| 摘要 |
PURPOSE:To assure good reproduced signals and tracking servo signals and to increase a storage capacity by varying the depth of optical phase bits adjacent in a tracking direction corresponding to a light beam for reproduction. CONSTITUTION:Two kinds of the optical phase bits 5 varying in depth are formed alternately adjacently to each other at an interval of 0.7mum distance between the centers of the bits on a substrate 1 consisting of a polycarbonate disk by an injection method. Reproduction of such a case is executed by rotating the disk at 1.2m/s line speed, condensing the continuous light of a reproducing light power of 0.5mw on the film surface by an objective lens having the numerical aperture NA of 0.5 in the optical head, irradiating a reflection film 2 with this light through the substrate 1 and detecting the reflected light. Bisected photocletectors are used in detecting the reflected light. The reproduced signal is obtd. from the sum signal of the photoelectric conversion output from the respective light receiving surfaces and the tracking servo error signal is obtd. from the differential signals. |
