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Application: Image Fusion With Long Wave Infrared (LWIR) And Short Wave Infrared (SWIR) or Hinted SWIR

Hinted SWIR

In a concept called Hinted SWIR™, Sensors Unlimited is developing the means to maximize target detection and recognition through a combination of long wave infrared and short wave infrared sensors.


Shown here is a simple prototype employing a DRS uncooled microbolomoter for LWIR sensing packaged alongside a Sensors Unlimited SWIR camera. Both cameras have approximately the same field of view to simplify the fusion of the two images. For this prototype, Sensors Unlimited employs a fusion engine made by Equinox.


SWIR/LWIR Fusion Demo
SWIR/LWIR fusion demo.


LWIR is excellent for detecting thermal signatures of people and vehicles as a result of the temperature difference between them and the background environment. This type of sensor sees thermal emissions and is in wide use around the military for thermal weapon sights as the LWIR image component shows it does a very good job in detection of thermal targets.


SWIR, on the other hand, sees in reflected light, and because of its shorter wavelengths is also able to give higher resolution and more details to images. Thus, an effective combination of these two wavelengths would allow very good detection along with positive target recognition.


In a technique called Hinted SWIR™, Sensors Unlimited uses LWIR detection to “hint” the SWIR image to highlight the areas where the user might want to focus in order to detect and identify targets. As shown here, the “thermal hints” use false colors to give relative temperature values behind the SWIR images.


5:20 am October 20, 2009, a cold, clear morning in the Princeton, NJ area (37°F). A deer seated in a meadow at 50m range and two other deer at ~250m distance stand out clearly in the thermally-hinted image. SWIR provides detailed scene contextual clues.  Thermal imagery provides only the heat signatures. SWIR/LWIR Fused Image SWIR/LWIR Fusion Airborne Image
Thermally-hinted NIR/SWIR night images of deer.
Thermal hints in this fused image accelerate detection of people and vehicles.
Thermally hinted NIR/SWIR urban night scene from an aerial perspective.

In an operational system, we envision the thermal hints could be turned off once the target location has been cued in the image, then the user would use primarily SWIR-only for target identification and action.


NIR/SWIR image with 25% Thermal Hints NIR/SWIR Image Insert
6:45pm October 3, 2009, a wet evening in the Princeton, NJ area (65°F) after heavy rain. Two people crossing a parking lot at 100m range stand out clearly in the thermally-hinted image. NIR/SWIR provides detailed scene contextual clues. The thermal hints cut through the clutter to highlight human and vehicle activity. The zoomed in NIR/SWIR insert provides detailed view.

To learn more about Hinted SWIR™, please read our article titled "Sensor Fusion Payloads - The Key to Information Rich Imaging" that ran in the December 2009 issue of Unmanned Systems Magazine.

Many SWIR camera capabilities are considered sensitive. If you would like to learn more about SWIR capabilities for the military, you can register at a special web site, You must be a US Government employee or a USG contractor and be a US Citizen to access this site.

Contact Sensors Unlimited to see how SWIR Imaging can meet your needs!


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