Velocity Measurement with Speckle and Speckle-like Photography

Abstract

The criteria for image structure and film properties for velocity measurement by speckle-pattern photography are discussed. Even with low intensity light sources, holographic film is unnecessary, and Plus-X-Pan film will record sufficient detail (in multiple exposures if necessary) to form diffraction pattern fringes. Speckle photography techniques can also be applied to appropriately prepared, incoherently illuminated surfaces, so long as the camera image has the correct speckle-like granular structure. Experiments verifying these ideas are described.

Speckle-pattern Velocimetry Applied to the Measurement of Zeta Potential

“…In a number of previous articles [1][2][3][4] we have discussed the application of multiple-exposure laser speckle-pattern photography to the measurement of velocity in slow flows (1 ums`-1 cms-1 ). We have recently applied the technique successfully to measure the velocity of micronsized colloidal mineral particles undergoing electrophoresis under known conditions.…”