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Message ID: 1520     Entry time: Mon Sep 15 18:36:32 2014
Author: tara 
Type: Notes 
Category: Vacuum 
Subject: transmission of vacuum windows 

 We measured the transmission of the vacuum windows. The total transmission through two windows is 0.975 +/- 0.002.

 

  •   This measurement is for checking how much the power is transmitted through the vacuum windows. It can be used for calibration of photo thermal measurement for better accuracy of absorption estimation.
  •  The beam is incident normal to the two windows. The power before the vac tank and after the vac tank were measured. The incident level was set ~ 4 mW. I used a Thorlab power meter with ND filter off to measured the power.
  •  
  Pin [mW] Pout [mW]
1 3.9 +/- 0.02 3.81+/- 0.02
2 3.96 3.87
3 3.98 3.88
4 3.99 3.88
  Tavg 0.975

 

If we assume that both windows have the same transmission, the transmission for each window will be 0.988.

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