WATER-CORE WAVE-GUIDE FOR POLLUTION MEASUREMENTS IN THE DEEP-ULTRAVIOLET

A fiber optic system for water analysis with high transparency in the deep-UV region (lambda greater than or equal to 190 nm) is presented. The system consists of special UV-improved silica fibers and a liquid- core waveguide (LCW) as an optical cell. The apertures of both light g uides, the silica fiber and the LCW, are matched. The optical losses o f the device are investigated experimentally and compared with theory, especially with a standard free-space geometry. The performance of th e system with respect to UV absorption spectroscopy is demonstrated fo r nitrate and chlorine pollution in pure water. For a 203-mm-long LCW the detection limits have been determined to be as low as 22 mu g/L fo r nitrate and 26 mu g/L for chlorine. (C) 1998 Optical Society of Amer ica.