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Light Scanner Employing a Nematic Liquid Crystal

IP.com Disclosure Number: IPCOM000078518D
Original Publication Date: 1973-Jan-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 3 page(s) / 33K

Publishing Venue

IBM

Related People

Freiser, MJ: AUTHOR

Abstract

It is known that nematic liquids are characterized by a relatively large birefringence. This characteristic makes it possible, employing electric fields, to orientationally deform the monocrystalline nematic film to thereby attain a relatively large gradient in the index of refraction across the film. Thereby, light of appropriate polarization passing through the film will be deflected. There is described a device whereby a light beam can be controllably deflected in two dimensions over a wide angle, i.e., a light scanner, the device comprising a nematic liquid to enable the utilization of the inherent birefringence of the liquid crystal material.

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Light Scanner Employing a Nematic Liquid Crystal

It is known that nematic liquids are characterized by a relatively large birefringence. This characteristic makes it possible, employing electric fields, to orientationally deform the monocrystalline nematic film to thereby attain a relatively large gradient in the index of refraction across the film. Thereby, light of appropriate polarization passing through the film will be deflected. There is described a device whereby a light beam can be controllably deflected in two dimensions over a wide angle, i.e., a light scanner, the device comprising a nematic liquid to enable the utilization of the inherent birefringence of the liquid crystal material.

In Fig. 1, there is diagrammatically depicted an arrangement wherein the film 10 of nematic fluid, having the crystals therein vertically aligned, is contained between two parallel transparent electrodes 12 and 12'. The surfaces of electrodes 12 and 12' are treated such that there is imparted to film 10, an optically uniaxial character with the optic axis parallel to the plane of electrodes 12 and 12'. The nematic fluid constituting film 10 is chosen to have a positive dielectric anisotropy, i.e., the optic axis will tend to align itself parallel to an imposed electric field.

In considering the operation of the arrangement in Fig. 1, let it be assumed that one of the electrodes, i.e., electrode 12' is maintained at ground potential and that a potential V(0) is applied across the length of electrode 12. In this connection, the resistance of electrode 12 is chosen such that no excessive current or consequent heating of electrode 12 occurs. With the application of the voltage to electrode 12, there will be a voltage gradient thereacross and a field gradient in the nematic fluid. At a point where the voltage across film 10 is sufficiently high, 10 volts for example for a material which has a large dielectric anisotropy, the alignment of the crystals in the nematic fluid will be substantially perpendicular to the electrodes, and the index of refraction for light passing through film 10 will...