Coded Aperture Snapshot Spectral Imager and Method Therefor

• US 20120105844A1
• Filed: 12/30/2011
• Published: 05/03/2012
• Est. Priority Date: 04/07/2009
• Status: Active Grant

• Current Assignee: Applied Quantum Technologies, Inc.
• Original Assignee: Applied Quantum Technologies, Inc.
• Inventors: Brady, David Jones, McCain, Scott Thomas, Portnoy, Andrew David
• Granted Patent: US 8,553,222 B2
• Time in Patent Office: Days
• US Class Current: 356/310
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/0229 using masks, aperture plates, spatial light modulators or spatial filters, e.g. reflective filters
• CPC Class Codes: G01J 3/2803 using photoelectric array detector
• CPC Class Codes: G01J 3/2823 Imaging spectrometer

Abstract

The present invention enables snap-shot spectral imaging of a scene at high image generation rates. Light from the scene is processed through an optical system that comprises a coded-aperture. The optical system projects a plurality of images, each characterized by only one of a plurality of spectral components, onto a photodetector array. The plurality of images is interspersed on the photodetector array, but no photodetector receives light characterized by more than one of the plurality of spectral components. As a result, computation of the spatio-spectral datacube that describes the scene is simplified. The present invention, therefore, enables rapid spectral imaging of the scene.

Claims

1-21. -21. (canceled)

22. A method for providing a spectral image of a scene that includes a plurality of object pixels that are arranged in a two-dimensional arrangement, the method comprising:

(1) projecting a plurality of first images of the scene onto a first image plane, wherein the plurality of first images are formed by operations comprising;

(a) providing a plurality of sub-images, each sub-image being based on light from the scene that comprises a plurality of spectral components, wherein each sub-image corresponds to a different object pixel, and wherein the plurality of sub-images and the plurality of object pixels are spatially correlated; and

(b) projecting the plurality of sub-images onto a first image plane such that the spectral components of each sub-image are spatially dispersed along a first direction; and

(2) receiving the plurality of first images at a photodetector array that is located at the first image plane, wherein each photodetector in the photodetector array receives light that is characterized by only one of the plurality of spectral components.

23. The method of claim 22 wherein the plurality of sub-images is provided by operations comprising imaging the scene onto a coded aperture, wherein the coded aperture is located at a second image plane, and wherein the coded aperture transmits the plurality of sub-images such that each of the plurality of sub-images comprises the plurality of spectral components.

24. The method of claim 23 further comprising providing the coded aperture, wherein the coded aperture comprises an array of fields, and wherein each field has n rows of regions aligned with the first dimension and n columns of regions aligned with a second dimension, where n is the number of spectral components in the plurality of spectral components, and wherein each row comprises 1 transmissive region and (n−

1) non-transmissive regions, and further wherein no two transmissive regions within the coded aperture are contiguous.

25. The method of claim 23 wherein the plurality of sub-images is projected onto the first image plane by operations comprising imaging the coded aperture onto the first image plane through a disperser that disperses the spectral components of each of the plurality of sub-images along the first dimension.

26. The method of claim 25 wherein the coded aperture is imaged onto the first image plane by a plurality of imaging elements, and wherein each of the plurality of imaging elements images a different area of the coded aperture onto the first image plane.

27. A method for providing a spectral image of a scene that includes a plurality of object pixels arranged in a two-dimensional arrangement, the method comprising:

(1) providing a plurality of first images of the scene, the plurality of first images being provided by operations comprising;

(a) providing a first coded aperture that is located at a first image plane;

(b) forming a first image at the first coded aperture, the first image being formed by imaging the scene through a first disperser that induces a first dispersion along a first dimension;

(c) transmitting at least a portion of the first image through the coded aperture; and

(d) imaging the coded aperture onto a second image plane through a second disperser, wherein the second disperser removes the induced first dispersion; and

(2) receiving the plurality of first images at a photodetector array that is located at the second image plane, wherein each photodetector in the photodetector array receives light that is characterized by only one of the plurality of spectral components.

28. The method of claim 27 further comprising providing the coded aperture, wherein the coded aperture comprises an array of fields, and wherein each field has n rows of regions aligned with the first dimension and n columns of regions aligned with a second dimension, where n is the number of spectral components in the plurality of spectral components, and wherein each row comprises 1 transmissive region and (n−

1) non-transmissive regions, and further wherein no two transmissive regions within the coded aperture are contiguous.

29. The method of claim 27 wherein the coded aperture is imaged onto the second image plane by a plurality of imaging elements, and wherein each of the plurality of imaging elements images a different area of the coded aperture onto the second image plane.

30. A method for providing a spectral image of a scene that includes a plurality of object pixels arranged in a two-dimensional arrangement, the method comprising:

(1) providing a plurality of first images of the scene, the plurality of first images being provided by operations comprising;

(a) imaging the scene onto a first coded aperture that is located at a first image plane;

(b) imaging the first coded aperture onto a second coded aperture located at a second image plane, wherein the first coded aperture is imaged onto the second coded aperture through a first disperser that induces a first dispersion along a first dimension; and

(c) imaging the second coded aperture onto a third image plane, wherein the second coded aperture is imaged onto the third image plane through a second disperser, and wherein the second disperser is less dispersive than the first disperser; and

(2) receiving the plurality of first images at a photodetector array that is located at the third image plane, wherein each photodetector in the photodetector array receives light that is characterized by only one of the plurality of spectral components.

31. The method of claim 30 wherein the first coded aperture is imaged onto the second coded aperture by a first plurality of imaging elements, and wherein each of the first plurality of imaging elements images a different area of the first coded aperture at the second coded aperture, and wherein the second coded aperture is imaged onto the first image plane by a second plurality of imaging elements, and further wherein each of the second plurality of imaging elements images a different area of the second coded aperture onto the first image plane.

32. The method of claim 30 further comprising providing the coded aperture, wherein the coded aperture comprises an array of fields, and wherein each field has n rows of regions aligned with the first dimension and n columns of regions aligned with a second dimension, where n is the number of spectral components in the plurality of spectral components, and wherein each row comprises 1 transmissive region and (n−

1) non-transmissive regions, and further wherein no two transmissive regions within the coded aperture are contiguous.