Optical spectrum selection for aerial target detection under complex backgrounds

It is of strong practical significance to the management of civil aviation aircrafts through optical detection of aerial targets. A proper detection spectrum can help to enhance the target and suppress the background, guaranteeing the real-time accurate positioning and tracking of aerial targets over a wide range. Firstly, the principle of space-based air target detection is introduced. By analyzing the sources of the target radiation and background radiation, the contrast between target and background radiation intensity is determined as the evaluation standard for space-based detection. In simulations, three typical backgrounds (sea, farm and desert) and Boeing 737 aircraft were taken as examples. The apparent spectral radiance of the background in each spectral band was analyzed with the bulk and apparent spectral radiance of the aerial target under different detection conditions (detection azimuth angle, elevation angle, flight height). By traversing the 2~6 μm spectral range with a maximum spectral width of 1 μm, the contrast between target and background radiation intensity was calculated. 29 alternative spectral bands under 30 working conditions, including different flight altitudes, different backgrounds and different detection azimuth angels, were screened for the contrast between target and background radiation intensity exceeding the threshold of 2000. Considering changes in the upper and lower limit values of the contrast between the target and the background radiation intensity under each spectrum, background, target flight altitude and detection azimuth angle, the 2.53~2.54 μm spectrum could be used as one of the preferred spectral bands of the space-based aerial target optical detection system.