Patent ID: 6717895
Filing Date: 2004-04-06
Classification: G11B

Abstract:
A method for determining an optimal modifying power for an optical record carrier, comprising:providing a record carrier with optical properties that can be changed between a written state and a different erased state and capable of being written by locally heating the record carrier with radiation pulses having an write power resulting in the optical properties of the record carrier being in the written state and being erasable by radiation pulses having a different erase power resulting in the optical properties being in the erased state, and wherein at least test marks on the record carrier are in the written state; determining a minimum modifying power (Pmin) of the radiation pulses, at which the change in the optical properties of the record carrier at the test marks is not substantial when the record carrier is irradiated at a power which is lower than the minimum modifying power, and the change in the optical properties of the record carrier at the test marks is substantial when the record carrier is irradiated at a power which is higher than the minimum modifying power; determining a maximum modifying power (Pmax) of the radiation pulses, at which the change in optical properties of the record carrier at the test marks is substantially maximal when the record carrier is irradiated at the maximum modifying power at the test marks; determining the optimal modifying power (PM) from the equation PM=Ï‡&CenterDot;(Pmin+Pmax)Î±in which &agr; is a predetermined constant for record carriers and &khgr; is a variable which is dependent on optical properties of the record carrier.