Measurement Mark Profiles of Digital Versatile Disc and Multilevel Read-only Disc with Atomic Force Microscopy

摘要

This paper presents the profile measurement method for recording marks in signal waveform modulation multilevel (SWM) read-only disc. In SWM disc, multilevel is realized with the combined varying size and position of inserted sub-pit/sub-land in an original recording land/pit. The micro-patterns of the recording marks are key identifier for level of run-lengths. In mastering process, the mark profile is shaped with timing duration variation of the power of laser beam recorder (LBR). To form ideal SWM recording pit microstructure, atomic force microscope (AFM) is used to measure the pit profile, which is feedback and used to adjust the writing strategy. The measured parameters including depth, height and position, etc. 6T land and pit are selected as examples to describe the relationship between the variation of these parameters and levels of run-lengths. The recording symbol microstructures of DVD and signal amplitude modulation (SAM) multilevel optical disc are also measured with AFM, which are compared with the mark profile of SWM disc. The experimental results show that the AFM measurement for SWM recording marks is an effective method. These quantitative measurement results provide theoretical basis for SWM stamper disc manufacturing process.