Sinc² fitting for height extraction in confocal scanning

The essential step in determination of height in confocal microscopy is localization of the axial peak positions. A sinc²-fitting algorithm was developed to achieve a reliable and theoretically accurate method for height extraction in surface topography measurements. We demonstrate that the sinc² model closely matches the rigorously calculated axial response for some typical cases, such as low- or high-aperture focusing when scanning a planar object. Compared with the existing methods, such as polynomial fitting and Gaussian fitting, sinc² fitting can be used to easily determine the initial values of the fitted parameters. In addition, the method is computationally efficient and theoretically rigorous.