Laminography system and method with electromagnetically directed multipath radiation source

• US 5,259,012 A
• Filed: 08/30/1990
• Issued: 11/02/1993
• Est. Priority Date: 08/30/1990
• Status: Expired due to Term

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Four Pi Systems Corp. (HP Inc.)
• Inventors: Adams, John A., Baker, Bruce D., Corey, Robert L.
• Primary Examiner(s): Porta, David P.
• Assistant Examiner(s): CHU, KIM KWOK
• Application Number:
  US07/575,342
• Time in Patent Office: 1,160 Days
• Field of Search: 378/21, 378/22, 378/25, 378/99, 378/26, 378/23, 378/137, 378/121, 378/10, 378/143, 378/145, 250/370.1
• US Class Current: 378/21
• CPC Class Codes: A61B 6/027 characterised by the use of a particular data acquisition trajectory, e.g. helical or spiral
• CPC Class Codes: A61B 6/4028 resulting in acquisition of views from substantially different positions, e.g. EBCT
• CPC Class Codes: A61B 6/4476 related to motor-assisted motion of the source unit
• CPC Class Codes: H01J 35/30 by deflection of the cathode ray

Abstract

A tomographic inspection system which enables multiple locations within an object to be imaged without mechanical movement of the object. The object is interposed between a rotating X-ray source and a synchronized rotating detector. A focal plane within the object is imaged onto the detector so that a cross-sectional image of the object is produced. The X-ray source is produced by deflecting an electron beam onto a target anode. The target anode emits X-ray radiation where the electrons are incident upon the target. The electron beam is produced by an electron gun which includes X and Y deflection coils for deflecting the electron beam in the X and Y directions. Deflection voltage signals are applied to the X and Y deflection coils and cause the X-ray source to rotate in a circular trace path. An additional DC voltage applied to the X or Y deflection coil will cause the circular path traced by the X-ray source to shift in the X or Y direction by a distance proportional to the magnitude of the DC voltage. This causes a different field of view, which is displaced in the X or Y direction from the previously imaged region, to be imaged. Changes in the radius of the X-ray source path result in a change in the Z level of the imaged focal plane.

Claims

1. A laminography system comprising:

an X-ray source adapted for emitting X-rays from a moving point, said X-ray source further comprising;

a source of electrons for producing a beam of electrons;

a target anode for converting said beam of electrons into an X-ray source when said beam of electrons impinges upon said target anode;

an electromagnetic deflector for electronically deflecting said beam of electrons onto said target anode along a first predetermined path about a first designated location such that X-rays are emitted from a moving point which follows said first predetermined path about said first designated location;

a planar X-ray detector adapted to move along a predetermined path which is coordinated with said first predetermined path of said X-ray source to produce a laminographic image of a first field of view of an image plane within an object being inspected; and

a control system for regulating and directing said electromagnetic deflector to deflect said beam of electrons onto said target anode along a second predetermined path about a second designated location such that X-rays are emitted from a moving point which follows said second predetermined path about said second designated location, said second predetermined path coordinated with said planar X-ray detector predetermined path to produce a laminographic image of a second field of view of the image plane within the object without altering either the position of the object or said predetermined path of said X-ray detector.

2. A laminography system as defined in claim 1, wherein said X-ray source first predetermined path is circular, and said first designated location is the center of rotation of said circular path.

3. A laminography system as defined in claim 1, wherein said control system comprises a look-up-table (LUT).

4. A laminography system comprising:

an X-ray source which emits X-rays from a moving point, said X-ray source further comprising;

a source of electrons for producing a beam of electrons;

a target anode for converting said beam of electrons into an X-ray source when said beam of electrons impinges upon said target anode;

an electromagnetic deflector for electronically deflecting said beam of electrons onto said target anode along a predetermined first circular path about a center of rotation, said first circular path having a first radius;

an X-ray detector coordinated with said X-ray source so that a first field of view is defined wherein a first cross-section image of an object placed in said first field of view is produced by the detector; and

a control system for regulating and directing said electromagnetic deflector to deflect said beam of electrons onto said target anode to cause said moving point of said X-ray source to rotate in a second circular path about said center of rotation, said second circular path having a second radius, so that a second field of view is defined wherein a second cross-section image of said object placed in said second field of view is produced by the detector, thereby producing images of said object from said first and said second fields of view without altering either the location of said object or said detector.

5. A laminography system as defined in claim 4 wherein said control system comprises a look-up-table (LUT).

6. A method of producing a laminographic image comprising the steps of:

generating a source of X-rays which follows a predetermined path about a designated point, said generating step further comprising the steps of;

producing a beam of electrons;

directing said beam of electrons into a target anode thereby producing said X-rays;

electronically deflecting said beam of electrons to follow said predetermined path about said designated point;

coordinating an X-ray detector with said moving X-ray source so that a field of view is defined in an object plane wherein a cross-sectional image of an object placed in the field of view is produced by the detector;

maintaining the configurations of said X-ray detector and said object; and

electronically shifting the designated point about which said predetermined path of said beam of electrons follows, thus shifting the designated point about which said X-ray source travels, thereby shifting the location of said field of view in said object plane.

7. A method of producing a laminographic image as defined in claim 6, wherein said X-ray source is moved along a circular path, and said designated point is defined as the center of rotation of said circular path.

8. A method of producing a laminographic image comprising the steps of:

generating a source of X-rays which follows a predetermined first circular path about a center of rotation, said first circular path having a first radius, said generating step further comprising the steps of;

producing a beam of electrons;

directing said beam of electrons into a target anode thereby producing said X-rays;

electronically deflecting said beam of electrons to follow said predetermined first circular path about said center of rotation;

coordinating an X-ray detector with said rotating X-ray source so that a field of view is defined in an object plane wherein a cross-sectional image of an object placed in the field of view is produced by the detector;

maintaining the configuration of said X-ray detector and said object; and

electronically changing the radius of rotation of said X-ray source thereby causing said X-ray source to rotate in a second circular path about said center of rotation, said second circular path having a second radius, thereby shifting the location of said field of view.

9. A laminography system comprising:

a moving source of X-rays, said moving source of X-rays further comprising;

a source of electrons for producing a beam of electrons;

a target anode for converting said beam of electrons into an X-ray source when said beam of electrons impinges upon said target anode;

an electromagnetic deflector for electronically deflecting said beam of electrons onto said target anode along a predetermined path such that X-rays are emitted from a moving point which follows said predetermined path;

an X-ray detector having an image area which is coordinated with said moving source of X-rays;

means for supporting an object to be inspected in a stationary position located between said moving source of X-rays and said detector; and

a control system comprising;

a driver for driving said moving source of X-rays along said predetermined path;

a coordinator for coordinating the motion of said moving source of X-rays with said detector in a manner which produces a laminographic image having a field of view in an object plane of the object under inspection; and

a field of view shifter for altering said predetermined path followed by said moving source of X-rays thereby moving the field of view and producing a laminographic image of a different portion of the object without changing the configuration of either the object or the detector.

10. A laminography system comprising:

a source of X-rays adapted for emitting X-rays from a moving point, said source of X-rays further comprising;

a source of electrons for producing a beam of electrons;

a target anode for converting said beam of electrons into an X-ray source when said beam of electrons impinges upon said target anode;

an electromagnetic deflector for electrically deflecting said beam of electrons onto said target anode along a first circular path about a center of rotation, said first circular path having a first radius;

an X-ray detector having an image area which is adapted to move along a predetermined path which is coordinated with said first circular path of said X-ray source to produce a laminographic image of a portion of a first image plane within an object being inspected; and

a control system for regulating and directing said electromagnetic deflector to deflect said beam of electrons onto said target anode to rotate said X-ray source in a second circular path about said center of rotation, said second circular path having a second radius, thereby producing a laminographic image of a portion of a second image plane within the object without altering either the position of the object or the path of the detector image area.

11. A laminography system comprising:

a moving source of X-rays, said moving source of X-rays further comprising;

a source of electrons for producing a beam of electrons;

an electromagnetic deflector for electronically deflecting said beam of electrons;

a target anode for converting said beam of electrons into an X-ray source when said beam of electrons impinges upon said target anode, said target anode having a plurality of concentric rings wherein said deflector deflects said electron beam to a specific concentric ring;

an X-ray detector which is coordinated with said moving source of x-rays to produce a laminographic image of a first portion of an image plane within an object to be inspected when said moving source of X-rays is from a first one of said concentric rings; and

a control system for deflecting said beam of electrons onto said target anode so that a selected circular path, corresponding to a second one of said concentric rings of said target anode, is traced by said moving source of X-rays, thereby producing a laminographic image of a second portion of said image plane within the object without altering the position of the object or the configuration of the detector, the change in position of said image plane from said first portion to said second portion being determined by the selection of said first and second concentric rings of said X-ray target anode, respectively.

12. A laminography system comprising:

a moving source of X-rays, said moving source of X-rays further comprising;

a source of electrons for producing a beam of electrons;

an electromagnetic deflector for electronically deflecting said beam of electrons;

a target anode for converting said beam of electrons into an X-ray source when said beam of electrons impinges upon said target anode, said target anode being formed to have a cylindrical interior surface about a central axis;

an X-ray detector which is coordinated with said moving source of X-rays to produce a laminographic image of a portion of a first image plane within an object to be inspected when said deflector deflects said electron beam to a first location along said central axis; and

a control system for deflecting said beam of electrons onto a second location along said central axis of said cylindrical interior surface of said target anode, thereby producing a laminographic image of a portion of a second image plane within the object without altering the position of the object or the configuration of the detector, the change in position of said laminographic image from said first image plane to said second image plane being determined by the selection of said first and second locations along said central axis of said circular path of said moving source of X-rays.

13. A laminography system comprising:

a moveable source of penetrating radiation, said moveable source further comprising;

a source of electrons for producing a beam of electrons;

a target anode for converting said beam of electrons into an X-ray source when said beam of electrons impinges upon said target anode; and

an electromagnetic steering device for electronically controlling the motion of said source;

an imaging system for producing a cross-sectional image of a cutting plane of an object, said imaging system comprising;

a radiation detector having a variable position image forming region wherein the position of said image forming region is monitored by a position sensor which transmits coordinates corresponding to its position; and

a detector control system which receives said coordinates from said sensor and transmits corresponding signals to said steering device thus causing said motion of said radiation source to be synchronized with said motion of said image forming region; and

a field of view controller, connected to said steering device, for selecting first and second fields of view for said cross-sectional image of a cutting plane of said object, wherein said first field of view is produced when said controller causes said steering device to move said source of penetrating radiation along a first predetermined path having a first reference point and said second field of view is produced when said controller causes said steering device to move said source of penetrating radiation along a second predetermined path having a second reference point.

14. An apparatus as defined in claim 13 wherein said field of view of controller further comprises a position controller for positioning said first and second predetermined path reference points.

15. An apparatus as defined in claim 14 wherein said position controller further comprises an X-Y plane shifter for positioning said first and second predetermined path reference points at different points in an X-Y plane thus producing said first and second fields of view cross-sectional images of a cutting plane of said object at different locations of said X-Y plane.

16. An apparatus as defined in claim 15 wherein said X-Y plane shifter further comprises a deflection device.

17. An apparatus as defined in claim 13 wherein said field of view controller further comprises a path shape controller for shaping said first and second predetermined paths.

18. An apparatus as defined in claim 17 wherein said path shape controller further comprises a path size controller for producing first and second predetermined paths having substantially the same shape and different sizes thus producing said first field of view cross-sectional image of a first cutting plane of said object and said second field of view cross-sectional image of a second cutting plane of said object.

19. An apparatus as defined in claim 18 wherein said path shape controller further comprises a gain device.

20. A laminography system comprising:

a moveable source of penetrating radiation, said moveable source further comprising;

a source of electrons for producing a beam of electrons;

a target anode for converting said beam of electrons into an X-ray source when said beam of electrons impinges upon said target anode; and

an electromagnetic steering device for electronically controlling the motion of said source along a predetermined path;

an imaging system, coordinated with said moveable source of penetrating radiation, for producing a cross-sectional image of a cutting plane of an object located adjacent said moveable source and said imaging system such that radiation from said source passes through said object before reaching said imaging system; and

a field of view controller for producing first and second fields of view of said cross-sectional image of a cutting plane of said object solely by controlling the configuration of said source predetermined path.