Modular imaging spectrometer assembly and method

Patent metadata

Field	Value
Publication number	US-10168209-B2
Application number	US-201715481834-A
Country	US
Kind code	B2
Filing date	Apr 7, 2017
Priority date	Apr 7, 2017
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

Aspects and embodiments are generally directed to modular imaging spectrometer assemblies and methods of operation thereof. In one example, a modular imaging spectrometer assembly includes foreoptics to receive electromagnetic radiation and produce a real exit pupil, the foreoptics having a first f-number, a first imaging spectrometer to receive and disperse the electromagnetic radiation into a first plurality of spectral bands at a first image plane, the first imaging spectrometer having a second f-number independent of the first f-number, a second imaging spectrometer separated from the first imaging spectrometer, the second imaging spectrometer to receive and disperse the electromagnetic radiation into a second plurality of spectral bands, the second imaging spectrometer having a third f-number independent of the first f-number, and at least one slit aperture positioned to receive the electromagnetic radiation from the real exit pupil and direct the electromagnetic radiation to the first and second imaging spectrometers.

First claim

What is claimed is:

1. A modular imaging spectrometer assembly comprising:
an all-reflective foreoptics assembly positioned to receive electromagnetic radiation from a scene and produce a real exit pupil, the all-reflective foreoptics assembly having a first f-number;
a first imaging spectrometer including a first all-reflective optical assembly configured to receive and disperse the electromagnetic radiation into a first plurality of spectral bands at a first image plane, the first imaging spectrometer having a second f-number that is independent of the first f-number, wherein the first all-reflective optical assembly includes:
a first plurality of collimating optics to receive and collimate the electromagnetic radiation from the at least one slit aperture to produce first collimated electromagnetic radiation,
a first dispersive element positioned to receive the first collimated electromagnetic radiation from the first plurality of collimating optics and disperse the first collimated electromagnetic radiation into the first plurality of spectral bands, and
a first plurality of focusing optics to focus the dispersed electromagnetic radiation at the first image plane;

a second imaging spectrometer spatially separated from the first imaging spectrometer, the second imaging spectrometer including a second all-reflective optical assembly configured to receive and disperse the electromagnetic radiation into a second plurality of spectral bands at a second image plane, the second imaging spectrometer having a third f-number that is independent of the first f-number, wherein the second all-reflective optical assembly includes:
a second plurality of collimating optics to receive and collimate the electromagnetic radiation from the at least one slit aperture to produce second collimated electromagnetic radiation,
a second dispersive element positioned to receive the second collimated electromagnetic radiation from the second plurality of collimating optics and disperse the second collimated electromagnetic radiation into the second plurality of spectral bands; and
a second plurality of focusing optics to focus the dispersed electromagnetic radiation at the second image plane; and

at least one slit aperture interposed between the all-reflective foreoptics assembly and the first imaging spectrometer and the second imaging spectrometer, the at least one slit aperture being positioned to receive the electromagnetic radiation from the real exit pupil and direct the electromagnetic radiation to the first imaging spectrometer and the second imaging spectrometer.

2. The modular imaging spectrometer assembly of claim 1 , wherein the second f-number and the third f-number are independent of each other.

3. The modular imaging spectrometer assembly of claim 2 , wherein each of the first f-number, second f-number, and third f-number has a different value.

4. The modular imaging spectrometer assembly of claim 1 , wherein the at least one slit aperture includes a first slit aperture configured to direct the electromagnetic radiation along a first optical path to the first imaging spectrometer and a second slit aperture configured to direct the electromagnetic radiation along a second optical path to the second imaging spectrometer.

5. The modular imaging spectrometer assembly of claim 1 , wherein the first plurality of collimating optics is a first reflective triplet and the first plurality of focusing optics is a second reflective triplet.

6. The modular imaging spectrometer assembly of claim 5 , wherein the first dispersive element is a diffraction grating.

7. The modular imaging spectrometer assembly of claim 1 , wherein the second plurality of collimating optics is a third reflective triplet and the second plurality of focusing optics is a fourth reflective triplet.

8. The modular imaging spectrometer assembly of claim 1 , wherein the first imaging spectrometer includes a first optical sensor positioned at the first image plane at configured to detect electromagnetic radiation within the long-wave infrared (LWIR) spectrum, and wherein the second imaging spectrometer includes a second optical sensor positioned at the second image plane at configured to detect electromagnetic radiation within the short-wave infrared (SWIR) spectrum.

9. A method of operating a modular all-reflective imaging spectrometer assembly, the method comprising:
receiving electromagnetic radiation from a scene with an all-reflective foreoptics assembly having a first f-number;
directing the electromagnetic radiation from a real exit-pupil of the all-reflective foreoptics assembly along a first optical path through a first slit aperture to a first imaging spectrometer and along a second optical path through a second slit aperture to a second imaging spectrometer, the first optical path being spatially separated from the second optical path;
with a first all-reflective optical assembly of the first imaging spectrometer, collimating the electromagnetic radiation to produce first collimated electromagnetic radiation, dispersing the first collimated electromagnetic radiation into a first plurality of spectral bands and focusing the first plurality of spectral bands onto a first image plane of the first imaging spectrometer, the first imaging spectrometer having a second f-number that is independent of the first f-number;
with a second all-reflective optical assembly of the second imaging spectrometer, collimating the electromagnetic radiation to produce second collimated electromagnetic radiation, dispersing the second collimated electromagnetic radiation into a second plurality of spectral bands and focusing the second plurality of spectral bands onto a second image plane of the second imaging spectrometer, the second imaging spectrometer having a third f-number that is independent of the first f-number.

10. The modular imaging spectrometer assembly of claim 9 , wherein the second f-number and the third f-number are independent of each other.

11. The modular imaging spectrometer assembly of claim 10 , wherein each of the first f-number, second f-number, and third f-number has a different value.

12. The method of claim 9 , wherein collimating the electromagnetic radiation with the first all-reflective optical assembly of the first imaging spectrometer includes passing the electromagnetic radiation through a first plurality of mirrors of a first reflective triplet, and wherein collimating the electromagnetic radiation with the second all-reflective optical assembly of the second imaging spectrometer includes passing the electromagnetic radiation through a second plurality of mirrors of a second reflective triplet.

13. The method of claim 12 , wherein focusing the first plurality of spectral bands onto the first image plane of the first imaging spectrometer includes passing the electromagnetic radiation through a third plurality of mirrors of a third reflective triplet, and wherein focusing the second plurality of spectral bands onto the second image plane of the second imaging spectrometer includes passing the electromagnetic radiation through a fourth plurality of mirrors of a fourth reflective triplet.

14. A modular all-reflective imaging spectrometer assembly comprising:
an all-reflective foreoptics assembly positioned to receive electromagnetic radiation from a scene and produce a real exit pupil, the all-reflective foreoptics assembly having a first f-number;
a first imaging spectrometer including:
a first all-reflective optical assembly configured to receive, collimate, and then disperse the electromagnetic radiation into a first plurality of spectral bands at a first image plane, t

Assignees

• Raytheon Co

Inventors

• Spencer Susan B
• Cook Lacy G
• Bullard Andrew L
• Silny John F

Classifications

• G01J3/0208 Primary

  using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction · CPC title

• G01J3/0202 Primary

  Mechanical elements; Supports for optical elements · CPC title

• G01J3/021

  using plane or convex mirrors, parallel phase plates, or particular reflectors · CPC title

• G01J2003/045

  Sequential slits; Multiple slits · CPC title

• G01J3/18

  using diffraction elements, e.g. grating (gratings per se G02B) · CPC title