Twenty-eight and counting

Abstract

After 28 years from the conception of the pyramid WFS several new kind of devices able to convert wavefront shape into some sort of different illumination on a detector have been conceived. While, suspending momentarily any kind of modesty, I claim credit for being among the few that contributed to show at the time that there could be much more than just a lenslet array I continued -- with alternating successes -- to conceive other types of such devices.