Scanning tunneling microscope (STM) in which the surface of a sample is investigated by change of the tunneling current between a tip of the needle and a substrate. The feedback system moves the needle upwards and downwards keeping the value of the current unchangeable.

Fiber optic atomic force microscope (FOAFM) in which the displacements of the sensitive cantilever are detected by changes of the interferometer "working point" position (i.e. mean separation between interferometer mirrors).

Due to presence of the feedback in FOAFM the optical fiber and needle moves together up and down tracking the profile of the surface. This approach allows better linearity and wider dynamic range to be achieved.

FOAFM of resonance type (tapping mode) in which the atomic action on the needle are detected by the change of the cantilever resonance frequency. The oscillation of cantilever is detected with the aid of fiber optic interferometer Fabry-Perot.

Fiber optic interferometer Fabry-Perot can be used directly (without cantilever) for investigation of the reflecting surfaces. There is a feedback system which moves the fiber up and down tracking the profile of the surface.

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