Laser interferometric measurement of the surface tension of thin foils

Abstract

A technique has been developed to measure the surface tension of thin foils under their own vapor pressure. The zero creep method of surface tension measurement is used in conjunction with laser interferometry. This technique allows very small sample strains to be measured. Sample length changes of the order of 0.3 μm were measured with the laser interferometer. The sensitivity of the laser interferometer/zero creep system allows the surface tension to be measured much closer to the Tammann temperature, which is approximately one-half the melting temperature (≍1/2 Tm) of the material. The system has been tested on thin Sn foils in air, and on thin Al and Ni foils under their own vapor pressure (vacuum).