Raman Spectroscopy for On-Line Environmental and Atmospheric Analysis

Process Instruments, Inc.

Salt Lake City, UT

Process Instruments Inc. has developed a full-spectrum Raman scattering instrument, incorporating a multipass external cavity enhancement cell for gas phase analysis of Oxygen and Carbon Dioxide.

• Spectrograph Design: The Raman Specrograph design has reduced both size and weight of our Raman Spectrograph. In addition, to improving the signal collection by redesigning the optics placement.This improved design allows for increased signal collection, and improved signal resolution while maintaining a smaller foot print.
• Laser Lifetime and Improved Stability: Process Instruments Inc. has been able to improve the stability of our frequency-stabilized lasers by using a low AR (anti-reflective) coating on the front facet.This coating also allows for improved frequency tuning. Found a laser diode vendor that can supply Al-free laser diodes. Process Instruments in house life testing to date indicates that we can now warrant our lasers for at least one year. This is 4 times longer than any other similar laser manufacturers.

• A dual wavelength diode laser has been developed for use with one of upcoming MARS exploratory missions.The dual wavelength laser will allow a single spectrograph to measure the complete Raman spectra from ~300 cm-1 to ~4,000 cm-1. A NIR 785 nm laser is used for Raman scattering in the region of 300 to 2000 cm-1. Exciting with this wavelength reduces fluorescence problems. Exciting with a visible (670 nm) wavelength laser for the region of 2000 to 4000 cm-1 takes advantage of improved quantum efficiency.

• There has been considerable commercial interest from private companies to assist in Process Instruments Inc. Raman development. An arrangement has been structured to sell a basic instrument prototype in exchange for a company’s financing of our materials and development costs. Process Instruments Inc. acquired $468,000 in funds for basic diode-laser Raman instrumentation development.

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