[填空题]
A laser beam passes through a slit oec*/u6a (hvr g ;e7* ;qqbhxepf wizu1,yq i9j hnf r:-oztm1tl *8dth 1.0 cm and is pointed at the Moon, which is approximately 380,000 km from the Earth. Assu1,q: yzo 8ftuz jim1-l*ntrh9me the laser emits waves of wavelength 630 nm (the red light of a He-Ne laser). Estimate the width of the beam when it reaches the Moon. km
