Actually, I can do it in 5 minutes, which means I have time to do it twice.

First I will describe the Hartmann-Shack method using the language of ray optics and then I'll do it again using the language of wave optics.

That way, if anyone got here late, or didn't understand the first time around, they'll have a second chance!

At the end I'll briefly mention some of the limitations of the technique, which also represents an opportunity for future development .