Determination of Spectrally Resolved Transmittance and Extinction Coefficients for Obscurants at Smoke Week XIV
Abstract
Since the completion of Smoke Week XIII in May 1991, significant enhancements have been incorporated into the U.S. Army Research Laboratory, Battlefield Environment Directorate's Mobile Atmospheric Spectrometer (MAS). The key components of the MAS are a Fourier transform spectrometer and a 31-in Coude telescope. The useful spectral coverage of the instrument is about 800 to 5000/cm (2 to 12.5/micrometers. Although the instrument is capable of spectral resolution as high as 0.04/cm, a resolution of 4/cm was used during Smoke Week XIV. In preparation for Smoke Week XIV, a high-speed parallel spectrometer-to- computer interface was installed. Although this interface arrived too late to optimize fully, the increase in spectrometer performance was impressive. Rather than slewing on and off source, a mechanically chopped source was used to increase data acquisition rate and maintain a constant line of sight. With these two enhancements, the number of spectra collected increased by a factor of six. With more than 9.000 smoke spectra collected, a new data analysis approach was required. This requirement evolved into a three-dimensional spectral movie that displays transmittance (or radiance) versus spatial frequency as a function of time. In this manner, trials incorporating hundreds of spectra may be viewed. The MAS line of sight was in close proximity and parallel to the nephelometer grid. As a result, obscurant concentration length (CL) as determined from nephelometer data and transmittance as determined from MAS data have been manipulated to derive spectrally resolved mass extinction coefficients for selected obscurants
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1994
- Accession Number
- ADA286473
Entities
People
- Frank T. Kantrowitz
- Troy D. Gammill
- William M. Gutman
Organizations
- United States Army Research Laboratory