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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: 2837     Entry time: Sat Apr 24 15:05:41 2010     Reply to this: 2838
Author: Kevin 
Type: Update 
Category: PSL 
Subject: 2W Vertical Beam Profile 

The vertical beam profile of the Innolight 2W laser was measured at eight points along the axis of the laser.

These measurements were made with the laser crystal temperature at 25.04°C and the injection current at 2.091A. z is the distance from the razor blade to the flat black face of the front of the laser.

The voltage from a photodiode was measured for the razor at a number of heights. Except for the first two points, one scan was made with the razor moving down and a second scan was made with the razor moving up. This data was fit to

y = a*erf(sqrt(2)*(x-x0)/w) + b with the following results:

z(cm) (±0.1cm) w(mm) chi^2/ndf
3.9 0.085 ± 0.006 77.09
6.4 0.130 ± 0.004 12.93
8.8 down 0.145 ± 0.008 66.57
8.8 up 0.147 ± 0.008 18.47
11.6 down 0.194 ± 0.010 64.16
11,6 up 0.214 ± 0.009 27.23
14.2 down 0.177 ± 0.008 49.95
14.2 up 0.183 ± 0.007 29.85
16.6 down 0.205 ± 0.006 18.35
16.2 up 0.203 ± 0.007 17.16
19.2 down 0.225 ± 0.007 18.92
19.2 up 0.238 ± 0.011 25.56
21.7 down 0.292 ± 0.006 11.30
21.7 up 0.307 ± 0.008 11.85

The values for w and its uncertainty were estimated with a weighted average between the two scans for the last six points and all eight points were fit to

w = w0*sqrt(1+(z-z0)2/zR2) with the following results:

chi^2/ndf = 17.88

w0 = (0.07 ± 0.13) mm

z0 = (-27 ± 121) mm

zR = (65 ± 93) mm

It looks like all of the data points were made in the linear region so it is hard to estimate these parameters with reasonable uncertainty.

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