Suppose that a TEM00 gaussian beam from a ruby laser ( 694.3 nm) is transmitted through a  1-m diameter diffraction limited telescope to illuminate a spot on the surface of the moon. Assume an earth-moon distance 348000 km and using the relation between the telescope objective diameter and beam spot size ,  D = 2.25 W0 ,  calculate the beam spot size on the moon. (diffraction effects from the atmosphere can be important, but they are neglected here).