Reflective condensing system for concentrating illumination at an aperture

Claim 1

In an optical system for condensing light from a source and transmitting the same for emergence at an aperture, means forming a transversely unobstructed open ended light path, said light path being bounded throughout substantially the entire length of the path by only two flat front surface mirrors with said surfaces in opposed relationship whereby light directed in the entrant end of said path against one of said surfaces at an angle is reflected to said other into and then reflected back and forth between said surfaces to emerge as a concentrated beam at the exit end of said path, means mounting said front surface mirrors in spaced relationship and inclined towards each other in the direction toward the exit end of said path, means cooperating with said mounting means for setting the angle at which the mirrors are inclined toward each other to accommodate a particular light source, aperture means for engagement by a film at the exit end of said path, said aperture means being adjustable to provide apertures of different dimensions, and laterally enclosed transversely unobstructed passage means completing said path from the adjacent ends of said mirrors to said aperture means whereby no dirt can interfere with the even flooding of said film by light from said path.