Fascinating Facts
What is an Argus4 thermal imaging camera?
The Argus thermal imaging camera is a valuable tool for fire and rescue personnel.
The camera is used for:
- Rapidly identifying the seat of a fire, even when it is hidden.
- Measuring the approximate temperature of the seat of a fire.
- Monitoring the spread of fire and the effectiveness of firefighting measures.
- Searching in smoke or darkness to find people who need rescuing or objects that present a hazard.
- Measure the temperature of closed doors to determine whether it is safe to open the door
The Argus camera also has many other uses. For example, it can facilitate the pinpointing of someone who has fallen into a river or the location of temperature changes in technical systems.
How does a thermal camera work
All objects give off energy in the form of electro-magnetic radiation. The name given to this radiation depends on its wavelength. Radiation with a wavelength slightly longer than that of visible light is called thermal or infrared radiation.
The thermal camera has a sensor that detects this thermal radiation and converts it into electrical signals.
These signals are converted back into an image on the camera’s LCD screen. This makes it possible to see the thermal radiation, which is otherwise invisible to the human eye. The greater the temperature/thermal radiation differences between the objects being viewed, the higher contrast of the image.
How can the thermal camera measure temperature?
By measuring the thermal radiation from an object, the camera can calculate the temperature, without having to touch the object.
The camera’s sensor (a microbolometer) has 19,200 pixels (160 x 120). The camera displays an indication of the temperature at the centre of the picture by averaging the temperature readings for the middle 16 pixels (4 x 4 array). The temperature indication is shown as a number in Centigrade or Fahrenheit on the LCD screen to a resolution of 1°C. The image displayed on the LCD screen can display temperature differences to an even greater resolution – as low as 0.1°C.
So that the camera can show a good temperature indication and to give a clear picture, it must occasionally be automatically recalibrated. During this automatic calibration the image freezes for a fraction of a second and a clicking sound may be audible.
How can the thermal camera see in the dark and through smoke?
The camera does not depend on visible light. It measures electromagnetic radiation that has a longer wavelength. This is why, even in total darkness, it can create an image of its surroundings.
Unlike visible light, thermal radiation is not obscured by smoke, so the camera can effectively see through smoke as if it wasn’t there. However, the camera cannot see through objects or substances that absorb thermal radiation, for example glass or water.
Both the left and the centre cups contain hot coffee, raising the temperature of the cup, making it visible to the thermal imaging camera. Because the glass plate blocks any thermal radiation from the right side of the centre cup, this is not shown on the camera’s LCD screen.
The cup on the right is empty and is also not shown on the LCD screen. This is because it is at the same temperature as its surroundings. Thus, the camera does not register any difference in thermal radiation.
Shiny objects (e.g. glass and polished metals) can reflect thermal radiation in exactly the same way that they reflect visible light.
This is how a thermal camera works
A thermal camera can work in complete darkness. This is because the camera measures thermal radiation and not visible light. Based on the thermal radiation that hits the sensor through the lens, the camera creates an image that is displayed on its LCD screen. The technique of creating images from measurements of thermal radiation is known as thermography.
