Abstract: Anamorphic optics in a phase correlation autofocussing system modify the aspect ratio of separation images that are incident on a separation image signal conversion means such as a CCD array, thus enabling the autofocussing to be carried out with respect to a plurality of subjects at the extremes of a subject field.

Abstract: A method for assessing and correcting via feedback, the optical quality of an imaging device. The method has an advantage of expanding the applicability of a classical optical transfer function, heretofore a measure only of global imaging device performance, so that it can provide feedback information for correcting an imaging device defect in terms of local area modifications.

Abstract: A vacuum drum for securing and retaining different sizes of flexible sheet media has cylindrical surface holes connection different sets of longitudinal bores connected to right and left end radial bore distribution rings. The rings are adapted to be selectively separately connected to external sources of vacuum to provide first and second evacuation zones on the drum surface. A preferred embodiment has left and right shaft section ports connected so that application of a vacuum source to the left port evacuates a first drum zone for holding a smaller sized media, and connection of both left and right ports to a vacuum source evacuates both first and second drum zones for holding a larger media.