Abstract: An optical scanning system for projecting an image onto a moving surface comprises four reflecting surfaces, a first or scan reflecting surface to deflect an incident light ray into a first direction, second and third reflecting surfaces mutually at right angles which together reflect the ray from the first reflecting surface in a direction opposite to the first direction and displaced laterally therefrom, and a fourth or exit reflecting surface to receive the ray reflected from the third reflecting surface and to deflect it parallel to the incident ray onto the moving surface. The scan and exit reflecting surfaces are maintained at right angles to each other as they are translated in opposite directions during a full scan of the image.