Optical Pick-Up and/or Recording Device
AssigneeKoninklijke Philips Electronics N.V.
InventorsFerry Zijp, Coen Adrianus Verschuren
Life of this patent
Estimating the term…
Abstract
For optical data storage applications a near field optical system can be used. In near field optical systems an accurate alignment of a solid immersion lens with respect to a disc surface is crucial. The correction of a tilt between the lens and the disc is performed by use of auxiliary beams. By comparing the gap signal for the auxiliary beams the air gap height and disc tilt can be determined.
Claims22
Optical pick-up and/or recording device (1), which optical pick-up and/or recording device comprises at least a lens element (11) adapted to focus at least two radiation beams on a storage medium (13), a moving mechanism (31, 36) adapted to vary an inclination of a front surface (12) of said lens element (11) relative to a surface (14) of said storage medium (13), a beam intensity measuring unit (25) adapted to measure at least indirectly an intensity of a first reflected radiation beam reflected at a gap between said lens element (11) and said storage medium (13) by frustrated total internal reflection and adapted to measure at least indirectly an intensity of at least a second reflected radiation beam reflected at said gap between said lens element (11) and said storage medium (13) by frustrated total internal refection, an inclination determination unit (26) adapted to determine an inclination between said front surface (12) of said lens element (11) and said surface (14) of said storage medium (13) on the basis of said intensity of said first reflected radiation beam measured by said beam intensity measuring unit (25) and said intensity of said second reflected radiation beam measured by said beam intensity measuring unit (25), a control unit (30) adapted to control said moving mechanism on the basis of said inclination between said first front surface (12) of said lens element (11) and said surface (14) of said storage medium (13) determined by said inclination determination unit (26) so that said front surface (12) of said lens element (11) is aligned with respect to said surface (14) of said storage medium (13).
Dependencies are inferred from the claim text.