Comparison of two fit algorithms to find the maximum of a simulated confocal intensity curve

A model of a confocal microscope has been developed and tested. The model uses the Boundary Element Method (BEM) to solve the Maxwell equations numerically for the interaction of the light with the object under test. For this part of the model the software SpeckleSim, developed and provided by the Institute of Technical Optics of the University of Stuttgart, is used. The imaging process of the microscope is realized with an implementation based on Fourier optics. With this model a step structure is simulated. To determine the height of the surface, the maximum of the intensity curve for each lateral (x-) position must be determined. The maximum can be located using different fit algorithms for this intensity curve. In this paper two different fit algorithms, the Gaussian function and the third degree polynomial, are analyzed and compared.