one side, this laser beam becomes θ with the normal direction of translucent medium test specimen _iangle, used detector measurement to obtain the multiple hemisphere reflected signal of frequency domain on N group translucent medium test specimen surface-boundary ${\hat{R}}_{i,\mathrm{mea}}\left({\mathrm{\ω}}_i\right);i=\mathrm{1,2,3},......,N;$

Step 3: utilize the inverse problem algorithm, set the absorption coefficient κ of translucent medium test specimen _awith scattering coefficient κ _svalue;

Step 4: according to absorption coefficient κ _awith scattering coefficient κ _svalue, by the solving of radiation transfer equation, obtain N radiation intensity field in computational fields;

Step 5: utilize in step 4 and to calculate N the radiation intensity field obtained, calculate obtain the translucent medium test specimen without the hemisphere reflected signal estimated value again of the frequency domain on coating one lateral boundaries

${\hat{R}}_{i,\mathrm{est}}\left({\mathrm{\ω}}_i\right)=2\mathrm{\π}{\∫}_{\mathrm{\π}/2}^{\mathrm{\π}}\frac{{\hat{I}}_i(\mathrm{\θ},{\mathrm{\ω}}_i)}{{\hat{I}}_0}\cos \mathrm{\θ}\sin \mathrm{\θd\θ},$

In formula

that angular frequency is ω _ithe radiation intensity value of laser beam,

for angular frequency is ω _ilaser beam the translucent medium test specimen without the radiation intensity on coating one lateral boundaries, θ is the scattering direction;

Step 6: according to the multiple hemisphere reflected signal estimated value of the frequency domain obtained in step 5

with the multiple hemisphere reflected signal of the frequency domain obtained in step 2

calculate the target function value F obtained in the inverse problem algorithm _obj:

$F_{\mathrm{obj}}=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{[{\hat{R}}_{i,\mathrm{est}}\left({\mathrm{\ω}}_i\right)-{\hat{R}}_{i,\mathrm{mea}}\left({\mathrm{\ω}}_i\right)]}^2;$

Step 7: by target function value F _objwith the threshold xi presetted, compare, if target function value F _objbe less than threshold xi, by current absorption coefficient κ _awith scattering coefficient κ _svalue as the feature measurement result of translucent medium test specimen to be measured, complete the measurement of translucent medium radiation characteristic; Otherwise, according to the inverse problem algorithm, revise absorption coefficient κ _awith scattering coefficient κ _svalue, return to step 4.

Described laser beam adopts the adjustable sinusoidal light source of amplitude to produce.

Described inverse problem algorithm is ant group algorithm.

The concrete grammar that obtains N radiation intensity field in computational fields in described step 4 is:

According to following radiation transfer equation, it is solved to acquisition:

$\frac{j{\mathrm{\ω}}_i}{c}{\hat{I}}_i(x,\mathrm{\θ},{\mathrm{\ω}}_i)+\frac{\∂{\hat{I}}_i(x,\mathrm{\θ},{\mathrm{\ω}}_i)}{\∂x}=-\mathrm{\β}{\hat{I}}_c(x,{\mathrm{\ω}}_i)+\frac{{\mathrm{\κ}}_s}{2}{\∫}_0^{\mathrm{\π}}{\hat{I}}_i(L_i,{\mathrm{\θ}}^{\′},{\mathrm{\ω}}_i)\mathrm{\Φ}({\mathrm{\θ}}^{\′},\mathrm{\θ})\sin {\mathrm{\θ}}^{\′}d{\mathrm{\θ}}^{\′},$

${\hat{I}}_i(0,\mathrm{\&theta;},{\mathrm{\&omega;}}_i)=(1-{\mathrm{\&rho;}}_0){\hat{I}}_c({\mathrm{\&omega;}}_i,{\mathrm{\&theta;}}_i)+2{\mathrm{\&rho;}}_1{\&Integral;}_{\mathrm{\&pi;}/2}^{\mathrm{\&pi;}}{\hat{I}}_i(0,{\mathrm{\&theta;}}^{\&prime;}{,\mathrm{\&omega;}}_i)\cos {\mathrm{\&theta;}}^{\&prime;}\sin {\mathrm{\&theta;}}^{\&prime;}d{\mathrm{\&theta;}}^{\&prime;},0\&le;\mathrm{\&theta;}<\mathrm{\&pi;}/2,$

${\hat{I}}_i(L_i,\mathrm{\&theta;},{\mathrm{\&omega;}}_i)=0,\mathrm{\&pi;}/2\&le;\mathrm{\&theta;}<\mathrm{\&pi;},$

In formula, c is the velocity of propagation of laser beam in translucent medium test specimen to be measured,

for angular frequency is ω _ilaser beam along the θ direction radiation intensity value at the x place, x is position, radiation intensity to be asked field and the translucent medium test specimen to be measured horizontal range without coating one lateral boundaries, β is attenuation coefficient, for angular frequency is ω _ilaser beam in the radiation intensity at x place,

for angular frequency is ω _ilaser beam along θ ' direction at x=L _ithe radiation intensity value at place, θ ' is for projecting the radiation direction of the laser beam at x place, position in radiation field, Φ (θ ', be θ) from θ ' direction incident the Scattering Phase Function that scatters out from the θ direction, ρ ₀the reflectivity of laser beam while by environment, entering translucent medium test specimen to be measured, ρ ₁reflectivity for laser beam during by translucent medium test specimen entered environment to be measured,

for angular frequency is ω _ilaser beam along θ _ithe radiation intensity of angle incident translucent medium test specimen to be measured,

for angular frequency is ω _ilaser beam at the x=0 place along the radiation intensity value of θ ' direction,

for angular frequency is ω _ilaser beam along the θ direction at x=L _ithe radiation intensity value at place.

Angular frequency is ω _ilaser beam in the radiation intensity at x place

by following formula, obtain:

${\hat{I}}_c(x,{\mathrm{\&omega;}}_i)={\hat{I}}_0\exp [-({\mathrm{\&kappa;}}_a+{\mathrm{\&kappa;}}_s)x-{\mathrm{j\&omega;}}_i\left(\frac{x}{c}\right)].$

Advantage of the present invention: the present invention is based on multifrequency modulated laser irradiation technique, utilize the multifrequency modulated laser to irradiate the translucent medium surface with certain blackness coating, obtain the frequency domain hemisphere reflected signal of many group boundaries by changing Laser Modulation frequency, laser incident angle, specimen thickness and test specimen coating blackness, obtain the radiation physical parameter of translucent medium based on these reflected signals in conjunction with the inverse problem solution technique.The present invention by foundation measure translucent medium radiation physical property just, the inverse problem model, under the prerequisite of other physical parameters of known media, proposed to utilize the method for many information inverse problem solution technique Measurement accuracy translucent medium absorption coefficient and scattering coefficient, make the measurement result of translucent medium radiation characteristic more accurate, improve the inverse problem solving precision, can rebuild more exactly absorption coefficient and the scattering coefficient of translucent medium inside.

The accompanying drawing explanation

Fig. 1 is in the translucent medium radiation characteristic measuring method based on multifrequency modulated laser irradiation of the present invention, and translucent medium test specimen to be measured is subject to the radiation transmission schematic diagram of laser beam irradiation; In figure, solid arrow is the parallel incident direction of square pulse laser beam, and the empty direction of arrow is hemisphere frequency domain reflection sense.

Embodiment

Embodiment one: below in conjunction with Fig. 1, present embodiment is described, the described translucent medium radiation characteristic measuring method based on multifrequency modulated laser irradiation of present embodiment, it comprises the following steps:

Step 1: the setting sampling number is N, and N is greater than or equal to 2 natural number;

Step 2: getting thickness is L _itranslucent medium test specimen to be measured, it is ε that a side of this translucent medium test specimen to be measured evenly scribbles blackness _iopaque coating, the employing angular frequency is ω _ilaser beam irradiation translucent medium test specimen without coating one side, this laser beam becomes θ with the normal direction of translucent medium test specimen _iangle, used detector measurement to obtain the multiple hemisphere reflected signal of frequency domain on N group translucent medium test specimen surface-boundary ${\hat{R}}_{i,\mathrm{mea}}\left({\mathrm{\&omega;}}_i\right);i=\mathrm{1,2,3},......,N;$

Step 3: utilize the inverse problem algorithm, set the absorption coefficient κ of translucent medium test specimen _awith scattering coefficient κ _svalue;

Step 4: according to absorption coefficient κ _awith scattering coefficient κ _svalue, by the solving of radiation transfer equation, obtain N radiation intensity field in computational fields;

Step 5: utilize in step 4 and to calculate N the radiation intensity field obtained, calculate obtain the translucent medium test specimen without the hemisphere reflected signal estimated value again of the frequency domain on coating one lateral boundaries

${\hat{R}}_{i,\mathrm{est}}\left({\mathrm{\&omega;}}_i\right)=2\mathrm{\&pi;}{\&Integral;}_{\mathrm{\&pi;}/2}^{\mathrm{\&pi;}}\frac{{\hat{I}}_i(\mathrm{\&theta;},{\mathrm{\&omega;}}_i)}{{\hat{I}}_0}\cos \mathrm{\&theta;}\sin \mathrm{\&theta;d\&theta;},$

In formula

that angular frequency is ω _ithe radiation intensity value of laser beam,

for angular frequency is ω _ilaser beam the translucent medium test specimen without the radiation intensity on coating one lateral boundaries, θ is the scattering direction;

Step 6: according to the multiple hemisphere reflected signal estimated value of the frequency domain obtained in step 5

with the multiple hemisphere reflected signal of the frequency domain obtained in step 2

calculate the target function value F obtained in the inverse problem algorithm _obj:

$F_{\mathrm{obj}}=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{[{\hat{R}}_{i,\mathrm{est}}\left({\mathrm{\&omega;}}_i\right)-{\hat{R}}_{i,\mathrm{mea}}\left({\mathrm{\&omega;}}_i\right)]}^2;$

Step 7: by target function value F _objwith the threshold xi presetted, compare, if target function value F _objbe less than threshold xi, by current absorption coefficient κ _awith scattering coefficient κ _svalue as the feature measurement result of translucent medium test specimen to be measured, complete the measurement of translucent medium radiation characteristic; Otherwise, according to the inverse problem algorithm, revise absorption coefficient κ _awith scattering coefficient κ _svalue, return to step 4.

In present embodiment, laser beam is the laser beam of the characteristic frequency of the adjustable sinusoidal light source generation of employing amplitude.Target function value F _objoften once compare with the threshold xi presetted, if be more than or equal to threshold xi, all can revise absorption coefficient κ _awith scattering coefficient κ _svalue, then return to step 4, according to amended absorption coefficient κ _awith scattering coefficient κ _svalue, then recalculate, until target function value F _objbe less than threshold xi.

Embodiment two: present embodiment is described further embodiment one, and the described laser beam of present embodiment adopts the adjustable sinusoidal light source of amplitude to produce.

Embodiment three: present embodiment is described further embodiment one or two, and the described inverse problem algorithm of present embodiment is ant group algorithm.

Embodiment four: present embodiment is described further embodiment one, two or three, and the concrete grammar that obtains N radiation intensity field in computational fields in the described step 4 of present embodiment is:

According to following radiation transfer equation, it is solved to acquisition:

$\frac{j{\mathrm{\&omega;}}_i}{c}{\hat{I}}_i(x,\mathrm{\&theta;},{\mathrm{\&omega;}}_i)+\frac{\&PartialD;{\hat{I}}_i(x,\mathrm{\&theta;},{\mathrm{\&omega;}}_i)}{\&PartialD;x}=-\mathrm{\&beta;}{\hat{I}}_c(x,{\mathrm{\&omega;}}_i)+\frac{{\mathrm{\&kappa;}}_s}{2}{\&Integral;}_0^{\mathrm{\&pi;}}{\hat{I}}_i(L_i,{\mathrm{\&theta;}}^{\&prime;},{\mathrm{\&omega;}}_i)\mathrm{\&Phi;}({\mathrm{\&theta;}}^{\&prime;},\mathrm{\&theta;})\sin {\mathrm{\&theta;}}^{\&prime;}d{\mathrm{\&theta;}}^{\&prime;},$

${\hat{I}}_i(0,\mathrm{\&theta;},{\mathrm{\&omega;}}_i)=(1-{\mathrm{\&rho;}}_0){\hat{I}}_c({\mathrm{\&omega;}}_i,{\mathrm{\&theta;}}_i)+2{\mathrm{\&rho;}}_1{\&Integral;}_{\mathrm{\&pi;}/2}^{\mathrm{\&pi;}}{\hat{I}}_i(0,{\mathrm{\&theta;}}^{\&prime;}{\mathrm{\&omega;}}_i)\cos {\mathrm{\&theta;}}^{\&prime;}\sin {\mathrm{\&theta;}}^{\&prime;}d{\mathrm{\&theta;}}^{\&prime;},0\&le;\mathrm{\&theta;}<\mathrm{\&pi;}/2,$

${\hat{I}}_i(L_i,\mathrm{\&theta;},{\mathrm{\&omega;}}_i)=0,\mathrm{\&pi;}/2\&le;\mathrm{\&theta;}<\mathrm{\&pi;},$

In formula, c is the velocity of propagation of laser beam in translucent medium test specimen to be measured,

for angular frequency is ω _ilaser beam along the θ direction radiation intensity value at the x place, x is position, radiation intensity to be asked field and the translucent medium test specimen to be measured horizontal range without coating one lateral boundaries, β is attenuation coefficient,

for angular frequency is ω _ilaser beam in the radiation intensity at x place,

for angular frequency is ω _ilaser beam along θ ' direction at x=L _ithe radiation intensity value at place, θ ' is for projecting the radiation direction of the laser beam at x place, position in radiation field, Φ (θ ', be θ) from θ ' direction incident the Scattering Phase Function that scatters out from the θ direction, ρ ₀the reflectivity of laser beam while by environment, entering translucent medium test specimen to be measured, ρ ₁reflectivity for laser beam during by translucent medium test specimen entered environment to be measured,

for angular frequency is ω _ilaser beam along θ _ithe radiation intensity of angle incident translucent medium test specimen to be measured,

for angular frequency is ω _ilaser beam at the x=0 place along the radiation intensity value of θ ' direction, for angular frequency is ω _ilaser beam along the θ direction at x=L _ithe radiation intensity value at place.

Embodiment five: present embodiment is described further embodiment four, and in present embodiment, angular frequency is ω _ilaser beam in the radiation intensity at x place by following formula, obtain:

${\hat{I}}_c(x,{\mathrm{\&omega;}}_i)={\hat{I}}_0\exp [-({\mathrm{\&kappa;}}_a+{\mathrm{\&kappa;}}_s)x-{\mathrm{j\&omega;}}_i\left(\frac{x}{c}\right)].$

Claims (5)

1. the translucent medium radiation characteristic measuring method based on multifrequency modulated laser irradiation, is characterized in that, it comprises the following steps:

Step 1: the setting sampling number is N, and N is greater than or equal to 2 natural number;

Step 2: getting thickness is L _itranslucent medium test specimen to be measured, it is ε that a side of this translucent medium test specimen to be measured evenly scribbles blackness _iopaque coating, the employing angular frequency is ω _ilaser beam irradiation translucent medium test specimen without coating one side, this laser beam becomes θ with the normal direction of translucent medium test specimen _iangle, used detector measurement to obtain the multiple hemisphere reflected signal of frequency domain on N group translucent medium test specimen surface-boundary ${\hat{R}}_{i,\mathrm{mea}}\left({\mathrm{\&omega;}}_i\right);i=\mathrm{1,2,3},......,N;$

Step 3: utilize the inverse problem algorithm, set the absorption coefficient κ of translucent medium test specimen _awith scattering coefficient κ _svalue;

Step 4: according to absorption coefficient κ _awith scattering coefficient κ _svalue, by the solving of radiation transfer equation, obtain N radiation intensity field in computational fields;

Step 5: utilize in step 4 and to calculate N the radiation intensity field obtained, calculate obtain the translucent medium test specimen without the hemisphere reflected signal estimated value again of the frequency domain on coating one lateral boundaries

${\hat{R}}_{i,\mathrm{est}}\left({\mathrm{\&omega;}}_i\right)=2\mathrm{\&pi;}{\&Integral;}_{\mathrm{\&pi;}/2}^{\mathrm{\&pi;}}\frac{{\hat{I}}_i(\mathrm{\&theta;},{\mathrm{\&omega;}}_i)}{{\hat{I}}_0}\cos \mathrm{\&theta;}\sin \mathrm{\&theta;d\&theta;},$

In formula that angular frequency is ω _ithe radiation intensity value of laser beam,

for angular frequency is ω _ilaser beam the translucent medium test specimen without the radiation intensity on coating one lateral boundaries, θ is the scattering direction;

Step 6: according to the multiple hemisphere reflected signal estimated value of the frequency domain obtained in step 5 with the multiple hemisphere reflected signal of the frequency domain obtained in step 2

calculate the target function value F obtained in the inverse problem algorithm _obj:

$F_{\mathrm{obj}}=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{[{\hat{R}}_{i,\mathrm{est}}\left({\mathrm{\&omega;}}_i\right)-{\hat{R}}_{i,\mathrm{mea}}\left({\mathrm{\&omega;}}_i\right)]}^2;$

Step 7: by target function value F _objwith the threshold xi presetted, compare, if target function value F _objbe less than threshold xi, by current absorption coefficient κ _awith scattering coefficient κ _svalue as the feature measurement result of translucent medium test specimen to be measured, complete the measurement of translucent medium radiation characteristic; Otherwise, according to the inverse problem algorithm, revise absorption coefficient κ _awith scattering coefficient κ _svalue, return to step 4.

2. the translucent medium radiation characteristic measuring method based on multifrequency modulated laser irradiation according to claim 1, is characterized in that, described laser beam adopts the adjustable sinusoidal light source of amplitude to produce.

3. the translucent medium radiation characteristic measuring method based on multifrequency modulated laser irradiation according to claim 1 and 2, is characterized in that, described inverse problem algorithm is ant group algorithm.

4. the translucent medium radiation characteristic measuring method based on multifrequency modulated laser irradiation according to claim 3, is characterized in that, the concrete grammar that obtains N radiation intensity field in computational fields in described step 4 is:

According to following radiation transfer equation, it is solved to acquisition:

$\frac{j{\mathrm{\&omega;}}_i}{c}{\hat{I}}_i(x,\mathrm{\&theta;},{\mathrm{\&omega;}}_i)+\frac{\&PartialD;{\hat{I}}_i(x,\mathrm{\&theta;},{\mathrm{\&omega;}}_i)}{\&PartialD;x}=-\mathrm{\&beta;}{\hat{I}}_c(x,{\mathrm{\&omega;}}_i)+\frac{{\mathrm{\&kappa;}}_s}{2}{\&Integral;}_0^{\mathrm{\&pi;}}{\hat{I}}_i(L_i,{\mathrm{\&theta;}}^{\&prime;},{\mathrm{\&omega;}}_i)\mathrm{\&Phi;}({\mathrm{\&theta;}}^{\&prime;},\mathrm{\&theta;})\sin {\mathrm{\&theta;}}^{\&prime;}d{\mathrm{\&theta;}}^{\&prime;},$

${\hat{I}}_i(0,\mathrm{\&theta;},{\mathrm{\&omega;}}_i)=(1-{\mathrm{\&rho;}}_0){\hat{I}}_c({\mathrm{\&omega;}}_i,{\mathrm{\&theta;}}_i)+2{\mathrm{\&rho;}}_1{\&Integral;}_{\mathrm{\&pi;}/2}^{\mathrm{\&pi;}}{\hat{I}}_i(0,{\mathrm{\&theta;}}^{\&prime;},{\mathrm{\&omega;}}_i)\cos {\mathrm{\&theta;}}^{\&prime;}\sin {\mathrm{\&theta;}}^{\&prime;}d{\mathrm{\&theta;}}^{\&prime;},0\&le;\mathrm{\&theta;}<\mathrm{\&pi;}/2,$

${\hat{I}}_i(L_i,\mathrm{\&theta;},{\mathrm{\&omega;}}_i)=0,\mathrm{\&pi;}/2\&le;\mathrm{\&theta;}<\mathrm{\&pi;},$

In formula, c is the velocity of propagation of laser beam in translucent medium test specimen to be measured,

for angular frequency is ω _ilaser beam along the θ direction radiation intensity value at the x place, x is position, radiation intensity to be asked field and the translucent medium test specimen to be measured horizontal range without coating one lateral boundaries, β is attenuation coefficient,

for angular frequency is ω _ilaser beam in the radiation intensity at x place,

for angular frequency is ω _ilaser beam along θ ' direction at x=L _ithe radiation intensity value at place, θ ' is for projecting the radiation direction of the laser beam at x place, position in radiation field, Φ (θ ', be θ) from θ ' direction incident the Scattering Phase Function that scatters out from the θ direction, ρ ₀the reflectivity of laser beam while by environment, entering translucent medium test specimen to be measured, ρ ₁reflectivity for laser beam during by translucent medium test specimen entered environment to be measured,

for angular frequency is ω _ilaser beam along θ _ithe radiation intensity of angle incident translucent medium test specimen to be measured,

for angular frequency is ω _ilaser beam at the x=0 place along the radiation intensity value of θ ' direction,

for angular frequency is ω _ilaser beam along the θ direction at x=L _ithe radiation intensity value at place.

5. the translucent medium radiation characteristic measuring method based on multifrequency modulated laser irradiation according to claim 4, is characterized in that, angular frequency is ω _ilaser beam in the radiation intensity at x place by following formula, obtain:

${\hat{I}}_c(x,{\mathrm{\&omega;}}_i)={\hat{I}}_0\exp [-({\mathrm{\&kappa;}}_a+{\mathrm{\&kappa;}}_s)x-{\mathrm{j\&omega;}}_i\left(\frac{x}{c}\right)].$

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