SOME APPLICATIONS OF NIR TUNABLE DIODES FOR REMOTE-SENSING

Three versions of a near infrared system based on commercial communica tion type laser diodes have been developed. They have high selectivity and good sensitivity for a number of important gases. All three syste ms use a common control and data logging and analysis box. The LASAIR- R is a simple, inexpensive, remote sensing instrument using a single 1 0 cm Cassegrain telescope to both transmit and receive the laser beam. The LASAIR-S is a system for continuous, non-extractive stack monitor ing. Fibre optics are used to take the laser beam from the control box (suitably located in the plant), to the stack and to return the absor bed beam. The LASAIR-P is a point source instrument using a multipath cell inside the box to provide the sensitivity required. The ease of o peration and the relatively low cost should make these systems an attr active method for measuring specific gases for industrial and regulato ry markets as well as for specific scientific measurements.