Optical: systems and elements – Lens – With multipart element
Patent
1994-03-21
1995-08-29
Ben, Loha
Optical: systems and elements
Lens
With multipart element
359741, G02B 308
Patent
active
054465940
ABSTRACT:
A low-profile transmissive overhead projector employs a folded optical path and an off-axis Fresnel lens condensing system which includes a catadioptric lens element. This lens provides a fast condensing system which allows collimation, dispersion, or concentration of light striking the lens at a high angle of incidence, with efficient transmission to the far edge of the lens. This also enables additional reduction in the OHP base height by allowing the single mirror to be mounted at a flatter angle, with the light source still maintained at a position below (and adjacent) the stage. A novel catadioptric lens design further imparts achromaticity to the element, so that it may be constructed of any material, regardless of its index of refraction. The condensing system may have a single or doublet catadioptric lens.
REFERENCES:
patent: 4118761 (1978-10-01), Dey
patent: 4719547 (1988-01-01), Vanderwerf
patent: 4755921 (1988-07-01), Nelson
patent: 4952053 (1990-08-01), Behr
patent: 4969733 (1990-11-01), Jewison
Nelson John C.
Vanderwerf Dennis F.
Ben Loha
Griswold Gary L.
Kirn Walter N.
Minnesota Mining and Manufacturing Company
Musgrove Jack V.
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