An expanding list of practical applications

The list of applications for the Short Wave Infrared is limitless. The imagers have been used in paper manufacturing to observe moisture content, sorting plastics in recycling and in art restoration for looking through paint pigments to charcoal underdrawings.

The applications are too numerous to list here but they break into several categories:

  • Spectroscopy for sorting
  • Moisture detection
  • Thermal imaging
  • Imaging what can’t be seen in visible
    • Night vision
    • Imaging lasers

SWIR imagers have the advantage of being able to be used with glass and plastic optics instead of expensive Germanium or exotic materials used with longer wavelength infrared detectors. This makes them able to work in industrial environments where the cameras can be placed behind glass shields or with long or wide lenses.


Imaging Through The Atmosphere

SWIR 1280SCICAM imaging

Shortwave infrared has been shown to image though the atmosphere better than visible. (SPIE reference)  The longer wavelength of light enables better transmission and less scattering than visible light due to the size of water and dust particles in the air  In the example at the right one can image nearly as well with the 1.3Mpixel SWIR image versus the >5Mpixel image in the visible and this was a clear day.  In hazy conditions the SWIR improves dramatically.  Imagery was taken with the 1280SCICAM using a 25mm f/1.4 Optec lens which mostly transmits from 900 to 1700nm. 

SWIR 1280SCICAM imaging

Chemical Detection

SWIR for Chemical Detections

Different chemicals absorb light differently in the SWIR spectrum.  One can use these various absorption spectra to differentiate chemical types.  In the example below broad band light is used to image four chemicals.  All four chemical looks like clear liquid in the visible.  Using broad band SWIR light one can see light is absorbed differently leading to the chemicals appearing different (darker or lighter).   Using a prism or spectrometer to seperate the light into individual wavelengths allows one to find the chemical fingerprint for many species in the SWIR band. 

Imagery taken with 1280SCICAM and Optec 25mm F1.4 SWIR lens.

SWIR for Chemical Detections

Thermal Imaging in SWIR

Imagery of Objects in the SWIR

All objects emit light in the infrared range. The hotter the object the more light that is emitted and the wavelength of the peak intensity moves to shorter and shorter wavelengths. Shortwave infrared (SWIR) is used in many applications for measuring objects >100°C.  Many time a Long-wave infrared (LWIR) or Mid-wave infrared (MWIR) imager is used because of its greater sensitivity and its ability to measuring objects at lower temperatures but Short wave infrared has the advantage of using glass optics.  SWIR can image through glass or plastic windows something that MWIR and LWIR can not.  SWIR also has the ability to use reflected light as well as emitted light enabling one to more easily differentiate objects.  In this case one can see the electrical cords from the soldering iron and to see the 1.3μm light in the integrating sphere on the left.

Imagery of Objects in the SWIR

Moisture Detection

In the SWIR band there are several wavelengths ranges where light is highly absorbed.  These absorption bands enable users to image where water is present.  In this case two liquids are on a grey piece of steel.  One liquid is water and the other is motor oil.  In the visible they are difficult to tell apart.  In the SWIR it is very clear which is water (black) and which is oil (lighter grey than steel).  In the visible band a color camera would have difficulty imaging which liquid is which.  The amount of moisture can be measured by calibrating the amount of light reflected from the given object.  SWIR cameras are used in paper manufacturing to determine the dryness of the paper.