[A mobile sensor for remote detection of natural gas leakage].

The detection of natural gas pipeline leak becomes a significant issue for body security, environmental protection and security of state property. However, the leak detection is difficult, because of the pipeline's covering many areas, operating conditions and complicated environment. A mobile sensor for remote detection of natural gas leakage based on scanning wavelength differential absorption spectroscopy (SWDAS) is introduced.

[Study of remote sensing the flux of carbon dioxide gas with tunable diode laser absorption spectroscopy].

Tunable diode laser absorption spectroscopy (TDLAS) technique is a new method to detect trace gas qualitatively or quantificationally based on the scan characteristic of the diode laser to obtain the absorption spectra in the characteristic absorption region. TDLAS is a highly sensitive, highly selective and fast time response trace gas detection technique. In the present paper, a DFB laser at room temperature was used as the light source, wavelength modulation method was employed, and the second harmonic signal of one absorption line near 1.

[Monitoring the flux of carbon dioxide gas with tunable diode laser absorption spectroscopy].

The greenhouse effect exacerbated by the increase of Carbon-containing gases is the more important causes of the climate change, It is very meaningful to the large-scale flux of carbon dioxide detection for the estimate the contributions of the main greenhouse gases in the atmosphere of various errestrial eco-systems. Tunable diode laser absorption spectroscopy (TDLAS) is a highly sensitive, highly selective and fast time response trace gas detection technique. In the present paper, the authors used a DFB laser was used as the light source, and by employing wavelength modulation method, and measuring the second harmonic signal of one absorption line near 1.

[An investigation of temperature compensation of HCL gas online monitoring based on TDLAS method].

HCL, with the character of strong erosion and toxicity, is a kind of chemical material of vital importance. So measuring the HCL in-situ can not only optimize its production process, but also be necessary to reduce the environment pollution. TDLAS (tunable diode laser absorption spectroscopy) technology, and owning the advantage of the tunability and narrow line width of the diode laser, this method can relatively easily select the absorption line of the detected gas without the interference from other gas, thus making the rapid and accurate HCL measurement possible.

[System design of open-path natural gas leakage detection based on Fresnel lens].

Based on the technology of tunable diode laser absorption spectroscopy (TDLAS) in conjunction with second harmonic wave detection, a long open-path TDLAS system using a 1.65 microm InGaAsP distributed feedback laser was developed, which is used for detecting pipeline leakage. In this system, a high cost performance Fresnel lens is used as the receiving optical system, which receives the laser-beam reflected by a solid corner cube reflector, and focuses the receiving laser-beam to the InGaAs detector.

[Monitoring the change in CO concentration in combustion with tunable diode laser absorption spectroscopy].

In the present paper, the technology of tunable diode laser absorption spectroscopy (TDLAS) in conjunction with the open path multi-pass Herriot cell and the new-style detection method of auto-balanced detection combined with wavelength modulation technology were used, and the concentration of CO produced in combustion of alcohol blowtorch was measured. It was found in the measured result that the change in CO concentration in the flame of alcohol blowtorch presented a stated periodicity in the process of combustion and the average concentration of CO was calculated to be 49.4 (10(-6) ratio by volume).