Here are the white light and IR headlights on a M113. The technology and design dates back to at least the 1950s. When you take it apart, it is a standard headlight covered by the IR Lens. But I never did look thru the IR lens to see if it was transluscent at all. However, when it was operating at night, no visible light can be seen coming out by the Mk.I eyeball, unless you have some sort of night vision device, either active IR or image intensification type.