Tolerance allocation and auto alignment algorithm of focusing unit for near field recording system

Abstract

A tolerance allocation and auto alignment algorithm for the optical head of the near-field recoding (NFR) system are presented. The optical head of the NFR system consists of a solid immersion lens (SIL) and an objective lens (OL). The effects of assembling and manufacturing tolerances of SIL and OL are simulated using CODE V. These analyses show that the tolerances are very tight. So we proposed to move the collimate lens (CL) back and forth to compensate and control these tolerances, especially in the optical axis direction. Also, we allocate the compound tolerance of decenter and tilt motions of the SIL and OL using the worst On worst analysis (WOW) model. In addition, to align SIL and OL under these tolerances, we propose an auto alignment algorithm between SIL and OL. The simulation results of the alignment algorithm are compared with the experimental results.