Static 2D Aperture Coding for Diffuse Source Spectroscopy
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Solution Overview
Problem
Traditional spectrometers face challenges in maximizing throughput without sacrificing spectral resolution when dealing with diffuse sources, and in achieving high signal-to-noise ratio (SNR) due to the limitations of narrow slits and single-channel detectors.
Innovation Solution
A static multimode multiplex spectrometer (MMS) is developed, which replaces the slit with a two-dimensional orthogonal column code mask, combined with a dispersive element and a two-dimensional detector array, allowing for high throughput and high spatial resolution by converting intensity information into spectral information using orthogonal or independent column codes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a narrow input slit is used to achieve high spectral resolution, then spectral resolution is improved, but throughput is reduced
Solution Approach 1:
The input slit is segmented into multiple sub-slits arranged in a coded aperture pattern. This allows the system to maintain spectral resolution through the dispersive element while increasing throughput by allowing light from multiple spatial locations to enter the spectrometer simultaneously. The coded aperture pattern creates distinct spatial signatures for different spectral channels.
Solution Approach 2:
The patent transitions from a one-dimensional slit aperture to a two-dimensional coded aperture mask. This dimensional change allows the system to encode both spatial and spectral information simultaneously, enabling high throughput while maintaining spectral resolution through the added spatial coding dimension.
2Productivity
If the input aperture size is increased to maximize throughput, then throughput is improved, but spectral resolution is reduced
Solution Approach 1:
The large input aperture is segmented into multiple smaller sub-apertures arranged in a coded pattern. Each sub-aperture contributes to a specific spectral channel through the dispersive element, allowing the system to maintain spectral resolution while collecting light over a large total aperture area for high throughput.
Solution Approach 2:
The coded aperture mask acts as an intermediary between the large input aperture and the dispersive element. It encodes spatial information into the light field before it reaches the dispersive element, allowing the system to maintain spectral resolution even when using a large input aperture for high throughput.
3Device complexity
If a single-channel detector is used, then device complexity is reduced, but measurement precision is reduced
Solution Approach 1:
Multiple single-channel detectors are merged into a single two-dimensional detector array that captures both spatial and spectral information simultaneously. This allows the system to maintain relatively simple detector elements while achieving high measurement precision through the combined information from multiple spatial channels encoded by the coded aperture.
Solution Approach 2:
The two-dimensional detector array serves multiple functions: it detects both spatial and spectral information, and can be used to reconstruct spectra for multiple sources simultaneously. This multi-functionality allows the system to achieve high measurement precision without requiring complex spectral dispersion instruments.
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
The MMS achieves high throughput and SNR, enabling the estimation of mean spectral density in a single time step with improved photon collection efficiency and spectral resolution, outperforming traditional spectrometers on diffuse sources.
Implementation Method 1
a dispersive element aligned with the code mask, wherein source radiation transmitted through the mask is incident on the dispersive element such that the dispersive element induces a wavelength dependent spatial shift of the image of the mask
Implementation Method 2
a two-dimensional detector array aligned with the dispersive element, wherein source radiation from the dispersive element is incident on the array, wherein the array comprises row and column detector elements, and wherein the detector elements convert the wavelength dependent spatial shift image of the mask into a light intensity values
Data Source
AI summary
A class of aperture coded spectrometer is optimized for the spectral characterization of diffuse sources. The instrument achieves high throughput and high spatial resolution by replacing the slit of conventional dispersive spectrometers with a spatial filter or mask. A number of masks can be used including Harmonic masks, Legendre masks, and Hadamard masks.