  We present polynomial force reconstruction from experimental intermodulation
atomic force microscopy (ImAFM) data. We study the tip-surface force during a
slow surface approach and compare the results with amplitude-dependence force
spectroscopy. Based on polynomial force reconstruction we generate
high-resolution surface property maps of polymer blend samples. The polynomial
method is described as a special example of a more general approximataive force
reconstruction, where the aim is to determine model parameters which best
approximate the measured force spectrum. This approximative approach is not
limited to spectral data and we demonstrate how is can adapted to a force
quadrature picture.
