Abstract: In the illustrated embodiment, the light source utilized to mark the x-ray beam is a halogen lamp with a small focus, an optical lens system being provided for concentrating the light beam on an operative portion of a light reflective mirror so as to amplify the light intensity of the beam reflected by the mirror and lying within the fully opened pairs of x-ray opaque plates. The mirror is shown disposed at approximately 45.degree. diagonally relative to the collimator longitudinal axis with the axis of the light source and optical system extending approximately perpendicularly to the collimator longitudinal axis. The mirror is located between sets of close-to-focus plates and sets of remote-from-focus plates so as to provide a reflected diverging light beam of frusto-pyramidal configuration conforming with the pyrmidal beam shape for x-ray energy defined by the sets of plates.

Abstract: In the illustrated embodiment sets of four diaphragm plates are utilized to define the margins of a beam path configuration having the shape of a four-sided pyramid with its vertex coinciding with the focus of the x-ray tube. Each set of four diaphragm plates is mounted by means of levers which are capable of being pivoted in a scissors-like fashion so as to adjust the angle of divergence of the x-ray beam with respect to a given plane. For actuating the levers, a motor driven cam is coupled with the levers via a roller and a pair of links, a tension spring urging the levers in a direction so as to press the roller into following relation to the cam surface.