  The design and operating of a portable holographic interferometer for
residual stress analysis by creating a small scratch along with a new
mathematical algorithm of calculations are discussed. Preliminary data of the
stress investigations on aluminum and steel alloys have been obtained by the
automatic processing of the interference pattern using a notebook computer. A
phase-shift compensation technique in real-time reflection interferometry is
used to measure the out-of-plane stress release surface displacement
surrounding a small scratch (25 um depth and 0.5 mm width) in a plate with
residual stress of around 50 MPa. Comparison between theoretical models for a
rectangular and triangular shaped scratch with the experimental data are
presented.
