We present a new method for the form measurement of optical surfaces using the spatial coherence function, which enables a shearing interferometer in combination with an LED multispot illumination to function as a measurement device. A new evaluation approach connects the measured data with the surface form by inverse raytracing. First measurement results with the inverse evaluation procedures are shown. We present the whole measurement in combination with the evaluation procedure. In addition, the convergence and stability of the implemented optimization task is investigated.