A Novel White Light Interference Based AFM Head

A novel atomic force microscope (AFM) head based on white light interference (WLI) is developed for nanoscale surface measurement. In this head, instead of an optical beam deflection (OBD) technique for AFM probe position, WLI fringes on the surface of the probe cantilever are analyzed for probe position. The probe adjustment mechanism is designed, an algorithm based on wavelet transform and Hilbert transform is presented for accurate zero-order fringe positioning, and a calibration method is developed for the relationship between the position of the interference fringes on the surface of the probe cantilever and the vertical displacement of the probe. By these approaches, advantage of high vertical resolution of WLI is combined with that of high horizontal resolution of atomic force probe for nanometer resolution surface measurement. Experiments have been carried out to verify the feasibility and accuracy of the head for AFM measurement. And compared with a commercial AFM, 3-D measurement results of a standard grating prove that the measurement speed of proposed AFM head is 22% faster.