Beam filtering device and method

摘要

A beam filtering device comprises a strip carrying at least one filter. The strip is wound onto drums between which the strip extends. A rotary drive mechanism drives the drums in rotation to cause the strip to advance and wind onto one drum while unwinding from the other. Advancing the strip makes it possible to arrange one of the filters on the strip in the space between the drums. This allows radiation filtering characteristics to be readily and rapidly modified.