Laser Power Adjustment via Squared Modulation Factor
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Solution Overview
Problem
Existing methods for adjusting laser power in optical recording media, such as the linear fit method, require multiple test writings and lengthy processing due to non-linear characteristics of modulation factors, making precise adjustment with a small number of tests impractical.
Innovation Solution
A method that linearly approximates the relationship between integrated values and laser power by using the square of the modulation factor, allowing for accurate laser power adjustment with fewer test writings by calculating the optimum laser power based on the power at which the modulation factor becomes zero, using the expression Pw=Pwth×{1+1/(γ+1)}.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the linear fit method is used for laser power adjustment, then laser power can be adjusted based on γ values, but multiple test writings and lengthy processing are required due to non-linear characteristics of modulation factors
Solution Approach 1:
The patent changes the parameter used for linear approximation from the conventional Sn=m(Pwn)×Pwn to Sn=m(Pwn)×Pwn². This parameter transformation makes the relational characteristics between integrated values and laser power linear, eliminating the need for multiple test writings and lengthy processing while maintaining accurate laser power adjustment.
2Measurement precision
If test writing is repeated many times to obtain accurate laser power, then measurement precision improves, but processing load increases and adjustment time lengthens
Solution Approach 1:
By transforming the parameter from Sn=m(Pwn)×Pwn to Sn=m(Pwn)×Pwn², the patent achieves linear relational characteristics that allow accurate laser power measurement with only two or three test writings, dramatically improving adjustment efficiency while maintaining measurement precision.
3Loss of time
If linear approximation is performed with around two or three Sn values, then processing time is reduced, but measurement precision deteriorates due to non-linear characteristics
Solution Approach 1:
The patent transforms the integrated value calculation to Sn=m(Pwn)×Pwn², which creates linear relational characteristics between integrated values and laser power. This allows accurate laser power calculation with minimal test writings (2-3 times) while maintaining high measurement precision, resolving the contradiction between speed and accuracy.
Data Source
AI summary
In order to set optimum laser power for a disk smoothly and appropriately with a small number of times of test writing, an integrated value Sn is obtained from each kind of laser power Pwn set for the test writing and the modulation factor m(Pwn) of a reflection light intensity obtained through the test writing with the laser power Pwn using an expression “Sn=m(Pwn)×Pwn2”, laser power Pwth is obtained at which the modulation factor m(Pwn) becomes zero when relational characteristics of the integrated value Sn and the laser power Pwn are linearly approximated, and optimum laser power Pw is set based on the laser power Pwth. Here, the optimum laser power Pw is obtained from the target γ value of the disk using an expression “Pw=Pwth×{1+1/(γ+1)}”. The target γ value is obtained from an ADIP of the disk.