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Entry  Sat Nov 6 07:26:54 2010, yuta, Summary, IOO, reduced common mode displacement of the beam through MC1 to MC3 A2LMCalign.png
    Reply  Tue Nov 9 05:40:12 2010, yuta, Summary, IOO, MC aligning going on MCalignNov9.png
       Reply  Wed Nov 10 02:51:35 2010, yuta, Summary, IOO, limitation of current MC aligning MCalignNov9.png
          Reply  Wed Nov 10 11:46:19 2010, Koji, Summary, IOO, limitation of current MC aligning 
             Reply  Wed Nov 10 12:21:18 2010, yuta, Summary, IOO, limitation of current MC aligning 
                Reply  Wed Nov 10 14:28:33 2010, Koji, Summary, IOO, limitation of current MC aligning 
Message ID: 3883     Entry time: Tue Nov 9 05:40:12 2010     In reply to: 3876     Reply to this: 3884
Author: yuta 
Type: Summary 
Category: IOO 
Subject: MC aligning going on 

(Suresh, Yuta)

Background:
  Last week, we reduced the common mode displacement of the beam through MC1 to MC3. 
  Next work is to tilt the beam and center it.

What we did:
  1. Changed the offset going into 1201 Low Noise Amplifier(1201 is for adding +5V offset so that the feedback signal will be in the range of 0-10V)
  2. Using the last steering mirror(SM@PSL) and IM1, tilted the beam
  3. As the beam height changed alot(~0.5cm higher at IM1), MC1 reflection could not reach MCREFL PD. So, we tilted the mirror just after MC1, too.

Result:
MCalignNov9.png

Plan:

  - continue to tilt IM1 in small increments in order to reduce PIT/YAW to length coupling
      If large increments, it takes so much time re-aligning MC to get flashing!

By the way:

    The signal we kept saying "MCL" was not the error signal itself. It was a feed back signal(output of the mode cleaner servo board). The cable labeled "MC REFL" is the error signal. Compare MEDM screen C1IOO_MC_SERVO.adl and the mode cleaner servo board at 1X2. You will be enlightened.

Quote (from elog #3857):

4. Disconnected the cable labeled "MC OUT1" at 1X2 (which is MCL signal to ADC) and put MC2_ULCOIL output directly using long BNC cable.

 

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