Self adaptive high pass filtering using photochromic glass

We describe an auto programmable spatial-filtering system using photochromic glass plate as a programmable spatial light modulator, SLM, illuminated by a single wavelength of light. The proposed setup is a conventional 4f coherent optical system. At Fourier plane the filter function is written on the SLM as negative copy of the power spectrum of the input image. The method does not involve numerical processing, and thus, it could be potentially useful for processing large images. Validation experiments are presented.