Temporal speckle pattern interferometry for measuring micron-order surface motion of a liquid bridge

Abstract

This paper presents a technique based on temporal speckle pattern interferometry (TSPI), a new version of electronic speckle pattern interferometry (ESPI), for measuring micron-order motion of a deformable surface of a quasi-cylindrical liquid bridge. The time sequence phase method (TSPM) proposed recently has been extended to develop automated and robust procedures for temporal phase recovering of specklegrams. The performance of the procedures is verified through computer simulations made in a range of parameters involved. The technique is implemented into a TSPI system utilizing a ground glass for generating speckles from non-speckled reference and object wavefronts. The validity and accuracy of the technique are examined in the measurement of dynamic displacement of both a flat mirror and a cylindrical glass rod, where detailed comparison is made with the simultaneous measurement taken with the laser focusing displacement meter. The capability of the present technique is demonstrated by some experimental results obtained from dynamic surface displacement of a liquid bridge of silicone oil.