title: Two-tone frequency modulation spectroscopy from laser light scattered off a hard target.
abstract: One can apply two-tone frequency modulation spectroscopy techniques to the detection of gas-phase species by using laser light scattered from hard targets. High sensitivities are demonstrated, with a minimum detectable absorption of 10(-4) possible with a simple apparatus. The effects of laser speckle on the FM signal are described, and we show that the detection signal-to-noise ratio can be improved by collecting an increased number of speckle cells.
authors.forename: P E
authors.initials: PE
authors.lastname: Powers
authors.forename: C A
authors.initials: CA
authors.lastname: Taatjes
authors.forename: T J
authors.initials: TJ
authors.lastname: Kulp