light valve

American  

noun

Electricity.

1. a light-transmitting device having transmissions that vary in accordance with an electric input, as voltage, current, or an electron beam, used chiefly for recording sound on motion-picture film.

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Etymology

Origin of light valve

First recorded in 1925–30

Example Sentences

He and two other engineers invented a computerized light valve monitoring system allowing all prints to maintain the picture quality of the original film.

From Forbes

It is possible to extend the limits considerably by using a light valve on a strong spring, but the valve still remains a limiting factor in the speed of the motor.

From Project Gutenberg

The mouth is placed against the aperture o, which fits closely round the lips, and the filtered air enters the mouth through a light valve v, which is lifted by the act of inhalation.

From Project Gutenberg