Polarizing beam splitter
First Claim
1. A polarizing beamsplitter, comprising:
- first and second prisms; and
a multiple layer, polarization-sensitive film disposed between the first and second prisms, the polarization-sensitive film being formed from alternating first and second polymer layers, the polarization-sensitive film having a structural orientation defining x- and y-polarization axes parallel to the film and a z-axis perpendicular to the film, the first polymer layer being birefringent and having a refractive index nz substantially equal to one of nx and ny, where nx, ny and nz are the refractive indices for light having electric field components parallel to the x-axis, y-axis and z-axis respectively;
wherein light propagating through the polarizing beamsplitter is refracted away from a normal to the polarization-sensitive film on passing from one of the first and second prisms to the polarization-sensitive film.
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Abstract
An optical imaging system including a wide-angle Cartesian polarizing beam splitter, light valve illumination optics having an f/#≦2.5, and at least one reflective light valve. The Cartesian polarizing beam splitter (PBS) has a structural orientation defining fixed polarization axes. The use of a Cartesian PBS allows the development of systems using curved PBS that provide higher light output and/or replace or augment other optical components. By recognizing and advantageously applying properties of wide-angle Cartesian polarizers, the present invention discloses a high-efficiency optical imaging system capable of functioning at f/#'"'"'s equal to or below f/2.5 while maintaining a contrast ratio of at least 100 to 1, or, more preferably, 150 to 1 in a projection system configuration.
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Citations
26 Claims
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1. A polarizing beamsplitter, comprising:
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first and second prisms; and
a multiple layer, polarization-sensitive film disposed between the first and second prisms, the polarization-sensitive film being formed from alternating first and second polymer layers, the polarization-sensitive film having a structural orientation defining x- and y-polarization axes parallel to the film and a z-axis perpendicular to the film, the first polymer layer being birefringent and having a refractive index nz substantially equal to one of nx and ny, where nx, ny and nz are the refractive indices for light having electric field components parallel to the x-axis, y-axis and z-axis respectively;
wherein light propagating through the polarizing beamsplitter is refracted away from a normal to the polarization-sensitive film on passing from one of the first and second prisms to the polarization-sensitive film. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A polarizing beamsplitter, comprising:
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first and second prisms; and
a multiple layer, polarization-sensitive film disposed between the first and second prisms, the polarization-sensitive film being formed from alternating first and second polymer layers, the polarization-sensitive film having a structural orientation defining x- and y-polarization axes parallel to the film and a z-axis perpendicular to the film, the first polymer layer being birefringent and having a refractive index nz substantially equal to nx, where nx, ny and nz are the refractive indices for light having electric field components parallel to the x-axis, y-axis and z-axis respectively, the x-axis defining a transmission polarization state through the polarization-sensitive film, the refractive index for x-polarized light being lower in the polarization-sensitive film than in the first and second prisms. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification