Radiometry will help to detect hidden objects through the passive measurement of the natural EM radiation emitted by these objects. Radiometers themselves do no emit any radiation. The differences in the power received will give an indication of the material the object is made of. TNO has developed a highly compact radiometer, thus opening up a multitude of new possibilities.
In many places, like e.g. discos, soccer stadiums and airports, access and admission control may now be improved significantly. Because a weapon hidden on the body will not remain hidden for long, if use is made of the TNO radiometer. Radiometers are also called millimetre wave cameras. The radiometer of TNO is based on a wavelength of 3 mm. At this wavelength, many materials, such as cotton, become transparent. Metals, on the other hand, show very little emission at 3 mm, and do not become transparent. However, because weapons are often hidden on the body, they will block the body emission at this spot, and this phenomenon may be shown as a contrast.
What makes the radiometer of TNO so special is its size, enabled by the increasing miniaturization of sensors, such as smart antennas. At this moment, TNO is working on perfecting the radiometer, at the same time investigating how we can make this system to operate more quickly, with an improved image quality.