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US Patent 5151820 - Zoom lens
US Patent Issued on September 29, 1992
Estimated Patent Expiration Date:
May 2, 2011Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
Estimated Patent Expiration Date:
May 2, 2011Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.AbstractA zoom lens, for use in a telescope at infra-red wavelengths or single wavelength visible light, provides a magnification which may be adjusted to either of two predetermined values. The lens comprises a pair (14) of similar elements (15, 16) fixed relative to one another and each having an aspheric convex surface with the aspheric surfaces of the pair of elements outermost. The pair of elements (14) is located between the two image planes formed in the telescope and is movable between two conjugate positions. | InventorsAssigneeApplicationNo. 694298 filed on 05/02/1991US Classes:359/354, Including continuously variable magnification or focal length (zoom lens, adjustable lens)359/356, Infrared lens359/357, Having four or more components359/676, With variable magnification (e.g., zoom type)359/679With fixed conjugatesField of Search359/353, Including alternative optical path or optical element (e.g., day-night, hi-low magnification)359/354, Including continuously variable magnification or focal length (zoom lens, adjustable lens)359/355, Lens, lens system or component359/356, Infrared lens359/357, Having four or more components359/676, With variable magnification (e.g., zoom type)359/679, With fixed conjugates359/684, Other than first group moves for focusing (internal focus type)359/691Two groupsExaminersPrimary: Arnold, Bruce Y.Assistant: Ryan, J. P. Attorney, Agent or FirmUS Patent References3890036, 4148548, Temperature compensating focusing in infrared zoom lensesIssued on: 04/10/1979 Inventor: Thompson4494819Telescope objective system for the infrared range Issued on: 01/22/1985 Inventor: Lidwell Foreign Patent References
International ClassG02B 015/00Foreign Application Priority Data1990-05-18 GB |
