Collimator arrangement for a beam of accelerated charged particles

Claim 1

A collimator arrangement, for an accelerated charged particle beam, comprising a first collimator system for partially intercepting said charged particle beam and a second collimator system associated with said first collimator system for intercepting the diffused particles of said beam and the secondary particles produced by said beam impinging upon said first collimator system, said collimator arrangement having an axi XY which is coincidental with the mean path of said beam; said first collimator system comprising four pairs of collimating elements each formed as a jaw, four movable supports, each of said movable supports respectively carrying a pair of said collimating elements thereof separated from each other along the axis XY, each said jaw facing another jaw, said movable supports being mechanically connected to one another and symmetrically disposed with respect to a plane containing said axis XY for movement of said facing jaws toward and away from each other, and said second collimator system comprising four support-rods each mechanically associated with one of said movable supports for movement therewith, each of said support-rods carrying at least an intermediate metal strip and a terminal metal strip fixed at the free end of said support-rod, the internal edge of each intermediate strip being set back in relation to the internal edge of the terminal strip carried by the same support-rod, said intermediate strips and terminal strips of each pair of support-rods being thinner in the XY axis direction than said jaws and respectively located opposite one another and symmetrically disposed with respect to a plane containing said axis XY.