Nano-motion actuator with large working distance for precise track following

The nano-motion actuator (NMA) had been designed for precise track following on a spin-stand which evaluated read and write performance of a high-density magnetic recording. A required specification of the original NMA was a resonance frequency of over 5 kHz and working distance of over 10 μm. However, according as industrial researches of the perpendicular magnetic recording progress, a phenomenon that is called WATER (Wide Area Track ERasure) should be evaluated on the spin-stand. Since required working distance to evaluate the WATER reaches to over 50 μm, an X–Y stage on the spin-stand was cooperated with the NMA, as usual. However, the piggyback system which combined the X–Y stage with the NMA could not observe the WATER phenomenon continuously on a disk medium. Therefore, a new NMA which had a large working distance of over 50 μm was required. The new NMA was designed and simulated several resonance modes by using 2D or 3D of EFM analysis. The new actuator called as NMA-k501 realized the working distance of 43.3 μm and the resonance frequency of 5.33 kHz with a mechanical damper. As wide servo bandwidth was reached to 2.75 kHz to apply a PID controller, clear and sharp step responses could be showed at a 1 and a 10 nm, respectively. Furthermore, when precise positioning stability was evaluated, the NMA-k501 was positioning within 0.101 nm at 3σ.