Patent ID: 7440370
Filing Date: 2008-10-21
Classification: G03G,G11B

Abstract:
1. A method for determining a read power of a laser beam to be irradiated onto an optical recording disc comprising a multi-layered body formed by forming a decomposition reaction layer containing noble metal oxide as a primary component and a light absorption layer so as to sandwich at least a dielectric layer therebetween and reproduce data recorded in the optical recording disc by forming a recording mark train including at least one of a recording mark having a length shorter than a resolution limit and a blank region having a length shorter than the resolution limit therein, which method for determining a read power of a laser beam comprises a first step of setting a power of the laser beam to a recommended recording power determined in advance, irradiating the laser beam whose power is set to the recommended recording power onto the optical recording disc and forming a recording mark train including at least one of a recording mark having a length shorter than a resolution limit and a blank region having a length shorter than the resolution limit, thereby recording test data therein, a second step of setting a power of the laser beam to a recommended read power determined in advance, irradiating the laser beam whose power is set to the recommended read power onto the optical recording disc and reproducing the test data recorded in the optical recording disc, a third step of judging whether or not signal characteristics of a reproduced signal obtained by reproducing the test data satisfies reference conditions, and a fourth step of changing the power of the laser beam for reproducing the test data when the signal characteristics of the reproduced signal do not satisfy the reference conditions and determining the power of the laser beam as an optimum read power when the signal characteristics of the reproduced signal satisfy the reference conditions.