Patent ID: 8770800
Filing Date: 2014-07-08
Classification: F21K,F21V,F21Y

Abstract:
1. An apparatus comprising: an LED based illumination device operable to emit light in a Lambertian pattern over a surface of an output window; and an optical element coupled to receive the light emitted from the output window of the LED based illumination device, the optical element having an input port and an output port, wherein a perimeter of the optical element increases in size from the input port to a maximum perimeter, the optical element comprising: a hollow shell reflector having a first height; a first annular shell element having a first radius and a second height that is less than the first height, the first annular shell element disposed within the hollow shell reflector; and a second annular shell element having a second radius and a third height, the second annular shell element disposed within the hollow shell reflector at a location closer to the input port of the optical element than a location of the first annular shell element, wherein the second radius is less than the first radius.