Simulating systematic scene-change artifacts in Fourier-transform spectroscopy

Kevin C. Gross; Anthony M. Young; Christoph Borel; Bryan J. Steward; Glen P. Perram

doi:10.1117/12.849128

13 May 2010 Simulating systematic scene-change artifacts in Fourier-transform spectroscopy

Kevin C. Gross, Anthony M. Young, Christoph Borel, Bryan J. Steward, Glen P. Perram

Proceedings Volume 7695, Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral Imagery XVI; 76951Y (2010) https://doi.org/10.1117/12.849128
Event: SPIE Defense, Security, and Sensing, 2010, Orlando, Florida, United States

Abstract

Improved understanding of midwave infrared (1-5μm) spectral emissions from detonation fireballs is needed to develop a battle space optical forensics capability. While Fourier-transform spectrometers (FTS) are an attractive tool, interferometer-based spectroscopic measurements can be corrupted when the observed scene intensity systematically varies during the measurement time. Approximating a detonation fireball as a blackbody radiator with a time-varying temperature T and modified by atmospheric attenuation τ(^~ν), double-sided interferograms from an ideal FTS were calculated and converted to measured spectra L_m(^~ν) to characterize the nature and magnitude of scene-change artifacts. T(x) decreased exponentially with optical path difference x, -x_m ≤ x ≤ x_m, at various rates relative to the Michelson mirror speed so that changing scene spectra could be simulated on 1700 ≤ ^~ν ≤ 7900cm^-1 at δ ^~ν = 3.64cm^-1 resolution (x_m = 0.25cm, Hamming apodization). The real part of L_m(^~ν), Re{_Lm(^~ν)}, is well approximated by the instantaneous spectrum at zero path difference, L(^~ν,x = 0). In regions where τ(^~ν) is highly structured, both the imaginary component Im{L_m(^~ν)} and the differences between Re{L_m(^~ν)} and L(^~ν,0) exhibit spectral features, and in general |Im{L_m(^~ν)}|>>|Re{L_m(^~ν)}-L(^~ν,0)|. In a region of highly structured absorption, 2800 ≤^~ν ≤ 3500cm^-1, a 600K decrease in temperature produced RMS values of 62 and 5μW/(cm² • sr •cm^-1) in Im{L_m(^~ν)} and Re{L_m( ^~ν)-L(^~ν,0)}, respectively, compared with an RMS value of 1924μW/ (cm² • sr • cm^-1) in Re{L_m(^~ν)}. A method based on theoretical expressions developed by Kick et al. is devised to interpret L_m(^~ν) and provide estimates of the temporal evolution T(x) when its functional formis not known a priori.

Citation Download Citation

Kevin C. Gross, Anthony M. Young, Christoph Borel, Bryan J. Steward, and Glen P. Perram "Simulating systematic scene-change artifacts in Fourier-transform spectroscopy", Proc. SPIE 7695, Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral Imagery XVI, 76951Y (13 May 2010); https://doi.org/10.1117/12.849128

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