Lichtstrahl-Ablenkvorrichtung

摘要

The invention relates to a light beam deflector consisting of a transparent deflecting prism (1) extending along an optical axis (3) and a carrier prism (2). The deflecting prism (1) has a light admission surface (5) substantially perpendicular to the optical axis (3) and a light emission surface (7). The carrier prism (2) is joined on the reflecting surface (4) to the deflecting prism (1), making the latter into a substantially symmetrical unit (1, 2) in relation to the optical axis (3) about which it is arranged to rotate. To reduce air turbulence when the unit (1, 2) is rotated, in front of the light admission surface (5) there is a hollow cylindrical component (11) fitted on the unit (1, 2), the axis of which substantially coincides with the optical axis (3) and the inside diameter of which corresponds at least to the diameter of the light beam (6) impinging on the light admission surface (5). The reduction in the air turbulence minimises positional errors in the deflected light beam (6'), so that, when the light beam deflector is used in an imaging device, uniform exposure and hence higher reproduction quality are attained.