Jiuying Chen

H2S detection by tunable diode laser absorption spectroscopy

Hydrogen Sulfide is a highly toxic and flammable gas. It is generated as a common by-product of many industrial processes. Early detection of H2S at concentrations of 10 ppm in air is essential to prevent its toxic influence at higher concentrations. Tunable diode Laser based gas detectors are now being used in a wide variety of applications for safety and environmental interest. Their characteristics like non-intrusive, high selectivity, high sensitivity, and fast response time make them more appealing than conventional point sensors for a reliable H2S detection. A long open-path H2S sensor based on tunable diode laser absorption spectroscopy has been developed, using telecommunication near infrared distributed feed-back(DFB) tunable diode laser combining with wavelength modulation spectroscopy technology, a detection limit of 20 ppmldrm has been demonstrated, an on-board reference cell provides on-line sensor calibration. The sensor is very suitable for large area field H2S monitoring application.

Comparison and research of group refractivity models and atmospheric delay to lidar

Satellite laser range system measures the distance between the satellite and the surface of the earth by figuring out the transit time of laser pulse. The beam is refracted when it goes through the atmosphere. The atmosphere refraction effect causes laser propagation delay and path bending, which is one of the key factors to restrict the accuracy of laser ranging. In order to improve the accuracy of atmospheric refraction delay correction, it is necessary to strengthen the study of atmospheric group refractivity models and atmospheric refraction delay correction method. According to the data of Xuzhou upper air meteorological station, which are the monthly values of upper limit layers for 30 years (1981-2010) in China, three atmospheric group refractivity models were analyzed and compared. The atmospheric refraction delays to LiDAR were calculated by ray tracing method. The differences among the group refractivity models as a function of month or direction angle were given, which lay the foundation for the practical application and precision evaluation of LiDAR.

The development of the infrared technology for meteorological satellites in Shanghai Institute of Technical Physics

The requirement of the infrared technology applied on meteorological satellites is the key driving force for the development of infrared technology in Shanghai institute of technical physics (SITP), Chinese Academy of Sciences. The meteorological satellites have become a main detection method for the weather and ocean observation, there are totally 15 meteorological satellites that were launched into both sun synchronous and geostationary orbit and more satellites are under construction to be the second generation ones. The infrared remote sensors are the main payloads on-board on all these satellites. By these infrared remote sensors one can obtain the remote sensing data for ocean colour, water vapour, weather forecasting, and get the atmospheric temperature profile and humidity profile, etc. As the key technology in the infrared remote sensor, the infrared detector technology is developed mainly using the HgCdTe material, meanwhile the quantum well infrared photodetector and type II super-lattice infrared detector are also developed.

Experimental study on mutual broadening coefficient between CO2 and CO and its temperature dependence coefficient under high temperature

A diode laser sensor based on absorption spectroscopy has been developed for the measurement of spectroscopic parameters of the R(50) line at 5007.787cm-1 (20012<-00001 band) of CO2. Survey spectra of the CO2 R(50) line of CO2 - CO mixture gas with 49.82% CO2 were recorded at different temperatures and pressures through a high temperature measurement system using tunable diode laser absorption spectroscopy. High-resolution measurements of the CO2 R(50) line shape were used to determine collisional broadening full-width of CO2 by CO as a function of pressure and temperature. The collisional broadening coefficients were obtained at temperatures between 323K and 1873K, and the temperature dependent coefficient of the collisional broadening full-width of CO2 by CO was calculated. These parameters are supplement and improvement to the existing database. They are helpful for the detection of CO2 concentration in combustion diagnosis to ensure the accurate inversion of CO2 concentration in the combustion process.