DLP Interactive Projectors

I can hardly wrap my head around how this device operates.  Basically, in the pen there is a bunch of little mirrors and it is like the mirrors take a hundreds or thousands of pictures in fractions of a second.   It then records the data to the computer or whatever program or software one is using.  The advantage of this is the projector does not need a collaborative board.  It can literally be used anywhere!  You can make anything that you want interactive.