Deterministic direct design method for a spherical-aberration-free singlet lens with reduced coma.

It is still challenging to find a spherical-aberration-free singlet lens with well corrected coma due to an undesired and complicated residual high-order coma. In this paper, we present a spherical-aberration-free singlet lens with reduced coma containing high-order coma contribution. This design algorithm is to deduce the front aspherical surface parameters from the back spherical surface using meridional ray tracing to find the proper values of the back focal length and the back spherical radius to reduce the coma. The exemplary lens demonstrates an excellent well-balanced and diffraction-limited performance at the field angle ranging from 0.0° to 2.5° with a working F# equal to 1.65.