Patent ID: 6339486
Filing Date: 2002-01-15
Classification: G02B,G02F

Abstract:
An apparatus comprising:a fit pair of holographic optical elements electrically switchable between active and inactive states; wherein a first holographic optical element of the first pair, when operating in the inactive state, is configured to transmit first bandwidth light substantially unaltered; wherein a second holographic optical element of the first pair, when operating in the inactive state, is configured to transmit first bandwidth light substantially unaltered; wherein the first holographic optical element, when operating in the active slate, is configured to diffract first bandwidth light; wherein the second holographic optical element, when operating in the active state, is configured to diffract first bandwidth light received on a first surface thereof, wherein first bandwidth light received on the first surface thereof and subsequently diffracted by the second holographic optical clement, emerges from the first surface thereof, and; a quarter wave plate positioned between the first and second holographic optical elements of the first pair.