Spatially corrected full-cubed hyperspectral imager

• US 7,242,478 B1
• Filed: 11/09/2004
• Issued: 07/10/2007
• Est. Priority Date: 12/05/2003
• Status: Active Grant

• Current Assignee: Surface Optics Corp.
• Original Assignee: Surface Optics Corp.
• Inventors: Catanzaro, Brian, Dombrowski, Mark
• Primary Examiner(s): Toatley, Jr.; Gregory J.
• Assistant Examiner(s): Richey; Scott M.
• Application Number:
  US10/984,561
• Time in Patent Office: 973 Days
• Field of Search: 356/419, 250/339.07
• US Class Current: 356/419
• 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 3/2803 using photoelectric array detector
• CPC Class Codes: G01J 3/2823 Imaging spectrometer
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G01N 21/25 Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands

Abstract

A hyperspectral imager that achieves accurate spectral and spatial resolution by using a micro-lens array as a series of field lenses, with each lens distributing a point in the image scene received through an objective lens across an area of a detector array forming a hyperspectral detector super-pixel. Each sub-pixel within a super-pixel has a bandpass or other type filter to pass a different band of the image spectrum. The micro-lens spatially corrects the focused image point to project the same image scene point onto all sub-pixels within a super-pixel. A color separator can be used to split the image into sub-bands, with each sub-band image projected onto a different spatially corrected detector array. A shaped limiting aperture can be used to isolate the image scene point within each super-pixels and minimize energy coupling to adjacent super-pixels.

Claims

1. A hyperspectral imager comprising:

an objective lens for producing a focused image at a focal plane;

a detector array comprising a plurality of multiband detectors, each multiband detector comprising a plurality of single band detectors;

a lens array comprising a plurality of lenses, positioned between the objective lens and the detector array, each lens of the lens array positioned approximately at the focal plane to produce an image for one multiband detector, wherein all single band detectors of one multiband detector receive substantially the same image.

2. The hyperspectral imager of claim 1 wherein the objective lens is telecentric.

3. The hyperspectral imager of claim 1 further comprising a limiting aperture positioned at the objective lens that defines the image shape projected onto a multiband detector.

4. The hyperspectral imager of claim 2 further comprising a limiting aperture positioned at the objective lens that defines the image shape projected onto a multiband detector.

5. The hyperspectral imager of claim 2 comprising a limiting aperture positioned between the objective lens and the lens array that defines the image shape projected onto a multiband detector.

6. A hyperspectral imager comprising:

an objective lens with a limiting aperture for producing a focused image at a focal plane;

a color separator with an input receiving an image from the objective lens and a plurality of outputs, wherein each output is a band-filtered sub-band of the input spectrum;

a plurality of detector arrays comprising a plurality of multiband detectors;

each detector array receiving light from one color separator output;

a plurality of lens arrays comprising a plurality of lenses positioned between a color separator output and a detector array, each lens having a collection aperture and positioned to distribute light from any point in its aperture evenly across all elements of one multiband detector.

7. A spatially corrected multiband optical detector for resolving incident energy in a plurality of discrete wavelength bands within an image comprising:

a spatial correcting lens for receiving a predefined point of the image;

a filter matrix comprising a plurality of bandpass filters of a plurality of wavelengths;

a detector comprising a plurality of picture elements (pixels), wherein each detector pixel corresponds to one bandpass filter and is positioned relative to the filter matrix wherein each detector pixel receives light passing through one bandpass filter;

wherein the correcting lens projects a point from the image through the filter matrix onto substantially all the detector picture elements;

whereby each of the plurality of detector picture elements responds to the wavelength band of the corresponding bandpass filter and all pixels covered by the filter matrix are responsive to the same point of the image.

8. A spatially corrected two-dimensional hyperspectral imager comprising:

a two-dimensional array of multiband optical detectors of claim 7;

an objective lens that focuses an image onto the correcting lens of the multiband optical detectors.

10. The spatially corrected two-dimensional hyperspectral imager of claim 8 wherein all pixels of the multiband optical detectors are part of a CMOS detector array.

9. A two-dimensional hyperspectral imager for measuring energy in a plurality of discrete wavelength bands of an image comprising:

an objective lens for receiving the image and focusing the image to a focal plane;

a color separator positioned in the path of the objective lens for separating the image into sub-bands;

a plurality of two-dimensional hyperspectral imagers each positioned to receive a sub-band image and comprising;

a detector array comprising a plurality of multiband detectors, each multiband detector comprising a plurality of single band detectors;

a lens array comprising a plurality of lenses, each lens positioned approximately at the focal plane to produce an image for one multiband detector, wherein each single band detector of one multiband detector receives substantially the same image.

11. The two-dimensional hyperspectral imager of claim 9 further comprising a limiting aperture positioned at the objective lens that defines the image shape projected onto each multiband detector.