Optical disk having lands and grooves with a reduced track pitch

摘要

An optical disk has grooves and lands located on the disk. A predetermined distance between the grooves and lands is defined as a predetermined track pitch. The predetermined track pitch is defined in term of a laser wavelength used during an operation. The grooves have a depth "d" in relation to the lands. The depth is related to a parameter variable "a" and a refraction index "n" of a substrate.