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Entry  Sat Dec 8 04:12:38 2012, Den, Update, LSC, prcl IMG_0118.JPG
    Reply  Sun Dec 9 01:21:51 2012, Den, Update, LSC, beam inside DRMI is clipping on PR3 Tip-Tilt 6x
       Reply  Sun Dec 9 17:51:53 2012, rana, Update, LSC, beam inside DRMI is clipping on PR3 Tip-Tilt 
          Reply  Mon Dec 10 03:02:03 2012, Den, Update, LSC, beam inside DRMI is clipping on PR3 Tip-Tilt PRCL_LOCK.png
             Reply  Mon Dec 10 10:13:41 2012, Den, Update, LSC, beam inside DRMI is clipping on PR3 Tip-Tilt 
                Reply  Mon Dec 10 22:34:34 2012, Den, Update, LSC, beam inside DRMI is clipping on PR3 Tip-Tilt PR2.bmpPRM_LOCK.bmpITMY.pngITMX.png
                   Reply  Thu Dec 13 03:20:48 2012, Den, Update, LSC, beam inside DRMI is clipping on PR3 Tip-Tilt PR2_ITMX.pngPR2_ITMY.pngPR3_LOCK.png
Message ID: 7801     Entry time: Sun Dec 9 01:21:51 2012     In reply to: 7800     Reply to this: 7802
Author: Den 
Type: Update 
Category: LSC 
Subject: beam inside DRMI is clipping on PR3 Tip-Tilt 

Quote:

 Today I wanted to check that AS and REFL beams are real and contain proper information about interferometer. For this I locked YARM using AS55_I and REFL11_I. Then I compared spectrum with POY11_I locking. Everything is the same. I've also adjusted phase rotations of AS55 (0.2 ->24) and REFL11 (-34.150 -> -43).

 I studied more carefully beam path inside DRMI using PRM face camera and found that beam is clipping on PR3 edge.

Step 1: PRCL LOCK, MICH LOCK, power build up 30.

Note: left is right and vice versa on the PRM camera

prcl_lock.mjpg

 Step 2: PRLC - UNLOCK, MICH - LOCK, PRM is still aligned. Right photo is AS port. I've slightly misaligned ITMs such that disturbance of AS beam is clearly seen.

PRM_UNLOCK.bmp       AS_UNLOCK.bmp

 

Step 3: PRCL - UNLOCK, MICH - LOCK, PRM misalined in yaw such such that the beam LASER -> PRM -> PR2 -> PR3 -> BS -> ITMX -> BS -> PR3 -> PR2 -> PRM -> PR2 -> PR3 is completely clipped on the TT edge. AS beam is now not clipped.

PRM_MISALIGN.bmp    AS_MISALIGN.bmp

So the conclusion is that when PRC is not locked and beam is thin, it can avoid clipping. When PRC locked, beam size grows and it starts to clip. I think we need to move the mount next to PR3 because of it we to not have enough space to align the TT.

Step 4: PSL shutter is closed.

PRM_BLOCK.bmp

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