Method and device for measuring the tilt of an optical disc

摘要

A method and device for measuring the tilt in an optical disc drive ( 1 ) is disclosed. The optical disc drive ( 1 ) comprises two lasers ( 31, 41 ) generating two laser beams ( 32, 42 ) having mutually different optical characteristics. One of these laser beams ( 32 ) is continuously ON, and is used for writing or reading data to or form the disc. The other laser beam ( 42 ) is repeatedly switched ON and OFF. Tilt is measured by comparing a normalized error signal (RED(ON)) during the ON-phase (TON) with a normalized error signal (RED(OFF)) during the OFF-phase.