Computer controlled, 3-CCD camera, airborne, variable interference filter imaging spectrometer system

• US 5,790,188 A
• Filed: 09/07/1995
• Issued: 08/04/1998
• Est. Priority Date: 09/07/1995
• Status: Expired due to Term

• Current Assignee: KEYW Corporation
• Original Assignee: Flight Landata, Inc. (The Keyw Corporation)
• Inventors: Sun, Xiuhong
• Primary Examiner(s): Britton, Howard W.
• Assistant Examiner(s): Le, Vu
• Application Number:
  US08/524,864
• Time in Patent Office: 1,062 Days
• Field of Search: 348/144, 348/135, 348/31, 348/42, 348/143, 348/145, 348/147, 356/328, 356/301, 250/339
• US Class Current: 348/144
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G01J 3/2823 Imaging spectrometer

Abstract

A spectrally-filtered, miniature, imaging spectrometer system for airborne remote sensing data acquisition with a two dimensional field of view. Synchronized CCD-imager sensor modules or cameras are aligned to a common field of view. One sensor module has a visible range variable interference filter on its surface and a second module has a near-infrared range variable interference filter on its surface. Video data from the three sensor modules is combined and recorded on a single analog or digital recorder. Futher, such video data is monitored by a computer and used to control the shutter speed of each of the three sensor modules. Wavelength spectral image data and directional spectral image data are acquired by a single pass over a target area. Post-processing of such data produces reconstructed track-recovery-images extracted from a sequence of video frames for the spectral regions of interest at a fixed column position to produce multiple bands of monochrome images.

Claims

1. An imaging spectrometer system comprising:

means having at least one variable interference filter for acquiring spectral images over a predetermined spectral range;

means positioned adjacent to said spectral images acquiring means for acquiring video graphic images for obtaining directional spectral data;

means for synchronizing said spectral images acquiring means and said video graphic images acquiring means to enable acquiring said spectral images and said video graphic images simultaneously;

means coupled to outputs of said spectral images acquiring means and said video graphic images acquiring means for conditioning said outputs for recording and processing; and

means coupled to said spectral images acquiring means and said video graphic acquiring means for controlling a shutter speed of said spectral images acquiring means and said video graphic images acquiring means.

2. The imaging spectrometer system as recited in claim 1 wherein said variable interference filter acquires spectral images over said predetermined spectral range including a visible spectral range and a near-infrared spectral range.

3. The imaging spectrometer system as recited in claim 1 wherein said spectral images acquiring means comprises said variable interference filter positioned contiguous to a CCD sensor.

4. The imaging spectrometer system as recited in claim 1 wherein said spectral images acquiring means and said video graphic acquiring means are aligned to a common field of view.

5. The imaging spectrometer system as recited in claim 1 wherein said directional spectral data obtained from said video graphics acquiring means corrects said spectral images from said spectral images acquiring means by removing slant errors from said spectral images.

6. The imaging spectrometer system as recited in claim 1 wherein said means for controlling a shutter speed of said spectral images acquiring means and said video graphics images acquiring means includes monitoring said outputs by said conditioning means to control the spectral intensity impinging on a CCD of said spectral images acquiring means and said video graphics images acquiring means.

7. The imaging spectrometer system as recited in claim 1 wherein said conditioning means further comprises means for generating global positioning system information.

8. The imaging spectrometer system as recited in claim 1 wherein said conditioning means comprises means for converting said outputs to a single composite video signal for recording on an analog video recorder.

9. The imaging spectrometer system as recited in claim 1 wherein said conditioning means comprises means for digitizing said outputs to enable storing said outputs in a digital format.

10. The imaging spectrometer system as recited in claim 1 wherein said conditioning means comprises computer means for controlling the conditioning of said outputs from said spectral images acquiring means and said video graphic images acquiring means.

11. An imaging spectrometer system comprising:

first camera means having a variable interference filter for acquiring spectral images in a visible spectral range;

second camera means having a variable interference filter for acquiring spectral images in a near-infrared spectral range;

third camera means for acquiring video graphic images, said video graphic images being used to obtain directional spectral data;

means for synchronizing said first camera means, said second camera means and said third camera means to acquire said images simultaneously, said first camera means, said second camera means and said third camera means being aligned to a common field of view;

means coupled to outputs of said first camera means, said second camera means and said third camera means for conditioning said outputs for recording and processing; and

means coupled to said first camera means, said second camera means and said third camera means for controlling a shutter speed of said first camera means, said second camera means, and said third camera means.

12. The imaging spectrometer system as recited in claim 11 wherein said conditioning means comprises means for transforming said outputs from a three-channel format to a single video signal stream.

13. The imaging spectrometer system as recited in claim 11 wherein said system comprises means coupled to said conditioning means for storing said composite video signal on an analog video recorder.

14. The imaging spectrometer system as recited in claim 13 wherein said system comprises means coupled to said storing means for post-processing said composite video signals.

15. The imaging spectrometer system as recited in claim 11 wherein said conditioning means further comprises means for digitizing said outputs of said first camera means, said second camera means and said third camera means for storing said outputs in a digital format.

16. The imaging spectrometer system as recited in claim 11 wherein said directional spectral data obtained from said third camera means corrects said spectral images from said first camera means and said second camera means by removing slant errors from said spectral images.

17. The imaging spectrometer system as recited in claim 11 wherein said conditioning means comprises a data acquisition computer means for controlling the acquisition and storage of said outputs from said first camera means, said second camera means, and said third camera means.

18. The imaging spectrometer system as recited in claim 11 wherein said means for controlling said shutter speed of said first camera mans, said second camera means and said third camera means includes monitoring said outputs by said conditioning means to control the spectral intensity impinging on a CCD of said first camera means, said second camera means and said third camera means.

19. The imaging spectrometer system as recited in claim 11 wherein said visible spectral range variable interference filter is aligned and attached to a CCD sensor in said first camera means.

20. The imaging spectrometer system as recited in claim 11 wherein said near infrared spectral range variable interference filter is positioned, aligned and attached to a CCD sensor in said second camera means.

21. The imaging spectrometer system as recited in claim 11 wherein said conditioning means further comprises means for generating global positioning system information.

22. A method of providing an imaging spectrometer system comprising the steps of:

acquiring spectral images over a predetermined spectral range with means having at least one variable interference filter;

acquiring video graphic images with means positioned adjacent to said spectral images acquiring means to obtain directional spectral data;

synchronizing said spectral images acquiring means and said video graphic images acquiring means to enable acquiring said spectral images and said video graphic images simultaneously;

conditioning outputs of said spectral images acquiring means and said video graphic images acquiring means for recording and processing said outputs with means coupled to said outputs; and

controlling a shutter speed of said spectral images acquiring means and said video graphic images acquiring means.

23. The method as recited in claim 22 wherein said step of acquiring spectral images over a predetermined spectral range with said variable interference filter includes the step of acquiring spectral images over a visible spectral range and a near-infrared spectral range.

24. The method as recited in claim 22 wherein said step of acquiring spectral images with means having at least one variable interference filter comprises the step of positioning said filter contiguous to a CCD sensor of said acquiring means.

25. The method as recited in claim 22 wherein said spectral imaging acquiring means and said video graphic images acquiring means are aligned to a common field of view.

26. The method as recited in claim 22 wherein said step of acquiring video graphic images to obtain directional spectral data comprises the step of correcting said spectral images with said directional spectral data by removing slant errors from said spectral images.

27. The method as recited in claim 22 wherein said step of controlling a shutter speed of said spectral imaging acquiring means and said video graphic images acquiring means comprises the step of monitoring said outputs by said conditioning means to control the spectral intensity impinging on a CCD of said spectral images acquiring means and said video graphic images acquiring means.

28. The method as recited in claim 22 further comprises the step of providing global positioning system information for use with said spectral images.

29. The method as recited in claim 22 wherein said step of conditioning outputs of said spectral images acquiring means and said video graphic images acquiring means comprises the step of transforming said outputs to a single composite video signal for recording on an analog video recorder.

30. The method as recited in claim 22 wherein said step of conditioning outputs of said spectral images acquiring means and said video graphic images acquiring means comprises the step of digitizing said outputs to enable storing said outputs in a digital format.