Risk Assessment Method for Back-Reflections from Space Debris in High-Power Laser Ranging

A versatile method to assess the risk arising from pulsed laser radiation reflected from space debris is presented which is based on the thresholds of maximum permissible exposure (MPE) to laser irradiation as they apply by European legislation. Gaussian beam propagation is employed considering atmospheric attenuation and turbulence-induced beam broadening. For the reflected beam specular reflection is considered as a worst-case estimate, comprising effects of target outshining and diffraction. System-specific risk charts are derived to assess the amount by which the MPE value might be exceeded for downlink reflections. These charts are directly connected to the orbital and rotational motion of the debris object via the resulting glint motion and size which is determined by the overpass geometry