Lens AR Coating Adhesion via CVD Intermediate Layer
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Solution Overview
Problem
The existing technologies face challenges in achieving strong adhesion between the lens and anti-reflective (AR) coating layers, particularly with the Atomic Layer Deposition (ALD) method, which limits material deposition and deteriorates optical properties due to the use of intermediate layers made of different materials, leading to issues with aberration correction and flare phenomena in camera lenses.
Innovation Solution
A lens assembly with an anti-reflective coating layer comprising alternately stacked first and second coating layers of different refractive indices, where an intermediate layer made of the same material as the coating layers is deposited using Chemical Vapor Deposition (CVD) to improve adhesion and maintain optical properties, specifically using SiO2 for the first coating layer and Al2O3 for the second, with a thickness of 10 to 20 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an intermediate layer made of different material is deposited between the lens and the AR coating layer, then adhesion between the lens and AR coating layer is improved, but optical properties deteriorate due to complex refractive index structure
Solution Approach 1:
The patent applies homogeneity by forming the intermediate layer from the same material (SiO2) as the first coating layer of the AR coating. This eliminates the complex refractive index structure caused by multiple different materials, maintaining simple optical properties while still providing adhesion enhancement through the intermediate layer structure.
Solution Approach 2:
The patent uses an intermediate layer as a mediator between the lens and the AR coating layer. This intermediate layer, formed by CVD, serves as an adhesion promoter while being composed of the same material as the first coating layer, thus mediating the adhesion function without complicating the optical structure.
2Manufacturing precision
If ALD coating method is used to form uniform coating on complex shapes, then coating uniformity is improved, but material deposition capability is limited and adhesion is weakened
Solution Approach 1:
The patent merges two deposition methods: CVD is used to form the intermediate layer for strong adhesion, and ALD is used to form the AR coating layers for uniformity. By combining these methods and using the same material (SiO2) for both the intermediate layer and first coating layer, the patent achieves both good adhesion and coating uniformity.
Solution Approach 2:
The patent changes the deposition method parameter from exclusively ALD to a combination of CVD and ALD. CVD provides better adhesion properties for the intermediate layer, while ALD ensures uniform coating for the AR layers. This parameter change in the deposition process resolves the adhesion weakness of pure ALD.
3Strength
If PVD coating method is used to form AR, then adhesion between lens and AR is maintained, but coating uniformity on complex shapes with severe curvature deteriorates
Solution Approach 1:
The CVD-formed intermediate layer acts as an intermediary that enables subsequent ALD coating to achieve uniform deposition on complex curved surfaces. The intermediate layer provides a suitable surface for ALD process, allowing the AR coating to be deposited uniformly even on lenses with severe curvature.
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
This solution enhances the adhesion between the lens and the AR coating layer, reduces reflectivity, and improves optical properties by simplifying the optical design and reducing the thickness of the coating layer, thereby minimizing aberrations and flare phenomena.
Implementation Method 1
The intermediate layer, disposed between the lens unit and the AR coating layer, is formed of a same material as the first coating layer or the second coating layer. The intermediate layer is disposed on the lens unit by chemical vapor deposition (CVD).
Implementation Method 2
a refractive index of the first coating layer is different from a refractive index of the second coating layer
Implementation Method 3
an anti-reflective (AR) coating layer, disposed on one surface of the lens unit, including a first coating layer and a second coating layer alternately stacked one or more times
Data Source
AI summary
A lens includes a lens unit; an anti-reflective (AR) coating layer, disposed on one surface of the lens unit, including a first coating layer and a second coating layer alternately stacked one or more times, wherein a refractive index of the first coating layer is different from a refractive index of the second coating layer; and an intermediate layer, disposed between the lens unit and the AR coating layer, is formed of a same material as the first coating layer or the second coating layer. The intermediate layer is disposed on the lens unit by chemical vapor deposition (CVD).