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  15101   Tue Dec 17 20:08:09 2019 shrutiUpdateGeneralPLL / PM measurement of Xend NPRO PZT

1. Some calculations

For a Unity Gain Frequency (UGF) of 1 kHz, assumed PZT response K_{VCO} of 1 MHz/V, Mixer response K_{M} of 25 mV/\pi rad, the required gain of the amplifier is

G = 2 \pi \times \text{UGF}/ (K_{VCO} K_M)

G ~ 0.8

2. Progress

- Measured the mixer response

Measuring mixer response:

- PSL laser temperature was adjusted so that beat frequency was roughly 25 MHz and the amplitude was found to be roughly -30dBm.

- At the RF port instead of the beat signal, a signal of 25 MHz + few kHz at -30 dBm was inputted. The LO was a 25 MHz signal was sent from the Marconi at 7 dBm.

- The mixer output was measured, with setup as in Attachment 1  Figure (A), on an oscilloscope. The slope near the small angle region of the sine curve would be the gain (in V/rad) and was found to be: K_M \approx 25 \text{ mV}/ \pi rad

- Since from the above calculations it seemed like an amplifer gain of 1 should work for the PLL, I rearranged the set up as in Figure (B) of Attachment 1 to actuate the X end NPRO PZT, I adjusted the PSL temperature (slow control) to try and match the frequency to 25 MHz, but couldn't lock the loop. I was monitoring the error signal after amplification (50 ohm output of the SR 560) which showed oscillations when the beat frequency was near 25 MHz and nothing significant otherwise.

- I used a 20 dB attenuator at the amplifier output and saw the beat note oscillate for longer, but maybe because it was a 50 ohm component in a high impedance channel it did not work either (?). I tried other attenuator combinations with no better luck.

- Is there a better location to add the attenuator? Should I pursue amplifying the beat signal instead?

- Also, it seemed like the beat note drift was higher than earlier. Could it be because the PMC was unlocked?

 

Quote:
 

 

Attachment 1: 20191217.png
20191217.png
  15117   Mon Jan 13 15:47:37 2020 shrutiConfigurationComputer Scripts / Programsc1psl burt restore

[Yehonathan, Jon, Shruti]

Since the PMC would not lock, we initially burt-restored the c1psl machine to the last available shapshot (Dec 10th 2019), but it still would not lock.

Then, it was burt-restored to midnight of Dec 1st, 2019, after which it could be locked.

  15129   Thu Jan 16 19:32:23 2020 shrutiUpdateGeneralPLL / PM measurement of Xend NPRO PZT

With Gautam's help today the PLL managed to be be locked for a few brief moments. Turns out the signal power of the beat was an issue.

What was changed prior to/ during the experiment:

1. The PSL shutter was closed so not light goes into the input mode cleaner.

2. HEPA turned up (will be turned back down to ~30%)

3. AOM driver offset voltage decreased from 1V to ~100 mV (this will be reverted to 1V by the end of today). This increases the beat signal by deflecting the zeroth order beam to create the beat.

4. Output of servo SR 560 sent to the PZT of the X NPRO laser (the cable was disconnected from the pomona box at the X end)

5. The SR560, mixer, LPF and cables required for connections were moved into the PSL enclosure.

6. The error and control signals were hooked up to the oscilloscope where the beat outputs were visible (the setup has been reverted back to the original).

 

Elog 14687 has a detailed description of the conditions that provide a stable lock. I was told that the PI controller (LB1005) may be a better servo than the SR560, but today it was not used.

1) Parameters during the more successful attempts:

LPF: 5 MHz, Mixer: ZP-3+

Gain set at SR560: varied, but generally 200

Filter at SR560: 1 Hz low pass (single pole? at least by the label)

2) The LO had to be very close (<2 MHz) to the beat frequency in order to achieve a lock for ~30s


gautam edits:

  • the error signal for the PLL was being sourced from the 20dB coupled port on the BeatMouth.
  • additionally, most of the power in the PSL beam coupled into the fiber was being deflected into the first order beam by team ringdown.
  • The Vpp of the mixer output (when using the coupled beat and low PSL beam power) was a paltry 5-10 mVpp no.
  • I suggested using the direct NF1611 output for this measurement instead of the coupled output (alternatively, use an amp). it's probably also better to use the LB1005 for locking the PLL, long term, this can be set up to be controlled remotely, and a slow PID servo can be used to extend the duration of the lock by servoing either the marconi carrier freq or the EX temp ctrl.
Quote:

1. Some calculations

For a Unity Gain Frequency (UGF) of 1 kHz, assumed PZT response K_{VCO} of 1 MHz/V, Mixer response K_{M} of 25 mV/\pi rad, the required gain of the amplifier is

G = 2 \pi \times \text{UGF}/ (K_{VCO} K_M)

G ~ 0.8

2. Progress

- Measured the mixer response

Measuring mixer response:

- PSL laser temperature was adjusted so that beat frequency was roughly 25 MHz and the amplitude was found to be roughly -30dBm.

- At the RF port instead of the beat signal, a signal of 25 MHz + few kHz at -30 dBm was inputted. The LO was a 25 MHz signal was sent from the Marconi at 7 dBm.

- The mixer output was measured, with setup as in Attachment 1  Figure (A), on an oscilloscope. The slope near the small angle region of the sine curve would be the gain (in V/rad) and was found to be: K_M \approx 25 \text{ mV}/ \pi rad

- Since from the above calculations it seemed like an amplifer gain of 1 should work for the PLL, I rearranged the set up as in Figure (B) of Attachment 1 to actuate the X end NPRO PZT, I adjusted the PSL temperature (slow control) to try and match the frequency to 25 MHz, but couldn't lock the loop. I was monitoring the error signal after amplification (50 ohm output of the SR 560) which showed oscillations when the beat frequency was near 25 MHz and nothing significant otherwise.

- I used a 20 dB attenuator at the amplifier output and saw the beat note oscillate for longer, but maybe because it was a 50 ohm component in a high impedance channel it did not work either (?). I tried other attenuator combinations with no better luck.

- Is there a better location to add the attenuator? Should I pursue amplifying the beat signal instead?

- Also, it seemed like the beat note drift was higher than earlier. Could it be because the PMC was unlocke

  15148   Thu Jan 23 20:08:49 2020 shrutiUpdateGeneralPLL / PM measurement of Xend NPRO PZT

Setup Update:

- No more SR 560, upgraded to LB1005 P-I controller.  Because: Elog 14687. Schematic of new setup shown in Attachment 1.

- For this, the Marconi was moved to the other (east) side of the PSL table and a power supply was also placed in the enclosure.

I think that the RF power at the mixer in this new configuration is 0 dBm (since the spectrum analyzer read ~ -20 dBm)

Progress Today:

- Turned up the HEPA to 100%, closed the PSL shutter, misaligned the ITMX, connected the LB1005 to the PZT. [The PZT has been reconnected to the X arm PDH servo, HEPA back to 20-30%]

- Tried to look for the PSL+X beat, but it was not there. Gautam identified the flipmount in the path which sorted it out (eventually), but there was no elog about itsurprise.

- After much trial, the loop seemed to lock with PI corner 1 kHz, gain ~2.9 (as read on knob), LFGL set to 90 dB. The beat note looked quite stable on the oscilloscope, but the error signal had an rms of ~100 mV (Rana pointed out that it could be the laser noise) and the lock lasted for ~1 min each time.

The parameters were similar to that in elog 14687. Why do we require such a high PI corner frequency and LFGL?

Attachment 1: Image-1.jpg
Image-1.jpg
  15169   Tue Jan 28 19:40:15 2020 shrutiUpdateGeneralPLL / PM measurement of Xend NPRO PZT

Over the past few days, I have been trying to make measurements of the phase modulation transfer function by modulating the X end laser PZT via PLL.

The setup was modified every time during the experiment in the same manner as mentioned in elog 15148.

I could not make the PLL lock for long enough to take a proper TF measurement, resulting in TFs that look like Attachment 1. The next step would be to use the method of a delay line frequency discriminator instead of the PLL.


Comments about locking with LB1005 PI controller:

  1. I do not understand why the high PI corner frequency of 1kHz or 3kHz was required to lock.
  2. The rms level of the error signal when locked was ~100 mV, which is 25% of the total mixer range (~400 mVpp). Decreasing the gain only caused the loop to go out of lock and did not decrease this noise in the error signal.
  3. The setup was also partly inside the PSL enclosure, with the HEPA turned to 100%, which is probably a noisy environment for this measurement. Closing and opening the shutters or any disturbance near the enclosure resulted in movement of the beat note up to 5 MHz.
  4. It may have been a better idea to actuate the PSL laser instead of the X NPRO because of its larger range, but would this solve the issue with the noise?
Attachment 1: PMTF.pdf
PMTF.pdf
Attachment 2: BeatSpectrum.pdf
BeatSpectrum.pdf
  15174   Wed Jan 29 12:29:33 2020 shrutiUpdateGeneraldelay line frequency discriminator for PM

 Today I began working on a TF measurement based on the delay line frequency discriminator setup in elog 4254 using a single mixer (without the 'I' and 'Q' readout).

For this, I re-organised the setup for the PLL measurement of the transfer function (elog 15148), increasing the HEPA for the initial changes while the PSL door was open, and then reverting it back to ~30%:

  • I removed the 20dB coupler and connected the splitter directly after the amplifer to split the beat note signal into two coaxial cables one of which was ~1.5m longer than the other
  • The recombined signals were combined in a mixer outside the PSL enclosure. I also replaced the 1.9 MHz LPF with a 5 MHz LPF.
  • I used an SR 560 to amplify the signal after the LPF.

With the above setup the power that was seen at each channel of the delay line was <1dBm, which is not ideal for the any of the available mixers.

After the group meeting, I changed the amplifer to ZHL-3A (that is near the beat mouth) instead of a ZFL-500HLN because it had a higher gain (~28dB as opposed to ~19dB of the latter). The power seen at each of the delay line channels is over 5.5 dBm. This is consistent with the estimation 0 dBm beat -> -20 dBm after 20dB coupler -> 8 dBm after amplifier -> 5 dBm after splitter with insertion loss of 3 dB.

Is this sufficient enough for the mixer to work? In Attachment 1: A shows the mixer output (point B in Attachment 2) when the IMC is locked, in B the IMC is unlocked at the middle of the spectrum, and each of the dips show the DC voltage being sent to the PSL temperature servo being decreased by 0.01 V.

Gautam pointed me to the location of a few other RF amplifiers (ZHL-32A+, ZHL-1A) which don't possess a higher gain but can be used without disrupting the ALS related work (I was told).

For shorter duration changes that I made later, I opened and closed the PSL enclosure doors without changing the HEPA.

Attachment 2 shows the current setup as is, but I might add a PSL servo tomorrow to stabilise its frequency corresponding to a null mixer output without driving anything else.

Attachment 1: 20200128.png
20200128.png
Attachment 2: IMG_BB01C068495A-1.jpeg
IMG_BB01C068495A-1.jpeg
  15180   Thu Jan 30 22:02:42 2020 shrutiUpdateGeneraldelay line frequency discriminator for PM

I could not find any level 3 mixers, but by adjusting the beat frequency the power in each of the delay line channels rose to almost 6.5 dBm.

In short: Delay line seems to work

Things I did earlier today:

  1. Played with the slow servo on the FSS screen, but then reset the parameters to what was there before (Later found out that this was to lock the PSL freq to the IMC when the IMC power is significant.)
  2. Connected the AG 4395A to the X PZT
  3. Closed the PSL shutter

Transfer function measurement: (Refer Attachment 1)

Everything about the setup remained as I had left it earlier: described in elog 15174

except

  • SR560 gain set to 10, DC coupled
  • DC block at channel A of Agilent (The measurement was A/R)

I did not use a slow servo, but took individual sweeps adjusting the PSL temperature each time to bring the error voltage between +/-25 mV. The beat frequency was over 100 MHz.

For the plot posted in Attachment 1, the measurement paramters are the following. Will do further measurements/analysis tomorrow.

# AG4395A Measurement - Timestamp: Jan 30 2020 - 21:58:00
# Parameter File: TFAG4395Atemplate.yml
#---------- Measurement Parameters ------------
# Start Frequency (Hz): 50000.0, 50000.0
# Stop Frequency (Hz): 1000000.0, 1000000.0
# Frequency Points: 801, 801
# Measurement Format: LOGM, PHAS
# Measuremed Input: AR, AR
#---------- Analyzer Settings ----------
# Number of Averages: 1
# Auto Bandwidth: Off, Off
# IF Bandwidth: 1000.0, 1000.0
# Input Attenuators (R,A,B): 0dB 0dB 0dB 
# Excitation amplitude = -20.0dBm

Quote:

yes, its fine to use this with a level 3 or level 7 mixer; let's see some PM transfer functions !

Quote:

Is this sufficient enough for the mixer to work?

Attachment 1: Figure_2.png
Figure_2.png
  15197   Fri Feb 7 09:45:03 2020 shrutiUpdateGeneralAM at X end

I took a few AM TF measurements at the X end for which I:

  • Misaligned the ITMX (then re-aligned it)
  • Opened the X green shutter during the measurements and closed it at the end
  • Moved the Agilent from the PSL area to the X end, the delay line and mixer still remains near the PSL area (will move it soon)
  • Took a bunch of TFs

I will post the data soon.

  15206   Tue Feb 11 16:39:00 2020 shrutiUpdateALSAM/PM

The results of the AM/PM measurements:

  • Attachment 1: Traces of 9 AM TFs overlaid on top of each other, calibrated by measuring the voltage at the ‘GREEN_REFL’ output where the TF was measured (described in elog 40m:15197). This was almost exactly 2 V.
  • Attachment 2: Traces of 9 PM TFs also overlaid measured using DLFD (as described in elog 40m:15180). Calibrated using the measured ~600 mV pk-pk voltage. The phase plots were unwrapped (shifted by 180 deg if needed) so that each started from roughly 0 deg.

Both the AM and PM TFs were scaled to make them have the same average value. Manually adjusting the delay line offset for each measurement using the oscilloscope was probably not accurate enough and therefore resulted in different scaling which this should somewhat compensate.

Attachment 3:

  • The orange and green lines are the averages of the PM and AM values of Attachments 1 and 2 respectively.
  • The solid red line is at 230 kHz, which was the previously chosen value for PDH locking. The peak seems to have shifted to the left from previous measurements (elog 40m:12077).
  • A horizontal black dashed line is drawn to show where the ratio is 10^5.
  • The red regions correspond to frequencies where PM/AM > 10^5 [only shown for frequencies greater than 200kHz], these are roughly (in kHz):
    • 211.4-213.9
    • 221.4-230.7 (peak at 225.642)
    • 240.8-257.9
    • ~748.3
    • 753.3-799.8, two largest peaks at 763.673 and 770.237
    • 809.6-829.3, peak at 819.472
    • 839.2-842.4
    • 881.8-891.7

Updated Calibration

Attachment 2 and 3 were miscalibrated due to an error in my understanding of the delay line, but the net result of the change in factors is qualitatively almost the same and the position of the major peaks remain predominantly unchanged.

The new plot is in Attachment 5.

The new calibration factor used: 5 MHz/V at the output of the mixer to obtain the frequency modulation and then division by the mod. freq. to obtain PM.

5 MHz/V because changing the PZT voltage by 0.01 V=> change in beat frequency by 0.1 MHz, which was seen as a 20 mV change in the delay line mixer output.

Again, the calibration is not very precise and I will probably repeat this experiment at some point more precisely.

Attachment 1: AM.pdf
AM.pdf
Attachment 2: PM.pdf
PM.pdf
Attachment 3: Ratio_all.pdf
Ratio_all.pdf
Attachment 4: Ratios_FM_PM.pdf
Ratios_FM_PM.pdf
Attachment 5: Ratio_all_new.pdf
Ratio_all_new.pdf
  15207   Tue Feb 11 19:11:35 2020 shrutiUpdateComputer Scripts / ProgramsMATLAB on donatella

Tried to open MATLAB on Donatella and found the error:


MATLAB is selecting SOFTWARE OPENGL rendering.

 

License checkout failed.
License Manager Error -9
This error may occur when: 
-The hostid of this computer does not match the hostid in the license file. 
-A Designated Computer installation is in use by another user. 
If no other user is currently running MATLAB, you may need to activate.

Troubleshoot this issue by visiting: 
http://www.mathworks.com/support/lme/R2015b/9

Diagnostic Information:
Feature: MATLAB 
License path: /home/controls/.matlab/R2015b_licenses/license_donatella_865865_R2015b.lic:/cvs/cds/caltech/apps/lin
ux64/matlab15b/licenses/license.dat:/cvs/cds/caltech/apps/linux64/matlab15b/licenses/license_chiara_
865865_R2015b.lic:/cvs/cds/caltech/apps/linux64/matlab15b/licenses/license_pianosa_865865_R2015b.lic 
Licensing error: -9,57.


So I used  my caltech credentials to get an activation key for the computer. I could not find the option for a campus license so I used the individual single machine license.

Now it can be run by going to the location:

/cvs/cds/caltech/apps/matlab17b/bin

and running

./matlab

On opening MATLAB, there were a whole bunch of other errors including a low-level graphics error when we tried to plot something.

  15211   Thu Feb 13 21:30:55 2020 shrutiUpdateALSALS OOL noise with arms locked

[Meenakshi, Gautam, Shruti]

Summary:

- We initially aligned the arm cavities to get the green lasers locked to them. For the X arm cavity, we tweaked the ITMX and ETMX pitch and yaw and toggled the X green shutter until we saw something like a TEM00 mode on the monitor and a reasonable transmitted power.

- With the LSC servo enabled, the IR light also became resonant with the cavities.

- Then we measured the noise in different configurations. Attachment 1 shows the the ALS OOL (in the IR beat signal) noise with the arms locked inidividually via PDH.


The script for plotting the ALS beat frequency noise is:

users/Templates/ALS/ALS_outOfLoop_Ref.xml
Attachment 1: 20200213_ALS.pdf
20200213_ALS.pdf
  15213   Fri Feb 14 14:02:13 2020 shrutiUpdateALSALS OOL noise with arms locked

[Meenakshi, Shruti]

Even though we were not able to lock the the IR beat (by enabling LSC) during the day possibly because of increased seismic activity, we tried to the measure the ALS beat frequency noise by changing the PDH side-band frequency to different values.

I tried choosing values that corresponded to the peaks in the PM/AM as found in elog:15206 but for some reason unknown to us the cavity did not lock between 700-800 kHz.

The three attachments have data for different sideband frequencies:

Attachment 1: 819.472 kHz (peak in PM/AM, measured around noon)

Attachment 2: 225.642 kHz (peak in PM/AM, measured earlier in the morning)

Attachment 3: 693.500 kHz (not a peak in PM/AM)

We don't think these plots mean much and will do the measurement at some quieter time more systematically.

 

While doing the experiment, the ITMY pitch actuation was changed from -2.302 to -2.3172V because it locked better.

The ITMX, ETMX alignment was also tweaked to try to lock with different sideband frequencies and then restored to the values that were found earlier in the morning.

Attachment 1: 819472_10.pdf
819472_10.pdf
Attachment 2: 225642_10.pdf
225642_10.pdf
Attachment 3: 693500_10.pdf
693500_10.pdf
  15216   Tue Feb 18 18:14:59 2020 shrutiUpdateALSALS OOL noise with arms locked

We proceeded with the trying to measure the ALS out-of-loop noise of the X arm when the X arm cavity is green-locked using different PDH sideband frequencies.

Before doing the experiment, Koji helped us with getting the arm cavities locked in IR using LSC (length) and ASC (angular).

With the arms locked in IR and green, we repeated the same measurements as before at different sideband frequencies (Refer Attachment 1 - label in Hz). We did not optimize the phase nor did we look at the PDH error signal today which is possibvly why we did not see an improvement in the noise. We will look into this possibly tomorrow.

Attachment 1: ALSNoise.pdf
ALSNoise.pdf
  15218   Fri Feb 21 10:59:08 2020 shrutiUpdateALSPDH error signals?
Here are a few PDH error signals measured without changing the servo gain or phase from that optimized for 231.25 kHz. This was done by keeping the X arm cavity and laser unlocked but keeping the shutter for green open; so I did not force a frequency sweep but saw the unhindered motion of cavity wrt the laser using the PDH servo error monitor channel from the box (not sure if this is the best way to do it?).
 
Koji mentioned that there is a low pass filter with a cutoff frequency probably lower than 700 kHz which at the moment would hinder the efficacy of the locking at higher frequencies. The transfer function on the wiki suggests the same, although we are yet to investigate the circuit.
 
I measured the maximum range in the linear region of the signal, and here are the results:
  • Attachment 1: 231.25 kHz (current PDH sideband mod freq): 1.7 V
  • Attachment 2: 225.642 kHz: 1.2 V
  • Attachment 3: 100 kHz: 900 mV
  • Attachment 4: 763.673 kHz: 220 mV
Right now we have only inverted the phase to try locking at different frequencies (no finer adjustments were performed so elog 15216 cannot be an accurate representation of the true performance)
 
Ideas from the 40m meeting for adjusting the phase:
  1. Delay line for adding extra phase (would require over 40m of cable for 90 deg phase shift)
  2. Using two function generators for generating the sideband, clocked to each other, so that one can be sent to the PZT and the other to the mixer for demodulation.
  3. Use a different LPF (does not seem very useful for investigating multiple possible frequencies)

Once we adjust the phase we may be able to increase the servo gain for optimal locking. Unless it may be a good idea to increase the gain without optimizing the phase?

Attachment 1: IMG_0082.jpg
IMG_0082.jpg
Attachment 2: IMG_0083.jpg
IMG_0083.jpg
Attachment 3: IMG_0084.jpg
IMG_0084.jpg
Attachment 4: IMG_0085.jpg
IMG_0085.jpg
  15220   Fri Feb 21 20:44:18 2020 shrutiUpdateALSALS OOL noise and PDH

[Meenakshi, Shruti]

In order to adjust the relative phase for PDH locking, we used the Siglent SDG 1032X function generator which has two outputs whose relative phase can be adjusted.

This Siglent function generator was borrowed from Yehonathan's setup near the PSL table and can be found at the X end disconnected from our setup after our use.

Initially, we used the Siglent at 231.250 kHz and 5 Vpp from each output with zero relative phase to lock the green arm cavity. By moving the phase at intervals of 5deg and looking at the PDH error signals when the cavity was unlocked we concluded that 0deg probably looked like it had the largest linear region (~1.9 V on the yaxis. Refer elog 15218 for more information) as expected.

Then we tried the same for 225.642 kHz, 5 Vpp, and found the optimal demod phase to be -55deg, with linear region of ~3 V (Ref. Attachment 2). A 'bad' frequency 180 kHz was optimized to 10deg and linear region of ~1.5 V.

The error signals at higher frequencies appeared to be quite low (not sure why at the moment) and tuning the phase did not seem to help this much.

For the noise measurement, the IFO arms were locked to IR and green, but even after optimizing the transmission with dither, we couldn't achieve best locking (green transmission was around ~0.2). Further, the IMC went out of lock during the experiment after which Koji helped us by adjusting the gains a locking point of the PMC servo. Attachment 1 contains some noise curves for the 3 frequencies with a reference from an earlier 'good' time.

Attachment 1: ALSNoise.pdf
ALSNoise.pdf
Attachment 2: IMG_0086.jpg
IMG_0086.jpg
  12342   Wed Jul 27 15:03:02 2016 sisyphusMetaphysicsSUSBroken wire

While tightening the bolts on the ETMX wire clamp, the wire broke. All four face magnets broke off. 

Fortunately, no pieces were lost.

  4958   Fri Jul 8 20:50:49 2011 sonaliUpdateGreen LockingPower of the AUX laser increased.

The ETMY laser was operating at 1.5 A current and 197 mW power.

For the efficient frequency doubling of the AUX  laser beam at the ETMY table, a higher power is required.

Steve and I changed the current level of the laser from 1.5 A to 2.1 A in steps of 0.1 A and noted the corresponding power output . The graph is attached here.

The laser has been set to current 1.8 Amperes. At this current, the power of the output beam just near the laser output is measured to be 390 mW.

The power of the beam which is being coupled into the optical fibre is measured to be between 159 mW to 164 mW (The power meter was showing fluctuating readings).

The power out of the beam coming out of the fibre far-end at the PSL table is measured to be 72 mW. Here, I have attached a picture of the beam paths of the ETMY table with the beams labelled with their respective powers.

Next we are going to adjust the green alignment on the ETMY and then measure the power of the beam.

At the output end of the fibre on the PSL, a power meter has been put to dump the beam for now as well as to help with the alignment at the ETMY table.

Attachment 1: Graph3.png
Graph3.png
Attachment 2: ETMY_beam_powers.png
ETMY_beam_powers.png
  4965   Thu Jul 14 02:32:11 2011 sonaliUpdateGreen LockingPower of the AUX laser increased.

Quote:

The power of the beam which is being coupled into the optical fibre is measured to be between 159 mW to 164 mW (The power meter was showing fluctuating readings).

The power out of the beam coming out of the fibre far-end at the PSL table is measured to be 72 mW. Here, I have attached a picture of the beam paths of the ETMY table with the beams labelled with their respective powers.

 For the phase locking or beat note measuring we only need ~1 mW. Its a bad idea to send so much power into the fiber because of SBS and safety. The power should be lowered until the output at the PSL is < 2 mW. In terms of SNR, there's no advantage to use such high powers.

  4973   Fri Jul 15 13:48:56 2011 sonaliUpdateGreen LockingPower of the AUX laser increased.

Quote:

Quote:

The power of the beam which is being coupled into the optical fibre is measured to be between 159 mW to 164 mW (The power meter was showing fluctuating readings).

The power out of the beam coming out of the fibre far-end at the PSL table is measured to be 72 mW. Here, I have attached a picture of the beam paths of the ETMY table with the beams labelled with their respective powers.

 For the phase locking or beat note measuring we only need ~1 mW. Its a bad idea to send so much power into the fiber because of SBS and safety. The power should be lowered until the output at the PSL is < 2 mW. In terms of SNR, there's no advantage to use such high powers.

 

Well,the plan is to put in  a neutral density filter in the beam path before it enters the fibre. But before I could do that, I set up the camera on the PSL table to look at the fiber output . I will need it while I realign the  beam after putting in the Neutral Density Filter. I have attached the ETMY layout with the Neutral Density filter in place herewith.

Attachment 1: ETMY_after_fibre_coupling_labelled.pdf
ETMY_after_fibre_coupling_labelled.pdf
  10   Tue Oct 23 11:08:20 2007 steveOtherGeneralbrush fires
There are big brush fires around LA
40 days plot show no effect in the 40m lab
Attachment 1: brushfires.jpg
brushfires.jpg
  12   Wed Oct 24 08:58:09 2007 steveOtherPSLlaser headtemp is up
C1:PSL-126MOPA_HTEMP is 19.3C

Half of the chiller's air intake was covered by loose paper
Attachment 1: htempup.jpg
htempup.jpg
  17   Fri Oct 26 09:10:17 2007 steveRoutinePEMPEM &PSL trend
The fires are out, lab particle counts are up.
Psl HEPAs are at 100% and mobel HEPAs are just turned on
20 days plot and 5 hrs plot below
Attachment 1: counts&psl.jpg
counts&psl.jpg
Attachment 2: 5dcounts.jpg
5dcounts.jpg
  23   Mon Oct 29 09:16:31 2007 steveRoutineVACthe rga is back
We had no filament current since last power glitch of Oct. 8, 2007
First I thought that the filament was lost, but it was only bad contact.
The rga head pins were oxidized. Rga was turned back on last Friday.
It's temp is 55.3C normal
Attachment 1: rgaisback.jpg
rgaisback.jpg
  24   Mon Oct 29 09:46:50 2007 steveRoutineVACvac & pem trend
Pumpdown 64 pumped by maglev for 125 days
pd64-m-d125

Rob, can you tell me, when did the fire start on this plot?
Attachment 1: pd64md125.jpg
pd64md125.jpg
  44   Thu Nov 1 09:17:27 2007 steveRoutineVACvent 64
Yesterday before vent I could not lock MC, therfore I could not measure the
transmitted power at MC2
The vent went well. We had lots of help.

We could not find the Nikon D40
PLEASE BORROW THINGS when taking them away
and bring them back promtly.

The laser was turned off for better visibility.

I see clean room frorks laying around here and there.
Please put them away so we do not carry excess particles into the chamber.
Attachment 1: vent64.jpg
vent64.jpg
  57   Fri Nov 2 08:59:30 2007 steveBureaucracySAFETYthe laser is ON
The psl laser is back on !
  65   Tue Nov 6 09:14:37 2007 steveSummaryVACpump down 65
8 hr plot,
precondition: 5 days at atm,
vent objective: drag wiping mc1, mc2 & mc3 accomplished,
hardware changes: IOO access connector, mc2 chamber door south & west
were removed and reinstalled
pump down mode: slow to avoid steering up dust
One roughing pump was used with closed down valve position in the first 4 hrs

Andrey was very helpful
Attachment 1: pd65.jpg
pd65.jpg
  66   Tue Nov 6 09:45:22 2007 steveSummarySUSvent sus trend
The mc optics dragwippings were done by locking optics by eq stops and rotating-moving
cages so access were good. This technic worked well with mc1 & mc2
MC3 osems were reoriented only.
Attachment 1: ventsustrend.jpg
ventsustrend.jpg
  76   Wed Nov 7 09:38:01 2007 steveUpdateVACrga scan
pd65-m-d2 at cc1 6e-6 torr
Attachment 1: pd65d2.jpg
pd65d2.jpg
  81   Wed Nov 7 16:07:03 2007 steveUpdatePSLPSL & IOO trend
1.5 days of happy psl-ioo with litle bumps in C1:PSL-126MOPA_HTEMP
Attachment 1: psl1.5dtrend.jpg
psl1.5dtrend.jpg
  83   Thu Nov 8 11:40:21 2007 steveUpdatePEMparticle counts are up
I turned up the psl HEPA filter to 100%
This 4 days plot shows why
Attachment 1: pslhepaon.jpg
pslhepaon.jpg
  88   Fri Nov 9 09:37:55 2007 steveUpdatePSLhead temp hiccup
Just an other PSL-126MOPA_HTEMP hiccup.
The water chiller is at 20.00C
Attachment 1: headtempup.jpg
headtempup.jpg
  113   Fri Nov 16 18:46:49 2007 steveBureaucracyPSL MOPA was turned off & on
The "Mohana" boys scouts and their parents visited the 40m lab today.
The laser was turned off for their safety.
It is back on !
  114   Mon Nov 19 14:19:25 2007 steveOmnistructurePEMjackhammer
The construction personal successfully jackhemmered a fence around the "Drever's parking slot"
There is no parking space available close by
Attachment 1: jackhammer.jpg
jackhammer.jpg
Attachment 2: jackhammer2.jpg
jackhammer2.jpg
  115   Mon Nov 19 14:32:10 2007 steveBureaucracySAFETYgrad student safety training
John Miller and Alberto Stochino has received the 40m safety bible.
They still have to read the laser operation manual and sign off on it.
  122   Mon Nov 26 10:17:31 2007 steveOmnistructureSUSetmy sus damping restored
20 days plot is showing etmy loosing damping 4 times.
I zoomed in with each event. Three of them could of been triggered
by garbage loading just outside. However attachment 2 plot demonstrating that small earthquake or seismic event
did not tripped etmy damping.
The fourth event was preceded by a 4-5 hrs of continous rise of the rms motion at C1:SUS-ETMY_LLPD_VAR
Attachment 1: etmyrms20d.jpg
etmyrms20d.jpg
Attachment 2: etmyrmseq.jpg
etmyrmseq.jpg
  129   Wed Nov 28 08:47:29 2007 steveOmnistructureVACrga is out of order
The rga is not working since Nov 10
The controller is broken.
pd65-m-d23
Attachment 1: pd65d23.jpg
pd65d23.jpg
  200   Wed Dec 19 11:31:01 2007 steveOmnistructurePEMaircond filter maintenance
Jeff is working on all air condiontion units of the 40m lab
This we do every six months.
Attachment 1: acfilters6m.jpg
acfilters6m.jpg
  203   Wed Dec 19 16:40:12 2007 steveUpdateSAFETYlaser safety glasses measured
I measured the coarse transission at 1064nm of the 40m safety glasses today.

12 pieces of UVEX # LOTG-YAG/CO2 light green, all plastic construction, ADSORBANT

3 pieces of 6KG5, Scott colored filter glass type,

individual prescription glasses: alan, bob, ben, jay and steve

7 pieces of dual waveleght glasses

These glasses showed 0.00mW transmission out of 170mW Crysta Laser 1064
  220   Thu Jan 3 08:53:55 2008 steveUpdateSUSetmy vs etmx
Rana have corrected sus gain damping setting of ETMY 8 days ago

gain settings: pos, pit, yaw & sd
etmx: 4,2,2,& -16
etmy: 4,2,2,& 50
Attachment 1: sus.jpg
sus.jpg
  221   Thu Jan 3 09:12:59 2008 steveUpdatePSLMZ servo
Here is MZ trend for one year and 40 days.
Now days it runs out of range on the low side.
This is the weakest link in the psl today.
Attachment 1: mz1y.jpg
mz1y.jpg
Attachment 2: mz40d.jpg
mz40d.jpg
  222   Thu Jan 3 09:55:11 2008 steveUpdateSUSetmy sus damping restored
ETMY watch dog was lost at midnight
Attachment 1: etmy12h.jpg
etmy12h.jpg
  225   Fri Jan 4 08:42:03 2008 steveUpdateSUSetmy trips again
ETMY sus damping tripped at 6am this morning
It was reset. We should put an accelerometer to the south end to see
the garbage dumping effect.
Attachment 1: etmy20m.jpg
etmy20m.jpg
Attachment 2: etmy120s.jpg
etmy120s.jpg
Attachment 3: etmysenV.jpg
etmysenV.jpg
  226   Mon Jan 7 09:01:39 2008 steveUpdateSUSBS sus damping restored
The BS sus damping was lost at 8am Sunday morning.
Attachment 1: bssdl.jpg
bssdl.jpg
  232   Thu Jan 10 10:38:02 2008 steveUpdateSUSetmy damping restored
The IST building onstruction has really started yesterday and continuing today with big heavy ground breaking
machinary. The MC is holding lock and the suspentions are hanging on.

ETMY does not like this.

SUS-MC2_LLPD_VAR monitor is a good indicator of seismic activity on this 12 days plot
Attachment 1: etmysus.jpg
etmysus.jpg
Attachment 2: sustrend16d.jpg
sustrend16d.jpg
  233   Thu Jan 10 12:08:23 2008 steveUpdateSUSwhy did the BS move?
Attachment 1: bshopped.jpg
bshopped.jpg
  235   Thu Jan 10 15:04:04 2008 steveUpdateSUSilluminator light effect on BS position
The bs chamber illuminator light was turned on this morning and left on.
Earlier on Rana noticed that the bs moved.
I follwed up to see what happened. I turned off oplev servo and tried to recenter on oplev pd
by adjusting pitch and yaw biases. It did not move. I looked at suspention and realized that the
illuminator was still on. I turned it off and to my amazement the the AP spot started flashing
Attachment 1: bssusilum.jpg
bssusilum.jpg
  237   Mon Jan 14 14:41:09 2008 steveUpdateSUSetmy sus damping restored & mz relocked
Tree days trend of MZ HV drift is typical these days.
So as the etmy sus inability to hold damping for longer then 2-3 days.
Attachment 1: etmysus&mzhvtrend.jpg
etmysus&mzhvtrend.jpg
  254   Wed Jan 23 09:27:55 2008 steveUpdate etmy sus damping restored
Seismis event trips etmy
Attachment 1: etmysus.jpg
etmysus.jpg
  255   Wed Jan 23 11:41:06 2008 steveUpdatePEMsulfur smell in 40m
Led - acid car batteries were overcharged in the machine shop next door
and sulfuric acid smell is coming over to the ifo room.

Entry room 103 is specially bad.
ELOG V3.1.3-