Patent ID: 7133184

Claim:
A variable grating diffractive light modulator, comprising: a light transmissive plate to transmit light; a plurality of first reflecting plates attached to a lower surface of the light transmissive plate to be arranged in a row, each of the first reflecting plates having a first reflective surface on a light transmissive plate contact surface thereof; a plurality of second reflecting plates provided under the first reflecting plates to be spaced apart from the first reflecting plates at a predetermined interval while being arranged in a row, each of the second reflecting plates having a second reflective surface to reflect incident light falling downwardly; and a plurality of actuating units acting on the second reflecting plates, and moving between a first position wherein the first reflective surfaces and the second reflective surfaces form a plane mirror, and a second position wherein the first and second reflective surfaces diffract the incident light, the actuating units comprising piezoelectric material, the piezoelectric material disposed on electrodes, so that the actuating unit shrinks or expands when voltage is applied to the electrodes.