Renormalization of the Buchdahl-Rimmer coefficients of the reduced geometric aberration functions to rms spot size

The renormalization of the Buchdahl-Rimmer coefficients of the reduced geometric aberration functions is carried out so that the optical designer can compare directly the values of different aberrations since the largest numerical value of the aberration coefficients will, after suitable renormalization, represent the most important aberration in the degradation of the image quality. The renormalization of the Buchdahl-Rimmer cofficients is carried out in terms of the radial and sagittal geometric modulation transfer functions at very low spatial frequencies so that these re-normalized coefficients will be of use for the evaluation and optimization of optical, systems with large aberrations, that is for non-diffraction-limited systems.