Optical Lens Assembly Coating for Thermal Mismatch and Layer Adhesion
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Solution Overview
Problem
Conventional anti-reflective membrane layers in optical modules suffer from significant thermal expansion differences with the substrate, leading to relative displacement and potential detachment, which affects image quality due to temperature changes.
Innovation Solution
An optical lens assembly with a glass lens element featuring a non-planar optical surface and an anti-reflective membrane layer comprising a nanostructure layer made of aluminum oxide and a structure connection film of silicon dioxide, where the silicon dioxide layer thickness is between 20 nm and 150 nm, ensuring a linear expansivity of 12×10−7/K to 210×10−7/K, reducing relative displacement and maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional anti-reflective membrane layer is used on the optical lens, then the reflectivity is reduced, but the layer detaches or destroys due to thermal expansion differences with the substrate
Solution Approach 1:
The patent applies composite materials by creating a multi-layer structure consisting of a silicon dioxide layer and an aluminum oxide nanostructure layer. The silicon dioxide layer has a linear expansivity of 5.5×10−7/K to 7.5×10−7/K, which is closer to the glass substrate's thermal expansion coefficient than conventional anti-reflective coatings. This composite structure reduces thermal stress and prevents detachment while maintaining anti-reflective properties through the aluminum oxide nanostructures.
Solution Approach 2:
The patent changes the physical parameters of the anti-reflective membrane by controlling the thickness of the silicon dioxide layer (20 nm to 150 nm) and the linear expansivity (5.5×10−7/K to 7.5×10−7/K). By adjusting these parameters, the membrane achieves both low reflectivity and thermal stability, resolving the contradiction between optical performance and structural reliability under temperature variations.
2Object-affected harmful factors
If the anti-reflective membrane layer is made thinner to reduce reflection, then the optical quality improves, but the layer becomes more susceptible to detachment
Solution Approach 1:
The patent uses a composite material system where the silicon dioxide layer provides mechanical strength and adhesion to the glass substrate, while the aluminum oxide nanostructure layer provides the anti-reflective function. This division of functional roles allows the anti-reflective layer to be thin (maintaining optical quality) while the silicon dioxide base layer ensures structural integrity and prevents detachment.
3Reliability
If the linear expansivity of the anti-reflective membrane is reduced to match the substrate, then thermal stability improves, but the manufacturing complexity increases
Solution Approach 1:
The patent achieves thermal stability by precisely controlling the linear expansivity parameter of the silicon dioxide layer (5.5×10−7/K to 7.5×10−7/K), which is closer to the glass substrate's expansion coefficient. This parameter optimization reduces thermal stress without requiring complex multi-layer structures, as the silicon dioxide itself provides both the thermal match and the mechanical bonding function.
Solution Approach 2:
The silicon dioxide layer acts as an intermediary between the glass substrate and the aluminum oxide anti-reflective nanostructures. It mediates the thermal expansion mismatch by having a linear expansivity intermediate between typical substrates and conventional anti-reflective coatings, thereby reducing stress while maintaining a relatively simple two-layer structure.
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 reduces layer detachment and maintains imaging quality by minimizing thermal expansion-related issues, ensuring low reflectivity and stability of the anti-reflective membrane layer across varying temperatures.
Implementation Method 1
the difference of thermal expansivity between the conventional anti-reflective membrane layer and the substrate is large, so a relative displacement occurs at the interface between the conventional anti-reflective membrane layer and the substrate due to temperature changing
Implementation Method 2
an anti-reflective membrane layer is formed on the optical surface, and the anti-reflective membrane layer includes a nanostructure layer and a structure connection film. The nanostructure layer has a plurality of ridge-like protrusions extending non-directionally from the optical surface
Data Source
AI summary
An optical lens assembly includes a glass lens element. The glass lens element has a refractive power, an optical surface of the glass lens element is non-planar, an anti-reflective membrane layer is formed on the optical surface, and the anti-reflective membrane layer includes a nanostructure layer and a structure connection film. The nanostructure layer has a plurality of ridge-like protrusions extending non-directionally from the optical surface, and a material of the nanostructure layer includes aluminum oxide. The structure connection film is disposed between the optical surface and the nanostructure layer, the structure connection film includes at least one silicon dioxide layer, the at least one silicon dioxide layer contacts a bottom of the nanostructure layer physically, and a thickness of the at least one silicon dioxide layer is greater than or equal to 20 nm and less than or equal to 150 nm.