[填空题]
A laser beam is directel p8 7o l,k4,qkuy7irjpe(qj u.;3gxybx)bg8 d at the Moon, 380,000 km from Earth. The beam diverges at pxgjgub)yxq 8(be; .3an angle $\theta$ (Fig. 8–37) of $1.4\times10^{-5}$ rad What diameter spot will it make on the Moon? m
Post time 2025-2-18 20:00:22
