Active damping of high speed scanning probe microscope components

• US 8,302,456 B2
• Filed: 02/22/2007
• Issued: 11/06/2012
• Est. Priority Date: 02/23/2006
• Status: Active Grant

• Current Assignee: Oxford Instruments Asylum Research Inc (Oxford Instruments PLC)
• Original Assignee: Asylum Research Corporation (Oxford Instruments PLC)
• Inventors: Proksch, Roger
• Primary Examiner(s): NOLAND, THOMAS
• Application Number:
  US11/678,018
• Publication Number:
  US 20070214864A1
• Time in Patent Office: 2,084 Days
• Field of Search: 73/18.9, 73/17.9, 731/05, 734/30, 850/8, 850 18- 19, 850/33
• US Class Current: 73/1.89
• CPC Class Codes: F16F 7/1011 by electromagnetic means
• CPC Class Codes: G01L 5/0038 applying a pushing force
• CPC Class Codes: G01L 5/0061 Force sensors associated with industrial machines or actuators for the specific machine or actuator involved see relevant class, e.g. F01, F04, F16, B66, E21
• CPC Class Codes: G01Q 10/065 Feedback mechanisms, i.e. wherein the signal for driving the probe is modified by a signal coming from the probe itself
• CPC Class Codes: G01Q 70/04 with compensation for temperature or vibration induced errors

Abstract

A technique for actively damping internal vibrations in a scanning probe microscope is disclosed. The excitation of various mechanical movements, including resonances, in the mechanical assembly of an SPM can adversely effect its performance, especially for high speed applications. An actuator is used to compensate for the movements. The actuator may operate in only the z direction, or may operate in other directions. The actuator(s) may be located at positions of antinodes.

Claims

1. A compensating system, comprising:

a support for a sample which is to be measured by touching;

a sensor, which measures motion of the support and produces an output indicative thereof;

a controller, receiving said output from said sensor, and producing a signal based on said output; and

an actuator, driven by said signal from said controller, in a way that damps said motion of the support based on said signal.

2. A system as in claim 1, wherein said support is a component of an atomic force microscope.

3. A system as in claim 2 wherein said component is part of a constant contact type atomic force microscope.

4. A system as in claim 2, wherein said component is part of a scanning tip atomic force microscope.

5. A system as in claim 1, further comprising a measuring cantilever, which measures said sample by touching said sample which is to be measured.

6. A system as in claim 5, further comprising using said actuator to move in a Z axis direction to measure said sample by maintaining a specific relationship between said cantilever and said sample.

7. A system as in claim 6 wherein said actuator comprises a first actuator part oriented in said Z direction, and a second actuator part oriented opposite to said first actuator part.

8. a system as in claim 7, wherein said first actuator part measures said sample, and said second actuator part actively damps vibrations of structure of the support.

9. a system as in claim 8, further comprising a mass, attached to said second actuator part.

10. a system as in claim 9, wherein said second actuator part controls movement of said mass to actively damp motion of the support structure.

11. A system as in claim 1, wherein said sensor and said actuator are separate structure.

12. A system as in claim 1, wherein said sensor and said actuator are a single device that produces an output signal based on motion thereof, and which can move based on an applied signal.

13. A system as in claim 12, wherein said single device is a piezo stack.

14. A system as in claim 1, wherein said sensor determines positions of specified movements by said support, and said actuator compensates movements at said positions.

15. A system as in claim 14, wherein said positions of specified movements are anti-nodes, and said actuator includes multiple actuator elements, one at each of said antinodes.

16. A system as in claim 1, further comprising a removable holder that holds said sample, and wherein said sensor measures motion on the removable holder.

17. A system as in claim 1, further comprising a mass element, coupled to said actuator.

18. A system as in claim 1, wherein said controller operates to measure an output of said sensor, and determining if there is motion on said output of said sensor, and to carry out no operations when there is motion on the output of said sensor, and to compensate for said motion of said support when there is motion on said sensor.

19. A measurement compensating system, comprising:

a measuring cantilever;

a support for a sample which is to be measured by movement of said cantilever;

a sensor, which measures motion of the support and produces an output indicative thereof;

a controller, receiving said output from said sensor, and producing a compensating signal based on said output;

a first actuator part, coupled to said support, and movable to move said sample relative to said support and relative to said cantilever, said first actuator part oriented in a first direction relative to said support; and

a second actuator part, coupled to said support, and movable to compensate said support for movement carried out by the first actuator part, said second actuator part driven by said compensating signal for said controller, and said second actuator part oriented to move in a second direction relative to said support, where said second direction is an opposite direction to said first direction.

20. A system as in claim 19, wherein said controller produces a compensating signal based on said output only when said output indicates that said support is moving.

21. A system as in claim 19, further comprising using said first actuator part to move in a Z axis direction to measure said sample by maintaining a specific relationship between said cantilever and said sample.

22. A system as in claim 19, wherein said sensor and said actuator are separate structures.

23. A system as in claim 19, wherein said sensor and said actuator are a single device that produces an output signal based on motion thereof, and which can move based on an applied signal.

24. A system as in claim 19, wherein said positions of specified movements are anti-nodes, and said actuator includes multiple actuator elements, one at each of said anti-nodes.

25. A system as in claim 19, further comprising a mass, attached to said second actuator part.

26. A system as in claim 25, wherein said second actuator part controls movement of said mass to actively damp motion of said support structure.

27. A system as in claim 19, wherein said support sensor includes components of an atomic force microscope.