In developing High Energy Laser (HEL) weapons, it is necessary to understand the absolute radiometry associated with propagating the beam to the target. This is important for setting filter attenuation levels for the tracker, laser beacons, and battle damage assessment sensors, along with more traditional calculations of laser fluence on the target. In this paper, we will present the theory and experimental validation for laser beams propagating over large distances through atmospheric turbulence. We conducted several experiments at Starfire Optical Range (SOR) in Albuquerque during 1997 to prove that we can accurately predict the uplink irradiance, the target signature, and the power levels or signal received from laser propagation. Specifically, using the Lageos satellite, we were able to predict the absolute signal to within 20% of the measured values. Subsequent experiments verify that the models we developed continue to accurately predict the absolute radiometry associated with laser beam propagation. The results should be useful for laser sensing, modeling and simulation, and exploitation and target recognition.