Gallium Arsenide Semiconductor-laser Multigas Analyzer (GASMAN)

The need exists for portable instrumentation with the capability of real-time monitoring of human environments for a variety of toxic gases generated by military weapons systems. Spectral Sciences, Inc. (SSI) proposes to build a Gallium Arsenide Semiconductor-laser Multigas Analyzer (GASMAN) which will provide automatic, unattended, real-time monitoring of several toxic gases. GASMAN employs multiple diode-laser in conjunction with multiplexing techniques to simultaneously monitor air samples for fimve or more toxic species in a common flow-through sampling cell. GASMAN uses techniques of wavelength modulation and line-locked absorption detection common to several gallium arsenide-based snesors developed by SSI for automated and unattended operation in the detection of single species in open air. GASMAN incorporates these features, along with a long-path absorption cell, multiple diode-laser sources, and multiplexing techniques. An internal microprocessor system controls experimental sequencing and stores several hours of continuous concentration data with sub-second time resolution. The resulting system is portable, compact, lighweight, and has low power consumption requirements. The objective of this work is to develop a prototype system for deployment in military applications. Phase I will demonstrate the feasibility of the GASMAN approach b y monitoring representative toxic gases using a breadboard incorporating three basic elements; line-locked detection, a multiple-pass absorption cell, and multiplexced laser-diodes. Phase Ii development will lead to a working prototype.