Thermal Imaging Camera: How it works and why it may be necessary

July 9, 2019.

A thermal imaging, thermography or infrared camera is a camera that displays an image of the thermal radiation emitted by a body. In recent years, thermal imaging cameras have gone from being a product that only appeared in Hollywood films and in news related to war to be accessible to everyone, thanks to new production methods that have cheapened the cost of this equipment.

PROMAX makes available to all professionals a full range of professional thermal imaging cameras for sectors such as industrial, medical, construction and certification as well as general purpose thermal imaging cameras. They can detect temperatures from -20 to 350 ºC (-4 to 662 ºF) depending on the model.

PROMAX thermal image cameras
PROMAX thermal image cameras

How a thermal imaging camera works?

All bodies above absolute zero (-273 °C) emit infrared radiation (heat). In general, the larger the emitted radiation, the higher the temperature of the body. This radiation is invisible to the human eye and its range in the electromagnetic spectrum is between visible light and microwave radiation. Specifically, the wavelength of the infrared is between 0.7 and 1000 microns. Within this wide range, thermal imaging cameras work in a range known as thermal infrared, which is where the most common land surface temperatures are, between 8 and 14 microns, which is approximately between -20 and 350 °C.

Image in the infrared spectrum of an electrical panel taken with the thermal camera model IR-282
Image in the infrared spectrum of an electrical panel taken with the thermal camera model IR-282

The thermography camera has a heat sensor called microbolometer. When it receives infrared radiation it warms and changes its electrical resistance. This change in resistance is measured and compared to a given temperature. A colour is assigned to each temperature which creates a coloured image that will be show on screen. The advantage of these sensors is that they can work at room temperature and does not require refrigeration, so they are cheaper than the sensors for military use.

Applications of the thermal imaging camera

The detection of these infrared radiations, impossible to see with the naked eye, is particularly advantageous in many situations and can help to prevent many unwanted moments. Non-uniformity of temperature typically indicates a failure or critical point, either by increased blood flow that occurs in an internal injury from an animal or heat leakage which can occur in the critical point of a pipe. Below are listed a few applications:

Industrial servicing

Detection of hot spots in electrical panels, engines and any type of machines
Detection of hot spots in electrical panels, engines and any type of machines. This information can be the key to avoid service interruptions or accidents.

Design, manufacturing and servicing of electronic circuits

Detection of hot spots in a circuit board to detect failures and to anticipate operation problems
Detecting hot spots in a circuit board can help us to detect failures and to anticipate operation problems.

Locating living beings: Rescue and safety

Locating living beings in the dark
Given the fact that generally living beings have a body temperature higher than the environment temperature, it is possible to find them in the dark.

Construction and maintenance

Identifying poorly insulated points
Isolation and energy saving. Thermal cameras allow identifying those points whose poor insulation allows heat loss. They also can be used to detect leaks in pipes, dampness, to check heating systems, etc.

Chemistry and derivatives

Verification of container contents
Verification of container contents. For example in the industry sector they allow to find out how much gas is left in a given hard to reach pressured cylinder.

Air conditioned and heating circuits

Identifying cold or heat losses
It is possible to identify at a glance the points of the circuit where a cold or heat loss is being produced by just displaying the thermal image.

Preventing fires at the electric power distribution network

Thermography for electric power distribution networks, both industrial and domestic
Early identification of overheating points can help prevent fires, short circuits and hazards to people in electrical distribution networks, industrial electrical installations and subscriber homes.

Plumbing: Locating leaks in water piping

Locating leaks not readily apparent in water pipes
With a thermal image you can instantly locate the point where a domestic water piping or a drain is causing leaks, even if these are not readily apparent.



  • Heating of faulty electrical components.
  • Friction in engines or electrical machines.
  • Imbalance charges.
  • Leaks or blockages in pipes.
  • Bad electrical connections.
  • Prediction of potential fire or damage.
  • Overload of electrical circuits.
  • Levels in deposits.
  • Critical points in pipes.
  • Hazardous chemical reactions.


  • Energy efficiency.
  • Heat leaks.
  • Moisture.
  • Poor insulation.
  • Water Leaks.
  • Temperature distribution in heating systems.

Security and other

  • Detection of living being in emergency situations (landslide, earthquake...).
  • Detection of possible fire outbreaks.
  • Research.
  • Detection of stowaways on border crossings.
  • Security perimeter.
  • Home invaders animals.
  • Wildlife viewing and outdoor activities.

As you can see, uses of the instrument are diverse. We have only mentioned some of them that are being used at present. In the future there will be many more as its use is extended. For more information:


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PROMAX is a leading manufacturer of test and measurement systems, broadcast and TV signal distribution equipment. Our product lines include measuring instruments for cable TV, satellite TV, broadcast, wireless and fibre optics networks, FTTH and GPON analyzers. DVB-T modulators, IP streamers or IP converters (ASI, DVB-T) are among the company’s latest developments.