Far-Infrared Transmission Coating With MgO for Low-Reflection Films

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Solution Overview

Problem

Existing far-infrared ray transmission members face challenges in effectively suppressing reflection and require thicker films for adequate antireflection performance, and materials like MgF2 exhibit poor adhesion and limited process flexibility.

Innovation Solution

A far-infrared ray transmission member comprising a base material with a functional film containing MgO as a principal component in a low refractive index layer, with a refractive index ≤1.5 and a content of 50-100% MgO, to suppress reflection and facilitate flexible film formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If fluoride such as MgF2 is used as a low refractive index layer, then the refractive index is reduced to improve antireflection performance, but adhesion to base material or inorganic film deteriorates

Engineering Contradiction:
Improveantireflection performanceVSAvoidadhesion
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent changes the material parameter from fluoride (MgF2) to oxide (MgO), maintaining the low refractive index property while fundamentally improving adhesion characteristics. This material substitution resolves the contradiction by finding an alternative substance that satisfies both optical and adhesive requirements.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures, specifically forming an antireflection film comprising multiple layers including the oxide-based low refractive index layer. This layered composite approach allows optimization of each layer's properties, achieving both low reflection and good adhesion through the synergistic combination of materials.

Inventive Principle:
Principle #40Composite materials

2Illumination intensity

If conventional layered films are used for antireflection, then some reflection suppression is achieved, but film thickness must be increased to obtain appropriate antireflection performance

Engineering Contradiction:
Improveantireflection performanceVSAvoidfilm thickness
Core Design Contradiction:
Illumination intensityVSLength of stationary object

Solution Approach 1:

The patent changes the refractive index parameter of the low refractive index layer to be equal to or smaller than 1.5, which is a more stringent requirement than conventional designs. This parameter optimization, combined with the oxide material selection, enables achieving superior antireflection performance with reduced film thickness compared to conventional layered film structures.

Inventive Principle:
Principle #35Parameter changes

3Illumination intensity

If fluoride-based materials are used, then low refractive index is achieved, but the number of options of forming process on base material is limited

Engineering Contradiction:
Improverefractive indexVSAvoidforming process flexibility
Core Design Contradiction:
Illumination intensityVSAdaptability or versatility

Solution Approach 1:

The patent changes the material class from fluoride to oxide, which fundamentally expands the available forming process options. Oxide materials like MgO can be deposited using various techniques including sputtering, chemical vapor deposition, and atomic layer deposition, providing greater process flexibility and adaptability to different base materials compared to fluoride-based approaches.

Inventive Principle:
Principle #35Parameter changes

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 reflection and allows for the formation of an antireflection film with improved adhesion and process flexibility.

Implementation Method 1

a low refractive index layer containing oxide as a principal component and having a refractive index equal to or smaller than 1.5 with respect to light at a wavelength of 10 μm

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP4209762B1Far-infrared ray transmission member and method for manufacturing far-infrared ray transmission member
Publication Date: 2026.02.25 AGC INC
  • EP4209762B1 patent drawingFigure 1~2
  • EP4209762B1 patent drawingFigure 3
  • EP4209762B1 patent drawingFigure 4

AI summary

To appropriately suppress reflection of far-infrared rays, and appropriately form an antireflection film. A far-infrared ray transmission member (20) includes a base material (30) that transmits far-infrared rays, and a functional film (32) that is formed on the base material (30) and includes a low refractive index layer (34) containing oxide as a principal component and having a refractive index equal to or smaller than 1.5 with respect to light at a wavelength of 10 um. The low refractive index layer (34) contains MgO as a principal component, and a content of MgO is equal to or larger than 50 mass% and equal to or smaller than 100 mass% with respect to the entire low refractive index layer (34).