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!

Young Double Slit Experiment Help

  1. Jan 19, 2012 #1
    I am trying to recreate the Young double slit experiment at my house with a laser. You could call it a homemade experiment I suppose. My question is if I use a laser pointer for my photon source what would I use as the photon detector. I want to have some sort of screen that can detect the photons as they hit the apparatus and then in return create a graph or data tale on my computer. Any ideas? I'm a junior in highschool and extremely interested in the mysterious world of quantum physics.
     
    Last edited: Jan 19, 2012
  2. jcsd
  3. Jan 20, 2012 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    You can use a normal screen for just looking at - get your experiment going with that before figuring out what sort of detector you want for your computer.

    However, if you are serious, then you can get a digital oscilloscope for your computer which you can add electronic devices to to act as detectors.
    For that matter - you can convert your sound-card mic input t act as a low V, audio frequency oscilloscope in software.
     
  4. Jan 20, 2012 #3
    Thanks! Any better ideas for my photon source? Id love to have a smaller stream of photons and it would amazing to be able to shoot individual photons
     
  5. Jan 20, 2012 #4

    Drakkith

    User Avatar

    Staff: Mentor

    Maybe two polarizers set almost 90 degrees from one another? I think that might block almost all photons from getting through. Though with single photons you'd need a near perfectly light proof container along with something to detect the photons, such as a CCD or other digital imager.
     
  6. Jan 20, 2012 #5

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2016 Award

    It is one thing to show the 2-slit interference (easy). It is a different world when you want to do this one photon at a time. The latter is not trivial.

    For example, this is a typical undergraduate experiment dealing with such a demonstration:

    http://www.teachspin.com/instruments/two_slit/index.shtml [Broken]

    Not only do you need a single photon source, you also need single-photon detector! If you use light-sensitive plates, then you now have the added complexity of need to do this in a totally dark enclosure.

    Zz.
     
    Last edited by a moderator: May 5, 2017
  7. Jan 20, 2012 #6

    Claude Bile

    User Avatar
    Science Advisor

    Welding goggles would be suitable as a high optical density filter as well.

    On detection, a scattering screen and a CCD camera with a long exposure?

    EDIT: Agree with ZapperZ; isolating the small signal from optical noise will be the biggest hurdle. Depending on photon flux, a CCD will probably need to be cooled. You can't beat a photomultiplier tube for sensitivity, but I'm guessing you don't have access to that.

    Claude.
     
    Last edited: Jan 20, 2012
  8. Jan 20, 2012 #7

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    You can go a long way with backyard physics using surplus equipment, just google for Peter Terrin.

    I think this is a case of: "how much money do you want to spend?"
     
  9. Jan 20, 2012 #8
    To be honest I'm only 17 and I have no formal education in physics. I'm simply amazed by the quantum world. Likewise, I barely comprehend many of the terms in the replies. I'm not familiar with an of the equipment you guys are talking about lol.
     
  10. Jan 20, 2012 #9
    Totally dark would be very challenging. The whole experiment may as well be performed within a dark box/container.
     
  11. Jan 20, 2012 #10

    Drakkith

    User Avatar

    Staff: Mentor

    In that case I highly recommend just using a simple laser, double slit, and project it on the wall or simple screen.

    Yep. It would need to be in a container and you would need a digital camera or other device to detect the photons.
     
  12. Jan 20, 2012 #11
    Great video thanks but the only issue with that is i must find a dim light (easy) and dark box (easy) and a very sensitive light detector (hard and expensive).
     
  13. Jan 20, 2012 #12

    Drakkith

    User Avatar

    Staff: Mentor

    I wonder if a cell phone camera could work? I barely use mine so I don't know if you can control things like shutter speed and exposure time and whatnot.
     
  14. Jan 20, 2012 #13
    A dark box and high exposure ccd sensor on a canon camera may be my best bet. As far as the single photon issue I think I have figured that out: use a very dim light source that only spits out a thousand photons a second. Sounds like a lot but light takes time to travel therefore it results in a single photon every .5 seconds.
     
  15. Jan 20, 2012 #14
    My dad has a very high tech camera that I could easily adjust the shutter speed. In fact, I've messed with the feature several times before.
     
  16. Jan 20, 2012 #15

    Drakkith

    User Avatar

    Staff: Mentor

    I think you have your math a little wrong. 1 thousand photons per second would result in 1 photon every 0.001 seconds on average. Speed would not affect this.
     
  17. Jan 20, 2012 #16
    Yah I didn't even work it out I just guessed lol. The guy in the video gave the exact number but 1 photon every .001 seconds is actually not bad. It's closer to my 1 photon at a time goal. I can set the cameras shutter speed to capture a designated number of photons now that I know the frequency.
     
  18. Jan 20, 2012 #17

    Drakkith

    User Avatar

    Staff: Mentor

    Have you considered a polarizer? Laser light should be all the same, so a single polarizer might be able to be rotated to block almost all of the light. Heck, a pair of polarizing sunglasses may work if the light is linearly polarized.
     
  19. Jan 20, 2012 #18
    What's the object of the polarizer? To make the stream of photons more concentrated? I just need help finding a dim light that would emit only 1000 photons a second
     
  20. Jan 20, 2012 #19

    Drakkith

    User Avatar

    Staff: Mentor

    See here: http://en.wikipedia.org/wiki/Polarizer

    Using a polarizer may block enough of the photons to reduce the rate to only a few photons per second. I don't know for sure if this would work in your setup, but I think it's worth a look.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Young Double Slit Experiment Help
Loading...