Thermal Imaging and the Irish Coast Guard
In the 1980s, search and rescue aircraft began mounting sophisticated sensors such as night vision and thermal imaging equipment.
Forward-Looking Infrared or FLIR (pronounced fleer) systems enabled a pilot to see a warm human against a colder background, possibly even spotting a person in a forest.
Global Positioning System satellite navigation came into operation in the 1990s, enabling a helicopter to quickly find the location of a stricken vessel. Many military airmen were also equipped with GPS receivers so that they could provide their precise location to rescue aircraft. Civilian sailors and pilots often use a special satellite system that relays their distress signals to authorities.
Irish Coast Guard helicopters are equipped with sophisticated thermal imaging technologies and 360 degree mounted cameras.
Thermal imaging technology operates by capturing the upper portion of the infrared light spectrum, which is emitted as heat by objects instead of simply reflected as light. Hotter objects, such as warm bodies, emit more of this light than cooler objects like trees or buildings.
The amount of energy in a lightwave is related to its wavelength: Shorter wavelengths have higher energy. Of visible light, violet has the most energy, and red has the least. Just next to the visible light spectrum is the infrared spectrum.
Infrared light can be split into three categories:
- Near-infrared - Closest to visible light, near-IR has wavelengths that range from 0.7 to 1.3 microns, or 700 billionths to 1,300 billionths of a metre.
- Mid-infrared - Mid-IR has wavelengths ranging from 1.3 to 3 microns. Both near-IR and mid-IR are used by a variety of electronic devices, including remote controls
- Thermal infrared - Occupying the largest part of the infrared spectrum, thermal-IR has wavelengths ranging from 3 microns to over 30 microns.
The key difference between thermal-IR and the other two is that thermal-IR is emitted by an object instead of being reflected off it. Infrared light is emitted by an object because of what is happening at the atomic level.
The use of thermal imaging technology is not confined to search and rescue missions. It is also used in manufacturing processes to monitor heat build-up in machinery. It can also be useful for looking at how computer chips are working and it is increasingly relevant for determining the energy efficiency of houses and other buildings.
The Fluid and Heats Transfer Research Group at Trinity College, Dublin use thermal imaging and infrared cameras in a large number of applications.