CN106124410A - Single photoacoustic cell measures the new method of aerosol multi-wavelength absorptance simultaneously - Google Patents

Abstract

The invention discloses a kind of single photoacoustic cell and measure aerosol method of absorptance at multiple wavelength simultaneously.The frequency interval that the laser instrument of multiple different wave lengths is sent by functional generator is that the square-wave signal of df carries out Modulation and Amplitude Modulation, the laser of different wave length enters the aerosol interaction injecting in photoacoustic cell, and photoacoustic cell after optical-fiber bundling device closes bundle and produces the photoacoustic signal P of reaction gas sol particles absorption signal_m(f₀±f)；Absorptance formula according to the different modulating frequency derived is calculated aerosol absorptance at multiple wavelength.This method overcomes the sample space-time inhomogeneities and the problem of particle loss caused when multiple photoacoustic cell is measured, and measures process simpler, and system structure is compacter.The method utilizing the present invention can obtain aerocolloidal absorptionIndex, and aerocolloidal composition can be identified, thus tracing to the source and administering the decision-making foundation providing valuable for haze.

Description

Single photoacoustic cell measures the new method of aerosol multi-wavelength absorptance simultaneously

Technical field

This method belongs to optical field.The present invention relates to a kind of single photoacoustic cell and measure aerosol simultaneously at multiple wavelength The new method of optical absorption coefficient, the method utilizes optoacoustic spectroscopy to combine Fourier transformation data processing method, it is achieved gas The real-time online measuring of colloidal sol optical absorption coefficient wavelength-dependent behavior.

Background technology

Along with the quick growth of China's economy, the production such as commercial production, urban transportation, the life activity dirt to atmospheric environment Dye is more serious, and big region, long haze weather are the most frequent, and this is to the sound development of national economy, national body Body health causes serious threat, and therefore tracing to the source haze and administering the most targetedly seems particularly Urgent.Atmospheric aerosol is one of main reason of haze, and the analysis to its composition is by the effective means that haze is traced to the source.

The optical characteristics of atmospheric aerosol includes absorbing and scattering, and sum of the two is delustring.Aerocolloidal absorption and scattering With different wave length (λ₁, λ₂) relation of incident illumination is satisfied by following exponential relationship (as a example by absorbing):

$\frac{{\mathrm{\β}}_{abs}\left({\mathrm{\λ}}_1\right)}{{\mathrm{\β}}_{abs}\left({\mathrm{\λ}}_2\right)}={\left(\frac{{\mathrm{\λ}}_1}{{\mathrm{\λ}}_2}\right)}^{-AAC}---\left(1\right)$

Wherein, AAC is referred to as aerosol absorptionCoefficient.Equally, for aerosol scatteringCoefficient (SAC) definition is also such.The scattering power of incident illumination is depended on the particle size of optical definitions by aerosol, for spherical For particle, this parameter can be expressed as:

$x=\frac{2\mathrm{\π}r}{\mathrm{\λ}}---\left(2\right)$

Wherein r is particle radii, and λ is lambda1-wavelength, as can be seen from the above equation, and the aerosol scattering power to incident illumination Depend on the ratio of particle diameter and lambda1-wavelength.Different from scattering, in addition to aerosol particle diameter, its composition is also to affect it to incidence The key factor of light absorpting ability.Carbonaceous aerosol, as the main component of atmosphere pollution, is also that light main in air is inhaled Harvest divides.Showing according to research, the absorbability to light of carbon black is the strongest, its AAC close to 1, organic carbon and mineral airborne dust AAC value is the biggest, its AAC of aerosol that some biomass combustion produces up to more than 3, therefore can by aerosol not Absorption at co-wavelength measures, and obtains it and absorbsIndex also analyzes its composition, thus to aerocolloidal source Review.

At present, the instrument measuring atmospheric aerosol absorption characteristic uses filter technology mostly, and this technology is by measuring richness The collection aerosol on the filter membrane aerocolloidal absorptance of decay calculation to light, due to particulate nature suspended state Change and filter membrane greatly reduces the accuracy of measurement result to defects such as scattering of light.In site measurement aerosol absorptance Method mainly include that delustring subtracts scattering method, photothermal interference technology and optoacoustic spectroscopy etc..The principle that delustring subtracts scattering method is non- Often simple: to measure aerocolloidal extinction coefficient and scattering coefficient simultaneously and the two is subtracted each other the coefficient that can be absorbed, but the party Method is owing to measuring delustring and time during scattering and the inhomogeneities in space, and the error propagation of system causes the standard of the method Really property is substantially reduced.Photothermal interference technology is by the sky caused after particulate absorbs luminous energy in interferometer measurement detection light path The change of gas refractive index obtains aerocolloidal absorption information, and the sensitivity of this technology is the highest, yet with interferometer itself Sensitive to abnormal vibration so that the application of this technology is very restricted.

Optoacoustic spectroscopy falls within the category of photothermal technique, and the ultimate principle of this technology is optoacoustic effect, solid, gas Optoacoustic effect in body, liquid is all found in 19th century.The optoacoustic effect of particulate can be described as: when a branch of enter Penetrate light (modulation light or pulsed light) to be radiated on particle, particle absorption incident illumination energy and be heated and transfer heat to week The air enclosed, causes the cyclical heat of surrounding air to expand, and then produces sound wave (pressure wave), and sound wave can utilize mike The piezoelectric transducer such as (mike) or piezoelectric ceramics detects, and the size of the acoustic signals by recording can obtain particle Optical absorption characteristics information.Optoacoustic spectroscopy is high sensitivity " zero base line " spectral technique of a kind of wide dynamic range, Ke Yishi Time on-line measurement nature suspended state under the absorptance of particulate it is considered to be a kind of aerosol light of preferably measuring is inhaled Receive the technology of characteristic.

The multi-wavelength measurement apparatus based on optoacoustic spectroscopy of document report all uses multiple photoacoustic cell to measure gas respectively Colloidal sol absorptance at different wave length, therefore cannot ensure the homogeneity of spacetime of sample, and need to be to the pond of each photoacoustic cell Constant measures respectively, the complexity of the system operation of increase.The method that the present invention relates to can realize single photoacoustic cell Measure aerosol absorptance at multiple different wave lengths the most simultaneously, and then obtain the AAC of sample, it is achieved to sample composition Preliminary identification.

Summary of the invention

The present invention is mainly used to solve the system structure brought of multiple photoacoustic cells and behaviour during aerosol multi-wavelength absorptiometry The complexity problem made, it is provided that a kind of method utilizing single photoacoustic cell on-line measurement atmospheric aerosol wavelength-dependent behavior.This The space-time of the sample distribution that method causes due to gas distribution during can avoiding measuring uneven and in the process gas molten The loss problem of micelle, and according to measuring the aerosol wavelength dependency characteristic obtained, its composition can be identified.

Single photoacoustic cell measures the new method of aerosol multi-wavelength absorptance simultaneously, it is characterised in that: use signal function It is the square-wave signal of df that generator produces frequency interval, utilizes these square-wave signals that multiple optical fiber lasers are carried out power magnitude Modulation produces different frequency laser signal, and these different frequency laser signals are changed into by corresponding multiple optical fiber lasers accordingly The Output of laser of different wave length, the Output of laser of different wave length is carried out closing bundle by optical-fiber bundling device, light path vertically enters after adjusting Penetrating photoacoustic cell, and ensure the axis coinciding of optical axis and photoacoustic cell, in the Output of laser of different wave length and photoacoustic cell, aerosol is mutual Reaction gas sol particles absorption signal pressure wave signal is produced, simultaneously along original transmission direction injection light in acting on photoacoustic cell Sound pond is accepted by spectrogrph and is converted into electric signal storage to monitor in real time to computer accomplished different wave length laser light signal, Mike it is additionally provided with outside described photoacoustic cell, described pressure wave signal receives conversion through mike, preamplifier amplifies, Gathered by data collecting card after the demodulation of lock-in amplifier signal and carry out preservation at computer and obtain reaction gas sol particles and absorb The photoacoustic signal of signal, computer combines different wave length and obtains laser signal and photoacoustic signal carries out data analysis and obtains aerosol Absorptance at different wave length.

Utilize single photoacoustic cell to measure aerosol its theoretical foundation of the new method of absorptance at multiple wavelength to be simultaneously:

Its operating frequency of instrument based on resonance type optoacoustic spectroscopy is the resonant frequency of photoacoustic cell, for single wavelength For, laser instrument is to carry out amplitude-modulated with this resonant frequency.But, for multi-wavelength system, need to measure many simultaneously Individual light absorbs the sound pressure signal produced.If all of acoustical signal all on resonant frequency, then the signal that mike records is just Being the superposition of all acoustic pressures, respective signal just cannot be distinguished by out.Therefore, exist utilizing single photoacoustic cell to measure aerosol simultaneously During absorptance at multiple wavelength, the resonant frequency f that laser amplitude modulating frequency is photoacoustic cell of one of them wavelength₀, its The laser amplitude modulating frequency of commplementary wave length is distributed in its vicinity.As a example by three wavelength systems, the Modulation and Amplitude Modulation of three wavelength lasers Frequency is respectively as follows: f₀、f₀+df、f₀-df.Mike is P to the response of the photoacoustic signal on resonant frequency_m(f₀), deviation resonance frequency The photoacoustic signal response of rate is P_m(f₀± df), the representative value of df is 5Hz, and this value is sufficiently large for the resolution of signal, and also The resonant frequency of the close resonant cavity that can try one's best is to realize effective enhancing of photoacoustic signal.According to photoacoustic principle, particulate Absorptance be given by:

${\mathrm{\β}}_{abs}=\frac{P_m\·A_{res}\·{\mathrm{\π}}^2\·f_0}{P_L\·(\mathrm{\γ}-1)\·Q}cos({\mathrm{\φ}}_m-{\mathrm{\φ}}_L)---\left(3\right)$

Wherein P_mThe sound pressure signal recorded for mike, A_resFor the pond constant of photoacoustic cell, P_LOutput work for laser instrument Rate, the specific heat capacity of sample in γ photoacoustic cell, Q is the quality factor of photoacoustic cell, φ_m、φ_LIt is respectively photoacoustic signal, laser signal Phase place.

Sound pressure signal meets Lorentz distribution with the dependence of modulating frequency, it may be assumed that

${\tilde{P}}_m\left(f\right)=\frac{P_0}{\frac{2Q(f-f_0)}{f_0}+i}---\left(4\right)$

Wherein, P₀Being the amplitude of acoustic pressure at resonant frequency, i is imaginary number.Definition Transfer Formula is that acoustic pressure is at f₀Place amplitude with The ratio of the amplitude at f, i.e.

$\tilde{G}(f-f)\≡\frac{{\tilde{P}}_m\left(f_0\right)}{{\tilde{P}}_m\left(f\right)}---\left(5\right)$

Then:

$\tilde{G}\left(\right(f_0+df)-f_0)\≡\tilde{G}\left(df\right)\≡\frac{{\tilde{P}}_m\left(f_0\right)}{{\tilde{P}}_m(f_0+df)}=1-i\frac{2Q\·df}{f_0}---\left(6\right)$

Transfer FormulaAmplitude be:

$G\left(df\right)=\sqrt{1+{\left(\frac{2Q\·df}{f_0}\right)}^2}---\left(7\right)$

Phase place be:

${\mathrm{\φ}}_{G\left(df\right)}=-arctan\left(\frac{2Q\·df}{f_0}\right)---\left(8\right)$

Formula (6), (7), (8) are for f₀-df is equally applicable.

Understand according to formula (3):

$\begin{array}{c}{\mathrm{\β}}_{abs}\left(f\right)\∝\mathrm{Re}\[\frac{{\tilde{P}}_m\left(f\right)}{{\tilde{P}}_m\left(f\right)}\tilde{G}(f-f_0)\]=\mathrm{Re}\[\frac{P_m{e}^{{\mathrm{i\φ}}_m}}{P_L{e}^{{\mathrm{i\φ}}_L}}G(f-f_0)e^{{\mathrm{i\φ}}_G}\]\\ =\frac{P_m}{P_L}G(f-f_0)\cos ({\mathrm{\φ}}_m-{\mathrm{\φ}}_L+{\mathrm{\φ}}_G)\end{array}---\left(9\right)$

Therefore, for f₀The optoacoustic formula that at ± df, light absorbs is:

${\mathrm{\β}}_{abs}(f_0\±f)=\frac{P_m(f_0\±f)}{P_L(f_0\±f)}G\left(df\right)\frac{A_{res}}{\mathrm{\γ}-1}\frac{{\mathrm{\π}}^2{f}_0}{Q}cos({\mathrm{\φ}}_m-{\mathrm{\φ}}_L+{\mathrm{\φ}}_G)---\left(10\right)$

As df=0, β_absIt is f₀The computing formula at place.Utilize the method, the aerosol at three or multiple wavelength The absorption coefficient of light just can be measured in same photoacoustic cell simultaneously.

Advantages of the present invention

The present invention measures system relative to existing multi-wavelength aerosol absorptance, has the advantage that

The present invention utilizes a photoacoustic cell to measure aerosol absorption at multiple different wave lengths simultaneously, can avoid multiple The shortcomings such as systems bulky that photoacoustic cell causes, operating process are complicated.In addition, only need due to aerosol sample to flow through one Individual photoacoustic cell, it is not necessary to carry out the shunting of sample, therefore for each measurement wavelength, sample distribution over time and space is all Being uniform, be simultaneously achieved the system structure of employing, operating process is simple, and the spatial and temporal distributions of sample is uniform.Furthermore, this The LASER Light Source of bright middle use is all optical fiber output, and each wavelength light beam also carries out closing bundle through optical-fiber bundling device, therefore Avoiding the free light beam in space uses the optical glasss such as multiple reflecting mirror, light combination mirror to make during light path adjustment, light beam close bundle It is simple and compact that the light path complexity become and the increase of system bulk achieve light path

In a word, the invention provides a kind of method that real atmosphere aerosol component is carried out on-line analysis, based on Optoacoustic spectroscopy and Fourier number transform data processing method, utilize single photoacoustic cell on-line measurement atmospheric aerosol simultaneously to exist Optical absorption coefficient at multiple wavelength, calculates according to this measurement result and obtains aerocolloidal absorptionIndex, utilizes The aerocolloidal composition of this exponent pair is analyzed, thus tracing to the source and administering the decision-making foundation providing valuable for haze.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of the present invention.

Detailed description of the invention

As it is shown in figure 1, single photoacoustic cell measures the new method of aerosol multi-wavelength absorptance simultaneously, it is characterised in that: adopt Produce, with signal function generator 9, the square-wave signal that frequency interval is df, utilize these square-wave signals to multiple optical fiber lasers 1-3 carries out power magnitude modulation and produces different frequency laser signal, and these different frequency laser signals are by corresponding multiple optical fiber Laser instrument is changed into the Output of laser of corresponding different wave length, the Output of laser of different wave length by optical-fiber bundling device 4 carry out close bundle, Optical fiber adjusting pole 5 carries out vertical incidence photoacoustic cell 6 after light path adjustment, and ensures the axis coinciding of optical axis and photoacoustic cell, optoacoustic Pond 6 is provided with sample inlet and sample export, and in the Output of laser of different wave length and photoacoustic cell, aerosol interacts at optoacoustic Reaction gas sol particles absorption signal pressure wave signal is produced, simultaneously along original transmission direction injection photoacoustic cell, by putting in pond After photoacoustic cell rear end optical fiber adjusting pole 12 adjusts by, and accepted in real time by spectrogrph 13 and be converted into electric signal storage to arrive Computer 14 obtains different wave length and obtains laser signal for monitoring different wave length laser light signal, outside described photoacoustic cell 6 also Being provided with mike 7, described pressure wave signal receives conversion through mike 7, preamplifier 9 amplifies, lock-in amplifier 10 is believed Gathered by data collecting card 11 after number demodulation and carry out preserving the light obtaining reaction gas sol particles absorption signal at computer 14 Acoustical signal, computer combines different wave length and obtains laser signal and photoacoustic signal carries out data analysis and obtains aerosol at different ripples The absorptance of strong point.

Utilize single photoacoustic cell to measure aerosol its theoretical foundation of the new method of absorptance at multiple wavelength to be simultaneously:

Its operating frequency of instrument based on resonance type optoacoustic spectroscopy is the resonant frequency of photoacoustic cell, for single wavelength For, laser instrument is to carry out amplitude-modulated with this resonant frequency.But, for multi-wavelength system, need to measure many simultaneously Individual light absorbs the sound pressure signal produced.If all of acoustical signal all on resonant frequency, then the signal that mike records is just Being the superposition of all acoustic pressures, respective signal just cannot be distinguished by out.Therefore, exist utilizing single photoacoustic cell to measure aerosol simultaneously During absorptance at multiple wavelength, the resonant frequency f that laser amplitude modulating frequency is photoacoustic cell of one of them wavelength₀, its The laser amplitude modulating frequency of commplementary wave length is distributed in its vicinity.As a example by three wavelength systems, the Modulation and Amplitude Modulation of three wavelength lasers Frequency is respectively as follows: f₀、f₀+df、f₀-df.Mike is P to the response of the photoacoustic signal on resonant frequency_m(f₀), deviation resonance frequency The photoacoustic signal response of rate is P_m(f₀± df), the representative value of df is 5Hz, and this value is sufficiently large for the resolution of signal, and also The resonant frequency of the close resonant cavity that can try one's best is to realize effective enhancing of photoacoustic signal.According to photoacoustic principle, particulate Absorptance be given by:

${\mathrm{\β}}_{abs}=\frac{P_m\·A_{res}\·{\mathrm{\π}}^2\·f_0}{P_L\·(\mathrm{\γ}-1)\·Q}cos({\mathrm{\φ}}_m-{\mathrm{\φ}}_L)---\left(3\right)$

Wherein P_mThe sound pressure signal recorded for mike, A_resFor the pond constant of photoacoustic cell, P_LFor the output of laser instrument, The specific heat capacity of sample in γ photoacoustic cell, Q is the quality factor of photoacoustic cell, φ_m、φ_LIt is respectively photoacoustic signal, the phase of laser signal Position.

Sound pressure signal meets Lorentz distribution with the dependence of modulating frequency, it may be assumed that

${\tilde{P}}_m\left(f\right)=\frac{P_0}{\frac{2Q(f-f_0)}{f_0}+i}---\left(4\right)$

Wherein, P₀Being the amplitude of acoustic pressure at resonant frequency, i is imaginary number.Definition Transfer Formula is that acoustic pressure is at f₀Place amplitude with The ratio of the amplitude at f, i.e.

$\tilde{G}(f-f)\≡\frac{{\tilde{P}}_m\left(f_0\right)}{{\tilde{P}}_m\left(f\right)}---\left(5\right)$

Then:

$\tilde{G}\left(\right(f_0+df)-f_0)\≡\tilde{G}\left(df\right)\≡\frac{{\tilde{P}}_m\left(f_0\right)}{{\tilde{P}}_m(f_0+df)}=1-i\frac{2Q\·df}{f_0}---\left(6\right)$

Transfer FormulaAmplitude be:

$G\left(df\right)=\sqrt{1+{\left(\frac{2Q\·df}{f_0}\right)}^2}---\left(7\right)$

Phase place be:

${\mathrm{\φ}}_{G\left(df\right)}=-arctan\left(\frac{2Q\·df}{f_0}\right)---\left(8\right)$

Formula (6), (7), (8) are for f₀-df is equally applicable.

Understand according to formula (3):

$\begin{array}{c}{\mathrm{\β}}_{ads}\left(f\right)\∝\mathrm{Re}\[\frac{{\tilde{P}}_m\left(f\right)}{{\tilde{P}}_L\left(f\right)}\tilde{G}(f-f_0)\]=\mathrm{Re}\[\frac{P_m{e}^{{\mathrm{i\φ}}_m}}{P_L{e}^{{\mathrm{i\φ}}_L}}G(f-f_0)e^{{\mathrm{i\φ}}_G}\]\\ =\frac{P_m}{P_L}G(f-f_0)\cos ({\mathrm{\φ}}_m-{\mathrm{\φ}}_L+{\mathrm{\φ}}_G)\end{array}---\left(9\right)$

Therefore, for f₀The optoacoustic formula that at ± df, light absorbs is:

${\mathrm{\β}}_{abs}(f_0\±f)=\frac{P_m(f_0\±f)}{P_L(f_0\±f)}G\left(df\right)\frac{A_{res}}{\mathrm{\γ}-1}\frac{{\mathrm{\π}}^2{f}_0}{Q}cos({\mathrm{\φ}}_m-{\mathrm{\φ}}_L+{\mathrm{\φ}}_G)---\left(10\right)$

As df=0, β_absIt is f₀The computing formula at place.Utilize the method, the aerosol at three or multiple wavelength The absorption coefficient of light just can be measured in same photoacoustic cell simultaneously.

The system built based on laboratory during concrete operations of the present invention is carried out, and specifically includes following steps:

(1) the resonant frequency f of photoacoustic cell is measured₀, quality factor q and the pond constant A of photoacoustic cell_res, concrete measurement side Method is in " spectroscopy and spectrum analysis " the 9th phase of volume 28, and " near infrared band CO2 molecular relaxation mechanics effect is to optoacoustic for Li Jingsong The impact of signal " document has been described in detail；

(2) Transfer Formula is calculated according to the measurement result of step (1)Amplitude；

(3) by measuring the multiple-wavelength laser incoming fiber optic spectrogrph that aerosol absorbs, incidence merit at each wavelength is obtained Rate and the corresponding relation of spectrogrph signal amplitude, i.e. P_L(λ_i)∝P_S(λ_i), so, during reality is measured, it is possible to according to The changed power of the signal monitoring laser instrument of spectrogrph；

(4) connecting each instrument in measurement system according to Fig. 1, the frequency exported by functional generator is f₀、f₀+df、f₀- Df square-wave signal is respectively connected to the laser modulation interface of different wave length, the modulating frequency deviation resonance frequency of short wavelength laser Rate, the modulating frequency of long wavelength laser is near resonant frequency, to ensure that the measurement signal to noise ratio of each wavelength is in same level；

(5) by the output soft exchange light beam bundling device of different wave length laser instrument, fiber adjusting mount is adjusted so that incident optoacoustic The light beam in pond and the axis coinciding of photoacoustic cell；

(6) adjust the fiber adjusting mount after photoacoustic cell, receive the emergent light after photoacoustic cell, and the outgoing photoconduction that will receive Enter fiber spectrometer, it is achieved the monitoring of each wavelength laser power, i.e. P_L(λ₁)、P_L(λ₂)、P_L(λ₃)；

(7) by computer acquisition to photoacoustic signal carry out Fourier transformation, it is thus achieved that f₀、f₀+df、f₀Light at-df frequency Acoustical signal amplitude, i.e. P_m(f₀)、P_m(f₀+df)、P_m(f₀-df)；

(8) combine formula (10) according to the result of step (1) (2) (6) (7) and aerosol at each wavelength can be calculated Absorptance；

(9) combine formula (1) according to the measurement result of step (8) and can be calculated the AAC of atmospheric aerosol, and according to The size of this value judges aerocolloidal type.

Claims (5)

1. single photoacoustic cell measures the new method of aerosol multi-wavelength absorptance simultaneously, it is characterised in that: use signal function to send out It is the square-wave signal of df that raw device produces frequency interval, utilizes these square-wave signals that multiple optical fiber lasers are carried out power magnitude tune System produces different frequency laser signal, and these different frequency laser signals are changed into by corresponding multiple optical fiber lasers accordingly The Output of laser of different wave length, the Output of laser of different wave length by optical-fiber bundling device carry out close bundle, light path adjust after vertical incidence Photoacoustic cell, and ensure the axis coinciding of optical axis and photoacoustic cell, aerosol phase interaction in the Output of laser of different wave length and photoacoustic cell Reaction gas sol particles absorption signal pressure wave signal is produced, simultaneously along original transmission direction injection optoacoustic in being used in photoacoustic cell Pond, is accepted by spectrogrph and is converted into electric signal storage to monitor in real time to computer accomplished different wave length laser light signal, Mike it is additionally provided with outside described photoacoustic cell, described pressure wave signal receives conversion through mike, preamplifier amplifies, Gathered by data collecting card after the demodulation of lock-in amplifier signal and carry out preservation at computer and obtain reaction gas sol particles and absorb The photoacoustic signal of signal, computer combines different wave length and obtains laser signal and photoacoustic signal carries out data analysis and obtains aerosol Absorptance at different wave length.

2. single photoacoustic cell as claimed in claim 1 measures the new method of aerosol multi-wavelength absorptance simultaneously, and its feature exists Combine different wave length in: described computer and obtain laser signal and particulate absorption signal carries out data analysis and obtains gas Colloidal sol absorptance at different wave length is as follows:

(1) data, by data collecting card collected carry out Fourier transformation, obtain acoustical signal amplitude P at different frequency_m(f₀ ±f)；

(2), according to formula

It is calculated aerosol absorptance at different wave length；

Wherein f₀For the resonant frequency of photoacoustic cell, P_m(f₀± f) it is the sound pressure signal at the different frequency that records of mike, A_resFor The pond constant of photoacoustic cell, P_L(f₀± f) it is the output of each laser instrument, the specific heat capacity of sample in γ photoacoustic cell, Q is photoacoustic cell Quality factor, φ_m、φ_L、φ_GIt is respectively photoacoustic signal, laser signal and the phase place of transmission function G (df).

3. single photoacoustic cell as claimed in claim 1 measures the new method of aerosol multi-wavelength absorptance simultaneously, and its feature exists In: described spectrogrph is monitored different wave length laser light signal in real time and is referred to different wave length optical fiber laser is accessed spectrogrph, Obtain incident laser power P at each wavelength_L(λ_i) laser signal power magnitude P that arrives with spectrometer detection_S(λ_i) corresponding pass System, i.e. P_L(λ_i)∝P_S(λ_i), each optical fiber laser can be monitored according to the signal amplitude of spectrogrph during actual measurement Changed power.

4. single photoacoustic cell as claimed in claim 1 measures the new method of aerosol multi-wavelength absorptance simultaneously, and its feature exists In: described frequency interval is that the square-wave signal of df is arranged according to optical fiber laser number, it is possible to achieve at multiple wavelength, gas is molten The absorption coefficient of light of glue is measured simultaneously.

5. single photoacoustic cell as claimed in claim 4 measures the new method of aerosol multi-wavelength absorptance simultaneously, and its feature exists In: described multiple wavelength are 3 wavelength.