Multi-Layer Optical Interference Filter for Environmental Stability
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Solution Overview
Problem
Optical sensing devices face interference from undesired light waves, which degrade their ability to accurately detect information about objects, due to structural deficiencies in conventional interference filters that compromise reliability and robustness, especially when exposed to environmental conditions.
Innovation Solution
An optical sensing device with a multi-layer interference filter configuration using high and low refractive index materials like amorphous silicon and silicon dioxide, forming alternating layers that are resistant to delamination and physical deformation from environmental factors such as water and temperature, while attenuating undesired light waves based on their angle of incidence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional interference filters use certain layer materials to achieve light filtering, then the filter transmission characteristics can be tailored, but the filters exhibit structural deficiencies that compromise reliability and robustness when exposed to environmental conditions
Solution Approach 1:
The patent applies composite materials by combining multiple dielectric layers with different refractive indices (high refractive index materials like TiO2, Nb2O5, Ta2O5 and low refractive index materials like SiO2, Si3N4) to form an interference filter structure. This composite layering provides both the necessary optical filtering characteristics and improved structural stability against environmental conditions, resolving the contradiction between reliability and compositional stability.
Solution Approach 2:
The patent utilizes parameter changes by precisely controlling the thickness of each dielectric layer to optimize both optical performance and structural stability. By adjusting layer thickness parameters and refractive index parameters, the filter achieves tailored transmission characteristics while maintaining robustness against environmental factors such as temperature and humidity variations.
2Measurement precision
If interference filters use materials with high refractive index to reduce angle shift, then filter performance improves, but the filters become more susceptible to physical deformation from environmental conditions
Solution Approach 1:
The patent employs composite materials with alternating high and low refractive index layers. The high refractive index layers (TiO2, Nb2O5, Ta2O5) provide low angle shift and high optical performance, while the low refractive index layers (SiO2, Si3N4) provide structural support and resistance to physical deformation. This composite structure resolves the contradiction between measurement precision and strength.
Solution Approach 2:
The patent applies local quality by assigning different functional properties to different layers: high refractive index materials are placed where optical performance is critical for angle sensitivity, while low refractive index materials are positioned to provide mechanical strength and environmental resistance. Each layer performs its specialized function, resolving the local contradiction between angle sensitivity and physical robustness.
3Reliability
If interference filters are designed for specific filter properties to attenuate undesired light waves, then optical performance is optimized, but the filters become vulnerable to delamination and structural damage under environmental exposure
Solution Approach 1:
The patent uses composite dielectric materials with alternating refractive indices to create an interference filter that maintains optimized optical performance for attenuating undesired light waves while the combined material structure provides resistance to delamination and environmental damage. The composite structure synergistically combines optical functionality with environmental durability.
Solution Approach 2:
The patent implements beforehand cushioning by designing the multi-layer dielectric structure to preemptively resist environmental stresses such as humidity, temperature variations, and mechanical stress before damage can occur. The layered composite structure acts as a protective system that prevents delamination and structural damage before they can compromise the optical performance.
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 enhances the physical stability and reliability of optical interference filters, effectively reducing optical cross-talk and maintaining high transparency in the near-infrared spectrum, thereby improving the accuracy of object detection in various environmental conditions.
Implementation Method 1
Optical interference filters leverage filter transmission technology to attenuate or block the undesired light waves from reaching the photodetector
Implementation Method 2
the interference filter is designed to include layer materials that have a high refractive index, such as amorphous silicon or hydrogenated amorphous silicon
Data Source
AI summary
An optical device includes an emitter operable to emit a first light wave. The optical device also includes a detector operable to detect a second light wave that is based on the first light wave. The second light wave is susceptible to being coupled with an undesired light wave that is based on the first light wave. The optical device further includes an interference filter disposed on the detector. The interference filter includes a first filter portion and a second filter portion having a first set of layers formed from a first material and a second set of layers formed from a second, different material. The interference filter is operable to attenuate undesired light waves in multiple distinct environments based on the first and second sets of layers in the second filter portion.