Residual stress determination in surface treated alumina samples applying beam limiting masks

This paper deals with the implementation of a theoretically described method to determine residual stresses in real space directly by means of small gauge volumes. For this purpose, beam limiting masks were designed, manufactured, and investigated in first experiments. Image series taken with a position sensitive CCD camera demonstrate the ability to detect interferences from gauge volumes beneath the sample surface by defined slit geometries. The experiments show that due to the highly absorbing masks the amount of detectable photons is poor, and thus long exposure times are necessary to receive suitable data. For increasing measurement depths (altering masks) a decrease in the intensity can be detected which leads to the assumption that the diffracted photons originate from deeper regions in the material. A model was developed to simulate the diffraction conditions with different mask layouts and material properties. Modeling yields consistent results with experimental data, and thus provides a basis for further improvements of the experimental setup and the realization and assessment of residual stress measurements.