Fabrication of a micro-Fresnel lens on a spherical substrate

Abstract

A decrease in the size and weight of the objective lens in an optical data storage system (ODS) would improve performance. Limits on reducing the lens size were investigated. Size reduction is limited by aberrations introduced by the disk cover plate that protects the recording medium from dust and scratches. Size reduction is also limited by off-axis aberrations introduced by beam tilt required to maintain a field of view similar to conventional ODS objectives. It was shown that a Fresnel microlens on a thin spherical shell is acomatic for all field angles. A technique used to fabricate such a lens was demonstrated. The resulting lens was presented.