Appeal No. 96-1368
Application 08/080,891
before the liquid crystal material is introduced into the cell
(Murty at 1). After a while, the liquid crystal material
starts crystallizing and when the crystallization is complete,
it acts like a polarizing prism (id.). The resulting cell can
be used to separate two orthogonally polarized component of a
light beam and in this sense is equivalent to a Rochon or
Wollaston prism (id.). Murty does not disclose the use of a
polymerized liquid crystal material.
De Vaan describes a different type of prior art liquid
crystal beam splitter, its associated problems, and the
objects of his invention as follows (col. 1, lines 10 to 51):
According to the state of the art a
polarisation-sensitive beam splitter can be
manufactured in the form of a Wollaston
prism as described in McGraw-Hill
Encyclopedia of Science and Technology,
vol. 10, page 499 (1960). To avoid the use
of birefringent prisms, a polarisation-
separating layer which is interposed
between two transparent elements can be
used in known manner, said elements may be
composed of ordinary glass or of a
synthetic resin having the same single
refractive index, see United States Patent
Specification US 4,702,557. In said
specification, the polarisation-separating
birefringent layer consists of a liquid-
crystalline layer having a thickness of 5
to 10 Fm. One of the refractive indices of
said layer must be equal to the refractive
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