Hyperspectral Optical Element with Variable Depth Cavities
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Solution Overview
Problem
Existing infrared focal plane arrays (FPAs) require bulky imaging systems to achieve hyperspectral imaging, limiting their efficiency and practicality for detecting infrared radiation across various wavelengths.
Innovation Solution
A hyperspectral optical element with a variable gap is introduced, featuring a notched layer and a faceplate layer with a reflective inner surface, creating resonant cavities for specific wavelengths, and integrated with a Fabry-Perot etalon and on-chip thin film filters for side band rejection, allowing for tunable and efficient detection of infrared signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional infrared FPAs are used for hyperspectral imaging, then spectral detection capability is achieved, but the system becomes bulky and complex
Solution Approach 1:
The patent integrates the Fabry-Perot etalon structure directly into the focal plane array by notching the detector substrate to create cavity spaces. This nesting approach embeds the spectral filtering function within the detector itself, eliminating the need for separate bulk optical components and achieving compact hyperspectral imaging capability.
Solution Approach 2:
The patent combines multiple functions into a single integrated structure: the detector substrate serves as both the detection element and the etalon cavity wall, while the notched regions provide both structural definition and optical cavity formation. This merging of detector and spectral filtering functions reduces overall system complexity.
2Measurement precision
If variable gap cavities are introduced for wavelength selection, then spectral resolution is improved, but manufacturing complexity increases
Solution Approach 1:
The patent divides the detector substrate into multiple notched regions with different depths, where each notched region corresponds to a specific wavelength band. This segmentation allows independent optimization of cavity depths for different spectral channels while using standard semiconductor fabrication techniques to manage manufacturing complexity.
Solution Approach 2:
The patent varies the depth parameter of the notched cavities to tune the resonant wavelengths of the Fabry-Perot etalon. By controlling the cavity depth parameter during fabrication, different wavelength selections are achieved without requiring complex adjustable mechanisms, thus managing manufacturing precision requirements.
3Measurement precision
If on-chip thin film filters are added for side band rejection, then spectral purity is enhanced, but device complexity increases
Solution Approach 1:
The patent integrates thin film filters directly onto the detector chip surface, merging the side band rejection function with the existing detector and etalon structure. This on-chip integration eliminates the need for separate external filter components and maintains a compact form factor while enhancing spectral purity.
Solution Approach 2:
The thin film filters are deposited as nested layers on the detector surface, with the filter functionality embedded within the chip structure itself. This nesting approach incorporates additional spectral filtering capability without adding external bulk to the system.
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 solution enables compact, efficient, and tunable hyperspectral imaging, allowing for the separation and detection of specific wavelengths, improving the resolution and spectral sampling capabilities of infrared sensors.
Implementation Method 1
The plurality of variable depth cavities provides resonant cavities for one or more wavelengths of the received signal
Implementation Method 2
A notched layer, such as a notched staircase or other configuration notched layer, includes a plurality of notched surfaces and is mounted to the faceplate layer. The notched surfaces oppose the reflective inner surface of the faceplate and define a plurality of variable depth cavities
Data Source
AI summary
A hyperspectral optical element for monolithic detectors is provided. In one embodiment, for example a hyperspectral optical element includes a faceplate layer adapted to be mounted on top of a monolithic detector. The faceplate layer comprises a reflective inner surface. A notched layer includes a plurality of notched surfaces and is mounted to the faceplate layer. The notched surfaces oppose the reflective inner surface of the faceplate and define a plurality of variable depth cavities between the reflective inner surface of the faceplate layer and the plurality of notched surfaces of the notched layer. The faceplate layer and the notched layer are substantially transparent to a received signal and the plurality of variable depth cavities provides resonant cavities for one or more wavelengths of the received signal.