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Gap maintenance system using near-field optics and piezoelectric materials for near-field recording

In this paper, our aim is to develop a system that can not only maintain stable gap distance under 100nm but also compensate the tilting between a pick-up head and disk surface for near-field recording (NFR), which is known as a key technology for a next generation optical storage. Applying total internal reflection (TIR) to the air gap measurement, we design an optical sensor to measure the gap distances at three points. Stack and bimorph piezoelectric actuators are utilized for high precision control with nanometer resolution. To understand dynamic characteristics of the system, an analytical method for boundary coupled beam model is performed and verified by comparison with the results of the finite element method (FEM).