Magnetic modulation of force sensor for AC detection in an atomic force microscope
US5513518A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 10, 1995 |
| Grant date | May 7, 1996 |
| Priority date | — |
| Expiry date | Mar 10, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S977/951
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In a scanning force microscope a thin film of a magnetic material is applied to one or both surfaces of a force sensing cantilever. The cantilevers are then placed between the poles of an electromagnet and a magnetizing field applied in the direction of the soft axis of the cantilevers. The field is chosen so as to be bigger than the saturation field for the magnetic film. A small electromagnet is placed in the housing of the microscope so as to generate a field normal to the soft axis of the cantilever. The field is generated by an ac voltage and causes a time varying force to be applied to the cantilever. The corresponding modulation of the cantilever position is sensed by reflection of a laser beam into a position sensitive detector. The magnitude and phase of this signal are determined by a synchronous detector. Images of the sample surface are made at constant force gradient by scanning the cantilever over the surface while adjusting the gap between the probe and sample so as to maintain a constant output from the synchronous detector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.