Compact mapping spectrometer
Inventors
Zollars, Byron G. • Mann, Chris W. • Elpers, Gabriel
Assignees
Publication Number
US-10254164-B2
Publication Date
2019-04-09
Expiration Date
2036-04-14
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Abstract
A compact, mapping spectrometer and various embodiments of the spectrometer are described. Methods for performing high-resolution spectroscopic, spatial, and polarimetric analyses of electromagnetic radiation across the complete electromagnetic spectrum, using spectrometer embodiments of the invention, are also described. The spectrometer and associated methods are useful for producing spectral and hyperspectral images associated with the incoming radiation and for identifying other information about electromagnetic radiation of interest.
Core Innovation
The invention provides a compact mapping spectrometer capable of high-resolution spectroscopic, spatial, and polarimetric analyses and imaging of electromagnetic radiation across broad regions of the electromagnetic spectrum. This spectrometer utilizes disordered media, specifically scatterers, and detector arrays to separate and identify spectral and polarization components of electromagnetic radiation incident on a radiation scatter layer. The invention enables the production of spectral and hyperspectral images of incoming radiation and facilitates identification of additional information, such as the polarization state, of the electromagnetic radiation.
The problem addressed by this invention arises from the limitations of current hyperspectral imaging systems, which typically require numerous optical components, complex instrumentation, precision alignment, and are often large, expensive, and rely on spatial scanning methods to assemble hyperspectral images. Commercially available snapshot hyperspectral detectors are not chip-scale and require bulky and expensive hardware for meaningful spectral identification. Alternative chip-scale systems remain complex, have limited spectral resolution, low radiometric efficiency, spatial-spectral artifacts, and/or acceptance angle issues.
The core innovation described in the patent is a spectrometer architecture comprising an array of apertures for passage of electromagnetic radiation, a scatter layer containing disordered media positioned to receive radiation from the apertures and to separate and scatter spectral and polarization components, and a detector array that captures these components as speckle patterns. After calibration, the distinctive speckle patterns allow computational reconstruction of the spectrum and polarization of the incoming radiation. Embodiments support chip-scale form factors, high radiometric efficiency, absence of moving parts, wide angular acceptance, and spatial registration of spectral components.
The spectrometer is compatible with additional features such as concentrator arrays to enhance throughput, scene element isolators for improved pixel mapping, and imaging optics for various application needs. Methods for analyzing electromagnetic radiation include capturing and computationally identifying spectral components based on detector array speckle patterns, producing hyperspectral images, and identifying materials or objects by comparing measured spectra with known references.
Claims Coverage
There are three independent claims in this patent, each covering distinct inventive features relating to the mapping spectrometer's structure and methods of use.
Spectrometer structure using aperture array, scatter layer with disordered media, and detector array
A mapping spectrometer comprising: - An array including a plurality of apertures configured to allow for passage of electromagnetic radiation through the apertures. - A detector array. - A scatter layer containing disordered media, positioned to receive electromagnetic radiation passing through the aperture array. - The disordered media are selected for scattering spectral components of the received electromagnetic radiation and for directing at least one spectral component to the detector array for detection.
Camera comprising the mapping spectrometer
A camera that comprises the mapping spectrometer with the following features: - The spectrometer includes an aperture array, a scatter layer with disordered media, and a detector array as previously described. - The camera integrates the described mapping spectrometer as a component.
Method for analyzing spectral components of electromagnetic radiation using the mapping spectrometer
A method comprising steps of: 1. Receiving electromagnetic radiation through the array of apertures to the scatter layer, then through the scatter layer and to the detector array. 2. Acquiring data from a speckle pattern produced on the detector array by at least one scattered spectral component of the received radiation. 3. Computationally identifying the at least one scattered spectral component of the electromagnetic radiation, based on the acquired speckle pattern data.
These inventive features establish the patent coverage for a compact, high-resolution mapping spectrometer apparatus using disordered media for spectral separation, its inclusion in camera systems, and methods for spectral analysis based on speckle pattern data.
Stated Advantages
High radiometric efficiency is achieved due to the spectrometer's design, including optional use of concentrators to direct radiation efficiently to the apertures.
The spectrometer provides high spectral resolution, enhanced by the scattering characteristics of the disordered media and calibration-based computational reconstruction.
The device features large angular acceptance of incident radiation, enabling versatility in various imaging configurations and input conditions.
Spatial registration of spectral components is ensured, allowing accurate mapping of spectra to specific spatial locations or scene elements.
The design enables the production of hyperspectral images without moving parts or spatial scanning, thereby simplifying hardware, reducing complexity, and increasing data acquisition speed.
Packaging can be chip-scale and compact, supporting integration into small devices or arrayed configurations.
The system can operate across any spectral band, from soft X-rays to microwave, depending only on the selection of detector arrays and scatter layer properties.
The spectrometer allows simultaneous, single-exposure acquisition of entire hyperspectral data sets, eliminating the need for mechanical scanning or assembly of image swaths.
Documented Applications
Satellite imaging for identification of remote objects.
Tracking and detecting chemical and physical markers in a variety of settings.
Manufacturing quality control systems, such as verification that spectral markers in a product or component meet specific parameters.
Medical imaging applications.
Detection and identification of mineral, biological, chemical species, or man-made objects using spectral data.
Analysis of hyperspectral images for situational awareness, such as identification of camouflage or disparity mapping in stereo vision.
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