Standard-deviation minimization for calibrating the radii of spheres attached to atomic force microscope cantilevers.

We describe an efficient method for determining the radii of spheres attached to atomic force microscope (AFM) cantilevers by minimizing the square root of the square error for a segment of circular arc cross-sectional data. The approach we present has benefits: (1) The method fits a function, with two fitting parameters, to a number of data points, rather than calculating the radius based on two points of cross-sectional data, (2) a fit is performed in a common spreadsheet application, using a solving feature, and (3) spheres of diameters 2 to 60 μm were measured to an accuracy of 9% and a precision of 4%. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]