Deformation and Rigid-Body-Motion Measurement by Multiple Interferometric Strain/Slope Rosettes

The multiple interferometric strain/slope rosette (Multi-ISSR) is a method extended from the interferometric strain/slope rosette (ISSR) to measure relative displacements of multiple strain gages and rigid-body-motion. The Multi-ISSR consists of more than three micro-indentations depressed onto a material surface. Upon laser beam illumination of the Multi-ISSR, light reflecting and diffracting from the Multi-ISSR indentations interfere to result in fringe patterns. The complicated patterns are analyzed to measure deformation and rigid-body-motion. Optical theory of the Multi-ISSR is developed and the governing equation for measuring deformation and rigid-body-motion is derived. Derivation of the general Multi-ISSR governing equation for the case of three indentations is presented and compared with the governing equation of the published ISSR.