Night Vision Goggles (NVG) provide an extraordinary capability for the pilot/observer to "look" outside the aircraft at night. This vision allows a pilot to fly closer to terrain and perform safe landings and takeoffs as well as provide covert surveillance. The NVGs are sensitive to infra-red (IR) light which comes from the stars and moon. The IR light reflects off the terrain and is "seen" by the NVG's. 

Cockpit lighting allows a pilot to see his instruments and radios at night. Cockpit lighting, however, emits mostly infra-red light itself because it is usually incandescent. Incandescent lighting emits more than 90% of its energy in the IR range that the NVG are sensitive to. Result, the NVGs are blinded by vast amounts of IR present in the cockpit since they are designed to pick up small amounts of IR at a distance. So, standard lighting is not compatible with using NVGs since they are sensitive to even the dimmest standard cockpit lighting.