Spatially corrected full-cubed hyperspectral imager

• US 7,433,042 B1
• Filed: 07/07/2007
• Issued: 10/07/2008
• Est. Priority Date: 12/05/2003
• Status: Active Grant

• Current Assignee: Surface Optics Corp.
• Original Assignee: Surface Optics Corp.
• Inventors: Catanzaro, Brian, Cavanaugh, David B., Dombrowski, Mark
• Primary Examiner(s): Lyons; Michael A.
• Assistant Examiner(s): Richey; Scott M
• Application Number:
  US11/774,599
• Time in Patent Office: 458 Days
• Field of Search: 356/419, 250/339.07
• US Class Current: 356/419
• CPC Class Codes: G01J 2003/1213 Filters in general, e.g. dichroic, band
• 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
• 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. Spectral filtering is performed by a spectral filter array positioned at the objective lens so that each sub-pixel within a super-pixel receives light that has been filtered by a bandpass or other type filter and is responsive to 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.

Claims

1. A hyperspectral imager comprising:

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

an array of spectral filters placed at the entrance pupil of the objective lens, each spectral filter element passing a band of light;

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

a micro-lens array comprising a plurality of micro-lenses, positioned between the objective lens and the detector array, each micro-lens of the micro-lens array positioned approximately at the focal plane to produce an image for one multiband detector;

wherein all detectors of one multiband detector receive substantially the same image and each detector of one multiband detector receives light from one element of the array of spectral filters.

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 micro-lens array that defines the image shape projected onto a multiband detector.