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Entry  Thu Jul 17 02:57:32 2014, Andres, Update, 40m Xend Table upgrade, FInish Calculation on Current X-arm mode Matching RawDataForTheModeGreenScan.pngResultForModeMatching.pngDataAndCalculationOfModeMismatch.zip
    Reply  Fri Jul 18 16:52:56 2014, Andres, Update, 40m Xend Table upgrade, FInish Calculation on Current X-arm mode Matching OldAndNewSetupPlotsOfDisplacementAndAngleAtTheETM.pngOldSetUpDisplacementAndNewSetup.m.zip
Message ID: 10226     Entry time: Thu Jul 17 02:57:32 2014     Reply to this: 10237
Author: Andres 
Type: Update 
Category: 40m Xend Table upgrade 
Subject: FInish Calculation on Current X-arm mode Matching 

Data and Calculation for the Xarm Current Mode Matching

Two days ago, Nick, Jenne, and I took a measurement for the Green Transmission for the X-arm. I took the data and I analyzed it. The first figure attached below is the raw data plotted. I used the function findpeaks in Matlab, and I found all the peaks. Then, by taking close look at the plot, I chose two peaks as shown in the second figure attached below. I took the ratio of the TEM00 and the High order mode, and I average them. This gave me a Mode Matching of 0.9215, which this value is pretty close to the value that I predicted by using a la Mode in http://nodus.ligo.caltech.edu:8080/40m/10191, which is 0.9343. Nick and I measured the reflected power when the cavity is unlocked and when the cavity is locked, so we measured the PreflUnLocked=52+1µW and PreflOnLocked=16+2µW and the backgroundNoise=0.761µW. Using this information we calculated  Prefl/Pin=0.297. Now, since Prefl/Pin=|Eref/Ein|2, we looked at the electric fields component by using the reflectivity of the mirror we calculated 0.67. The number doesn't agree, but this is because we didn't take into account the losses when making this calculation. I'm working in the calculation that will include the losses.

Today, Nick and I ordered the lenses and the mirrors. I'm working in putting together a representation of how much improvement the new design will give us in comparison to the current setup.

Attachment 1: RawDataForTheModeGreenScan.png  15 kB  | Hide | Hide all
Attachment 2: ResultForModeMatching.png  18 kB  | Hide | Hide all
Attachment 3: DataAndCalculationOfModeMismatch.zip  1.408 MB
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