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Entry  Tue Apr 24 14:37:39 2018, Anchal and Andrew, DailyProgress, BEAT, Beam Profiling Beatnote detector BeamradiusProfile.pngBeam_Profile_Beatnote_-_Sheet1.csvfitatz500.png
    Reply  Wed Apr 25 12:25:09 2018, awade, DailyProgress, BEAT, Beam Profiling Beatnote detector 
       Reply  Thu May 3 22:05:23 2018, awade and anchal, DailyProgress, BEAT, Beam Profiling Beatnote detector 20180503_193329.jpg
          Reply  Wed May 9 00:51:45 2018, anchal, DailyProgress, BEAT, Beam Profiling Beatnote detector FitGraphs.pdf
             Reply  Wed May 9 08:56:54 2018, Neo, DailyProgress, BEAT, Beam Profiling Beatnote detector 
                Reply  Thu May 10 18:18:06 2018, Anchal, DailyProgress, BEAT, Beam Profiling Beatnote detector ModifiedFitWithNewData.pdfDataAndCode.zip
Message ID: 2178     Entry time: Wed Apr 25 12:25:09 2018     In reply to: 2177     Reply to this: 2179
Author: awade 
Type: DailyProgress 
Category: BEAT 
Subject: Beam Profiling Beatnote detector 

Please don't post plots in png, vector graphics only, preferably pdf with the correct transparency in the background. Here a note on plotting that summarizes some common sins: ATF:2137 

Also SI units only.  Sometimes technical drawings and other commercial technical documents and quotes are in limey units but we don't use them in the lab.

I can't really tell what is going on because of the weird units, but it looks like there isn't enough propagation distance for any meaningful change in the beam size.  

You can make a prediction of the expected beam waist size from the cavity waist (~180 µm) and by measuring the beam propagation path and taking into account the lens at output of the vacuum can. By propagating the Gaussian beam through the lens and along the beam path of the beat setup on the output you can make some predicted beam radius to compare to your measurements (in SI units, of course).  

 

 

Quote:

Today, we did the beam profiling for the beatnote detector just before the photodiode. I have attached the data taken. The z values mentioned are from a point which is 2.1 inch away from a marked line on the stage.

However, the analysis concludes that either the beam radius changes too slowly to be profiled properly with given method of measurement or something else is wrong. Attaching the the z vs w(z) plot from this data and few fit plots.

 

 

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