MIRROR YARDSTICK

E&MP 94.039

Photo Electric Cells

no date

Half the size of a dime, the tiny mirror at the left reflects a light beam into photo-electric cells to measure the amount of stretch of steel, caused by magneto-striction.

As the steel test piece (the light bottom sheet directly to the right of the mirror) lengthens, it rotates a small roller and mirror, causing the light beam to change its position on the photocell, a part of the anti-noise studies in the Westinghouse Research Laboratories.

PHOTO 250946

Original Caption by Science Service
^© Westinghouse