If for example you had 3 diode lasers (red,green,blue) and wanted to make a projector to display images on the wall, these lenses would be perfect. In the old days it used to be that if your fancy lens design worked at 3 wavelengths, then you regarded it as probably handling all other wavelengths well enough, hence were happy. However, perhaps although that thinking was good enough for old style lenses, it is not valid for these funny new kinds of lenses (?). I do not know since I don't really understand how these work. Perhaps somebody can explain it to me. It seems to be a very cool idea, but exactly how does it work, how could you design your own, what design would be "optimal" (whatever that should mean), what happens at other wavelengths, and how expensive to manufacture... all these things are unclear to me.