Utilization of the SWIR Image Sensor in Firefighting

Solution for Securing Visibility in Smoke

Challenges

When a fire breaks out in a building, the rooms and corridors fill with smoke, obstructing visual sight. Without clear visibility, rescue and firefighting activities are much more difficult.

Solution

Compared to ordinary image sensors for visible light, SWIR image sensors capture the light of longer wavelengths. Long-wavelength light is characterized by its high transmittance, meaning it is less likely to be scattered by microparticles in smoke.
Using SWIR image sensors means the images are less impacted by smoke, making it easier to capture target objects even in a smoke-filled building where a visible-spectrum light sensor would not be able to secure visibility. This is useful for firefighters when, for example, surveying the affected area and ascertaining the actual situation at the site of a fire.

[Photographic illustration]

The images below were taken in a test using a visible spectrum, near-infrared (NIR), short wavelength infrared (SWIR) and long wavelength infrared (LWIR) camera (total of four cameras) set up in a line. Target objects include a clock, metal lettering, and panels set up in a box, and they were shot in an environment filled with smoke from a burning blanket. The target objects are illuminated using halogen lights that cover a wide spectrum of light from visible to infrared.
The SWIR camera has a 1,550 nm band-pass filter fitted in order to capture the range of long wavelength light that is more easily transmitted through smoke.

[Photographic result]

In the image captured by the visible spectrum camera, the target objects are completely hidden by smoke.
The NIR camera manages to capture to an extent the target objects through smoke, but visibility becomes compromised as the smoke gets thicker.
As the LWIR camera detects heat generated by the objects, the image cannot render details such as the clock’s hands or the difference in the materials of the panels. Moreover, the smoke radiates heat as it moves, and this heat distorts the image, resulting in poorer visibility.
The SWIR camera captures target objects with details such as the material differences and the objects’ contours while minimizing deterioration to visibility due to smoke.

As shown above, the SWIR image sensor can perform well in a fire situation to reduce poor visibility due to smoke and help with ascertaining the situation at the site of a fire.

Monitoring Forest Fires

Challenges

In wildfires and other large-scale forest fires, cameras mounted on drones and emergency rescue helicopters are used in order to efficiently understand the state of the fire over a wide area and assist firefighting efforts. However, if an ordinary visible spectrum camera is used, the precise locations of fire may not be easily identified as the view can be obstructed by smoke and vegetation on the ground.

Solution

The SWIR image sensor can capture the SWIR light emitted by fire. Even if a fire is difficult to distinguish from the colors of the surrounding environment in visible light, this sensor can detect flames clearly. As SWIR light is less prone to scattering in smoke, its highly transmissive property ensures the impact of smoke on visibility is minimal.

[Photographic illustration]

The video below shows a scene of the mountain burning, taken with a visible spectrum camera and SWIR camera. The SWIR camera video is shot in combination with a 1,550 nm band-pass filter. When the fire starts, very intense SWIR light is emitted from the location where the fire originally started. In order to reduce blooming (blurring and smearing of light in the image due to extremely bright incident light) caused by intense light, the amount of light the sensor received is adjusted by controlling the exposure time.

[Photographic result]

The image captured by the visible spectrum camera is blocked by smoke, and it is difficult to identify flames in the forest.
The SWIR camera reduces the visual impact of smoke and captures the scene with details such as the small source of the fire and the extent to which the fire has spread.

In this way, the SWIR image sensor can be utilized to monitor forest fires with drones and other equipment.

If you are interested in using SWIR image sensors, please contact us here.