METHOD AND SYSTEM FOR SHIFTING AT LEAST ONE LIGHT SPOT WITH A PHASE-MODULATOR

摘要

A system for shifting at least one light spot (103) relative to an information carrier (101) during data read - out. The system comprises a phase-modulator (706) comprising a layer of liquid crystal sandwiched between upper and lower substrates. A first set of electrodes (903a) is provided on the upper substrate, arranged in a first lateral shifting direction (x) and a second set of electrodes (903b) is provided on the lower substrate, arranged in a second lateral shifting direction, orthogonal to the first. A first voltage gradient is applied across the first set of electrodes (903a) and a second voltage gradient is applied across a second set of electrodes (903b) so as to generate first and second respective phase profiles for shifting the at least one light spot (103) in the respective first direction (x) and second direction (y) .