| 摘要 |
PURPOSE:To control tracking accurately by specifying effective depth of a guide groove and a pit groove in a recording medium having the guide groove for tracking and the pit groove forming preformat. CONSTITUTION:Guide grooves G for tracking and a pit PL that form preformat are formed on one face of a transparent substrate 10A. The effective depth of guide grooves G is made to 0.075-0.20 times the wavelength of laser light for record reproducing in the substrate 10A. When the variation of the level of various signals is measured in changing the effective depth of pit PL groove within the range of 0-0.4 times the wavelength, tracking signals is made stable in the extent in which the depth of pit PL groove is 0.26-0.45 times the wavelength, and tracking signal errors can be detected in preformat within allowable error. Thus, accurate tracking control is made possible. |
