Abstract: An optically addressed spatial light modulator includes a reflective modulation element, a detector for detecting radiation, a micro-lens focusing a write beam on the detector and a read beam on the modulator element, and a circuit receiving a signal output from the detector generated in response to the write beam. The circuit alters the modulation element in accordance with the signal from the photodetector. The read beam is thus modulated in accordance with the amount of alteration of the modulation element. The read and write beams intercept the micro-lens at different angles and may have the same or differing wavelengths. Including multiple photodetectors on a single pixel allows use of a plurality of write beams. An array of the elements may be used to modulate a plurality of read beams.