System for creating, reading and writing on rotatable information storage media, an apparatus for controlling vertical laser alignment

摘要

An apparatus is provided for varying the direction which a control laser beam impinges on a rotatable storage medium. The reflected control beam is thus modulated by surfaces aspects of the medium such as by embedded reference tracks. This reflected light signal is converted to an electrical signal which is analyzable to determine vertical alignment particularly with respect to the orthognal direction. In one embodiment, the apparatus comprises a rotating cylinder in which a lens is disposed in a canted orientation so that the optical axis of the lens is not exactly aligned with the axis of the cylinder about which rotation occurs.