The aberration theory of plane-symmetric grating systems are extended to be applicable to the aberration analysis of refractive plane-symmetric systems. As a result
the aberrations for plane-symmetric reflective and refractive optical systems are expressed in a unified set of formulae. They can be validated by the analytical formulae of ray-tracing spot diagram based on the Fermat’s principle. It is described how to use our wave-aberration coefficients to derive the Seidel aberration in the case of axially symmetric refractive systems. Moreover
the modification of wave and ray aberrations is studied when the entrance pupil is displaced from the optical surface.