| 摘要 |
PURPOSE:To obtain an optical recording medium which is capable of the accurate tracking and can be produced easily, by preparing a substrate containing an optical recording thin film and a substrate containing tracking grooves separately from each other, and then bonding these substrates together with the recording thin film and the tracking grooves set opposite to each other. CONSTITUTION:An optical recording medium is formed by laminating the 1st substrate 1 containing an optical recording thin film 2 and the 2nd substrate 2 containing tracking grooves 4 with the film 2 and the grooves 4 set opposite to each other. In this case, a shown equation (m=0, 1, 2) is satisfied (l: depth of groove 4; lambdaAngstrom : wavelength of beam; n: refractive index of substrate 2). At the same time, the same material is used for both substrates 1 and 2, and no change must be caused due to the difference of coefficients of thermal expansion for the positional relation between the groove 4 and the information signal in the recording and reproducing modes. Furthermore the gap areas formed by the grooves 4 are set at the atmospheric pressure or less, and the space between both substrates is set within the depth of focus. At the same time, the information signal is recorded to the film 2 at the gap areas of the grooves 4. As a result, the accurate tracking is possible. |
