A light beam deflection unit is formed of a light-transmissive deflection prism extending in the direction of an optical axis and of a carrier prism. The deflection prism has a light entry face oriented essentially perpendicular to the optical axis, a reflection face proceeding obliquely relative to the optical axis and a light exit face. The carrier prism is joined to the deflection prism at the reflection face and supplements the latter to form a composite unit essentially symmetrical relative to the optical axis that is seated rotatable around the optical axis. For the purpose of reducing air turbulence upon rotation of the composite unit, a hollow-cylindrical element whose cylinder axis essentially coincides with the optical axis and whose inside diameter at least corresponds to the diameter of the light beam incident onto the light entry face and that is connected to the composite unit is arranged in front of the light entry face. Position errors of the deflected light beam are minimized due to the reduction of air turbulence, as a result whereof a uniform exposing and, thus, a high reproduction quality are achieved given employment of the light beam deflection unit in a recording apparatus.