ASTIGMATIC PHASE CORRECTION FOR THE MAGNETOOPTIC SPATIAL LIGHT-MODULATOR

We report a simple low-cost technique for evaluating the phase distort ion in a magneto-optic spatial light modulator. We find that the domin ant distortion is caused by astigmatism and is easily compensated by e ncoding of the complex-conjugate pattern onto the device. Two experime ntal results are shown. First, the focused spot size from a Fresnel le ns is sharpened when the aberrations are corrected. Second, we show th at the pattern that generates a first-order Bessel-function nondiffrac ting beam does not work unless the aberrations are corrected.