APPARATUS FOR MAKING LAMINAR RADIOGRAMS

摘要

PHD 77-037 11-11-1977 In tomosynthesis distortions are produced owing to the curvature of the image intensifier input screen and other non-linearities of the transmission system, which in particular affect the synthesis of the laminar image when the individual images should be shifted relative to each other for this purpose. These distortions depend on the angle which the central ray makes with the laminar plane during the individual exposures and therefore they can hardly be compensated for. The invention now proposes that when the individual images are taken the image intensifier is steered so that the optical axis always remains parallel to the central ray. The distortions produced by the curvature of the input screen of the image intensifier etc. are then independent of the angle between the central ray and the laminar plane, and can be compensated for by known commercially available correction devices. However, additional geometric distortion is then produced because the plane of the input screen is inclined relative to the laminar plane. These geometric distortions depend on the orbit angle. By a rotation of the deflection field in accordance with the orbit angle, it is then achieved that trapezium distortions are produced which are independent of the orbit angle. These trapezium distortions are compensated for in known manner, and subsequently the position of the deflection field is restored.