Abstract

As a coherent optical information processor, a microchannel spatial light modulator (MSLM) can perform linear and nonlinear operations, as well as basic image and logic operations.1 The MSLM has a binary or hardclip thresholding mode, where input write image intensities below a threshold produce one output intensity level, and intensities above the threshold produce a second output level. The three key parameters, threshold level, and also lower and upper output levels are fully adjustable by proper setting of the MSLM drive voltages. 2 The gamma value is also adjustable with very high gammas of 3.8-6.5 having been demonstrated. Logarithmic transformation of image input intensities has been demonstrated by multiplying the input image by a suitable halftone screen, followed by high gamma hardclipping by the MSLM. One converts the continuous input image into a pulse width modulated binary output. The binary output is processed with a low pass filter to recover the logarithmic intensity image in a coherent optical system.

© 1989 Optical Society of America