杨氏双缝干涉

两相干光源到接收屏上P点距离r1=(D2+(y-a/2)2)1/2, r2=(D2+(y+a/2)2)1/2,

满足相干条件的光波叠加后，对于观察屏上某一确定点，即r1、r2确定后，叠加后的光强为 式中λ为光波的波长， 、 ，令相位差φ=2π（r2-r1）/λ,

最后可得公式如下：

，

最后光强I=4I0cos2（Φ/2）。

观察相干光叠加后光强的分布.

-Young' s double slit interference two coherent light source to the point P on the receiving screen distance r1 = (D2+ (YA/2) 2) 1/2, r2 = (D2+ (y+a/2) 2) 1/2, meet coherent conditions lightwave after superposition, for a determined point on the viewing screen, i.e. R1, R2 is determined, the superimposed light intensity where λ is the wavelength of light, make the phase difference φ = 2π (R2-R1)/λ, final can be obtained using the following formula: Finally, the light intensity I = 4I0cos2 (φ/2). Observed coherent superposition of light intensity distribution.