LOW-TEMPERATURE FORCE MICROSCOPE WITH ALL-FIBER INTERFEROMETER

A low-temperature force microscope has been demonstrated which is suitable for both repulsive and attractive mode (including magnetic) imaging. This instrument uses microfabricated cantilevers and an all-fiber interferometer for remote sensing of cantilever deflection. The all-fiber interferometer is ideal for remote sensing, since the only connection between the microscope and the outside environment is a single optical fiber. This allows all electronic components to operate at room temperature far from the mechanical portion of the microscope. The microscope mechanics are enclosed in a cylindrical vacuum chamber which is inserted into a helium storage Dewar for refrigeration. The sample holder is fitted with either a superconducting magnet capable of 200 Oe or a permanent magnet for higher fields. The instrument has been used successfully for topographic imaging and magnetic force gradient imaging at 5 and 300 K. An appendix to this paper gives practical information for constructing the all-fiber interferometer.