Abstract: Surface tension is a physical quantity which characterizes the surface properties of liquid. Its measurement has important research significance in the fields of medicine, surface physics and so on. In this paper, a method of digital holography is proposed to realize the non-contact and high-precision measurement of liquid surface tension. Firstly, a lensless Fourier transform digital holographic device based on Mach Zehnder interference light path is built. The hologram taken by CCD is numerically reconstructed by inverse Fourier transform. The phase diagram is obtained by using the phase unwrapping algorithm of Fourier transform, and then the crosssectional profile of static droplets is obtained. The surface tension coefficient of liquid is obtained by fitting the droplet profile with the explicit and accurate solution of Yang-Laplace equation. The relative error of water surface tension coefficient at 20℃ is about 0.42%.

Key words: surface tension, digital holography, surface profile, Yang-Laplace equation