Multilayer Optical Disc Modulation Correction
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Solution Overview
Problem
In multilayered optical discs, stray light from other layers affects the degree of modulation and reflectance, making it difficult to ensure compatibility among different optical disc devices, especially with increasing recording capacity and layer density, as existing solutions require replacing all measurement optical systems.
Innovation Solution
A method that measures the modulation degree and reflectance of each layer in a multilayered optical disc, then converts these values into a standard optical system, allowing for correct comparison and compatibility without the need for a special measurement optical system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the area of the light receiving section or the magnification of the detection system is increased to improve measurement sensitivity, then the amount of stray light from other layers increases, but the measurement precision deteriorates due to contamination from stray light
Solution Approach 1:
The patent measures the stray light amount from other layers and uses this harmful factor as correction data. By quantifying the stray light and applying correction based on measured values, the system converts the harmful stray light effect into useful correction information, enabling accurate modulation degree measurement even with increased light receiving area or magnification
Solution Approach 2:
The patent replaces physical optimization of the optical system (increasing light receiving area or magnification) with a computational correction approach. Instead of mechanically optimizing the measurement system to avoid stray light, the invention uses mathematical correction based on measured stray light amounts and optical system parameters to achieve accurate results
2Adaptability or versatility
If a standard optical system is established for measuring modulation degree and reflectance, then compatibility among different measurement systems improves, but the device complexity increases due to standardization requirements
Solution Approach 1:
The patent establishes a standard optical system defined by specific parameters (light receiving section area, magnification, numerical aperture). By standardizing these optical parameters and using them as the basis for correction calculations, the invention achieves compatibility across different measurement systems without requiring complete system replacement
Solution Approach 2:
The patent introduces a correction calculation as an intermediary process between different measurement systems. The correction based on stray light amount and optical parameters acts as a mediator that enables comparison and compatibility between systems with different configurations
3Quantity of substance
If the number of recording layers is increased to improve recording capacity, then the information storage capability increases, but the measurement precision deteriorates due to increased stray light from additional layers
Solution Approach 1:
The patent measures the stray light amount from other recording layers and uses this harmful effect as correction data. By quantifying the stray light contribution from each layer and applying correction, the system enables accurate modulation degree measurement even in multilayered discs with high recording capacity
Solution Approach 2:
The patent separates the measurement into components: the signal from the target layer and the stray light from other layers. By measuring and correcting the stray light component from other layers individually, the system can accurately determine the modulation degree of each layer in multilayered discs
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate comparison and compatibility of optical discs across different measurement systems, ensuring stable reproduction and compatibility among various optical disc devices by correcting for stray light effects.
Implementation Method 1
a laser beam having a wavelength in a range from 400 nm to 410 nm, specifically, a wavelength of 405 nm is collected by an objective lens having an NA (Numerical Aperture) in a range from 0.84 to 0.86
Implementation Method 2
When the pit or the record mark is reproduced by use of the light beam, a reproduction signal is generated
Data Source
AI summary
An optical information medium measurement method, for measuring a degree of modulation in an optical information medium of a multilayered structure having a plurality of information layers, includes a first step of measuring a modulation degree of each layer of the optical information medium, and a second step of obtaining a thickness between layers of the optical information medium. Further, the method includes a third step of obtaining a reflectance of each layer of the optical information medium, and a fourth step of converting the modulation degree of each layer, as measured in the first step, into a modulation degree at a reference optical system differing from the measurement optical system, based on a value indicative of the thickness between layers, the thickness being obtained in the second step, and a value indicative of the reflectance of each layer, as obtained in the third step.