Quasi-powers and primary aberrations of thin lenses in contact

This paper introduces a novel framework for analysing the aberrations of thin lenses, based on the concept of surface quasi power. Using these surface variables, remarkably simple expressions have been derived for all primary aberrations of systems of thin lenses in contact. Apart from a constant term, primary aberrations become essentially sums of powers of the new variables. When the emphasis is on qualitative properties rather than on quantitative ones, then even in complex optical systems groups of lenses can be modelled as thin lenses in contact. Especially for spherical aberration, the simplicity of the new formalism helps explaining significant properties of the lens design landscape.