Hyperspectral imager

• US 20040090623A1
• Filed: 11/07/2002
• Published: 05/13/2004
• Est. Priority Date: 11/07/2002
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Richman, Isaac
• Granted Patent: US 6,813,018 B2
• Time in Patent Office: Days
• US Class Current: 356/328
• 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 3/0243 having a through-hole enabling the optical element to fulfil an additional optical function, e.g. a mirror or grating having a throughhole for a light collecting or light injecting optical fiber
• CPC Class Codes: G01J 3/04 Slit arrangements slit adjustment
• CPC Class Codes: G01J 3/2823 Imaging spectrometer

Abstract

The hyperspectral imager includes a diffraction grating, a collecting reflecting element and a reimaging system. The diffraction grating has an entrance slit formed at an entrance slit location therein. The entrance slit has a long dimension oriented in a y-direction. The entrance slit transmits the radiation from a slice of an incoming scene image. The collecting reflecting element receives the transmitted radiation of the incoming scene image and reflects the transmitted radiation to a diffractive surface of the diffraction grating. Grooves on the diffractive surface are substantially parallel to the y-direction. The reimaging system receives radiation diffracted by the diffractive surface. The reimaging system produces a spectral image of the entrance slit at a focal surface. The spectral image provides a spectrum of radiation propagating through the entrance slit into the hyperspectral imager such that the spectrum of radiation from a first region in the y-direction can be distinguished from the spectra of radiation from other regions in the y-direction.

Claims

1. A hyperspectral imager, comprising:

a) a diffraction grating having an entrance slit formed at an entrance slit location therein, said entrance slit having a long dimension oriented in a y-direction, said entrance slit for transmitting the radiation from a slice of an incoming scene image;

b) a collecting reflecting element for receiving said transmitted radiation of the incoming scene image and reflecting said transmitted radiation to a diffractive surface of said diffraction grating, grooves on said diffractive surface being substantially parallel to said y-direction;

c) a reimaging system for receiving radiation diffracted by said diffractive surface, said reimaging system for producing a spectral image of said entrance slit at a focal surface,

wherein said spectral image provides a spectrum of radiation propagating through said entrance slit into the hyperspectral imager, such that the spectrum of radiation from a first region in the y-direction can be distinguished from the spectra of radiation from other regions in the y-direction.

2. The hyperspectral imager of claim 1, wherein said entrance slit is formed at a substantially central location of said diffraction grating.

3. The hyperspectral imager of claim 1, wherein said slit has a substantially rectangular shape.

4. The hyperspectral imager of claim 1, wherein said slit has a curved shape.

5. The hyperspectral imager of claim 1, wherein said slit lies on a substantially planar surface.

6. The hyperspectral imager of claim 1, wherein said slit lies on a curved surface.

7. The hyperspectral imager of claim 1, wherein said diffraction grating comprises a reflection diffraction grating.

8. The hyperspectral imager of claim 1, wherein said diffraction grating comprises a transmitting diffraction grating.

9. The hyperspectral imager of claim 1, wherein said diffraction grating has a substantially planar surface.

10. The hyperspectral imager of claim 1, wherein said diffraction grating has a concave surface.

11. The hyperspectral imager of claim 1, wherein said diffraction grating has a convex surface.

12. The hyperspectral imager of claim 1, wherein said collecting reflecting element comprises a substantially planar surface.

13. The hyperspectral imager of claim 1, wherein said collecting reflecting element comprises a reflecting curved surface.

14. The hyperspectral imager of claim 1, wherein said collecting reflecting element comprises a reflecting curved surface having a paraboloidal shape.

15. The hyperspectral imager of claim 1, wherein said collecting reflecting element incorporates refractive components.

16. The hyperspectral imager of claim 1, wherein said reimaging system comprises a set of reflective reimaging elements.

17. The hyperspectral imager of claim 1, wherein said reimaging system comprises a set of refractive reimaging elements.

18. The hyperspectral imager of claim 1, wherein said reimaging system comprises a set of reimaging elements comprising both reflective and refractive reimaging elements.

19. The hyperspectral imager of claim 1, wherein said reimaging system comprises a set of reimaging elements comprising a three mirror anastigmat.

20. The hyperspectral imager of claim 1, wherein said focal surface is substantially planar.

21. The hyperspectral imager of claim 1, wherein said focal surface is curved.

22. A method for hyperspectral imaging, comprising the steps of:

a) transmitting radiation from a slice of an incoming scene image through an entrance slit formed at an entrance slit location of a diffraction grating, said entrance slit having a long dimension oriented in a y-direction;

b) receiving said transmitted radiation via a collecting reflecting element and reflecting said transmitted radiation to a diffractive surface of said diffraction grating, grooves on said diffractive surface being substantially parallel to said y-direction;

c) receiving radiation diffracted by said diffractive surface and producing a spectral image of said entrance entrance slit at a focal surface,

wherein said spectral image provides a spectrum of radiation propagating through said entrance slit into the hyperspectral imager, such that the spectrum of radiation from a first region in the y-direction can be distinguished from the spectra of radiation from other regions in the y-direction.