Multilayer Optical Recording Medium Servo Layer Reflectivity
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Solution Overview
Problem
The increasing number of recording layers in optical recording media leads to reduced reliability of servo signals due to increased distance between servo layers and recording layers, limiting recording capacity and causing laser light attenuation, making it difficult to efficiently guide laser light to rear recording layers.
Innovation Solution
A multilayer recording medium with servo layers made of high reflectance materials for specific wavelengths, allowing for efficient guidance of laser light to recording layers through the use of multiple light sources and optical systems that converge light at different wavelengths, ensuring reliable servo signals and reduced light attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of recording layers is increased to enhance recording capacity, then the recording capacity is improved, but the reliability of servo signals deteriorates due to increased distance between servo layers and recording layers
Solution Approach 1:
The patent divides the optical recording medium into multiple sets of layers, where each set contains a servo layer and multiple recording layers. This segmentation allows the system to maintain reliable servo signals within each set while increasing the total number of recording layers across multiple sets, thereby resolving the contradiction between recording capacity and servo signal reliability
Solution Approach 2:
The patent introduces a reflective layer positioned between the servo layer and recording layers to act as an intermediary. This reflective layer redirects laser light that would otherwise be lost, improving the signal strength and reliability for rear recording layers without requiring a reduction in the number of recording layers
2Reliability
If servo layers are formed at predetermined intervals to reduce the number of recording layers between them, then the reliability of servo signals is improved, but laser light attenuation increases making it difficult to reach rear recording layers
Solution Approach 1:
The reflective layer serves as a mediator that captures laser light reflected from intermediate layers and redirects it toward rear recording layers. This intermediary structure compensates for light attenuation without requiring reduced spacing between servo layers, maintaining both servo signal reliability and sufficient light intensity for deep-layer recording
Solution Approach 2:
The patent converts the harmful effect of light attenuation by using the reflective layer to capture and redirect otherwise wasted reflected light. This transforms the loss of light energy into a beneficial signal reinforcement mechanism that enables reliable recording on rear layers despite the presence of multiple intermediate layers
3Quantity of substance
If multi-photon absorbing material is used in recording layers, then the recording capacity is improved, but the requirement for precise laser light guidance to rear layers becomes more critical due to increased light attenuation
Solution Approach 1:
The reflective layer acts as an intermediary that simplifies the operation of laser light guidance by automatically redirecting light to rear recording layers. This reduces the complexity of precise alignment requirements when using multi-photon absorbing materials, as the reflective layer compensates for misalignment and light loss
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
This solution enhances the reliability of servo signals and improves the efficiency of laser light guidance to rear recording layers, allowing for increased recording capacity and stable recording and reproducing operations across multiple layers.
Implementation Method 1
the servo layer is made of a material having a high reflectance with respect to laser light having a third wavelength for generating a servo signal, and low reflectances with respect to the laser light having the first wavelength and the laser light having the second wavelength
Implementation Method 2
a recording/reproducing objective lens for converging the laser light having the first wavelength and the laser light having the second wavelength on the recording medium; a servo objective lens for converging the laser light having the third wavelength on the recording medium
Implementation Method 3
at least one recording layer on which information is recorded by multi-photon absorption
Data Source
AI summary
A recording medium includes at least one recording layer on which information is recorded by multi-photon absorption, and a servo layer disposed in a laminated direction with respect to the recording layer and having a track for guiding a beam spot of laser light having a first wavelength and a beam spot of laser light having a second wavelength along a scanning trajectory. The servo layer and the at least one recording layer constitute a set of layers, and a plurality of sets of layers is formed in the laminated direction. The servo layer is made of a material having a high reflectance with respect to laser light having a third wavelength for generating a servo signal, and low reflectances with respect to the laser light having the first wavelength and the laser light having the second wavelength.