The limitation of collimating ability for aspheric lenses is set forth in this paper. The equations for analyzing the limitation are obtained by ray tracing method. By programming the equations we calculate the limitation as a function of focal length and index respectively.
"The limitation of collimating ability for aspheric lenses", Proc. SPIE 4927, Optical Design and Testing, (20 September 2002); doi: 10.1117/12.471694; https://doi.org/10.1117/12.471694