FIBER OPTIC SENSOR FOR CHLORINATED HYDROCARBONS IN WATER-BASED ON INFRARED FIBERS AND TUNABLE DIODE-LASERS

A novel fiber optic evanescent wave spectroscopy (FEWS) system is base d on a tunable diode laser (TDL) source, on a polymer-coated AgClBr in frared transmitting fiber, and on a mercury cadmium telluride detector . This system was used for sensing low levels of chlorinated hydrocarb ons in water. The detection limit was 100 mug/l (100 ppb), which is an improvement by a factor of 50 in comparison to a similar system that is based on a Fourier transform infrared spectrometer, and the measure ment time was reduced by a factor of 3. The TDL-FEWS system shows sign ificant potential for in situ monitoring of ground water.