US 7,178,948 B2 Feb. 20, 2007
(54) LIGHT COLLECTION SYSTEM
(75) Inventor: Anurag Gupta, Corvallis, OR (US)
(73) Assignee: Hewlett-Packard Development
Company, L.P., Houston, TX (US)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 199 days.
(21) Appl. No.: 10/919,936
(22) Filed: Aug. 17, 2004
(65) Prior Publication Data
US 2006/0039153 Al Feb. 23, 2006
(51) Int. CI.
F21V 7/00 (2006.01)
(52) U.S. CI 362/298; 362/301; 362/560;
(58) Field of Classification Search 362/298,
362/300, 301, 302, 560; 359/853, 858, 859 See application file for complete search history.
(56) References Cited
U.S. PATENT DOCUMENTS
A light collection system includes a substantially elliptical first reflector that defines first and second focal points on an axis. The first reflector has an annular region that encompasses the first focal point. The annular region has a width W that is the distance of its projection onto the axis in a direction perpendicular to the axis and the width W is less than or equal to about V20 of a distance Df between the first and second focal points. A second reflector has an aperture through the second reflector on the axis. The second reflector is shaped and positioned to reflect electromagnetic radiation from the annular region on the first reflector back to the annular region for reflection to a different portion of the annular region and back to the aperture.
49 Claims, 12 Drawing Sheets