Abstract: Means for locating accurately without ambiguity tomodensitometric sections sloping in any way with respect to an original predetermined plane. At least one locating element is disposed on the part to be examined by conventional tomodensitometry, this element having a baseline situated in the original plane and having at least one characteristic such as density, varying continuously or substantially continuously along a direction perpendicular to this baseline, the variation of this characteristic being measurable on the tomodensitometric images of the different sections; this characteristic may be in particular a dimension of the element: width perpendicular to the direction perpendicular to the base in the case where the element is a triangle.

Abstract: An apparatus for measuring stress on the surface of a polycristalline body X-ray diffraction including an X-ray source assembled together with two position-sensitive radiation detectors of known type located symmetrically with respect to the primary X-ray beam emitted by said source. The diffracted radiation gives rise to gaseous discharges within said detectors, which deliver signals respectively indicating the location of the ionizing event along their collector electrodes. From these locations along the collector, it is possible to determine the interplanar spacing d of the crystal lattice, which varies with the stress it is subjected to.