Antireflection Film for Optical Elements
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Solution Overview
Problem
Existing antireflection films on optical elements, particularly in large-open angle lenses, suffer from film unevenness and insufficient antireflection performance due to the refractive index mismatch between the substrate and the film layers, leading to inadequate light reflection reduction across the entire lens surface.
Innovation Solution
A two-layer antireflection film comprising a first layer and a second layer, both made of organic compounds, with specific refractive index and thickness ranges that satisfy certain inequalities to ensure uniform film distribution and optimal antireflection performance, formed using a wet film forming method like spin coating to prevent unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vapor deposition is used to form the antireflection film, then the film can be formed on the substrate, but film unevenness occurs in the lens surface and antireflection performance is insufficient
Solution Approach 1:
The patent replaces the vapor deposition process (physical vapor deposition) with a solution coating process. The antireflection film is formed by coating a solution containing organic compound particles onto the lens surface and drying it, rather than using vapor deposition. This substitution eliminates the film unevenness problem while maintaining antireflection performance.
Solution Approach 2:
The patent changes the refractive index parameters of the film layers to resolve the contradiction. By selecting organic compounds with specific refractive indices (first layer: 1.30-1.70, second layer: 1.10-1.26) and controlling the optical thickness products (n1d1 and n2d2 between 100-155), the patent achieves both uniform film formation and sufficient antireflection performance across the entire lens surface.
2Reliability
If a material with low refractive index is used for the outermost layer, then antireflection performance improves, but refractive index mismatch with substrate causes insufficient performance
Solution Approach 1:
The patent divides the antireflection film into two distinct layers with different refractive indices. The first layer (closer to the substrate) has a higher refractive index (1.30-1.70) while the second layer (outermost) has a lower refractive index (1.10-1.26). This segmentation allows each layer to be optimized for its specific function, achieving both refractive index compatibility with the substrate and effective antireflection performance.
Solution Approach 2:
The patent uses a composite structure of two different organic compound materials with complementary refractive indices. The combination of these materials creates a multi-layer system that bridges the refractive index gap between the substrate (n=1.70-1.95) and air (n=1.0), achieving superior antireflection performance compared to a single-layer film.
3Ease of manufacture
If the refractive index of the top layer is about 1.27, then the film can be formed, but antireflection performance is insufficient when substrate refractive index is 1.70 or less
Solution Approach 1:
The patent expands the refractive index range for the first layer from the conventional single value (1.27) to a broader range (1.30-1.70). This parameter change allows the film to be formed on substrates with varying refractive indices (1.70-1.95) while maintaining optimal antireflection performance. The second layer maintains its refractive index range of 1.10-1.26, creating a flexible composite structure that adapts to different substrate properties.
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 provides improved antireflection performance across the entire lens surface with reduced reflectance, maintaining consistent reflectance characteristics between the center and periphery, effectively addressing the issues of film unevenness and refractive index mismatch.
Implementation Method 1
The first layer and the second layer each include an organic compound. The following inequalities are satisfied: 1.30≤n1≤1.70, 1.10≤n2≤1.26, where n1 is a refractive index of the first layer and n2 is a refractive index of the second layer.
Implementation Method 2
Dielectric multilayers (antireflection films) with an antireflection function are often formed on the surface of an optical element such as a lens and a filter in an optical system to prevent a flare and a ghost caused by unnecessary reflections of light.
Data Source
AI summary
An optical element includes a substrate, and an antireflection film. The antireflection film consists of a first layer formed on the substrate, and a second layer formed on the first layer. The first layer and the second layer each include an organic compound. Predetermined inequalities are satisfied.