Measuring Coherence Length

First posting: Thu, Jan 11, 01 06:50:51 PM

Colin Kaminski

How can I measure the coherence length of a laser beam?

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Colin - Tue, Feb 13, 01 10:23:11 AM
OK this is what I have found out. To measure coherence length you build an interferometer with equal path lengths. Then you start lengthing one leg until you can no longer get any fringes. Then you shorten the leg until you get your fringes back. The difference between the path lengths is the coherence length of your laser. If you take the path difference in your split beam holography set up and subtract it from your coherence length you get the maximum depth of field you can image in ideal conditions. 206.81.100.122

A.R.Rao - Wed, Nov 28, 01 04:06:20 AM
Yes, coherence length of a laser can be measured using Michelson Interferometer. I built a simple Michelson type interferometer and varied one of the arms of the interferometr untill no fringes are observed. 202.9.184.147


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