Why and when should you use Infrared Sensors? Are all Infrared Imagers able to measure temperature? Xenics has the answers. Xenics is a leader in the manufacture of Infrared camera products covering the most active IR wavelength ranges from 1 up to 14 micron. The Xenics IR cameras cover the Visible Near Infrared VIS/NIR, Short Wave Infrared SWIR, Mid Wave Infrared MWIR and Long Wave Infrared LWIR. Xenic’s expertise and flexibility allows them to offer and develop custom-made infrared products to suit clients’ requirements.

Xenics specialises in the design and manufacture of Infrared Cameras from 1 to 14um. They provide InGaAs cameras and MCT cameras for Short-Wave Infrared, InSb cameras for Mid-Wave Infrared and Micro bolometer cameras for Long Wave Infrared imaging.

What is Infrared Light?

Light is part of the continuous spectrum of electromagnetism that ranges from the Radio Waves we use for communications to Gamma Rays emitted by the Sun. These different electromagnetic bands differ purely in their wavelength. Light ranges from approximately 100 nanometres to 100 micron. Visible light takes up only a small part of this - from 400nm to 700nm. The light below 400nm is Ultraviolet and the light above 700nm is Near Infrared and Infrared. Sunlight emits ultraviolet, visible and infrared with infrared accounting for 47% of the sun's luminous efficacy.

Why use Infrared Light?

Infrared light is not visible to the human eye and this property is what makes it useful for some applications. Surveillance infrared cameras and security infrared cameras rely on the fact that infrared is not visible. Intelligent Traffic applications such as speed cameras, Automatic Number Plate Reading also use infrared imagers that use this property. IR cameras are also used for night vision when there is very little visible light but enough natural infrared light from the night glow.

Another property of infrared light that makes an IR imager useful is its ability to penetrate the surface of some materials. Its longer wavelength allows it to "see through" material that visible light is unable to. For example infrared sensors are used for detecting sub-surface defects in silicon for semiconductor manufacture, to penetrate inks for currency forgery detection and to penetrate paints for art history analysis. Another use of infrared cameras where this property comes into play is the inspection of fruit. Penetrating the surface of the fruit allows infrared imagers to detect bruising below the surface that is not visible to the eye.

There are many defence thermal camera applications that rely on their covert nature as with Surveillance and Security. There are others such as ballistics and rocket tracking that detect the infrared emission from the projectile drive.

Modern telecoms uses infrared light and fibre switching with infrared light as the medium for digital communications. . IR sensors are used for light beam profiling for test and diagnostics.

Perhaps the most commonly associated application to Infrared Cameras is Thermal Imaging. Infrared imagers (thermal cameras) have the ability to measure the temperature of materials. Materials emit infrared light and the hotter the material the more infrared and the shorter the wavelength of infrared light it emits. For this reason thermal cameras that are used to measure at around room temperature work with wavelengths around 12um while at 300°C 1.7um infrared light is used. Thermal cameras with InGaAs sensors that sense up to 1.7um can measure temperature in a range from 300°C to 800°C. Thermal cameras with MCT sensors can measure lower temperatures and micro-bolometer thermal cameras can measure down below room temperature.