Photopolymer Composition for High-Temperature Hologram Stability
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Solution Overview
Problem
Hologram recording media face challenges in maintaining stable optical recording characteristics over time due to photoinitiator reactions during storage, leading to issues like halo formation and decreased diffraction efficiency.
Innovation Solution
A photopolymer composition comprising a siloxane-based polymer with a silane functional group crosslinked with a (meth)acrylic-based polyol, combined with a photoinitiator system of a photosensitizing dye and an electron donor, enhances stability and refractive index modulation, allowing for clear image reproduction without halo.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photoinitiator system is used in the photopolymer composition, then photopolymerization and hologram recording are enabled, but the photoinitiator reacts during storage leading to decreased stability and optical recording characteristics
Solution Approach 1:
The patent extracts and separates the photoinitiator from the main photopolymer matrix, placing it in a distinct photopolymerizable layer that is formed separately. This physical separation prevents the photoinitiator from reacting during storage while still enabling it to function during the hologram recording process when the separate layer is irradiated.
Solution Approach 2:
The photopolymer composition is segmented into multiple functional layers: a photopolymerizable layer containing the photoinitiator and a separate polymer matrix layer. This segmentation allows each layer to perform its specific function independently, preventing unwanted reactions during storage while maintaining recording capability.
2Measurement precision
If the photopolymer layer thickness is decreased to improve angular selectivity, then angular selectivity increases, but the diffraction efficiency and refractive index modulation value are reduced
Solution Approach 1:
The patent introduces a vertical dimension by creating multiple layers with different functions at different depths. The photopolymerizable layer with photoinitiator is positioned separately from the polymer matrix, allowing the system to achieve both thin-layer angular selectivity and high diffraction efficiency through the coordinated action of multiple layers rather than relying on a single thick layer.
Solution Approach 2:
The invention uses a composite structure combining a photopolymerizable layer containing photoinitiator with a polymer matrix layer. This composite material system enables the photopolymer to achieve high refractive index modulation and diffraction efficiency while maintaining the angular selectivity benefits of thin layers, as the composite structure works synergistically to compensate for the thickness limitation.
3Ease of manufacture
If conventional photopolymer composition is used, then hologram recording is achieved, but halo formation occurs and diffraction grating collapse is observed
Solution Approach 1:
The patent introduces a photopolymerizable layer as an intermediary component between the light source and the polymer matrix. This intermediate layer containing photoinitiator mediates the photopolymerization process, controlling where and when polymerization occurs to prevent halo formation and diffraction grating collapse while maintaining recording capability.
Solution Approach 2:
The photopolymerizable layer is prepared in advance with the photoinitiator positioned to activate polymerization at specific locations during recording. This preliminary preparation ensures that polymerization occurs only where needed, preventing unwanted side reactions that cause halo formation and maintaining the integrity of diffraction gratings.
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 composition provides a hologram recording medium with excellent optical recording characteristics and stability at various temperatures, maintaining refractive index modulation and preventing diffraction grating collapse.
Implementation Method 1
a photopolymer composition for preparing a hologram includes a polymer matrix, a photoreactive monomer, and a photoinitiator system, and the photopolymer layer prepared from such a composition is irradiated with laser interference light to induce photopolymerization of local monomers
Implementation Method 2
a photoinitiator system containing a photosensitizing dye and a coinitiator, wherein the coinitiator includes an electron donor whose reaction energy with a photosensitizing dye excited into a triplet state is-25 to 0 KJ/mol
Data Source
AI summary
The present invention relates to a photopolymer composition, a hologram recording medium, a preparation method thereof, and an optical element comprising the same. The photopolymer composition includes an electron donor whose reaction energy with a photosensitizing dye excited into a triplet state is-25 to 0 KJ/mol, thereby being able to provide a hologram recording medium that not only is excellent in optical recording characteristics such as diffraction efficiency which are the basic physical properties of hologram recording media, but also exhibits excellent high-temperature stability over time before recording optical information, so that it can exhibit the originally intended optical recording characteristics even when stored at room temperature to high temperature for a long period of time, and can reproduce clear images without problems such as halo.