Method and system for fast microscanning

• US 5,774,179 A
• Filed: 11/30/1995
• Issued: 06/30/1998
• Est. Priority Date: 12/28/1994
• Status: Expired due to Fees

• Current Assignee: Her Majesty The Queen In Right of Canada As Represented By The Minister of National Defence
• Original Assignee: Her Majesty The Queen In Right of Canada As Represented By The Minister of National Defence
• Inventors: Chevrette, Paul, Fortin, Jean
• Primary Examiner(s): GARBER, WENDY RAE
• Application Number:
  US08/565,347
• Time in Patent Office: 943 Days
• Field of Search: 346/218, 346/219, 346/335, 346/340, 346/208, 359/813, 359/814
• US Class Current: 348/218.1
• CPC Class Codes: G02B 13/14 for use with infrared or ultraviolet radiation G02B13/008, G02B13/16 take precedence
• CPC Class Codes: G02B 26/0875 by means of one or more refracting elements
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G06T 3/40 Scaling of whole images or parts thereof, e.g. expanding or contracting
• CPC Class Codes: H04N 23/20 for generating image signals from infrared radiation only
• CPC Class Codes: H04N 25/48 Increasing resolution by shifting the sensor relative to the scene
• 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 imaging system for implementation of a microscan includes an array of sensing elements that define an image plane. A movable lensing system is adapted to focus an image on the image plane. Piezoelectric positioners are provided to move the lensing system a predetermined amount and on a predetermined plane parallel to the image plane so that the image focused by the lensing system on the array of sensing elements is displaced on the image plane by the movement of the lensing system. As the lens is moved by the positioners and thus the optical axis of the lens, the image passing through the lens is also moved on the image plane. Moving the lens back and forth or in a predetermined pattern provides dithering of the image so that microscanning can be employed.

Claims

1. A microscanning imaging system for inducing a predetermined amount of dither so as to capture image data at sensing elements when a lensing system is moved by a predetermined distance, comprising:

an array of sensing elements defining an image plane;

a lensing system adapted to focus an image on the image plane; and

,

means coupled to the lensing system for moving the lensing system a same predetermined amount, a plurality of times, and on a predetermined plane parallel to the image plane so that the image focused by the lensing system on the array of sensing elements is displaced on the image plane by a same predetermined distance by the movement of the lensing system to predetermined locations for scanning an image and for providing an image at a plurality of different detector locations; and

, means adapted to capture an image at each said location.

2. A microscanning imaging system as defined in claim 1, wherein the image focused by the lensing system on the array of sensing elements is displaced the predetermined amount on the image plane by movement of the lensing system on the predetermined plane, parallel to the image plane.

3. A microscanning imaging system as defined in claim 2, wherein the predetermined plane is orthogonal to an optical axis of the lensing system.

4. A microscanning imaging system as defined in claim 3, wherein the means coupled to the lensing system for moving the lensing system comprises a piezoelectric device.

5. A microscanning imaging system as defined in claim 3 wherein the lensing system includes:

a lens;

a lens holder for securely holding the lens; and

wherein the imaging system includes

a frame for mounting the lens and lens holder within; and

,

flexible mounting means for coupling the lens holder to the frame to allow the lens and lens holder to be movably held within the frame.

6. A microscanning imaging system as defined in claim 5, wherein the means for moving the lens and the lens holder within the frame, includes a piezoelectric device.

7. A microscanning imaging system as defined in claim 6, wherein the flexible mounting means includes a spring.

8. A method of microscanning an image on an image plane having a plurality of sensing elements, the method comprising the steps of:

a) focusing the image on the plurality of the sensing elements on the image plane through at least a focusing lens of a lensing system;

b) detecting the image focused on the image plane; and

c) after said detecting step is completed, displacing at least a lens of the lensing system parallel to the image plane and orthogonal to the optical axis of said lens to displace the image on the plurality of sensing elements on the image plane in the absence of detecting the image focused on the image plane defined in step (b).

9. A method as defined in claim 8, wherein steps (a) to (c) are repeated sequentially a plurality of times, and wherein the lens is displaced along the same predetermined path after steps (a) to (c) are performed a plurality of times, each displacement performed in step (c) being a distance less than a sensing element'"'"'s pitch.

10. A method as defined in claim 9, comprising the step of obtaining a single microscanned image from a first plurality of images detected after sequentially performing steps (a) to (c) said first plurality of times, comprising the step of interlacing said first plurality of images.

11. A microscanning imaging system comprising:

an array of sensing elements defining an image plane each of the sensing elements having a pitch p;

a lensing system including at least one lens adapted to focus an image on the image plane; and

, means coupled to at least a movable lens of the lensing system for moving at least the movable lens a predetermined amount and on a predetermined plane parallel to the image plane so that the image focused by the lensing system on the array of sensing elements is displaced on the image plane less than the pitch p by the movement of the at least movable lens, and means for interlacing a plurality of sequential images captured by the sensing elements to form a single image of improved resolution.

12. An imaging system as defined in claim 11 wherein the lensing system includes a plurality of lenses coupled together for focusing the image on the image plane, and wherein the plurality of focusing lenses includes the at least movable lens.

13. An imaging system as defined in claim 12 wherein the lensing system includes at least two movable lenses, each of the at least two moveable lenses being movable in different directions along a plane orthogonal to the optical axis of that lens and parallel to the image plane.

14. An imaging system as defined in claim 11, wherein the means coupled to at least a movable lens of the lensing system for moving at least the movable lens includes a piezoelectric transducer.

15. An imaging system as defined in claim 12, wherein the means coupled to at least a movable lens of the lensing system for moving at least the movable lens includes a plurality of piezoelectric transducers.

16. An imaging system as defined in claim 11 having means for flexibly mounting the at least movable lens to a stationary frame.

17. An imaging system as defined in claim 16, wherein the means for moving the at least movable lens includes means for controllably moving the at least movable lens relative to the stationary frame.

18. An imaging system as defined in claim 17, wherein the lensing system includes a telescope having a plurality of lenses.

19. An imaging system as defined in claim 18 wherein at least two lenses of the lensing system are movable, and wherein one of said movable lenses includes the at least one lens adapted to focus the image on the image plane and wherein the other of the two movable lenses includes a lens of the telescope.

20. An imaging system as defined in claim 19, wherein the at least two movable lenses are movable along different orthogonal axes.

21. An imaging system as defined in claim 16, wherein the means for flexibly mounting the at least movable lens to the stationary frame includes at least two springs for normally maintaining the lens in a predetermined position and location in the absence of applied force, each of the springs for allowing movement of the at least moveable lens along two orthogonal axis in the presence of an applied force;

and, at least two elongate laterally flexible joints, each elongate laterally flexible joint for forcing the at least moveable lens to move along an axis corresponding to the longitudinal axis of the respective elongate joint, one joint being laterally flexed when a force is applied to the other joint along its longitudinal axis.