Physically optimized optical disc structure, method and apparatus

DETAILED DESCRIPTION The present invention provides structures, methods and apparatus which are useful both in coping with demanding real-time applications of the type mentioned above and in decreasing such materials related noise.
Thus, one object of the present invention is to provide a real-time optical disc approach that has improved writing sensitivity and reading signal contrast.
An additional advantage of the present invention is increased immunity to certain materials-related noise sources.
Such improvements and advantages are attained in accordance with one aspect of the present invention by providing a heat-deformable optical disc of the reflective read-out type which, with respect to a chosen reading light wavelength, is optimized in recording stratum thickness and optical constants (e.
g.
, refractive index and absorption parameters) for high sensitivity real-time writing and for high-contrast, phase shift reading.
In accordance with another aspect of the present invention, such a disc is further optimized in thickness and optical constants with respect to the chosen writing wavelength to further enhance writing sensitivity, thus reducing the required writing power.