Thermal Imaging Detection

Individual units should be evaluated by their specific performance attributes

There are numerous factors that affect the distance for Thermal Imaging Devices. In this article we will have a look at factors that affect this distance.

thermal imaging

“Often, the first question that people interested in buying a thermal imaging camera ask is “How far can I see?” This is a very reasonable question to ask, but it defies any simple answer. All thermal imaging cameras are able to see the sun which is more than 146 million kilometers away from Earth. But it would be totally wrong to say that all thermal imaging cameras can detect security threats at this distance.”

Thermal imaging is a technology that enables detection of people and objects in total darkness and in very diverse weather conditions. A typical application for thermal imaging is border security, where most threats occur at night. Watchtowers spaced at 4km intervals or more have to be able to detect threats at ranges up to 2km or more to guarantee full coverage of the border. Knowing how far you can see with a thermal imaging camera and at which distance you can detect a possible threat is of the utmost importance. The distance you can see a given target with a thermal imaging camera is called the “range” in the thermal imaging industry. To correctly determine the range of a thermal imaging camera requires some sophisticated modeling. There are many variables to consider including the type of thermal imaging camera you are using, the type of lens you are using, the nature and size of the object you want to detect, the atmospheric conditions and the very definition of what it means to “see” a target.

“Seeing” an object – To define what is meant by “seeing a target”, the so-called Johnson’s criteria can be used. John Johnson, a Night Vision & Electronic Sensors Directorate scientist, developed criteria that relate to the effective range of infrared cameras. Although developed for the military (hence the use of the term “target” to refer to the object of interest), the Johnson criteria are widely used in the commercial marketplace to characterize thermal imaging systems. According to these criteria a distinction needs to be made between degrees of “seeing” a target:

Detection: In order to detect if an object is present or not, its critical dimension needs to be covered by 1.5 or more pixels. 1.5 pixels in a staring array is equivalent to 0.75 “cycles”, which is the unit of system resolution originally used in Johnson’s definition.

Recognition: Recognizing an object is defined as seeing what type of object it is. It means being able to make the distinction between a person, a car, a truck or any other object. In order to recognize an object it needs to be subtended by at least 6 pixels across its critical dimension.

Identification: This term is often used in the military sense of the word, which means seeing if someone is “friend or foe”. In order to do this, the critical dimension of the object in question needs to be subtended by at least 12 pixels.”

FLIR Breach PTQ136

The FLIR Breach PTQ136 is a multifunctional thermal imaging monocular that can spot the heat of any suspect or object in total darkness. FLIR Breach is the best combination of size, weight and thermal resolution.

GSCI - QUADRO-S Thermal Sight

The QUADRO-S is the augmented vision weapon-mountable system for tactical surveillance, observation and engagement at short- and medium-range distances. It is the next big step in the evolution of advanced detection systems. The unit is small and lightweight, and yet made of a hard-anodized aluminum for added strength and shock resistance.

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