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Laser Interferometer - Inexpensive & Homemade

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I'd like to share one of my latest experiments, a laser interferometer that I made at home with about $20 of parts (well, I used a green laser, but a red can work too). Of course, I had two mirrors, a lens to magnify the interference fringes, but how did I really save money? I used a 10 cent CD jewel case for a beam splitter!


Even with this hacking, I got some crisp fringes, and I hope to use this to test the stability of my setup when I try making holograms again.


Even though I'm only working with Class IIIa lasers, you should take care not to look into the beam or reflections. Laser goggles of a low optical density might be advisable.


Here's the link to my explanatory video:

Laser Interferometer - Homemade for $20


For those who may not be familiar with an interferometer, it's just a device that interferes waves. The beam is split in 2 and the resulting beams are projected onto a surface via the mirrors to observe interference. In this case, by interfering light waves, we could potentially measure distances and movement on the order of the wavelength of light, say 532 nm. Michelson & Morley used a device like this to measure the length of a meter accurately and also show the lack of a luminferous ether (a medium for light) thus showing that the speed of light is constant.


Hope you enjoy it. :)

Edited by CelticMadSci
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Normally each beam of the light is reflected once off of a mirror in a Michelson interferometer, but you've got one beam doing two reflections, which makes it more sensitive to vibrations. Though that may be what you want if you're testing stability for holograms.

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Wow, you're right, I have the beam splitter rotated 90 degrees. :doh:


Looking at the paths, the one that hits 2 mirrors could also make more round trips with reduced power from the beam splitter each time.


I'll have to try it the proper way and compare the sensitivity. :)

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