METHOD AND APPARATUS FOR COMPENSATING FOR A PARAMETER CHANGE IN A SYNTHETIC APERTURE IMAGING SYSTEM

• US 20120218140A1
• Filed: 06/28/2010
• Published: 08/30/2012
• Est. Priority Date: 06/28/2010
• Status: Active Grant

• Current Assignee: Institut national d'optique
• Original Assignee: Institut national d'optique
• Inventors: Bergeron, Alain, Marchese, Linda
• Granted Patent: US 9,176,227 B2
• Time in Patent Office: Days
• US Class Current: 342/25.A
• CPC Class Codes: G01S 13/9005 with optical processing of the SAR signals
• CPC Class Codes: G01S 13/904 SAR modes
• CPC Class Codes: G01S 13/9054 Stripmap mode
• CPC Class Codes: G01S 15/8997 using synthetic aperture techniques
• CPC Class Codes: G01S 17/90 using synthetic aperture techniques
• CPC Class Codes: G01S 7/4004 of parts of a radar system
• CPC Class Codes: G02B 27/58 Optics for apodization or superresolution; Optical synthetic aperture systems
• CPC Class Codes: G03H 2001/046 Synthetic aperture
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction

Abstract

There is described a method for processing data generated by a synthetic aperture imaging system, comprising: receiving raw data representative of electromagnetic signals reflected by a target area to be imaged; receiving a parameter change for the synthetic aperture imaging system; digitally correcting the raw data in accordance with the parameter change, thereby compensating for the parameter change in order to obtain corrected data; and generating an image of the target area using the corrected data.

Claims

1. A method for processing data generated by a synthetic aperture imaging system, comprising:

receiving raw data representative of electromagnetic signals reflected by a target area to be imaged;

receiving a parameter change for said synthetic aperture imaging system;

digitally correcting said raw data in accordance with said parameter change, thereby compensating for said parameter change in order to obtain corrected data; and

generating an image of said target area using said corrected data.

2. The method as claimed in claim 1, wherein said receiving said parameter change comprises receiving a parameter change causing a variation of an interference pattern parameter for said synthetic aperture imaging system.

3. The method as claimed in claim 2, wherein said interference pattern parameter is one of a Fresnel zone plate focal length and a Fourier slice scaling parameter

4. The method as claimed in claim 2, wherein said correcting said raw data comprises:

determining a scaling factor using said parameter change; and

scaling said raw data in accordance with said scaling factor, thereby obtaining said corrected data.

5. The method as claimed in claim 1, wherein said receiving said parameter change comprises receiving a parameter change causing a Doppler shift for said synthetic aperture imaging system.

6. The method as claimed in claim 5, wherein said correcting said raw data comprises:

determining a phase factor corresponding to said parameter change; and

applying said phase factor to said raw data, thereby obtaining said corrected data.

7. The method as claimed in claim 1, wherein said generating said image comprises digitally generating a digital image using said corrected data.

8. The method as claimed in claim 1, wherein said generating said image comprises:

generating an incident light;

modulating said incident light in accordance with said corrected data, thereby obtaining a modulated light; and

optically processing said modulated light, thereby obtaining an optical image of said target area.

9. The method as claimed in claim 8, further comprising detecting said optical image to obtain a digital image of said target area.

10. The method as claimed in claim 5, wherein said correcting said raw data comprises:

generating an initial modulation pattern using said raw data, said initial modulation pattern comprising points organized along an azimuth axis and a range axis, each one of said points being associated with an amplitude value and a phase value;

determining an azimuth shift in accordance with said parameter change; and

translating said points of said initial modulation pattern in accordance with said azimuth shift, thereby obtaining a corrected modulation pattern.

11. The method as claimed in claim 10, wherein said generating said image comprises:

generating an incident light;

modulating said incident light in accordance with said corrected modulation pattern, thereby obtaining a modulated light; and

optically processing said modulated light, thereby obtaining an optical image of said target area.

12. The method as claimed in claim 11, further comprising detecting said optical image to obtain a digital image of said target area.

13. The method as claimed in claim 2, wherein said parameter change comprises a change of one of a pulse repetition frequency, a range sampling frequency, and a slant range distance.

14. The method as claimed in claim 5, wherein said parameter change comprises a change of one of a squint angle and an eccentricity of a platform orbit.

15. The method as claimed in claim 1, wherein said receiving said raw data comprises receiving said raw data from one of a synthetic aperture radar system, a synthetic aperture sonar system, a synthetic aperture lidar system, a synthetic aperture terahertz system, and a synthetic aperture infrared system.

16. A system for generating a synthetic aperture image of a target area, comprising:

a memory for storing raw data representative of electromagnetic signals reflected by said target area and a parameter change for said synthetic aperture imaging system;

a raw data correcting module adapted to correct said raw data in accordance with said parameter change in order compensate for said parameter change and obtain corrected data; and

an image generator adapted to generate an image of said target area using said corrected data.

17. The system as claimed in claim 16, wherein said parameter change comprises a parameter change causing a variation of an interference pattern parameter.

18. The system as claimed in claim 17, wherein said interference pattern parameter comprises one of a Fresnel zone plate focal length and a Fourier slice scaling parameter.

19. The system as claimed in claim 17, wherein said raw data correcting module is adapted to:

determine a scaling factor using said parameter change; and

scale said raw data in accordance with said scaling factor in order to obtain said corrected data.

20. The system as claimed in claim 16, wherein said parameter change comprises a parameter change causing a Doppler shift.

21. The system as claimed in claim 20, wherein said raw data correcting module is adapted to:

determine a phase factor corresponding to said parameter change; and

apply said phase factor to said raw data in order to obtain said corrected data.

22. The system as claimed in claim 16, wherein said image generator comprises a processing unit adapted to digitally generate a digital image of said target area using said corrected data.

23. The system as claimed in claim 16, wherein said image generator comprises:

a light source for generating incident light;

a light modulator for modulating said incident light in accordance with said corrected data, thereby obtaining a modulated light; and

an optical processor for optically processing said modulated light, thereby obtaining said image of said target area.

24. The system as claimed in claim 23, wherein said image generator comprises an image sensor for detecting said optical image and generating a digital image of said target area.

25. The system as claimed in claim 20, wherein said raw data correcting module is adapted to:

generate an initial modulation pattern using said raw data, said initial modulation pattern comprising points organized in accordance with an azimuth axis and a range axis, each one of said points being associated with an amplitude value and a phase value;

determine an azimuth shift in accordance with said parameter change; and

translate said points of said initial modulation pattern in accordance with said azimuth shift in order to obtain a corrected modulation pattern.

26. The system as claimed in claim 25, wherein said image generator comprises:

a light source for generating incident light;

a light modulator for modulating said incident light in accordance with said corrected modulation pattern, thereby obtaining a modulated light; and

an optical processor for optically processing said modulated light in order to obtain an optical image of said target area.

27. The system as claimed in claim 26, wherein said image generator comprises an image sensor for detecting said optical image.

28. The system as claimed in claim 17, wherein said parameter change comprises a change of one of a pulse repetition frequency, a range sampling frequency, and a slant range distance.

29. The system as claimed in claim 20, wherein said parameter change comprises a change of one of a squint angle and an eccentricity of a platform orbit.

30. The system as claimed in claim 16, wherein said memory is adapted to store said raw data generated by one of a synthetic aperture radar system, a synthetic aperture sonar system, a synthetic aperture lidar system, a synthetic aperture terahertz system, and a synthetic aperture infrared system.