Infrared polarizer
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsYoshito Miyatake, Shinya Sannohe
Life of this patent
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Abstract
A polarizer comprising; a substrate transparent to a light of actual use and optical thin films of a higher refractive index than that of said substrate deposited on both surfaces of said substrate. The substrate is arranged so as to receive the incident light obliquely thereto. When the incident angle and the thickness of the optical thin film are optimally selected, the transmittance for the P polarized light can be made approximately 100%, while that for the S polarized light very small. The polarizer can extract a substantially linearly polarized light from natural light, A projection image display system has the polarizer as its pre-polarizer. The polarizer is also useful for infrared radiation.
Claims18
A polarizer comprising:
- at least one polarization-selective mirror including a substrate made of a substance which is substantially transparent to infrared radiation, and optical thin films with a higher refractive index than that of said substrate disposed on opposite surfaces of said substrate, said at least one mirror being obliquely arranged with respect to a given optical axis such that a transmittance of the polarizer for P polarized light incident upon the polarizer along said optical axis is at a maximum value.
A polarizer comprising:
- at least one polarization-selective mirror including a substrate made of a substance which is substantially transparent to infrared radiation, and optical thin films with a higher refractive index than that of said substrate disposed on opposite surfaces of said substrate, said at least one mirror being obliquely arranged with respect to a given optical axis such that a transmittance of the polarizer for P polarized light incident upon the polarizer along said optical axis is at a maximum value,
- said polarizer satisfying the following conditions:
- ##EQU7## where n.sub.0 represents a refractive index of an exterior medium;
- n.sub.1 represents a refractive index of the optical thin films;
- n.sub.2 represents a refractive index of the substrate;
- d represents a thickness of the optical thin films;
- .theta..sub.0 represents an incident angle at which the light enters from the exterior medium into the optical thin film, .theta..sub.1 represents an angle of refraction of infrared radiation in said optical thin film;
- .theta..sub.2 represents an angle of refraction of infrared radiation in said substrate;
- and .lambda. represents a main wavelength of infrared radiation traveling through air.
Dependencies are inferred from the claim text.