US report on what they found "Prior to the discovery of the German developments in this field, the United States had been unsuccessful in converting infra-red to visible light. Investigation has revealed that the Germans not only succeeded in converting infra-red light into visible light but also had been successful in its application for military purposes to a remarkable degree. They had applied this development in perfecting a spotlight which made possible the movement of army vehicles in total darkness without the use of visible illumination."