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Browse Prior Art Database

Steep Angle Polarizer Light Pipe

IP.com Disclosure Number: IPCOM000119130D
Original Publication Date: 1997-Dec-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Tanase, H: AUTHOR

Abstract

Disclosed is a backlight, with a series of steeply inclined reflective surfaces, that emits linearly polarized light from its surface of illumination. The angle of inclination of the reflective surfaces relative to the direction of the normal incidence is from 55 through 70 degrees. With uncollimated input, this backlight produces highly polarized output in oblique directions, which subsequently is corrected by the use of a prismatic film or by other devices of equivalent function.

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Steep Angle Polarizer Light Pipe

      Disclosed is a backlight, with a series of steeply inclined
reflective surfaces, that emits linearly polarized light from its
surface of illumination.  The angle of inclination of the reflective
surfaces relative to the direction of the normal incidence is from 55
through 70 degrees.  With uncollimated input, this backlight produces
highly polarized output in oblique directions, which subsequently is
corrected by the use of a prismatic film or by other devices of
equivalent function.

      One means of producing polarized output is to fabricate a
series of optical boundaries that are at the Brewster's angle to the
normal incidence and give collimated input that approximates normal
incidence.  The angle of inclination of the planes designed this way
is approximately 45 degrees when the refractive indices of the bulk
material and the adhesive are selected close.  When the input is
uncollimated, however, the 45 degree design that is optimized for
collimated input allows light to leak in off-normal directions and
the total polarization ratio is greatly diminished.

      This degradation of output due to massive off-angle leakage can
be averted by altering the angle of inclination to the range of 55
through 70 degrees.  This steep angle design suppresses leakage and
maintains high polarization ratio in output.  The internal reflective
planes can be fabricated by various methods, which include bonding a
pair of identical...