Thermal Camera Selection

1. Detector Resolution

The most important issue in choosing a thermal camera is the actual resolution of the detectors to be selected. The high resolution of the detector increases the range of the camera and provides better images. In this way, diagnosis and classification can be made from longer distances. For example, a 1280 x 720 resolution camera will have 2 times more range than a 640x 480 resolution camera.

640 x 480 Resolution 1280 x 720 Resolution

2. Lens Size

Lens size is an important factor affecting the range in a thermal camera. The larger the lens, the greater the range. However, the enlargement of the lens causes a narrowing of the field of view. In other words, a field of 24 degrees can be seen with a 13 mm lens, while a field of 12 degrees can be seen with a 35 mm lens. The advantage of the narrow angle is that it facilitates the identification of the target, while the disadvantage is that it reduces situational awareness due to the narrow field of view. For this reason, cameras with optical zoom feature turn disadvantages into advantages, enabling both perimeter surveillance and identification of the target.

Point of View	Lens	Detection	Recognition	Identification
25 Degrees	25 mm	2800 m	710 m	360 m
12 Degrees	50 mm	5100 m	1320 m	660 m

3. Detector Pixel Pitch

Pixel pitch in detectors is very important for the quality of the resulting image. The wider it is, the blurrier the image will be. Therefore, the image quality will decrease and targets will be harder to detect. A pixel pitch of less than 17 µm will provide a good result.

4. Thermal Sensitivity

Thermal sensitivity is the temperature difference that the detector can measure between two points. For example, a detector with a thermal sensitivity of 0.2 degrees will show a 35 degree point and a 35.2 degree point as a single point. Therefore, the smaller the thermal sensitivity, the more accurate the target discrimination will be. This will affect the range of the camera and will result in a smoother image. It should be less than 35 mK for uncooled thermal cameras and less than 25 mK for cooled thermal cameras.

5. Screen Format

The screen format supported by the thermal camera is important for increasing situational awareness. 640x480 detectors support the 4:3 format, so most screens have black bands around the edges. In order to prevent this, some cameras do enlargement, which causes image loss. It can show a wider area in 16:9 format.

6. Turbulence Filter

Thermal cameras are affected by evaporation due to environmental temperature, which prevents blurring of the image and detecting some targets. There is a lot of turbulence, especially on areas such as sand and asphalt. It is an important issue in target detection that the camera has filters to reduce this turbulence.

Filter off Filter on

7. Detector Life

The most important part of thermal cameras are their detectors. Especially in cooled type detectors, the cooling system needs maintenance during certain working hours. These maintenance parts are the most costly parts. In some cases, it costs close to 1/4 of the camera. Therefore, the longer the maintenance period, the lower the long-term maintenance cost of the camera. While calculating the purchase cost, attention should be paid to this issue, and detectors with a maintenance period of more than 10,000 hours should be selected. This must be added to the selection criteria as an evaluation item. Maintenance-free cameras up to 25,000 hours are also available.

8. Detector Material

The material of the detector is important in terms of sensitivity and reaction rate and causes it to be affected by environmental noise. Especially in cooled cameras, Indium Antimonide (InSb) detectors give better results.

Thermal Camera Selection

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