[15p-P1-1~9] 1.5 Instrumentation, measurement and Metrology

[15p-P1-3] Near infrared spectra of trace moisture in N₂ using dual-laser cavity ring-down spectroscopy

〇Hisashi Abe¹, Koji Hashiguchi¹ (1.NMIJ/AIST)

Keywords:Humidity standard

We developed a measurement system for trace moisture using CRDS with two diode lasers (laser1 and laser2). The two lasers were connected to an optical switch using optical fibers, and the output laser light from the optical switch was introduced to a ring-down cavity. The ring-down cavity was filled with a standard gas mixture of trace moisture in N₂ generated using the NMIJ magnetic suspension balance/diffusion-tube humidity generator. The frequency of the laser1 was controlled to the peak position of a water absorption line and that of the laser2 was to an off-peak position (baseline). The laser1 and laser2 were used to measure the moisture content and correct the baseline drift, respectively.