Spectral filter for optical sensor

• US 20070210244A1
• Filed: 03/09/2006
• Published: 09/13/2007
• Est. Priority Date: 03/09/2006
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Halvis, James, McKee, Richard
• Granted Patent: US 7,468,504 B2
• Time in Patent Office: Days
• US Class Current: 250/226
• CPC Class Codes: G01J 2003/2826 Multispectral imaging, e.g. filter imaging
• CPC Class Codes: G01J 3/021 using plane or convex mirrors, parallel phase plates, or particular reflectors
• CPC Class Codes: G01J 3/08 Beam switching arrangements
• 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

Abstract

The present invention provides a spectral filter for an optical sensor. The spectral filter includes a substrate having a focus region and a defocus region, a panchromatic filter region disposed on the focus region of the substrate and a multi-spectral filter region disposed on the defocus region of the substrate. The panchromatic filter region includes a plurality of panchromatic pixels, while the multi-spectral filter region includes a plurality of multi-spectral pixels. Each of the multi-spectral pixels includes a plurality of color pixels.

Claims

1. A spectral filter for an optical sensor, comprising:

a substrate having a focus region and a defocus region;

a panchromatic filter region, disposed on the focus region of the substrate, including a plurality of panchromatic pixels; and

a multi-spectral filter region, disposed on the defocus region of the substrate, including a plurality of multi-spectral pixels, each multi-spectral pixel having a plurality of color pixels.

2. The spectral filter of claim 1, wherein the focus region and the defocus region have different thicknesses.

3. The spectral filter of claim 1, wherein the focus region and the defocus region are different materials.

4. The spectral filter of claim 1, wherein the defocus region includes a diffusing layer.

5. The spectral filter of claim 1, wherein the plurality of color pixels are responsive to a plurality of different spectral bands within the infrared spectrum.

6. The spectral filter of claim 1, wherein the plurality of color pixels are responsive to a plurality of different spectral bands within the visible and near infrared spectrum.

7. The spectral filter of claim 6, wherein the panchromatic pixels are uniformly sized, the multi-spectral pixels are uniformly sized and the multi-spectral pixel size is larger than, and an integer multiple of, the panchromatic pixel size.

8. The spectral filter of claim 7, wherein each multi-spectral pixel includes four uniformly-sized color pixels the same size as the panchromatic pixel.

9. The spectral filter of claim 8, wherein the four color pixels are responsive to the blue, green, red and near infrared spectral bands, respectively.

10. An optical sensor, comprising:

an optical assembly having at least one steering mirror, at least one lens and at least one focal plane;

an imaging array disposed at the focal plane; and

a spectral filter, proximate to the imaging array, including;

a panchromatic filter region having a plurality of panchromatic pixels and a panchromatic resolution; and

a multi-spectral filter region having a plurality of multi-spectral pixels and a multi-spectral resolution less than the panchromatic resolution, each of said multi-spectral pixels having a plurality of color pixels.

11. The optical sensor of claim 10, wherein the panchromatic filter region is disposed on a focus region of a substrate and the multi-spectral filter region is disposed on a defocus region of the substrate.

12. The optical sensor of claim 11, wherein the focus region and the defocus region have different thicknesses.

13. The optical sensor of claim 11, wherein the focus region and the defocus region are different materials.

14. The optical sensor of claim 11, wherein the defocus region includes a diffusing layer.

15. The optical sensor of claim 10, wherein the panchromatic pixels are uniformly sized, the multi-spectral pixels are uniformly sized, the panchromatic resolution is an integer multiple of the multi-spectral resolution and each multi-spectral pixel includes four uniformly-sized color pixels responsive to the blue, green, red and near infrared spectral bands, respectively, the color pixel size being the same as the panchromatic pixel size.

16. A method for simultaneously acquiring overlaid panchromatic and multi-spectral images over the complete field-of-view of an optical sensor including a steering mirror, an imaging array and a spectral filter having a panchromatic filter region and a multi-spectral filter region, the method comprising:

moving the steering mirror one-half of the field-of-view;

integrating a panchromatic image, acquired through the panchromatic filter region by the imaging array, over one-half of the field-of-view;

integrating a multi-spectral image, acquired through the multi-spectral filter region by the imaging array, over one-half of the field-of-view;

moving the steering mirror one-half of the field-of-view;

integrating a panchromatic image, acquired through the panchromatic filter region by the imaging array, over one-half of the field-of-view; and

integrating a multi-spectral image, acquired through the multi-spectral filter region by the imaging array, over one-half of the field-of-view.

17. The method according to claim 16, wherein a panchromatic integration time and a multi-spectral integration time are different.

18. The method according to claim 16, wherein the multi-spectral image includes a plurality of multi-spectral bands, wherein at least one multi-spectral band integration time is different than the other multi-spectral band integration times.