A simple wavefront evaluation method is proposed which employs only one Fourier transform lens, one CCD camera and a digital signal processing procedure. The optical setup is sufficiently simple to be used in numerous types of optical systems. The feasibility of the method is demonstrated in an adaptive confocal microscope which dynamically corrects aberrations. This confocal microscope contains a deformable membrane mirror whose shape is optimized using a genetic algorithm and a wavefront evaluation method. (C) 2003 Elsevier B.V. All rights reserved.