Illumination for applications outside the visible spectrum
SWIR (Short Wave Infrared) is a very interesting spectral range. Images created by SWIR cameras are similar to those taken by a monochrome CCD camera, but the detector material (InGaAs) is sensitive in a wavelength band where water vapour causes maximum absorption and silicon is transparent.
It should be noted that an adaptation of the optical elements built-in the illumination is necessary as the diffusion efficiency of a diffusor depends on the wavelength. Consequently, you need to use a specific material for the diffusor used in a SWIR light. It's the same for other elements that interact with the light such as the focus lenses in a line light or the reflection paint in a dome light.
The advantages to using SWIR illumination
Infrared imaging allows you to avoid X-ray technology: consequently you save money, reduce the administrative overhead and the efforts to protect material and employees against X-Ray radiation.
Despite the higher cost for SWIR LEDs compared to halogen lights the LEDs are getting more and more popular for Infrared imaging as they do not emit as much heat as the halogen bulbs. This is especially of benefit in food applications.
Fields of application
SWIR illumination can be used for infrared imaging to detect features that are not apparent in visible wavelengths. Typical applications are inspection of silicon wafers or solar cells, recognition of safety features, detection of fill levels of liquid in opaque receptacles or of transparent liquids in glass bottles, detection of food moistures for sorting of fruits or vegetables, control of plant growth etc.