Thin Optical Filter Arrays With Molding Compound
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Solution Overview
Problem
Conventional optical filters in small form factor systems, such as handheld spectrometers, face challenges due to their thickness, which increases system size and weight, and degrades filtering quality by causing optical noise and signal overlap, while existing manufacturing processes produce filters with thick substrates that are difficult to handle and occupy excessive space.
Innovation Solution
The development of an array of optical filters with a molding compound disposed between first and second optical filters, where the filters are thinned using a back-grinding technique to achieve a thickness range of 50 μm to 500 μm, reducing overall thickness and improving handling and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If conventional optical filters are made thin to reduce system size and weight, then portability is improved, but manufacturing complexity and handling difficulty increase
Solution Approach 1:
The filter is divided into separate functional layers: a substrate layer and a filter layer. This segmentation allows the substrate to be manufactured separately and then combined with the filter layer, enabling thin filter designs while maintaining manufacturing feasibility through modular assembly processes
Solution Approach 2:
The filter layer is nested within or attached to the substrate, creating a composite structure where the thinner filter layer is supported by the substrate. This nesting approach reduces overall filter thickness and weight while simplifying handling during manufacturing
2Measurement precision
If filter substrate thickness is reduced to improve performance, then optical noise and signal overlap are reduced, but filter strength and handling capability deteriorate
Solution Approach 1:
The filter combines a substrate material with a filter layer material to create a composite structure. The substrate provides mechanical strength and handling capability, while the filter layer provides the required optical filtering properties. This composite approach enables thin filters that maintain both strength and optical performance
Solution Approach 2:
Different regions of the filter structure have different properties: the substrate provides mechanical support where strength is needed, while the filter layer provides optical functionality where transmission and filtering are critical. This local differentiation of material properties optimizes both mechanical and optical performance
3Area of stationary object
If multiple optical filters are placed close together to reduce array size, then device footprint is reduced, but optical interference and signal overlap increase
Solution Approach 1:
Each filter in the array is separated by spacing structures that prevent optical interference. This segmentation of the filter array into distinct, spaced-apart filter elements allows compact packaging while maintaining optical isolation between adjacent filters
Solution Approach 2:
Spacing structures or medium materials are introduced between adjacent filters to act as optical barriers. These intermediary elements prevent unwanted optical interference and signal overlap while allowing the filters to be positioned close together for compact array configuration
Data Source
AI summary
An array of optical filters having a front side and a back side is disclosed. The array of optical filters includes first and second optical filters and a molding compound. The first and second optical filters each include a substrate having a back surface coplanar with the back side of the molding compound, and a filter layer having a front surface coplanar with the front side of the molding compound. The molding compound covers the sidewalls of the filter substrates and filter layers, and fills gaps between the filters.