Radiation beam scanning apparatus and method employing distortion compensation

摘要

Radiation beam scanning apparatus comprises a rotatable reflector for causing an incident radiation beam to undergo a scanning movement; and a compensating device on to which the radiation beam impinges before reaching the rotating reflector. The compensating device modifies the optical path of circumferentially spaced portions of the beam upstream of the reflector, in phase with the rotation of the reflector, so as to compensate for distortions in the reflected beam introduced by the reflector.