Toward Polarization-Enabled Wildfire Detection

Wildfire season in the United States is becoming longer with more intense fires. The NationalInteragency Fire Center has reported an annual increase in the burned area of 800 km2/yr since1980 [1]. Currently, widespread techniques for detecting wildfires rely on humans in watchtowers,satellite imagery, and strategically placed sensors or cameras. These techniques have shown theability to detect wildfires within 24 hours or as short as 1 minute after ignition. However, thereare several disadvantages to these methods. Watch towers and satellites are limited in spatialcoverage and require the wildfire to be large enough for detection at large distances. Sensors andcameras offer increased spatial coverage but require that the wildfire be within the field of viewof the camera or the coverage of the sensor [2]. More robust detection methods are being exploredto find solutions that are not dependent on the wildfire being within the field of view.The positions of the four sky polarization neutral points (points of unexpected random polariza-tion) are changed by the presence of aerosols (e.g. smoke, dust) anywhere within the sky dome [3,4, 5, 6]. So, monitoring their positions offers a promising tool for wildfire detection [1, 7]. However,more studies are needed to test the validity of this prospect. This comprehensive exam explicatesthe fundamental optical physics principles of sky polarization neutral points and then showcases theoptical engineering and image science tools needed to obtain an image of the Babinet neutral point.