DIY Laser Interferometer (an Introduction To Interferometry)
    By Steve Schuler | September 6th 2013 06:01 PM | 2 comments | Print | E-mail | Track Comments
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    This is a simple build of a Michelson Interferometer using the SpyNet Laser Tripwire . About a year ago, I accidentally came across this toy and noticed that it has a red laser and two adjustable mirrors. It also has a receiver that will sound an alarm when the laser beam that shines on it is blocked. Yes, I have reverse engineered the receiver—a rather simple circuit, really—and, of course, improved it and may post an article about it to demonstrate an SCR (Silicon-Controlled Rectifier). I requested a reviewer’s sample from Jakks Pacific but did not receive one, so I had to wait for an after Christmas sale and found a set for 80% off (about $5.00 USD which was less than purchasing a laser pointer and two makeup mirrors). Remember, do not shine the laser beam into your eyes, nor anyone else's.

    Parts needs from the Laser Tripwire set:


    2 Adjustable mirrors

    Additional Parts:

    CD clamshell

    Cardboard backing from a 8 ½ X 11 notepad

    Sheet of blank white printer paper 8 ½ X 11

    4 Paperclips

    Large binder clip

    A magnifying lens (mine came from my telescope)

    Something to prop the lens on (I used my copy of The Complete Works of Shakespeare)

    Here’s the layout of the interferometer:

    If you don’t have the Spynet Laser Tripwire set you can replace the parts with a cat toy (laser pointer) and two makeup mirrors. Here’s an excellent video by Celtic Mad Scientist that demonstrates how to build the interferometer:

    I have yet to build a receiver (out of what else? Snap Circuits!), but the laser interferometer can be used for quite a number of physics demonstrations from wave/particle duality to (and don’t hold me to this because it has proved to be quite a challenge) a P-wave detector, or earthquake early warning device. 


    Laser ring gyro, if you can make an Interferometer..........
    Never is a long time.
    Maybe...still trying to work out a good receiver. Anyway, currently working on article for FM and PPM.
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