Common-path interferometer with diffractive lens

We introduce a novel common-path interferometric measurement setup for optical quality testing. The setup is based on an optimized diffractive lens which produces two diffraction orders with equal efficiency and thus forms two interfering beams without any beam splitting or mirror alignments. The fabrication steps of the diffractive element are presented and the testing of the setup with injection molded millimeter scale lenses is briefly discussed. (c) 2006 Optical Society of America.