1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Difference between Optical and Geometrical length?

  1. Oct 1, 2013 #1
    Difference between Optical and Geometrical length!?

    I'm having this question since 2 times now in the theoretical part of the exam & still I couldn't find anything about it in the book neither in google.
    Can anyone who's more experienced in Optical Physics give me the answer to this plz !?
  2. jcsd
  3. Oct 1, 2013 #2


    User Avatar
    Science Advisor
    Gold Member

    Optical path length depends upon the index of refraction encountered; it is the same as geometrical length when the index of refraction is everywhere equal to 1.

    See http://en.wikipedia.org/wiki/Optical_path_length

    Optical path length is often used as the difference between two optical paths: then the difference in optical path length - this is used to calculate the phase shift between coherent light sources travelling the two paths, as in an interferometer.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook