Seven-Layer Anti-Reflection Coating for Camera Lenses
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Solution Overview
Problem
Existing anti-reflection coatings for glass substrates in single-lens reflex cameras suffer from high reflection loss, leading to flare and ghost effects in photographs, and fail to adequately prevent tarnish, particularly in lenses with low to medium refractive indices.
Innovation Solution
A seven-layer anti-reflection coating structure comprising an alumina-based first layer, followed by layers of specific refractive indices and thicknesses, culminating in a porous silica aerogel layer with a fluororesin layer for water repellency, formed using vacuum vapor deposition and sol-gel methods, to achieve low reflectance and tarnish prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional multi-layer anti-reflection coating is formed on each lens, then reflectance is reduced to about 0.5%, but transmittance becomes 0.818 with reflection loss of about 18% due to cumulative effect on 20 lenses
Solution Approach 1:
The patent changes the refractive index parameters of the coating layers, specifically using a first layer with refractive index 1.70-2.00 and a second layer with refractive index 2.05-2.30, optimized for substrates with refractive index 1.45-1.72. This parameter optimization reduces reflectance to 0.3% or less at 550nm wavelength, and when applied to 20 lenses, achieves transmittance of 96% or more with reflection loss of 4% or less, eliminating flare and ghost effects
Solution Approach 2:
The patent employs a composite multi-layer structure combining different dielectric materials with specific refractive indices. The coating consists of at least two layers: a first layer (refractive index 1.70-2.00) and a second layer (refractive index 2.05-2.30), forming a composite system that optimizes optical performance. This composite structure achieves superior anti-reflection performance compared to conventional single-material coatings
2Reliability
If an anti-reflection coating is formed on a glass lens, then optical performance is improved, but tarnish (blue tarnish and white tarnish) occurs on the lens surface during production process
Solution Approach 1:
The patent applies the anti-reflection coating before the lens undergoes processes that cause tarnish. By forming the coating in advance on the glass lens surface, it creates a protective barrier that prevents basic components from dissolving into dew or water during grinding, and prevents chemical reactions that cause white tarnish. This preliminary coating application ensures both optical performance and tarnish prevention
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 provides excellent anti-reflection performance and tarnish prevention, reducing flare and ghost effects in single-lens reflex camera lenses, while maintaining optical clarity and durability.
Implementation Method 1
Each lens has a laminated anti-reflection coating comprising pluralities of dielectric layers each having a different refractive index from that of a lens substrate and a thickness of 1/2λ or 1/4λ, wherein λ is a center wavelength, to utilize interference effects.
Implementation Method 2
formed using vacuum vapor deposition and sol-gel methods
Implementation Method 3
formed using vacuum vapor deposition and sol-gel methods
Data Source
AI summary
An anti-reflection coating comprising first to seventh layers formed on a substrate in this order, the first layer being an alumina-based layer, the seventh layer being a porous, silica-based layer, and each of the first to seventh layers having predetermined refractive index and optical thickness in a wavelength range of 400-700 nm.