Scanning measurement of aspheres

•We show systematic errors from CGH misalignment in asphere measurement.•New proposed setup based on ellipse, laser interferometer and scanning mirrors.•Demonstration of setup control mechanism.•Results show that topography measurements are possible.

The measurement of aspheres today is often done using computer generated holograms with interferometry. We show that this method holds some significant systematic errors caused by imperfect adjustment of the optical components. This gives rise to the question if a measurement is possible without utilization of computer generated holograms. Therefore we propose a new elliptical setup using a laser interferometer and a set of scanning mirrors. Our work shows that this setup is capable of form measurement for individual aspheres but still poses some adjustment challenges.