title: Frequency modulation spectroscopy at 1.3microm using InGaAsP lasers: a prototype field instrument for atmospheric chemistry research.
abstract: Two-tone frequency modulation spectroscopy has been used in conjunction with InGaAsP lasers in the 1.3-microm region to monitor weak water vapor absorptions in a long path White cell. Detection electronics that reduce the effect of Johnson noise are described. The system was capable of detecting optical densities corresponding to <1.7 x 10(-6) in a 1-Hz bandwidth. Factors limiting the difference between observed and shot noise limited performance for these types of laser and condition are discussed.
authors.forename: T J
authors.initials: TJ
authors.lastname: Johnson
authors.forename: F G
authors.initials: FG
authors.lastname: Wienhold
authors.forename: J P
authors.initials: JP
authors.lastname: Burrows
authors.forename: G W
authors.initials: GW
authors.lastname: Harris