Compact optical zoom with extended depth of field through wavefront coding using a phase mask

摘要

Disclosed is a zoom lens comprising a variator lens group, a compensator lens group and a third lens group. Said compensator lens group is arranged to only partially compensate for movement of the variator group. In order to increase the depth of field, the zoom lens further comprises image enhancing means which implement wavefront coding and artefact reduction techniques. A preferred technique employs a cubic or a petal phase-mask. The compensator group may be fixed or, alternatively, its movement relative to the variator may be effected by a simple cam mechanism.