Phenomenology of exploding ordnance using spectrally and temporally resolved infrared emissions

Infrared emissions from the detonation of three bomb types and four weights in a series of 56 events were recorded by a Fourier transform interferometer in the mid-IR (1800-6000 cm(-1)) at temporal and spectral resolutions of 0.047 s and 16 cm(-1), respectively. Spectrally-resolved time profiles from two representative detonation events were selected for this study. Two parameterized, empirical functions adequately represent the temporal signatures taken from four spectral bands in which atmospheric attenuation losses are small. Each function is the sum of either two or three exponential terms modulated by delayed switching functions. The number of exponential terms required to fit each temporal profile depends on the explosive and varies with the frequency. The dimensionality of the spectrally-resolved temporal signatures is significantly reduced by establishing these characteristic timescales. Such feature extraction is critical for proposed event classification schemes.