マイクロマシン技術を用いた小型光学式マルチガスセンサ [II]:—ラマン散乱型と紫外吸収分光型ガスセンサの特性—

概要

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Compact optical gas sensors based on the Raman effect and ultraviolet absorption spectroscopy were developed. These sensors are miniaturized and do not require alignment, because the mirrors and optics are fixed onto a precisely machined micro optical bench made by micromachining technology. The Raman type gas sensor consists of a small DPSS laser (wavelength 532 nm, pulse energy 200 µJ, pulse width 3 ns, repetition frequency 1 kHz), the sensor chip, and the detector, which are connected by optical fibers. The UV absorption type gas sensor is consists of a D2 lamp, the sensor chip and a compact spectrometer, which are connected by optical fibers. The measured signals showed good linearity along with the gas concentrations. The limit of detection using the Raman effect was 1% for hydrogen or 0.2% for methane, and the minimum limit of detection using ultraviolet absorption spectroscopy was 10 ppm for ammonia and sulfur dioxide for an optical path length of 20 mm.