METHOD AND APPARATUS FOR OBTAINING MODULATED LIGHT INDICATIVE OF AN IMAGE OPERATIONALLY FORMED BY PROJECTING AN INPUTTED IMAGE ON THE FLAT PLATE OF AN OPTICAL INDUCTION REFLECTIVE INDEX CRYSTAL

An optical logic operation apparatus includes an optical induction refractive index crystal having first and second planes parallel to each other and a device for inputting a coherent probe light from the first plane of the crystal. At least one of the first light output from the first plane of the crystal and the second light output from the second plane of the crystal is taken out so that one of the first and second lights is amplified by the two-wave coupling of the probe light reflected by the second plane and the probe light inputted from the first plane and the other light is attenuated likewise by the two-wave coupling. The inputted image is projected onto the crystal by use of light incoherent to the probe light. With the incidence of the incoherent light, a gain distribution corresponding to the inputted image is generated in the crystal so as to modulate the first and second lights spatially.