What are the components of a Thermal Imaging?
The Thermal devices, whether monocular handheld, Clip-On attachment, or thermal riflescopes, are devices of extreme complexity, which is why they become the best companion in situations of detection, recognition, and identification of objects with heat in the night and diurnal contexts. They have a large number of components, and the variation of them causes the quality of the image, detection range, and mainly, the price to be modified.
These components and parameters are, the type and resolution of the thermal sensor, the pixel pitch of the thermal sensor, Thermal sensitivity or NETD (Noise Equivalent Temperature Difference) of the thermal sensor, objective lens diameter, field of view, display type, display resolution, functions (rangefinder, sensor motion, video recorder, and photography), electronic processing unit, operating time on battery, magnification, shock resistance (weapon recoil), weight and size, etc.
What parameters to analyze to know which thermal is better?
Most users are not experts in thermal technology, that is why this article aims to be able to differentiate which thermal is better according to the user’s needs, with a small analysis of the most influential components.
1) Resolution of thermal sensor:
The resolution is indicated as the total number of pixels (384×288, a total of 110,592 pixels). The higher this value, the better the image quality.
2) Pitch pixel of thermal sensor:
Pixel pitch is the distance between the centers of two pixels on the thermal sensor and is measured in microns (µm). The lower this value is (12 µm compared to 17 µm) the more pixels will fit into the same area. Therefore, the image will be sharper and the thermal will be able to detect, recognize and identify objects at greater distances, compared to the same objective lens diameter.
As can be seen, the detection and recognition range increases significantly when using a pixel pitch of 12 um instead of 17 um. That is why, this parameter becomes essential when choosing a thermal vision device.
3) Thermal Sensitivity or NETD (Noise Equivalent Temperature Difference):
This parameter is measured in millikelvin (mK) and could be summarized as thermal sensitivity. The word noise refers to the context, to what we do not want to detect. This means that when the temperature of an object drops low enough, the heat signal it radiates can mix with that of the context, to the point that the thermal sensor cannot distinguish the heat signal from the context; this situation would occur more commonly in summer.
The lower the NETD value, the better the sensor will be able to register small temperature differences, that is to say, that a sensor with a high NETD, which only distinguishes the different temperatures when these differences are high, will not distinguish the temperature difference between the parts of the animal body; while a low NETD, which distinguishes different temperatures, even if their differences are small, will indicate which parts of the animal have the most heat.
3) Lens diameter:
The maximum detection range depends on several factors: with the same components, above all, the same pixel pitch, the larger the diameter of the lens, the greater the detection, recognition and identification range of the thermal device.
As for the types of ranges we can discern:
a) Detection range: the object is visible at a certain distance, but the type of object cannot be determined.
b) Recognition range: the type of object can be defined, the observer can discern what is being observed, that is, if it is a human being, an animal, a car, etc.
c) Identification range: the observer can assess not only the type of object, but also its characteristic features (male wild boar, what person it is, etc.)
5) Functions:
a) Algorithmic Intelligent (AI) Rangefinder.
It uses software similar to the stadiametric rangefinder, but automatically, it has a range of approximately 300 meters; In about of precision, it is not as precise as the laser rangefinder (LRF), however, in about practical, the AI rangefinder identifies which object it is, it can give several data at the same time and automatically. With human is very precise.
b) Laser RangeFinder (LRF).
The device sends a laser beam to the object, bounces and returns to the rangefinder, it takes the time that the laser pulse takes to go and return. It’s a precise accurate method, but it only works if there’s no object in between.
c) Stadiametric Rangefinder:
It allows to know the distance knowing the size of the object, the data of the size of the object is loaded in the software, the user simply has to place a line below and another above the object.
d) Sensor Motion.
The thermal device detects the animal when the user is not looking and sends a notification to the watch or mobile app providing information on the type of object and the distance at which it was found.
e) Video recorder and photography.
The thermal devices include Wi-Fi and mobile apps that provide more practical and satisfactory use. This allows for video recording and taking a photos. Also, some devices can record with audio.
Conclusions:
Below is a scheme that summarizes the subjective evaluation of the components and parameters. So that you can differentiate between a thermal device and others.
After the components are known, it is known which is better than another. You can make a comparative table, like the one shown below, to be able to compare quickly between one and the other.
