$645 US is a lot of money!  It looks like it has been used primarily with male pattern baldness.  The laser energy, I would assume stimulates the hair follicle.  If a person was not suffering from hair loss, I doubt the lasercomb would provide any noticible difference. 

It can't have any impact on hair that already exists, since it is not living cells.

Here is a link for more information HairMax Lasercomb.