To obviate the problems associated with targeting incoming missiles, the U.S. Air Force has chosen to develop a weapon capable of downing missiles soon after launch. It would involve a high-power laser installed on a specially equipped jumbo jet that would detect and track a missile seconds after launch, using the heat of a laser strike to drop the climbing missile on enemy territory. We have, therefore, studied the widening of laser-radar beam pulses sent vertically into the atmosphere and reflected back to earth. We can also measure turbulence directly from the 'dancing' of the position of return of our laser-radar beam. The BGU researchers found that turbulence strength is greater than what had been assumed previously.
Investigators generally determine turbulence indirectly via temperature measurements.
Since the Kopeika group uses light, it can measure total turbulence, which includes the effects of humidity and aerosols, as well as temperature. The investigators also measured the direct effect of aerosols on laser-beam widening and found that these effects are often more significant than those of turbulence. For positioning the flying platform carrying ABL weapons, operators should know the most effective altitude for laser activation, namely the height above cloud cover that would result in minimum beam widening. This determination would require a mathematical model able to predict beam widening. Designing such a model, which is now under development at BGU, would involve knowledge of surface weather and the properties of the aerosol layers at various elevations, as well as how these change with seasons, times of day, geographical locale, high-altitude winds, and cloud layers.