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United States Patent
(io) Patent No.: (45) Date of Patent:
US 7,397,604 B2 Jul. 8, 2008
(54) NARROW BANDPASS FILTER ASSEMBLIES FOR SOLAR TELESCOPES
(75) Inventor: Curtis Ross Hruska, 895 Colleen Dr., Windsor, CA (US) 95492
(73) Assignee: Curtis Ross Hruska, Windsor, CA (US)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 272 days.
(21) Appl.No.: 11/415,257
(22) Filed: Apr. 29, 2006
(65) Prior Publication Data
US 2007/0253063 Al Nov. 1, 2007
(51) Int. CI.
G02B 27/28 (2006.01)
(52) U.S. CI 359/498; 359/589; 359/260;
(58) Field of Classification Search None
See application file for complete search history.
(56) References Cited
U.S. PATENT DOCUMENTS
The invention relates to the combination of lower transmit tance etalons with higher transmittance filters, including use of a single circular polarizer with high efficiency and optical performance for its filtered polarization, to achieve necessary throughput of a narrow bandpass region. The lower transmittance etalons can be achieved by using lower transmittance solid-state etalon materials, or by control of the coatings on the etalon. Alternate configurations are described that reduce the optical assembly's footprint, and/or include additional filters to remove stray light. An innovative option to heat the etalon directly is disclosed to actively stabilize and maintain the etalon's bandpass.
20 Claims, 2 Drawing Sheets
J. A. Dobrowolski, Coatings and Filters, chapter in Handbook of
Optics, Walter Driscoll, editor, 1978, p. 8-81; pp. 8-84 to
8-85,McGraw-Hill Book Company, New York, NY.
Donald G. Carson, L. Dean Canfield, and Marshall L. Ogne, Final
Report: An Evaluation of Interference Fitlers for Hydrogen-alpha
Telescopes for the Apollo Telescope Mount, LMSC-680238, Nov. 1967, pp. 66-70, 73-76, Lockheed Missiles & Space Company. Edwin Hirsch, Photographing the Sun in H-Alpha, Astronomy magazine, Jan. 1978, pp. 37-39, AstroMedia Corp.
* cited by examiner