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Entry  Sat Apr 24 15:05:41 2010, Kevin, Update, PSL, 2W Vertical Beam Profile vbp.jpg
    Reply  Sat Apr 24 15:50:47 2010, Koji, Update, PSL, re: 2W Vertical Beam Profile 
       Reply  Mon Apr 26 16:51:37 2010, Kevin, Update, PSL, re: 2W Vertical Beam Profile 
          Reply  Mon Apr 26 17:34:31 2010, Koji, Update, PSL, re: 2W Vertical Beam Profile 
             Reply  Tue Apr 27 15:29:16 2010, Kevin, Update, PSL, re: 2W Vertical Beam Profile vbp.jpgvbp_residuals.jpg
                Reply  Wed Apr 28 14:22:36 2010, Kevin, Update, PSL, re: 2W Vertical Beam Profile BeamFit.nb.tar
Message ID: 2846     Entry time: Mon Apr 26 16:51:37 2010     In reply to: 2838     Reply to this: 2847
Author: Kevin 
Type: Update 
Category: PSL 
Subject: re: 2W Vertical Beam Profile 

I tried Koji's suggestions for improving the fit to the vertical beam profile; however, I could not improve the uncertainties in the fit parameters.

I started retaking the data today with the same laser settings used last time and noticed that the photodiode was saturating. We were using an ND 4.0 neutral density filter on the photodiode. Koji and I noticed that the coating on the filter was reduced in the center and added an additional ND 0.6 filter to the photodiode. This seemed to fix the photodiode saturation.

I think that the photodiode was also saturating to a lesser extent when I took the last set of data. I will take another vertical beam profile tomorrow.

[Edit by KA: Metallic coating started being evaporated and the ND filters reduced their attenuation. We decided to use absorptive one as the first incident filter, and put a thinner one behind. This looked fine.]

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