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ID Date Authorup Type Category Subject
  11871   Thu Dec 10 19:53:22 2015 yutaroUpdateLSCstrange behavior of ASDC

To check if the strange behavior of ASDC is caused by SR2/SR3 or not, I did the following measurement:

ASDC measures the power of the light reflected by ITMX. POXDC measures the power of the light reflected by ITMX and SRM successively. Then I varied the angle of ITMX in YAW direction and compared the behaviors of ASDC and POXDC.

The results are shown in Attachments 1-3.

As you can see in these figures, the strange up-and-down behavior appeared ONLY in ASDC. Therefore, the cause of this behavior exists between AS table and SRM (I had confirmed that the angle of SRM did not affect ASDC).

And this behavior is fringe-like, as can be seen in the figures (there seems to be 3 "peaks" and 2 "valleys"), so the cause could be interference between main path and not good AR reflection at a mirror after SRM before AS table (I suspect a mirror is flipped mistakenly).   

  11872   Fri Dec 11 09:35:44 2015 yutaroUpdateLSCPower recycling gain estimation from arm loss measurement

I took PR3 AR reflectivity and calculated PRG (PR3 is flipped and so AR surface is inside PRC).

As shown in attached figure, which shows AR specification of the LaserOptik mirror (PR3 is this mirror), AR reflectivity of PR3 is ~0.5 %. Since resonant light in PRC goes through AR surface of PR3 4 times per round trip, round trip loss due to this is ~2 %. Then I got

PRG = 7.8.    


  11874   Fri Dec 11 15:37:50 2015 yutaroUpdateLSCPower recycling gain estimation from arm loss measurement

Attached is the plot of relation between the average arm round trip loss and power recycling gain. 2 % loss due to PR3 AR reflection is taken into account.

  11875   Fri Dec 11 16:16:36 2015 yutaroUpdateOptical LeversCalibration of oplevs for ITMX/ETMX

Based on calibration measurement I have done (elog 11785, 11831), I updated calibration factors of oplevs on medm screen as follows. Not to change loop gain oplev servo, I also changed oplev servo gain.


(45.1,16) => (200,3.5)


(85.6,8) => (222,3.0) 


(26,-16) => (140,-3.0) 


(31,-21) => (143,-4.5) 


(110,8) => (122,7.2) 


(81,-11) => (147,-6) 


(159,15) => (239,10) 


(174,-21) => (226,-16) 


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