Multispectral Filter With Mixed Quarterwave Stacks for Fine Tuning
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Solution Overview
Problem
Existing multispectral filters face challenges in achieving precise control over bandwidth and transmissivity due to significant changes in optical characteristics when altering the thickness of the spacer or quantity of quarterwave stacks, limiting the ability to tune the filter response effectively.
Innovation Solution
Implementing a mixed quarterwave stack configuration with multiple materials and varying thicknesses of quarterwave stacks, along with unpaired layers, to achieve greater granularity in tuning the multispectral filter's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the thickness of the spacer or quantity of quarterwave stacks is altered, then the bandwidth and transmissivity of the filter can be adjusted, but the optical characteristics change significantly, limiting precise tuning control
Solution Approach 1:
The patent applies parameter changes by varying the thickness of individual quarterwave stack layers and the spacer layer to precisely control the filter's optical characteristics. By adjusting these dimensional parameters, the bandwidth and transmissivity can be tuned with fine granularity without causing significant unintended changes in other optical properties.
Solution Approach 2:
The patent uses composite material structures consisting of multiple alternating layers of dielectric materials with different refractive indices (high-index and low-index materials) to form the quarterwave stacks. This composite structure enables precise control over the spectral response by manipulating the optical interference effects within the layered composite system.
2Ease of manufacture
If a simple quarterwave stack structure is used, then the filter design is straightforward, but the ability to achieve precise bandwidth and transmissivity control is limited
Solution Approach 1:
The patent segments the quarterwave stack into multiple individual layers of alternating high-index and low-index materials. By dividing the stack into discrete layers with controllable thicknesses, the design achieves precise spectral control while maintaining a manufacturable layered structure that can be deposited using standard thin-film techniques.
Solution Approach 2:
The patent implements local quality by assigning different thickness values to specific layers within the quarterwave stack based on their position and optical function. This localized variation in layer thickness allows precise control over the filter's spectral characteristics at different wavelengths, enabling tailored bandwidth and transmissivity profiles.
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
Enables precise control over the spectral range, transmissivity, and bandwidth of the multispectral filter, allowing for more nuanced filtering capabilities.
Implementation Method 1
A multispectral filter may include a first mirror, a second mirror, and a spacer disposed between the first mirror and the second mirror. Each of the first mirror and the second mirror may include a set of quarterwave stacks
Implementation Method 2
Each of the first mirror and the second mirror may include a set of quarterwave stacks
Implementation Method 3
a spacer disposed between the first mirror and the second mirror
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An optical filter may include a substrate. The optical filter may include a first mirror and a second mirror. Each of the first mirror and the second mirror may include a plurality of quarterwave stacks. The plurality of quarterwave stacks may include a plurality of layers comprising a first material, a second material, and a third material. The optical filter may include a spacer disposed between the first mirror and the second mirror.