The Michelson Interferometer

	Duration: 05:22 minutes Upload Time: 06-11-30 22:00:44 User: RoadRunnerLaser :::: Favorites
Description: This is a demonstration of the sensitivity of the Michelson Interferometer for the members of the LaserCommunity forum. A Michelson Interferometer is made by splitting a laser-beam. Bounce each beam from a mirror and back into the beam-splitter to recombine those two beams. They will cause interference patterns in the resultant beam. Project this beam through a diverging lens and onto a wall or a screen to see the patterns more clearly. They are usually used for detecting very small movements or vibrations, especially during the setup of a holography bench. They will also show the instability in the frequency of a laser. This type of interferometer will register movements of less than 1 tenth of the wavelength of the light being used. In this case, I am using 532nm and should be able to detect a movement of less than 50nm. It's sensitive enough to show the vibrations from my wife in the kitchen or walking across the floor some 5 or more metres away. It will even show the tiny vibrations from a little fluffy toy dropped from only a couple of inches onto the table where the interferometer is set up. If I was to be making holograms, each time you see those fringes (the technical term for the green stripes) move, that would equate to a ruined hologram exposure. The hardest part about setting one of these up is the alignment of the co-incident beams. It's very tricky to line up the two beams so that they exit the beam-splitter together. I'm not using an optical bench, the mirrors and lens are simply stuck down with blutac and were adjusted by hand.
Comments
Grow23 ::: Favorites Pretty good little video... nice and detailed. I would suggest a better discription for the rest of youtube who miay be interested in whats going on and not be from LC. 06-11-30 22:48:42 _____________________________________________________
RoadRunnerLaser ::: Favorites Your wish is my command. I've written a more detailed description for this video which offers a slightly better explanation. 06-12-01 08:23:37 _____________________________________________________
grimm101 ::: Favorites Thats pretty damn cool 07-01-14 10:27:00 _____________________________________________________
ThomasGrillo ::: Favorites Wow! I'd thaught about doing a demo on this, but you've done a great job of demonstrating the fragility of holographic optical layouts. Thanks. 07-04-12 16:05:12 _____________________________________________________
RoadRunnerLaser ::: Favorites I'm glad you found it useful. 07-04-21 14:12:57 _____________________________________________________
najwabrennan ::: Favorites Awesome! I have an experiment with the interferometer tomorrow. So, I know what to expect and what not to do. 07-05-07 18:48:54 _____________________________________________________
_____________________________________________________
RoadRunnerLaser ::: Favorites Enjoy your experiment. Coherent light is incredibly fascinating. Don't forget to protect your eyes with suitable goggles. 07-05-07 23:03:25 _____________________________________________________
Wizard4592 ::: Favorites Nice interference pattern, didn't know it would respond to slight vibrations like that. No wonder Michelson did his experiments on a granite slab. This video should be shown in every science class, nice job. 07-06-22 16:47:18 _____________________________________________________
RoadRunnerLaser ::: Favorites I've managed to make an interferometer which was even more sensitive than this one. I may upload a video of that at some point. The one in this video may not be as sensitive as a professionally built MI because I stuck the mirrors down with blutac which absorbs vibrations to some degree. It was really put together as a test of concept. My new one was discovered by accident... More details to follow when I get the chance. Thanks for your comments. 07-06-22 20:28:54 _____________________________________________________
Wizard4592 ::: Favorites Man its been some time since my last physics class, but I keep coming back to this stuff. I'm actually thinking of doing a similar experiment at home. Can you tell me where did you get the partially silver mirror? I ebayed it but couldn't find anything. Thanks. 07-06-23 00:33:26 _____________________________________________________
RoadRunnerLaser ::: Favorites No partially silvered mirrors involved. They are 'front-surfaced mirrors'. The 'silver' is on the front of the glass rather than on the back. The reason for this is to prevent interference from the double reflections that standard mirrors will give. I found my FSMs on eBay and there's probably still plenty of them kicking about. You'll need 2 FSMs and a beam splitter. I have a third FSM to aim the interference pattern at a wall because of space constraints. 07-06-23 09:07:06 _____________________________________________________
BabyEngineer ::: Favorites I'm studying at Caltech, at one experiment that belongs to LIGO. Now I'm reading how a Michelson interferometer works as GW detector. Your video is useful 07-08-28 18:35:36 _____________________________________________________
RoadRunnerLaser ::: Favorites Yep... They use laser-based interferometry for detecting gravity waves. I really must rebuild my other interferometer design and demonstrate that. It was far more sensitive than this one. I only had to shift my weight from one leg to the other whilst in the same room and it registered !!! I happened across this other design by accident. Darn it... Time to fire up one of my beasties and get my video camera... Watch this space ! I'm glad you found my video useful, by the way. 07-08-28 19:04:45 _____________________________________________________