Quasi-absolute testing of aspherics using dual-wavefront diffractive optical elements: some error influences

Interferometric testing of aspherical surfaces with highest accuracy requires the elimination of the systematic aberrations of the interferometer. Over the past years we applied the principle of the three position test for spheres to the asphericity test by using special dual-wavefront diffractive optical elements. In our contribution, we investigate the influence of several possible error sources on the accuracy of the absolute testing procedure. Such possible influences include lithographic structuring errors, design considerations of the diffractive optical element used, and coherent noise. Experimental as well as simulation studies will be presented.