Tunable color filter
AssigneeCambridge Research & Instrumentation, Inc.
InventorPeter Miller
Life of this patent
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Abstract
A color filter having an optical switch element located between a neutral linear polarizer and a second color-selective linear polarizer, followed by one or more optical retarders and a second neutral linear polarizer. When a second optical switch element is incorporated, three color states are produced. The filter may also comprise a guest host type cell as the optical switch element. The resulting color filter exhibits high performance both for on-axis and off-axis rays and can be designed to produce a wide range of colors.
Claims54
A tunable filter system for filtering light, comprising in optical alignment:
- (a) a first neutral linear polarizer;
- (b) an optical switch;
- (c) a color-selective polarizer;
- (d) an optical retarder;
- and
- (e) a second neutral linear polarizer, said elements being arranged in a series order selected from a group of orders consisting of (a) through (e) and (e) through (a).
A tunable filter system for filtering light, comprising in optical alignment:
- (a) a first neutral linear polarizer;
- (b) an optical switch containing a color selective dye for selectively passing a preselected wavelength of light;
- (c) an optical retarder element having a crystal axis oriented at substantially 45 degrees relative to said first neutral linear polarizer;
- and
- (d) a second neutral linear polarizer, said elements being arranged in a series order selected from a group of orders consisting of (a) through (d) and (d) through.
A tunable color filter system for filtering light, comprising in optical alignment:
- (a) a first neutral linear polarizer having a preselected polarization axis;
- (b) an optical switch capable of selectably transmitting light in a first substantially linear polarization state and a second substantially linear polarization state, said second polarization state being substantially orthogonal to said first polarization state;
- (c) a color-selective polarizer having an axis substantially parallel to a polarization state selected from a group consisting of said first polarization state and said second polarization state;
- (d) an optical retarder having a retarder crystal axis substantially at an angle selected from a first group of angles consisting of substantially 45.degree. greater than said first polarization state and substantially 45.degree. less than said first polarization state;
- and
- (e) a second neutral linear polarizer having a polarization axis substantially at an angle selected from a second group of angles consisting of substantially parallel to said first polarization state and substantially parallel to said second polarization state, said elements being arranged in a series order selected from a group of orders consisting of (a) through (e) and (e) through (a).
A tunable filter system for filtering light, comprising in optical alignment:
- (a) a first neutral linear polarizer having a first preselected polarization axis;
- (b) a twisted nematic guest host liquid crystal cell containing a color-selective dye and having a liquid crystal axis substantially parallel to said first preselected polarization axis;
- (c) an optical retarder having a retarder crystal axis substantially 45.degree. to said first preselected polarization axis;
- and
- (d) a second neutral linear polarizer having a second preselected polarization axis, said second preselected polarization axis having an orientation selected from a group consisting of substantially parallel to said first preselected polarization axis and substantially perpendicular to said first preselected polarization axis, said elements being arranged in a series order selected from a group of orders consisting of (a) through (d) and (d) through (a).
Dependencies are inferred from the claim text.