The discussion centers on the conditions necessary for observable wave interference, specifically the relationship between path difference and coherence length. It is established that the path difference must be smaller than the coherence length to achieve significant interference. This is due to the requirement for overlapping light to maintain a fixed phase relationship, which diminishes when the path difference exceeds the coherence length. The analogy of two individuals on a ski lift illustrates how varying distances can disrupt phase alignment.
PREREQUISITESStudents and educators in physics, optical engineers, and anyone interested in the principles of wave behavior and interference patterns.
You'll only get significant interference when the overlapping light is coherent (which means that it has some fixed, non-random phase relationship). So, if the path difference is more than the coherence length, there won't be enough coherence to produce a good pattern.oupi said:for condtion of observable interference, why do the path difference should be smaller than the coherent length ??