(a) Neutron beams irradiate the sample and are detected by a neutron detector. Residual stress is determined from the measured diffraction angle, 2θ. The measured volume is defined by an incident slit and a receiving radial collimator. The sample position is scanned step-by-step, and then, 3D-distributions of residual stress in the sample are obtained.
(b) The principle of X-ray stress measurement is the same as that with neutrons; however, X-rays diffract in the surface layer; therefore, the surface stresses are measured by X-rays.