Near-infrared absorption spectra of NO, N02, and N20 were observed in the wavelength region between 1.2 and 1.9 ii m using a high-resolution Fourier-transform spectrometer, and we have obtained precise absorption data which are useful for Tunable Diode Laser Absorption Spectroscopy (TDLAS).Furthermore, the NO and N2O were detected by means of TDLAS method for the first time using InGaAs-DFB diode lasers which were designed to access absorption lines at wavelengths of 1.798 and 1.766 /2 m, respectively.

A technique for simultaneous detection of oxygen molecules and soot particles by means of visible tunable diode laser absorption spectroscopy (TDLAS) was investigated. The effects of solid particles on the measurement of oxygen molecules were evaluated using a 7GOnm visible diode laser. The maximum solid particle density was 5.6g/m3m, allowing measurement of the concentration of oxygen with sufficient precision.We applied this technique to analysis of real exhaust gas from a large-scale test furnace, and verified that oxygen molecules and soot particles in such gas can be directly measured from a large-scale test plant without pretreatment, such as removal of water vapor and soot.