| 摘要 |
PURPOSE:To improve S/N and to stabilize tracking characteristic by working a guide layer to a prescribed pattern, forming an interference layer of a light transmissive material having the refractive index higher than the refractive index of a substrate and etching this material in a prescribed amt. CONSTITUTION:The guide layer 16 for tracking is formed of Al, Ta, etc., and is fixed continuously or discontinuously in spiral or other shapes on the interference layer 14. The interference layer 14 is formed of the light transmissive material, such as SiAlON or TiO2 having the refractive index (n) higher than the refractive index of the glass substrate 12. The film thickness D of the layer 14 is specified nearly to D=(lambda/4n)+M(lambda/2n) in relation to the etching amt. (d). In the formula, lambda denotes a reproducing light wavelength; M denotes an integer. As a result, multiple reflections are generated between the substrate 12 and the recording layer 18 and the max. Kerr effect enhancement and excellent S/N are exhibited; in addition, the decrease in the reflection signals of the layer 16 is prevented and the stable tracking characteristic is obtd. |
