One of the survivalist concerns, about the emergence of new technologies and their availability to the general public, is thermal imaging systems, which make it easy to spot human targets in complete darkness. And by extension, any “warm-blooded” animal in the perimeter.
Survive Chaos has therefore decided to answer it, and to clarify a topic usually confidential, or at least on which it is difficult to find reliable information, by offering a quick study of the principles of operation of thermal imagers, and especially ways to escape them … As their name suggests, thermal imaging systems can highlight the heat radiation released by humans, animals, even objects, and materials in a specific environment. This principle is called Thermography, which is based on Infrared (IR) spectrum analysis.
- The most “simple” portable systems are called thermal imagers, or thermal visors when mounted on a weapon. These instruments do not directly measure the temperatures of the different targets in their field, but merely display the temperature differences of these targets according to a scale of colors or light intensities.
- A thermal imager offers somehow instantaneous reading of the infrared spectrum. The photos below will give you a good idea of the principle (Wikipedia source).
- Note that these two images were obtained with sophisticated measuring devices (probably thermal imaging cameras). Affordable “cheap” thermal imagers for the wealthy survivalist such as the Fair Scout models and others give no record of temperatures or even colors. The deviations are expressed in black and white, and the target targets appear on the contrary; the hottest parts are the most explicit and vice versa.
- Any hot body can be detected by IR emitted using a thermal imager, and such equipment represents a real challenge for anyone or anything wishing to go unnoticed. You may have the best camouflage, but you will be quite visible to anyone with an infrared telescope, or the camera of a drone flying over your head.
- And that would be good for any equipment you want to hide. Or a weapon that would come to shoot …
- What is infrared? It is, in a way, a light invisible to the human eye; Electromagnetic radiation with a longer wavelength than visible light, especially in the red part of the spectrum. If these lengths could be measured, they would range from 0.00074 to 0.3 mm. A human body at average temperature irradiates precisely at a wavelength between these two lengths, directly in the infrared!
- In order not to unnecessarily prolong the suspense, let’s say the truth right away: It is tough, if not impossible, to escape the thermal detection. However, some techniques can help make it more difficult, and it is the purpose of this article to deliver them to you.
- The first of these techniques and one of the most effective is to hide behind a glass surface. The glass is opaque to thermography. Despite this, it is not a very practical solution, given the apparent impossibility to walk in a glass cage or build a cabin made of such material from floor to ceiling.
Another method for blocking IRs, simple and effective, can be provided by a silver cover (survival blanket), or a Mylar sheet. The problem with such devices is that no matter what body or material you want to hide below, its heat will increase to an unbearable temperature, or escape to any place that will then be visible to infrared imaging. In this case, such dissimulation will be temporary unless a particular system is developed, which makes it possible to disperse the thermal signature.
A quick way to hide temporarily is to cover yourself with a blanket simply, even a poncho, a tarpaulin, or an unfolded down, as is usually available on field trips. A thick wool blanket, for example, will help “beat” an image or thermal finder. It is covered with an insulating layer so that the heat is blocked (or partially blocked) and does not radiate outside. But again, it is only temporary concealment, insofar as the temperature will gradually increase under the cover until eventually escape. However, such dissimulation may be sufficient in the case of a purely passive defense (that is to say without movements), during a rapid perimeter control made by an enemy who would be equipped with a thermal system,
- Another method of partially hiding infrared would be to be near another hot object such as stones or a thick wall that may have kept the heat accumulated during the day.
- Similarly, ventilation of a building blowing hot air could be a source of heat likely to obscure the thermal signature of a human body. You now have the principle, you to adapt when the time comes with the equipment you have. No matter where a natural or artificial source of heat might be, you could then “mix” it to hide your presence from an enemy with a thermal imaging system.
The myth of clothes and anti thermic suits
- Thick clothing, such as a padded smock jacket, insulated pants, and a hat can help reduce the thermal signature, but can not eliminate it. However, it must be understood that the heat will accumulate inside and evacuate through the openings, including the neck and face, not to mention the hands if they are not covered. To fight against this, we could then cover his face with a scarf or a wet cloth, which would also work temporarily. All this comes from common sense: reduce, disperse, or cover sources of heat.
- A camouflage net could also help, except that the holes would inevitably escape some of the thermal signatures. A net, however, would help disperse the heat beneath, as the airflow would be “broken” somewhere by the mesh, and diffuse that from the hottest parts, which would always be better than nothing. One could apply this principle to cover with a broad camouflage net a vehicle turning, or even wear a Ghillie as snipers do. As such, you will understand that it is not only for a visual camouflage that professional snipers wear this kind of outfit …
- You can also put obstacles between you and a supposed thermal imager, such as trees or bushes. The ridge of the trees will help disperse the infrared signature, especially if the trees are covered with a thick volume of leaves.
- In summary, a simple film allows hiding everything as long as it is not warmed by what is behind. This is where, ironically, an infrared camera will be unable to observe what everyone could see through a bay window, the glass does indeed not let pass the infrared radiative.
- What about the supposed anti-thermal combinations? Do they exist? The answer is no. There is nothing specific. Imagine for a second, it would take a perfectly tight combination, so as not to let slip any heat – cellofrais mummy type – and more air-conditioned so that the outer film does not heat! Apart from the pressurized combinations of cosmonauts, I do not see what could fulfill such a function …
- If one could consider hiding temporarily in a fully waterproof suit – the neoprene or cloth diving suit style – while remaining still, I let you imagine the result of some kind of sustained physical activity in such equipment. The temperature rise would be such that your blood would boil, literally, and your brain would be irretrievably destroyed to leave you in a state of vegetable, and this in the best case. If any good survivalist knows what hypothermia is, you should know that there is also its opposite, namely hyperthermia and that its consequences are just as dramatic.
Unless it’s really cold outside, but in any case, the combination will likely heat up gradually by the heat of the moving body, making it visible to the thermal imager. As you can see, the problem is not simple at all!
- It is, therefore, useless for you to look for tricks to make yourself such a combination (for example, with Mylar sheets or plastic), you would most likely leave your skin there. What exists on the market, and that some may have taken for anti thermic combinations, are pieces of special cloth covered with silver leaves, and sold as such. We can find bonnets, balaclavas, and other models, the largest of which looks like a Niqab, this awful accouterment worn by women bearded (see photo below).
- An American company has specialized in the manufacture of these utensils. To give you an idea, their anti thermic “Niqab” costs 2500 dollars. What to cool certainly,
- Also, and as you now know, this equipment is of limited use since all the heat that could not find an outlet through the protected parts, would drift irremediably to unprotected ones, which would inevitably lead to being spotted. One can, therefore, possibly consider them for protection against drones, in the case of stealth tracking performed from above. But for such protection, it is useless to pay the price like this!
- It must always be kept in mind that a moving thermal signature (in motion) is more easily identifiable by night than a static signature.
- On the other hand, when you try to hide your presence (with a blanket or aluminum foil), it is possible, under certain conditions, that your signature seems too “cold” during an IR control. Which, it must be admitted, would be a shame! This would mean that things around would be warmer, which would make you look on the Imager’s screen as a suspicious “black hole.” This is something to think about, as well. Of course, it is probably better than the opposite, at least if you are in front of a not very experienced observer. Keep in mind that the goal is to mix with the thermal signature of its immediate environment.
- Avoid open spaces and skylines, day and night. These are apparent principles of camouflage that prevail in all cases, including and especially those where we are not supposed to observe us with thermal detection equipment.
- On the other hand, it must be remembered that thermal imaging works much worse in the rain, or when it snows. This kind of weather condition is therefore particularly favorable, attacking an objective that can be defended by IR detectors. Similarly, when it is sunny, or on the contrary in the icy wind. In this case, we will take care to attack with the headwind, as far as possible. The air coming from the front will significantly help to diffuse the thermal signature, or even to suppress it if it is cold enough and that one progresses very slowly.
- From the observer’s point of view, it should be known that the best conditions for effective thermal detection are before sunrise, between -10 ° C and 10 ° C outside and 20 ° C in the building (10 ° C d are ideal), in dry weather and with little wind.
- If it is relatively easy to protect yourself when you are in a static position, the problem becomes much more difficult when you have to move …
- Some solutions “bastards” run on the net, including that, for example, that would shelter by crawling behind an umbrella. Although not stupid in the absolute, this solution has two significant disadvantages: 1. By the usual shape and size of an umbrella, we will inevitably reveal a part of the body at one time or another and 2. An umbrella also hides the view of the one behind, and we can not see where we are going.
- A better solution, if one had to storm an objective protected by observers equipped with thermal imagers, would be to build a sort of rectangular screen from a reliable and transparent plastic sheet, curved in a semicircle – or at least very enveloping – and a height of at least 1 meter. It would then move this screen in front of you while crawling, as and when we advance. Or, if you wanted to stay standing, move forward with a shield the same size as a door …
- But even in this case, an experienced observer with advanced equipment could probably detect a “moving rectangle” darker than the background, which would move in its direction. It would be easy for him to deduce that someone is trying to fool him.
- On the attacking side, the effectiveness of such a trick would depend above all on the level of equipment of the enemy. If the latter is a “simple” survivalist with essential thermal equipment, then it is possible that the deception can work. At least during the movement, because once arrived at the fence, the problem would arise when maneuvering the cutting pliers …
- Protection by appropriate clothing, as we mentioned above, would be in the case of an insufficient displacement.
- The screen solution, the only viable one, is very impractical to implement, and you will have understood that it is particularly difficult, if not impossible, to guard against the detection of thermal imaging equipment. These systems are quite formidable, and that is why, in our file n ° 6 devoted to Night Survival Techniques, we advised survivalists who want to equip themselves and make the difference in a context of chaos.
- The only flaw in thermography, and contrary to a well-established legend is that it does not see “through” walls and foliage, or even a window. It only perceives direct and indirect emissions of thermal radiation. From the moment we are hidden behind such obstacles, it can not detect us … However, and what often makes any protection illusory, is that we do not know by definition when the enemy will watch us. It is challenging to walk always with a screen in front of you!
- On the other hand, and this is the problem of all the dissimulation methods offered by unique clothing and other obstacles, is that these methods are also going to block infrared coming from the background. We have already mentioned it. In other words, we will create a “black hole” of varying intensity in the landscape. The ideal would be the protection that obscures or mixes our thermal signature so that what a potential observer might see is based on the background. If you have ideas, they are welcome!
At the time of drones, he will find all kinds of ways to be identified. Even if no protection is perfect, it costs nothing to start with the basics of camouflage, including the lack of resources that exist regarding the concealment of its thermal signature …