SUBSTRATE FOR OPTICAL MEMORY ELEMENT

摘要

PURPOSE:To largely assure the amplitude of address signal waveforms by forming guide groove parts having a specified groove width and auxiliary guide groove parts having a larger groove width to the grooves for forming either of guide tracks and recording tracks. CONSTITUTION:The plural grooves 21... which serve as the guide tracks are concentrically formed on the surface of the substrate 20 made of glass or plastic. The guide groove parts 23 having the specified groove width and the auxiliary guide groove parts 22... having the large groove width are so formed as to have the groove shapes continuous in the longitudinal direction of the grooves. The recording tracks 24... are formed of the shapes of the groove parts 23... and the groove parts 22... between the grooves 21.... The function similar to the function attained when pits are formed is thereby obtd. and the generation of distortion in the address signal waveforms is obviated even if the groove parts 22... are formed long in the longitudinal direction of the grooves. The degradation in diffraction efficiency is thus obviated and the large amplitude of the address signal waveforms is assured even if the groove parts 22... are formed in proximity to each other.