Interim rept. 1 Aug-31 Oct 1975
HUGHES RESEARCH LABS MALIBU CA
Pagination or Media Count:
Target speckle modulation effects have been investigated experimentally using a number of scaled realistic targets with different shapes and surface textures, and analytically using theoretical target signature models in a computer simulation model of a multidither COAT system. The experimental results have shown that maximum contrast ratios of 0.79 can occasionally be obtained, but that the average is much lower. Significant receiver aperture integration effects cause reduction of the contrast ratio. Temporal frequency spectra obtained by rotation of the targets agree with spatial frequency data obtained by fast Fourier transform processing of the target signature data. Preliminary computer simulation results using high contrast ratio speckle data from GRC show degraded COAT system performance. A preliminary adjustment of the COAT simulation model has led to reduced susceptibility to high contrast speckle modulation. In addition, theoretical arguments, corroborated by the experimental results, indicate that such high contrast ratios are not realistic at visible wavelengths.
- Optical Detection and Detectors