Patent ID: 7764415

Claim:
A high retardation-amplitude photoelastic modulator comprising in combination: a photoelastic element having a first end, an opposing second end, an optical axis passing through the first end and the second end, and a surface disposed between the first end and the second end; at least one active cell comprising: two spaced-apart first mechanical drivers affixed to the surface and having a first chosen distance therebetween along the optical axis; and a second mechanical driver affixed to the surface of said photoelastic element at a second chosen distance from one of said two first mechanical drivers along the optical axis and between said two first mechanical drivers; first means for driving one of said two first mechanical drivers; second means for driving a second of said two first mechanical drivers; third means for driving said second mechanical driver, wherein a standing elastic wave having a node along the optical axis at positions corresponding to each of said two first mechanical drivers, and an antinode along the optical axis between the nodes, and confined to said at least one active cell is generated, and wherein induced birefringence is produced along the optical axis in said at least one active cell between said two first mechanical drivers; and means for directing linearly polarized optical radiation along the optical axis, the optical radiation having an initial phase and a direction of polarization parallel to a principal axis, whereby the initial phase of the optical radiation is monotonically retarded as the optical radiation propagates along the optical axis within said at least one active cell.