Patent ID: 8503701

Claim:
A directional microphone, comprising: a) a differential microphone diaphragm having an optical diffraction grating which has a rocking motion about a pivot axis with respect to a body in response to acoustic waves, wherein the optical diffraction grating changes angular orientation with respect to the body during rocking; b) a cover disposed in fixed position with respect to the body, having at least one acoustic aperture configured to filter particulate contamination and to transmit sound pressure from an external environment to the differential microphone diaphragm, and an optically reflective surface disposed proximate to the optical diffraction grating; and an optical interferometer comprising an optical emitter having a fixed position with respect to the body and with respect to the optically reflective surface of the cover, in operative relationship to said diaphragm configured to interferometrically detect the rocking motion of the differential microphone diaphragm with respect to the optically reflective surface, in response to the acoustic waves.