Wavelength Tunable Interference Filter Stray Light Suppression
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Solution Overview
Problem
Wavelength tunable interference filters face a decrease in spectroscopic precision due to stray light generated by metal electrodes used as apertures, which reflect light and reduce the accuracy of light measurement.
Innovation Solution
The use of a first electrode with a light absorbing layer closer to the substrate and a metal layer further away, positioned around the reflection film, reduces stray light by absorbing light that would otherwise be reflected and causing interference. This electrode configuration defines the light incident range on the reflection film, preventing light from entering areas outside the intended path and minimizing gaps between the electrode and reflection film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a metal electrode is used as an aperture to define the light incident range, then the light incident range is well-defined and spectroscopic precision is improved, but the metal electrode reflects incident light to generate stray light that decreases spectroscopic precision
Solution Approach 1:
A light absorbing layer is introduced as an intermediary between the incident light and the metal electrode. This layer absorbs the light that would otherwise be reflected by the metal electrode, preventing stray light generation while maintaining the aperture function of the electrode structure
Solution Approach 2:
The metal electrode's inherent light reflecting property, which causes harmful stray light, is converted into a beneficial function by positioning the light absorbing layer to utilize the electrode's structural definition capability while preventing its harmful reflection. The electrode structure defines the aperture precisely, and the light absorbing layer converts the potential harmful reflection into absorbed light that does not create interference
2Measurement precision
If the light absorbing layer is positioned closer to the substrate than the metal layer, then stray light is effectively absorbed and spectroscopic precision is enhanced, but the structural complexity of the electrode increases
Solution Approach 1:
The light absorbing layer and metal electrode layer are merged into a single integrated electrode structure where the light absorbing layer serves dual purposes: it absorbs stray light and provides additional electrical conductivity. This integration reduces the need for separate components and simplifies the overall device structure despite the multi-layer composition
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 suppresses stray light, enhancing spectroscopic precision by ensuring that only intended light is measured, thereby improving the accuracy of light transmission and reducing reflections that could lead to decreased precision.
Implementation Method 1
light that passes through the substrate and enters the light absorbing layer of the first electrode is absorbed by the light absorbing layer
Implementation Method 2
The pair of reflection films disposed in the wavelength tunable interference filter face each other and cause incident light to undergo an interference process to transmit light of a given wavelength
Data Source
AI summary
A wavelength tunable interference filter includes a fixed substrate, a fixed reflection film that is provided on the fixed substrate, reflects part of incident light, and transmits at least part of the incident light, a movable reflection film that faces the fixed reflection film, reflects part of incident light, and transmits at least part of the incident light, and a fixed electrode that surrounds the fixed reflection film and has a light absorbing layer and a metal layer, and the light absorbing layer is disposed closer to the fixed substrate than the metal layer.