High contrast electro-optic liquid crystal camera iris providing angle independent transmission for uniform gray shades

摘要

A high-contrast electro-optic liquid crystal camera iris (10) provides angle independent transmission for uniform gray shades. The liquid crystal iris comprises a combination of first and second liquid crystal devices (12, 14) arranged in optical series and positioned between optical polarizers (46, 48). The director field (18) of the second liquid crystal device is a mirror image of the director field (16) of the first liquid crystal device, and the first and second liquid crystal devices are placed together so that the azimuthal directions (42) of the surface-contacting directors (18c, 22c) are in parallel alignment at the adjoining or confronting surfaces of the substrates (242, 321) of the first and second liquid crystal devices. The liquid crystal iris provides, therefore, less angular variation of intermediate transmittances compared with that provided by prior art liquid crystal irises.