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Entry  Thu Jul 24 17:11:18 2014, Evan, DailyProgress, optic, Calibration for scattered light measurement power.pdfccdCal.pdf10.pdf
    Reply  Fri Jul 25 08:12:40 2014, Evan, DailyProgress, optic, Calibration for scattered light measurement ccdCal.pdf
       Reply  Fri Jul 25 14:21:34 2014, Evan, DailyProgress, optic, Calibration for scattered light measurement cal.pdf
Message ID: 1459     Entry time: Fri Jul 25 14:21:34 2014     In reply to: 1458
Author: Evan 
Type: DailyProgress 
Category: optic 
Subject: Calibration for scattered light measurement 

Quote:

 Do we need to improve this before moving on to the AlGaAs BRDF measurement?

Yes.

We added an OD1.5, an OD3.0, and an RG1000 in front of the camera lens (note that these ODs are probably specked for something other than 1064 nm). Then we increased the exposure time to 20 ms. For the AlGaAs measurement, we may need to increase it even further in order to get good statistics.

Then we fixed the boom at 25° and varied the power using the upstream HWP + PBS combo.

For each power level, we took a measurement with the power meter, then 10 CCD images, then another measurement with the power meter. From this we are able to extract nominal values and uncertanties for the power level and the counts. The result is attached. The calibration has about a 4% uncertainty.

 

Note (Tara): The power measurement includes the solid angle of 3.375 x10^-3 str ( detector diameter = 0.4 inch, distance from the sample = 15.5 cm)

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