Diffractive Optical Element Resin Interface Adhesion
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Solution Overview
Problem
Diffractive optical elements with two resins of different optical characteristics face peeling issues at the interface due to differences in swelling and coefficients of linear expansion when exposed to high-temperature and high-humidity environments, leading to stress and separation of resin layers.
Innovation Solution
A diffractive optical element is designed with a first resin layer containing a thiol group and a second resin layer with a sulfide group, where the curing reaction is controlled to form sulfide bonds at the interface, ensuring α<β, which enhances adhesion and reduces peeling by maintaining a higher sulfide group content in the second region compared to the first region, as measured by laser Raman spectroscopy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two resins with different optical characteristics are used in a diffractive optical element, then diffraction efficiency is improved, but peeling occurs at the interface due to different swelling and coefficients of linear expansion in high-temperature and high-humidity environments
Solution Approach 1:
The patent changes the chemical composition parameters of the resin layers by introducing thiol groups in the first resin and sulfide groups in the second resin. This chemical modification enables the formation of sulfide bonds at the interface, which alters the physical and chemical properties to improve adhesion while maintaining the optical characteristics needed for diffraction efficiency.
Solution Approach 2:
The patent creates a composite resin structure where two different resins with specific functional groups (thiol and sulfide) are combined in a layered configuration. This composite approach allows each resin to contribute its optical properties while the interface chemistry (sulfide bonds) provides mechanical bonding, resolving the contradiction between optical performance and interface stability.
2Strength
If the curing reaction is controlled to form sulfide bonds at the interface, then adhesion is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent incorporates thiol groups in the first resin and sulfide groups in the second resin during the resin formulation stage, before the curing process. This preliminary preparation ensures that when the resins are joined, sulfide bonds can form automatically at the interface without requiring additional processing steps, thereby simplifying manufacturing while achieving strong adhesion.
Solution Approach 2:
The thiol and sulfide groups are designed to react with each other automatically at the interface when the resins are joined. This self-reacting mechanism eliminates the need for external catalysts or complex curing processes to form the bonds, making the manufacturing process simpler while ensuring strong interface adhesion.
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 effectively suppresses peeling at the interface between the resin layers, even in harsh environments, maintaining high adhesion and diffraction efficiency, as demonstrated by durability tests in high-temperature and high-humidity conditions without significant degradation.
Implementation Method 1
forming a first resin layer having a diffraction grating shape by disposing a thiol group-containing first resin composition on a first substrate, and forming a second resin layer having a diffraction grating shape by disposing a second resin composition on the first resin layer, in which in forming the second resin layer, the second resin composition is cured to satisfy α<β
Implementation Method 2
when measurement is performed by laser Raman spectroscopy, α[0005] where α is the ratio of the intensity of a peak corresponding to sulfide groups to the intensity of a peak corresponding to thiol groups in a second region R2, and β is the ratio of the intensity of a peak corresponding to sulfide groups to the intensity of a peak corresponding to thiol groups in a first region R1
Data Source
AI summary
Diffractive optical element includes two resin layers stacked on first substrate. One of the two resin layers is cured article of first resin containing thiol group and sulfide group, the cured article having diffraction grating shape. The other is cured article of second resin, the cured article having diffraction grating shape. When measurement is performed by laser Raman spectroscopy, α<β, where α is the ratio of the intensity of peak corresponding to the sulfide group to the intensity of peak corresponding to the thiol group in first region containing no interface between the cured articles of the first and second resins, and β is the ratio of the intensity of peak corresponding to the sulfide group to the intensity of peak corresponding to the thiol group in second region containing the interface.