Volume Hologram Recording Medium Moisture Absorption
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Solution Overview
Problem
Volume hologram optical recording media face challenges with moisture absorption, leading to reduced storage stability and archival life due to the resin matrix's tendency to absorb moisture, causing refractive index changes and affecting optical quality.
Innovation Solution
A volume hologram optical recording medium with a recording layer having a moisture absorption rate of 1.5 wt% or less is achieved by incorporating a resin matrix and photosensitive compound, where the resin matrix is formed by reacting polyisocyanates and polyols with specific functional groups, and an epoxy compound with multiple epoxy groups, along with a curing agent, to reduce hydrophilic functional groups and incorporate hydrophobic additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resin matrix with photosensitive compound is used for volume hologram recording, then recording sensitivity and diffraction efficiency are improved, but moisture absorption increases leading to reduced storage stability
Solution Approach 1:
The patent uses a composite resin matrix system comprising polyester resin, polyurethane resin, and epoxy resin in specific proportions (polyester: 30-70 wt%, polyurethane: 10-50 wt%, epoxy: 5-20 wt%). This composite approach combines the advantages of each resin type while minimizing their individual drawbacks, particularly moisture absorption, while maintaining high recording sensitivity and archival stability.
Solution Approach 2:
The patent modifies the chemical composition parameters of the resin matrix by incorporating specific ratios of different resin types and adding hydrophobic additives. This parameter optimization reduces the hydrophilic character of the matrix, lowering moisture absorption from typical levels to 1.5 wt% or less, thereby improving storage stability without sacrificing recording performance.
2Productivity
If hydrophilic functional groups are present in the resin matrix to enhance photosensitivity, then recording performance improves, but moisture absorption increases reducing archival life
Solution Approach 1:
The patent carefully controls the concentration and type of hydrophilic functional groups in the resin matrix by selecting specific polyester, polyurethane, and epoxy resins with balanced properties. This parameter optimization maintains sufficient photosensitivity for high-quality recording while limiting moisture absorption to 1.5 wt% or less, thereby extending archival life.
Solution Approach 2:
The patent introduces hydrophobic additives as intermediary substances that modify the overall character of the resin matrix. These additives act as mediators between the hydrophilic photosensitive components and the environment, reducing moisture interaction while preserving the photosensitivity required for high-performance recording.
3Manufacturing precision
If the resin matrix absorbs moisture during storage, then refractive index changes occur affecting optical quality, but storage stability is reduced
Solution Approach 1:
The patent employs a composite resin matrix formulation that inherently resists moisture absorption through the synergistic combination of polyester, polyurethane, and epoxy resins with hydrophobic additives. This composite structure maintains consistent refractive index during long-term storage, preserving optical quality and enhancing storage stability simultaneously.
Solution Approach 2:
The patent optimizes the chemical composition parameters of the resin matrix to achieve a moisture absorption rate of 1.5 wt% or less. This parameter control prevents refractive index changes during storage, maintaining optical quality while improving storage stability and archival life.
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 results in a medium with improved storage stability and compatibility, maintaining high sensitivity and optical quality over time by minimizing water incorporation and refractive index changes, thus enhancing shelf life and archival life of recorded information.
Implementation Method 1
the photosensitive compound moves by diffusion from a weakly irradiated portion to a strongly irradiated portion. As a result, owing to the concentration difference of the photosensitive compound in the recording layer, a refractive index difference develops
Implementation Method 2
A hologram recording material is irradiated with a direct coherent light which does not illuminate the object, in addition to a light from an object
Implementation Method 3
On the hologram recording material, interference stripes between the reference light and the object light is recorded as image information
Implementation Method 4
when the recording material treated as above is irradiated with the same light (reproduction illumination light) as the reference light, the light is diffracted by holograms in a manner that the wave surface of the reflected light, which has originally arrived at the recording material from the object in the recording step, is reproduced
Data Source
Figure 1
AI summary
Disclosed is a volume hologram optical recording medium having a recording layer with low moisture absorption. Specifically disclosed is a volume hologram optical recording medium having a multi-layer structure including a transparent substrate and a recording layer. The recording layer contains a resin matrix (A) and/or a resin matrix (B) and a photosensitive compound (C). The resin matrix (A) is obtained by reacting a polyisocyanate (A1) and a polyol (A2) having a -(C=O)O- group and/or a -O(C=O)O- group, while the resin matrix (B) is obtained by reacting an epoxy compound (B1) having two or more epoxy groups in one molecule and a curing agent (B2). In addition, the recording layer has a moisture absorption rate of 1.5 wt% or less.