Abstract: A polarizer including liquid crystal material and a surface or surfaces for cooperating with the liquid crystal material to control polarization of light which is incident in a direction normal to the polarizer by at least one of refraction and total internal reflection of one polarization component of the light while transmitting the other polarization component substantially in the direction without refraction or total internal reflection, the surface or surfaces including plural grooves in cooperative relationship with the liquid crystal material.

Abstract: An apparatus for responding to incident electromagnetic radiation includes a first medium having a surface and through which incident electromagnetic radiation may be transmitted, a second such medium having a surface, the surfaces being generally parallel, and smectic liquid crystal between said surfaces and aligned generally in parallel in layers that extend generally parallel to each other and perpendicularly to such surfaces (bookshelf alignment), the liquid crystal material being operative to undergo self-focusing in response to a characteristic of incident electromagnetic radiation exceeding a value and being cooperative with at least one of such media thereby automatically to limit the energy or energy density of electromagnetic radiation exiting the apparatus.

Abstract: Substituted-hydrocarbylthio phenyl-pyrimidines are disclosed which exhibit smectic A phases over a wide temperature range and are useful in formulating smectic A compositions. The liquid-crystal compositions formulated utilizing the smectic A compounds of the present invention have particular application in smectic cells such as laser smectic liquid-crystal light valves and optical limiters used in high performance environments.

Abstract: A light control device includes a light shutter having a pair of polarizers and a liquid crystal device operative in response to a prescribed input to control transmission of light therethrough, and a variable polarizer optically aligned with respect to said light shutter and operative to control light transmitted therethrough in response to a prescribed input; the light shutter is operative relatively fast in response to application of electric field to reduce light transmission and the variable polarizer is operative in the event of a power loss, which would cause the light shutter to stop light blocking, to provide a safety light blocking function. The light control device may be employed in a welding helmet or other device intended to provide protection to the eyes of an individual or other animate or inanimate object from selected electromagnetic energy, such as that produced by welding or other source.