The depth discrimination in confocal microscopy is based on the digital
analysis of depth response signals obtained by each camera pixel during
measurement. Various signal processing algorithms are used for this
purpose. The accuracy of these algorithms is inter alia restricted by
the axial symmetry of the signals. However, in practice response signals
are rather asymmetrical especially in case of measurement objects with
critical surface structures such as edges or steep flanks. We present a
novel signal processing algorithm based on an exponential function with
a cubic argument to handle asymmetrical and also symmetrical depth
response signals. Results obtained by this algorithm are compared to
those of commonly used signal processing algorithms. It turns out that
the novel algorithm is more robust, more accurate and exhibits a
repeatability of a similar order compared to other algorithms.