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!

Question on beamsplitter when light is backward-incident

  1. Sep 26, 2015 #1
    Hi all,

    I'm new to this forum and not sure if this is the right place to post this question.

    I know that beamsplitters normally have dielectric coating on one side and AR coating on the other side. I'm looking at this plate beamsplitter specifically: https://www.thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=4808

    I want to know what would happen if light is incident inversely, eg, it hits AR coating first then the dielectric coating. Will I get part of the light going downwards and the rest going through the beamsplitter?

    Basically I'm looking for a beamsplitter that only allows on-way transmission.

    Any help is greatly appreciated!
  2. jcsd
  3. Sep 27, 2015 #2


    User Avatar
    2017 Award

    Staff: Mentor

    One-way transmission violates the second law of thermodynamics, it would allow to reduce entropy. I don't know how this beamsplitter would behave, but there is no one-way-transmission (neglecting exotic non-linear effects that are not relevant here).
  4. Sep 27, 2015 #3


    User Avatar
    Gold Member

    It will work the same both ways around. There are no one-way mirrors.
  5. Sep 28, 2015 #4

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor

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