Fast optical thresholding with an array of optical thyristor differential pairs

In this paper an optoelectronic system for fast grey-level image decomposition into binary slices is presented. To perform thresholding we take advantage of the differential nature of optical thyristors and compare the light level of the image pixels with that of a reference intensity. For the input a grey-level image was generated using a liquid crystal spatial light modulator (SLM) and, for the reference intensity, a vertical-cavity surface-emitting laser light source combined with a diffractive fan-out element was used. A decomposition frame rate of 1.0 kHz has been obtained for images with five grey levels.