An Aspheric Lens for Motion-Picture Projection

An aspheric lens is described which is designed to be added to the elliptical mirror-type projection optical system commonly used with carbon-arc light sources. The aspheric lens is designed to reduce the effects of the inherent foreshortening of those crater images formed by the outer zones of an elliptical mirror of large collection angle. Measurements using a sample aspheric lens with an f/2.25 mirror showed an increased uniformity of both screen color and brightness distribution at the expense of a reduction in light on the screen. The addition of the lens substantially reduced the variations in screen color that accompany changes in crater position. The aspheric lens can be combined with a faster mirror to give the same screen light as with a slower mirror alone, but with an improved color and brightness distribution.

Print ISSN

0898-0438

Published

1955-08

Content type

Original Research

DOI

10.5594/J11307