Optical Recording Medium Merged Interface Refractive Index Control
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Solution Overview
Problem
Existing optical information recording media face challenges in achieving high reproduction output due to the need for precise film thickness in interference-based methods and low signal strength from fluorescent light emission in non-interference methods, leading to increased manufacturing costs and poor signal-to-noise ratios.
Innovation Solution
An optical information recording medium with multiple recording layers and intermediate layers of different refractive indices, where the recording layer and intermediate layer are merged at the incident side interface, allowing for a gradual refractive index change, reducing reflection at the near-side interface and enhancing signal-to-noise ratio through controlled reflectivity at the far-side interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If interference effect is utilized to read out information, then reproduction output is improved, but manufacturing precision requirement increases
Solution Approach 1:
An intermediate layer with refractive index n2 is introduced between the substrate and the recording layer (refractive index n1). This intermediate layer acts as a mediator to control the reflectivity at the interface, enabling the reading beam to be reflected with appropriate intensity without requiring precise control of the recording layer thickness. The intermediate layer's refractive index is specifically designed to satisfy the condition (n2-n1)/(n2+n1) ≥ 0.06, which ensures sufficient reflectivity for high reproduction output while relaxing manufacturing precision requirements.
2Manufacturing precision
If fluorescent light emission is used for reading, then film thickness precision is reduced, but reproduction output decreases
Solution Approach 1:
The intermediate layer with refractive index n2 serves as an optical mediator that enhances the reflection of the reading beam at the interface between the recording layer and the intermediate layer. By controlling the refractive index relationship ((n2-n1)/(n2+n1) ≥ 0.06), the system achieves sufficient reflected light intensity for high reproduction output, thereby avoiding the need to rely on weak fluorescent light emission which would otherwise be required to tolerate variations in film thickness.
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 approach enables high signal-to-noise ratio information regeneration without requiring precise film thickness, reducing manufacturing costs and improving reproduction output compared to traditional methods, while allowing for a larger number of recording layers for increased storage capacity.
Implementation Method 1
a method for causing a recording material contained in the optical information recording medium to produce an optical change using a multi-photon absorption reaction such as two-photon absorption
Implementation Method 2
a reading beam (light irradiated for reading out information) is reflected at an interface between the recording layer and an adjacent intermediate layer disposed at a far side of the recording layer
Implementation Method 3
the recording layer and an intermediate layer disposed adjacent to the recording layer at an incident side from which the recording beam enters the recording layer are merged with each other at an interface therebetween, whereby a refractive index gradually changes at the interface
Data Source
AI summary
An optical information recording medium 10 comprises: a plurality of recording layers 14, each of which undergoes a change in a refractive index by irradiation with a recording beam; and at least one intermediate layer 15 provided between the plurality of recording layers 14. The recording layer 14 and the intermediate layer 15 have different refractive indices, and, among interfaces between the plurality of recording layers 14 and the at least one intermediate layer 15, a recording layer 14 and an intermediate layer 15 disposed adjacent to the recording layer 14 at an incident side from which the recording beam enters the recording layer 14 are merged with each other at an interface (near-side interface 19) therebetween, whereby a refractive index gradually changes at the interface.