title: Simultaneous measurement of spectra at multiple ranges using a single spectrometer.
abstract: We have designed and built an instrument having the capability to measure and display spectra at multiple ranges near simultaneously in real time. An excitation laser beam is oriented parallel to and offset from the axis of the light collection optics. The image of the laser beam is then displaced with range. Multiple optical fibers collect the displaced images at different ranges. The output ends of these fibers are positioned vertically along the input slit of a spectrometer that disperses the light from each fiber along different rows of the spectrometer's two-dimensional detector array. The detector array rows then give an immediate visual comparison of spectra at different ranges. A small prototype of this system covering a range from 3 to 13 m has been built. It has been successfully tested using containers holding two distinct fluorescent dyes. Numerical simulations indicate that the technique can be extended to longer-range systems.
authors.affiliation: Hawaii Institute of Geophysics and Planetology, University of Hawaii, 2525 Correa Road, Honolulu, Hawaii 96822, USA. lienert@soest.hawaii.edu
authors.forename: Barry
authors.initials: B
authors.lastname: Lienert
authors.forename: John
authors.initials: J
authors.lastname: Porter
authors.forename: Shiv K
authors.initials: SK
authors.lastname: Sharma