Interference Filter Alloy Mirrors High-Temperature Resistance

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Solution Overview

Problem

Existing interference filters using silver or silver alloys suffer from performance drops due to poor high-temperature resistance and process resistance, leading to reduced reflectance and transmittance over time, especially when subjected to processing and aging.

Innovation Solution

The use of alloy films with specific compositions such as Ag-P-Cu, Ag-P-In-Cu, and Ag-In-Sn, each with a thickness of 30-80 nm, which provide superior high-temperature and process resistance, maintaining reflectance and transmittance characteristics across the visible light spectrum.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a pure silver film is used for the mirrors, then high reflectance is achieved, but high-temperature resistance and process resistance are poor

Engineering Contradiction:
ImprovereflectanceVSAvoidhigh-temperature resistance and process resistance
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent uses composite alloy films combining silver with other metals (Al, In, Ga, or Ge) to create a material that maintains high reflectance while improving high-temperature and process resistance. The specific compositions (Ag-Al-In-Ga-Ge series alloys) create a composite structure that leverages the beneficial properties of each element.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent systematically varies the compositional parameters of the alloy films, specifically controlling the content ratios of Ag, Al, In, Ga, and Ge elements. By adjusting these parameters within specific ranges, the film achieves optimal balance between reflectance and resistance to high-temperature and processing conditions.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If an Ag-C alloy film is used for the mirrors, then high-temperature resistance and process resistance are improved, but reflectance is lowered

Engineering Contradiction:
Improvehigh-temperature resistance and process resistanceVSAvoidreflectance
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The patent replaces the Ag-C composite approach with a Ag-Al-In-Ga-Ge composite alloy system. This new composite material achieves both high reflectance and improved resistance to high-temperature and processing conditions, overcoming the reflectance loss problem associated with carbon-containing alloys.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the alloying strategy by eliminating carbon and using specific metallic elements (Al, In, Ga, Ge) in controlled amounts. This parameter change in composition fundamentally alters the material properties to simultaneously maintain high reflectance and improve thermal and process resistance.

Inventive Principle:
Principle #35Parameter changes

3Illumination intensity

If the alloy film thickness is increased, then reflectance is improved, but transmittance is reduced

Engineering Contradiction:
ImprovereflectanceVSAvoidtransmittance
Core Design Contradiction:
Illumination intensityVSLoss of energy

Solution Approach 1:

The patent optimizes the film thickness parameter within a specific range (30-80 nm) to achieve the desired balance between reflectance and transmittance. This precise parameter control allows the thin alloy film to provide sufficient optical functionality while maintaining energy efficiency.

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

These alloy films effectively suppress the reflectance and transmittance drops caused by processing and aging, ensuring stable performance of the interference filters by maintaining high reflectance over a wide wavelength band and improving adhesion to substrates.

Implementation Method 1

light is reflected between the pair of mirrors and only light having a specific wavelength is allowed to pass therethrough, while light having other wavelengths is cancelled by interference

Methodology Applied
Scientific EffectInterference: Interference

Implementation Method 2

The incident light between the two (a pair of) reflecting films that has entered from the outside through one of the reflecting films is reflected between the reflecting films

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2410369B1Interference filter, optical module, and analyzing device
Publication Date: 2015.10.14 SEIKO EPSON CORP
  • EP2410369B1 patent drawingFigure 1
  • EP2410369B1 patent drawingFigure 2
  • EP2410369B1 patent drawingFigure 3

AI summary

An interference filter is provided in which a fixed mirror (56) and a movable mirror (57) of the interference filter are selected from an Ag-Au alloy film, an Ag-Cu alloy film, an Ag-Au-Cu alloy film, an Ag-Si-Cu alloy film, an Ag-P-Cu alloy film, an Ag-P-In-Cu alloy film, an Ag-Te-Cu alloy film, an Ag-Ga-Cu alloy film, and an Ag-In-Sn alloy film.