In a previous project I used infrared filters to detect a specific band of IR light. Like 850NM filter to catch the light from the 850NM IR Lamps.
Infrared light reflection
It is supposed to bounce the same way that visible light does but because it is undetected by the human eye you may be surprised how strong it is when you use a camera with a filter to detect the light. You may be surprised by where it bounces in an enclosed space... Shiny surfaces will have more reflectivity, white will reflect better than dark surfaces.