Spectrometer Assembly Using Continuous Dielectric Metal Filter
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Solution Overview
Problem
The miniaturization of spectrometers is hindered by the need for bulky collimating optical elements to ensure sufficient wavelength selectivity, which increases the size of the assembly, particularly in applications like subcutaneous glucose monitoring systems.
Innovation Solution
A spectrometer assembly using optical filters with a stack of continuous, non-micro-structured alternating dielectric and metal layers, reducing angular sensitivity of the transmission wavelength and allowing for compact designs without the need for collimating elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If collimating optical elements (lenses or mirrors) are used to ensure wavelength selectivity, then the spectrometer achieves sufficient wavelength resolution, but the device size increases significantly
Solution Approach 1:
The patent changes the optical parameters of the filter by using a stack of alternating dielectric and metal layers with specific thicknesses and refractive indices. This layered structure modifies the filter's angular sensitivity characteristics, allowing it to maintain wavelength selectivity without requiring collimated light, thus eliminating the need for bulky lenses or mirrors
Solution Approach 2:
The patent employs a composite optical filter consisting of alternating layers of dielectric materials and metal layers. This composite structure combines the advantages of both material types to achieve low angular sensitivity while maintaining high wavelength selectivity, enabling compact spectrometer design without collimating elements
2Loss of energy
If metal layers are micro-structured to reduce insertion loss, then optical transmission improves, but angular sensitivity of transmission wavelength increases
Solution Approach 1:
The patent changes the structural parameter of the metal layers from micro-structured to continuous, and adjusts the thickness parameters of both metal and dielectric layers. This parameter optimization achieves a balance between reducing insertion loss and minimizing angular sensitivity, allowing the filter to perform well in compact, non-collimated optical paths
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
This approach enables compact spectrometer assemblies with preserved wavelength selectivity, reducing size and improving light collection efficiency while maintaining corrosion resistance and low insertion loss.
Implementation Method 1
DE 44 42 045 A1 discloses optical interference filters comprising segments of alternating layers of dielectric materials and segments of alternating layers of metal and dielectric materials
Implementation Method 2
a photodetector 16 for providing an electrical signal upon illumination with the signal light
Data Source
Figure 1~2B
Figure 3~4B
Figure 4C~5
AI summary
A spectrometer assembly is provided having an optical transmission filter including a stack of continuous, non-patterned alternating dielectric (28) and metal (27) layers. Angle-dependent transmission wavelength shift of the optical transmission filter with continuous metal layers is small e.g. in comparison with multilayer dielectric filters, facilitating size reduction of the spectrometer assembly.