Astigmatism correction in laser diodes.

摘要

Correction of the astigmatism of a diode laser (2) beam is achieved by utilizing the inherent nature of anamorphic optics (8) to produce astigmatism when decollimated light enters the anamorphic optics, in conjunction with a point diffraction interferometer which provides an observable interference fringe pattern between a plano transmitted wavefront and a diffracted spherical reference wavefront. The shape of the interference fringe pattern movement of the collimating lens (6) along the optic axis (Z), so that light entering the anamorphic optics is now decollimated, permitting the collimating lens to be positioned at a point where the anamorphic optics provides a degree of astigmatism that substantially compensates for the astigmatism of the laser beam. Since optical disc drives are inherently much more sensitive to astigmatism errors than to decollimation, the trade-off in optical quality is acceptable.