http://commons.wikimedia.org/wiki/File:Two_Slit_Interference,_800nm_wl,_0.1mm_d,_distant_average.png

http://upload.wikimedia.org/wikipedia/commons/0/0c/Two_Slit_Interference%2C_800nm_wl%2C_0.1mm_d%2C_close_up_average.png