Silent Sentinel - Thermal Imaging camera options

Thermal Imaging camera options

Thermal sensors and cameras create video images from infrared (heat) waves.

Thermal (Un-cooled)

Infrared is a part of the electromagnetic spectrum with wavelengths that are longer than visible light. Infrared is typically divided into near, mid, long and extreme and is measured in units known as microns or nanometers. Thermal technology detects infrared energy in the mid-wave infrared (MWIR) spectrum at 3-5 microns or long-wave infrared (LWIR) at 8-12 microns. Day or night, in any environment, every person, object and structure emits infrared waves.

The warmer an object, the more energy it emits. Infrared energy emitted by a viewed scene is focused through the specialized objective lens assembly of an infrared camera on to the camera's focal plane array (FPA). The FPA uses materials that respond by generating electrical impulses when infrared energy strikes it. These electrical impulses are then sent in the form of temperature values to an image signal processor that turns them into video data for presentation on a display.

Thermal technology provides clear, high-resolution images through smoke, haze, dust, light fog or even on the darkest night, so it often is the perfect choice for 24-hour surveillance. For example, thermal cameras can pick out vehicles that have been driven recently and still have warm engines or ground that has recently been disturbed by footprints or by burying hidden objects.

Uncooled thermal imagers use detectors that are either stabilised to temperatures between -30°C to +30°C or are not stabilised at all.

Benefits of uncooled thermal:

  • Low maintenance 
  • Lower costs
  • Reliable

Thermal (Cooled)

Two types of thermal technology are available, each with its own advantages.

For some applications, especially for long range detection, it is advisable to use “cooled” sensors. These sensors utilise a highly efficient cryogenic cooler that enables the detector to sense smaller differences in infrared emissions. Cooled technology can often capture images at a greater distance, produce a higher-resolution image and operate with smaller optics.


Thermal Image 320 Modules
Reference image: DA70, HFOV 70 degrees (Full tele-zoom view)

Type HFOV Width Fraction %
DA70 70 140 1 100.00%
DA40 40 72.79 0.52 52.00%
DA16 16 28.11 0.2 20.00%
DA9 9 15.74 0.11 11.00%
DA5 5 8.73 0.06 6.00%
DA3 3 5.24 0.04 4.00%

For 320x240px sensors.


Thermal Image 640 Modules
Reference image: DA70, HFOV 70 degrees (Full tele-zoom view)

Type HFOV Width Fraction %
DB44 44 80.81 0.58 58.00%
DB25 25 44.34 0.32 32.00%
DB18 18 31.68 0.23 23.00%
DB12 12 21.02 0.15 15.00%
DB9 9 15.74 0.11 11.00%
DB6 6 10.48 0.07 7.00%
DB25Z225 2.7 4.71 0.03 3.00%

For 640x480px sensors.

Cooled thermal imagers use detectors that are cooled to temperatures of 77 degrees Kelvin (roughly -200°C) or lower.

Benefits of cooled thermal:

  • Very sensitive to temperature change
  • High sensitivity = longer range
Thermal (un-cooled)

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