A laser guitar??What the hell is he talking about?well there is something like that.Actually it is used to control midi instruments.
The advantage of this is that it can foresee or rather guess what note is going to be played next. The laser detects the pitch of the note being played. So by holding the string on the 20th fret or so increases the pitch adn similarly if you are playing on a lesser fret number than you have a lower pitch.
Basically if you are into recording and you like to get any sound you want this will be amazingly helpful to you.
Recording can be dine directly to your DAW with a sequencer software. It can be used to practise with smartphone apps and also used to play games like Guitar Hero and Rockband.