Optical design with orthogonal representations of rotationally symmetric and freeform aspheres

We review the motivations and intended bene fits of orthogonalized representations of aspheric shapes and demonstrate unexpected gains for design purposes. Leaving aside improvements in 'design for manufacturability', we show that local optimization within standard design codes can find solutions with better optical performance when orthogonal descriptions are employed. Our examples include rotationally symmetric systems as well as systems with no global axis of symmetry and even a system of freeform surfaces (i.e., with no individual axes of symmetry).