CONTRAST ENHANCEMENT OF ELECTRONIC SPECKLE PATTERN INTERFEROMETRY ADDITION FRINGES

The electronic speckle pattern interferometer in the double-pulse addi tion mode can be used to measure physical parameters in unstable envir onmental conditions. Owing to additive optical noise, however, the fri nge patterns obtained have poor contrast. Some methods that use subtra ction of addition double-pulsed fringe patterns improve fringe visibil ity but impose a limitation in measurement time ranges. To increase th is range, to be Limited by only the pulse separation, the contrast enh ancement of double-pulsed addition-fringe patterns with a spatial filt er based on local-standard-deviation measurements is investigated. Com puter simulations and experimental results are presented. (C) 1997 Opt ical Society of America.