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ID Date Author Type Category Subjectup
  12918   Thu Mar 30 00:16:09 2017 gautamUpdatePSLPSL NPRO PZT calibration

As part of the ongoing effort to try and calibrate the PMC DAQ channels into physical units, I tried to get a calibration for the PSL NPRO PZT actuator gain. In order to do this, I selected "Blank" on the PMC servo MEDM screen such that there was no feedback signal to the PMC PZT for length control. Then I used the summing box right before the  PSL PZT to inject a ~1Hz triangular wave, 4Vpp. This was sufficient to sweep the NPRO frequency over 70MHz such that both sidebands and the carrier go through resonances in the PMC cavity. I then simultaneously monitored the applied triangular wave voltage and the PMC error signal (using the single pin LEMO connector on the front panel) on an oscilloscope. Analysis is underway, but a quick look at one measurement suggests a PZT actuator gain of ~1.44MHz/V, which is close to what we expect for the Innolight NPROs. The idea is to use this calibration to convert the DQ channels into physical units. 

Details + plots + error analysis to follow...

  12925   Mon Apr 3 17:25:13 2017 gautamUpdatePSLPSL NPRO PZT calibration

Summary:

By sweeping the laser frequency and looking at the PMC PDH error signal, I have determined the 2W Mephisto Innolight PZT actuator gain to be 1.47 +/- 0.04 MHz/V

Method:

  1. Re-aligned the input beam into the PMC to maximize transmission level on the oscilloscope on the PSL table to 0.73V.
  2. Disabled control signal from IMC servo to PSL. 
  3. Unlocked the PMC and disabled the loop by selecting "BLANK" on the PMC MEDM screen.
  4. Connected a 0.381 Hz 5Vpp triangular wave with SR function generator to the "SUM" input of the Fast I/F box just before the PSL PZT input. These params were chosen considering the Pomona box just before the NPRO has a corner at 2.9Hz, and also to sweep the voltage to the NPRO PZT over the full 150V permitted by the Thorlabs HV amplifier unit. Monitored the voltage to the Thorlabs HV amp from the "AFTER SUM" monitor point on the same box. Monitored the PMC PDH error signal using the single-pin LEMO monitor point on the PMC servo board (call this Vmon). Both of these signals were monitored using a Tektronix digital O'scope.
  5. Downloaded the data using ethernet.
  6. Fit a line to the voltage applied to the NPRO PZT - I assumed the actual voltage being applied to the PZT is 15*Vmon, the pre-factor being what the Thorlabs HV amplifier outputs. The zero crossings of the sideband resonances in the PDH error signal are separated by 2*fmod (separated by fmod from the carrier resonance, fmod = 35.5MHz assumed). With this information, the x-axis of the sweeps can be converted to Hz, from which we get the PZT actuator gain in MHz/V. 

An example of the data used to calculate the actuator gain (left), and the spread of the calculated actuator gain (right - error bars calculated assuming 5e-4 s uncertainty in the sideband zero-crossing interval, and using the error in the slope of the linear fit to the sweep voltage):

This will now allow calibration of the PMC DAQ channels into Hz.

GV 4 April - The y-axis of the lower plot in Attachment #1 has mis-labelled units. It should be [V], not [MHz/V].

Attachment 1: PDHerr.pdf
PDHerr.pdf
Attachment 2: NPROcalib.pdf
NPROcalib.pdf
  12928   Tue Apr 4 17:27:58 2017 ranaUpdatePSLPSL NPRO PZT calibration

good cal. I wonder if this data also gives us a good measurement of the cavity pole or if the photo-thermal self-locking effect ruins it. You should look at the data for the positive sweeps and negative sweeps and see if they give the same answer for the cavity poles. Also, maybe we can estimate the PMC cavity pole using the sidebands as well as the carrier and see if they give the same answer? 

  13137   Mon Jul 24 12:00:21 2017 gautamUpdatePSLPSL NPRO mysteriously shut off

Summary:

At around 10:30AM today morning, the PSL mysteriously shut off. Steve and I confirmed that the NPRO controller had the RED "OFF" LED lit up. It is unknown why this happened. We manually turned the NPRO back on and hte PMC has been stably locked for the last hour or so.

Details:

There are so many changes to lab hardware/software that have been happening recently, it's not entirely clear to me what exactly was the problem here. But here are the observations:

  1. Yesterday, when I came into the lab, the MC REFL trace on the wall StripTool was 0 for the full 8 hour history - since we don't have data records, I can't go back further than this. I remember the PMC TRANS and REFL cameras looked normal, but there was no MC REFL spot on the CCD monitors. This is consistent with the PSL operating normally, the PMC being locked, and the PSL shutter being closed. Isn't the emergency vacuum interlock also responsible for automatically closing the PSL shutter? Perhaps if the turbo controller failure happened prior to Jamie/me coming in yesterday, maybe this was just the interlock doing its job. On Friday evening, the PSL shutter was certainly open and the MC REFL spot was visible on the camera. I also confirmed with Jamie that he didn't close the shutter.
  2. Attachment #1 shows the wall StripTool traces from earlier this morning. It looks like ~7.40AM, the MC REFL level went back up. Steve says he didn't manually open the shutter, and in any case, this was before the turbo pump controller failure was diagnosed. So why did the shutter open again
  3. When I came in at ~10AM, the CCD monitor showed that the PMC was locked, and the MC REFL spot was visible. 
  4. Also on attachment #1, there is a ~10min dip in the MC REFL level. This corresponds to ~10:30AM this morning. Both Steve and I were sitting in the control room at this time. We noticed that the PMC TRANS and REFL CCDs were dark. When we went in to check on the laser, we saw that it was indeed off. There was no one inside the lab area at this time to our knowledge, and as far as I know, the only direct emergency shutoff for the PSL is on the North-West corner of the PSL enclosure. So it is unclear why the laser just suddenly went off.

Steve says that this kind of behaviour is characteristic of a power glitch/surge, but nothing else seems to have been affected (I confirmed that the X and Y end lasers are ON). 

Attachment 1: IMG_7454.JPG
IMG_7454.JPG
  15642   Fri Oct 23 19:01:57 2020 KojiSummaryPEMPSL Particle Counter kit removed from the table

The particle counter on the 40m PSL was removed. The package was made together with the OMC lab particle counter (see the packing list below).

The kit was picked up by Radhika for a python code to read out the numbers.

=== Packing List ===

  • MET ONE 227A particle counter
    • used at the 40m. It has the particle reading and the temperature reading.
  • Power supply adapter (AC/DC) for 227A
    • Caution: It is not compatible with GT-321.
  • MET ONE GT-321
    • I found another type of particle counter in West Bridge.
  • Power supply adapter (AC/DC) for GT-321. (Labeled "for GT-321")
    • Caution: It is not compatible with 227A.
  • DB9 cable for GT-321
  • Air Filter G3111
    • When you run a particle counter attach this filter instead of the dust collecting cup to keep the air in take of the particle counter clean. This should keep the particle level down to zero.
       
Attachment 1: P_20201022_173529.jpg
P_20201022_173529.jpg
Attachment 2: P_20201022_173419.jpg
P_20201022_173419.jpg
  7070   Wed Aug 1 15:14:20 2012 JenneUpdateIOOPSL Pointing QPD signals lost in late-June 2012

I was looking into why we don't have any light on the PSL pointing QPDs, and it turns out that it has been this way since ~June 29th 2012.  I need to look back in the elog to see what was going on on the PSL table that day, but I suspect it has something to do with Yuta and I, working on the beat setup, since this is all very near that area.

Attached is a plot of the loss of signal on the QPDs.

UPDATE:

 We lost IP POS on the same day as we lost the PSL pointing.  See 2nd attachment.  The _S_Calc is the sum, and it almost looks like the light got near the edge of the diode and just kept falling off until it was gone.  The sum started getting lower on May 16th, and then was gone on June 29th.

So far I've gone back as far as Jan 2012, but I still haven't found any data where we *did* have light on IP ANG.  Sad.

UPDATE, UPDATE (like P.P.S.):  June 29th was the day of the vent...see elog 6895.

Attachment 1: IOO_QPDs_lost_midJune2012.png
IOO_QPDs_lost_midJune2012.png
Attachment 2: IP_QPDs_lost_midJune2012.png
IP_QPDs_lost_midJune2012.png
  778   Fri Aug 1 01:13:32 2008 ranaConfigurationPSLPSL Quad change and new script
Koji and I changed a few optics so that now ~60% of the beam that went to the PSL POS QPD
now goes to the west side of the table for the aux. laser locking PLL. The beam is sort of
on the QPD again but needs a centering.

After this work I wrote a script SUS/freeswing-all.csh which puts a 30000 count offset into
the UL coil of each suspension and then disables it. This is just good enough to kick it up
so that the eigenfrequency can be measured. I ran it and it worked -- it finished running at

Fri Aug 1 00:44:30 PDT 2008
  781   Fri Aug 1 16:33:52 2008 ranaConfigurationPSLPSL Quad change and new script
Here's the sensor ringdown trend from the kick.
Attachment 1: Untitled.png
Untitled.png
  15243   Tue Mar 3 17:59:33 2020 YehonathanUpdateElectronicsPSL Shutter and PMC TRANSPD working

I used existing BNC cables running from the PSL table to the PSL rack and reassigned them to the PSL Shutter and PMC transmission PD channels.

The PSL shutter turned out to be a sinking channel. Jordan reconnected the PSL shutter wires to a sinking BIO Acromag. Channel list is updated.

Both channels have been tested to be working as expected.


gautam add on about EPICS:

  • the PSL shutter channels were previously hosted on c1aux.
  • I didn't comment out the original database entries on c1aux because we changed the prefix for all these channels - i.e. C1:AUX-PSL_Shutter --> C1:PSL-PSL_Shutter.
  • Modified the LSC offset script to close/open the PSL shutter by writing to the correct channel now.
  • there is some EPICS logic that checks the main volume pressure and prevents the opening of the PSL shutter if the main volume pressure is between 0.003 torr and 500 torr. I preserved this capability (so there are some associated soft channels in the database as well).

P.S - there is a problem we noticed - if the modbus process is started with the local subnet not having a fixed IP address, then all the EPICS channels will not be responsive. The way to fix this is to run the following sequence of commands:

sudo systemctl stop modbusIOC.service
sudo ifdown enp4s0
sudo ifup enp4s1
sudo ssytemctl start modbusIOC.service
  15255   Thu Mar 5 15:03:48 2020 YehonathanUpdateElectronicsPSL Shutter and PMC TRANSPD working

[Jon, Yehonathan]

Summary

With the Acromag chassis now permanently installed, we tested the C1PSL channels going over the channel list one by one, excluding the IMC channels which Gautam is taking responsibility for (the servo board itself is also in question).

The strategy is to check the response of input channels to specific output channels for expected behaviour whenever is possible.

We marked on the channel list spreadsheet the status of the channels that were tested.

In more detail

FSS

Channels under test What was done
C1:PSL-FSS_SW1 Switched C1:PSL-FSS_SW1 and observed the IMC unlock
C1:PSL-FSS_SW2, C1:PSL-FSS_MIXERM Connected a signal to Test2 on FSS box and observed a proportional change on C1:PSL-FSS_MIXERM
C1:PSL-FSS_INOFFSET Disconnected feedback by switching C1:PSL-FSS_SW1. Tweaked C1:PSL-FSS_INOFFSET and observed a proportional response in C1:PSL-FSS_MIXERM
C1:PSL-FSS_MGAIN, C1:PSL-FSS_PCDRIVE Disconnected feedback, turned on some offset using C1:PSL-FSS_INOFFSET. Tweaked C1:PSL-FSS_MGAIN and observed a response in C1:PSL-FSS_PCDRIVE
C1:PSL-FSS_SLOWDC, C1:PSL-FSS_SLOWM Disconnected feedback. Tweaked C1:PSL-FSS_SLOWDC and obsereved a proportional response in C1:PSL-FSS_SLOWM
C1:PSL-FSS_FASTGAIN, C1:PSL-FSS_FAST Disconnected feedback, turned on some offset using C1:PSL-FSS_INOFFSET. Tweaked C1:PSL-FSS_FASTGAIN and obsereved a response in  C1:PSL-FSS_FAST

 

Frequency Ref

Channels under test What was done
C1:PSL-PMC_PHCON Observed the PMC unlocks when a big change in C1: PSL-PMC_PHCON is made
C1:PSL-PMC_RFADJ, C1:PSL-PMC_MODET Tweaked C1:PSL-PMC_RFADJ and obsereved a proportional response in C1:PSL-PMC_MODET
C1:PSL-PMC_PHFLIP Observed the PMC unlock when C1:PSL-PMC_PHFLIP is switched

 

PMC Servo Card

Channels under test What was done
C1:PSL-PMC_SW1, C1:PSL-PMC_PMCERR, C1:PSL-PMC_INOFFSET, C1:PSL-PMC_PZT Unlocked the PMC by switching C1:PSL-PMC_SW1. Tweaked C1:PSL-PMC_INOFFSET and observed a proportional change in C1:PSL-PMC_PMCERR and C1:PSL-PMC_PZT
C1:PSL-PMC_BLANK Observed the PMC unlock with when C1:PSL-PMC_BLANK is switched
C1:PSL-PMC_GAIN Unlocked the PMC by switching C1:PSL-PMC_SW1. Turned on some offset using  C1:PSL-PMC_INOFFSET. Tweaked C1:PSL-PMC_GAIN and observed response in C1:PSL-PMC_PZT
C1:PSL-PMC_SW2 Unlocked the PMC by switching C1:PSL-PMC_SW1. Connected a signal to TP2 on the PMC card and observed a proportional change in C1:PSL-PMC_PZT.
C1:PSL-PMC_RAMP

Unlocked the PMC by switching C1:PSL-PMC_SW1. Tweaked C1:PSL-PMC_RAMP and observed a change in C1:PSL-PMC_PZT.

C1:PSL-PMC_RFPDDC Observed a high value 0.5V when PMC is unlocked and a low value 0.03V when it is locked

 

WFSs

Channels under test What was done
C1:IOO-WFS*_SEG*_ATTEN

We misaligned MC1 to get a measurable signal in WFS channels. NDScoped the corresponding C1:IOO-WFS*_SEG*_I&Q channels and observed a change in those channels in response to switching the attenuation on and off.

C1:IOO-WFS*_LO_LOCK_MON Disconnected the LO cable from the WFS boards and observed C1:IOO-WFS*_LO_LOCK_MON go to zero.
C1:IOO-WFS*_SEG*_I&Q Connected a short SMA cable to the 29.5MHz frequency distribution board. Attenuated the signal by 20db and connected it to the different SEG channels one at a time and observed a response in C1:IOO-WFS*_SEG*_I&Q channels.
C1:IOO-WFS*_SEG*_DC We shined a laser pointer to the different quadrants and observed saturation in the corresponding C1:IOO-WFS*_SEG*_DC with no cross talks.

MC Servo

Channels under test What was done
C1:IOO-MC_SW1, C1:IOO-MC_OPTIONA, C1:IOO-MC_POL, C1:IOO-MC_OPTIONB,C1:IOO-MC_FASTSW These switches unlocked the IMC when flipped.
C1:IOO-MC_SW2, C1:IOO-MC_SUM_MON, C1:IOO-MC_SLOW_MON, C1:IOO-MC_FAST_MON A sine wave signal was injected in IN2 on the servo board. C1:IOO-MC_SW2 was switched on and the value of C1:IOO-MC_SUM_MON, C1:IOO-MC_SLOW_MON and C1:IOO-MC_FAST_MON changed accordingly.
C1:IOO-MC_SW3 Connected a scope to OUT2 on the servo board. Switched C1:IOO-MC_SW3 on and observed a signal on the scope.
C1:IOO-MC_EXCA_EN Unlocked the IMC by switching C1:IOO-MC_SW1 off. Connected a signal to EXC A and a scope to TP2A on the servo board and observed the signal on the scope when C1:IOO-MC_EXCA_EN was switched on.
C1:IOO-MC_EXCB_EN Unlocked the IMC by switching C1:IOO-MC_SW1 off. Connected a signal to EXC B and a scope to TP2B on the servo board and observed the signal on the scope when C1:IOO-MC_EXCB_EN was switched on.
C1:IOO-MC_REFL_OFFSET Unlocked the IMC by switching off. Tweaked C1:IOO-MC_REFL_OFFSET and observed a proportional change in C1:IOO-MC_SUM_MON.
C1:IOO-MC_LATCH_EN Tweaked the VCO gain slider and observed the latch switch off and on.
C1:IOO-MC_LIMIT Unlocked the IMC by switching C1:IOO-MC_SW1 off. Connected a sine wave signal to EXC B and enabled C1:IOO-MC_EXCB_EN. Ramped up the VCO gain. Raised the sine wave amplitude until C1:IOO-MC_LIMIT turned on.
C1:IOO-MC_LIMITER We ramped the VCO such that C1:IOO-MC_LIMIT was switched on. We switched C1:IOO-MC_LIMITER on and observed C1:PSL-FSS_MIXERM high value go down.

NPRO Diagnostics

Channels under test What was done
C1:PSL-NPRO_*

The signals were compared to previous values for consistency. Then they were unplugged from the Acromag chassis to confirm their values went to 0 and returned to the same values after being reconnected.

  6252   Fri Feb 3 19:57:26 2012 ranaConfigurationSUSPSL Shutter closed for SUS hysteresis test

Fri Feb 03 19:57:20 2012

Fri Feb 03 20:25:19 2012 :   Aligned all SUS to center their OL beams

Fri Feb 03 20:29:21 2012:    Aligned all SUS to make OL_PIT = 0.5

  13148   Fri Jul 28 16:47:16 2017 gautamUpdateGeneralPSL StripTool flatlined

About 3.5 hours ago, all the PSL wall StripTool traces "flatlined", as happens when we had the EPICS freezes in the past - except that all these traces were flat for more than 3 hours. I checked that the c1psl slow machine responded to ping, and I could also telnet into it. I tried opening the StripTool on pianosa and all the traces were responsive. So I simply re-started the PSL StripTool on zita. All traces look responsive now.

  13150   Sat Jul 29 14:05:19 2017 gautamUpdateGeneralPSL StripTool flatlined

The PMC was unlocked when I came in ~10mins ago. The wall StripTool traces suggest it has been this way for > 8hours. I was unable to get the PMC to re-lock by using the PMC MEDM screen. The c1psl slow machine responded to ping, and I could also telnet into it. But despite burt-restoring c1psl, I could not get the PMC to lock. So I re-started c1psl by keying the crate, and then burt-restored the EPICS values again. This seems to have done the trick. Both the PMC and IMC are now locked.


Unrelated to this work: It looks like some/all of the FE models were re-started. The x3 gain on the coil outputs of the 2 ITMs and BS, which I had manually engaged when I re-aligned the IFO on Monday, were off, and in general, the IMC and IFO alignment seem much worse now than it was yesterday. I will do the re-alignment later as I'm not planning to use the IFO today.

  13151   Sat Jul 29 16:24:55 2017 jamieUpdateGeneralPSL StripTool flatlined
Quote:
Unrelated to this work: It looks like some/all of the FE models were re-started. The x3 gain on the coil outputs of the 2 ITMs and BS, which I had manually engaged when I re-aligned the IFO on Monday, were off, and in general, the IMC and IFO alignment seem much worse now than it was yesterday. I will do the re-alignment later as I'm not planning to use the IFO today.

This was me.  I restarted the front ends when I was getting the MX streams working yesterday.  I'll try to me more conscientious about logging front end restarts.

  16056   Wed Apr 21 00:08:15 2021 KojiUpdatePSLPSL Table (sort of) covered / HEPA "chimney"

Shutdown Procedure:
PSL Shutter closed / MC Autolocker disabled / PSL mechanical shutter closed / Laser injection current turned to zero / Laser turn off (red button) / Laser key turned off

The laser stat before the shutdown:
- LD Temp A: Set 22.07 (Untouched)
- LD Temp B: Set 21.03(Untouched)
- Laser Injection Current: Dial 9.53, Actual 2.100 -> Dial was moved to zero upon shutting down
- Laser Crystal Temp: Dial 3.34 (untouched)  Set 30.57 Actual 30.60 (Untouched)

PSL Table covering

- Because of the so many cables going up and down, sealing the PSL table with the metalized sheet was not easy. Therefore, the sheets have been just softly laid above the optics. (Attachment 1)
- The largest sheet which covers the east half of the table was taped to the table at the bottom, so that the air from the chimneys (see below) does not come up to the table

- The large dust could come from the opening of the enclosure during the filter replacement. So it was considered to be easier to seal the openings. (Attachment 2)
- Of course, the HEPAs are going to be tested after the maintenance work. It means that vent paths were needed so that the seals do not explode with the pressure (together with dust).
- Thus, the tubes of the sheets are attached to the seals to form "chimneys" for guiding the airflow beneath the table. (Attachment 2/3/4)
- This configuration was not meant to be sufficiently strong for a continuous run of the fans. Long running of the HEPAs may cause the failure of the seal tapes.
  Therefore the HEPA test should be done with a low flow rate and/or a short period of high flow.

- Once the work has been done, all the sheets should be carefully removed without scattering the fallouts onto the optics.

 

Attachment 1: 20210420235324_IMG_0560.jpeg
20210420235324_IMG_0560.jpeg
Attachment 2: 20210420235304_IMG_0559.jpeg
20210420235304_IMG_0559.jpeg
Attachment 3: 20210420235243_IMG_0558.jpeg
20210420235243_IMG_0558.jpeg
Attachment 4: 20210420235344_IMG_0562.jpeg
20210420235344_IMG_0562.jpeg
  16057   Wed Apr 21 01:14:03 2021 KojiUpdatePSLPSL Table (sort of) covered / HEPA "chimney"

I also located the (possible) HEPA filters in the lab. (Attachments 1~3)

Oh! This is NO-NO! We can't place anything in front of the mains breakers. (Attachment 2)
I relocated the objects (Attachment 3)

 

Attachment 1: P_20210421_005056.jpg
P_20210421_005056.jpg
Attachment 2: P_20210421_005114.jpg
P_20210421_005114.jpg
Attachment 3: P_20210421_005302.jpg
P_20210421_005302.jpg
  2127   Wed Oct 21 11:41:29 2009 ZachUpdateWIKI-40M UpdatePSL Table Diagram wiki entry

 I made a wiki entry for the PSL table diagram under the PSL directory on the 40mHomePage. I tried to use the ImageLink macro to use a resized (smaller) version of the diagram as a link to the full image, which it is designed to do if there is no target given, but it didn't seem to work. Instead, I had to create a second page that had the full-sized diagram, and I used ImageLink with a smaller version to link to that page.

The inventory that is shown is clearly incomplete. Part of this is due to the fact that many labels were either missing or impossible to read without touching stuff. For those components with labels missing, I tried to infer what they were to the best of my knowledge, but I wasn't able to for all of them. In true wiki spirit, everyone is encouraged to fill in any additional information they might have on these components. 

  2128   Wed Oct 21 13:07:54 2009 KojiUpdateWIKI-40M UpdatePSL Table Diagram wiki entry

http://lhocds.ligo-wa.caltech.edu:8000/40m/PSL_Table_Diagram

Thanks. I love this. Could you also put the original file that is editable for future modification by anyone?

Quote:

 I made a wiki entry for the PSL table diagram under the PSL directory on the 40mHomePage. I tried to use the ImageLink macro to use a resized (smaller) version of the diagram as a link to the full image, which it is designed to do if there is no target given, but it didn't seem to work. Instead, I had to create a second page that had the full-sized diagram, and I used ImageLink with a smaller version to link to that page.

The inventory that is shown is clearly incomplete. Part of this is due to the fact that many labels were either missing or impossible to read without touching stuff. For those components with labels missing, I tried to infer what they were to the best of my knowledge, but I wasn't able to for all of them. In true wiki spirit, everyone is encouraged to fill in any additional information they might have on these components. 

 

  2134   Thu Oct 22 15:49:29 2009 ZachUpdateWIKI-40M UpdatePSL Table Diagram wiki entry

Quote:

http://lhocds.ligo-wa.caltech.edu:8000/40m/PSL_Table_Diagram

Thanks. I love this. Could you also put the original file that is editable for future modification by anyone?

Quote:

 I made a wiki entry for the PSL table diagram under the PSL directory on the 40mHomePage. I tried to use the ImageLink macro to use a resized (smaller) version of the diagram as a link to the full image, which it is designed to do if there is no target given, but it didn't seem to work. Instead, I had to create a second page that had the full-sized diagram, and I used ImageLink with a smaller version to link to that page.

The inventory that is shown is clearly incomplete. Part of this is due to the fact that many labels were either missing or impossible to read without touching stuff. For those components with labels missing, I tried to infer what they were to the best of my knowledge, but I wasn't able to for all of them. In true wiki spirit, everyone is encouraged to fill in any additional information they might have on these components. 

 

 Do you mean the diagram or the inventory? The diagrams are online as attachments (small versions on the main "PSL Table Diagram" page and large versions on the linked pages). The inventory is easily editable on the wiki itself. It's just rendered in table form using the CSV parse utility for "comma-separeted values" (though you actually need to use semicolons, for reasons unknown).

  2135   Thu Oct 22 21:58:26 2009 KojiUpdateWIKI-40M UpdatePSL Table Diagram wiki entry

Diagram. I don't want to say PNG is an editable format for this purpose...
You have the PPT, PDF or any drawing format to create this diagram.

Quote:

http://lhocds.ligo-wa.caltech.edu:8000/40m/PSL_Table_Diagram

Thanks. I love this. Could you also put the original file that is editable for future modification by anyone?

 Do you mean the diagram or the inventory? The diagrams are online as attachments (small versions on the main "PSL Table Diagram" page and large versions on the linked pages). The inventory is easily editable on the wiki itself. It's just rendered in table form using the CSV parse utility for "comma-separeted values" (though you actually need to use semicolons, for reasons unknown).

 

  2136   Thu Oct 22 23:14:54 2009 ZachUpdateWIKI-40M UpdatePSL Table Diagram wiki entry

Quote:

Diagram. I don't want to say PNG is an editable format for this purpose...
You have the PPT, PDF or any drawing format to create this diagram.

Quote:

http://lhocds.ligo-wa.caltech.edu:8000/40m/PSL_Table_Diagram

Thanks. I love this. Could you also put the original file that is editable for future modification by anyone?

 Do you mean the diagram or the inventory? The diagrams are online as attachments (small versions on the main "PSL Table Diagram" page and large versions on the linked pages). The inventory is easily editable on the wiki itself. It's just rendered in table form using the CSV parse utility for "comma-separeted values" (though you actually need to use semicolons, for reasons unknown).

 

 

Good news and bad news. For the MOPA diagram, which I did recently, I have GIMP file with separate layers for the background image, ray traces, and labels. Unfortunately, I didn't realize that this was the best way to do it until I had done most of the ray tracing for the main diagram, so, although I have that file in GIMP as well, only the labels are on a separate layer. If this is a major issue I can do the tracing again. The other thing is that the original files are quite large: 17.3 MB for the MOPA, and 64.1(!) MB for the main diagram. Let me know what you think.

  3391   Tue Aug 10 05:56:07 2010 KojiUpdatePSLPSL Table Lifting Preparation

Work on Aug 9th

Steve, Jenne, Koji, Alberto, Aidan, Jan, Sharmila, Katherine

From 9am to 6pm

  • Shutting down the PSL after the 90885 hours of service
  • Removals
    • The accelerometers
    • The reference cavity chamber
    • The periscopes were left so far
  • The cables between the PSL table and the outside have been disconnected
    • Listed items on Friday
    • Some unlisted items recorded and disconnected
    • Drained the cooling water from the chiller lines
    • Pulled out the chiller connections at the control room as well as the chiller control cables (temp sens & RS232C)
  • Sealed the PSL table with plastic sheets
    • Put antistatic films to the table (they are supported by the long optical poles)
    • Used capton tapes to fix the films on to the table
    • Put the white huge plastic sheet to cover the table at once
    • Some spaces at the edge of the tables are left flat such that the C-clamps can be attached
  • Sealed the AP and the ITMY tables by capton tapes

Some photos are attached in this entry. All of the photos found in the picasa album (click the slideshow)

Attachment 1: IMG_2686.jpg
IMG_2686.jpg
Attachment 2: IMG_2691.jpg
IMG_2691.jpg
Attachment 3: IMG_2692.jpg
IMG_2692.jpg
Attachment 4: IMG_2711.jpg
IMG_2711.jpg
  10371   Tue Aug 12 23:07:24 2014 HarryUpdateGeneralPSL Telescope

I put the PSL telescope in place, and started coupling to it.

Unfortunately, I was only able to couple about 55 uW into the "fiber coupler" (read: fiber coupled splitter). See picture below:

PSLTelescopePic.png

Additionally, I'm not sure why this is, but both of the splitters we ordered don't split equally, but to 90% and 10% in each output port.

We also found that, since we aren't using the fibers we originally intended to, the specs are a little different, and the waist we're trying to have at the collimator face is now 283 um.

  3463   Tue Aug 24 12:03:57 2010 ranaUpdatePSLPSL Upgrade: Mode Matching from PMC to IMC

I used the free software called 'ABCD' for Mac to construct this mode matching solution for going from the PMC to the IMC.

After getting it close by eye, I plugged the initial guess into Matlab and let it optimize the distances. I then plugged this into 'ABCD'

to get the exact solution. ABCD doesn't actually optimize anything; it just makes a nice table and graphically plots the solution.

  • The first waist between the first lens (f = +200 mm) and the second lens (f = -150 mm) is where the triple mod EOM goes. I have not accounted for the index (1.75) of the KTP.
  • The third lens we need is a f = +400 mm lens. I have put the lenses in the new layout drawing at the positions indicated in the Omnigraffle drawing. Each grid square corresponds to 1 inch.

The part numbers for these lenses are:

PLCX-25.4-103.0-UV-1064
PLCC-25.4-77.3-UV-1064
PLCX-25.4-206.0-UV-1064
40mPSL.pngScreen_shot_2010-08-24_at_6.07.43_PM.png
  3469   Wed Aug 25 15:32:52 2010 ranaUpdatePSLPSL Upgrade: Mode Matching from PMC to IMC

In a manner similar to the now classic 'Mode Matching from PMC to IMC' entry, I have calculated the lenses and positions needed to match the 2W NPRO beam into the PMC.

The added complication is that we also want to have a reasonable beam size to get into the Faraday and the AOM. It seems that this should be possible using one lens.

After the beam comes out of the AOM, there's another lens to match to the PMC. Its possible to do this with more lenses, but this is just an effort to minimize the number

of surfaces in the beam.

40mPSL.pngScreen_shot_2010-08-25_at_6.26.23_PM.png

 

  3470   Wed Aug 25 15:42:01 2010 JenneUpdatePSLPSL Upgrade: Mode Matching from PMC to IMC

Thoughts on where to take the pickoff for the SHG for the PSL-green?  We discussed today at the meeting the possibility of putting a 90/10 beam splitter right after the PMC, so that the green team would get somewhere between 100-200mW. 

Quote:

40mPSL.png

 

 

  13590   Wed Jan 31 15:29:44 2018 johannesUpdateDAQPSL acromag server moved from megatron to c1auxex2

I moved the epics IOC server process for the single Acromag ADC that monitors the PSL signals from megatron to c1auxex2.

First, I disabled the legacy support on all channels as explained in elog 13565. Then I copied the files npro_config.cmd and NPRO.db from /opt/rtcds/caltech/c1/scripts/Acromag to /cvs/cds/caltech/target/c1psl2/ following the pattern of the old Motorola machines and the new c1auxex2. I had to make some edits for correct paths and expanded the epics records to the standard we're using for ETMX.

I then added a service to systemd on c1auxex2 that runs the epics IOC for the Acromag PSL channels: /etc/systemd/system/modbusPSL.service. No more tmux on megatron.

Running two IOCs on a signle machine at the same time did not produce any errors and seems fine so far.

  10287   Tue Jul 29 18:52:42 2014 HarryUpdateGeneralPSL and AUX Coupling Waist Measurement

//edit Manasa//  Harry will update this elog with before/after pictures of the table and power of the 1064nm rejected beam from the SHG.
While making these measurements, I reduced the Y end laser power (decreasing the current) so that we could use the beam profiler without burning anything and then brought it back up to the nominal power after the measurements were done.

Purpose

We wanted to take measurements of "waists" of the PSL and AUX (Y-Arm) so I can then design a telescope to couple both into fibers for use in FOL.

Measurements

For both lasers, PSL and AUX, I measured the profile of the dumped red (1064nm) beams coming out of the second harmonic generators, as this is the light that we will be using in FOL.

The power in the beam I measured from the PSL was 87.5 mW, and the power in the measured beam at the end table was 96 mW (when reduced from nominal power).

I used the beam profiler to take measurements of spot size at multiple points along the optical axis of both lasers.

An issue with these measurements was space constraints. In other words, there was no room on either table for a translation stage to hold the Profiler. I used a tape measure to determine Z-Coordinates. However, especially in the case of the AUX laser, parallax error caused uncertainty in my position measurements, which I would estimate at plus and minus 1.5cm.

I then fit these data using ALM to determine waist size and location for use in telescope design.

Z = 0 in the PSL graph is the face of the first mirror in the beam path, and in the AUX graph Z = 0 is the face of the SHG.

NPROProfileMeasurement.png

PSLProfile.pngAUXProfile.png

My measurement of the PSL gave:

X Waist = 43um at z = 6.8mm, as measured from the face of the SHG.

Y Waist = 44um at z = 6.8mm, as measured from the face of the SHG.

AUX Measurements gave:

X Waist = 44um at z = -3.1mm from the SHG face

Y Waist = 36um at z = -3.6mm from the SHG face

 

Find attached alm files in .zip

Movement on the Tables

In order to facilitate the measurements, we needed to move some things around, as pictured below.

On the PSL table, we installed a steering mirror after the Green filtering mirror, which is immediately after the SHG output, in addition to appropriate beam dumps.

before PSLBefore.png      after   PSLAfter.JPG

At the end table, we removed some unused optics, as well as a PD, which were in the way . //edit// manasa: We removed IPANG (which has no light on it) and the associated steering optics.

before    AUXBefore.JPG  after   AUXAfter.JPG

Moving Forward

Either tonight or tomorrow morning, I will use these data to design coupling telescopes for the PSL and AUX light.

Tomorrow, I will couple both lasers to fibers, and hopefully finish assembling the optics for FOL

Attachment 4: FOL.zip
Attachment 8: AUXBefore.JPG
AUXBefore.JPG
  11940   Wed Jan 20 23:26:10 2016 gautam, ranaUpdateLSCPSL and AUX-X temperatures changed

Earlier today, we did a bunch of stuff to see if we could improve the situation with the excess ALS-X noise. Long story short, here are the parameters that were changed, and their initial and final values:

X-end laser diode temperature:     28.5 degrees ---> 31.3 degrees

X-end laser diode current:             1.900 A ---> 1.942 A

X-end laser crystal temperature:   47.43 degrees ---> 42.6 degrees

PSL crystal temperature:              33.43 degrees ---> 29.41 degrees

PSL Diode A temperature:           21.52 degrees ---> 20.75 degrees

PSL Diode B temperature:           22.04 degrees ---> 21.3 degrees 

The Y-end laser temperature has not yet been adjusted - this will have to be done to find the Y-beatnote.

Unfortunately, this does not seem to have fixed the problem - I was able to find the beatnote, with amplitude on the network analyzer in the control room consistent with what we've been seeing over the last few days, but as is clear from Attachment 1, the problem persists...

 


Details:

  • PSL shutter was closed and FSS servo input was turned off. 
  • As I had mentioned in this elog, the beat can now only be found at 47.41 degress +/- 1 deg, which is a shift of almost 5 degrees from the value set sometime last year, ~42.6 degrees. Rana thought it's not a good idea to keep operating the laser at such a high crystal temperature, so we decided to lower the X-end laser temperature back to 42.6 degrees, and then adjust the PSL temperature appropriately such that we found a beat. The diode temperature was also tweaked (this requires using a small screwdriver to twist the little knob inset to the front panel of the laser controller) - for the end laser, we did not have a dedicated power monitor to optimize the diode temperature by maximizing the current, and so we were just doing this by looking at the beat note amplitude on the network analyzer (which wasn't changing by much). So after playing around a little, Rana decided to leave it at 31.3 degrees.
  • We then went to the PSL table and swept through the temperature till a beat was found. The PMC wouldn't stay locked throughout the sweep, so we first did a coarse scan, and saw weak (due to the PMC being locked to some weird mode) beatnotes at some temperatures. We then went back to 29.41 degrees, and ran the PMC autolocker script to lock the PMC - a nice large beatnote was found. 
  • Finally, Rana tweaked the temperatures of the two diodes on the PSL laser controller - here, the optimization was done more systematically, by looking at the PMC transmitted power on the oscilloscope (and also the MEDM screen) as a function of the diode temperature.
  • I took a quick look at the ALS out of loop noise - and unfortunately, our efforts today does not seem to have noticeably improved anything (although the bump at ~1kHz is no longer there). 

Some details not directly related to this work:​ 

  • There are long cables (routed via cable tray) suitable for RF signals that are running from the vertex to either end-table - these are labelled. We slightly re-routed the one running to the X-end, sending it to the IOO rack via the overhead cable tray so that we could send the beat signal from the frequency counter module to the X-end, where we could look at it using an analyzer while also twiddling laser parameters.
  • A webcam (that also claims to have two-way audio!) has been (re?)installed on the PSL table. The ethernet connection to the webcam currently goes to the network switch on the IOO rack (though it is unlabelled at the moment)
  • The X-end area is due for a clean-up, I will try and do some of this tomorrow. 
Attachment 1: 2016_01_20_ALS_OutOfLoop_1.pdf
2016_01_20_ALS_OutOfLoop_1.pdf
  11942   Thu Jan 21 18:34:04 2016 ranaUpdateLSCPSL and AUX-X temperatures changed

Is the black ref spectrum from this year or from May of 2015 or ?

I wonder if the noise is a bunch of fast spikes or if its a true broadband rumble. Maybe we can tell by looking at the analog DFD or PLL outputs?

  10671   Wed Nov 5 17:50:29 2014 manasaUpdateGeneralPSL and AUXY beatnote in IR found

Found the IR beatnote between PSL and Y end laser.

Since our goal was to find the beatnote ASAP to recover ALS, I ignored the fine details in alignment. I will revisit the setup to make some improvements in the near future.

1. Coupled the PSL IR beam leaking after the doubler into the fiber. We have only 10% coupling into the fiber at the PSL table right now (6mw); but this will be improved once I get a suitable translation stage for the telescope.

2. PSL IR --> PM980 fiber --->50-50 fiber beam splitter ---> 50-50 fiber beam combiner
  AUX Y ---> PM980 fiber ---> 50-50 fiber beam combiner

The output port of the fiber beam combiner is connected to the fiber coupled broadband RF PD.

3. The RF output of the PD when connected to a spectrum analyzer shows a beatnote of -50dBm. The small amplitude of the beatnote is due to the laser power being attenuated before coupling into the fiber to keep the PD safe.

Attached is photo of how the setup is put on the PSL table. We will put all the stuff in a box once the X setup is also in place.

Attachment 1: PSLsetup.jpg
PSLsetup.jpg
  10672   Wed Nov 5 18:08:00 2014 ericqUpdateLSCPSL and AUXY beatnote in IR found

Green beatnotes recovered.

It was just a matter of aligning the arm greens and PSL greens on the PSL table. I suppose something knocked the PSL alignment out of whack... I was also able to simultaneously see the green beatnote and IR beatnote respond to Yend laser temperature. 

Locked arms on POX/POY, checked RMS of ALS-BEAT[X/Y]_FINE_PHASE_OUT_HZ channels. 

  • ALSY: 300Hz RMS
  • ALSX: 700Hz RMS

These seem fine. Locked CARM and DARM on ALS, found IR resonances. 

ALS is back in business 

  4629   Wed May 4 15:56:09 2011 valeraSummaryGeneralPSL and MC trends

The attached plot shows 2 day trends of the PMC and MC reflected and transmitted power, the PSL POS/ANG QPD signals, and the temperature measured by the dust counter.

The power step in the middle of the plot corresponds to Koji/Jenne PMC realignment yesterday.

It looks like everything is following the day/night temperature changes.

Attachment 1: pslmcdrift.pdf
pslmcdrift.pdf
  4663   Mon May 9 09:37:51 2011 valeraUpdatePSLPSL and MC trends

The attached plot shows 7 day trends of the MC and PMC power levels, PSL QPDs, and temperature. The MC stayed locked for ~40 hours over the weekend. The temperature swings were somewhat smaller over the past couple of days but one should remember to turn the PSL HEPA down after working on the table. Steve turned the HEPA flow from 100% down to 20% on Thursday and posted the reminder signs on the PSL enclosure.

Attachment 1: pslmcdrift2.pdf
pslmcdrift2.pdf
  6724   Thu May 31 01:27:16 2012 yutaUpdateGreen LockingPSL and Y arm green beams aligned

[Jenne, Yuta]

We aligned the PSL green optics so that the PSL green beam and Y arm green beam interfere. 2 beams are now hitting the Y arm beat PD. The DC level from the beat PD is about 13 mV.

We didn't try to see the beat signal for today, because the temperature of the doubling crystal seemed funny. We need to look into it tommorow.

Currently, the temperature control is enabled and the set point is 36.9 deg C, but the temperature is stuck at 33.0 deg C.

  1326   Thu Feb 19 22:40:33 2009 KiwamuUpdateElectronicsPSL angle QPD

I checked a broken QPD, which was placed for PSL angle monitor, and finally I cocluded one segment of the quadrant diode was broken.

The broken segment has a offset voltage of -0.7V after 1st I-V amplifier. It means the diode segment has a current offset without any injection of light.

Tomorrow I will check a new QPD for replacement.

Kiwamu IZUMI

 

  1389   Wed Mar 11 21:03:51 2009 Kakeru and KiwamuUpdateIOOPSL angle QPD

Kakeru and Kiwamu

We placed a QPD on the PSL bench for PSL angle monitor.

 

Quote:

I checked a broken QPD, which was placed for PSL angle monitor, and finally I cocluded one segment of the quadrant diode was broken.

The broken segment has a offset voltage of -0.7V after 1st I-V amplifier. It means the diode segment has a current offset without any injection of light.

Tomorrow I will check a new QPD for replacement.

Kiwamu IZUMI

 

 As we mentioned before, old QPD which used to be placed is broken.

 And we put broken QPD into the "photodiodes" box under the soldering table.

 

 

  12493   Wed Sep 14 19:41:23 2016 JohannesUpdateGeneralPSL back to high power

Today's summary:

  • Replaced mirror in MC REFL path with R=10% BS and aligned beam on PD while still at low power
  • Replaced HR mirror in Transmon path at EY table with 50/50 BS. Alignment onto QPD not yet confirmed because we need IR from the YARM for it.
  • Put ND filters back on Transmon QPDs at both X and Y ends. For now I put all the filters on, for a combined OD of 1.6 at both ends (1.0 + 0.6 at YEND and 1.0 + 0.4 + 0.2 at XEND).
  • Put ND filter back on Transmon CCD on EY table.
  • Reverted MC autolocker to nominal, high power version.
  • Raised PSL output power back to nominal level by turning the waveplate. At the PSL shutter I measured a power of 1.03W. It occured to me too late that I realigned the PMC only afterwards and increased its transmission by a few percent, so I'll have to re-measure the actual PSL power.
  • MC is locked with its transmission back up to ~15,400 counts. The autolocker is not very good at obtaining the lock, as it seems to try to turn the VCO gain up too far and loses lock. The script probably needs a revision.
  • The YARM was pretty badly aligned. We used the green light to visually center the beam on the test masses AND had to go exploring with the TTs to see IR flashes in the first place. We got the YARM to lock to IR and were able to run the dither alignment. The maximum transmission we saw was on the order of 0.85. However, something strange is happening with the LSC control of the armlength. When the lock is engaged it drives PIT and YAW, which manifests itself in the OpLev signal and variable transmitted power on the TRY PDs. Osamu helped us diagnose this and was able to reduce the effect by tuning the POS gains to the individual ETMY OSEMS. The problem persisted even after using the new matrix diagonalization coefficients, we'll have to investigate this further and also take a look at the filters in the feedback path.
  • ITMX is still stuck and way out of alignment, so we couldn't even start with the green light in the XARM.
  1725   Wed Jul 8 19:13:19 2009 AlbertoUpdatePSLPSL beam aligned to the Mode Cleaner

Today I tuned the periscope on the PSL table to align the beam to the Mode Cleaner. With the Wave Front Sensor control off, I minimized the reflection from the MC and maximized the transmission. While doing that I also checked that the transmitted beam after the MC didn't lose the alignment with the interferometer's main Faraday isolator.

In this way, I've got a reflection, as read from the MC_REFLPD_MC, of about 0.6. Then I centered the WFS on the AS table. After that the WFS alignment control brought the reflection to 0.25 and a nice centered bull-eye spot showed on the monitor.

  3511   Thu Sep 2 01:44:13 2010 JenneUpdatePSLPSL beam hitting the PMC!

[Rana, Jenne]

More PSL progress. 

The new laser was raised to a 4 inch beam height using basically the most randomly thrown together method possible.  (It'll work just fine for aligning things, but we seriously need to get a nice block made.)  The PMC and the nice Osamu-mirror mount to go into the PMC also have temporary risers, so we'll need to replace them with the real deal as soon as we get things back from the shop.

So far we've got (1) the lens after the laser, (2) a Half Wave Plate (no quarter wave plate yet), (3) steering mirror that will go after the EOM, (4) 2 steering mirrors to get into the PMC, in addition to all of the stuff that we did the other day.  With all of this stuff we've got the beam hitting the 1st PMC mirror. We still don't have the EOM and AOM in the beam path however.

To get the rough alignment that we did, we turned on the new 2W NPRO, operating at the minimum power we could see on a card.  We turned it off after use, so it is still off.  Steve, we left the cable for the interlock sitting on the PSL table on the NW corner....can you please hook it up tomorrow?  Also, after the interlock is installed we should go back to regular running laser hazard mode. 

 

 

  3519   Fri Sep 3 06:55:42 2010 ranaUpdatePSLPSL beam hitting the PMC!

NPRO

Koji and I inspected and photographed the laser after opening up its case. I then drilled the clearance holes in the 4 corners and tapped holes for 1/4-20. I was careful to tap with the laser sideways, to avoid shavings getting into the laser and suctioned out as much of the pieces as I could. The laser is now mounted on some bad 1/4-20 based NewFocus style pedestals. The riser block can now be made with 1/4-20 through holes and the laser will sit on its for corner feet. We'll make the base aluminum to avoid differential CTE based stress in the laser base.

We checked the level of the laser. With the new mounting the beam is level to within ~1 mrad and has a 4" beam height.

 

Faraday

I've mounted the Faraday Rotator from the old MOPA. It has 8-32 mounting holes (who's shafts are curiously not parallel). We need an aluminum block of the proper height (2 3/4" ??) to make a permanent solution.

I've also mounted the thin-film polarizer. This works well, but it also needs a block machined to get the mounting to be less Mickey Mouse.

 

Pockel Cell for phase correction and 35.5 MHz PMC modulation

The EOM is mounted as before on the angle bracket to align it for P-pol light. The beam now goes cleanly through there. No further mounting hardware required.

 

Lenses

The 2 lenses in the 'mode matching telescope' between the laser and the PMC are in place, but not placed with any accuracy.

 

By sheer luck, I saw the PMC flashing in the TEM27 mode without any alignment from me. Next step is to get the lens positions tuned and then do the beam scan on the beam going towards the PMC to verify the approximate mode matching. This is all crude, but I just want to get the beam going into the vacuum as fast as possible.

  5013   Thu Jul 21 16:05:15 2011 sureshUpdateIOOPSL beam into MC realigned

 I realigned the PSL beam going into the MC.

The MC beam was realigned so as to maximise the power in the MC.  I minimised the MC_RFPD_DCMON dial on the MC_ALIGN screen while adjusting the two zig-zag mirrors at the end of the PSL table.

  5505   Wed Sep 21 19:20:41 2011 SureshUpdateIOOPSL beam into MC was off in Pitch. Readjusted.

I found the PSL beam into the MC off in pitch by large amount.  I readusted the PSL beam for optimal coupling.

The beam had shifted on the WFS as well.  So I recentered the DC signal on the WFS with the MC unlocked.  However both the DC and RF signals on the WFS shift when we lock the MC.  This ought to indicate sub-optimal coupling of PSL into MC.  But instead, if we were to reduce these offsets on the WFS by adjusting the MC axis it leads to higher reflected power from the MC.

The current plan is to retain these RF offsets and lock the WFS with a DC offset in the servo filters.

  6113   Tue Dec 13 16:31:40 2011 ZachUpdateIOOPSL beam realigned into MC

The MC coupling had become re-shittified. As we need transmitted MC light for the RAMmon, I realigned the input beam to the MC. (Jenne said that the MC mode itself should be well aligned, so I just used the zigzag on the PSL). MC_REFL is now ~0.5-0.6.

  6114   Tue Dec 13 18:56:23 2011 ranaUpdateIOOPSL beam realigned into MC

 

 Of course, looking at the MC transmission os the important thing, but I wonder if maybe we should also monitor the beam before it goes into the MC just to see if its the fault of the MC-WFS or not. In the bad old MZ days, I remember that the MC mirror alignment would drastically change the post-MC RAM.

It requires another PD/demod set, but may be illuminating in the end. 

Also, can someone please add some channels to EPICS which calibrate the RAM channels into RAM units?

  5533   Fri Sep 23 18:00:54 2011 SureshUpdateIOOPSL beam realigned to MC

I noticed that the beam centering on the WFS had changed over night and the MC_TRANS_SUM was about 40k counts.  When well aligned this SUM is around 50-55k counts. So PSL coupling into MC was suboptimal. It was not clear whether the MC shifted or the PSL beam shifted. So I looked at the PSL ANG and POS QPDs. 

 trend.png

The plots above show the gradual drift of the PSL beam in vertical direction during the last 8hrs or so. But the last bit shows the adjustments I had to make to reobtain optimal alignment.  And these adjustments are not undoing the drift!  This would indicate that the MC axis has also shifted during the same time period. 

  3703   Wed Oct 13 00:35:26 2010 kiwamuUpdateGreen LockingPSL beat note setup

[ Kevin and Kiwamu ]

 We made the setup for the green PLL stuff on the PSL table.

 Now the two green beams are happily going to the RFPD.

Tomorrow we try to catch the beat note signal 

 

  - - - what we did

 * took the two light doors out from the OMC and the MC chamber in order to let the green light go through there.

 * using aluminum foils we covered the space between the OMC and the MC chamber in order to protect from dust

 * aligned the steering mirrors inside of the chamber because the height of the green light coming out from the chamber had been a little bit low at the PSL table.

 * at the PSL table we put several steering mirrors and a beam splitter which combines the two green lights

 * installed Hartmut's RFPD and applied -150V bias on it.

 * put a lens on each path of the green beam in order to make the beam size approximately the same at the RFPD

 * closed the light doors

 

- - - Notes

 * At the beginning, an output signal from the RFPD was pretty small ( less than 1mV at DC ), so I replaced a feedback resistor that was 241 Ohm by 24 kOhm.

   As a result the signal became about 10mV when the green lights go into the PD.

* Actually the power of the green beams are so weak.

  I measured them by using a Newport power meter, it said something like 4 uW for both of the green lights. 

  One of the reasons is that the transmitted light from the PMC which generates one of the green lights is already weak. It's about 480 mW ( while more than 600 mW was reflected by the PMC ! ).

  I am going to make sure if these numbers are reasonable or not.

 

  3727   Fri Oct 15 06:31:52 2010 kiwamuUpdateGreen LockingPSL beat note setup: part II

 I made some KAIZENs (what does kaizen mean ? ) for the PSL green setup.

I replaced the lenses for the modematching of the two green lights at the PSL table, and the beams now look pretty identical.

Also I tuned the temperature setpoint of the doubling crystal and eventually the green light increased to 14 uW at the PSL table.

Once I finish the modification of the RFPD tomorrow, I am going to search for the beat note signal.

 


( details )

 - In-vac green mirrors

   I found one of the green steering mirror, which stands at the corner of the MC table, was clipping the green light.

  So I steered another mirror, which sends the beam to the clipping mirror after the downward periscope.

 I touched also the last steering mirror in the OMC chamber to correct the alignment.

 

 - temperature of the doubling crystal

   I took a quick temperature scan in order to find an optimum point for the crystal temperature.

  The scan was performed by just turning the heater off after I heated up the crystal up to 40 deg. 

  Using the NewPort power meter I found the optimum point around 37.3 deg. So I set the temperature to that point.

 

 - mode matching lenses

 As written in this entry , Kevin and I had put some lenses to make the two green beam almost the same size at the RFPD.

 But today while I was checking these mode-profiles by using a sensor card, I found they were not so matched.

 Therefore I replaced these lenses to match them more.

The idea of this replacement is t to let them have a long Rayleigh range, such that they can efficiently and easily interfere because of the flatness of their wave fronts along a distant.

 For the green light from the chamber, I put one more lens to form a Keplerian beam shrinker (see here about the Keplerian lens configuration).

 They look pretty identical now.

 

  7006   Mon Jul 23 18:38:58 2012 JenneUpdatePSLPSL channels added to IOO model

I added a subblock to the IOO model, and gave it a top_names of PSL, so the channels show up as C1:PSL-......

So far, there are just 2 channels acquired, C1:PSL-FSS_MIXER and C1:PSL-FSS_FAST, since those were already connected to the ADC.  Those signals are both on the DAQ OUT of the FSS board in the rack.  They are DQ channels now too.

 

  7010   Mon Jul 23 19:13:12 2012 JenneUpdatePSLPSL channels added to IOO model

Quote:

I added a subblock to the IOO model, and gave it a top_names of PSL, so the channels show up as C1:PSL-......

So far, there are just 2 channels acquired, C1:PSL-FSS_MIXER and C1:PSL-FSS_FAST, since those were already connected to the ADC.  Those signals are both on the DAQ OUT of the FSS board in the rack.  They are DQ channels now too. 

 So there was a problem with the channel name C1:PSL-FSS_FAST, which conflicts with an existing slow channel.  This was causing daqd to fail to start (shockingly, with an appropriate error message!).  I renamed the channel to be C1:PSL-FSS_NPRO until we come up with something better.

After the change everthing worked and fb came back.

ELOG V3.1.3-