|Publication number||US20060072109 A1|
|Application number||US 11/220,016|
|Publication date||Apr 6, 2006|
|Filing date||Sep 6, 2005|
|Priority date||Sep 3, 2004|
|Also published as||US8233148, US20080088840|
|Publication number||11220016, 220016, US 2006/0072109 A1, US 2006/072109 A1, US 20060072109 A1, US 20060072109A1, US 2006072109 A1, US 2006072109A1, US-A1-20060072109, US-A1-2006072109, US2006/0072109A1, US2006/072109A1, US20060072109 A1, US20060072109A1, US2006072109 A1, US2006072109A1|
|Inventors||Andrew Bodkin, Andrew Sheinis, Adam Norton|
|Original Assignee||Andrew Bodkin, Sheinis Andrew I, Adam Norton|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (3), Referenced by (18), Classifications (47), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application claims priority to U.S. provisional application Ser. No. 60/607,327, filed Sep. 3, 2004 and incorporated herein by reference.
The U.S. Government has certain rights in this invention as provided for by the terms of Grant #F19628-03-C-0079 awarded by the U.S. Air Force.
Hyperspectral imaging is a technique used for surveillance and reconnaissance in military, geophysical and marine science applications. Objects viewed by a hyperspectral imaging system are often displayed in three-dimensions, x, y (spatial) and λ (color wavelength). Spatial observations (x, y) allow a person to observe an image when high contrast is available. However, during conditions of low contrast, such as fog, smoke, camouflage, and/or darkness, or when an object is too far away to resolve, spectral signatures help identify otherwise unobservable objects, for example to differentiate between friendly and enemy artillery.
The hyperspectral imaging technique typically employs a scanning slit spectrometer, although Fourier-transform imaging spectrometers (FTIS), and scanning filter (Fabry-Perot) imaging systems have also been used. These devices, however, record only two-dimensions of a three-dimensional data set at any one time. For example, the scanning slit spectrometer takes spectral information over a one-dimensional field of view (FOV) by imaging a scene onto a slit then passing that collimated image from the slit through a dispersive element (prism) and re-imaging various wavelength images of the slit onto a detector array. In order to develop three-dimensional information, the slit is scanned over the entire scene producing different images that must be positionally matched in post-processing. The FTIS and Fabry-Perot techniques also scan; the former scans in phase space, and the latter scans in frequency
Current scanning spectrometer designs have resulted in large, expensive and unwieldy devices that are unsuitable for hand-held or vehicle applications. While these spectrometers have been employed effectively in airborne and satellite applications, they have inherent design limitations. These limitations arise due to motion of the associated platform, motion or changes in the atmosphere, and/or motion of the objects in the image field that occur during scan sequences. Motion of the platform results in mismatched and misaligned sub-images, reducing the resolution and hence the effectiveness of the observations, while a moving object, such as a missile, may escape detection if the object is moving faster than the spectrometer scan rate.
In one embodiment, a hyperspectral imaging system includes a focal plane array and a grating-free spectrometer that divides a field of view into multiple channels and that reimages the multiple channels as multiple spectral signatures onto the detector array.
In one embodiment, a hyperspectral imaging system includes a lenslet array that divides a field of view into multiple channels, optics that collimate electromagnetic energy of the multiple channels from the lenslet array, a grating that disperses the multiple channels into multiple spectral signatures and that reflects the electromagnetic energy back through the optics, and a focal plane array that detects the multiple spectral signatures.
In one embodiment, a hyperspectral imaging system includes imaging optics that form an image of an object, a focal plane array, a lenslet array that forms multiple images of a pupil of the imaging optics, and a prism and grating coupled to the lenslet array, to disperse the multiple images as multiple spectral signatures onto the focal plane array while blocking, by total internal reflection within the prism, unwanted spectral orders.
In one embodiment, a hyperspectral imaging system is provided. Imaging optics form an image of an object. An image slicer partitions a field of view of the imaging optics. For each partitioned part of the field of view, a focal plane array and a spectrometer divide a portioned field of view into multiple channels and reimage the multiple channels as multiple spectral signatures onto the focal plane array.
In one embodiment, a multiwavelength imager is provided. Imaging optics form an image of an object. At least one micromachined optical element (MMO) is located at or near to an image plane of the imager, providing a spectral signature for use with a focal plane array.
In one embodiment, a hyperspectral imaging system includes imaging optics that form an image of an object. A spectrometer has an array of pinholes that divide a field of view of the imaging optics into multiple channels. Dispersive optics reimage the multiple channels as multiple spectral signatures onto a focal plane array.
In one embodiment, a hyperspectral imaging system includes a lenslet array, a focal plane array, a pinhole array between the detector array and the lenslet array. The pinhole array having a different pitch than the lenslet array and aligned such that each lenslet of the lenslet array corresponds to a pinhole of the pinhole array. The lenslet array is moveable to define where an object is viewed by the imaging system. A spectrometer reimages multiple channels from the lenslet array as multiple spectral signatures onto the detector array.
In one embodiment, a hyperspectral imager includes the improvement of at least one zoom lens for selecting a variable field of view of the imager and a variable dispersion element for selecting dispersion for spectral signatures for the imager.
In one embodiment, a hyperspectral imager of the type that forms a hyperspectral data cube includes the improvement of at least one zoom collimating or relay lens that variably adjusts spectral and spatial resolution of the hyperspectral data cube.
A hyperspectral imaging system is disclosed herein which may achieve high instrument resolution by recording three-dimensions, two spatial dimensions (x and y) and a spectral or color dimension (λ), simultaneously. Further, the hyperspectral imager may be handheld and operate to disperse and refocus an image without using moving parts. The imaging optics may for example image faster than at least f/5.
A hyperspectral imaging system 100 is shown in
Spectrometer 106 divides the image from imaging optics 104 into multiple channels, where each channel forms a pupil image that is focused as a spot 400 in an image plane 4-4 of lenslet array 102, as shown in
Those skilled in the art, upon reading and fully appreciating this disclosure, will appreciate that elements 108, 112 of
As illustrated in
The images received by focal plane array 114 are captured by a computer processor 116 and both the location of an image and the spectral information for that location are processed into a three-dimensional data set denoted herein as a hyperspectral data cube 118. The data are collected in parallel and may be saved to memory and/or viewed in real time in any of the several hundred wavebands recorded. Data cubes 118 are collected at the speed of the digital detector array, typically limited by its internal digital clock. Thus data cubes may be read, for example, at a rate between 1-1000 data cubes per second with a spectral resolution in a range of about 1-50 nm, for example.
As illustrated in
Referring again to
The use of MMO's may reduce the overall size and complexity of the hyperspectral imaging system, as well as increase the durability of the instrument using the hyperspectral imaging system, because there are no moving parts. Since the MMO's are micromachined they are ideally suited for manufacturing in silicon for use in infrared imagers. Alternatively, using a low cost replicating technique, the MMO's may be molded into epoxy on glass, for use in the visible waveband. Gratings may be applied to the MMO's during the molding process or by chemical etching, photolithography and the like.
Multiple hyperspectral imagers may be used to cover a large field of view. For example, the exterior of a surveillance plane may be covered with multiple hyperspectral imagers. Data from the multiple imagers may be compiled into one comprehensive data set for viewing and analysis.
Alternatively, a large-scale hyperspectral imager may be fabricated according to the present instrumentalities. For example, a large-scale imager may be used in aerial or satellite applications. The costs of fabricating and transporting an imager as herein disclosed may be less than similar costs associated with a traditional hyperspectral imaging system due to the decreased number of optical components and weight thereof.
A large degree of flexibility is available where, for example, imaging optics, lenslet arrays, pinhole arrays, detectors, filters, and the like may be interchanged as necessary for a desired application of the hyperspectral imaging system. In one embodiment, illustrated in
It is also possible that lenses 600, that are not coupled with gratings 704 or prisms 706, may be utilized in a MMO wheel 1300. It may then be desirable to vary the amount of dispersion to accommodate various lens sizes. For example, dispersive element(s) 110 may be rotated to increase dispersion when large lenses 600 are used and decrease dispersion when small lenses 600 are used to sample an image. Zoom lenses may also be used beneficially with differing MMOs within the hyperspectral imaging system.
Object identification, which is more than mere recognition, may be performed by software to distinguish objects with specific spatial and spectral signatures. For example, materials from which objects in the image are made may be spectrally distinguished, e.g., in the visible range, paint on an enemy tank may be distinguished from paint on a friendly tank, while in the infrared region, a water treatment plant may be distinguished from a chemical weapons factory. The software may be trained to color code or otherwise highlight elements of the image with particular spatial and/or spectral signatures.
Certain changes may be made in the systems and methods described herein without departing from the scope hereof. It should thus be noted that the matter contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following claims are intended to cover all generic and specific features described herein, as well as all statements of the scope of the present method and system, which, as a matter of language, might be said to fall there between.
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|U.S. Classification||356/328, 356/326|
|Cooperative Classification||G01J3/0229, G02B5/045, G01J3/0256, G02B27/1066, G01J3/0235, G02B3/0056, G01J3/2803, G01J3/0286, G02B26/0883, G01J5/061, G02B3/08, G01J3/0262, G02B27/123, G01J3/021, G01J3/0294, G01J3/14, G01J3/0208, G01J3/02, G01J3/0205, G02B27/143, G01J3/36, G01J3/2823|
|European Classification||G02B27/14F, G01J3/02T, G02B27/10K, G01J3/28B, G02B26/08R2, G02B27/12L, G01J3/02N, G01J3/02B, G01J3/02D, G01J3/02B2, G01J3/02B1, G01J3/02C, G01J3/02B10, G01J3/02B8, G01J3/36, G01J5/06B, G01J3/14, G01J3/02, G01J3/28D, G02B3/08, G02B5/04A, G02B3/00A3S|
|Dec 21, 2005||AS||Assignment|
Owner name: BODKIN DESIGN AND ENGINEERING LLC, MASSACHUSETTS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BODKIN, ANDREW;SHEINIS, ANDREW;NORTON, ADAM;REEL/FRAME:017390/0229;SIGNING DATES FROM 20040901 TO 20040903