Modulation transfer function characterization and modeling of a Scophony infrared scene projector

Eric F. Schildwachter; Glenn D. Boreman

doi:10.1117/12.56005

1 November 1991 Modulation transfer function characterization and modeling of a Scophony infrared scene projector

Eric F. Schildwachter, Glenn D. Boreman

Author Affiliations +

Optical Engineering, Vol. 30, Issue 11, (November 1991). https://doi.org/10.1117/12.56005

Abstract

A Scophony-configuration infrared scene projector, consisting of a raster-scanned CO₂ laser and an acousto-optic (AO) modulator, was characterized for modulation transfer function (MTF) performance. The MTF components considered in the model were the Gaussian beam input to the AO cell, the finite aperture of the scan mirror, the width of the detector in the image plane, the transfer function of the amplifier electronics, and a term caused by Bragg-angle detuning over the bandwidth of the amplitude modulation (AM) video signal driving the AO cell. The finite bandwidth of the input video signal caused a spread in the Bragg angle required for maximum diffraction efficiency. In the Scophony configuration, a collimated laser beam enters the AO cell at only one particular angle, so a falloff of diffraction efficiency (and hence MTF) resulted as the modulation frequency was increased. The Bragg-angle detuning term was found to dominate the measured system MTF.

Citation Download Citation

Eric F. Schildwachter and Glenn D. Boreman "Modulation transfer function characterization and modeling of a Scophony infrared scene projector," Optical Engineering 30(11), (1 November 1991). https://doi.org/10.1117/12.56005

Published: 1 November 1991

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