Patent ID: 6678078
Filing Date: 2004-01-13
Classification: G02B

Abstract:
An apparatus comprising:a first holographic optical element having front and back oppositely facing surfaces, wherein the first holographic optical element is switchable between active and inactive states, wherein the first optical element diffracts first bandwidth light incident on the front surface thereof when operating in the active state, wherein first bandwidth light diffracted by the first holographic optical element emerges from the back surface thereof, and wherein the first holographic optical element transmits first bandwidth light incident on the front surface thereof without substantial alteration when operating in the inactive state; a second holographic optical element having front and back oppositely facing surfaces, wherein the second holographic optical element is switchable between active and inactive states, wherein the second holographic optical element diffracts first bandwidth light incident on the front surface thereof when operating in the active state, wherein first bandwidth light diffracted by the second holographic optical element emerges from the back surface thereof, and wherein the second holographic optical element transmits first bandwidth light without substantial alteration when operating in the inactive state; a display device coupled to an image signal processor, wherein the display device is configured to display a monochrome image frame in response to receiving a frame of image signals generated by the image signal processor; wherein the display device is configured to be illuminated directly or indirectly with diffracted first bandwidth emitted from the first and second holographic optical elements; wherein the first and second holographic optical elements are positioned adjacent each other; wherein the front surfaces of the first and second holographic optical elements are aligned orthogonal to a common axis so that the back surface of the first holographic optical element faces the front surface of the second holographic optical element.