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Entry  Tue May 25 17:42:11 2021, Anchal, Paco, Summary, ALS, ALS Single Arm Noise Budget ALS_IR_b.svgALS_Single_Arm_IR.pdf
    Reply  Thu May 27 11:03:15 2021, Anchal, Paco, Summary, ALS, ALS Single Arm Noise Budget ALS_Single_X_Arm_IR.pdfALS_OOL_with_Ref.pdf
       Reply  Fri May 28 17:32:48 2021, Anchal, Summary, ALS, Single Arm Actuation Calibration with IR ALS Beat SingleArmActCalwithIRALSBeat.pdfstateSpaceModel.zip
          Reply  Tue Jun 1 16:55:32 2021, Anchal, Paco, Summary, ALS, Single Arm Actuation Calibration with IR ALS Beat SingleArmActCalwithIRALSBeat-1306624785.pdf
             Reply  Tue Jun 8 11:40:53 2021, Anchal, Paco, Summary, ALS, Single Arm Actuation Calibration with IR ALS Beat ITMX_Cal_Noise_Spectrum_1307143423.pdf
                Reply  Wed Jun 9 18:29:13 2021, Anchal, Paco, Summary, ALS, Check for saturation in ITMX SOS Driver 
                Reply  Fri Jul 9 15:39:08 2021, Anchal, Summary, ALS, Single Arm Actuation Calibration with IR ALS Beat [Correction] ITMX_calibration_With_ALS_Beat.pdf
Message ID: 16168     Entry time: Fri May 28 17:32:48 2021     In reply to: 16164     Reply to this: 16171
Author: Anchal 
Type: Summary 
Category: ALS 
Subject: Single Arm Actuation Calibration with IR ALS Beat 

I attempted a single arm actuation calibration using IR beatnote (in the directions of soCal idea for DARM calibration)


Measurement and Inferences:

  • I sent 4 excitation signals at C1:SUS-ITM_LSC_EXC wit 30cts at 31Hz, 200cts at 197Hz, 600cts at 619Hz and 1000cts at 1069 Hz.
  • These were sent simultaneously using compose function in python awg.
  • The XARM was locked to mai laser and alignment was optimized with ASS.
  • The Xend Green laser was locked to XARM and alignment was optimized.
    • Sidenote: GTRX is now normalized to give 1 at near maximum power.
    • Green lasers can be locked with script instead of toggling.
    • Script can be called from sitemap->ALS->! Toggle Shutters->Lock X Green
    • Script is present at scripts/ALS/lockGreen.py.
  • C1:ALS-BEATX_FINE_PHASE_OUT_HZ_DQ was measured for 60s.
  • Also, measured C1:LSC-XARM_OUT_DQ and C1:SUS-ITMX_LSC_OUT_DQ.
  • Attachment 1 shows the measured beatnote spectrum with excitations on in units of m/rtHz.
  • It also shows resdiual displacement contribution PSD of (output referred) XARM_OUT and ITMX_LSC_OUT to the same point in the state space model.
    • Note: that XARM_OUT and ITMX_LSC_OUT (excitation signal) get coherently added in reality and hence the beatnote spectrum at each excitation frequency is lower than both of them.
    • The remaining task is to figure out how to calculate the calibration constant for ITMX actuation from this information.
    • I need more time to understand the mixture of XARM_OUT and ITMX_LSC_OUT in the XARM length node in control loop.
    • Beatnote signal tells us the actual motion of the arm length, not how much ITMX would have actuated if the arm was not locked.
  • Attachment 2 has the A,B,C,D matrices for the full state space model used. These were fed to python controls package to get transfer functions from one point to another in this MIMO.
    • Note, that here I used the calibration of XARM_OUT we measured earlies in 16127.
    • On second thought, maybe I should first send excitation in ETMX_LSC_EXC. Then, I can just measure ETMX_LSC_OUT which includes XARM_OUT due to the lock and use that to get calibration of ETMX actuation directly.

Attachment 1: SingleArmActCalwithIRALSBeat.pdf  43 kB  Uploaded Fri May 28 18:39:12 2021  | Show | Show all
Attachment 2: stateSpaceModel.zip  6 kB  Uploaded Fri May 28 18:53:36 2021
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