Analysis on effect of external shock in near-field recording system

In this research, we confirm that a near-field recording (NFR) system, particularly a solid immersion lens-based NFR system, is so weak to the slightest external shock that we should solve this problem to realize NFR technology for a real product. For this, we first define the disturbances caused by the external shock as the displacement of a disc and an actuator. We modify a general NFR servo system to deal with these disturbances by applying a safety mode to a switch mode, which is one of the servo systems in general NFR. To protect a disc from a collision between the actuator and the disc, we add a protector to the cover of the actuator and show that the NFR system with the applied safety mode can avoid the collision between a SIL and the disc for a severe external shock, such as the amount of 240 G based on the results of simulations.