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 Tue Jul 14 00:57:11 2009, Alberto, Update, Locking, photodiode alignment check
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 Wed Jul 15 12:14:08 2009, Alberto, Update, Locking, photodiode alignment check 
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Thu Jul 16 01:00:56 2009, Alberto, Update, Locking, PD9 aligned
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Message ID: 1749
Entry time: Wed Jul 15 12:14:08 2009
In reply to: 1742
Reply to this: 1755
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| Author: |
Alberto |
| Type: |
Update |
| Category: |
Locking |
| Subject: |
photodiode alignment check |
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| Quote: |
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Since lately the alignment of the input beam to the interferometer has changed, I went checking the alignment of the beam on the photodiodea. They were all fine except for pd9, that is AS DD 199. Here the DC is totally null. The beam seems to go right on the diode but the scope on the PD's DC output shows no power. This is really strange and bad.
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After inspecting PD9 with the viewer and the cards, the beam looks like it is aligned to the photodiode althought there is no signal at the DC output of the photodetector. So I checked the spectrum for PD9_i and Q (see attachments) and it seems that those channels are actually seeing the beam. I'm going to check the alignemtn again and see the efefct on the spectra to make sure that the beam is really hitting the PD.
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