Abstract
A descriptive survey is presented of the acousto-optical coherence modulation that aims to produce a coherence-controllable illumination source. The optical mutual coherence function derived analytically has spatial and temporal periodicities, determined by the wavelength and the frequency of the ultrasonic wave. The optical mutual intensity results from the mutual coherence function obtained, and its modulation characteristics are described in detail. Spatial coherence modulation can be controlled by the ultrasonic power level. Extension to two-dimensional modulation is also presented. The periodicity deteriorates when a random frequency modulation is imposed on the ultrasonic wave. More general aspects in the Fresnel diffraction zone behind the output plane of an ultrasonic column are discussed. The optical mutual intensity is always the same in the longitudinal direction but still has lateral periodicity.
© 1986 Optical Society of America
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