| 摘要 |
An optical disc adapted for realtime writing and reading with light of a single predetermined wavelength comprises a heat-deformable recording layer (33) overlying a reflective support (30). In contrast with prior art real-time optical discs in which the optical properties and nominal thickness of the recording layer are selected to maximize the difference in amplitude of light reflected respectively from recorded and non-recorded regions on the disc surface, the optical disc of the invention comprises a recording layer in which the optical properties and nominal thickness are selected so that the phase difference in light reflected respectively from recorded and non-recorded regions is substantially maximized, and so that a substantial portion of incident light is reflected from both recorded and non-recorded regions, whereby the detection of such phase difference is facilitated. Whereas the prior art discs require, for optimum signal-to-noise ratio, that the pits be of a depth substantially equal to the recording layer thickness and that the readout beam be focused to a spot size smaller than the pit size, no such requirements are attendent the optical disc of the invention. Moreover, gradual bleaching of the dye-binder material does not adversely affect the signal-to-noise ratio of the readout signal. |
