Variable-Area Light-Valve Modulator

A variable-area modulator is described which employs a ribbon light valve as the basic modulating element. Double-width push-pull, variable-area sound track or standard width dulateral sound track may be recorded at will by inserting the appropriate light valve into the modulator. The light valve is registered in place in the modulator by indexing dowels and securely locked by means of lever-controlled clamping springs. — The light-valve ribbons are oriented so as to be parallel to the direction of motion of the film. The ribbon edges are projected at ten times magnification onto the film to define the amplitude co-ordinate of the recording image while the image height is determined by a narrow rectangular stop which is imaged onto the film at a 70:1 reduction in height by a cylindrical lens system. — The modulator is a completely self-contained unit embodying the basic components for the recording optical system, an optical system for rear projecting an enlarged image of the ribbon aperture onto a viewing screen, a photoelectric monitoring system, and an exposure meter.

Print ISSN

0097-5834

Published

1948-11

Content type

Original Research

DOI

10.5594/J11723