I remember from my optics class years ago that one can make an optical lens out of a set of concentric rings, alternatively transparent and dark. By choosing the diameter and width of said rings, the lenses properties can be tuned, so typically they would be achieved using spatial light modulators (SLM).
Initially I thought I remembered them as Fresnel lenses but then the Wikipedia page does not match that description. They do not seem to be featured on this list of lens designs either.
Does anyone know how they are called and where documentation can be found about them?