Imaging system and method

• US 8,139,932 B2
• Filed: 12/14/2008
• Issued: 03/20/2012
• Est. Priority Date: 01/01/2008
• Status: Expired due to Fees

• Current Assignee: Israel Aerospace Industries Limited (Government of Israel)
• Original Assignee: Israel Aerospace Industries Limited (Government of Israel)
• Inventors: Zubalsky, Izhack, Altshuler, Yair
• Primary Examiner(s): FULLER, RODNEY EVAN
• Application Number:
  US12/811,017
• Publication Number:
  US 20100310242A1
• Time in Patent Office: 1,192 Days
• Field of Search: 396/12, 348/144
• US Class Current: 396/12
• CPC Class Codes: F41G 7/2213 maintaining the axis of an orientable seeking head pointed at the target, e.g. target seeking gyro
• CPC Class Codes: F41G 7/2253 Passive homing systems, i.e. comprising a receiver and do not requiring an active illumination of the target
• CPC Class Codes: F41G 7/2293 using electromagnetic waves other than radio waves
• CPC Class Codes: G02B 5/003 Light absorbing elements
• CPC Class Codes: G03B 15/006 Apparatus mounted on flying objects
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 23/58 Means for changing the camera field of view without moving the camera body, e.g. nutating or panning of optics or image sensors
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

An optical imaging system is provided for an airborne platform or the like, including an image acquisition unit having an optical axis and configured for providing images in a direction along said axis, the image acquisition unit being mounted to a pointing mechanism configured for selectively pointing said optical axis in a desired direction. The system also has an optical shield configured for shielding said image acquisition unit from receiving undesired electromagnetic radiation from at least one direction different from said desired direction.

Claims

1. An optical imaging system for an air vehicle, comprising an image acquisition unit, a pointing mechanism and an optical shield, said image acquisition unit having an optical axis and configured for providing images in a direction along said axis, said image acquisition unit being mounted to said pointing mechanism, said pointing mechanism being configured for selectively pointing said optical axis in a desired direction, and said optical shield being mounted to said image acquisition system and configured for shielding said image acquisition unit from receiving undesired electromagnetic radiation from at least one direction inclined at an angle not less than a shielding angle to the optical axis, wherein said optical shield is configured for avoiding significantly reducing the overall stiffness of said image acquisition unit when mounted thereto.

2. System according to claim 1, wherein said shield comprises a plurality of cells, each cell having a central axis thereof substantially parallel to said optical axis, and wherein each said cell has an aperture to length ratio not less than that corresponding to said shielding angle.

3. System according to claim 2, wherein said cells are hexagonal cells in honeycomb arrangement.

4. System according to claim 2, wherein said cells are of substantially the same size and shape one to another.

5. System according to claim 2, wherein said cells are made from, or comprise a coating made from, a material that is substantially not reflective, at least with respect to said undesired electromagnetic radiation.

6. System according to claim 2, further comprising an optical magnification unit optically located between said optical shield and said image acquisition unit.

7. System according to claim 6, wherein said optical magnification system comprises a first mirror configured for focusing incident electromagnetic radiation thereon that is parallel to the optical axis towards a second mirror that is configured for directing and focusing the re-directed electromagnetic radiation to an electromagnetic radiation sensitive target of said image acquisition unit.

8. System according to claim 1, wherein said system has a stiffness sufficient to minimize adverse effects of resonant frequencies that may be induced thereon in operation of the system.

9. System according to claim 1, wherein said pointing mechanism comprises a base adapted for mounting the system to the airborne platform or the like, a bracket for mounting said image acquisition unit thereto, and a suitable pan and tilt mechanism for enabling the bracket to be positioned in any desired orientation with respect to said base.

10. System according to claim 9, wherein said pan and tilt mechanism comprises a pan gimbal and a tilt gimbal for enabling the optical axis to be pointed along any desired azimuth and elevation within a predetermined field of regard.

11. System according to claim 10, wherein said pan and tilt mechanism is a stabilized pan and tilt mechanism.

12. System according to claim 1, wherein said image acquisition unit is configured for obtaining images in at least the infra-red spectrum.

13. System according to claim 1, further comprising an aerodynamically contoured cover configured for enclosing said system and for being substantially transparent to a range of wavelengths to be detected by said image acquisition unit.

14. System according to claim 1, wherein said system is adapted for pointing said optical system along a line of sight that is angularly displaced from a source of said undesired electromagnetic radiation such that said optical shield shields said image acquisition unit from receiving said undesired electromagnetic radiation originating from said source.

15. System according to claim 14, wherein said source is any one of the sun, moon or an array of floodlights, and said system is operatively connected to a suitable detector that is configured for determining the location of said source relative to said system.

16. System according to claim 1, further comprising a pod onto which said system is mounted, said pod being configured for being mounted onto the air vehicle.

17. An air vehicle comprising a system as defined in claim 1.

18. Air vehicle according to claim 17, wherein said air vehicle is a UAV.

19. An optical imaging system for an air vehicle, comprising an image acquisition unit, a pointing mechanism and an optical shield, said image acquisition unit having an optical axis and configured for providing images in a direction along said axis, said image acquisition unit being mounted to said pointing mechanism, said pointing mechanism being configured for selectively pointing said optical axis in a desired direction, and said optical shield being mounted to said image acquisition system and configured for shielding said image acquisition unit from receiving undesired electromagnetic radiation from at least one direction inclined at an angle not less than a shielding angle to the optical axis, wherein said optical shield is configured for avoiding significantly reducing the overall stiffness of said image acquisition unit when mounted thereto, and wherein said optical shield is a relatively rigid component, having a weight and an inertia that are low relative to a weight and an inertia, respectively, of said image acquisition unit.

20. An optical imaging system for an air vehicle, comprising an image acquisition unit, a pointing mechanism and an optical shield, said image acquisition unit having an optical axis and configured for providing images in a direction along said axis, said image acquisition unit being mounted to said pointing mechanism, said pointing mechanism being configured for selectively pointing said optical axis in a desired direction, and said optical shield being mounted to said image acquisition system and configured for shielding said image acquisition unit from receiving undesired electromagnetic radiation from at least one direction inclined at an angle not less than a shielding angle to the optical axis, wherein said optical shield is configured for avoiding significantly reducing the overall stiffness of said image acquisition unit when mounted thereto, wherein said optical shield is configured for being deployed between a retracted configuration, in which said optical shield has a compact retracted volume, and a deployed configuration, in which said optical shield has an extended volume having an aperture having an aperture dimension and length having a length dimension, wherein an angle corresponding to a ratio of said aperture dimension to said length dimension is not less than said shielding angle, wherein said image acquisition unit is configured for providing images via said aperture.

21. An optical imaging system for an airborne platform or the like, comprising an image acquisition unit, a pointing mechanism and an optical shield, said image acquisition unit having an optical axis and configured for providing images in a direction along said axis, said image acquisition unit being mounted to said pointing mechanism, said pointing mechanism being configured for selectively pointing said optical axis in a desired direction, and said optical shield being mounted to said image acquisition system and configured for shielding said image acquisition unit from receiving undesired electromagnetic radiation from at least one direction substantially different from said desired direction, said image acquisition unit having a stiffness characteristic, wherein said optical shield is configured for avoiding significantly affecting said stiffness characteristic of said image acquisition unit.