A warm body can be detected by thermal imaging equipment from its IR (Infrared) heat signature. It’s a difficult challenge to avoid detection, be it animal or human. Warm blooded.
You may be camouflaged in the best concealment there is, but you may be highly visible to thermal imaging from someone with a IR thermal scope on the ground or maybe a drone flying overhead. Same thing for any warm or hot equipment that you may wish to conceal.
What is Infrared (IR)?
It’s light that’s not visible to the human eye. It’s electromagnetic radiation with longer wavelengths than visible light.
Infrared extends from the red edge of the visible spectrum at 700 nanometers (frequency 430 THz), to 1 millimeter (300 GHz).
Most of the thermal radiation emitted by objects near room temperature is infrared.
Humans actually emit (instead of just reflecting) at IR wavelengths. Our normal body temperature radiates chiefly within the thermal infrared region of (8 – 15 µm) or (0.008 – 0.015 millimeters) – a frequency range of 20–37 THz.
That’s right in the infrared and is detectable by sophisticated modern instrumentation.
Thermal imaging devices can ‘see’ you. They create images based on differences in surface temperature by detecting infrared radiation (heat) that emanates from objects (e.g. your body or that of an animal) and their surrounding environment.
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It is difficult to defeat infrared thermal imaging optics, however there are some techniques that make detection more difficult to detect.
How to Hide Heat Signature from Thermal Imaging
Emergency Thermal Mylar Blanket
A simple method to block IR (with caveats) is an ordinary ‘space blanket’, ’emergency blanket’ or thermal blanket.
They are made of Mylar foil and will block IR imagery.
I recommend these (better than others),
TITAN Two-Sided Mylar Emergency Survival Blankets
TITAN Extra-Thick Emergency Mylar Sleeping Bag
Caveats: The foil will block the IR heat signature behind it. Though there’s a problem… Heat will build up inside and will escape ‘somewhere’ (you have to breathe). Heat will escape from openings or wherever the foil is not tightly wrapped.
This heat will then be visible to IR thermal imaging devices. Concealment for the most part will be temporary without more elaborate techniques to disperse the heat.
One of the most effective methods to block IR is to conceal behind glass. Glass is entirely opaque to thermal imaging.
It is not a practical solution though, due to the obvious impracticality of movement or ‘on-the-go’.
For a quick temporary method of IR concealment, throw a blanket over yourself. A thick woolen blanket will help defeat thermal imaging.
Covering with a layer of insulation, the heat is blocked (or partially blocked) so that it doesn’t radiate. This is only temporary concealment as the heat builds beneath the blanket. It may work long enough to conceal during a quick TI scan or Drone flyover…
Blending in with other heat sources
Concealment by blending in next to other warm objects, like warm stones or thick walls that may still be holding the heat from the day.
The vents in buildings may be out-flowing warm air; a source of heat that can help obscure your own thermal outline.
You get the idea… wherever there is existing natural or man-made heat, you can blend in with that to help conceal your presence to an IR or thermal imager.
Wear an insulated jacket
Insulated pants and a hat. It won’t be 100% but it will help lessen the heat signature. Again, the heat will build and escape through the neck openings and face. You could cover your face with cool mud, which will work temporarily.
It’s all pretty much common sense; reduce, disperse, or cover the sources of heat.
Netting will help somewhat, but the holes throughout the webbing of the net will reveal some of the thermal IR heat.
It will help to disperse the heat or hot spots that may be underneath as the airflow will be somewhat broken up by the webbing.
The heat signature will not be as intense, but spread out more. An example may be to cover a vehicle that has been running with netting. Best to leave some air gap between the material and hot surface (prop it up).
Wear a Ghillie suit
A Ghillie suit will help lessen and disperse your heat signature.
Objects between You and the Sensor
Put trees and/or brush between you and the suspected IR imager. Trees overhead will help break up the infrared signature, especially under a heavy canopy of leaves.
Stationary vs. Movement
A moving heat signature at night is quicker to identify than a stationary one (up to a point).
Continue reading: Avoid Detection By Moving SLOWLY
When you are hiding your heat signature (with a Mylar space blanket or other means), under some conditions your signature may look ‘too cold’ to an IR scan of the area (an extra dark outline, or a ‘black hole’), which may make you detectable.
The problem with most IR cloaking methods, IR clothing or netting designed to block IR, is that it will also block the background IR – creating a black hole of varying degrees. Ideally you would want something that ‘cloaks’ or blends your IR signature such that the background scatter at your location is what the observer sees.
Avoid open spaces and skylines by day or night.
Thermal Imaging does not perform well in falling rain.
Continue reading: 10 Tips To Camouflage – Movements & Evasion
I have updated and re-posted this article from it’s original publish date. It has been a popular ‘hit’ on search engines. There are lots of comments below, some of which you might find informative. Add your own too…