Uniform variable light source

Claim 1

A light apparatus comprising: first means having first and second ends defining therebetween a cavity for the passing of light, said cavity having an interior surface which uniformly and randomly reflects light entering said second end toward said first end; second means disposed at said first end for transmitting some of the light which is directed thereto through said cavity with the transmitted light having a luminance level which is uniform over substantially the entire area of said second means through which the light is transmitted, said second means reflecting some of the light which is directed thereto back into said cavity, said second means having glossless surfaces and uniform light transmission properties over substantially its entire surface at said second end; third means for providing a uniform distribution of luminous flux in a preselected distribution temperature range with substantially constant spectral chracteristics, said third means including a source of luminous flux which is uniform over a preselected area at a preselected distance from said source; and control means disposed between said first and third means for variably controlling the amount of the uniformly distributed luminous flux which is admitted from said third means to said first means through said second end to control the level of luminance which is transmitted through said second means over a substantial range without affecting the uniformity of the luminance level which is transmitted over substantially the entire area of said second means.