Real-time Optical Intensity Correlator Using Photorefractive BSO and a Liquid Crystal Television

The use of photorefractive Bi12SiO20 (BSO) as a dynamic holographic medium in optical processing systems has been the subject of much activity. Typical operations carried out include edge enhancement [1], novelty filtering [2] and the correlation of optical signals [3]. However the use of BSO in coherent correlator systems is hindered by positional problems [3,4] as the crystal must be inserted at the Fourier plane of the transforming lens(es) to a high degree of accuracy (to within 0.5 % of the focal length of the lens as determined in ref 3).