Patent ID: 7349048

Claim:
A shutter, comprising: a variable retarder wherein the variable retarder includes a retarder transmission axis; a polarizer wherein the polarizer is placed in a series with an output light path of the variable retarder and wherein the polarizer includes a polarizer transmission axis parallel to an axis of polarization of an input S polarized light input to an input of the variable retarder and wherein the retarder transmission axis is set at selected angle to the polarizer transmission axis; and an electronic video image analyzer circuit coupled to the variable retarder and polarizer and including circuitry to adjust the retarder to a variable amount of retardation between a fully unenergized state and a fully energized state wherein the variable retardation varies between 0 lambda retardation and ½ lambda retardation in correlation to a contrast ratio of a current video image.