Abstract: Interference measurements obtained by comparison of a same beam (i.e. same nominal polarization, intensity, coherence length and wavelength) striking a same region on a sample at a same angle, but having a different beam wavefront upon intersection with the region are shown to provide images with independent coherent speckle noise patterns. Accordingly a plurality of interference measurements with diverse beam wavefronts can be used to identify or reduce coherent speckle noise. Reduction of the coherent speckle noise can be performed by compounding the aligned images. A change in the beam wavefront may be provided by displacing the sample in the direction of the beam between or during the measurements, when the beam is a focused beam (i.e. converging or diverging).