Design and Analysis of Replicated Solid Immersion Lens for Large Thickness Tolerance in Near-Field Recording

Abstract

We have designed a novel solid immersion lens (SIL) optical head to increase SIL thickness tolerance for the fabrication and assembly of a SIL optical head. We have applied an aspherical replicated lens to a general SIL optical head to improve SIL thickness tolerance more than that of a hemispherical SIL and to maintain as high a numerical aperture as a super-hemispherical SIL. By using an aspherical replicated lens, we were able to reduce the sensitivity to spherical aberration with respect to variations in the SIL thickness, which are the main cause of narrow SIL thickness tolerance. This SIL optical head design shows that the SIL thickness tolerance is larger than 30 µm and the numerical aperture is 1.88, which is as high as that for a super-hemispherical SIL.