CN103048284A - Novel method for measuring extinction coefficient of atmospheric aerosol - Google Patents

Abstract

The invention relates to a novel method for measuring the extinction coefficient of atmospheric aerosol. According to the method, a film plated glass pipe, a laser light source, an optical system and a data collection system are included, wherein light has long transmission light path and low loss in the film plated glass pipe, light of a certain wavelength makes long-distance transmission with a certain angle between pipe walls in the glass pipe filled with aerosol, the attenuation information of light by aerosol can be measured through probes at two ends of the glass pipe, and multiple reflections of light in the glass pipe greatly improves the extinction sensitivity of aerosol. The invention sets up the measurement formula of the extinction coefficient of a wave of multi-wavelength, and the relative calculation method based on the ratio avoids the measurement error caused by light intensity fluctuation during photoelectric conversion; and the novel method has the characteristics of simple principle, convenience in operation and fastness in detection speed.

Description

Utilize the coated glass pipe to measure the new method of Aerosol Extinction Coefficients

Technical field

The present invention relates to the Aerosol Extinction fields of measurement, be specifically related to a kind of new method of direct measurement Aerosol Extinction Coefficients, it can measure the Aerosol Extinction Coefficients of a plurality of wavelength in real time.

Background technology

Atmospheric aerosol is the important component part of atmosphere, it is a key factor in the atmospheric physics chemical process, atmospheric aerosol has important directly and indirectly affecting to climate change, absorbs and diffusesolarradiation by particulate, directly changes the energy budget of ground-gas system.Be based upon on the atmosphere light scattering basis, measure the particularly extinction coefficient on the different wave length and set up the wavelength transformational relation of aerosol optical characteristics, can deepen the understanding to aerosol optical characteristics, expand the radiation delivery research of laser in atmosphere, assess more accurately Radiative Forcing and the climate effect of atmospheric aerosol, have important academic significance and potential using value.

The method of measuring Aerosol Extinction can be divided into following several substantially, 1, the forward detection method: an end is the Emission Lasers light source initiatively, (other end of 50m ~ 2000m) is accepted transmitted light on certain distance, the ratio of transmitted light and incident light is exactly transmitance and then is converted into extinction coefficient, 2 backward probe methods: laser radar etc. belong to the active probe method, measure aerocolloidal backscatter signal inverting and obtain extinction coefficient, 3 side direction probe methods: visiometer is measured probe method exactly, measure aerocolloidal side direction (33 °) scattered signal inverting and obtain extinction coefficient, 4 reflectometrys: also can the inverting extinction coefficient to the contrast of natural reflection of light and peripheral object by jobbie.Above these methods have certain limitation, for example: the forward detection method needs certain measuring distance (light path), and backward and side direction and reflectometry all are the methods of inversion, are not direct measurements, and above-mentioned method generally all is to measure the extinction coefficient of a certain wavelength in addition.Extinction coefficient on a lot of wavelength also can only obtain in the profiling type derivation ^[7], therefore studying the extinction coefficient of gasoloid on different wave length is highly significant.

Utilize the coated glass pipe to measure the new method of Aerosol Extinction Coefficients, overcome the shortcoming of said method, the method that it adopts direct forward direction to measure, in one meter long glass tube, can realize tens meters light transmission, reach the purpose of long-range transmission, reflected truly that light transmits in atmosphere and with aerocolloidal interaction.Use semiconductor laser as the incident light light source, the optional 532nm of wavelength, 635 nm, 650 nm, 660 nm, 808 nm and 980 nm, as long as the wavelength that has on the market can be selected, also can be continuous laser source, these advantages will be expanded aerocolloidal delustring research and application thereof greatly.

Summary of the invention

The object of the invention is to the deficiency for existing Aerosol Extinction Coefficients measuring technique, provide that a kind of structure is ingenious, precision is high and the new method of real-time measurement.The method can effectively be measured the Aerosol Extinction Coefficients on the multi-wavelength; The method has that principle is simple, easy to operate, the detection sensitivity high.

The technical solution used in the present invention is:

Utilize the coated glass pipe to measure the new method of Aerosol Extinction Coefficients, it is characterized in that: comprise glass tube, described glass tube inside and outside wall is coated with highly reflecting films, be provided with the gasoloid entrance, outlet and beam inlet, outlet, described gasoloid entrance, outlet lays respectively at the two ends of glass tube and all perpendicular to glass tube, the gasoloid entrance is provided with air valve, the gasoloid outlet is provided with aspiration pump, described beam inlet, outlet lays respectively at the two ends of glass tube and equal angles angled with glass tube, beam inlet is provided with the laser diode of a plurality of wavelength as light source, light path between laser diode and the beam inlet is provided with parallel light tube, spectroscope, the light beam that laser diode is launched makes beam collimation through parallel light tube, produce the identical collimated light beam of two light beams quality by spectroscope again, conduct is with reference to light and incident light respectively, the whole energy of described reference light enter photodetector one, be converted into corresponding electric signal, beam outlet is provided with photodetector two, described incident light reflects the laggard photodetector two that enters in glass tube, photodetector one, the single-chip microcomputer of the electrical signal access AD converter of photodetector two, single-chip microcomputer is the control linkage laser diode also, air valve, aspiration pump, single-chip microcomputer connects computing machine by the USB interface that connects; Concrete measuring process may further comprise the steps:

(1) loads onto filtrator at the gasoloid entrance of glass tube, allow the wavelength be that the incident light of λ enters glass tube at an angle, by there not being aerocolloidal clean propagation in atmosphere, and incident light electric signal without the aerosol particle period of the day from 11 p.m. to 1 a.m in glass tube that recording light electric explorer two detects is i ₂(λ), the while wavelength is that the reference light of λ directly enters photodetector one, and electric signal corresponding to wavelength X that recording light electric explorer one detects is i ₁(λ);

(2) take away the filtrator of the gasoloid entrance of glass tube, allow gasoloid evenly enter in the glass tube, open the aspiration pump of the gasoloid outlet of glass tube, bleed with aspiration pump and to make particulate Uniform Flow in glass tube, allow the wavelength be that the incident light of λ enters glass tube at an angle, pass atmospheric aerosol to be measured, the scattered light light intensity of particulate is faint, consume through glass tube inwall reflection quilt, the absorption of particulate is converted into molecular thermalmotion, arrival photodetector two is converted into corresponding electric signal to incident light by the particulate scattering with after absorbing, and the electric signal that record photodetector this moment two detects is i ₃(λ);

(3) in step (1), (2), the electric signal that detects in photodetector one, the photodetector two is separately converted to digital signal and through accessing computing machine after the single-chip microcomputer processing, computer-internal software has been set up the Aerosol Extinction measure equation of different wave length:

${\mathrm{\β}}_{\mathrm{ext}\left(\mathrm{\λ}\right)}=-\ln \left(\frac{i_2\left(\mathrm{\λ}\right)-i_3\left(\mathrm{\λ}\right)}{i_1\left(\mathrm{\λ}\right)}\right)/D$

Wherein D is the light path of light in the glass tube;

Thus, calculating gasoloid is extinction coefficient β on the λ at wavelength _{Ext (λ)}

Principle of the present invention is:

Measuring system is comprised of utilizing emitted light unit, coated glass pipe, two photodetection unit and control and signal processing unit.Adopt the glass tube of inside surface and outside surface plating high reflection film as optical transmission tube, numerical evaluation is in conjunction with the method for laboratory measurement, and the internal diameter of establishing glass tube is d, and the length of glass tube is L, and beam incident angle is, obviously has:

Light beam number of turns N:

$N=\frac{L}{\mathrm{tg\θ}\·d}$

Stroke P between per two secondary reflections of light in glass tube is:

P=tgθ·d

The total transmission range of light beam in gasoloid:

$D=\frac{L}{\sin \mathrm{\θ}}$

Can see, transmission range and glass tube internal diameter size are irrelevant, only relevant with glass tube length and incident angle.If with 1 ° incident angle, will make light transmission range in the gasoloid medium amplify 57.3 times than directly measuring, greatly improved the sensitivity that Aerosol Extinction is measured.Certainly, also the factor such as relevant with the reflectivity size of detector sensitivity, bore size size, light beam input aperture, glass tube inwall is relevant for minimum incident angle.The length of this device glass tube is got 860 millimeters, and 30 millimeters of diameters, incident angle of light are got 1 degree, and light transmits nearly 50 meters.

Adopt the mode of signal comparison to avoid glass tube tube wall and atmospheric molecule to the impact of signal, at air intake opening filtrator is housed, what do not have measuring-signal light in the aerocolloidal situation in glass tube sees through information Ext ₂, then take away filtrator, allow gasoloid evenly enter in the glass tube, measuring-signal light sees through information Ext again ₃If incident intensity is Ext ₁, this moment, aerocolloidal dampening information can be expressed as Ext _a=(Ext ₂-Ext ₃)/Ext ₁

Advantage of the present invention and beneficial effect are:

1, in site measurement has kept light and atmospheric aerosol particle objectively to interact;

2, measuring principle is directly simple, designs ingeniously, easy to operate, and detection sensitivity is high, and detection speed is fast;

3, the ratio compute mode has been eliminated in the opto-electronic conversion light-intensity variation for the impact of measurement result;

4, realize the long-range transmission of light in limited distance.

The present invention utilizes the coated glass pipe to measure the measuring method of Aerosol Extinction Coefficients, in the coated glass pipe, transmit the characteristics such as optical length, loss be low based on light, the light of a certain wavelength long Distance Transmission between tube wall at a certain angle in being full of aerocolloidal glass tube, gasoloid can obtain by the detector measurement of glass pipe end the dampening information of light, and light repeatedly turning back in glass tube improved the sensitivity of gasoloid decay greatly; Measuring method of the present invention does not change the suspended state of particle in measuring process, effectively deducted the interference of tube wall and air molecule light scattering in the measurement, can carry out continuous real-time online measuring to atmospheric aerosol, quantification monitoring for meteorological environmental administration, for studying aerocolloidal microphysical property, all showed good application prospect.

Description of drawings

Fig. 1 is the instrumentation plan of extinction coefficient of the present invention.

Embodiment

As shown in Figure 1, utilize the coated glass pipe to measure the new method of Aerosol Extinction Coefficients, include glass tube 1, glass tube 1 inside and outside wall is coated with highly reflecting films, being provided with gasoloid enters, outlet 2,3 and light beam enter, outlet 4,5, gasoloid enters, outlet 2,3 lay respectively at the two ends of glass tube 1 and all perpendicular to glass tube 1, gasoloid entrance 2 is provided with air valve 6, gasoloid outlet 3 is provided with aspiration pump 7, light beam enters, outlet 4,5 lay respectively at the two ends of glass tube 1 and equal angles angled with glass tube, beam inlet 4 is provided with the laser diode 8 of a plurality of wavelength as light source, light path between laser diode 8 and the beam inlet 4 is provided with parallel light tube, spectroscope 9, the light beam that laser diode 8 is launched makes beam collimation through parallel light tube, produce the identical collimated light beam of two light beams quality by spectroscope 9 again, conduct is with reference to light and incident light respectively, the whole energy of reference light enter photodetector 1, be converted into corresponding electric signal, beam outlet 5 is provided with photodetector 2 11, incident light reflects the laggard photodetector 2 11 that enters in glass tube 1, photodetector 1, the single-chip microcomputer 12 of the electrical signal access AD converter of photodetector 2 11, single-chip microcomputer 12 is control linkage laser diode 8 also, air valve 6, aspiration pump 7, single-chip microcomputer 12 connects computing machine 13 by the USB interface that connects; Concrete measuring process may further comprise the steps:

(1) loads onto filtrator 14 at the gasoloid entrance 2 of glass tube 1, allow the wavelength be that the incident light of λ enters glass tube 1 at an angle, by there not being aerocolloidal clean propagation in atmosphere, and incident light electric signal without the aerosol particle period of the day from 11 p.m. to 1 a.m in glass tube 1 that recording light electric explorer 2 11 detects is i ₂(λ), the while wavelength is that the reference light of λ directly enters photodetector 1, and electric signal corresponding to wavelength X that recording light electric explorer 1 detects is i ₁(λ);

(2) take away the filtrator 14 of the gasoloid entrance of glass tube 1, allow gasoloid evenly enter in the glass tube 1, and the aspiration pump 7 of the gasoloid outlet of unlatching glass tube 1, bleed with aspiration pump 7 and to make particulate at glass tube 1 interior Uniform Flow, allow the wavelength be that the incident light of λ enters glass tube 1 at an angle, pass atmospheric aerosol to be measured, the scattered light light intensity of particulate is faint, consume through glass tube 1 inwall reflection quilt, the absorption of particulate is converted into molecular thermalmotion, arrival photodetector 2 11 is converted into corresponding electric signal to incident light by the particulate scattering with after absorbing, and the electric signal that record photodetector this moment 2 11 detects is i ₃(λ);

(3) in step (1), (2), the electric signal that detects in photodetector 1, the photodetector 2 11 is separately converted to digital signal and through access computing machine 13 after single-chip microcomputer 12 processing, computing machine 13 in house softwares have been set up the Aerosol Extinction measure equation of different wave length:

${\mathrm{\β}}_{\mathrm{ext}\left(\mathrm{\λ}\right)}=-\ln \left(\frac{i_2\left(\mathrm{\λ}\right)-i_3\left(\mathrm{\λ}\right)}{i_1\left(\mathrm{\λ}\right)}\right)/D$

Wherein D is the light path of light in the glass tube;

Thus, calculating gasoloid is extinction coefficient β on the λ at wavelength _{Ext (λ)}

Claims (1)

1. utilize the coated glass pipe to measure the new method of Aerosol Extinction Coefficients, it is characterized in that: comprise glass tube, described glass tube inside and outside wall is coated with highly reflecting films, be provided with the gasoloid entrance, outlet and beam inlet, outlet, described gasoloid enters, outlet lays respectively at the two ends of glass tube and all perpendicular to glass tube, the gasoloid entrance is provided with air valve, the gasoloid outlet is provided with aspiration pump, described light beam enters, outlet lays respectively at the two ends of glass tube and equal angles angled with glass tube, beam inlet is provided with the laser diode of a plurality of wavelength as light source, light path between laser diode and the beam inlet is provided with parallel light tube, spectroscope, the light beam that laser diode is launched makes beam collimation through parallel light tube, produce the identical collimated light beam of two light beams quality by spectroscope again, conduct is with reference to light and incident light respectively, the whole energy of described reference light enter photodetector one, be converted into corresponding electric signal, beam outlet is provided with photodetector two, described incident light reflects the laggard photodetector two that enters in glass tube, photodetector one, the single-chip microcomputer of the electrical signal access AD converter of photodetector two, single-chip microcomputer is the control linkage laser diode also, air valve, aspiration pump, single-chip microcomputer connects computing machine by the USB interface that connects; Concrete measuring process may further comprise the steps:

(1) loads onto filtrator at the gasoloid entrance of glass tube, allow the wavelength be that the incident light of λ enters glass tube at an angle, by there not being aerocolloidal clean propagation in atmosphere, and incident light electric signal without the aerosol particle period of the day from 11 p.m. to 1 a.m in glass tube that recording light electric explorer two detects is i ₂(λ), the while wavelength is that the reference light of λ directly enters photodetector one, and electric signal corresponding to wavelength X that recording light electric explorer one detects is i ₁(λ);

(2) take away the filtrator of the gasoloid entrance of glass tube, allow gasoloid evenly enter in the glass tube, open the aspiration pump of the gasoloid outlet of glass tube, bleed with aspiration pump and to make particulate Uniform Flow in glass tube, allow the wavelength be that the incident light of λ enters glass tube at an angle, pass atmospheric aerosol to be measured, the scattered light light intensity of particulate is faint, consume through glass tube inwall reflection quilt, the absorption of particulate is converted into molecular thermalmotion, arrival photodetector two is converted into corresponding electric signal to incident light by the particulate scattering with after absorbing, and the electric signal that record photodetector this moment two detects is i ₃(λ);

(3) in step (1), (2), the electric signal that detects in photodetector one, the photodetector two is separately converted to digital signal and through accessing computing machine after the single-chip microcomputer processing, computer-internal software has been set up the Aerosol Extinction measure equation of different wave length:

${\mathrm{\β}}_{\mathrm{ext}\left(\mathrm{\λ}\right)}=-\ln \left(\frac{i_2\left(\mathrm{\λ}\right)-i_3\left(\mathrm{\λ}\right)}{i_1\left(\mathrm{\λ}\right)}\right)/D$

Wherein D is the light path of light in the glass tube;

Thus, calculating gasoloid is extinction coefficient β on the λ at wavelength _{Ext (λ)}

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