Homework SourseSuppose the reflection shifts put the reflected rays exactly
Suppose the reflection shifts put the reflected rays exactly out of phase and we want the rays to undergo fully constructive interference. What phase shift should be contributed by the travel of one of the rays across the width of the film and then back again?
| That travel twice through the film thickness should contribute a phase shift of 1.0 wavelength or an integer times it. |
Solution
1 full cycle is a phase change of 2 radians.
For 2 waves to be in phase requires a phase difference of 0, 2, 4, 6, ... radians (in general 2n where n is 0,1,2,3,...
Being put out of phase means the waves have a phase difference of (or 3, or 5 etc) radians.
The required extra phase shift can therefore by , 3, 5, 7, etc. In general this is (2n+1) radians. Adding this changes an odd number of \'s to an even number of \'s.
| That travel twice through the film thickness should contribute a phase shift of 1.0 wavelength or an integer times it. is true |
