Hewlett-packard Company

Robert C Gardner

George Edward Smith

David E Silverglate

Greg P Smestad

Cheryl L McLeod

John F Snyder

Greg Perry Smestad

A lamp has a reflective cup with a light emitting device in the bottom of the cup. A transparent material having an index of refraction n fills the cup and extends to a hemispherical surface with radius R and an equator parallel to the opening of the cup. The reflective walls of the cup project substantially all of the light within a cutoff cone having an included half angle equal to the Brewster's angle of the transparent material. The center of the hemispherical lens surface is spaced from the rim of the opening of the cup a distance R/n. Thus, the opening of the cup is the locus of aplanatic points of the equator if the hemisphere. Most rays from within the cup are incident on the hemispherical lens surface at no more than the complement of the Brewster's angle. Thus, minimal light losses occur at the interface between the transparent medium and air. An aplanatic image is formed outside the hemispherical lens of a virtual source comprising a hemispherical surface extending through the rim of the cup opening. Such optics may also be used for a light accepting device. These principles may also be applicable to a an elongated cavity with a semicylindrical lens of radius R and edges spaced from the edge of the cavity a distance R/n.

High efficiency lamp or light accepter

The principles of non-imaging optics, rather than imaging optics, are used to provide a high power LED illumination lamp that has a specified limited viewing angle. A compound parabolic flux extractor extracts and concentrates light emitted by an LED chip and a light pipe continues the concentration into the specified viewing angle. A lens or a diffusant may be used to modify the light output of the lamp. A light constructed as an array of the lamps is suitable for use as an automobile external light such as a center high mounted stop light.

Nonimaging light source

Growing community of inventors

San Jose, CA, United States of America

Robert C Gardner