ROLE OF LENS APERTURING IN SPECKLE METROLOGY

Use of multi-aperture screen placed in front of an imaging lens modifi es the speckle structure when using speckle phenomena for measurement. ; Consequently halo distribution during filtering stage is completely modified. Aperturing of the lens offers several advantages; recording of several information on the same plate and retrieval, and simultaneo us recording of both displacement and its derivatives. Components of d eformation vector can be separately recorded. Further the sensitivity and range for in-pane displacement measurement can be increased. The c ontrast of fringes is also enhanced.