Illumination system and method with efficient polarization recovery
First Claim
1. An illumination system comprising:
- a light source having a light reflector;
a collimator for collimating light provided from the light source;
a quarter-wave retardation plate for transmitting light collimated by the collimator, the so-transmitted light comprising a pair of orthogonal linearly polarized components of respective first and second linear polarization types; and
a light-reflective linear polarizer for transmitting light of the component of the first linear polarization type and reflecting light of the component of the second linear polarization type, such reflected light being transmitted back through the retardation plate and being converted by it into circularly polarized light which is of a first handedness and which is directed by the collimator to the light reflector to be reflected and thereby converted into circularly polarized light of a second handedness opposite to the first handedness, such circularly polarized light of the second handedness being collimated by the collimator, being subsequently transmitted through the retardation plate, and being converted by it into linearly polarized light which is of the first linear polarization type and which is transmitted through the polarizer.
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Accused Products
Abstract
Light provided by a light-reflective light source (102) in an illumination system having polarization recovery is collimated by a collimator (104) and transmitted through a quarter-wave retardation plate (106) to produce light having orthogonal linearly polarized components of first and second linear polarization types. A light-reflective linear polarizer (108) largely transmits the first-linear-polarization-type component and reflects the second-linear-polarization-type component which is then largely converted by the retardation plate into circularly polarized light of a first handedness and directed by the collimator to the light source to be reflected forward and converted into circularly polarized light of an opposite second handedness. The circularly polarized light of the second handedness is largely collimated by the collimator, converted by the retardation plate into linearly polarized light of the first polarization type, and transmitted through the polarizer to complete the polarization recovery. A light integrator (160 or 170) causes partial fluxes of composite light collimated by the collimator and transmitted through the retardation plate and polarizer to be mixed so as to make the light illumination more uniform.
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Citations
22 Claims
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1. An illumination system comprising:
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a light source having a light reflector; a collimator for collimating light provided from the light source; a quarter-wave retardation plate for transmitting light collimated by the collimator, the so-transmitted light comprising a pair of orthogonal linearly polarized components of respective first and second linear polarization types; and a light-reflective linear polarizer for transmitting light of the component of the first linear polarization type and reflecting light of the component of the second linear polarization type, such reflected light being transmitted back through the retardation plate and being converted by it into circularly polarized light which is of a first handedness and which is directed by the collimator to the light reflector to be reflected and thereby converted into circularly polarized light of a second handedness opposite to the first handedness, such circularly polarized light of the second handedness being collimated by the collimator, being subsequently transmitted through the retardation plate, and being converted by it into linearly polarized light which is of the first linear polarization type and which is transmitted through the polarizer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An illumination method comprising:
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collimating light; causing such collimated light to be transmitted through a quarter-wave retardation plate wherein the so-transmitted light comprises a pair of orthogonal linearly polarized components of respective first and second linear polarization types; transmitting light of the component of the first linear polarization type through a light-reflective polarizer; reflecting light of the component of the second linear polarization type off the polarizer; causing such reflected light to be transmitted back through the retardation plate and converted by it into circularly polarized light of a first handedness; reflecting such circularly polarized light of the first handedness to convert it into circularly polarized light of a second handedness opposite to the first handedness; collimating such circularly polarized light of the second handedness; causing such collimated circularly polarized light of the second handedness to be transmitted through the retardation plate and converted by it into linearly polarized light of the first linear polarization type; and transmitting such linearly polarized light of the first linear polarization type through the polarizer. - View Dependent Claims (20, 21, 22)
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Specification