Electric lamp and discharge devices – With optical device or special ray transmissive envelope – Polarizer or special ray transmission
Patent
1998-01-09
2000-01-25
Day, Michael
Electric lamp and discharge devices
With optical device or special ray transmissive envelope
Polarizer or special ray transmission
362 19, 362247, 353 20, 349 9, G02B 2710
Patent
active
060182148
ABSTRACT:
The illumination system (21) includes two radiation sources (23, 25) and an optical system for concentrating the radiation into beams, a common polarizing system (11) for splitting the beams (b.sub.I, b.sub.II) into linearly polarized sub-beams, and at least one polarization-rotating element (35). The polarizing system includes at least one optically transparent plate (11) having a refractive index n.sub.0 and a first face and a second face. At least one of these faces is provided with an optically thin layer having a refractive index n.sub.1 which is larger than n.sub.0. The light path of the sub-beams whose directions of polarizations are not to be converted incorporates a reflector (41, 43) for reflecting the sub-beams into the same direction of propagation as that of the other sub-beams. The chief ray of these beams and the normal on the plate (11) enclose an angle which is substantially equal to the Brewster angle which holds for the interface between the optically thin layer and a medium surrounding the polarizing element (11).
REFERENCES:
patent: 4638309 (1987-01-01), Ott
patent: 4716337 (1987-12-01), Huiskes et al.
patent: 5029986 (1991-07-01), De Vaan
patent: 5098184 (1992-03-01), van den Brandt et al.
patent: 5394204 (1995-02-01), Shigeta et al.
patent: 5486884 (1996-01-01), De Vaan
patent: 5765934 (1998-06-01), Okamori et al.
"Polarizing beam splitters for infrared and millimeter waves using single-layer-coated dielectric slab or unbacked films" by R.M.A. Azzam in Applied Optics, vol. 25, No. 23, Dec. 1986.
Day Michael
Faller F. Brice
U.S. Philips Corporation
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