Application of Multiple-Beam Interferometry to the Study of Oscillating

Abstract

WE have succeeded in applying multiple-beam interference methods to the study of the surface movements of oscillating quartz crystals, and the striking results obtained indicate that this has opened up a considerable field for investigation. The technique is simple. The quartz crystal (kindly prepared for us by Dr. W. G. Radley of the Post Office Research Laboratory) was polished to a slightly higher degree than that usually adopted for oscillators, in order to give sharp interference fringes. It was silvered very lightly on one side, and on the opposite face with a high reflecting silver layer. The high reflecting face was placed resting in contact with a silvered optical flat, and electrical connexion made (by gentle contact) between the lightly silvered face of the crystal and the silver layer on the flat. The two connecting leads were taken to an oscillator circuit. There were no constraints on the crystal.