Computerized rapid-scan spectroscopy at NAVWPNSUPPCEN Crane

This report contains a description of a computerized spectroscopic data acquisition and analysis system used to analyze flare emission and smoke absorption. The system enables the computer generation of system corrected and signal averaged plots of spectral radiant intensity versus wavelength in the case of flare emissions, and the generation of plots of transmittance versus wavelength as a function of time in the case of smoke obscuration experiments. The system consists of several commercially available components. A dual channel scanning spectrometer, presently set up for the 1.7 to 4.7 micrometer region, enables spectra to be obtained repetitively with scan times of 1, 50, 100, or 500 msec, and with a resolution (at the slowest scan times) of 0.004 micrometers. Two channels of spectroscopic data, a number of channels of radiometric data, and various synchronization pulses are recorded on a 14-channel analog tape recorder. The spectroscopic and radiometric data are then digitized, using as many as 2,000 points per spectral scan per channel. System corrected, absolute intensity spectra are generated in the computer by calculations involving the flare spectral data, spectra of a Globular source, and the radiometric data. The system is flexible in that a variety of gratings, filters, and detectors make it possible to use this system in the near ultraviolet, visible, near, and middle infrared.