Adding" reflection rays from the entire family planes An incident wave(wavelength n) strikes the planes “1”and“2” bab andac vertica 1◎ B with lights a and b 2○ dd Respectively. 3○ 此公式为实验证实且可解释劳厄斑点。 The path difference for rays from adjacent planes: BD+DC=2d sin e The condition of a constructive interference 2dsnO=k(k=1.2.3 This relation is called bragg's law  Adding “reflection” rays from the entire family planes A D a’ b’ BD + DC = 2d sin An incident wave (wavelength λ）strikes the planes “1” and “2 ” (k =1.2.3) AB and AC vertical with lights a’ and b’ respectively. B C The condition of a constructive interference: 2d sin = k This relation is called Bragg’s law. The path difference for rays from adjacent planes： d 1 2 h d 3 此公式为实验证实且可解释劳厄斑点