Magnetic resonance apparatus having an optical fiber with a bragg grating for measuring mechanical deformations

• US 20020008518A1
• Filed: 07/10/2001
• Published: 01/24/2002
• Est. Priority Date: 07/18/2000
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Arz, Winfried, Drobnitzky, Matthias
• Granted Patent: US 6,636,041 B2
• Time in Patent Office: Days
• US Class Current: 324/322
• CPC Class Codes: G01R 33/28 Details of apparatus provided for in groups G01R33/44 - G01R33/64
• CPC Class Codes: G01R 33/56563 caused by a distortion of the main magnetic field B0, e.g. temporal variation of the magnitude or spatial inhomogeneity of B0 G01R33/56509, G01R33/56518, G01R33/56536 take precedence

Abstract

A magnetic resonance apparatus has at least one section of an optical fiber with at least one Bragg grating having a Bragg wavelength. The Bragg grating is arranged with respect to the magnetic resonance apparatus so that at least one deformation of the magnetic resonance apparatus can be acquired.

Claims

1. A magnetic resonance apparatus comprising:

an apparatus component subject to mechanical deformation; and

an optical fiber having a Bragg grating therein with a Bragg wavelength associated therewith, said optical fiber being mounted relative to said apparatus component so that said deformation of said apparatus component alters said Bragg wavelength.

2. A magnetic resonance apparatus as claimed in claim 1 wherein said optical fiber has an optical fiber section in which said Bragg grating is disposed, and wherein said optical fiber section is mechanically rigidly attached to said apparatus component.

3. A magnetic resonance apparatus as claimed in claim 1 wherein said Bragg grating is first Bragg grating with a first Bragg wavelength, and wherein said optical fiber further contains a second Bragg grating having a second Bragg wavelength associated therewith, and wherein said deformation of said apparatus component alters at least one of said first Bragg wavelength and said second Bragg wavelength.

4. A magnetic resonance apparatus as claimed in claim 1 further comprising an operating device connected to said optical fiber for emitting light into said optical fiber.

5. A magnetic resonance apparatus as claimed in claim 4 wherein said operating device comprises a light transmitter which emits light having a prescribable spectral bandwidth.

6. A magnetic resonance apparatus as claimed in claim 5 wherein said light transmitter is selected from the group consisting of tunable laser diodes and light emitting diodes.

7. A magnetic resonance apparatus as claimed in claim 4 wherein said operating device further comprises a light receiver disposed for receiving light that is emitted into said optical fiber and that is reflected from said Bragg grating and for performing a wavelength-selective analysis of said reflected light to measure said deformation of said apparatus component.

8. A magnetic resonance apparatus as claimed in claim 7 wherein said light receiver, in said wavelength-selective analysis, compensates for a temperature variation of said optical fiber.

9. A magnetic resonance apparatus as claimed in claim 7 further comprising:

an actuator disposed relative to said apparatus component for counter-deforming said apparatus component; and

a control circuit connected to said actuator and to said light receiver for operating said actuator, dependent on said measure of said deformation, to counter-deform said apparatus component to counteract said deformation of said apparatus component.

10. A magnetic resonance apparatus as claimed in claim 9 further comprising an operating unit connected to said apparatus component for operating said apparatus component dependent on a variable, with operation of said apparatus component by said operating unit producing said deformation of said apparatus component;

and

said control circuit being connected to said operating unit and being supplied with said variable from said operating unit, and said control circuit controlling said actuator dependent on said measure of said deformation and said variable.

11. A magnetic resonance apparatus as claimed in claim 10 wherein said variable is selected from the group consisting of a command variable, a manipulated variable and a regulating variable.

12. A magnetic resonance apparatus as claimed in claim 9 wherein said actuator is mechanically rigidly connected to said apparatus component, and wherein said control circuit controls said actuator to counteract said deformation of said apparatus component by opposing said deformation of said apparatus component.

13. A magnetic resonance apparatus as claimed in claim 9 wherein said actuator is mechanically rigidly connected to said apparatus component, and wherein said control circuit controls said actuator to counteract said deformation of said apparatus component by opposing transmission of said deformation of said apparatus component.

14. A magnetic resonance apparatus as claimed in claim 9 wherein said actuator comprises a piezo-electric element.

15. A magnetic resonance apparatus as claimed in claim 9 wherein said magnetic resonance apparatus comprises a plurality of components including a gradient coil system, a superconducting basic field magnetic system having a vacuum vessel and a cryoshield, an antenna system, an outer apparatus sheath, and a connector for connecting said outer sheath to a surrounding environment, and wherein said apparatus component is one of said plurality of components.

16. A magnetic resonance apparatus as claimed in claim 15 wherein said optical fiber has an optical fiber section in which said Bragg grating is disposed, and wherein at least one of said optical fiber section and said actuator is integrated into said apparatus component.

17. A magnetic resonance apparatus as claimed in claim 16 wherein said plurality of components are connected to each other at a plurality of connecting points, and wherein said optical fiber has an optical fiber section in which said Bragg grating is disposed, and wherein at least one of said optical fiber section and said actuator is disposed at one of said connecting points.

18. A magnetic resonance apparatus as claimed in claim 9 wherein said magnetic resonance apparatus has an exterior, and wherein said apparatus component comprises a component connecting said exterior to a surrounding environment, and wherein said optical fiber has an optical fiber section in which said Bragg grating is disposed, and wherein at least one of said optical fiber section and said actuator is disposed in said component connecting said exterior to said environment.

19. A magnetic resonance apparatus as claimed in claim 1 wherein said apparatus component is a cast component, and wherein said optical fiber has an optical fiber section in which said Bragg grating is disposed, and wherein said optical fiber section is cast together with said cast component.

20. A magnetic resonance apparatus as claimed in claim 1 wherein said optical fiber has an optical fiber section in which said Bragg grating is disposed, and wherein said apparatus component has a surface, and wherein said optical fiber section is disposed proximate to said surface of said apparatus component.

21. A magnetic resonance apparatus as claimed in claim 1 wherein said apparatus component comprises a hollow-cylindrical gradient coil system.

22. A magnetic resonance apparatus as claimed in claim 21 wherein said gradient coil system has a longitudinal direction, wherein said optical fiber has an optical fiber section in which said Bragg grading is disposed and wherein said optical fiber section is oriented in said longitudinal direction.

23. A magnetic resonance apparatus as claimed in claim 21 wherein said gradient coil system has a circumferential direction, wherein said optical fiber has an optical fiber section in which said Bragg grading is disposed and wherein said optical fiber section is oriented in said circumferential direction.

24. A magnetic resonance apparatus as claimed in claim 21 wherein said gradient coil system has a radial direction, wherein said optical fiber has an optical fiber section in which said Bragg grading is disposed and wherein said optical fiber section is oriented in said radial direction.

25. A magnetic resonance apparatus as claimed in claim 21 wherein said gradient coil system has an outer cylinder surface and wherein said optical fiber has an optical fiber section in which said Bragg grating is disposed, said optical fiber section being disposed on said surface.

26. A magnetic resonance apparatus as claimed in claim 21 wherein said gradient coil system has an inner cylinder surface and wherein said optical fiber has an optical fiber section in which said Bragg grating is disposed, said optical fiber section being disposed on said surface.