Measurements of Amplitudes of Micro-Oscillations using a Microscope Light-Cut Technique

Abstract

IT has recently been shown by Tolansky¹ how the Schmaltz light-cut technique can be modified and developed such that magnification of × 2,000 with resolutions of 0.25 µ is obtainable. We have applied one of these modified methods to the measurement of the amplitudes of vibration of a 20-cm. Monel rod excited by the familiar magneto-striction methods. Tolansky and Bardsley² have already shown how the small amplitudes of vibration usually met with in quartz vibrators (ranges of the order of 50–5000 A.) can be measured interferometrically, but this is a relatively elaborate technique. The amplitudes which can safely be developed in a magneto-striction vibrator can well exceed several microns, and for measurements of such amplitudes, interferometry is neither necessary nor desirable in view of the simplicity of the high-resolution light-cut method already reported on by one of us.