Measuring Optical Null Lens Aberrations

NASA Goddard Space Flight Center has developed a verification method to qualify null lenses used in the precision fabrication and testing of an aspheric optic. It uses image-based wavefront sensing to verify that the null optic has been manufactured correctly and integrated correctly into the test setup. The independent characterization of the null optic prior to the aspheric figure measurement reduces uncertainties in the metrology setup and improves the accuracy in the measurement of the absolute figure of the aspheric optic.