Optical wavefront modifier

Abstract

An optical wavefront modifier(27)is adapted for modifying a wavefront of an optical beam passing through the modifier. The modifier comprises a first and a second transparent electrode layer(42, 43)and a flat medium(46)for modifying the wavefront in dependence on electrical excitation of the medium and arranged between the electrode layers. The electrode layers are adapted to impress a first wavefront modification of a first order of a radius in the cross-section of the beam in the plane of the medium and to impress simultaneously a second wavefront modification of a second order of the radius different from the first order.

Description

technical field [0001] The invention belongs to the field of optical reading and optical recording, and in particular relates to an optical wavefront adjuster, which is used to modify the wavefront of the light beam passing through the adjuster. The invention also relates to a device for scanning an optical record carrier having an information layer. [0002] Optical wavefront modifiers are used to modify the wavefront shape of a beam by introducing different optical path lengths depending on the location of the beam cross section. It can be used to change properties of a beam such as vergence by introducing a focus curvature in the beam's wavefront or by introducing tilt to change the beam's direction. The wavefront adjuster can also be used as a wavefront compensator to compensate for the unideal shape of the beam wavefront, for example to eliminate spherical aberration or coma aberration of the wavefront. Background technique [0003] European Patent Application No. 074...

AI Technical Summary

Problems solved by technology

A disadvantage of this known wavefront modulator is that aberration compensation cannot be performed accurately when the beam follows a track on the record carrier

Images