Actually, to clarify, a human goal judge turns on a red light when he believes the puck has crossed the line in its entirety. EVERY goal is subject to video review in the NHL office in Toronto. The league office has direct communication with the rink to communicate any findings to the lead referee.
FIFA and various league officials have DISCUSSED the idea of putting a GPS chip in each ball so that its precise location with relation to the goal line may be determined and reviewed.
There is no such technology in the NHL.