40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
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ID Date Author Typeup Category Subject
  584   Fri Jun 27 18:03:46 2008 JenneUpdateElectronicsAnother bad cable in the MC servo
Eric was helping me to measure the response of the LO input on the MC's Demod board, and when we disconnected the end of the cable between the demod board and the delay line phase shifter for the 29.5MHz oscillator, we noticed that the phase shifter's end of the cable was loose, like the connector wasn't fully connected. When we checked it by wiggling the connector, the SMA end fell off. I made a new SMA end for the cable, and reinstalled the cable. The MC locked as soon as I plugged the cable in, so everything seems good again. I tried to not change the cable length when I remade the connector, but the cable is shorter than it was by a small amount, due to the way the end fell off.
  585   Fri Jun 27 18:21:01 2008 JenneUpdateElectronicsResponse of the LO input on the MC demod board
The alarm handler has been flipping out saying that the LO input of the MC's demod board is too low, so at Rana's suggestion, Eric and I measured the response of the LO input. We used an SR345 function generator at 29.485MHz and several different amplitudes to make a table. The demod board should see an input from the LO between 0-2dBm. When I measured what was going into the LO input from the 29.5MHz delay line phase shifter, the LO input was seeing 4dBm. I'm going to put a 3dB attenuator between the phase shifter and the demod board.

Also, now that we have this table of response values, I'm going to change the settings of the alarm handler to something more reasonable.
Amplitude of 29.485MHz input sine wave [dBm]    |        Value of channel C1:IOO-MC_DEMOD_LO
--------------------------------------------    |        -----------------------------------
-10                                             |        -0.000449867
-8                                              |        -0.000449867
-6                                              |        -0.000449867
-4                                              |        0.000384331
-2                                              |        0.00526733
0                                               |        0.0199163
2                                               |        0.0492143
4                                               |        0.0931613
6                                               |        0.161523
8                                               |        0.229885
10                                              |        0.293364
  586   Fri Jun 27 19:59:44 2008 JohnUpdateComputersc1iovme
C1susvme2 and C1iovme crashed which sent the optics swinging and tripped the watchdogs.

Koji and I were able to restore c1susvme2 without any trouble.

We have been unable to revive c1iovme. We have tried telneting in and running startup.cmd,
the process runs for a while then hangs with "DAQ init failed -- exiting".

Resetting the board doesn't help. I didn't try keying the whole crate.

All optics are back to normal with damping restored.
  587   Sat Jun 28 03:10:25 2008 robUpdateComputersc1iovme

Quote:
C1susvme2 and C1iovme crashed which sent the optics swinging and tripped the watchdogs.

Koji and I were able to restore c1susvme2 without any trouble.

We have been unable to revive c1iovme. We have tried telneting in and running startup.cmd,
the process runs for a while then hangs with "DAQ init failed -- exiting".

Resetting the board doesn't help. I didn't try keying the whole crate.

All optics are back to normal with damping restored.


I tried keying the crate, then keying the DAQ controller & AWG, then powering down & restarting the framebuilder.
On coming up, the framebuild doesn't start a daqd process, and I can't get one to start by hand (it just prints "652", and then stops).
No error messages and daqd doesn't appear in the prstat.

I then tried keying the DAQ controller again (after the fb0 reboot), which blew the watchdogs on all the suspensions. So then I went around and keyed all the crates.

Now, the suspension controllers are back online. Still no c1iovme, and now the framebuilder/DAQ/AWG are also hosed. We can try keying all the crates again, in the order that Yoichi did last week.

After some more poking around, I found the daqd log file. It's now complaining about

Jun 28 03:00:39 fb daqd[546]: [ID 355684 user.info] Fatal error: channel `C1: PSL-FSS_MIXERM_F' is duplicated 126

This is the second error message like this. It first complained about C1: PSL-FSS_FAST_F, so I commented that out of C1IOOF.ini and rebooted the framebuilder (note this is an actual reboot of the full solaris machine). Eventually I discovered that C1IOOF.ini and C1IOO.ini are essentially identical. They presumably will keep getting these duplicate channel errors until one of them is completely removed.

C1IOO.ini has a modification time of seven PM on Friday night. Who did this and didn't elog it? I've now modified C1IOOF.ini, and I don't remember when it was last modified.
  588   Sat Jun 28 14:56:44 2008 JohnUpdateComputersini files
In short, I was editing the ini files yesterday evening, I didn't e-log it and after some investigation this afternoon it apears
that I am to blame for all the computer problems which followed.


I wanted to edit C0EDCU.ini and C1IOOF.ini to change C1: PSL-FSS_FAST to a fast channel as C1: PSL-FSS_FAST_F
was dead.

I opened these files and made backups. It appears this is where it all went awry. My backup for C1IOOF
is called C1IOO.ini.090627 i.e. missing the F.

Later c1susvme2 and c1iovme crashed. After failing to bring c1iovme back I wondered if my edits had
caused the problems so I restored the back up files. It appears that here I wrote over C1IOO with my backup of
C1IOOF (presumably because I had made a typo in the name).

To remedy the situation we could restore C1IOO from e.g. chans/archive/C1IOO_080618_160028.ini

No excuses for not e-logging this activity.
  589   Sat Jun 28 23:23:50 2008 JohnUpdateComputersRebooting
All of the computers are now showing green lights.

Remaining problems:

Alignment scripts are failing with "ERROR: LDS - NDS server error #13"
I think this is a server transmission error.

Dataviwer shows all channels as zero.
  590   Sun Jun 29 02:33:28 2008 KojiUpdateGeneralAbs. Len. Meas. ~ Optical setup (I)
I have constructed the beam injection optics for the abs length measurement.

The injection beam was coarsely aligned to the interferometer. The reflected beam from SRM was already seen at AS CCD.
I have attached the optical configration for this measurement and the optics layout at the AP table.

I am going to go to LHO for three weeks. During the absence Alberto tunes the mode matching and the alignment of the interferometer.

In the process of making this report, I noticed that one of the iris apertures is about disturbing the beam for OMCR CCD. I will check this before I go to Hanford. Also an RF spectrum analyzer is at the AP table. I try to return this near the PSL on Monday morning.

Attachment 1: Optical configuration for the abs length measurement.
1) One of the arms is locked to the PSL beam by the main control system (red).
2) A laser beam is injected from the AS port (blue). This laser essentially has different frequency from that of PSL.
3) The injected beam and the outgoing PSL beam appear at the output of the faraday in the injection system.
4) They beat each other at the frequency difference of those two lasers.
5) A PLL is used to lock the frequency difference to a local oscillator (LO).
6) The LO frequency is swept at around 3.87MHz, that is the approximate FSR frequency of the arm cavity.
7) If the LO frequency hits the FSR within the resonant width, the beating also appears at the transmitted light as the injected beam also becomes resonant to the arm cavity.
8) Amplitude of the beating at the transmitted light is measured by a RF spectrum analyzer as a function of the LO frequency. We get the FSR frequency (= the arm cavity length) from the top of the resonance.

Attachment 2: Optics at the AP table for the laser injection
700mW NPRO, laser source. vertically polarized.
Periscope, to raise the beam 1 inch to make the beam at the 4 inch elevation.
INJ_SM1/INJ_SM2, steering mirrors to align the injection beam to the IFO beam.
HWP1, half wave plate to make the beam to the farady horiz-polarized. nominal 42deg on the readout.
FI, Faraday isolator for protection of the NPRO from the returning light, for obtaining the returning light.
HWP2, to make the beam from the Faraday horiz-polarized. nominal 357deg on the readout.
MM_Lens, f=125mm to match the laser mode to the IFO beam.
SM1/SM2, steering mirrors to align the IFO beam to the Farady Isolator.
IRIS1/IRIS2, for the coarse alignment of the injection beam.
FLIP, flipper mount to turn on/off the injection optics.

Alignment procedure of the injection system
0) Ignite NPRO several hours before the experiment so that the laser frequency can be stable.
1) Turn up FLIP. Close the shutter of NPRO.
2) Adjust SM1/SM2 so that the ifo beam can appear at the output of FI.
3) Adjust height and position of IRIS1/IRIS2 with regard to the ifo beam so that the ifo beam goes through IRIS1/IRIS2 even when they are closed.
4) Turn down FLIP. Open the shutter of NPRO.
5) Adjust INJ_SM1/INJ_SM2 so that the injection beam can go through IRIS1/IRIS2 even when they are closed.
6) At this time, it is expected that the reflection of the injection beam from SRM appears at AS CCD, if SRM is aligned.
7) Adjust INJ_SM1/INJ_SM2 so that the injection beam at AS CCD can overlap to the IFO beam.
8) Confirm the beam at the output of the FI also overlaps.
---- We are here ----
9) Change the ifo configuration to the X or Y arm only.
10) Scan the crystal temperature of the 700mW NPRO in order to try to have the beating of the two beams at the PD. AS OSA may be useful to obtain the beating.
11) Once the beating is obtained, adjust INJ_SM1/INJ_SM2 such that the beating amplitude is maximized.
Attachment 1: optical_configuration.png
optical_configuration.png
Attachment 2: optical_layout_ap_table2.png
optical_layout_ap_table2.png
Attachment 3: optical_layout_ap_table2.pdf
optical_layout_ap_table2.pdf
  592   Sun Jun 29 14:53:02 2008 robUpdateComputersRebooting

Quote:
All of the computers are now showing green lights.

Remaining problems:

Alignment scripts are failing with "ERROR: LDS - NDS server error #13"
I think this is a server transmission error.

Dataviwer shows all channels as zero.


Fixed. Just started the testpoint manager on fb40m.


su
/usr/controls/tpman &
  597   Sun Jun 29 20:29:48 2008 ranaUpdatePSLCorrelation of PSL SLOW control v. Room temperature
Attachment 1: slowtemp.png
slowtemp.png
  598   Mon Jun 30 01:49:06 2008 JohnUpdateIOOMC work
I'm in the process of aligning the mode cleaner/ input beam.

I turned off the WFS and cleared their histories, adjusted the input periscope and re-aligned the mode-cleaner accordingly.
I then unlocked the cavity and centred the beams on the WFS.

MC transmission is ~3.3 and the REFL beam looks a little better.

However, turning the WFS on now lowers the transmission. More thought tomorrow.

I'm leaving the MC locked with WFS off.
  599   Mon Jun 30 05:33:38 2008 KojiUpdateGeneralAbs. Len. Meas. ~ Optical setup (II)
o The position of the iris was adjusted so as not to disturub the beam for OMCR CCD.

o The RF spectrum analyzer was returned to the place of the network analyzer.


Quote:

In the process of making this report, I noticed that one of the iris apertures is about disturbing the beam for OMCR CCD. I will check this before I go to Hanford. Also an RF spectrum analyzer is at the AP table. I try to return this near the PSL on Monday morning.
  600   Mon Jun 30 08:59:23 2008 steveUpdateIOOIOO-MC_DEMOD_LO is low
The alarm handler is beeping relentlessly: asking for help in high partical count and low demod signal
Attachment 1: demlo.jpg_____
demlo.jpg_____
  601   Mon Jun 30 09:46:15 2008 JohnUpdateIOOMC WFS
MC WFS are on. They seem to do some good during the day.
  605   Mon Jun 30 15:56:22 2008 JenneUpdateElectronicsFixing the LO demod signal
To make the alarm handler happy, at Rana and John's suggestion I replaced R14 of the MC's Demod board, changing it from 4.99 Ohms to 4.99 kOhms. This increased the gain of the LO portion of the demod board by a factor of 10. Sharon and I have remeasured the table of LO input to the demod board, and the output on the C1:IOO-MC_DEMOD_LO channel:

Input Amplitude to LO input on demod board [dBm]: | Value of channel C1:IOO-MC_DEMOD_LO
------------------------------------------------- | -----------------------------------
-10 | -0.00449867
-8 | 0.000384331
-6 | 0.0101503
-4 | 0.0296823
-2 | 0.0882783
0 | 0.2543
2 | 0.542397
4 | 0.962335
6 | 1.65572
8 | 2.34911
10 | 2.96925
  607   Mon Jun 30 18:36:01 2008 YoichiUpdatePSLMZ alignment again
John, Yoichi

We re-adjusted the MZ alignment. The reason behind this is to make sure that the MZ dark port is not falling at a strange fringe, where it is only dark at the dark port PD. It can happen when the two beams poorly overlap.
We tried both the minimization of the MZ dark PD and the maximization of the MZ transmission at the same time.
We also placed another PD in the MZ dark port at a different distance from the original dark PD and tried to minimize this too.
If the MZ dark port is at a strange fringe, one of the dark PD can be dark where the other one is still bright.
If both of the dark PD get dark, the overlap between the beams should be ok.
We tweaked only the two mirrors of the MZ after the EOMs (mainly the one with a PZT).

Right now, the MZ dark power is 0.432.
BTW, we should change the name of the MZ dark port on the medm screen (it is now MZ reflection, where it is not a reflection).
I will try to change it later.

We wanted to put the beam position on the IOO-QPD_POS_* back to the original (before John tweaked the MZ alignment earlier).
However, the trends of IOO-QPD_POS_* show a lot of fluctuation and jumps, of which we don't know the cause. So we could not find reasonable original values.
We suspect a circuit problem in IOO-QPD_POS, especially because the jumps are very strange.
We will do this investigation later too.
  608   Tue Jul 1 09:26:33 2008 steveUpdateComputersRFM network is down
  609   Tue Jul 1 10:15:22 2008 steveUpdatePSLeventfull two days
The laser recovered from a short temp rise. The MZ was aligned and realigned. The suspentions were kicked up accidentally.
Now the computers are down.
Attachment 1: 2d.jpg
2d.jpg
  610   Tue Jul 1 11:53:38 2008 YoichiUpdateComputersRFM network back
I took a tour of the FE machines and power cycled all of them.
After executing the software restart procedures of those computers, the RFM network got back to the normal state.
For some reason, the computers requiring startup.cmd (like c1lsc) halt after running this command. Actually the computer is running ok, but the command freezes. Basically, what it does is simply to load a kernel module. I don't know what is wrong.
Anyway, I just closed the terminal after running startup.cmd and it seems fine for now.
  614   Tue Jul 1 13:34:29 2008 robUpdateComputersRFM network back

Quote:

For some reason, the computers requiring startup.cmd (like c1lsc) halt after running this command. Actually the computer is running ok, but the command freezes. Basically, what it does is simply to load a kernel module. I don't know what is wrong.
Anyway, I just closed the terminal after running startup.cmd and it seems fine for now.


This is normal. On the linux RTFEs (Real-Time Front Ends), the real-time code totally hijacks the kernel, disallowing any interrupts. The system thus becomes totally unresponsive while the code is running, and communicates only through the RFM and the VME backplane.
  618   Tue Jul 1 21:45:48 2008 JohnUpdatePSLMach Zehnder script and screen
I've edited C1: PSL_MACH_ZEHNDER.adl and /cvs/cds/caltech/scripts/PSL/MZ/lockMZ
to reflect the changes described in entry #616.
  619   Tue Jul 1 21:54:05 2008 KojiUpdateGeneralRe: Abs. Length Meas. setup
I tried to look for the beating in the signal from the PD but I couldn't find. I had the temperature of the laser initially set to 40deg and then slowly increased by one degree. The manual of the laser says the frequency should change by several GHz. The problem is then that our PD is limited to no more than 30Mhz.

Although the two beams seem to overlap quite well, we might still need a better matching of the injected beam.


Alberto


Quote:
o The position of the iris was adjusted so as not to disturub the beam for OMCR CCD.

o The RF spectrum analyzer was returned to the place of the network analyzer.


Quote:

In the process of making this report, I noticed that one of the iris apertures is about disturbing the beam for OMCR CCD. I will check this before I go to Hanford. Also an RF spectrum analyzer is at the AP table. I try to return this near the PSL on Monday morning.
  620   Wed Jul 2 00:59:13 2008 MashaUpdateAuxiliary lockingbalanced detection, noise plots, progress
Progress report submitted today(!). It is on the 40m wiki page. Below is a figure of some estimated noise sources.

Made voltage divider that acts as an attenuator for one of the paths in the Mach Zehnder, which should help to balance the detection and reduce noise.

First tested using a 636 Hz Matlab generated audio signal (thanks to John inspiration on portable headphones). Figure is attached, with plots of noise spectra of original and optimized signal with and without added acoustic noise (visible as peaks as 636 and 1272 Hz, linewidth approx 4 Hz). My first try at optimization reduces the noise by nearly an order of magnitude for most frequencies.

Will work on finding different noise source to better see what happens at low frequency, and try to get finer control of tunable gain.
Attachment 1: noise_sources.pdf
noise_sources.pdf
Attachment 2: balancing_detectors.png
balancing_detectors.png
  623   Wed Jul 2 13:56:10 2008 Rob, Yoichi, JohnUpdateLocking24.5 Hz resonance
Work continues on trying to reduce the CARM offset using dc signals from PO_DC. Got up to arm powers of
~35 last night.

We found that progress was stymied by an oscillation around 24 Hz. This oscillation was clearly visible
in the intensity of the light at REFL, PO and TrX.

Initially we suspected that this oscillation was due to an instability in the CARM loop. We attempted to
solve the problem by tuning the crossover frequncy of the AO and MC_L paths and shaping the MC_L loop to
reduce the impact of the 24 Hz noise.

After some quick tests we found that the 24 Hz signal was present even when dc CARM was used. It appears
that the peak is in fact due to a SOS mechanical resonance. We currently suspect a roll mode.

We're going to check that PRC, MICH and DARM have filters to attenuate the 24 Hz line. We'll also look at the
SUS_POS bandstop filters to see where they are centred.

The ISS was behaving strangely again. Constantly saturated at 5dB of gain. Someone needs to look a this.
Attachment 1: locking080702.png
locking080702.png
  624   Wed Jul 2 15:14:42 2008 steveUpdateGeneraladded beam traps
I placed baked razor beam trap after INJ_SM1 and flipper in the injection path on the AP table


Quote:
I have constructed the beam injection optics for the abs length measurement.

The injection beam was coarsely aligned to the interferometer. The reflected beam from SRM was already seen at AS CCD.
I have attached the optical configration for this measurement and the optics layout at the AP table.

I am going to go to LHO for three weeks. During the absence Alberto tunes the mode matching and the alignment of the interferometer.

In the process of making this report, I noticed that one of the iris apertures is about disturbing the beam for OMCR CCD. I will check this before I go to Hanford. Also an RF spectrum analyzer is at the AP table. I try to return this near the PSL on Monday morning.

Attachment 1: Optical configuration for the abs length measurement.
1) One of the arms is locked to the PSL beam by the main control system (red).
2) A laser beam is injected from the AS port (blue). This laser essentially has different frequency from that of PSL.
3) The injected beam and the outgoing PSL beam appear at the output of the faraday in the injection system.
4) They beat each other at the frequency difference of those two lasers.
5) A PLL is used to lock the frequency difference to a local oscillator (LO).
6) The LO frequency is swept at around 3.87MHz, that is the approximate FSR frequency of the arm cavity.
7) If the LO frequency hits the FSR within the resonant width, the beating also appears at the transmitted light as the injected beam also becomes resonant to the arm cavity.
8) Amplitude of the beating at the transmitted light is measured by a RF spectrum analyzer as a function of the LO frequency. We get the FSR frequency (= the arm cavity length) from the top of the resonance.

Attachment 2: Optics at the AP table for the laser injection
700mW NPRO, laser source. vertically polarized.
Periscope, to raise the beam 1 inch to make the beam at the 4 inch elevation.
INJ_SM1/INJ_SM2, steering mirrors to align the injection beam to the IFO beam.
HWP1, half wave plate to make the beam to the farady horiz-polarized. nominal 42deg on the readout.
FI, Faraday isolator for protection of the NPRO from the returning light, for obtaining the returning light.
HWP2, to make the beam from the Faraday horiz-polarized. nominal 357deg on the readout.
MM_Lens, f=125mm to match the laser mode to the IFO beam.
SM1/SM2, steering mirrors to align the IFO beam to the Farady Isolator.
IRIS1/IRIS2, for the coarse alignment of the injection beam.
FLIP, flipper mount to turn on/off the injection optics.

Alignment procedure of the injection system
0) Ignite NPRO several hours before the experiment so that the laser frequency can be stable.
1) Turn up FLIP. Close the shutter of NPRO.
2) Adjust SM1/SM2 so that the ifo beam can appear at the output of FI.
3) Adjust height and position of IRIS1/IRIS2 with regard to the ifo beam so that the ifo beam goes through IRIS1/IRIS2 even when they are closed.
4) Turn down FLIP. Open the shutter of NPRO.
5) Adjust INJ_SM1/INJ_SM2 so that the injection beam can go through IRIS1/IRIS2 even when they are closed.
6) At this time, it is expected that the reflection of the injection beam from SRM appears at AS CCD, if SRM is aligned.
7) Adjust INJ_SM1/INJ_SM2 so that the injection beam at AS CCD can overlap to the IFO beam.
8) Confirm the beam at the output of the FI also overlaps.
---- We are here ----
9) Change the ifo configuration to the X or Y arm only.
10) Scan the crystal temperature of the 700mW NPRO in order to try to have the beating of the two beams at the PD. AS OSA may be useful to obtain the beating.
11) Once the beating is obtained, adjust INJ_SM1/INJ_SM2 such that the beating amplitude is maximized.
  626   Wed Jul 2 18:30:01 2008 JohnUpdateIOOQPD alignment
I aligned the beams on the following QPDs

IP POS
IP ANG
MC TRANS
IOO POS
Attachment 1: IOO080702.png
IOO080702.png
Attachment 2: MC080702.png
MC080702.png
  627   Wed Jul 2 19:15:52 2008 AlbertoUpdateGeneralStatus of the alignment of the NPRO beam for the Absolute Length Measurement
Today I've tried to bring the frequency of the NPRO laser close enough to that of the IFO beam so that the beat between the two beams can be at a detectable frequency for the photodiode. The way I've been changing the frequency is by the NPRO's temperature control on its driver.

Looking at the signal from the AS OSA should enable us to monitor the direction in which the frequency is changing. Every time the resonances of the IFO beam and of the NPRO beam overlap, we know that the frequencies of the two beams are some FSR of the OSA away from each other. At the overlapping of the resonances, if the difference of frequency is within the detectable range of the photodiode, we should see a peak in the network/spectrum analyzer.

This way turned out not very easy in practice because from the AS OSA one can hardly distinguish the resonances of the primary beam from those of the secondary beam. The cause is mainly the flashing of the IFO beam at the AS port which produces a pattern of resonances of different amplitude. Also for some reason, triggering the output signal from the OSA at the oscilloscope doesn't work very well.

However, even if we didn't have these problems, I think that the two beams are not very well aligned, at least not anymore. I'm attaching some pictures from the AS port. The bright spot on the left is the NPRO beam and the one in the center which flashes is the IFO beam. We probably need some more work in the alignment of the NRPO beam.
Attachment 1: DSC_0156.JPG
DSC_0156.JPG
Attachment 2: DSC_0158.JPG
DSC_0158.JPG
  628   Thu Jul 3 11:53:30 2008 KojiUpdateGeneralStatus of the alignment of the NPRO beam for the Absolute Length Measurement
The method itself looked fine.

Use of the one arm configuration will make the work easier as constant power at the AS port is obtained.
How much is the FSR of the OSA?

Apparently the alignment is not good any more as Alberto pointed. Everytime you touch the flipper you'd better to adjust it. Then, if necessary, adjust the injection steerings.

If the PSL beam is blocked, only the injection beam appears at the optical ports. The spot is obtained at the AS port and the SY port (REFL) at the same time. I recommend to confirm the transmittion to the SY port too by the CDD, the card, and whatever. Note that this may be difficult because this will have the beam power of below 1 mW.


Quote:
Alberto> Today I've tried to bring the frequency of the NPRO laser ...
  630   Thu Jul 3 13:12:32 2008 Rob, Yoichi, JohnUpdateLockingMore oscillations
Bounce/ roll filters were added to the short degrees of freedom to reduce the effect of the 24Hz line seen on Tuesday night.

However last night saw the arrival of a new oscillation at ~34Hz. This may be the second harmonic of the MOS roll mode. Reducing the arm offset would cause this oscillation to ring up and break the lock (first plot). This effect was repeatable.

No signal was seen in the oplevs or osems which leads us to rule out alignment problems, at least for now.

Although one can clearly see DARM_ERR increasing as arm power increases adding a resonant gain in the DARM loop had no effect.

We also noticed that x arm transmission was significantly more noisy than the Y (second plot). And showed greater coherence with the increase in DARM noise. Investigations showed that the PD was not the source of the difference.

Turning up the MC gain seems to help a little.

We're now looking at POX as a candidate for RF_CARM (third plot).
Attachment 1: LOL.png
LOL.png
Attachment 2: NoisyX080702.png
NoisyX080702.png
Attachment 3: POXforCARM080702.png
POXforCARM080702.png
  634   Thu Jul 3 18:48:09 2008 AlbertoUpdateGeneralBeats of the two lasers in the absolute length measurement observed
I adjusted the alignment of the flipper mirror as suggested by Koji making the two beam spots match. I also aligned all the IFO mirrors (ITMs, PRM, SRM, ETMs) to have more power for the IFO signal at the AS port. When I did that I could see the beats at the AS OSA. Then I explored the range of temperature of the NPRO from 35deg (C) to 51.2807deg and at that point I could observe a peak corresponding to the beat at about 10MHz on the network analyzer. The peak tends to drift because the laser takes probably a longer time to actually thermalize and it moves very rapidly changing the temperature of the laser.
  635   Thu Jul 3 22:54:45 2008 KojiUpdateGeneralBeats of the two lasers in the absolute length measurement observed
Great! Conguraturation! I wish if I could see it! It's nice if you can put the photo or anything of the RF spectrum analyzer.

Next step:
o You can try to maximize the beat amplitude by the tuning of the Injection steering mirrors.

o At the south end of the SP table, I prepared a frequency mixer. You can put the beat signal into the RF input, and an oscillator (which you can bring from somewhere) to the LO input in order to obtain the error signal of the PLL. Put the IF output of the mixer in a SR560, and please try to lock it by a simple 6db/oct (1st order) LPF of the SR560. For the actuator you can use the fast-pzt input of the NPRO.


Quote:
Then I explored the range of temperature of the NPRO from 35deg (C) to 51.2807deg and at that point I could observe a peak corresponding to the beat at about 10MHz on the network analyzer.
  637   Mon Jul 7 11:22:02 2008 AlbertoUpdateGeneralBeats of the two lasers in the absolute length measurement observed
I didn't post a screenshot from the RF SA because I had troubles with the interface with the computer (unfortunately the network SA cannot export the data either).

There is problem with the PLL circuit. The signal, beside the beat, also contains peaks at 33, 66 and 99 MHz, so we should think about filtering those out.


Quote:
Great! Conguraturation! I wish if I could see it! It's nice if you can put the photo or anything of the RF spectrum analyzer.

Next step:
o You can try to maximize the beat amplitude by the tuning of the Injection steering mirrors.

o At the south end of the SP table, I prepared a frequency mixer. You can put the beat signal into the RF input, and an oscillator (which you can bring from somewhere) to the LO input in order to obtain the error signal of the PLL. Put the IF output of the mixer in a SR560, and please try to lock it by a simple 6db/oct (1st order) LPF of the SR560. For the actuator you can use the fast-pzt input of the NPRO.


Quote:
Then I explored the range of temperature of the NPRO from 35deg (C) to 51.2807deg and at that point I could observe a peak corresponding to the beat at about 10MHz on the network analyzer.
  638   Mon Jul 7 13:06:38 2008 KojiUpdateGeneralBeats of the two lasers in the absolute length measurement observed
One may need an RF filter after the mixer. I expect the SR560 does work for this purpose.
If it does not, a passive LPF can be used.


Quote:
I didn't post a screenshot from the RF SA because I had troubles with the interface with the computer (unfortunately the network SA cannot export the data).

There's is problem with the PLL circuit. The signal, beside the beat, also contains peaks at 33, 66 and 99 MHz, so we should think about filtering those out, correct?
  641   Mon Jul 7 14:02:05 2008 YoichiUpdateComputersSVN conversion progress
So far /cvs/cds/caltech/medm, /cvs/cds/caltech/chans and /cvs/cds/caltech/scripts have been converted to svn working copies.
Now /cvs/cds/caltech/target is being converted.
  642   Mon Jul 7 16:30:08 2008 steveUpdatePSLPSL-PEM 16 days trend
This morning the laser head temp was up to 20.3C because the laser chiller was overflowing.
I removed 700 cc water.

The PSL-FSS_RMTEMP became much more stable during the holidays as the psl enclosure was closed for 4 days

The high particle counts can be explaned by construction activity today.

The PMC & MZ PZT high voltages were out of range this morning.
Attachment 1: pempsl16d.jpg
pempsl16d.jpg
  643   Mon Jul 7 19:15:38 2008 AlbertoUpdateGeneralOptics alignement on the ABS length experiment
Today I started setting up the PLL instruments to lock the frequency of the NPRO beam to the IFO beam. with no need of a new alignment after the weekend I was able to see the beat again, although this time I found at a different temperature of the NPRO laser of about 54 degrees (vs 51 of the last time).
I've got the Marconi as local oscillator (LO), the mixer Koji suggetsed, the SR560 and a 5 MHz low pass filter to cut the 33, 66 and 99 MHz present in the output signal from the PD. The filter worked well and I was able to single out only the beat resonance from the power spectrum.
In the attempt to enhance the amplitude of the beat, as Koji suggested, I tried to work on the alignment of the steering mirrors. While I was doing that, for some reason the pre-modecleaner lost the alignment and I had to ask John to help me lock it again. during the process I lost the old alignment but at the end I got a new one, apparently (from the camera) even better than the other. Although after that the beats were gone. Actually after the lock-in of the PMC the IFO beam didn't look as good as before, so it might be also for that reason.

I'll try again tomorrow, after that probably tonight Rob is going to reset the alignments of the interferometers.
  645   Tue Jul 8 08:16:56 2008 steveUpdatePSLPMC problem
The PMC is unhappy. PMC auto locker is not working.
DC output slider adjust has to be moved from rail to rail before it locks.

MZ is working great.
Attachment 1: pmc.jpg
pmc.jpg
  646   Tue Jul 8 10:20:10 2008 steveUpdatePEMHEPA turned on
It is specially important to run the PSL-HEPA filters when inside counts is peaking at 30,000 counts

There is a small label at the hepa on/off switch:
enclosure open 100%,
low noise off,
normal 60% of Variac voltage setting on the top of the enclosure

Not running the HEPAs will lower the temp fluctuations from 1.5 to o.5 degree C
at the cost of particle counts from 0 to immidiate room counts.
Attachment 1: hepa.jpg
hepa.jpg
  647   Tue Jul 8 10:26:30 2008 MashaUpdateAuxiliary lockingsetup updates
Yesterday I changed one of the beam splitters in the Mach Zehnder to one with a more stable mount as to reduce the system's coupling to environmental noise.

With help from John, I worked out how to get the signals from the two channels of the interferometer into the digital system. I put up BNC cables along part of the Y arm to connect the output of the detectors into the digital channels.
  650   Tue Jul 8 21:58:22 2008 albertoUpdateGeneralSecondaty beam aligned to the IFO beam again
Yesterday the alignment of the secondary beam to the IFO was completely lost and today I had to realign all the optics before I was able to match the two spots again. I had to reset the height of the irises and I had also to replace mirror M1 with one with a larger angular motion. Eventually I obtained the beat again. Working on the optics table I inadvertently misaligned the OSA but I didn't make in time to bring it back before the night shift people came. I'll work on that tomorrow morning.
  651   Wed Jul 9 12:42:14 2008 JohnUpdateLockingHand off to RF CARM
Rob, Yoichi, John

Last night we were able to reduce the CARM offset to around 80. This was achieved by increasing the DARM gain and
switching to AS_I when AS_Q went bad. This is probably a temporary solution, we will probably switch to DC readout
for DARM as we bring the arms on resonance.

Having reduced the arm offset enough to get us into the linear region of the RF_CARM signal (POX_I) we worked on
analogue conditioning of this signal to allow us to hand over. Lock was maintained for over 20 minutes as we did
this work.

We were able to partially switch over both the frequency and length paths to this new signal before losing lock.
Attachment 1: LongLock080709.png
LongLock080709.png
  655   Thu Jul 10 14:59:01 2008 robUpdateLockingRF common mode at zero offset
rob, john, yoichi

Last night we succeeded in reducing the CARM offset to zero.

We handed off control of the common mode servo from PO-DC to POX-I.

We pushed the common mode servo bandwidth to ~19kHz. Without the boosts, it had ~80 degs of phase margin. Didn't measure it after engaging the boosts (Boost + 1 superboost). Trying to engage the second superboost stage broke the lock.

The process is fully scripted, and the script worked all the way through several times.

The DARM ugf was ~200Hz. The RSE peak could clearly be seen. No optical spring, as expected (we're locking in anti-spring mode).

Engaging test mass de-whitening filters did not work (broke the lock).

I'm attaching a lock control sequence diagram and a trend of the arm power during a scripted up-sequence. I think the script can be sped up significantly (especially the long ramp period).

Up next:

Calibrated DARM spectrum
Noise hunting (start with dewhites)
DC - Readout
Lock to the springy side.
Attachment 1: lock_control_sequence_worked.png
lock_control_sequence_worked.png
Attachment 2: trendpowerbuild.png
trendpowerbuild.png
  656   Thu Jul 10 19:12:07 2008 AlbertoUpdateGeneralabs cavity length measurement experiment
Yesterday morning, when I started, I found the IFO beam on a different position and the beam spot at the AS port looked very deformed. The overlapping with the secondary beam was not good enough to observe the beats anymore. Restoring the alignments of the interferometers did not work because, as John found out later, some of the photodiodes had offsets and gain which made the restore script ineffective. After resetting the parameters, we had to align every mirror of the interferometers and save the configuration twice. The second times was because on the first time the alignment had been done with the illuminators on. To avoid that in the future, John wrote an alarm to warn about the status of the lights.

After that we fixed the IFO beam, I had to realign the optics in the table to match the secondary beam to the IFO beam. I got the two beam overlapping and, even though the NPRO spot looked distorted, I could observe again some signal of the beat. To do that it was also necessary to have all the interferometer mirrors aligned so that we had more power from the ifo beam although it also made the spot flash. Ideally, to avoid the flashing (which we would also impede the PLL to work) we should work with the interferometer locked. Since that doesn't seem actually possible, we should just keep one of the ITM aligned and improve the beam matching so that we can observe the beats even with less power.

Today I spent the day trying to improve the alignement of the optics to observe the beats with only the ITM aligned, resetting the alignment of both beams with the ireses, with the Farady and all the rest. It was a rather long and tiring process but I think I'm close to the target and maybe tomorrow.
  659   Fri Jul 11 09:29:02 2008 steveUpdatePSLthe PMC still hangs up
Morning alarms:

PMC high voltage is railing, it's auto locker is frosen
I have to move DC Output Adjust slider by hand and it locks immediately

PSL_ISS is saturating. Saturation goes away when PMC is locked.

Laser chiller water is overflowing again: removed 450 cc water
Attachment 1: pmc4d.jpg
pmc4d.jpg
  661   Fri Jul 11 23:55:25 2008 alanUpdateLockingRF common mode at zero offset

Quote:
rob, john, yoichi

Last night we succeeded in reducing the CARM offset to zero.



Congratulations! Well done! I look forward to hearing the details and further progress!
  662   Sat Jul 12 23:28:31 2008 ranaUpdatePSLPMC needs help
As everyone has noticed recently, the PMC seems to have a PZT problem. It often zooms
of to one of its rails after locking as if the PZT range has decreased dramatically.

WE should check this on Monday by disabling the FSS and applying a slow triangle wave to
the NPRO frequency. The PMC will track this frequency change and this will allow us to
diagnose its problems.

If it has real problems, I have a spare in W. Bridge which we can swap in temporarily.

The attached plot shows 3 years of trend; looks like it went bad in summer of last year.

This also seems to be the cause of our ISS saturation problems: lowering the gain of the PMC
even slightly increased the intensity noise enough to cause saturation. Increasing the gain
even slightly increased the intensity noise enough to cause saturation due to PMC servo oscillation.
Attachment 1: Untitled.png
Untitled.png
  668   Mon Jul 14 19:15:43 2008 AlbertoUpdateGeneralabs cavity length measurement experiment
Lately I've been dealing with the alignment of the interferometer to have a good beam spot at the AS port. Today the alignment script kept failing because of computer problems (failure of the frame builder) and also because the IFO was probably too far from the range where the automatic alignment works.

An other problem I keep having with the alignment of the optics on the AP table is with multiple reflection beams of the NPRO beam at the Farady.
Although I believe that now the two beams are quite well aligned, I don't see any reflection of the secondary beam from the IFO anymore.

It's like the more I try to improve the alignment, the worse I get from the beam matching. I'll keep working on this.
  669   Mon Jul 14 21:34:10 2008 AlbertoUpdateGeneralabs cavity length measurement experiment

Quote:
Lately I've been dealing with the alignment of the interferometer to have a good beam spot at the AS port. Today the alignment script kept failing because of computer problems (failure of the frame builder) and also because the IFO was probably too far from the range where the automatic alignment works.

An other problem I keep having with the alignment of the optics on the AP table is with multiple reflection beams of the NPRO beam at the Farady.
Although I believe that now the two beams are quite well aligned, I don't see any reflection of the secondary beam from the IFO anymore.

It's like the more I try to improve the alignment, the worse I get from the beam matching. I'll keep working on this.


Realigning the OSA I also had to move a little bit the mirror that reflects the IFO beam of at the AS port in order to raise the beam height. This had the effect of changing the position of the AS spot on the camera and on the monitors.

Tonight with John, we made sure that the AS beam was still aligned to the PD.
  670   Tue Jul 15 09:47:09 2008 steveUpdatePEMlab temps and particles
All air condtion units were serviced last Friday.
AC filters are trying to control our particle counts but they have no capacity to match bad Pasadena conditions.
IFO room filters at CES were really clean.
Air make up filters inside and outside were dirty.
They showed the construction effect.
Control room and clean assembly units needed all filters replaced.

Note: the PSL-FSS_RCTEMP droped o.1C when enclouser HEPAs were turned back on
The RC temp controller should be better than that!
Attachment 1: temps24d.jpg
temps24d.jpg
  672   Tue Jul 15 10:24:57 2008 steveUpdatePSLPMC temp & pzt voltage
The PMC pzt HV was happy with no HEPA temp stability.
Can we thermally insulate the pmc ?
Attachment 1: pmctemp.jpg
pmctemp.jpg
  674   Tue Jul 15 12:23:22 2008 JenneUpdateGeneralMC2 Watchdog tripped
Alberto, Jenne

Mode Cleaner was unlocked. We checked, and found that MC2's watchdog was tripped. It didn't look like anything bad was going on, so we turned the optic back on, and tried to relock the MC. It looks like the Mode Cleaner is now locked, but the lock bit on the LockMC screen is still red. I don't know what's up.
ELOG V3.1.3-