Background illumination in the guidance system for laser communication on the Impulse-1 satellite

Satellite laser communication requires high-precision mutual pointing between the satellite and the ground station, which is achieved by detecting a beacon laser on a tracking camera and adjusting the optical axis. Here we research the detection procedure of the laser beacon by onboard satellite camera, focusing on the relationship between laser power, beam divergence, and background illumination influenced by seasonal and geographical factors. Considering a test image from the «Impulse-1» spacecraft, we demonstrate that a 3W laser with a 3 mrad beam divergence illumination can exceed background levels by up to 20 times, improving detection as the satellite rises above the horizon, especially when positioned directly overhead.