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