Apparatus for measuring magnetic sources

• US 5,437,276 A
• Filed: 07/23/1993
• Issued: 08/01/1995
• Est. Priority Date: 07/24/1992
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Takada, Youichi
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): Casler, Brian L.
• Application Number:
  US08/096,468
• Time in Patent Office: 739 Days
• Field of Search: 128/653.1, 128/731, 324/244, 324/248, 324/249
• US Class Current: 600/409
• CPC Class Codes: G01R 33/0356 with flux feedback
• CPC Class Codes: G01R 33/10 Plotting field distribution ; Measuring field distribution

Abstract

There is provided an apparatus for measuring magnetic sources that exist in an object and produce magnetic fields outside the object. The apparatus comprises an element for detecting the magnetic fields which has a sensing portion placed in proximity with the object and adapted to incorporate an observing plane. The observing plane consists of a plurality of sensing blocks each containing at least three sensing planes on which a magnetic sensor is each mounted. The normal directions of the sensing planes are different from each other. The apparatus further comprises an element for evaluating three-dimensionally the intensities of other magnetic fields at given evaluation positions on the basis of values of the magnetic fields at the detecting element, and an element for obtaining data of the magnetic sources on the basis of the intensities of the other magnetic fields evaluated by the evaluation element.

Claims

1. An apparatus for measuring a magnetic source existing in an object to be examined and producing a magnetic field outside the object, the apparatus comprising:

means for detecting the magnetic field, the detecting means having a sensing portion adapted to be placed in proximity with the object and including an observing plane consisting of a plurality of sensing blocks each containing at least three sensing planes on which a magnetic sensor is mounted, normal directions to the sensing planes being different from each other,

means for evaluating three-dimensionally intensities of the magnetic field at a given plurality of evaluation positions on the observing plane using the magnetic field detected by the detecting means; and

means for obtaining positional information and quantity information of the magnetic source using the intensities of the magnetic field evaluated by the evaluating means.

2. An apparatus according to claim 1, wherein the sensing planes of each of the sensing blocks are coupled at side edges of the sensing planes with each other to form a pyramid-like shape and the plurality of sensing blocks are coupled with each other to form the observing plane facing the object, the observing plane having a two-dimensional uneven shape containing a plurality of apexes made by coupling the side edges of the sensing planes.

3. An apparatus according to claim 2, wherein the sensing planes contained in each of the sensing blocks are three in number.

4. An apparatus according to claim 3, wherein each of the sensing planes is square in shape.

5. An apparatus according to claim 4, wherein the pyramid-like shape is an inverted triangular pyramid-like shape to the object.

6. An apparatus according to claim 2, wherein the sensing planes contained in each of the sensing blocks are four in number.

7. An apparatus according to claim 6, wherein each of the sensing planes is square in shape.

8. An apparatus according to claim 7, wherein the pyramid-like shape is an inverted quadrangular pyramid-like shape.

9. An apparatus according to claim 7, wherein each of the sensing planes is triangular in shape.

10. An apparatus according to claim 9, wherein said pyramid-like shape is a quadrangular pyramid-like shape to the object.

11. An apparatus according to claim 2, wherein the observing plane is formed by one base plate.

12. An apparatus according to claim 11, wherein the magnetic sensor is a pickup coil sensing inductively the magnetic field produced by the current dipoles, the pickup coil being formed on each of the sensing planes.

13. An apparatus according to claim 12, wherein the sensing portion includes a superconducting quantum interference device to receive a signal picked up by the pickup coil, the superconducting quantum interference device forming a magnetometer.

14. An apparatus according to claim 11, wherein the magnetic sensor is a superconducting quantum interference device sensing inductively the magnetic field produced by the current dipoles, and the superconducting quantum interference device is disposed each of the sensing planes.

15. An apparatus according to claim 2, wherein the obtaining means comprises:

means for specifying assumed positions of the current dipoles in a given three-dimensional region of the body,

means for determining a relational expression between each directional component of each of the current dipoles at each of the assumed positions and each directional component of the magnetic field produced at each of the evaluation positions, and

means for calculating each of the directional components of the current dipoles at the assumed positions on the basis of the intensities of the magnetic field evaluated by the evaluating means and the relational expression.

16. An apparatus according to claim 15, wherein the evaluation positions consist of a plurality of intersections of the side edges of the sensing planes.

17. An apparatus according to claim 16, wherein the intersections are the apexes.

18. An apparatus according to claim 16, wherein the evaluating means includes means for evaluating the intensities of the magnetic field at at least two of the intersections using the same magnetic fields detected from the same sensing planes detected by the detecting means.

19. An apparatus according to claim 2, wherein the observing plane is formed by a plurality of base plates piled in the depth direction and separated from each other by a given distance.

20. An apparatus according to claim 19, wherein the magnetic sensors mounted on the sensing planes of the plurality of base plates vary in measurement sensitivity depending on the base plate.

21. An apparatus according to claim 20, wherein the plurality of base plates are two in number.

22. An apparatus according to claim 21, wherein the magnetic sensors are pickup coils sensing inductively the magnetic field produced by the current dipoles, and the pickup coils is disposed on the sensing planes.

23. An apparatus according to claim 22, wherein each of the pickup coils form a receiving area for the magnetic field, the receiving area varying depending upon the base plate.

24. An apparatus according to claim 20, wherein the obtaining means comprises:

means for specifying assumed positions of the current dipoles in a given three dimensional region of the body,

means for determining a relational expression between each directional component of each of the current dipoles at each of the assumed positions and each directional component of the magnetic field produced at each of the evaluation positions, and

means for calculating each of the directional components of the current dipoles at the assumed positions on the basis of the intensities of the magnetic field evaluated by the evaluating means and the relational expression.

25. An apparatus according to claim 24, wherein the specifying means includes means for specifying the assumed positions using every base plate, the determining means includes means for determining the relational expression using every base plate, and the calculating means includes means for calculating each of the directional components of the current dipoles using every base plate.

26. An apparatus according to claim 2, wherein the object has a curved surface and the observing plane is curved in conformity to the curved surface.

27. An apparatus according to claim 2, wherein the magnetic sensor mounted on each of the sensing planes is single in number.

28. An apparatus according to claim 2, wherein the magnetic sensor mounted on each of the sensing planes consists of a plurality of magnetic sensors.

29. An apparatus according to claim 28, wherein the magnetic sensor is two in number.