[Study on the Spiral-Torus Herriott Type Cell].

With the rapid development of social economy, the environmental pollution and the ecological destruction are continuously deteriorating while sudden environmental pollution incidents occur frequently. Real-time monitoring harmful gases of the air take advantages of spectroscopic techniques for concentration measurement. Multipass optical cells are -widely used in absorption spectrometry technique to improve gas detection sensitivity under the condition of weak absorption. This paper proposes a spiral-torus type multipass optical device base on the structure of Herriott type cell. The optical device consists of multiple torus concave mirrors in a spiral way. Incident light propagates along with radical and axial direction in winding staircase pattern. The faculae on the inner wall present a spiral-type. The entrance and exit apertures are separated due to the spiral trace of optical rays, which increases the accessible adjustment of the apparatus. The effective optical length can be adjusted based on the proportional relationship to the reflective times. This device is characterized with easy adjustment and excellent mechanical performance due to its cylindrical structure. Based on ABCD matrix, the stability of the system was analyzed and the relationship between the number of reflections and the incident angle were discussed. With optical simulation software, we designed a device for separating polarized light, and the characteristics of its rotation was studied.

[Design of inhalable particulate matters measurement based on the Mie scattering extinction].

The concentration of inhalable particle is an important indicator in atmospheric environment monitor. Based on Mie scattering extinction, a precise testing instrument which can measure the concentration of inhalable particles at the atmospheric was designed by three-wavelength method in combination with the algorithm of distributed function. The dependence of extinction index on the spectrum was calculated based on Mie scattering theory in this article. Furthermore, the signal of time domain is integrated in the data processing to reduce the effect of error caused by multi-peak of spectra. The PM2.5 and PM10 were collected simultaneously in particle selection. Three different wave-lengths of lasers were coupled into an optical fiber by coupler (3 in 1) and passed through the sample cell. The attenuated light was detected by a PIN. Output of the detector was converted, amplified, displayed and stored by electronic system. Finally, the data were transmitted and shared in network through the 3G wireless module. The average particle size and concentration of inhalable particles were measured by this device at the same time. The technical specifications of the detector were verified by experiment, the experimental results indicate that the detection sensitivity of the system is 0.01 microg m(-3), the responsive time of system is approximately 90 s and it is suitable for measuring particulate matter concentrations of atmosphere.