MULTISPOT ACOUSTOOPTIC MODULATOR

PURPOSE:To reduce sound inputs and to prevent a change of diffracting direction caused by the generation of heat, by using repetitive interferences to increase the mutual functioning length between the sound and light waves and at the same time applying a thin-film producing technique to sufficiently decreasing the thickness of a sound solid material. CONSTITUTION:An output beam given from an He-Cd laser 1 is made incident to a diffraction cell 3 with an inclination. In this case, the direction of electric deviation is within an incident surface. The cell 3 has the dielectric multilayer reflecting films 3b1 and 3b2 formed on the surfaces parallel to each other on a tellurium glass plate 3a. The equidistant three frequencies fa1-fa3 are produced by oscillators 4a1-4a3 and controlled at the gates 4b1-4b3 and according to the digital image signal to be synthesized into a signal. This synthetic signal is amplified by a high frequency amplifier 4c and applied to a piezoelectric transducer 4d. The components which received the Bragg diffraction at each of the sound fields corresponding to the three frequencies are condensed at a lens 5a and form a light spot pattern at 5d.