Development of the Optical Feedback System of an Atomic Force Microscope

Abstract

A low-cost atomic force microscope (AFM) is under development at Houghton College. Once operating, the AFM will be used to characterize the surface topography of thin metal films, providing image resolution on the order of nanometers. The AFM will be equipped with a modified “Johnny Walker” sample mount to allow for a controlled approach of the sample to the cantilever tip. An optical laser system will be used to image the sample. The beam footprint of a laser reflected off a cantilever oscillating at its resonant frequency will be measured on a Conex PSD9 position sensing detector. A feedback loop written in LabVIEW will control the distance between the cantilever tip and the sample. In order to minimize vibrations, an eddy current and spring dampening system will be implemented.