Optical Component Antireflection Coating Overlap Design

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Solution Overview

Problem

Optical components with fine textured antireflection coatings suffer from film floating or peeling due to weak adhesion, leading to ghosting issues when a light-shielding coating is applied on top, especially on smooth surfaces, as the coatings have poor environmental durability and are prone to degradation.

Innovation Solution

An optical component design featuring an antireflection coating with a fine textured structure on the optically effective area and a light-shielding coating on the non-effective area, where the coatings overlap with each other, with the antireflection coating thickness decreasing towards the edge, and the light-shielding coating film thickness maintained between 3 µm and 50 µm, ensuring a stable overlap width between 0.5 µm and 50 µm to prevent film peeling and ghosting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a light-shielding coating film is formed on a smooth surface area with an antireflection coating of fine textured structure, then the adhesion strength is insufficient and film floating or peeling occurs, but forming the coating on a rough surface improves adhesion strength

Engineering Contradiction:
Improveadhesion strengthVSAvoidenvironmental durability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent applies different surface treatments to different areas: the light-shielding coating is formed on a rough surface area (Ra: 1-50 μm) to ensure adhesion strength, while the antireflection coating of fine textured structure is formed on a smooth surface area to maintain optical performance. This local differentiation resolves the contradiction between adhesion strength and environmental durability.

Inventive Principle:
Principle #3Local quality

2Object-affected harmful factors

If the edge of the light-shielding coating film is made to cover part of the antireflection coating, then gap production is prevented, but the overlap area requires precise control to avoid ghosting

Engineering Contradiction:
Improveharmful raysVSAvoidoverlap width control
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent specifies precise parameter ranges for the overlap width (0.5-50 μm) to balance two requirements: sufficient overlap to prevent gap formation and harmful ray penetration, while limited overlap to avoid ghosting. This parameter control resolves the contradiction between preventing harmful factors and maintaining manufacturing precision.

Inventive Principle:
Principle #35Parameter changes

3Illumination intensity

If the antireflection coating thickness is made uniform, then optical performance is maintained, but the edge area requires thickness reduction to prevent ghosting when overlapped with light-shielding coating

Engineering Contradiction:
Improveoptical transmittanceVSAvoidghosting
Core Design Contradiction:
Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The patent implements local quality variation in the antireflection coating thickness: the central area maintains uniform thickness for optimal optical transmittance, while the edge area (overlap area) has reduced thickness to prevent ghosting when overlapped with the light-shielding coating. This resolves the contradiction between optical performance and harmful factor prevention.

Inventive Principle:
Principle #3Local quality

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 prevents ghosting and film peeling, enhancing the environmental durability of the optical component by ensuring a stable overlap and appropriate film thicknesses, maintaining optical performance and reducing harmful reflections.

Implementation Method 1

an optically effective area having an antireflection coating with a fine textured structure of less than a use wavelength arranged thereon

Methodology Applied
Scientific EffectFine textured structure:

Implementation Method 2

an optically non-effective area having a light-shielding coating film arranged thereon

Methodology Applied
Scientific EffectLight shielding: Absorption (EM radiation)

Data Source

PatentEP3232237B1Optical component and method of manufacturing the same
Publication Date: 2023.03.01 CANON KK
  • EP3232237B1 patent drawingFigure 1~2
  • EP3232237B1 patent drawingFigure 3~4
  • EP3232237B1 patent drawingFigure 5

AI summary

An optical component has a surface including an optically effective area having an antireflection coating arranged thereon and an adjoining optically non-effective area having a light-shielding coating film arranged thereon. An edge portion of the antireflection coating and an edge portion of the light-shielding coating film overlap with each other to form an overlap area having a width between 0.5 µm and 50 µm. The antireflection coating is formed so as to show a thickness decreasing toward an edge thereof in the overlap area.