Contrast and sensitivity of the vibration fringes in time-averaged electronic speckle-pattern interferometry: effect of variations of force level

Abstract

The time averaged frame subtraction technique is improved by subtracting two Bessel fringe patterns at two different force levels. The technique enables significant enhancement of fringe contrast and increased measurement sensitivity. The contrast and sensitivity of the fringes obtained at different force ratios are investigated. Both theoretical and experimental results are presented.