Twenty-eight and counting

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.