Reflective Lens Coating Structure for High IR Reflectivity
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Solution Overview
Problem
Conventional reflective coatings in optical elements suffer from defects such as cracks and insufficient reflectivity, particularly in visible and infrared regions, due to improper material arrangement and environmental factors.
Innovation Solution
An optical lens assembly with a reflective element featuring a multi-layer coating structure comprising silver, titanium, chromium oxides, and optionally silicon compounds and metal oxides, designed to achieve high reflectivity and protect against cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional reflective coating membrane is used, then the manufacturing process is simple, but the reflectivity is insufficient and cracks occur
Solution Approach 1:
The patent applies composite materials by creating a multi-layer coating structure consisting of a reflective layer (silver or aluminum), an intermediate layer (titanium oxide or silicon oxide), and a protective layer (silicon nitride or silicon oxide). This composite structure combines the high reflectivity of metallic layers with the oxidation resistance and mechanical strength of ceramic layers, achieving both high reflectivity (>97.5% in 800-1000nm range) and crack prevention.
Solution Approach 2:
The patent segments the single-layer reflective coating into multiple functional layers. Each layer serves a specific purpose: the reflective layer provides high reflectivity, the intermediate layer prevents oxidation and reduces stress, and the protective layer enhances mechanical strength and environmental resistance. This segmentation resolves the contradiction by distributing functions across multiple layers rather than relying on a single complex material.
2Reliability
If the reflective coating membrane is made with simple material arrangement, then the manufacturing is easier, but cracks and defects occur due to environmental factors
Solution Approach 1:
The patent applies beforehand cushioning by introducing an intermediate layer between the reflective layer and the protective layer, as well as between the reflective layer and the substrate. This intermediate layer (titanium oxide or silicon oxide) acts as a stress buffer that prevents crack propagation from the substrate to the reflective layer, and provides a transition in thermal expansion coefficients, thereby preventing cracks before they occur under environmental stress.
Solution Approach 2:
The multi-layer composite structure combines materials with different properties: metallic layers for reflectivity, metal oxides for stress management and oxidation resistance, and ceramic layers for mechanical protection. This composite approach enhances crack resistance while maintaining manufacturability through established thin-film deposition techniques.
3Reliability
If a single-layer reflective coating is used, then the manufacturing process is simple, but the reflectivity in visible and infrared regions is insufficient
Solution Approach 1:
The patent uses composite materials to achieve high reflectivity across both visible and infrared regions. The metallic reflective layer (silver or aluminum) provides the base reflectivity, while the intermediate and protective layers are selected for their optical transparency in these regions. The combination maintains high reflectivity (>97.5% in 800-1000nm) without significant absorption or interference from the additional layers.
Solution Approach 2:
The patent applies local quality by optimizing each layer's thickness and material composition for its specific function while considering the overall optical performance. The reflective layer thickness is optimized for maximum reflectivity, the intermediate layer thickness is controlled to minimize optical interference, and the protective layer is designed to be thin enough to maintain optical transparency while providing sufficient mechanical protection.
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 multi-layer coating structure provides excellent reflectivity in the visible and near-infrared ranges, preventing oxidation and cracks, enabling miniaturization and improved image stabilization.
Implementation Method 1
the reflective coating membrane includes at least three coating layers of different materials... the coating layer made of the first material mainly includes silver... When an average reflectance in a wavelength range of 800 nm - 1000 nm of the reflective coating membrane is R80100, the following condition is satisfied: 97.5% ≤ R80100
Data Source
Figure 1A~1B
Figure 2
Figure 3A
AI summary
According to the present disclosure, an optical lens assembly includes at least two optical lens elements and at least one reflective element. The reflective element is made of a plastic material, the reflective element includes a reflective coating membrane, and the reflective coating membrane is disposed on a surface of the reflective element. The reflective coating membrane includes at least three coating layers of different materials, the at least three coating layers are respectively made of a first material, a second material and a third material, the first material mainly includes silver, the second material mainly includes titanium, the third material mainly includes chromium oxides, and the coating layer made of the first material and the coating layer made of the second material are disposed between the coating layer made of the third material and the reflective element. The average reflectance of the reflective coating membrane in a wavelength range of 800 - 1000 nm is at least 97.5%.