Diffractive Optical Element Thermal Stress Dispersion
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Solution Overview
Problem
Conventional diffractive optical elements fail to effectively reduce flare light generation when exposed to high-temperature environments for extended periods, leading to peeling issues between resin layers due to mismatched thermal expansion coefficients.
Innovation Solution
A diffractive optical element design featuring a first resin layer with a diffraction grating shape, a high refractive-index portion on the wall surfaces, and a close contact portion on the slopes, where the close contact portion's thickness is smaller than the wall surfaces' height, dispersing compressive stress and preventing peeling through the anchor effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a high refractive-index member is provided on wall surfaces to reduce flare light generation, then flare light is reduced, but peeling occurs between resin layers after high-temperature exposure due to thermal expansion mismatch
Solution Approach 1:
The invention divides the coating structure into three distinct segments: a first resin layer forming the diffraction grating, a high refractive-index member on the wall surfaces, and a second resin layer filling the gaps. This segmentation allows each layer to serve its specific function while distributing thermal stress, preventing peeling between layers after high-temperature exposure.
Solution Approach 2:
The invention applies different materials with specific properties to different locations: the high refractive-index member is selectively placed on wall surfaces where flare light originates, while the second resin layer is applied in the gap regions. This local differentiation optimizes both flare reduction and thermal stability without compromising overall structure.
2Reliability
If the close contact portion thickness is made smaller than wall surface height, then compressive stress is dispersed and peeling is prevented, but manufacturing precision requirements increase
Solution Approach 1:
The second resin layer is applied to partially cover the slopes rather than fully coating all surfaces. This partial action approach provides sufficient stress dispersion functionality while reducing the precision requirements compared to a complete coating, as the resin only needs to fill gaps and contact portions where stress concentration occurs.
Solution Approach 2:
The invention specifies that the close contact portion thickness be controlled within a particular range (smaller than wall surface height but larger than a minimum threshold). This parameter optimization balances stress dispersion effectiveness with manufacturing feasibility, ensuring reliable peeling prevention without excessive precision demands.
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 design significantly reduces flare light generation and prevents peeling between resin layers, maintaining optical efficiency even after prolonged exposure to high temperatures.
Implementation Method 1
a high refractive-index portion formed on the plurality of wall surfaces of the first resin layer and having a higher refractive index than the first and the second resin layers
Implementation Method 2
a first resin layer formed on the substrate and having a diffraction grating shape including a plurality of wall surfaces and a plurality of slopes
Data Source
AI summary
A diffractive optical element includes a substrate, a first resin layer formed on the substrate and having a diffraction grating shape including a plurality of wall surfaces and a plurality of slopes, a second resin layer formed in close contact with the first resin layer, a high refractive-index portion formed on the plurality of wall surfaces of the first resin layer and having a higher refractive index than the first and the second resin layers, and a close contact portion discontinuous with the high refractive-index portion, wherein the close contact portion is formed on the plurality of slopes of the first resin layer, and wherein a thickness of the close contact portion is smaller than a height of the plurality of wall surfaces.