40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log, Page 184 of 339  Not logged in ELOG logo
ID Date Author Type Category Subjectup
  3579   Wed Sep 15 19:29:13 2010 valeraSummary PSL power budget
 Location  Power (mW)
 NPRO - after HWP  252
 Rejected by input FI polarizer  38
 After output FI polarizer  175
 Into PMC  164
 PMC reflected  37
 PMC transmitted  71
 PMC leakage  1.5
 After PMC TRANS PD/Camera BS

 1.2

 After RefCav EOM  1.1
 Into RefCav  0.3

 Notes:

- NPRO injection current 1.0 A

- PMC losses ~32%

- FSS AOM diffraction efficiency ~52%

  3364   Thu Aug 5 00:17:41 2010 KojiUpdatePSLPSL preparation work

We start the work on the cables at around the PSL table.

Aug 5th 10am-4pm?: (Kiwamu, Alberto, Koji)
- Removal of the unused cables around the PSL table and the control room
- Removal of the cable ties on the PSL frame

- Removal of the big nuts at the side of the PSL table

Aug 6th 10am-4pm?: (Kiwamu, Alberto, Koji, Jenne (~noon) )
- Labeling of the cables
- Planning of the disconnection

Aug 9th  9am-5pm: (Steve, Jenne, Alberto, Koji)
- Shutting down of the PSL
- Disconnection of the cables
- Draining of the cooling water
- Removal of the accelerometers
- Removal of the PSL chamber
- Sealing of the table with the plastic sheets

  3370   Thu Aug 5 22:36:11 2010 KojiUpdatePSLPSL preparation work

PSL preparation work

Aug 5th 10am-4pm?: (Kiwamu, Alberto, Koji)

  • Removing the unused cables around the PSL table and the control room

Aug 6th 10am-4pm?: (Kiwamu (ex. noon-2pm), Alberto, Koji, Jenne ('till noon) )

  • Labeling the cables to be disconnected / making the records ==> All
  • Removals
    • the big nuts at the side of the PSL table ==> Steve
    • the cable ties on the PSL frame ==> Easy
    • Innolight 2W ==> Kiwamu
    • the green pickoff optics at the edge, if necessary ==> Kiwamu talking with Steve
    • Optics on the shelf ==> Jenne / Koji
    • Oscilloscopes on the shelf ==> Jenne / Koji
    • CCD camera connections (optional, as far as not critical for the operation)
  • Put poles on the table (for the plastic sheet) ==> Alberto / Koji

Aug 9th  9am-5pm: (Steve, Jenne, Alberto, Koji)

  • Disconnecting the cables ==> All
  • Shutting down the PSL ==> Steve/Koji
    • Draining the cooling water  ==> Steve
  • Removals
    • The accelerometers ==> Jenne
    • the PSL chamber ==> Steve
    • Periscopes ==> Alberto
  • Sealing of the table with the plastic sheets

 

  • The chiller is planned to go to MIT

 

  3371   Fri Aug 6 08:09:15 2010 steveUpdatePSLPSL preparation work

Quote:

PSL preparation work

Aug 5th 10am-4pm?: (Kiwamu, Alberto, Koji)

  • Removing the unused cables around the PSL table and the control room

Aug 6th 10am-4pm?: (Kiwamu (ex. noon-2pm), Alberto, Koji, Jenne ('till noon) )

  • Labeling the cables to be disconnected / making the records ==> All
  • Removals
    • the big nuts at the side of the PSL table ==> Steve
    • the cable ties on the PSL frame ==> Easy
    • Innolight 2W ==> Kiwamu
    • the green pickoff optics at the edge, if necessary ==> Kiwamu talking with Steve
    • Optics on the shelf ==> Jenne / Koji
    • Oscilloscopes on the shelf ==> Jenne / Koji
    • CCD camera connections (optional, as far as not critical for the operation)
  • Put poles on the table (for the plastic sheet) ==> Alberto / Koji

Aug 9th  9am-5pm: (Steve, Jenne, Alberto, Koji)

  • Disconnecting the cables ==> All
  • Shutting down the PSL ==> Steve/Koji
    • Draining the cooling water  ==> Steve
  • Removals
    • The accelerometers ==> Jenne
    • the PSL chamber ==> Steve
    • Periscopes ==> Alberto
  • Sealing of the table with the plastic sheets

 

  • The chiller is planned to go to MIT

 

Monday, August 9

 We should move the reference cavity too. Will this cavity be pumped while relocated?

Check and insure that attached and cut-free cables of PSL have enough room to tolerate the raising of the enclosure by 6"

I had second thoughts about the power line to the OMC. Koji was right, we should disconnect them from the power supplies.

The PSL enclosure doors on the north side will have to be removed some times to move exiting and entering ports.

 

  3381   Fri Aug 6 20:00:03 2010 KojiUpdatePSLPSL preparation work

PSL preparation work report

Aug 6th 10am-5pm: (Steve, Jenne, Alberto, Kiwamu, Koji)

- We labeled the cables to be disconnected

  • These will be disconnected in order to isolate the PSL table and the frame (housing) from the other part of the lab.
  • Upon the labeling we made the list and the map of the cables to be removed.
  • On Monday we disconnect those cables one by one accoding to the list.

- The following stuffs have been removed from the PSL table

  • The big nuts at the side of the PSL table
  • The cable ties on the PSL frame
  • Innolight 2W
  • The green pickoff optics at the edge
  • The optics on the shelf
  • The oscilloscopes on the shelf

- The OMC power supply cable was visited.

  • The connections to the power supply were removed. There are two HV outputs.

- We put thick and long optical poles

  • They are placed at the edge of the table so that we can put the plastic sheets on the table without touching the optics.

Plan on Monday

Aug 9th  9am-5pm: (Steve, Jenne, Alberto, Koji)

  • Disconnecting the cables ==> All
  • Shutting down the PSL ==> Steve/Koji
    • Draining the cooling water  ==> Steve
  • Removals
    • The accelerometers ==> Jenne
    • The reference cavity chamber ==> Steve
    • The small periscope ==> Alberto
  • Sealing of the table with the plastic sheets
  • The chiller is planned to go to MIT 

 

Attachment 1: PSL_cable_map.pdf
PSL_cable_map.pdf PSL_cable_map.pdf
  1950   Wed Aug 26 16:10:28 2009 Peter KingConfigurationPSLPSL reference cavity temperature box modifications

The 40m Lab reference cavity temperature box S/N BDL3002 was modified as per DCN D010238-00-C.

These were:

    R1, R2, R5, R6 was 10k now are 25.5k metal film

    R11, R14 was 10k now are 24.9k metal film

    R10, R15 was 10k now are 127k thick film - no metal film resistors available

    R22 was 2.00k now is 2.21k

    R27 was 10k now is 33.2k

    U5, the LM-336/2.5 was removed

    An LT1021-7, 7 V voltage reference was added.  Pin 2 to +15V, pin 4 to ground, pin 6 to U6 pin 3.

    Added an 8.87k metal film resistor between U6 pin 1 and U4 pin 6.

    Added an 8.87k metal film resistor between U6 pin 1 and U4 pin 15.

    The 10k resistor between J8 pin 1 and ground was already added in a previous modification.

In addition R3, R4, R7, R8, R12 and R13 were swapped out for metal film resistors of the same value

(1.00k).

    The jumper connection to the VME setpoint was removed, as per Rana's verbal instructions.

This disables the ability to set the reference cavity vacuum chamber temperature by computer.

 DSC_0731.jpg

 

 

  1953   Wed Aug 26 16:35:03 2009 AlbertoConfigurationPSLPSL reference cavity temperature box modifications

Basically, in addition to the replacement of the resistors with metal film ones, Peter replaced the chip that provides a voltage reference.

The old one provided about 2.5 V, whereas the new one gets to about 7V. Such reference voltage somehow depends on the room temperature and it is used to generate an error signal for the temperature of the reference cavity.

Peter said that the new higher reference should work better.

  4662   Sun May 8 22:59:40 2011 ranaUpdatePSLPSL reference cavity temperature box modifications

I looked at the PSL temperature box. It started out as D980400-B-C. Then it was revised by Peter King as per the LHO mods E020247.

There are some more things to do to it to make it useful for us:

  1. R3, 4, 7, 8, 12, & 13 should be changed from 1k to 0 Ohms, I think. I cannot figure out their purpose.
  2. All resistors should be made metal-film. Right now, its kind of a mish-mash.
  3. The active filter U6B has a corner frequency of ~50 Hz. This seems not useful for keeping the 4116 DAC noise out of the temperature. We should lower this to ~30 mHz to take advantage of the stability of the LT1021 which was put in.

** Frank reminds me that we don't use the TIdal or VME external inputs anymore since we moved to the EPICS/Perl PID control. So all we have to do is make sure these inputs are hardware disabled/disconnected.

  4672   Mon May 9 20:30:20 2011 ranaUpdatePSLPSL reference cavity temperature box modifications

I re-installed the box (@ ~8:15) after reflowing some of the solder joints. I will observe it over night and then remove the 1K resistors. Attached is a 8 hour minute-trend.

Attachment 1: Untitled.png
Untitled.png
  4681   Tue May 10 20:57:05 2011 ranaUpdatePSLPSL reference cavity temperature box modifications : after 24 hours still OK

Quote:

I re-installed the box (@ ~8:15) after reflowing some of the solder joints. I will observe it over night and then remove the 1K resistors. Attached is a 8 hour minute-trend.

 I compared this 24 hour trend with the one from this day exactly one year ago. Seems the same, so now I can make the resistor change.

Attachment 1: Untitled.png
Untitled.png
  1284   Mon Feb 9 16:02:42 2009 YoichiUpdatePSLPSL relative intensity noise
I attached the relative intensity noise of the PSL.
There is no bump around the lower UGF (~1Hz), but at the higher UGF (~30kHz) there is a clear bump.
When the ISS gain slider was moved up to 21dB, the peak got milder, because there is larger phase margin at higher frequencies with the current filter design.
We may want to optimize the filter later.
Attachment 1: RIN-13dB.png
RIN-13dB.png
Attachment 2: RIN-21dB.png
RIN-21dB.png
  3000   Thu May 27 10:30:32 2010 kiwamuHowToGreen LockingPSL setup for green locking

 I leave notes about a plan for the green locking especially on the PSL table.

 

 


 (1) open the door  of the MC13 tank to make the PSL beam go into the MC.  Lock it and then optimize the alignment of the MC mirror so that we can later align the incident beam from the PSL by using the MC as a reference.   

 (2) Remove a steering mirror located just after the PMC on the PSL table. Don't take its mount, just take only the optic in order not to change the alignment .

 (3) Put an 80% partial reflector on that mount to pick off ~200mW for the doubling . One can find the reflector on my desk.

 (4) Put some steering mirrors to guide the transmitted beam through the reflector to the doubling crystal. Any beam path is fine if it does not disturb any other setups. The position of the oven+crystal should not be changed so much, I mean the current position looks good.

 (5) Match the mode to the crystal by putting some lenses. The optimum conversion efficiency can be achieved with beam waist of w0~50um (as explained on #2735). 

 (6) Align the oven by using the kinematic mount. It takes a while. The position of the waist should be 6.7 mm away from the center of the crystal (as explained on #2850). The temperature controller for the oven can be found in one of the plastic box for the green stuff. After the alignment, a green beam will show up.

(8) Find the optimum temperature which gives the best conversion efficiency and measure the efficiency.

(7)  Align the axis of the PSL beam to the MC by steering the two mirrors attached on the periscope.

  8130   Thu Feb 21 16:53:37 2013 ManasaUpdatePSLPSL shutter

[Steve, Jenne, Yuta, Manasa]

We have kept the laser ON at low power through the pump down process. As we pumped down, at around 400torr, we found that the PSL mech shutter closed. Steve explained  that it was due to an interlock with a pressure gauge. To keep the IFO running, we switched the shutter from N.C (normally close) to N.O (normally open). This should be undone after the pumpdown.

In the process of figuring out, we reset the shutter and switched it ON and OFF a couple of times.

  13962   Thu Jun 14 13:29:51 2018 gautamUpdateGeneralPSL shutter closed, all optics misaligned

[jon, gautam]

Jon is doing some characterization of the AUX laser setup for which he wanted only the prompt retroreflection from the SRM on the AS table, so the PSL shutter is closed, and both ITMs and ETMs are misaligned. The prompt reflection from the SRM was getting clipped on something in vacuum - the ingoing beam looked pretty clean, but the reflection was totally clipped, as I think Johannes aligned the input beam with the SRM misaligned. So the input steering of the AUX laser beam into the vacuum, and also the steering onto AS110, were touched... Also, there were all manner of stray, undumped beams from the fiber on the AS table noJon will post photos.

Before we began this work, we found that c1susaux was dead so we rebooted it.

  14515   Wed Apr 3 18:35:54 2019 gautamUpdateVACPSL shutter re-opened

PSL shutter was re-opened at 6pm local time. IMC was locked. As of 10pm, the main volume pressure is already back down to the 8e-6 level.

  14575   Thu Apr 25 11:27:11 2019 gautamUpdateVACPSL shutter re-opened

This activity seems to have closed the PSL shutter (actually I'm not sure why that happened - the interlock should only trip if P1a exceeds 3 mtorr, and looking at the time series for the last 2 hours, it did not ever exceed this threshold). I saw no reason for it to remain closed so I re-opened it just now.

I vote for not remotely rebooting any of the vacuum / PSL subsystems. In the event of something going catastrophically wrong, someone should be on hand to take action in the lab.

  15420   Fri Jun 19 19:21:25 2020 gautamUpdateGeneralPSL shutter re-opened

The PSL shutter was closed from the vacuum interlock trip. Today, I did the following:

  • Re-aligned input beam to PMC to recover high transmission / low reflection.
  • Re-set the LSC offsets.
  • ETMX watchdog was tripped. Reset it.
  • Opened the PSL shutter, IMC autolocker was able to lock the cavity almost immediately.
  • Tested POX/POY locking, ran the ASS to maximize single arm transmission.

All looks good for now. I will probably get back to PRFPMI locking Monday.

  16277   Thu Aug 12 11:04:27 2021 PacoUpdateGeneralPSL shutter was closed this morning

Thu Aug 12 11:04:42 2021 Arrived to find the PSL shutter closed. Why? Who? When? How? No elog, no fun. I opened it, IMC is now locked, and the arms were restored and aligned.

  16278   Thu Aug 12 14:59:25 2021 KojiUpdateGeneralPSL shutter was closed this morning

What I was afraid of was the vacuum interlock. And indeed there was a pressure surge this morning. Is this real? Why didn't we receive the alert?

Attachment 1: Screen_Shot_2021-08-12_at_14.58.59.png
Screen_Shot_2021-08-12_at_14.58.59.png
  16279   Thu Aug 12 20:52:04 2021 KojiUpdateGeneralPSL shutter was closed this morning

I did a bit more investigation on this.

- I checked P1~P4, PTP2/3, N2, TP2, TP3. But found only P1a and P2 were affected.

- Looking at the min/mean/max of P1a and P2 (Attachment 1), the signal had a large fluctuation. It is impossible to have P1a from 0.004 to 0 instantaneously.

- Looking at the raw data of P1a and P2 (Attachment 2), the value was not steadily large. Instead it looks like fluctuating noise.

So my conclusion is that because of an unknown reason, an unknown noise coupled only into P1a and P2 and tripped the PSL shutter. I still don't know the status of the mail alert.

Attachment 1: Screen_Shot_2021-08-12_at_20.51.19.png
Screen_Shot_2021-08-12_at_20.51.19.png
Attachment 2: Screen_Shot_2021-08-12_at_20.51.34.png
Screen_Shot_2021-08-12_at_20.51.34.png
  13264   Mon Aug 28 23:22:56 2017 johannesUpdatePSLPSL table auxiliary NPRO

I moved the axuiliary NPRO to the PSL table today and started setting up the optics.

The Faraday Isolator was showing a pretty unclean mode at the output so I took the polarizers off to take a look through them, and found that the front polarizer is either out of place or damaged (there is a straight edge visible right in the middle of the aperture, but the way the polarizer is packaged prevents me from inspecting it closer). I proceeded without it but left space so an FI can be added in the future. The same goes for the broadband EOM.

There are two spare AOMs (ISOMET and Intraaction, both resonant at 40MHz) available before we have to resort to the one currently installed in the PSL.

I installed the Intraaction AOM first and looked at the switching speed of its first order diffracted beam using both its commercial driver and a combination of minicircuits components. Both show similar behavior. The fall time of the initial step is ~110ns in both cases, but it doesn't decay rapidly no light but a slower exponential. Need to check the 0 order beam and also the other AOM.

Intraaction Driver

   

Mini Circuits Drive

   

  13270   Tue Aug 29 20:04:09 2017 ranaUpdatePSLPSL table auxiliary NPRO

I don't understand why the 1st order diffracted beam doesn't go to zero when you shut off the drive. My guess is that the standing acoustic wave in the AO crystal needs some time to decay: f = 40 MHz, tau = 1 usec... Q ~ 100. Perhaps, the crystal is damped by the PZT and ther output impedance of the mini-circuits switch is different from the AO driver.

In any case, if you need a faster shut off, or want something that more cleanly goes to zero, there is a large (~1 cm) aperture Pockels cell that Frank Siefert was using for making pulses to damage photo diodes. There is a DEI Pulser unit near the entrance to the QIL in Bridge which can drive it.

  13271   Tue Aug 29 21:36:59 2017 johannesUpdatePSLPSL table auxiliary NPRO
Quote:

 there is a large (~1 cm) aperture Pockels cell that Frank Siefert was using for making pulses to damage photo diodes. There is a DEI Pulser unit near the entrance to the QIL in Bridge which can drive it.

I'll look for it tomorrow, but I haven't given up on the AOMs yet. I swapped in the ISOMET modulator today and saw the same behavior, both in 0th and 1st order. The fall time is pretty much identical. Gautam saw no such thing in the PSL AOM using the same photodetector.

1st order diffracted                                                          0th order

     

In the meantime I prepared the fiber mode-matching but realized in the process that I had mixed up some lenses. As a result the beam did not have a waist at the AOM location and thus didn't have the intended size, although I doubt that this would cause the slower decay. I'll fix it tomorrow, along with setting up the fiber injection, beat note with the PSL, and routing the fiber if possible.

  13298   Tue Sep 5 23:13:44 2017 johannesUpdatePSLPSL table auxiliary NPRO

I used Gautam's mode measurement of the auxiliary NPRO (w=127.3um, z=82mm) for the spacing of the optics on the PSL table for the fiber injection and light modulation. As mentioned in previous posts, for the time being there is no Faraday isolator and no broadband EOM installed, but they're accounted for in the mode propagation and they have space reserved if desired/required/available.

The coupler used for the injection is a Thorlabs F220APC-1064, which allegedly collimates the beam from the fiber type we use to 2.4mm diameter, which I used as the target for the mode calculations. I coupled the first order diffracted beam to a ~60m fiber, which is a tad long but the only fiber I could locate that was long enough. The coupling efficiency from free-space to fiber is 47.5%, and we can currently get up to 63 mW out of the fiber.

Tomorrow Steve and I are going to pull the fiber through protective tubing and bring it to the AS port. The next step is then characterizing the beam out of the collimator to match it into the interferometer.

As far as the switching itself is concerned: I confirmed that the exponential decay is still present when looking at the fiber output. I located the DEI Pulser unit in the QIL lab, and also found several more AOMs, including a 200MHz Crystal Technologies one, same brand that the PSL has, where the ringdown was not observed. According to past elogs, with good polarizers we can expect an extinction ratio of ~200 from the Pockels cell, which should be fine, but it's going to be tradeoff switching speed <-> extinction (if the alternate AOM doesn't show this ringdown behavior).

Attachment 1: PSL_IR.pdf
PSL_IR.pdf
Attachment 2: psl_aux_laser.pdf
psl_aux_laser.pdf
  13301   Thu Sep 7 23:09:00 2017 johannesUpdatePSLPSL table auxiliary NPRO

I brought the DEI Pulser unit and a suitable Pockels cell over from Bridge today (I also found an identical Pockels cell already at the 40m on the SP table, now that I knew what to look for).

I also brought the 200MHz AOM (Crystal Technology 3200-1113) along which can achieve rise times of 10 ns(!). Before I start setting up the Pockels cell I wanted to try this different AOM and look at its switching behavior. It asks for a much smaller beam (<65 um diam.) than what's currently in the path to the fiber (500 um diam.), although it's clear aperture is technically big enough (~1mm diam.). So I still tried, and the result was a somewhat elliptical deflected beam, and the slower decay was again visible after switching the RF input.

I was using the big Fluke function generator for the 200MHz seed signal, a Mini Circuits ZASWA-2-50 switch and a Mini Circuits ZHL-5W-1 amplifier. For the last two I moved two power supplies (+/-5V for the switch and +24V for the amplifier) into the PSL enclosure. I started at low seed power on the Fluke, routing the amplified signal into a 20dB attenuator before measuring it with an RF power meter. The AOM saturates at 2.5W (34 dBm), which I determined is achieved with a power setting on the Fluke of -4 dBm. As expected, this AOM performed faster (~80ns fall time) but I again observed the slower decay.

This struck me as weird and I started swapping components other than the AOM, which I probably should have done before. It turned out that it was the PD I was using (the same PDA10CF Gautam had used for his MC ringdown investigations). When I changed it to a PDA10A (Si diode, 150MHz bandwidth) the slow decay vanished! One last round of crappy screenshots:

   

Rather than proceeding with the Pockels cell, tomorrow I will make the beam in the AOM smaller and hope that that takes care of the ellipticity. If it does: the AOM can theoretically switch on ~10ns timescale, same for the switch (5-15ns typical), and the amplifier is non-resonant and works up to 500MHz, so it shouldn't be a limiting factor either. If this doesn't work out, we can still have ~100ns switching times with the other AOMs.

  13306   Mon Sep 11 12:40:32 2017 johannesUpdatePSLPSL table auxiliary NPRO

I changed the PSL table auxiliary laser setup to the 200 MHz AOM and put the light back in the fiber. Coupling efficiency is again ~50%, giving us up to about 75 mW of auxiliary laser light on the AS table. The 90% to 10% fall time of the light power out of the fiber when switched off is 16.5 ns with this AOM on the PDA10A, which will be sufficient for the ringdown measurements.

  3743   Tue Oct 19 22:37:28 2010 KojiUpdatePSLPSL table cleaning up

I cleaned up the scattered tools, optics, and mounts of the PSL table. I gathered those stuffs at the two coners.

At the end of the work I scanned the table with an IR viewer. (This is mandatory)
I put some beam block plates to kill weak stray beams.

One thing I like to call the attention is:

I found that some beam blocks were missing at around the PBSs just after the laser source.
Those PBSs tend to reject quite a lot of beam power
--- no matter how the HWPs/QWPs are arranged.

--- even at the backward side.
(remember that we have a faraday there.)

Particularly, there was no beam block at the forward rejection side of the first PBS where we dump the high power beam.

Be careful. 

  3333   Fri Jul 30 14:53:09 2010 steveUpdateGeneralPSL table leg upgrade

Quote:

July
29 Thu BS chamber work: Move cable towers / green steering mirrors / (2 TTs with TT charactrization) / Put the heavy door by 5PM.
30 Fri Pumping down
31 Sat WFS work by Nancy

Aug
1 Sun - 5 Thu WFS work by Nancy
5 Thu PSL Table prep
6 Fri PSL Table prep / Likely to shut down the PSL

9 Mon PSL Table prep / shutting down of the PSL (optional)
10 Tue PSL box Frame lifting
12 Thu PSL table tapping

16 Mon - 17 Tue concrete pouring preparation
19 Thu - 23 Fri Tripod placement
24 Tue - 26 Thu concrete pouring

The PSL table height will be raised to the level of the AP table. This will be done using 6 TMC's Rigid Damped Tripod legs. Their planed positions shown below.

The legs will be grouted to the floor with concrete.

 http://www.techmfg.com/products/floorplatforms/rigiddampedtripod.htm

Attachment 1: psllegs.PDF
psllegs.PDF
  10780   Thu Dec 11 12:50:12 2014 manasaSummaryGeneralPSL table optical layout

 I assembled the telescope to couple PSL light into the fiber. The maximum coupling that I could obtain was 10mW out of 65mW (~15%).

I was expecting to achieve 80-90% coupling from my design estimates. It makes me wonder if the beam waist measurements made by Harry during summer were correct in the first place. I would like to go back and check the beam waist at the PSL table.

Also, we need a pair of 8m (~25 feet) long SMA cables to carry the RF signal from the beat PD on the PSL table to frequency counter module on the IOO rack.

Steve says that we had a spool of SMA cable and it was borrowed by someone a few months ago. Any updates on either who is holding it or if it has been used up already would help.


The X end slow computer was down this morning. So I used only the Y arm ALS to record the noise level for reference. DTT data for ALSY out of loop noise before opening PSL enclosure is saved in /users/manasa/data/141211/ALSYoutLoop.xml

  10787   Thu Dec 11 23:34:06 2014 manasaSummaryGeneralPSL table optical layout

Quote:

 I assembled the telescope to couple PSL light into the fiber. The maximum coupling that I could obtain was 10mW out of 65mW (~15%).

I was expecting to achieve 80-90% coupling from my design estimates. It makes me wonder if the beam waist measurements made by Harry during summer were correct in the first place. I would like to go back and check the beam waist at the PSL table.

Also, we need a pair of 8m (~25 feet) long SMA cables to carry the RF signal from the beat PD on the PSL table to frequency counter module on the IOO rack.

Steve says that we had a spool of SMA cable and it was borrowed by someone a few months ago. Any updates on either who is holding it or if it has been used up already would help.


The X end slow computer was down this morning. So I used only the Y arm ALS to record the noise level for reference. DTT data for ALSY out of loop noise before opening PSL enclosure is saved in /users/manasa/data/141211/ALSYoutLoop.xml

 I missed to elog this earlier. I have temporarily removed the DC photodiode for GTRY to install the fiber holder on the PSL table. So GTRY will not be seeing anything right now.

 

  10788   Fri Dec 12 02:30:25 2014 JenneSummaryGeneralPSL table optical layout

Quote:

 

 I missed to elog this earlier. I have temporarily removed the DC photodiode for GTRY to install the fiber holder on the PSL table. So GTRY will not be seeing anything right now.

 

 After some confusion, I discovered this a few hours ago.

  2051   Mon Oct 5 13:43:37 2009 ZachUpdatePSLPSL table photos

I have been commissioned to take pictures of the PSL table so that it can be diagrammed. I am starting now (1:42 pm, 10/5/09).

  2052   Mon Oct 5 14:18:41 2009 ZachUpdatePSLPSL table photos

Quote:

I have been commissioned to take pictures of the PSL table so that it can be diagrammed. I am starting now (1:42 pm, 10/5/09).

All done (for now). That wasn't so bad, was it?

  13632   Tue Feb 13 22:35:21 2018 gautamUpdateElectronicsPSL table power supply cleanup

The main motivation for this work is that I want +15VDC power available on the PSL table to hookup the Teledyne box that Koji made a week ago and do some noise measurements on my revised IR ALS signal chain. But I think this is a good opportunity to effect a number of changes I've been wanting to do for a while.

Tomorrow, Steve and I will do the following:

  1. Fix the AOM driver power cabling that I broke.
  2. Make the AOM +24VDC power supply independent - right now it is shared between the AOM driver and the two ZHL-3-A amplifiers.
  3. Tap an independent +24VDC power supply from 1X1 for the ZHL-3A amplifiers (I guess one power supply and fuse is sufficient for both amplifiers since they are in the same box).
  4. Tap an independent +15VDC power supply for the Teledyne box.
  5. Tap an independent +15VDC power supply for the little fan on the back of the PSL controller, that is currently powered by a bench supply (+12VDC, but it's just a fan, so +15VDC or +10VDC will do just fine, and these are the Sorensen levels we have).
  6. Tap an independent +/-24VDC power supply for the FSS summing box. Right now it is being powered by a bench supply under the PSL table. The indicated supply voltage on the box is +/-18V. But according to the schematic, this +/-18V get regulated down to +/- 15V, so we may as well use +/-24V which is available from the Sorensens in 1X1 (there is no +/-18VDC Sorensen there). The datasheets for the 7815 and 7915 ICs suggest that this will be just fine.
  7. Where possible, make at least 1 spare outlet for each supply voltage available at 1X1, such that in future, tapping extra supply points won't be such a huge pain.

So in summary, we will need, at 1X1, (at least, including 1 spare for future work):

  • New +24VDC connections ------ 3x
  • New -24VDC connections ------- 2x
  • New +15VDC connections ------ 3x
  13633   Wed Feb 14 17:49:22 2018 gautamUpdateElectronicsPSL table power supply cleanup

[steve, gautam]

We completed this work today. Need to clean up a little (i.e. coil excess cable lengths, remove unused cables etc), which we will do tomorrow. All connections have been made at the DIN rail end, but the fuses have not been inserted yet, so there is no voltage reaching the PSL table on any of the newly laid out cables. We also need to establish two +15VDC connections at the DIN rail side. I may establish this later in the evening, as the main point of this work was to get the Teledyne signal path operational. Setting up these DIN connectors is actually a huge pain, we tried to setup a few extra ports for the voltages we used today so that in future, life is easier for whoever wants to pipe DC power to the PSL table. The rule is, however, to re-establish the same number of open ports for each voltage as was available when you started.

For the ZHL-3A, Teledyne, and AOM driver cables, we used 18AWG, 2 conductor, twisted wire, while for the PSL fan we used 20AWG. For the FSS box, we decided to use the 3 conductor 24AWG twisted wire. I believe that these wire gauge choices are appropriate given the expected current in each of these paths.

Pictures + further details tomorrow.

gautam @ 1030pm: there was some mistake with the +15V wiring we did in the evening (the PSL fan and Teledyne cables were plugged into the wrong DIN terminal blocks). I fixed this, and also routed +15VDC to the newly installed set of terminal blocks for this purpose (since we had run out of +15VDC ports at 1X1). After checking voltages at both 1X1 and on the PSL table, I hooked up

  1. FSS Summing box
  2. Teledyne amplifier
  3. ZHL-3A amplifiers

to their newly laid out power supplies. IMC locks so looks like the FSS box is doing fine yes. So we can recover one bench power supply from under the PSL table on the east side. I didn't hook up the AOM driver just now because of some accessibility issues, and I'd also like to do an ALS beat spectrum measurement if possible.

Attachment 1: IMG_5135.JPG
IMG_5135.JPG
Attachment 2: Sorensens_1X1_before.JPG
Sorensens_1X1_before.JPG
Attachment 3: Sorensens_1X1_after.JPG
Sorensens_1X1_after.JPG
  3487   Mon Aug 30 13:57:25 2010 KojiSummaryPSLPSL table vibrational performance after the upgrade

Jenne and Koji

Last week Jenne has put the accelerometers on and under the PSL table immediately after the plastic sheets were removed.

So I took the same measurement as I did on 9th Aug.

Here is the comparison of the vibrational performance of the table before and after the modification.

Basically the table is now stiffer and more damped than it was before.
We don't find any eminent structure below (at least) 70Hz.

This result is obtained despite elevating of the table.

1) Attachment 1

For the horizontal comparison (top),  it is clearly seen that the large resonant peak at 20Hz was eliminated.
At least the new resonances went up to 70-90Hz region. Y is basically equivalent to X.

For the vertical comparison (bottom), it is clearly seen that the resonant peaks at around 50 & 70Hz were eliminated. 
At least no new resonance is seen.

2) Attachment 2

All-in-one plot for the measurement --- spectra, coherences, transfer functions --- after the upgrade. I put the same plot for the one before the upgrade.

Attachment 1: PEM_100830_SPE.pdf
PEM_100830_SPE.pdf
Attachment 2: PEM_100830.pdf
PEM_100830.pdf PEM_100830.pdf
  108   Thu Nov 15 18:36:48 2007 JohnSummary PSL table work
I've rotated the lambda/2 plate to 340deg (from 6 deg) and blocked one arm of the Mach-Zender. Undo both if you need to.
  5069   Sat Jul 30 10:01:35 2011 JennyUpdatePSLPSL table work

I've been working on the PSL table to put together a setup so that I can measure the reference cavity's response to a temperature step increase at the can surrounding it. My first step was to mode match the beam coming from the AP table to the cavity.

I implemented my mode matching solution. I ended up using a different one from the one I last elogged about. Here is the solution I used:

Two lenses: f = 1016.7.6 mm at -0.96 m and f = 687.5 mm at -0.658 m. (I set my origin at the polarizing beam splitter--the spot where I want my beam to match the beam coming from the PMC, so all waists are behind that point). Below is what it should look like.

modematchpic.pngmodematchinfo.png

What I did on the table:

  • Before placing lenses I aligned the beam and added a 1/2-wave plate between the two polarizing beam splitters to change the polarization of the beam from S to P.
  • I aligned the beam so that it reflected off of the cavity opening (monitoring the reflected power with a photodetector connected to an oscilloscope and tweaking the alignment to maximize the reflected signal). 
  • I then placed the lenses at -0.93 and -0.64 mm because the exact spots were blocked by optics being used in another setup.
  • I reasoned that since the fitting for the initial waist is so uncertain, the lens position being off by a few cm will not produce the dominating source of error. I am now driving the laser frequency using a lock-in as a function generator to drive the laser temperature at ~1 Hz. I'm then monitoring the power transmitted by the reference cavity with a camera connected to a TV monitor. I will use this setup to improve my mode matching.

Here's a picture of the PSL table with the lenses and mirror I added. The beam is redirected by a mirror and then a polarizing beam splitter. Past the beam splitter is another lens (f=286.5 mm), which was already in place from the mode matching of the beam from the PMC to the reference cavity.

modematch_setup_pic.png

Here is a block diagram of my intended experimental setup:

LIGO_block_diagram.png

I am going to try to lock the laser to the cavity given my preliminary mode matching and then go back and improve it later. My next step is to find a frequency range for dithering the voltage sent to the PZT. To do this I will:

  • Measure the transfer function (amplitude response) of the PZT using a photodiode. The power outputted by the laser varies with driving frequency.
  • Find a frequency region in which the amplitude response is low.
Attachment 3: LIGO_block_diagram.png
LIGO_block_diagram.png
  9252   Thu Oct 17 22:38:25 2013 MasayukiUpdatePSLPSL temperature changed

[Manasa, Masayuki]

PSL temperature changed

The beat note of Xarm looked somehow strange before (elog). It should be the highest when the green transmission power is highest, in other words when the end green PDH locks with a TEM00 mode. But it was not like that. When the end PDH locked with other modes (GTRX: below 0.3), the beat note was higher than TEM00 mode (GTRX: around 0.5). 

We guessed that end green laser was somewhere around the point where there were 2 stable TEM00 modes . In order to move away from this unstable region of the end laser, we changed PSL temperature to obtain beat note at a different green laser frequency where we do not have any of the weird modes oscillating.

We changed the PSL temperature from 31.63 degree to 31.33 degree. We measured the in-loop noise of ALS loop and I attached it. There is not big difference in Yarm, but the Xarm in-loop noise become better in high frequency region. We think before the xend green laser was in a not-so-good state and the laser had more frequency noise then. 

ALS stability

After change PSL temperature, Xarm ALS is so stable. Actually Xarm is being locked right now and it is locked for more than 50 minutes!!
Although the Xarm ALS is so stable, Yarm ALS is not stable right now. It lost lock by ~5min. We don't know what is the reason, so we will try to fix it tomorrow.

Attachment 1: in-loop.pdf
in-loop.pdf
  14605   Mon May 13 10:45:38 2019 gautamUpdatePSLPSL turned ON again

I used some double-sided tape to attach a San Ace 60 9S0612H4011 to the Innolight controller (Attachment #1). This particular fan is rated to run with up to 13.8V, but I'm using a +15V Sorensen output - at best, this shortens the lifespan of the fan, but I don't have a better solution for now. Then I turned the laser on again (~1040 local time), using the same settings Rana configured earlier in this thread. PMC was locked, and the IMC also could be locked but I closed the shutter for now while the laser frequency/intensity stabilizes after startup. The purpose is to facilitate completion of the pre-vent alignment checklist in prep for the planned vent tomorrow. PMC Trans reports 0.63 after alignment was optimized, which is ~15% lower than in Oct 2016.

Attachment 1: IMG_7431.JPG
IMG_7431.JPG
  14609   Wed May 15 10:56:47 2019 gautamUpdatePSLPSL turned ON again

To test the hypothesis that the fan replacement had any effect on the NPRO shutoff phenomena, I turned the HEPA on the PSL table down to the nominal 30% setting at ~10am.

Tomorrow I will revert the laser crystal temperature to whatever the nominal value was. If the NPRO runs in that configuration (i.e. the only change from March 2019 are the diode TEC setpoints and the new fan on the back of the controller), then hurray.

  14595   Mon May 6 10:51:43 2019 gautamUpdatePSLPSL turned off again

As we have seen in the last few weeks, the laser turned itself off after a few hours of running. So bypassing the lab interlock system / reverting laser crystal temperature to the value from Innolight's test datasheet did not fix the problem.

I do not understand why the "Interlock" and "TGUARD" channels come revert to their values when the laser was lasing a few minutes after the shutoff. Is this just an artefact of the way the diagnostics is set up, or is this telling us something about what is causing the shutoff?

Attachment 1: NPROshutoff.png
NPROshutoff.png
  14599   Thu May 9 19:50:04 2019 gautamUpdatePSLPSL turned off again

This time, it stayed on for ~24 hours. I am not going to turn it on again today as the crane inspection is tomorrow and we plan to keep the VEA a laser safe area for speedy crane inspection.

But what is the next step? If these diode temps maximize the power output of the NPRO, then it isn't a good idea to raise the TEC setpoint futher, so should I just turn it on again with the same settings?

I did not turn the HEPA down on the PSL enclosure. I also turned off the NPROs at EX and EY so now all the four 1064nm lasers in the VEA are turned OFF (for crane inspection).

Quote:

locked PMC at 1900 PT; let's see how long it lasts.

My hunch is that the TECs are working too hard and can't offload the heat onto the heat sinks. As the diode's degrade, more of the electrical power is converted to heat in the diodes rather than 808 nm photons. So hopefully the increased airflow will help

 
Attachment 1: Screenshot_from_2019-05-09_19-49-29.png
Screenshot_from_2019-05-09_19-49-29.png
  14583   Mon Apr 29 16:25:22 2019 gautamUpdatePSLPSL turned on again

I turned the 2W NPRO back on again at ~4pm local time, dialing the injection current up from 0-2A in ~2 mins. I noticed today that the lasing only started at 1A, whereas just last week, it started lasing at 0.5A. After ~5 minutes of it being on, I measured 950 mW after the 11/55 MHz EOM on the PSL table. The power here was 1.06 W in January, so ~💯  mW lower now. 😮 

I found out today that the way the python FSS SLOW PID loop is scripted, if it runs into an EZCA error (due to the c1psl slow machine being dead), it doesn't handle this gracefully (it just gets stuck). I rebooted the crate for now and the MC autolcoker is running fine again. 

NPRO turned off again at ~8pm local time after Anjali was done with her data taking. I measured the power again, it was still 950mW, so at least the output power isn't degrading over 4 hours by an appreciable amount...

  14593   Fri May 3 12:51:58 2019 gautamUpdatePSLPSL turned on again

Per instructions from Coherent, I made the some changes to the NPRO settings. The value we were operating at is in the column labelled "Operating value", while that in the Innolight test datasheet is in the rightmost column. I changed the Xtal temp and pump current to the values Innolight tested them at (but not the diode temps as they were close and they require a screwdriver to adjust), and turned the laser on again at ~1245pm local time. The acromag channels are recording the diagnostic information.

update 2:30pm - looking at the trend, I saw that D2 TGuard channel was reporting 0V. This wasn't the case before. Suspecting a loose contact, I tightened the DSub connectors at the controller and Acromag box ends. Now it too reports ~10V, which according to the manual signals normal operation. So if one sees an abrupt change in this channel in the long trend since 1245pm, that's me re-seating the connector. According to the manual, an error state would be signalled by a negative voltage at this pin, up to -12V. Also, the Innolight manual says pin 13 of the diagnostics connector is indicating the "Interlock" state, but doesn't say what the "expected" voltage should be. The newer manual Coherent sent me has pin13 listed as "Do not use".

Setting Operating value Value Innolight tested at
Diode 1 temp [C] 20.74 21.98
Diode 2 temp [C] 21.31 23.01
Xtal temp [C] 29.39 25.00
Pump current [A] 2.05

2.10

  14597   Wed May 8 19:04:20 2019 ranaUpdatePSLPSL turned on again
  1. Increased PSL HEPA Variac from 30 to 100% to get more airflow.
  2. All of the TEC setpoints seem cold to me, so I increased the laser crystal temperature to 30.6 C
  3. Adjusted the diode TEC setpoints individually to optimize the PMC REFL power (unlocked). DTEC A = 22.09 C, DTEC B = 21.04 C
  4. locked PMC at 1900 PT; let's see how long it lasts.

My hunch is that the TECs are working too hard and can't offload the heat onto the heat sinks. As the diode's degrade, more of the electrical power is converted to heat in the diodes rather than 808 nm photons. So hopefully the increased airflow will help.

I tried to increase the DTEC setpoints, but that seems to detune them too far from the laser absorption band, so that's not very efficient for us. IN any case, if we end up changin the laser temperature, we'll have to adjust the ALS lasers to match, and that will be annoying.

 

The office area was very cold and the HVAC air flow stronger than usual. I changed the setpoint on the thermostat near Steve's desk from 71 to 73F at 1830 today.

  3543   Wed Sep 8 09:50:13 2010 ranaUpdatePSLPSL update

Also, Kiwamu has modified the layout drawing to add the green PLL stuff. This has collapsed the reference cavity's wave function placing it close to its original position.

WE (maybe Valera and Steve) can now put the reference cavity back on the table.

  3558   Sat Sep 11 22:42:07 2010 valeraUpdatePSLPSL update

- The PMC REFL PD was moved from the temporary location to the one called for by the PSL layout (picture attached). The leakage beams were dumped.

- The FSS reference cavity was aligned using temporary periscope and scanned using NPRO temperature sweep. The amplitude of the sweep (sine wave 0.03 Hz) was set such that the PMC control voltage was going about 100 V p-p with. With rough alignment the visibility was as high as 50% - it will be better when the cavity is locked and better aligned but not better than 80% expected from the mode astigmatism that Tara and I measured on Thursday. The astigmatism appear to come from the FSS AOM as it depends on the AOM drive. We reduced the drive control voltage from 5 V to 4V beyond that the diffraction efficiency went below 50%. The FSS REFL PD was set up for this measurement as shown in the attached picture. There is also a camera in transmission not shown in the picture.

Attachment 1: DSC_2502.JPG
DSC_2502.JPG
Attachment 2: DSC_2505.JPG
DSC_2505.JPG
  3523   Fri Sep 3 23:42:34 2010 JenneUpdatePSLPSL update of the day

Rana and I were poking around on the PSL table today, getting a few more items raised to the correct height.

I checked the polarization state of the new NPRO by using a HWP to minimize the transmission through a PBS cube, and then compared the power transmitted through the cube vs. reflected.  When the NPRO current was 0.772 \pm 0.001 (as read on the LCD), the transmission through the cube was 1.44mW, while the reflected was 10.53mW.  The reading of the Ophir power meter with no incident light was 0.03mW.  This factor of 10 means that the NPRO beam is ~10% circularly polarized and ~90% linearly polarized.  In order to improve the beam, we need a Quarter Wave Plate, which it turns out we don't have.  We need a QWP!

After that, using the linearly polarized part of my beam (maximizing the transmission through the PBS by rotating my HWP by 45deg), I tried to tune the angle of the polarizers that Rana pulled out of the MOPA.  I think I'm confused / too tired, because I can only get the polarizer to reflect a bunch of light, and I can't get it to pass any significant amount of light through, no matter where in its actuation range I put it (It's on a rotation stage with a few degrees of range).  It should just be a Brewster's Angle thing, and since I already have P-pol coming through the BS cube, this shouldn't be so hard.....

In any case, it may not be useful to do the final fine tuning of these polarizers until they are in their final places.  The hacky stack of mounts that I have has some slop in the position / alignment of the base of the polarizer, so no matter what we'll have to redo the tuning after the mounts are finalized.

  3525   Mon Sep 6 01:46:58 2010 ranaUpdatePSLPSL update of the day

To bypass the polarizer issue, I just used cubes. One I took from the FSS-Refcav path and the other from the power control part of the old MOPA, just downstream of the MOPA's periscope.

We'll swab these out with the thin-film polarizers after we get the mounts made.

With the cubes in, I also installed the Faraday + its 1/2-wave plate. The transmission looks good and we're getting into the PMC and its flashing a TEM00 mode sometimes. I set up a signal generator to drive the SLOW actuator by 1 FSR at 0.1 Hz.

I have set up a PMC transmission camera and transPD so that its easy to align. The flashing mode already allows us to align most of the rest of the table (except FSS).

Our next step should be to run the cables for locking the PMC:

  1. RF cables to the PMC_REFL
  2. Dsub for the PMC RFPD
  3. HV cable between the PMC servo board and the PMC PZT (why is this not RED? we have to make sure to abide by the cabling color code).
  4. RF cable from 35.5 MHz Frequency Reference card to the PMC EOM via the RF summing box on the table.

On Tuesday, we need to make sure that all of our mounts' drawings are in the cue for the shop. I'll put the list of mounts onto the PSL upgrade wiki page.

We also have to come up with a plan for wiring some of the 2W NPRO's channels into the cross-connect so that we can have some laser channels recorded by EPICS.

ELOG V3.1.3-