Measurement and Testing by Digital Speckle Correlation

摘要

Uses of digital correlation analysis of speckle intensities are described in measurements and monitoring of rough surfaces. First, theoretical relationships for correlation properties of speckle patterns are surveyed in terms of the intensity cross-correlation between two patterns. They consist of speckle displacement and decorrelation, each of which is related to the position and the reduction of correlation peak, respectively. For examples, speckle displacement is applied to measurement of strain by a laser-speckle strain gauge and a speckle extensometer both of which are perfectly non-contacting. Speckle decorrelation is used for the measurements of surface roughness and monitoring of paint drying process. Relationships with digital holography that enables to derive 3-d speckle cross-correlation are also mentioned.