S AB= BC 反射光2反射光1 COS y DC=ACSin i=2dtgr sin i n,sin=n, sin y d=2n, AB n, DC+d 2 2 n2 2dtgr.n,sin r+ y nI =2n2(1 coSy = 2n,d cos y 2 加强 δ=2d√n2-n2sn2+= 2(2k+1) λ减弱 k=0,±1,±2 当n1>n2同理cos d AB = BC = DC = ACsin i = 2dtg sin i sin sin  1 n2 n i = 2 2 2 1   = n AB − n DC + 2 2 sin cos 2 2 2     = − dtg n + d n 2 (1 sin ) cos 2 2 2    = − + d n 2 2 cos 2  = n d  +     + = − + = 减弱 加强 2 2 (2 1) 2 sin 2 2 1 2 2     k k d n n i k = 0,1,2.... 当n1  n2同理 反射光2 反射光1 S 1 2 n2 d  A B n1 n1 i D · C