The development of a laser grating method for the measurement of strain distributions in plane, opaque surfaces

The laser grating technique for assessing strain distributions on plane opaque surfaces involves production of glass-plate negatives of grids affixed to specimens and reading of the negatives with a laser and optoelectronic devices that measure diffraction. The laser grating method has been applied to a study of strain distribution in front of an artificial crack in a thin sheet. Nonuniform straining of the fibrous grid material and deformation of the photographic emulsion on the glass plates during the development procedure have proven to be the chief sources of error in the laser grating assessments.