Cheap IR Navigation Trick

[Psychlonic]

Obsidian arrowheads litter the countryside near where I live and a trick I like to use to find them involves finding an open field at night and turning on nightvision goggles. Since obsidian is a form of glass, it reflects the infrared spectrum just as any other glass will (think back to how PIR sensors can't see through glass). The result is that arrowheads practically glow in the dark when viewed with nightvision, making it very simple to find them.

So this got me thinking about how IR glow sticks and rigged beacons can be made to mark locations at night to where only a person with nightvision can see them. This is helpful in marking caches, staged equipment, barrier crossings, etc. The problem is that while the light can't be seen, the object itself can be and probably doesn't belong. If someone runs into an IR strobe beacon or a used glow stick hanging from a tree, there's a chance that could be considered evidence. There's also the off chance someone else with nightvision will spot them.

Glass, on the other hand, isn't quite as suspicious. It still might look fishy in certain locations, but most of the time there's absolutely nothing wrong with glass being somewhere. Especially if you're dealing with empty beer and soda bottles, it might just look as if someone was drinking in the area. Happens all the time, no big deal.

Now while beacons emit huge amounts of light and can be seen easiest - and IR glow sticks also emit light to a degree - glass doesn't. Even though it's bright and reflective, it might be harder to distinguish from other things in the area. The easy solution here is to set your glass in patterns. You might even arrange three bottles into a crude "C" for "cache". You see the bright bottles near the edge of a dark parking lot or in an undeveloped lot and you know that's where you need to return to.


Not something most of you are soon to use, but it's just a minor trick to keep in mind for a rainy day, you know? Maybe someone else can think of another application for the glass' reflective properties I might have overlooked.

[stealththief]

Seems like it could be great for covert beacons or messaging if a code was set up between participants.