Gimbaled multispectral imaging system and method

Patent metadata

Field	Value
Publication number	US-9244264-B1
Application number	US-201414303355-A
Country	US
Kind code	B1
Filing date	Jun 12, 2014
Priority date	Jun 14, 2013
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

A gimbaled multispectral imaging system and method is described herein. In an general embodiment, the gimbaled multispectral imaging system has a cross support that defines a first gimbal axis and a second gimbal axis, wherein the cross support is rotatable about the first gimbal axis. The gimbaled multispectral imaging system comprises a telescope that fixed to an upper end of the cross support, such that rotation of the cross support about the first gimbal axis causes the tilt of the telescope to alter. The gimbaled multispectral imaging system includes optics that facilitate on-gimbal detection of visible light and off-gimbal detection of infrared light.

First claim

What is claimed is:

1. A gimbaled multispectral imaging system comprising:
a telescope, the telescope having a proximal end and a distal end, an optical axis extending from the proximal end to the distal end, the telescope comprising:
a primary mirror positioned proximate to the proximal end of the telescope, the primary mirror has a first focal point on the optical axis of the telescope;
a secondary mirror positioned proximate to the distal end of the telescope, the secondary mirror has a second focal point on the optical axis of the telescope;
a beam splitter positioned between the primary mirror and the secondary mirror and on the optical axis of the telescope, the beam splitter configured to partition the light reflected by the secondary mirror into first light and second light, wherein the first light passes through the beam splitter along the optical axis of the telescope and the second light is reflected by the beam splitter along a gimbal axis, the gimbal axis orthogonal to the optical axis of the telescope;
a first detector that is configured to generate a first value based upon the first light; and
a second detector that is configured to generate a second value based upon the second light.

2. The gimbaled multispectral imaging system of claim 1 , wherein the first light comprises light with a wavelength between 400 nanometers and 1.2 micrometers.

3. The gimbaled multispectral imaging system of claim 2 , wherein the second light comprises light with a wavelength between 1.4 micrometers and 12 micrometers.

4. The gimbaled multispectral imaging system of claim 1 , further comprising:
a hollow cross support that defines the gimbal axis and a second gimbal axis, the cross support rotatable about the second gimbal axis, the cross support comprises an upper end, wherein the telescope is attached to the cross support at the upper end; and
a fold mirror positioned at the intersection of the first gimbal axis and the second gimbal axis in an interior of the cross support, the fold mirror redirecting the second light from the first gimbal axis to the second gimbal axis.

5. The gimbaled multispectral imaging system of claim 4 , further comprising a cooling element positioned off-gimbal, the cooling element configured to cool a cold space to cryogenic temperatures, the cold space comprises the second detector.

6. The gimbaled multispectral imaging system of claim 5 , further comprising:
a second beam splitter positioned in the cold space, the second beam splitter configured to receive the second light and partition the second light into third light and fourth light, the third light having wavelengths in a third range of wavelengths, the fourth light having wavelengths in a fourth range of wavelengths, wherein the second detector generates the second value based upon the third light; and
a third detector that receives the fourth light and is configured to generate a third value based upon the fourth light.

7. The gimbaled multispectral imaging system of claim 6 , wherein the third range of wavelengths and the fourth range of wavelengths are non-overlapping.

8. The gimbaled multispectral imaging system of claim 4 , wherein the hollow cross support comprises a lower end, the system further comprising an inertial reference unit that is attached at the lower end of the cross support.

9. The gimbaled multispectral imaging system of claim 8 , the system further comprising first electronics attached at the lower end of the hollow cross support, the first electronics configured to generate an image based upon the first value generated by the first detector.

10. The gimbaled multispectral imaging system of claim 1 , further comprising an aperture stop positioned adjacent to the primary mirror and between the primary mirror and the secondary mirror, the aperture stop having a diameter of between ten centimeters and one meter.

11. The gimbaled multispectral imaging system of claim of claim 1 , the telescope further comprising a filter positioned on the optical axis of the telescope between the beam splitter and the first detector, the filter configured to receive the first light and generate filtered light based upon the first light, the first detector generates the first value based upon the filtered light.

12. The gimbaled multispectral imaging system of claim 11 , the filter being a filter wheel.

13. The gimbaled multispectral imaging system of claim 11 , the filter being a fixed filter.

14. A method performed by a gimbaled multispectral imaging system, the method comprising:
receiving light, the light comprises first light having a first range wavelengths and second light having a second range wavelengths, the first range of wavelengths being different from the second range wavelengths, wherein the first range of wavelengths is in the visible spectrum and the very near infrared spectrum, and the second range of wavelengths is in the infrared spectrum;
reflecting and focusing the light in a first direction;
responsive to reflecting and focusing the light in the first direction, reflecting and focusing the light in a second direction, the second direction opposes the first direction;
responsive to reflecting and focusing the light in the second direction, partitioning the light into the first light and the second light, wherein partitioning the light comprises:
directing the first light in the second direction; and
directing the second light in a third direction, the third direction being different from the first direction and the second direction;

responsive to partitioning the light into the first light and the second light, directing the second light to a cold space, the cold space cooled by one of a cryogenic cooler or a thermoelectric cooler;
generating a first value that is indicative of an intensity of the first light; and
generating a second value that is indicative of an intensity of the second light, wherein the generating of the second value occurs in the cold space, and wherein the one of the cryogenic cooler or the thermoelectric cooler is mechanically decoupled from the cold space.

15. A method performed by a gimbaled multispectral imaging system, the method comprising:
receiving light, the light comprises first light having a first range wavelengths and second light having a second range wavelengths, the first range of wavelengths being different from the second range wavelengths;
reflecting and focusing the light in a first direction;
responsive to reflecting and focusing the light in the first direction, reflecting and focusing the light in a second direction, the second direction opposes the first direction;
responsive to reflecting and focusing the light in the second direction, partitioning the light into the first light and the second light, wherein partitioning the light comprises:
directing the first light in the second direction; and
directing the second light in a third direction, the third direction being different from the first direction and the second direction;

generating a first value that is indicative of an intensity of the first light; and
generating a second value that is indicative of an intensity of the second light, wherein the generating of the first value is performed on-gimbal, and wherein the generating of the second value is performed off-gimbal.

Assignees

• Sandia Corp

Inventors

• Brown Kevin H
• Crollett Seferino
• Henson Tammy D
• Napier Mathew
• Stromberg Peter G

Classifications

• G02B17/0808 Primary

  on-axis systems with at least one of the mirrors having a central aperture · CPC title

• G02B23/12 Primary

  with means for image conversion or intensification · CPC title

• G02B23/02

  involving prisms or mirrors (G02B23/14 takes precedence) · CPC title

• G02B23/16

  Housings; Caps; Mountings; Supports, e.g. with counterweight · CPC title

• G02B17/0896

  with variable magnification or multiple imaging planes, including multispectral systems (systems with only refractive elements G02B15/14) · CPC title