Hybrid recording is one of the most promising candidates to breaking down the technical barrels of the extremely high density recording. To acquire the goal, the recording grains must get much smaller than ever before, and at the same time, the track pitch must also decrease from ~200nm to ~70nm. Thus the design margin for the tracking servo shrinks dramatically.
This paper tries to answer questions like these: is the existing scheme still work on the conditions of the hybrid recording? If not, what are the key elements of the novel one? How to design such a fine servo system? The main concern of designing a servo system is relevant to several key factors, such as recording density; mechanics; signal to noise ratio. Some parameters should be assumed. This paper anticipates the requirements of the hybrid recording, and some assumptions (including recording density, mechanical characteristics, SNR, etc) have been made. Then, the requirements that the servo system should be met can be calculated. Results show that a novel tracking servo system should be designed. Finally a novel servo scheme is presented.