Abstract: The invention relates to a computed tomography method in which a conical radiation beam traverses an examination zone during a helical relative motion between the radiation beam and the examination zone. The reconstruction is performed by means of filtered backprojection, the filtering operations involving measured values resulting from different projections of voxels from at least approximately the same surface within the examination zone.

Abstract: Method of verifying the authenticity of a security document (1), the security document including a first at least partially transparent portion (7, 8) and an optical projection element (9) within or superposed with the first at least partially transparent portion (7, 8), the optical projection element (9) acting to transform a light beam (10a) passing from a light beam source through said first at least partially transparent portion (7, 8) into a patterned beam (11) of selected design, the method including the steps of: positioning the security document such that the light beam is transmitted through the first at least partially transparent portion and the patterned beam is projected onto a viewing surface (14), and verifying the presence of a patterned image by the impingement of the patterned beam on the viewing surface (14).

Abstract: A position measuring system for determining the relative position of a first object and a second object movable relative to one another that includes an incremental track, associated with a first object and having a periodic line structure that has individual lines and a scanning unit, associated with a second object movable relative to the first object, that scans said periodic line structure and that generates a corresponding incremental signal. A sensor system that generates absolute position information pertaining to the relative position of the first and second objects, wherein the width of the individual lines, as measured along a longitudinal direction of the incremental track, varies over at least a portion of the breadth of the incremental track, as measured in a direction transverse to the longitudinal direction, in such a way that a structure with absolute position information is superimposed on the periodic line structure.

Abstract: An X-ray apparatus includes an X-ray source for producing a beam of X-rays, an X-ray detector for detecting this radiation, and an X-ray filter with filter elements which is arranged between the X-ray source and the X-ray detector so as to attenuate the X-ray beam in each independent filter element individually. Each filter element can contain a liquid filling (22) which is electrically conductive and X-ray absorbing, the value of the X-ray absorptivity of each filter element being discretely adjustable by step-wise adjustment of the level of the liquid filling within each filter element. Each filter element includes an electrode (23) which is positioned between an isolator layer (34) and a substrate (38) in a wall of the filter element in order to apply an electric potential to the wall of this element. Another electric potential is applied to the liquid filling. Therefore, an electric capacitance can be defined per unit of surface area of the filter element.

Abstract: A step up transformer has an inert core, primary windings concentrically surrounding the inert core, and secondary windings concentrically surrounding the primary windings, the ratio of secondary windings to primary windings of up to 1,000,000:1. The step-up transformer is particularly useful in an x-ray catheter having an x-ray source in a vacuum tube and a power source. The power source can deliver a lower voltage which is stepped up at by the transformer to produce a voltage sufficient to stimulate production of x-rays by the x-ray emitter source. Methods for preparing the step-up transformer and x-ray catheter and methods of administering x-rays to subjects with the x-ray catheter of the invention are also disclosed.