Vapor Detection Sensitivity as a Function of Optical Resolution for a Single Lorentzian Band
Abstract
The objective of this effort is twofold: to begin the development of a computer model for passive infrared (IR) remote sensing vapor detection systems and to provide guidance for the determination of optimum spectral resolution for the remote detection of organic vapors. The target bands are modeled as Lorentzian bands; this allows a fairly simple analytical approach. Several sensor models are compared including: a detector limited sensor model according to Wolfe, and 2 background limited incident photon (BLIP) models based on work by Wolfe and Kingston. The measures of sensitivity are signal to noise ratio (SNR), noise equivalent concentration pathlength (NECL) and noise equivalent delta(T) (NEDT) all as a function of optical bandwidth. Signal to noise ratio, NECL and NEDT values are computed for a typical broad and narrow band associated with organophosphorus compounds. Additionally, the simulant, sulfur hexafluoride (SF6) is evaluated. The results show that gains in sensitivity may be possible in existing remote sensors if the current optical resolution 4/cm, is reduced to 8/cm or 16/cm, although this must be done carefully to ensure no loss in discrimination. It is clear that present systems are limited by detector technology. With true background limited performance and careful optimization to a particular problem, sensitivity improvements of 50 may be possible. D*, Infrared, Signal to noise, FTS, Detection, Fourier transform, XM21, Sensitivity, Optical resolution.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1994
- Accession Number
- ADA283444
Entities
People
- Dennis F. Flanigan
Organizations
- Edgewood Chemical Biological Center