Abstract A simplified optical apparatus for reflection-mode Digital Gradient Sensing methodology (r-DGS) to perform full-field measurement of surface slopes is proposed. It eliminates the need for a beam splitter to… Click to show full abstract
Abstract A simplified optical apparatus for reflection-mode Digital Gradient Sensing methodology (r-DGS) to perform full-field measurement of surface slopes is proposed. It eliminates the need for a beam splitter to record random speckles off a target and via the specular specimen normally. Instead, the target plane speckles reflected off the specimen surface are directly recorded at a known inclined angle. The simplification results in a highly efficient optical arrangement in terms of light loss intrinsic to the original apparatus that used a beam splitter. The simplified apparatus, however, requires altering the governing equations while interpreting the correlated speckle fields in the reference and deformed states. The details of these issues as well as successful demonstrations of simplified r-DGS to measure deflection of thin Si wafer subjected to flexure is reported. The modified approach is also demonstrated to study crack-tip deformations near an edge crack in a beam.
               
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