Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Cavity Length of LASER and Interference

  1. Jan 27, 2005 #1
    I have been working on an experiment that uses double exposure holography to determine sub-micrometer displacements. [see attached picture for details]

    It turns out that the optical path lengths LRP and LOP do not have to be exactly but roughly equal for the light if you want the light from R at P and the light from O at P to be in phase. I have been told that the two optical path lengths LRP and LOP have to be equal to within a factor of the cavity length of the LASER in use.

    I am confused as to why you can still have LRP slightly larger or smaller than LOP and still have light at P that is in phase. Any help/insights is much appreciated.
     

    Attached Files:

  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted