Nonconfocal differential interferometry sensing scheme for scanning probe microscopy

In this work, we describe a nonconfocal differential interferometer to detect the cantilever vibration for a scanning probe microscope. Capable of focusing the beams on the different height surfaces of a cantilever to adapt the length of commercially available cantilever chips, the proposed two-beam interferometer can maintain the sensitivity by placing a glass slip for an object beam to extend the focal length to the cantilever. An experiment involving a scanning force microscope is performed in static mode operation for applications where topography and magnetic images are presented.