Figure 20 - This infrared illuminator converts white light into infrared light
Since many materials can be used to pass only infrared light while blocking out most of the visible light, a simple illuminator can be made to convert a standard flashlight into a medium power night vision illuminator. The flashlights shown in Figure 20 both have filters placed over the lenses that only pass infrared light and block out all of the visible light from the incandescent light bulb. Materials such as floppy disk surfaces, 35mm film, and even tinted glass bottles can be made into infrared pass filters. By using a powerful white light source, a fairly intense source of infrared radiation can be made that will form the basis for many night vision security projects.
Figure 21 - A long range night vision system using a laser and optical magnification
Lasers that output infrared radiation can also be used as an illumination source. Lasers are exceptionally effective at sending light over long distances, and infrared lasers operate exactly the same way as visible light lasers. The rig shown in Figure 20 uses a powerful 250 milliwatt infrared laser with a beam spreader to cast an intense infrared beam several hundred feet away so that a camera focused through an optical magnification system can view the scene in complete darkness. This ultra covert night vision system is able to view a distant scene as though it was lit by a high power flood light, yet the only limitation is the optical magnification power of the camera lens.
The solutions to your night vision applications are almost infinite in number, so with a little creativity and a good supply of junk, you can hack together your own stealthy spy gear.