| 摘要 |
<p>The two liquid crystal variable optical retarders (24,26) each has an optic axis and a light communicating surface on which the axis is projected, and are positioned between two light polarisers (12,14) so that the projections (36,42) of the optic axes on the light communicating surfaces are orthogonally related. A control circuit (30) is included to selectively provide, for one retarder (24), two amounts of optical retardation of light propagating within the gate to develop respective transmissive and opaque optical states. A second control circuit (32) is included to continuously provide, for the other retarder, a compensating retardation amount that provides independent of wavelength dispersion, an increased extinction ratio for one of the optical states.</p> |
