Optical Visor Coating With Notch Filters for Secondary Reflection Control
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Solution Overview
Problem
Existing anti-reflective coatings on visors suffer from secondary reflections, which are optically inefficient and potentially dangerous, especially in visually critical contexts.
Innovation Solution
A coating comprising multiple notch filters at different predetermined wavelength regions, specifically designed for polycarbonate visors, to reduce secondary reflections by enhancing the reflectivity of narrow wavelength bands and maintaining optimal outside world transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard coating is applied to the visor to reduce scratching, then the visor's scratch resistance is improved, but the optical performance of anti-reflection coating is worsened due to optical interference
Solution Approach 1:
The coating system is segmented into multiple functional layers: a hard protective layer for scratch resistance, and a separate multi-layer dielectric anti-reflection coating with notch filters for optical performance. This segmentation allows each layer to independently fulfill its specific function without compromising the other.
Solution Approach 2:
The solution employs composite material structure with multiple dielectric layers having different optical properties. The combination of layers with specific refractive indices and thicknesses creates the desired anti-reflection effect with notch filters at specific wavelengths, while the hard coating provides mechanical protection.
2Strength
If a conventional anti-reflection coating is deposited on the hard coating, then the visor's scratch resistance is maintained, but secondary reflections are introduced which reduce optical efficiency
Solution Approach 1:
The patent changes the optical parameters of the anti-reflection coating by incorporating notch filters with specific reflectivity percentages (e.g., 80%, 70%, 65%) at different wavelength regions. This parameter optimization allows the coating to reflect harmful secondary reflections while maintaining high transmission for primary light paths.
Solution Approach 2:
The patent converts the harmful secondary reflections into a beneficial effect by using the same optical interference principles to create notch filters that selectively reflect unwanted wavelengths. The secondary reflections that would normally degrade performance are instead harnessed to filter out specific wavelength bands, improving overall optical quality.
3Loss of energy
If the anti-reflection coating performance is optimized to reduce secondary reflections, then optical efficiency is improved, but the complexity of the coating structure increases
Solution Approach 1:
The complex optical function is segmented into multiple simpler layers, each with a specific role: substrate layer, hard protective layer, and multi-layer dielectric anti-reflection coating with notch filters. This segmentation makes the overall system more manageable and manufacturable despite the sophisticated optical performance requirements.
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 coating significantly reduces secondary reflections, enhances primary image brightness, and maintains high transmissivity for real-world viewing, while improving contrast for augmented or virtual imagery.
Implementation Method 1
The coating comprises multiple notch filters located at different predetermined wavelength regions... enhancing the reflectivity of narrow wavelength bands
Implementation Method 2
maintains high transmissivity for real-world viewing
Data Source
AI summary
A coating for an optical surface for reducing secondary reflections from narrow wavelength band image sources, the coating comprising multiple notch filters located at different predetermined wavelength regions.