High spatial resolution strain measurements within bulk materials by slit-imaging

High energy synchrotron radiation is employed for residual strain measurements from local gauge volumes within the bulk of polycrystalline materials. The longitudinal spatial resolution is defined by placing a narrow imaging slit behind the sample and recording the intensity distribution on a position sensitive detector. It is shown that the sample to slit distance can be increased without sacrificing longitudinal resolution by applying a reconstruction technique. Hence, space is provided for large samples and sample environments. The reconstruction technique is described and validated by measuring the residual strain profile of a shot-peened Al sample. A longitudinal gauge length of 95 mu m is achieved at 52 keV with a sample to slit distance of 10 cm.