Patent GB-634152-A (GB)
Title: Improvements in the art of radiography
IPC: G03B42/02
Filed: 1945-11-21
Abstract: 634,152. X-ray apparatus. LASSUS ST. GENIES, A. H. J. DE. Nov. 21, 1945, No. 31330. Convention date, Sept. 11, 1944. [Class 98 (i)] Multiple-aspect radiographs on a single exposure area capable of giving an illusion of relief are produced by arranging the object between an X-ray tube and an assembly comprising a surface sensitized to X-rays and a covering X-ray line screen which has its opaque portions of greater width than its transparent portions, and, the object remaining stationary, displacing the X-ray tube and the said assembly along rectilinear paths in opposite directions, the amplitudes of the two displacements with reference to the point searched in the body being homothetically related. As shown, the X-ray tube S and the assembly comprising a radiographic plate P and an X-ray line-screen Z spaced from the emulsion I on the plate by a distance # are homothetically displaced through distances L, E about the point C searched. For viewing the radiographs thus obtained the negative, or a positive print on film which has been placed face downwards to reverse it left for right, may be covered with an optical linescreen of the same pitch and thickness as the recording screen, from which it may be obtained by contact-printing with X-rays, or the opaque portions may be of reduced width to allow the passage of more light through the screen; or with a lenticular screen of the same pitch having its optical centre spaced from the radiograph by the distance e. In the case of radiographs obtained with the screen T in close contact with the plate P, the recording being made by sliding the screen across the plate in the same direction as the plate moves by an amount equal to one grid interval p, the screen employed for viewing has a smaller interval p<SP>1</SP> than the taking screen defined by p<SP>1</SP>/p=(h-e)/h, , where e is distance between the radiograph and the viewing screen. The Specification as open to inspection under Sect. 91 comprises also two further recording methods and three constructions of X-ray linescreens. Instead of moving the tube S about the point searched, it may remain stationary and the screen and plate alone may be displaced a distance E, or in the case of radiographing a thin object, e.g. a hand, this may be placed in contact with the holder for the screen and plate which remains stationary while the tube S is displaced a distance L+E. Grooves may be formed in the rear face of a plate T, Fig. 4 (Cancelled), by machining, casting or moulding, and bars G of X-ray opaque material drawn to the chosen trapezoidal cross-section are inserted into these grooves. To secure the bars in place, the front face of the plate may have a set of parallel grooves R disposed at right angles to the bar grooves and of such depth that the bar tops project into the grooves R, the tops of the bars being bent over, preferably in opposite directions in alternate grooves R to grip the plate. The screen Z may be supported at a distance e from the emulsion I of the sensitive plate P either by a separate spacing frame or by the thickness of the plate P. Alternatively the plate J may be provided with an integral spacing strip as by casting the plate around the bars while these are supported on a temporary frame. This subject-matter does not appear in the Specification as accepted.