NANOSCALE RESOLUTION LENS AXICON FOR HIGH DENSITY OPTICAL RECORDING USING KRYPTON ION LASER

K. B. Rajesh (India), P. M. Anbarasan (India) and K. Tamilmaran (India)

Received May 1, 2008

Abstract

It is observed that the low NA of the fiber ended lens limits the recording density and demands an integrated Solid Immersion Lens (SIL), however, achieving a comparable depth (z) resolution has required a precise mechanical dynamic focusing system. Hence a design to generate diffraction free beam (DFB) using lens with spherical aberration (axilens) is proposed for high density optical recording. The calculated results show that the proposed system achieves nano scale resolution, and can generate an adjustable depth of field along the propagation (z) direction. The nano scale resolution increases the recording area density over the fiber ended lens system (spot resolution of ~1mm). The large Depth of Focus (DOF) of axicon lens avoids the mechanical damage of the lens surface due to its friction with the spinning disk and helps to integrate other components easily with the system.

Keywords and phrases: optical recording, numerical aperture (NA), solid immersion lens (SIL), diffraction free beam (DFB), lens axicon.