Improvements in or relating to scanning lens systems for electrostatic copying machines

The invention relates to electrostatographic copiers and in a first embodiment an optical arrangement is provided in which the image of an original placed on a part-cylindrical platen is reflected via a first mirror through a movable scanning lens onto a second, rotating mirror and thence onto a photoconductive surface of a drum. The platen may be either cylindrical or flat and have the image of the original reflected from a first mirror which is so inclined and dimensioned that substantially the whole of the perpendicular projection of the original falls on the first mirror, the arrangement being such that the optical path length between the original and the drum surface is maintained substantially constant.