Optical aberrations described by an alternative series expansion

Aberrations of optical systems are usually analyzed by decomposing the wavefront aberration at a pupil into a series of terms. The Seidel and Zernike series are two common examples, each with its own strengths and weaknesses. A new aberration series is proposed that combines some of the strengths of each. The new series is consistent with the traditional system of aberration types but enables the straightforward characterization and comparison of different optical systems, independent of pupil size or shape. Expressions for the conversion between the new and common aberration series are given, and the physical interpretations of the different aberrations are discussed.