Coherent optical characterization of magnetooptical spatial light modulators.
A precision optical system, developed for characterizing the amplitude and phase properties of spatial light modulators, was used to characterize a 48 x 48 pixel magnetooptic spatial light modulator (MOSLM). Considerable variations in the amplitude (+/-25%) and phase transmittance (+/-50%) over the area of a given pixel were observed with coherent light illumination. The pixel-to-pixel variations in the average amplitude (+/-5%) and average phase (+/-6%) were considerably less. The contrast ratio and the polarization rotation for full frame monochromatic illumination were ~10:1 and 11.25 degrees , respectively. For illumination within a single pixel, the contrast ratio and polarization rotation were ~100:1 and 14.0 degrees , respectively. A theoretical model is presented showing that the reduced values for full frame illumination may be described by the coherent addition of light of unrotated polarization (transmitted between pixels and around the edges) with the polarization rotated light. The amplitude and phase characteristics of the MOSLM were found to be a very stable with repeated switching of the pixel and with switching of neighboring pixels. This stability is a central requirement in coherent optical information processing.
Hartman
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Gaylord
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