Multilayer Optical Disc Recording with Wavelength-Selective Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multilayer optical discs with position guides on each recording layer require complex pattern transfer processes, increasing costs and reducing yield, while existing solutions to address position deviations during recording and reproduction are inefficient, leading to potential track overlaps and reduced recording capacity.
Innovation Solution
A recording apparatus and method using a multilayer recording medium with a planar recording layer and a reference plane featuring a wavelength-selective reflective film, where the recording and servo laser lights have different wavelengths to prevent stray light and maintain a good signal-to-noise ratio, and employing an adjacent track servo (ATS) system to maintain track pitch and prevent overlaps during simultaneous recording of multiple spirals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a position guide is formed on each recording layer of a multilayer disc, then recording position control is improved, but manufacturing complexity and costs increase due to multiple pattern transfer processes
Solution Approach 1:
The invention extracts the position guide formation process from each individual recording layer and consolidates it to only the reference plane. This eliminates the need for multiple pattern transfer processes while maintaining recording position control through the use of a single position guide on the reference plane combined with wavelength-selective reflective films on intermediate layers.
Solution Approach 2:
The reference plane with its position guide serves a universal function for all recording layers. The single position guide on the reference plane provides positioning information for the entire multilayer structure, eliminating the need for layer-specific position guides and simplifying manufacturing.
2Manufacturing precision
If multiple pattern transfer processes are performed for multilayer disc manufacturing, then recording position accuracy is improved, but manufacturing costs and production time increase
Solution Approach 1:
The invention extracts and eliminates redundant pattern transfer processes by forming position guides only on the reference plane rather than on each recording layer. This reduces the number of manufacturing steps while maintaining positioning accuracy through the combined use of the reference plane position guide and wavelength-selective reflective films.
Solution Approach 2:
The position guide is formed preliminarily on the reference plane before the recording layers are stacked. This preliminary formation of the position guide eliminates the need for subsequent pattern transfer processes on each layer, streamlining the manufacturing workflow and improving productivity.
3Device complexity
If recording and servo laser lights have the same wavelength, then optical system simplicity is improved, but signal-to-noise ratio deteriorates due to stray light from the reflective film
Solution Approach 1:
The invention applies local quality by making the reflective film wavelength-selective rather than uniformly reflective across all wavelengths. The reflective film reflects only the servo laser wavelength while transmitting the recording laser wavelength, thereby preventing stray light interference and maintaining a high signal-to-noise ratio.
Solution Approach 2:
The invention changes the optical parameter of the reflective film from broadband reflection to wavelength-selective reflection. By adjusting the reflective film's properties to reflect only specific wavelengths, the system achieves both optical simplicity and high signal-to-noise ratio through spectral differentiation.
4Quantity of substance
If track pitch is reduced to increase recording capacity, then recording density is improved, but track overlap risk increases during simultaneous multi-spiral recording
Solution Approach 1:
The invention employs feedback through the adjacent track servo (ATS) mechanism that uses the position guide on the reference plane to continuously monitor and adjust the radial position of recording spots. This feedback system maintains accurate track positioning even when track pitch is reduced, preventing track overlap during simultaneous multi-spiral recording.
Solution Approach 2:
The invention replaces mechanical positioning methods with an optical feedback system. The ATS mechanism uses optical detection of the position guide and electronic feedback control to maintain precise track positioning, enabling reduced track pitch without increasing track overlap risk.
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
The solution reduces manufacturing costs, improves recording capacity, and enables efficient simultaneous recording and reproduction of multiple spirals without track overlaps, enhancing the recording rate and maintaining a high signal-to-noise ratio.
Implementation Method 1
a wavelength-selective reflective film, where the recording and servo laser lights have different wavelengths to prevent stray light and maintain a good signal-to-noise ratio
Data Source
AI summary
There is provided an recording apparatus including a light irradiation unit, a reference-plane tracking control unit, a recording unit that executes recording on the recording medium by independently modulating first and second recording beams when the recording beams radiated by the first and second objective lenses are designated as the first and second recording beams, respectively, a recording-layer tracking control unit that performs tracking control of the first objective lens based on reflected light of a first servo beam and tracking control of the second objective lens based on reflected light of a second servo beam when the servo beam radiated by the first objective lens is designated as the first servo beam and the servo beam radiated by the second objective lens is designated as the second servo beam, and a control unit that controls the reference-plane tracking control unit, the recording-layer tracking control unit, and the recording unit.