A new generation of thermal imaging technology offering much higher resolution and sensitivity is to be developed by a UK research team comprising engineers from Qinetiq, Thales UK, Selex Sensors and Airborne Systems.
Heralded as the third generation of thermal imaging cameras, the technology uses a matrix of more than a quarter of a million tiny infrared detectors. This array will allow the camera to provide an image that is more than twice as sensitive as any existing thermal imaging camera, according to Peter Dennis, Qinetiq’s project leader.
‘Third generation thermal imaging will revolutionise the industry in much the same way as digital cameras changed conventional photography,’ he said. ‘It works in much the same way. The matrix of detectors cover the whole field of view and detect it all in one go, each tiny sensor picking out a separate point in the field of view.’
Today’s second-generation infrared cameras use a linear array of 768 detectors with a mirror that scans from left to right across the field of view. When this technology was first developed in the 1990s it provided around 700 more individual ‘picture points’ than the first generation, developed in the 1980s.
The new system will bring down the cost of a thermal imaging camera considerably, according to Dennis, as the digital technology uses no mechanical moving parts. The MoD wants a suite of cameras that can work in a wide range of conditions and so the team is developing three different imagers, each one sensing in a different part of the infrared spectrum.
The sensors are made from an alloy known as cadmium mercury telluride (CMT), an extremely fragile material which is particularly sensitive to infrared light. It is grown in vacuum conditions in the laboratory, and its chemical composition can be altered to provide the sensors with different thermal imaging properties.
According to Dennis some of the biggest challenges are in producing this unique material.
‘CMT is so soft it can be scratched with a paper tissue — so the challenge is to be able to produce it with uniformity and keep it clean. Just a 1mm speck of dust would wipe out a large portion of the image,’ he said.
Innovative integrated circuits are connected to the CMT in vacuum conditions, and the team had to develop a sophisticated read-out circuit to retrieve the data from the sensors.
According to Dennis, the potential applications for the technology are huge.
As well as developing advanced night vision sensors for armoured military vehicles, the system could also be used in future infrared search-and-track systems as well as in missile seekers for precision attacks.
The first working prototype is due to be completed by 2008.