Dual Pass Band Filter Element for Compact Optical Systems
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Solution Overview
Problem
Conventional optical filters can only allow a single specific band of light to pass through, necessitating multiple filter elements for devices operating in different bands, leading to increased device volume.
Innovation Solution
A dual-passband filter element with a bandpass filtering structure composed of alternately stacked first and second material layers with higher refractive indices, and an anti-reflection structure on the opposing surface, allowing two non-overlapping pass bands of light to pass through within the 400 nm to 1800 nm range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional single-band filter elements are used for each operating band, then each filter can only allow a specific band of light to pass through, but the device volume increases when multiple filters are configured for different bands
Solution Approach 1:
The patent combines multiple bandpass filtering functions into a single filter element by stacking alternating layers of first and second materials with different refractive indices. This multi-layer structure creates a dual pass band filter that allows two distinct bands of light to pass through simultaneously, eliminating the need for multiple separate filter elements and thereby reducing device volume.
Solution Approach 2:
The filter element achieves multi-functionality by designing a bandpass filtering structure that can operate across multiple wavelength bands. The alternating layer structure with specific refractive index differences enables the single filter to perform multiple filtering functions, allowing it to serve as a universal filter for different operating bands rather than requiring dedicated filters for each band.
2Adaptability or versatility
If multiple filter elements are configured to operate in different bands, then the device can meet diverse operating requirements, but the structural complexity and number of components increase
Solution Approach 1:
The patent merges multiple filtering functions into a single integrated filter element. By stacking alternating layers of materials with different refractive indices, the structure achieves dual pass band filtering capability, reducing the component count from multiple separate filters to one unified filter element, thereby simplifying the overall device structure.
Solution Approach 2:
The filter employs a composite structure consisting of alternating layers of first and second materials with different refractive indices. This composite material approach enables the single filter element to achieve complex multi-band filtering characteristics that would otherwise require multiple separate filters, reducing structural complexity while maintaining multi-band operation capability.
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 two distinct bands of light to pass through, expanding the application field of the filter element and reducing device volume by eliminating the need for multiple filter configurations.
Implementation Method 1
a bandpass filtering structure formed on the first surface and including a plurality of first material layers and a plurality of second material layers with a refractive index higher than the respective first material layers, wherein the first and second material layers are stacked alternately along a normal of the substrate
Implementation Method 2
a plurality of first material layers and a plurality of second material layers with a refractive index higher than the respective first material layers
Implementation Method 3
an anti-reflection structure formed on the second surface
Data Source
AI summary
A dual pass band filter element includes: a substrate, and a bandpass filtering structure and an anti-reflection structure formed on two opposite surfaces of the substrate. The bandpass filtering structure includes a plurality of first material layers and a plurality of second material layers with a refractive index higher than the respective first material layers, wherein the first and second material layers are stacked alternately along the normal of the substrate; the dual pass band filter element has a first pass band and a second pass band that does not overlap with the first pass band in a band of 400 nm to 1800 nm. In this way, two different bands of light are allowed to pass through the dual pass band filter element, thereby expanding the application field of the dual pass band filter element.