Low-cost atomic force microscope development

Abstract

Although the atomic force microscope (AFM) is already standard equipment for material inspection on the nanoscale, it is very expensive. To reduce the price an optical pickup head (OPH) of a commercial DVD player is used in an AFM to vertically actuate the cantilever and detect its deflection. The cantilever is mounted on the movable lens holder of the OPH. A light weight mechanical structure is implemented to align the cantilever. The investigation shows that the laser beam of the OPH, in combination with the astigmatic method, is able to detect the cantilever deflection with a resolution of 0.3 nm rms at a bandwidth of up to 12.7 kHz. The mechanics of the OPH are modified to increase the stiffness of the z-actuator, which improves the ability to reject ground vibrations. A commercial two-dimensional piezo stage is used for xy-scanning. For verification of the AFM system a 114 nm height calibration grid as well as other samples are recorded.