40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  PSL  Not logged in ELOG logo
Entry  Thu Feb 13 16:35:32 2020, anchal, DailyProgress, BEAT, BN Detector was saturated. Reduced laser powers. 
    Reply  Fri Feb 14 10:59:13 2020, anchal, DailyProgress, BEAT, Beatnote noise lowered in low frequency region 
       Reply  Mon Feb 17 16:08:23 2020, anchal, DailyProgress, BEAT, Beatnote noise lowered in low frequency region with ISS CTN_Noise_Budget_Effect_ISS_ON.pdf
          Reply  Fri Feb 21 16:22:04 2020, anchal, DailyProgress, BEAT, Beatnote noise lowered in low frequency region with ISS CTN_Noise_Budget_Effect_ISS_ON_New.pdf
             Reply  Tue Mar 3 10:02:12 2020, anchal, DailyProgress, BEAT, Lowest ever beatnote spectrum today! CTN_Noise_Budget_March03-2020.pdf
                Reply  Thu Mar 12 11:06:35 2020, anchal, DailyProgress, BEAT, Lowest ever beatnote spectrum today! CTN_Noise_Budget_March11-2020.pdf
                   Reply  Wed Mar 18 12:51:22 2020, anchal, DailyProgress, BEAT, Super beatnote measurement analysis results CTN_Beatnote_SuperMeasurement_March13-16.pdf
                      Reply  Mon Apr 13 16:52:30 2020, anchal, DailyProgress, BEAT, Beatnote measurements back on track CTN_Latest_BN_Spec.pdf
Message ID: 2532     Entry time: Thu Feb 13 16:35:32 2020     Reply to this: 2535
Author: anchal 
Type: DailyProgress 
Category: BEAT 
Subject: BN Detector was saturated. Reduced laser powers. 

I found that the beatnote detector was actually saturating and the output was not a good pure sinewave. I've reduced the laser powers reaching the intensity to avoid that so that 20 dB coupled output of beatnote remains around 200 mVpkpk. Following is the summary of changed settings:

  North South
Before locking reflected power (mW) 4.97 5.92
After locking reflected power (mW) 1.32 0.96
After locking transmitted power (mW) 2.96 3.38
After locking total accountable power (mW) 4.28 4.34
Estimated power loss (mW) 0.69 1.58

However, the beatnote did not change because of these changes showing that moku is strictly sensitive to zero crossings of the acquired signal rather than its shape near the edges.

ELOG V3.1.3-