ELECTRICALLY TUNABLE MICROMACHINED FABRY-PEROT-INTERFEROMETER IN GAS-ANALYSIS

This paper describes an optical gas concentration measurement system, which is based on an electrically tuneable micromachined Fabry-Perot i nterferometer (FPI). The operating principle of the system is NDIR Sin gle-Beam Dual-Wavelength measurement. The FPI is tuned so that the pas s band coincides with the absorption band of the measured gas; a detec tor records the strength of the signal getting through the measurement chamber. The pass band of the FPI is then shifted to either side of t he absorption band; the detected signal constitutes the reference sign al. The ratio of these two signals indicates the degree of light absor ption and so the gas concentration. Properties of the FPI are discusse d, as well as the performance of the measurement system.