Telecentric illumination scanning system

摘要

Optical apparatus that condenses illuminating light into a narrow formatted band of light that follows activated lines down a light valve (11) as it is driven. The present invention is a telecentric illumination scanning system (10) that comprises an input lens group (12), a rotatable or oscillating reflective scanner (16), an output lens group (14) and a polarizing element (17). The input lens group (12) transmits light provided by a light source (13) to the scanner (16), which is reflected therefrom and is directed to the output lens group (14). The light transmitted by the output lens group (14) is polarized by the polarizing element (17) and applied to the light valve (11). The input and output lens groups (12, 14) focus the light provided by the light source (13) into a relatively narrow band of light that is scanned by the rotatable or oscillating scanner (16) across the face of the light valve (11). A telecentric light zone (21) is formed in a predetermined space between the output lens group (14) and the light valve (11). Scanning is accomplished by varying the angle of the bundle of chief rays at the aperture stop. The scanned illumination may be synchronized with the imaging processes of the light valve (11). The present invention thus eliminates illumination from the areas of the light valve (11) that are not activated during or between video frames and greatly increases the light output and contrast of a light valve ype projector system (10).