Thermal Imaging
Basic Thermal Imaging (which detect and convert energy in much
“...aircraft, automobiles, Technology & Terms the same way as common cameras, but
are made of different materials) would be
people, animals and All objects emit infrared energy. Infrared ‘blinded’ or flooded by their own
energy is just one part of the electro - radiation. The drawbacks of cooled
foreign objects can be magnetic spectrum that encompasses thermal imaging cameras are that they
radiation from gamma rays, X-rays, ultra are more expensive than uncooled
detected, identified and violet, a thin region of visible light, infrared, cameras. However, cooled infrared
microwaves and radio waves. These are all cameras provide superior image quality
recognised at great related and differentiated by wavelength. and can detect, recognise and identify
Generally, the higher an object’s objects at great distances (0 to >30km).
distances, day or night, temperature, the more infrared radiation it Uncooled thermal cameras typically are
emits. Thermal imaging cameras detect sensitive to LWIR radiation and use a
through most smoke, this radiation in a way similar to the way an detector that operates at ambient
ordinary camera detects visible light. temperature. As they do not have cryogenic
smog and fog..” Images from thermal imaging cameras are coolers, uncooled thermal imaging
monochromatic because the cameras are cameras are smaller and less costly.
generally designed with only a single type However, resolution and image quality are
sensitive airport areas as a way to augment of sensor responding to the infrared lower than cooled detectors. This is due to
existing surveillance capabilities and radiation wavelength range. difference in fabrication, limited by
enhance threat detection to make our Within the Infrared wavelength band, two currently available technology. They also
airports and the millions of travellers that distinct IR wavelengths pass effectively are effective in identifying objects at
move through these facilities safer. through air: distances lower than 3km, with many
Use of thermal imaging technology has having smaller focal length lens (<100mm)
increased dramatically in the last decade. circle6 Mid Wave IR (MWIR) – ~3-5µm that are effective to half that distance.
Predominately used by the military for circle6 Long Wave IR (LWIR) – ~7-14µm Which is better: MWIR or LWIR thermal
battlefield situational awareness, the imaging cameras? Frankly, there is no easy
technology’s continued development has Thermal imaging cameras can be readily answer, as the choice is dependent on the
resulted in increased performance and distinguished by the detector type following factors:
dramatic decreases in cost. As a result, contained within the camera. Essentially,
many non-military users, such as two sensor types are available: cooled and circle6 Site Geographic Location/Climatic
commercial and government aviation and uncooled thermal imaging detectors. Conditions
airport authorities are discovering thermal Cooled detectors typically are sensitive to circle6 Overall Atmospheric Transmission
imaging and the benefits it has to offer. MWIR radiation and are contained in a circle6 Source Temperature
Thermal imaging cameras, unlike vacuum-sealed case and cryogenically circle6 Solar Effects
conventional cameras, produce clear video cooled. Without cooling, these sensors circle6 Target Range
images without the need of illumination
and can penetrate fog, smoke, smog, dust
and haze. The cameras provide remote
video imagery of AOAs and Security
Identification Display Areas (SIDAs),
exposing details of aircraft, automobiles,
people, animals and foreign objects on
active runways and taxiways as well as the
perimeter areas of the airport. Thermal
imaging cameras are not adversely
affected by airport or aircraft high-intensity
lighting and provide a consistently superior
image day or night.
A wide variety of thermal imaging
cameras are commercially available having
the same analogue and/or digital
interfaces as conventional cameras. This
allows thermal imaging cameras to be
used and interfaced with existing CCTV
video command, control, communications,
recording and display equipment. However,
as thermal imaging technology is relatively
new to the commercial marketplace, and to
the commercial user, there are important A thermal imaging camera protecting the perimeter of LaGuardia airport in NY
basic technology terms to understand. (Credit: AxSys)
Aviationsecurityinternational April 2009 www.asi-mag.com 17
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