A novel tracking servo system for multi-types of DVD with phase-shift DPP method

Various kinds of DVD such as DVD-R/RW, +R/RW and -RAM (2.6 GB and 4.7 GB) are on the market and some next generation optical disks such as Blu-Ray disk are set to appear in the near future. The development of a read/write pick-up for the various kinds of disk is thus expected. In this paper, we propose a new tracking servo system named phase-shift differential push-pull (PS-DPP) method which is not dependent on track pitch and the position of the sub-beams. This system is applicable for all kinds of DVD. This paper describes the concept of PS-DPP, the design of the new inclined multidivision phase-shift grating, and the simulated and the experimental results of its push-pull offset compensation effect.