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ID Date Author Type Category Subjectup
  5721   Fri Oct 21 11:02:47 2011 steveUpdatePSLPSL laser turned ON

Quote:

In order to move the emergency shut off switch in room 103 I had to turn off the 2 W Innolight laser. This job will take an hour.

 

 It is back on.

  5720   Fri Oct 21 10:32:14 2011 steveUpdatePSLPSL laser turned off

In order to move the emergency shut off switch in room 103 I had to turn off the 2 W Innolight laser. This job will take an hour.

 

  4977   Fri Jul 15 17:42:21 2011 SonaliUpdateGreen LockingPSL layout for superposition of the PSL,ETMX and ETMY beams.

The fibres carrying the beams from the ETMX as well as the ETMY have been routed to the PSL table now.

A part of the PSL beam has to be superposed on the fibre-outputs to obtain a beat signal. We have located a stray beam on the PSL(which is currently being dumped) which we plan to redirect for the same. The layout of the plan is attached herewith.

  9997   Tue May 27 22:29:17 2014 JenneUpdatePSLPSL making noises

Also, while I was working on the PSL table, I heard noise that sounded like a bearing rolling around.  I suspected the HEPAs, since the one on the north east corner of the table has a problem when it's turned up high (we've known about this for a long time), however turning off the HEPAs didn't affect the noise.  The noise is strongest near the back of the PSL controller on the shelf above the table, and the PSL controller box is vibrating.  So, I suspect that the fan on the PSL controller box is about to give out.

EDIT:  To clarify, I mean the Innolight's controller.

  13212   Wed Aug 16 14:54:13 2017 gautamUpdateCDSPSL monitoring Acromag EPICS server restarted

[johannes, gautam, jamie]

  • Made a directory /opt/rtcds/caltech/c1/scripts/Acromag/PSL where I copied over the files needed my modbusApp to start the server from Lydia's user directory
  • Edited /ligo/apps/ubuntu12/ligoapps-user-env.sh to export a couple of EPICS variables to facilitate easy startup of the EPICS server
  • Started a tmux session on (soon to be re-christened?) megatron called "acroEPICS"
  • Ran the following command to start up the EPICS server:
${EPICS_MODULES}/modbus/bin/${EPICS_HOST_ARCH}/modbusApp npro_config.cmd

To do:

  1. Make a startup script that runs the above command - eventually this can contain the initialization instructions for all the Acromags
  2. Figure out the initctl/systemctl stuff to make the server automatically restart if it drops for some reason (e.g. power failure)
  13708   Tue Mar 27 01:39:44 2018 gautamUpdateIOOPSL noise eater was off

While Kevin and Arijit were doing their MC_REFL PD noise measurements (which they will elog about separately shortly), I noticed a feature around 600kHz that reminded me of the NPRO noise eater feature. This is supposed to suppress the relaxation oscillation induced peak in the RIN of the PSL. Surprisingly, the noise eater switch on the NPRO front panel was set to "OFF". Is this the normal operating state? I thought we want the noise eater to be "ON"? Have to measure the RIN on the PSL table itself with one of the many available pick off PDs. In any case, as Attachment #1 showed, turning the noise eater back on did not improve the excess IMC frequency noise.

  13711   Tue Mar 27 19:32:03 2018 arijitUpdateIOOPSL noise eater was off

Kevin, Gautam and Arijit

We made a measurement of the MC_REFL photodiode transfer function using the network analyzer. We did it for two different power input (0dB and -10dB) to the test measurement point of the MC_REFL photodiode. This was important to ensure the measurements of the transfer function of the MC_REFL photodiode was in the linear regime. The measurements are shown in attachment 1. We corrected for phase noise for the length of cable (50cm) used for the measurement. With reference to ELOG 10406, in comparison to the transimpedance measurement performed by Riju and Koji, there is a much stronger peak around 290MHz as observed by our measurement.


We also did a noise measurement for the MC_REFL photodiode. We did it for three scenarios: 1. Without any light falling on the photodiode 2. With light falling on the photodiode, the MC misaligned and the NPRO noise eater was OFF 3. With light falling on the photodiode, the MC misaligned and the NPRO noise eater was ON. We observed that the noise eater does reduce the noise being observed from 80kHz to 20MHz. This is shown in attachment 2.


We did the noise modelling of the MC_REFL photodiode using LISO and tried matching the expected noise from the model with the noise measurements we made earlier. The modeled noise is in good agreement with the measured noise with 10Ohms in the output resistance. The schematic for the MC_REFL photodiode however reveals a 50Ohm resistance being used. The measured noise shows excess noise ~ 290MHz. This is not predicted from the simplied LISO model of the photodiode we took.


Discussion with Koji and Gautam revealed that we do not have the exact circuit diagram for the MC_REFL photodiode. Hence the simplified model that was assumed earlier is not able to predict the excess noise at high frequencies. One thing to note however, is that the excess noise is measured with the same amplitude even with no light falling on the MC_REFL photodiode. This means that there is a positive feedback and oscillation in the op-amp (MAX4107) at high frequencies. One way to refine the LISO model would be to physically examine the photodiode circuit.

We also recorded the POX and POY RF monitor photodiode outputs when the interferometer arms are independently stabilized to the laser. Given the noise outputs from the RF photodiodes were similar, we have only plotted the POY RF monitor output for the sake of clarity and convenience.

Quote:

While Kevin and Arijit were doing their MC_REFL PD noise measurements (which they will elog about separately shortly), I noticed a feature around 600kHz that reminded me of the NPRO noise eater feature. This is supposed to suppress the relaxation oscillation induced peak in the RIN of the PSL. Surprisingly, the noise eater switch on the NPRO front panel was set to "OFF". Is this the normal operating state? I thought we want the noise eater to be "ON"? Have to measure the RIN on the PSL table itself with one of the many available pick off PDs. In any case, as Attachment #1 showed, turning the noise eater back on did not improve the excess IMC frequency noise.

 

  3394   Tue Aug 10 17:21:48 2010 steveUpdateGeneralPSL optical table is at 30" height

Mike Gerfen, Koji and Steve,

 

Our old ( 6 x 10 x 1 ) ft Newport optical table will have the same height as the neighboring AP table when this job is finished.

Today's work was to elevate the optical table ~ 2400 lbs to 30" clearance to create a workable space below.

 

Atm1,  enclosure frame was raised by 6"

Atm2,  2 pellet jacks and 4x4 technology in the work.

Atm3,  ready for drill and tap with jig plate in place, note 4 Al legs 8" OD. 1/4" wall safely supporting the load

Atm4,  showing clamps that holding 1/2" plywood with jigs

Atm5, We removed the 4 old legs: 6" OD steel, 1/4" wall and 10" high after they were unloaded.

  3472   Wed Aug 25 16:13:32 2010 steveSummaryPEMPSL optical table is back into operation at 32.75" level

The tile work was done yesterday after noon.

This morning Mike Gerfen and me lowered the enclosure frame to normal height.

Keven- janitor and I removed plastic covers from chambers, racks, SP, MC2 and clean tool boxes.

 

The afternoon Jenne, Kiwamu, Joe and Aiden cleaned the enclosure inside out. The particle count measured zero inside the enclosure with HEPAs on when the covers were

removed. The MOPA and all other components were happy to see us in excellent condition.

This table height is very user friendly!

 

Safety grounds were reconnected.

 

Atm1, new tiles around the concrete slab

Atm2, frame lowered with low cross bars reinstalled

Atm3, the enclosure frame's north west foot is connected to ground

Atm4, PSL optical table is connected to ground at the north east corner through 1 Mohm

Atm5, PSL optical table level at a stimulating, back-friendly height

  3435   Wed Aug 18 16:42:14 2010 steveUpdatePEMPSL optical table legs load balanced

 

 Rana, Koji, Alberto and Steve, Tuesday afternoon

 

Atm3, Part of the tunnel under the table was filled with quick drying concrete this morning  to give solid support for tripod legs.

          PVC tube 6 " ID with TEE will able us to connect AP table, PSL table and Control room if needed

Atm4, Table height set to equal AP at  ~32.75 " on copper plates using 5/8-11 x 4.5" set screw-bolt in tripod foot

           Rough leveling was done by 4 individual levels at the four corners with 9" long Stanley cast aluminum levels.

          Load balancing of the total weight  ~ 3000 lbs over  6 legs x3 = ~170 lbs on each jack screw with Snap-On torque wrench at 140 lbs/ft

Atm1, Three crew members at work. Prof. Rana's calibrated right hand was used at jack screws where insufficient space was available for socket head wrench.

Atm2, Table is ready for no shrink grouting now.

         

 

 

 

 

  3430   Tue Aug 17 14:09:15 2010 steveUpdatePEMPSL optical table schedule

Tuesday, 17 August : fill tunnel, set table height, level table and balance load

Wednesday : grout tripod legs and leave it alone

Thursday : built  guide-form for concrete

Friday :  pour concrete

Monday, 23 August : remove guide forms and clean up

  3698   Tue Oct 12 16:35:17 2010 steveConfigurationPSLPSL output monitor in place

Innolight PSL laser is set to @2.1A , ~1.6W output ! Please scan out when finished! 

The output monitoring pick up window W2-LW-2-2050-UV-1064-45S is in place. IOO_ANG_OPD and IOO_POS_QPD roughly aligned.

The PMC alignment and/ or mode matching is bad. PMC reflected is 50%, throughput 600mW

Remember to block PSL output ! into IFO

 

  2947   Tue May 18 15:09:02 2010 steveConfigurationSAFETYPSL output shutter in order again

Quote:

As we learned yesterday, the PSL laser power out put mechanical shutter is not working in the remote mode. It only works in local manual mode.

Do not rely on the MEDM screen monitor readout! The position is only changing on the monitor. The main beam must be blocked before the output periscope.

Ben found the Sorenson 5V ps off. It was turned off since our last scheduled power outage. I wonder what else is running on 5V in the PSL? This power supply should be on the

"alarm handler"  list to avoid future repeat of this condition. However a real safety switch would have confirming position sensors of the shutter open or closed. Is there such thing at the sites?

  9334   Mon Nov 4 11:37:12 2013 SteveUpdateIOOPSL output shutter installed

 

 The PSL shutter is reinstalled.The base plate is delrin for isolation and the mount height is adjustable. The last steering mirror mount to be swapped in is ready. It is sitting on the top of the ITMX optical table cover with SS dogs.

There are two reflected spots on the north side of the Uniblitz shutter. They are coming from the vacuum window. They should be trapped also.

  2589   Thu Feb 11 15:53:59 2010 steveConfigurationVACPSL output shutter is closed

Joe and Alex are working on the computers. Our vacuum system is temporary "All off" condition: meaning all valves are closed, so there is no pumping. cc1 = 1.6e-6 Torr

  10511   Tue Sep 16 17:02:41 2014 SteveUpdateComputer Scripts / ProgramsPSL output shutter is floating

Quote:

Quote:

Q and Steve will follow elog 10028 entry to prepare the vacuum system for safe reboot

Here's the sequence of the morning so far:

  • I aligned the IFO (IR arms with ASS, X green with PZTs, PRM with PRMI locked on REFL33)
  • I closed the PSL shutter, and went inside to align PRM and both ITM oplevs (all others were within 10urad of zero in both directions)
  • While aligning those oplevs, I noticed the smell of burnt electronics. We tracked it down to the +15V sorensen in the rack nearest the PSL table
    • I claim the precipitating event was PSL shutter activity. If I recall correctly, the seismic rainbow traces went bonkers around the same time as the shutter was closed. There is a Guralp interface in the rack powered by the failed sorensen, so this would explain the erratic seismometer signals correlated with the power supply failure. We will look into potential shorts caused by the shutter. (Steve looked up the PMC trans and Guralp DQ channels, and confirmed the temporal coincidence of the events.)
  • We shut off all of the sorensens so that electronics were not being driven asymmetrically. 
  • Steve and I secured the vacuum system for computer reboots, as referred to in Steve's elog. Some combination of Jenne, Rana and Manasa shut down the control room computers, and turned off the watchdogs. 
  • Manasa and I moved Chiara inside, next to Mafalda, along with its backup HDs. It has been labeled. 
  • Booted up control room machines, they came up happy. 
  • FB and front-ends didn't need reboot, for some lucky reason. Watchdogs came back happily, oplev spots didn't move noticeably. 

The IFO is still down, as the PMC won't lock without the rack power, and we haven't pinned down the shorting mechanism. We don't want the replacement sorensen to immediately blow when plugged in. 

 The Uniblitz shutter is insulated at the optical table. I only realized it when it was in my hand. The 3"x2" base plate is black DELRIN !

 In the future we must label black Delrin base plate where it is used. Now we have  white Delrin and light bran PEEK  base plates  for the same function.

  9545   Fri Jan 10 10:28:03 2014 SteveUpdatePSLPSL pointing changes

 

I looked at IOO QPDs again. QPD_POS was clamped by one screw. Dog clamp was added on the unclamped side.

QPD_ANG chassis has no isolation to optical table..._POS has.  QPD_ANG  base was tightened also.

Both QPDs moved a little bit but I did not centered them.  The spot sizes are 2-3 mm  They should be smaller.

How ever, we still can not explane the pitch movement of the IOO beam

 

Razor beam dumps were labeled at the AP table.

 

The 40m roof was cleaned from leafs this morning.

 

 

  9542   Thu Jan 9 10:34:58 2014 SteveUpdatePSLPSL pointing changes in pitch

  IOO QPDs tested in dark, lighted and open PSL enclosure. The created temperature change 0.03 C has  effect on monitoring  in pitch.

 

 Atm1,  all lights off 10 min, PSL enclosure lights on  10 min, all lights off 15 min, open  door # 11 at north east corner of enclosure ( HEPA filters are running at 30V ) for 10 min, closed-dark enclosure 15 min

              dark 10, lighted 10, dark 15, open-dark 10 and closed-dark 15 minutes

 

Atm2, Pitch drift of 24 hours does not recover

  9358   Thu Nov 7 08:57:20 2013 SteveUpdateIOOPSL pointing monitoring

 The qpd sees the power drop as position change.

The laser  monitoring screen shows little changes of the Innolight 2W output. See elog 9292 to compare

So why does the PMC downgrade if the laser output is stationary ?

The PMC-T power is down to 0.75V  The auto locker does maximize power output.

It needs a manual alignment touch up.

 

 

  9365   Mon Nov 11 22:35:45 2013 RANAUpdateIOOPSL pointing monitoring

Since the pointing has gone bad again, I went to the PSL to investigate. Found some bad things and removed them:

1) There was a stopped down iris AGAIN in the main beam path, after the newly installed mirror mount. I opened it. Stop closing irises in the beam path.

2) The beam dump for the IOO QPD reflection was just some black aluminum. That is not a real dump. I removed it. We need two razor blade dumps for this.

3) There was an ND filter wheel (???) after one of the PMC steering mirrors. This is not good noise / optics practice. I removed it and dumped the beam in a real dump. No elog about this ?!#?

 

The attached trend shows the last 20 days. The big step ~2 weeks ago is when Steve replaced the steering mirror mount with the steel one. I don't understand the drift that comes after that.

 

Today I also spent ~1 hour repairing the Aldabella laptop. Whoever moved it from the PSL area to the SP table seems to have corrupted the disk by improper shutdown. Please stop shutting the lid and disconnecting it from the AC power unless you want to be fixing it. Its now running in some recovery mode. Lets leave it where it is next to the PSL and MC1.

I steered the MC suspensions back to where they were on the trends before the PSL mirror mount swap and then aligned the PSL beam into it by touching the last 2 steel mounts. Once the alignment was good without WFS, I centered the beams on the IOO QPDs. If it behaves good overnight, I will center the unlocked beams on the MC WFS.

 

Please stay off the PSL for a couple days if you can so that we can watch the drift. This means no opening the doors, turning on the lights, or heavy work around there.

  9370   Tue Nov 12 23:48:23 2013 RANAUpdateIOOPSL pointing monitoring

Since I saw that the trend was good, I aligned the MC refl path to the existing IMC alignment:

  1. removed a broken IRIS that was clipping the reflected beam (and its mount)
  2. moved the first 1" diameter steering mirror on the high power path after the 2" diameter R=10% steering mirror. It was not centered.
  3. Moved the lens just upstream of the LSC RFPD away from the PD by ~5 mm. The beam going towards the WFS was too close to this mount and I could see some glow.
  4. Centered the beam on all optics in the WFS path and then the WFS DC.
  5. Centered beam on LSC RFPD.

The reflected spots from the PD are not hitting the dump correctly. WE need to machine a shorter post to lower the dump by ~1 cm to catch the beams.

  9517   Fri Jan 3 15:19:39 2014 ranaSummaryPSLPSL pointing monitoring

 This is a 10-minute trend of the last 60 days of the pointing of the PSL beam.

The main fluctuation seems to be at the ~30 day time scale (not 24 hour) and its all in the vertical direction; the horizontal drift is ~10x less (as long as we believe there is no calibration error).

So what's causing all of this vertical shift? And why is there not just as much horizontal??

  9518   Fri Jan 3 18:21:45 2014 ranaSummaryPSLPSL pointing monitoring

 

 I went to the PSL table to re-align the input pointing to the IMC. After trying to optimize the pointing into the PMC and not succeeding I also then touched the wrong mirror and messed up our IOO QPD reference pointing.

The IMC is locking again, but I'll have to fix the pointing on Monday.

  9519   Mon Jan 6 16:30:31 2014 JenneSummaryPSLPSL pointing monitoring

I'm not sure which pointing Rana wanted to fix today, but here's a measurement of the MC spots.  They actually look pretty good.  There is some room for improvement, but not a lot, so I'm leaving it alone for now, while I play with other things in the IFO.

spot positions in mm (MC1,2,3 pit MC1,2,3 yaw):
[0.63368182839757914, 1.3004245778952557, 0.33621668795755993, -1.5585578137597658, -3.1344594013487286, -1.0533063060089816]

MCspots_6Jan2014.png

  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 

 

  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.

  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.

  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.
  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?

  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.

  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).

  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.

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