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Entry  Fri Nov 1 17:54:47 2019, anchal, DailyProgress, FSS, FSS Diagnostics - RFPD RF Ouput under inspection NFSS_RFPD_Output_Oscilloscope.pdfSFSS_RFPD_Output_Oscilloscope.pdfNFSS_RFPD_RF_OUT_COUPLED.pdfSFSS_RFPD_RF_OUT_COUPLED.pdf
    Reply  Tue Nov 5 18:37:59 2019, anchal, DailyProgress, FSS, FSS Diagnostics - TTFSS Testpoint Spectrum Data FSS_TP_Spectrum.pdf
       Reply  Sat Nov 9 19:28:36 2019, anchal, DailyProgress, FSS, FSS Diagnostics - Loop nonlinearity Test NFSS_NonLinearity_Test.pngSFSS_NonLinearity_Test.pngsignal-attachment-2019-11-09-195635.jpeg
          Reply  Mon Nov 11 20:42:49 2019, anchal, DailyProgress, FSS, FSS Diagnostics - Two Tone Test NFSS_RFPD_SN009_TF_11-11-2019_183131.pdfSFSS_RFPD_SN010_TF_11-11-2019_203310.pdfFSStwoToneTest.pdf
             Reply  Tue Nov 12 18:36:59 2019, anchal, DailyProgress, FSS, FSS Diagnostics - Two Tone Third Order Intermodulation Test FSStwoToneThirdOrderIM.pdf
                Reply  Thu Nov 14 12:19:32 2019, rana, DailyProgress, FSS, FSS Diagnostics - Two Tone Third Order Intermodulation Test 
                   Reply  Tue Nov 19 18:51:02 2019, anchal, DailyProgress, FSS, FSS Diagnostics - Second-order Distortion Calculation FSSDistortionCalc.pdfFSSDistortion.zip
                      Reply  Mon Dec 9 19:54:44 2019, anchal, DailyProgress, FSS, FSS Diagnostics - How much distortion affects the functioning of PDH? 
       Reply  Wed Nov 27 13:59:24 2019, anchal, DailyProgress, FSS, FSS Diagnostics - TTFSS TP1 TimeSeries NFSS_TP1_Oscilloscope.pdf
          Reply  Wed Nov 27 15:17:51 2019, anchal, DailyProgress, FSS, FSS Diagnostics - Quick HF OLTF of NFSS NFSS_OLTF_HF.pdf
             Reply  Wed Nov 27 16:31:20 2019, rana, DailyProgress, FSS, FSS Diagnostics - Quick HF OLTF of NFSS 
                Reply  Wed Dec 4 18:11:09 2019, anchal, DailyProgress, FSS, Free running laser frequency noise spectrum PMCErrorSignals.pdf
                   Reply  Thu Dec 5 18:25:11 2019, rana, DailyProgress, FSS, Free running laser frequency noise spectrum 
                   Reply  Tue Dec 17 18:29:58 2019, anchal, DailyProgress, FSS, Need for ISS? 
                      Reply  Wed Dec 18 18:40:32 2019, anchal, DailyProgress, FSS, Maybe the NPRO Laser isn't bad after all NorthLaserRINAnalysis.pdf
                         Reply  Wed Dec 18 22:03:17 2019, rana, DailyProgress, FSS, Maybe the NPRO Laser isn't bad after all 
                            Reply  Fri Dec 20 15:00:30 2019, anchal, DailyProgress, FSS, PZT, EOM to RIN TF Measurement NorthLaserPZTEOMtoRINTF.pdf
                               Reply  Fri Dec 20 18:08:44 2019, anchal, DailyProgress, FSS, PZT, EOM to RIN TF Measurement Through FSS NorthLaserPZTEOMtoRINTFThruFSS.pdf
                                  Reply  Tue Jan 7 17:59:20 2020, anchal, DailyProgress, FSS, NPMC TF NPMC_TF.pdf
       Reply  Thu Dec 12 19:15:55 2019, anchal, DailyProgress, FSS, FSS Diagnostics - Beatnote Spectrum wrt Laser Power and Modulation Index BeatnoteSpectrumwrtPowerandModindex.pdf
       Reply  Tue Dec 17 16:55:07 2019, anchal, DailyProgress, FSS, FSS Diagnostics - TTFSS North U7 Boost Stage Input-Output TimeSeries NFSS_UT_TS_Analysis.pdf
    Reply  Tue Nov 12 11:39:48 2019, anchal, DailyProgress, FSS, FSS Diagnostics - RFPD RF Ouput under inspection 
    Reply  Fri Dec 13 16:24:02 2019, anchal, DailyProgress, FSS, FSS Diagnostics - RFPD Circuit Latest Available Photos SN009.jpgSN010.jpgSN009.jpgSN010.jpg
    Reply  Fri Dec 13 17:44:05 2019, anchal, DailyProgress, FSS, FSS Diagnostics - RFPD RF Coupled Output Offset 
       Reply  Mon Jan 13 19:04:38 2020, anchal, DailyProgress, FSS, FSS Diagnostics - SN009 (North RFPD) Notch Improvement Attempt SN009.jpgSN009_D980454-00-C.pdfSN009_Notch_Improvement_Attempt.pdf
          Reply  Tue Jan 14 18:19:33 2020, anchal, DailyProgress, FSS, FSS Diagnostics - SN009 (North RFPD) Notch Improved! SN009.jpgSN009_D980454-00-C.pdfSN009_Notch_Improvement_Attempt.pdf
             Reply  Thu Jan 16 11:17:15 2020, anchal, DailyProgress, FSS, FSS Diagnostics - SN010 (South RFPD) Notch Improvement Attempt SN010.jpgSN010_D980454-00-C.pdfSN010_Notch_Improvement_Attempt.pdf
                Reply  Thu Jan 16 20:18:44 2020, anchal, DailyProgress, FSS, FSS Diagnostics - SN010 (South RFPD) Notch Improved SN010.jpgSN010_D980454-00-C.pdfSN010_Notch_Improved.pdf
                   Reply  Mon Jan 27 18:29:19 2020, anchal, DailyProgress, FSS, FSS Diagnostics - RFPD RF Out Spectrum FSS_RFPD_RFOut_Spectrum.pdf
Message ID: 2495     Entry time: Thu Dec 12 19:15:55 2019     In reply to: 2474
Author: anchal 
Type: DailyProgress 
Category: FSS 
Subject: FSS Diagnostics - Beatnote Spectrum wrt Laser Power and Modulation Index 

I took beatnote spectrums in the current modulation index (was set to around 0.3 earlier). Then I took spectrum after attenuating the modulation signal power to both EOMs on North and South Path by 3 dB and 6 dB. This should reduce the modulation depth by 1/\sqrt{2}} and 1/2. After every change, a small displacement happens in the thermal control of the cavities, so I had to wait for some time to let it settle. The gains of the FSS loops were kept constant to make sure only the modulation depth is the parameter that is changing. Gain values were 24 dB and 16 dB for South COM and FAST gains, and 11 dB and 10 dB for North COM and FAST gain.

Inference:

  • There is almost no difference in noise upto1 kHz.
  • There is a new bump I'm seeing between 100 and 200 Hz though which was there on Dec 12th but not on Dec 13th measurements.
  • This bump might have been reduced due to a decrease in laser power or something might have changed between the two days. I'll check with increasing power what happens.
  • Above 1 kHz, we see that as modulation depth is deceased, we see a reduction in noise. The same goes for power.
  • Overall, this does show that the effect of these changes is more or less as expected and the effect of non-linearity, if any is not much.
  • It is still valuable to quantify properly how much the non-linearity might be affecting the final beatnote spectrum though. Working on it.

Data

Attachment 1: BeatnoteSpectrumwrtPowerandModindex.pdf  248 kB  Uploaded Fri Dec 13 12:45:30 2019  | Hide | Hide all
BeatnoteSpectrumwrtPowerandModindex.pdf
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