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Entry  Sun Jul 1 23:48:15 2012, yuta, Summary, General, clipping at BS, my plan PR3.JPGPRM.JPG
    Reply  Mon Jul 2 00:41:13 2012, rana, Summary, General, clipping at BS, my plan 
    Reply  Mon Jul 2 10:45:25 2012, Jenne, Summary, General, clipping at BS 
Message ID: 6900     Entry time: Sun Jul 1 23:48:15 2012     Reply to this: 6901   6902
Author: yuta 
Type: Summary 
Category: General 
Subject: clipping at BS, my plan 

[Koji, Yuta]

We aligned PRMI and inspected BS chamber. Last inspection by Jamie and I (see elog #6897) was done when nothing is aligned, so I wanted to see the difference.
Aligning PRMI at low power was difficult for me, because I see no fringe at ASDC PD nor REFLDC PD. I just aligned them by looking at AS/REFL camera. The beam shape at AS looked as bad as when the usual power.

No significant change was found inside the vacuum. We still see clipping at the Faraday, and also, we saw clipping by BS coil holder. Using PZT1, we could make it better, but this might be causing PRC problem -- BS is inside the PRC, too.

We also took some pictures of PR3 and PRM(attached). The arrow pointing HR is correctly pointing inside the PRC. Seeing is believing.

Yuta's plan:
  We might have to avoid clipping at BS (and Faraday) by aligning input optics inside the vacuum. If we are going to align them, I think we should start from centering MC beam spot positions and the whole alignment could take more than a week. I don't want to spend too much time on the alignment. Also, we are going to install tip-tilts on the next big vent, so we have to redo the alignment anyway.
  So, my plan is as follows;

1. Take lots of photos and close the door on Monday(June 2).

2. Pump on Tuesday(June 3).

3. Restart working on ALS. For example, demonstration of FPMI using ALS.

4. We also can do some characterization of PRC, like measuring power recycling gain for PRMI/PRFPMI, mode scan for PRC using AUX laser from AS port, and so on. We need some calculation for clipping tolerance, too.

  Any objections?

Attachment 1: PR3.JPG  3.154 MB  | Hide | Hide all
Attachment 2: PRM.JPG  2.362 MB  | Hide | Hide all
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