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Entry  Fri Jan 23 10:00:21 2009, steve, Update, PSL, PMC transmission is down pmc4d.jpg
    Reply  Fri Jan 23 14:00:02 2009, Yoichi, Update, PSL, PMC transmission is down LaserPower.png
Message ID: 1250     Entry time: Fri Jan 23 14:00:02 2009     In reply to: 1248
Author: Yoichi 
Type: Update 
Category: PSL 
Subject: PMC transmission is down 

Quote:
The PMC transmission is going down.
I have not relocked the PMC yet.


I tweaked the alignment to the PMC.
The transmission got back to 2.65. But it is still not as good as it was 3 days ago (more than 3).

It is interesting that the PMC transmission is inversely proportional to the NPRO output.
My theory is that the increased NPRO power changed the heat distribution inside the power amplifier.
Thus the output mode shape changed and the coupling into the PMC got worse.
MOPA output shows a peak around Jan-21, whereas the NPRO power was still climbing up.
This could also be caused by the thermal lensing decreasing the amplification efficiency.
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