High resolution, high sensitivity gas analyzer using a wide-band tunable CO_2 laser

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Characteristics of the material peculiar absorption wavelength may be utilized for the measuring method of types and concentration such as the pollutant which exists in the atmosphere. Wide-band tunable CO2 laser and high-resolution absorption cell are required when this method is utilized.An experimental analytical equipment system was constructed, The system consists of four componennts.The first one is a wideband tunable CO_2 laser by combining a waveguide CO_2 laser with CdTe traveling wave wideband electrooptic phase modulator. A single frequency line selectable C0_2 laser and a wide-bannd electrooptic travelingwave phase modulator were constructed.The modulator has been composed of the CdTe modultion element (2mmx2mmxl5mm) divided in five in order to enable the wide-bannd modulator. It is possible that the modulator composed of divided modulation element achieves the wide-band modulation by adjusting the phase of microwaves between sections . The microwave transmission characteristics bandwidth of the modulator was 10GHz for one element.The second one is a high resoluble, high sensitive gas absorption cell. High resoluble high sensitive gas absorption cell which inserted the white mirror (mirror interval 2Ocm, mirror reflectivity 99.7%) in the Fabry-Perot interferometer (mirror interval 6Ocm, mirror reflectivity 98%) was constructed and tested, and 1MHz resolution was obtained.The last one is an JR HgCdTe photodetector and a storage oscilloscope.