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.

主权项

1. A high-contrast electro-optic liquid crystal camera iris providing angle independent transmission of incident light for uniform gray shades, comprising:
first and second light polarizing filters; a first liquid crystal device including a spaced-apart pair of first electrode structures and a second liquid crystal device including a spaced-apart pair of second electrode structures, the first and second liquid crystal devices including liquid crystal material mixed with a dye to improve achromatic performance over a range of f-stop settings of the iris, and the first and second liquid crystal devices positioned between the first and second light polarizing filters and arranged in optical series so that a surface of one of the first electrode structures adjoins or confronts a surface of one of the second electrode structures to form an interface between the first and second liquid crystal devices, the interface characterized by substantially no selective polarization state blocking of incident light propagating from one to the other of the adjoining or confronting surfaces of the first and second electrode structures; the first liquid crystal device having spaced-apart first alignment surfaces which are formed on interior surfaces of the first electrode structures and between which are confined first liquid crystal directors, the first liquid crystal directors forming a first director field and including first surface-contacting directors that contact, and define an azimuthal direction on, each of the first alignment surfaces; the second liquid crystal device having spaced-apart second alignment surfaces which are formed on interior surfaces of the second electrode structures and between which are confined second liquid crystal directors, the second liquid crystal directors forming a second director field and including second surface-contacting directors that contact, and define an azimuthal direction on, each of the second alignment surfaces; one of the first and second director fields being a mirror image of the other of the first and second director fields; and the azimuthal directions defined on the first and second alignment surfaces formed on respective ones of the adjoined or confronting first and second electrode structures being in parallel alignment.