CONTRAST ENHANCEMENT OF PULSED ESPI ADDITION FRINGES

In this paper, the contrast enhancement produced by the subtraction of two sets of double pulse electronic speckle pattern interferometry (E SPI) addition fringes is investigated. It is shown that in most practi cal cases this process will produce a second set of interference fring es in addition to those which can be directly related to the vibration mode of interest. The formation of this second fringe pattern is expl ained by theory and computer simulation. Finally, the results are veri fied using an ESPI system with a pulsed Nd: YAG laser.