How Thermal Imagers Work and How to Hide from Them

In the 1930s, primitive devices were invented to capture heat and make all heated objects visible in the dark. Almost 100 years later, these devices became modern thermal imagers, which have become indispensable human assistants. However, today, this optics is not ideal. Although it works effectively, it can still go unnoticed.

Nuances of thermal imaging devices work

Currently, dozens of companies are producing thermal imagers. Their models differ in appearance, size, functionality, efficiency and other aspects. The only thing that unites them is the operating principle. Considering the example of AGM Global Vision thermal imaging devices and the models of different companies, several main stages should be highlighted.

The operation of all thermal imagers begins with the detection of IR radiation. All objects emit it with a temperature above 0 degrees Celsius and are in the optics field of view. Then, the infrared radiation is focused on the matrix, which leads to a change in resistance in each of the millions of pixels. This process leads to the formation of an electrical signal. It is processed using special software, and a thermogram is formed. On it, each color corresponds to a specific temperature range. This image is transmitted to the display of the thermal imager, where it becomes available to the user. The entire described process occurs continuously, due to which it is possible to obtain a thermal picture in real-time.

Ways to hide from a thermal imager

Modern thermal imagers effectively cope with their work and can detect even weak thermal radiation. However, until they reach the peak of their development, people still have several ways to hide from their “eyes.” These can be done in several simple ways. However, they will be effective only under certain conditions, so it is not recommended to wholly trust each one.

Specialized clothing

The most modern way to hide from a thermal imager is to use specialized clothing. It is made of unique materials and becomes an obstacle that does not allow IR waves emanating from the human body to go outside. This virtually eliminates the possibility of detection by any thermal imaging optics. Such clothing has a two-layer structure. The first layer acts as a heat reflector. Most often, its fabric contains special polymers. They reflect IR radiation and do not allow it to go beyond the clothing. The second layer is camouflage. It masks a person in the area and reduces the likelihood of his detection. Combining these two layers allows you to blur or make the user’s silhouette invisible. In most cases, such clothing is made in a suit that covers all body areas except the eyes and the area around them. The suit is supplemented with special glasses blocking IR radiation to become invisible to thermal imaging optics.

Thermal insulation blankets

An effective way to hide from a thermal imager involves using a thermal insulation blanket. It operates similarly to the clothing described above but is simpler and more convenient. This is achieved by using lightweight and thin materials. They make thermal insulation blankets as compact as possible. Thanks to this feature, the products fit into a backpack and do not cause problems when worn for a long time. Most models of thermal insulation blankets are made of a unique foil film called mylar. It can reflect heat and does not allow it to go beyond the product. It does the same with light waves, hiding you from conventional night vision devices. Special capes are used as an alternative to blankets. They are large and allow you to protect various large objects (for example, cars) from a thermal imager.

Warm background

Thermal imagers can detect a person only if he is against a background of cold or hotter objects. If you deprive the optics of this advantage, you can hide from it. To achieve the desired result, you need to use a warm background. It should have approximately the same temperature as the body (36-37 degrees Celsius). In this case, the person will merge with the background on the thermal imager screen, and it will be impossible to determine his presence. During the day, in sunny weather, to use this method, it is enough to lie face down on the ground. Under such conditions, its temperature will be approximately the same as a person’s. This means that thermal imaging optics cannot highlight the silhouette against the general background. A similar effect can also be achieved using a brick wall. At night, everything is more complicated. After sunset, the temperature drops, meaning the surrounding objects become colder. In this case, you can find a suitable background only with some heat source.

Fire

You can become invisible to a thermal imager using many heat sources close to each other. It is impossible to find all this in natural conditions, so you must create them yourself. The best option would be small fires lit 1-2 meters from each other. Each of them will begin to emit heat, which will look like a wide spot of yellow or orange on the optics display. Together, small fires will create dozens of such places. Overlapping each other will fill the entire screen and make a person standing or walking among them invisible. Instead of fires, you can use any other objects that emit heat. They will also hide a person from the thermal imager and allow him to remain unnoticed.

Glass and other materials

Some materials blocking infrared radiation can hide a person from a thermal imager. The most accessible of them is glass. It will help you remain unnoticed in any environment. However, it can only be used in cases where you need to be in a static position and observe. Moving and carrying a heavy glass object that can completely block a person from a thermal imager will be inconvenient and extremely difficult. For such purposes, it is better to use plastic. It also blocks IR radiation but weighs much less. Black tarpaulin is another suitable material. It does not block radiation but reflects it unusually. Thanks to this, a yellow or orange spot (like a large, very hot object that does not look like a person) will appear on the thermal imager screen rather than a black spot, as in the case of glass or plastic.

How can the likelihood of detection by a thermal imager be reduced?

Only the methods described above can make you completely invisible to a thermal imager. Several other methods can partially hide from the device and reduce the likelihood of detection. They all require precision in the actions performed or using additional devices.

The easiest way to reduce the risk of detection is to remain motionless. In this case, less heat is generated, which means the chances of remaining unnoticed in the dark will be higher. A similar effect is achieved by making very slow movements. The second method is to wear warm clothes. It will create severe discomfort, especially if you do this in the summer or early fall, but it will reduce the likelihood of detection by a thermal imager. Thanks to such clothes, you can partially merge with the surrounding background on the heat map. At the same time, open areas of the body (neck, face, hands) will remain visible to optics, but it will be challenging to identify a person by them.

Using a grid is another way to reduce the likelihood of detection by a thermal imager. Thanks to this product, the heat emanating from the body will be partially dissipated, making it less noticeable to optics. In addition, the grid will complicate identifying a person, which is also a significant plus. Finally, the last method is to use dense vegetation. Several trees or bushes will not allow the heat trace to escape the thermal imager. But if there are many, a dense obstacle will be formed through which the optics can capture only part of the heat emanating from a person.

In everyday life, there are many situations when it is impossible to do without a thermal imager. This device is widely used by people worldwide and is their indispensable assistant. At the same time, it continues to improve. Today’s models still give a person a chance to remain unnoticed, but the situation may change in the future. If this happens, thermal imagers will become more valuable and popular optics