Development of a compact, handheld Raman instrument with no moving parts for use in field analysis

This article describes a lightweight, self-contained, field portable Raman instrument that has been developed for rapid on-site determination of prima ry mixture components. The instrument consists of a helium neon (HeNe) lase r for excitation, an acousto-optic tunable filter (AOTF) for wavelength dis crimination, and an avalanche photodiode for detection. The AOTF is the pri mary component of this system and has been selected based on its spectral r ange (600-900 nm) along with its high resolution, similar to 7.5 cm(-1). La bview(TM) based software for controlling the AOTF frequency and the signal acquisition has also been developed. Several different samples were analyze d (both solids and liquids) using this instrument for the evaluation of par ameters such as spectral resolution, sensitivity, and data acquisition spee d for certain environmentally important compounds. The results from these m easurements are compared with those using a conventional laboratory Raman s ystem consisting of a grating-based spectrograph and a charge-coupled devic e. (C) 2000 American Institute of Physics. [S0034-6748(00)02104-3].