Algorithm for detecting airborne objects with a thermal infrared camera to ensure a safe operation of laser-optical ground stations

Laser-optical ground stations play an important role for satellite laser communication and satellite laser ranging (SLR). The safe operation of lasers in public airspace, which usually requires approval by legal entities, requires reliable, redundant, and independent systems for airborne object detection to avoid a potentially hazardous laser exposition. In this work, we propose an algorithm based on classical image filtering and thresholding to detect aircraft in images taken with a thermal infrared camera. The algorithm is optimized and evaluated with an image dataset acquired by the infrared camera mounted to SLR station miniSLR located in Stuttgart, Germany. Despite its simplicity and efficiency (7 ms for an image with 640×512 pixels on a standard consumer PCU), we find that the proposed algorithm has a high accuracy, yielding a 99.8% correct classification of images. Although laser safety systems require several independent aircraft detection methods, the proposed algorithm might be a valuable contribution for companies and institutes with the need to operate lasers in public airspace.