Abstract: Apparatus for reading optically a scene made up of symbols on a transparent medium comprises a transparent flat plate on which the scene is supported. An illumination system on one side of this plate illuminates at least part of the scene. An optical reader device on the opposite side of the plate incorporates an optical sensor. A pneumatic skid is moved over the opposite side of the plate and has a recess in its surface facing the plate in which the sensor is accommodated. Thus the scene is scanned by the sensor as the skid is moved over the plate.