Diode Laser Raman Scattering Prototype for Gas Phase Environmental Monitoring

Period of Performance: 02/14/1997 - 05/14/1999


Phase 2 SBIR

Recipient Firm

Process Instruments, Inc.
825 North, 300 West, Suite 225
Salt Lake City, UT 84103
Principal Investigator

Research Topics


We propose to develop a diode-laser-based, full-spectrum Raman scattering instrument incorporating a multipass, external cavity enhancement cell for full spectrum, gas phase analysis of environmental pollutants. Narrow, well-defined Raman peaks and insensitivity to moisture contamination allow for full-spectrum detection with better than 1 ppm sensitvity in less than 60 seconds. Conventional Raman instrumentation is too expensive and not sensitive enough for industrial applications. For excitation of Raman scattering Ar ion lasers have too short of a life and are too expensive for continuous use. Semicondcutor laser diodes offer longer life than conventional lasers and now have sufficient power for rapidly obtaining Raman signals at ppm levels. Traditionally environmental instrumentation requires hot stack gases to be cooled prior to being measured. Cooling stack gas results in condensation and loss of water soluble species. Raman's ability to measure gas samples at high temperatures (>200 degress C) ensures that stack gas emissions can be measured completely and accurately. Phase II is a product development plan to build a rugged, reliable and cost effective instrument including an efficient volume holographic spectrometer, multipass external cavity enhancement cell, application specific software, user interface, calibration procedures and appropraite packaging. The prototype will be tested on-line in industrial environmental monitoring applications.