Zoom projection lens systems.

摘要

Zoom projection lens systems are provided which have 1) an entrance pupil which remains at a substantially fixed position as zooming takes place, and 2) an operative aperture stop, distinct from the system's physical aperture stop, which moves through lens surfaces as zooming takes place. The fixed entrance pupil allows for efficient coupling to a light source throughout the magnification range of the system. Methods which can be used to design and produce zoom lens systems of this type and which employ a pseudo-aperture stop are also disclosed. <IMAGE>