ROLE OF LENS APERTURING IN SPECKLE METROLOGY

Use of multi-aperture screen placed in front of an imaging lens modifies 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 simultaneous recording of both displacement and its derivatives. Components of deformation vector can be separately recorded. Further the sensitivity and range for in-pane displacement measurement can be increased. The contrast of fringes is also enhanced.