NEAR FIELD OPTICAL LENS-TO-CARRIER APPROACH

摘要

The present invention provides a near field optical scanning device and in particular a method of bringing a lens (24) of a near field optical scanning device from a remote position to a near field position (23) relative to the surface of a record carrier (11). The invention makes preferably use of image processing of aperture pupil images indicating the size of a gap between a Solid Immersion Lens (SIL) and the surface of the record carrier. Image analysis of the aperture pupil image allows to derive a control signal for an approach procedure for air gap distances in a range of micrometers. This allows for a fast, efficient, accurate and reliable approach procedure making use of varying velocities of a head movement. Moreover the invention allows to make use of a detection scheme for interference fringes evolving in the aperture pupil image that principally allow to alternatively generate a control signal for the approach procedure and to reduce image analysis to an analysis of the intensity of the a section of the aperture pupil image.