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ID Date Author Type Categoryup Subject
  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

 

 

  1951   Wed Aug 26 16:11:41 2009 AlbertoUpdatePSLreference cavity temp box temporarly out of order

It turned out that half an hour was too long. In less than that the reference cavity temperature passed the critical point when the temperature controller (located just below the ref cav power supply in the same rack) disables the input power to the reference cavity power supply.

The controller's display in the front shows two numbers. The first goes with the temperature of the reference cavity; the second is a threshold set for the first number. The power supply gets enabled only when the first number comes under the threshold value.

Now the cavity is cooling down and it will take about another hour for its temperature to be low enough and for the heater power supply to be powered.

  1952   Wed Aug 26 16:31:34 2009 steveUpdatePSLreference cavity temp box temporarly out of order

Quote:

It turned out that half an hour was too long. In less than that the reference cavity temperature passed the critical point when the temperature controller (located just below the ref cav power supply in the same rack) disables the input power to the reference cavity power supply.

The controller's display in the front shows two numbers. The first goes with the temperature of the reference cavity; the second is a threshold set for the first number. The power supply gets enabled only when the first number comes under the threshold value.

Now the cavity is cooling down and it will take about another hour for its temperature to be low enough and for the heater power supply to be powered.

 The cavity temp cooled below SP2 set point 0.1  The Minco SP1 (present temp in Volts) now reading -0.037 so DC power supply was turned on and set to 12V 1A  

 

 

  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.

  1954   Wed Aug 26 19:58:14 2009 Rana, AlbertoUpdatePSLReference Cavity Temperature Control: MINCO PID removed

Summary: This afternoon we managed to get the temperature control of the reference cavity working again.

We bypassed the MINCO PID by connecting the temperature box error signal directly into EPICS.

We couldn't configure the PID so that it worked with the modified temperature box so we decided to just avoid using it.

Now the temperature control is done by a software servo by using the channel C1:PSL-FSS_MINCOMEAS as error signal and driving C1:PSL-FSS_TIDALSET (which we have clip-doodle wired directly to the heater input).

 

We 'successfully' used ezcaservo to stabilize the temperature:

ezcaservo -r C1:PSL-FSS_MINCOMEAS -s 26.6 -g -0.00003 C1:PSL-FSS_TIDALSET

 

We also recalibrated the channels:

C1:PSL-FSS_RMTEMP

C1:PSL-FSS_RCTEMP

C1:PSL-FSS_MINCOMEAS

with Peter King on the phone by using ezcawrite (EGUF and EGUL) but we didn't change the database yet. So please do not reboot the PSL computer until we update the database.

 

More details will follow.

Attachment 1: rc.png
rc.png
  1956   Thu Aug 27 13:42:08 2009 ranaSummaryPSLReference Cavity Temperature Control: psl.db changes

I made the changes to the psl.db to handle the new Temperature box hardware. The calibrations (EGUF/EGUL) are just copied directly from the LHO .db file (I have rsync'd their entire target area to here).

allegra:c1psl>diff psl.db~ psl.db
341,353d340
< grecord(ai,"C1:PSL-FSS_TIDALOUT")
< {
<       field(DESC,"TIDALOUT- drive to the reference cavity heater")
<       field(DISV,"1")
<         field(SCAN,".5 second")
<       field(DTYP,"VMIVME-3113")
<       field(INP,"#C0 S28 @")
<       field(EGUF,"10")
<       field(EGUL,"-10")
<       field(EGU,"volts")
<       field(LOPR,"-10")
<       field(AOFF,"0")
< }
493,494c480,481
<         field(EGUF,"285.675")
<         field(EGUL,"-214.325")
---
>         field(EGUF,"67.02")
>         field(EGUL,"7.96")
508,509c495,496
<         field(EGUF,"726.85")
<         field(EGUL,"-1273.15")
---
>         field(EGUF,"75.57")
>         field(EGUL,"12.31")
531,532c518,519
<         field(EGUF,"726.85")
<         field(EGUL,"-1273.15")
---
>         field(EGUF,"75.57")
>         field(EGUL,"12.31")
605,617d591
< grecord(ai,"C1:PSL-FSS_TIDALINPUT")
< {
<       field(DESC,"TIDALINPUT- tidal actuator input")
<       field(DISV,"1")
<         field(SCAN,".5 second")
<       field(DTYP,"VMIVME-3123")
<       field(INP,"#C0 S3 @")
<       field(EGUF,"10")
<       field(EGUL,"-10")
<       field(EGU,"volts")
<       field(LOPR,"-10")
<       field(AOFF,"0")
< }
1130a1105,1130
> grecord(ai,"C1:PSL-FSS_TIDALINPUT")
> {
>       field(DESC,"TIDALINPUT- tidal actuator input")
>       field(DISV,"1")
>         field(SCAN,".5 second")
>       field(DTYP,"VMIVME-3123")
>       field(INP,"#C0 S3 @")
>       field(EGUF,"10")
>       field(EGUL,"-10")
>       field(EGU,"volts")
>       field(LOPR,"-10")
>       field(AOFF,"0")
> }
> grecord(ai,"C1:PSL-FSS_TIDALOUT")
> {
>       field(DESC,"TIDALOUT- drive to the reference cavity heater")
>       field(DISV,"1")
>         field(SCAN,".5 second")
>       field(DTYP,"VMIVME-3113")
>       field(INP,"#C0 S28 @")
>       field(EGUF,"10")
>       field(EGUL,"-10")
>       field(EGU,"volts")
>       field(LOPR,"-10")
>       field(AOFF,"0")
> }
1143,1144c1143,1144
<         field(HOPR,"0.010")
<         field(LOPR,"-0.010")
---
>         field(HOPR,"2")
>         field(LOPR,"0")

  1957   Thu Aug 27 14:00:33 2009 ranaUpdatePSLRC thermal servo impulse response

I stepped the TIDALSET and looked at what happened. Loop was closed with the very low gain.

The RED guy tells us the step/impulse response of the RC can to a step in the heater voltage.

The GREY SLOWDC tells us how much the actual glass spacer of the reference cavity lags the outside can temperature.

Since MINCOMEAS is our error signal, I have upped his SCAN period from 0.5 to 0.1 seconds in the database and reduced its SMOO from 0.9 to 0.0. I've also copied over the Fricke SLOW code and started making a perl PID loop for the reference cavity.

Attachment 1: Untitled.png
Untitled.png
  1968   Mon Sep 7 20:05:18 2009 ranaUpdatePSLRCTEMP v. RMTEMP

Since ~Aug. 27, the reference cavity has been running with no thermal control. This is not really a problem at the 40m; a 1 deg change of the glass cavity

will produce a 5 x 10-7 strain in the arm cavity. That's around 20 microns of length change.

This open loop time gave us the opportunity to see how good our cavity's vacuum can insulation is.

 

rct.pngrct2.png

The first plot below shows the RCTEMP sensors and the RMTEMP sensor. RMTEMP is screwed down to the table close to the can and RCTEMP is on the can, underneath the insulation. I have added a 15 deg offset to RMTEMP so that it would line up with RCTEMP and allow us to see, by eye, what's happening.

There's not enough data here to get a good TF estimate, but if we treat the room temperature as a single frequency (1 / 24 hours) sine wave source, then we can measure the delay and treat it as a phase shift. There's a ~3 hour delay between the RMTEMP and RCTEMP. If the foam acts like a single pole low pass filter, then the phase delay of (3/24)*360 = 45 deg implies a pole at a ~3 hour period. I am not so sure that this is a good foam model, however.

The colorful plot is a scatter plot of RCTEMP v. RMTEMP. The color denotes the time axis - it starts out blue and then becomes red after ten days.

  1970   Mon Sep 7 23:35:03 2009 ranaUpdatePSLRC thermal servo: PID script modified, database + screen added

I have added the records for the RC thermal PID servo into the psl/slowpid.db file which also holds the records for the SLOW servo that uses the NPRO-SLOW to minimize the NPRO-FAST. This new database will take effect upon the next PSL boot.

The perl script which runs the servo is scripts/PSL/FSS/RCthermalPID.pl. Right now it is using hard-coded PID parameters - I will modify it to use the on-screen values after we reboot c1psl.

The new screen C1PSL_FSS_RCPID.adl, the script, and the .db have been added to the SVN.

I have got some preliminary PID parameters which seem to be pretty good: The RCTEMP recovers in ~10 minutes from a 1 deg temperature step and the closed loop system is underdamped with a Q of ~1-2.

I'm leaving it running on op340m for now - if it goes crazy feel free to do a 'pkill RCthermalPID.pl'.

Attachment 1: Untitled.png
Untitled.png
  1972   Tue Sep 8 12:26:16 2009 AlbertoUpdatePSLConnection of the RC heater's power supply replaced

I have replaced the temporary clamps that were connecting the RC heater to its power supply with a new permanent connection.

In the IY1 rack, I connected the control signal of the RC PID temperature servo - C1:PSL-FSS_TIDALSET - to the input of the RC heater's power supply.

The signal comes from a DAC in the same rack, through a pair of wires connected to the J9-4116*3-P3 cross-connector (FLKM). I joined the pair to the wires of the BNC cable coming from the power supply, by twisting and screwing them into two available clamps of the breakout FKLM in the IY1 rack - the same connected to the ribbon cable from RC Tmeperature box.

Instead of opening the BNC cable coming from the power supply, I thought it was a cleaner and more robust solution to use a BNC-to-crocodile clamp from which I had cut the clamps off.

During the transition process, I connected the power supply BNC input to a a voltage source that I set at the same voltage of the control signal before I disconnected it (~1.145V).

I monitored the temperature signals and it looked like the RC Temperature wasn't significantly affected by the operation.

  1976   Tue Sep 8 19:30:33 2009 ranaUpdatePSLc1psl rebooted for new RCPID database settings

The RC thermal PID is now controllable from its own MEDM screen which is reachable from the FSS screen. The slowpid.db and psl.db have been modified to add these records and all seems to be working fine.

Also, I've attached the c1psl startup output that we got on the terminal. This is just for posterity.

I'm also done tuning the PID for now. Using Kp = -1.0, Ki = -0.01, and Kd = 0, the can servo now has a time constant of ~10 minutes and good damping as can be seen in the StripTool snap below. These values are also now in the saverestore.req so hopefully its fully commissioned.

I bet that its much better now than the MINCO at holding against the 24 hour cycle and can nicely handle impulses (like when Steve scans the table). Lets revisit this in a week to see if it requires more tuning.

Attachment 1: c1psl-term-dump.txt.gz
Attachment 2: C1PSL_FSS_RCPID.png
C1PSL_FSS_RCPID.png
Attachment 3: Picture_1.png
Picture_1.png
  1978   Tue Sep 8 20:15:33 2009 rana, jenneSummaryPSLRC temperature servo: Heater Voltage noise

We measured the voltage noise of the heater used to control the RC can temperature. It is large.

TEK00074.PNG

The above scope trace shows the voltage directly on the monitor outputs of the heater power supply. The steps are from the voltage resolution of the 4116 DAC.

We also measured the voltage noise on the monitor plugs on the front panel. If these are a true representation of the voltage noise which supplies the heater jacket, then we can use it to estimate the temperature fluctuations of the can. Using the spectrum of temperature fluctuations, we can estimate the actual length changes of the reference cavity.

I used the new fax/scanner/toaster that Steve and Bob both love to scan this HP spectrum analyzer image directly to a USB stick! It can automatically make PDF from a piece of paper.

The pink trace is the analyzer noise with a 50 Ohm term. The blue trace is the heater supply with the servo turned off. With the servo on (as in the scope trace above) the noise is much much larger because of the DAC steps.

Attachment 1: 09080901.PDF
09080901.PDF
  1983   Thu Sep 10 18:25:15 2009 ranaUpdatePSLc1psl rebooted for new RCPID database settings

I added a new database record (C1:PSL-FSS_RCPID_SETPOINT) to allow for changing of the RC setpoint while the loop is on. This will enable us to step the can's temperature and see the result in the NRPO's SLOWDC.

 

  1986   Sat Sep 12 15:40:15 2009 ranaUpdatePSLRC response v. can temperature

I stepped the RC can temperature to see the response in the laser frequency. This gives a true measure of the thermal time constant of the RC. Its ~4 hours.

Since the RCPID screen now has a setpoint field, I can remotely type in 1 deg steps. The NPRO SLOW actuator locks the NPRO to the RC at long time scales and so we can use C1:PSL-FSS_SLOWDC to measure the RC length. By knowing what the step response time constant is, we can estimate the transfer function from can temperature to frequency noise and thereby make a better heater circuit.

 Does the observed temperature shift make any sense? Well, John Miller and I measured the SLOW calibration to be 1054 +/- 30 MHz / V.

We know that the thermal expansion coefficient of fused silica, alpha = 5.5 x 10-7 (dL/L)/deg. So the frequency shift ought to be alpha * c / lambda = 155 MHz / deg.

Instead we see something like 110 MHz / deg. We have to take more data to see if the frequency shift will actually asymptote to the right value or not. If it doesn't, one possibility is that we are seeing the effect of temperature on the reflection phase of the mirror coatings through the dn/dT and the thermal expansion of the dielectric layers. I don't know what these parameters are for the Ta2O5 layers.

A more useful measure of the frequency noise can be gotten by just looking at the derivative in the first 30 minutes of the step, since that short time scale is much more relevant for us. Its 0.04 V / hour / (2 deg) =>  860 (Hz/s)/deg.

In the frequency domain this comes out to be dnu/dT = 860 Hz/deg @ 0.16 Hz or dnu/dT = 137 *(1/f) Hz / deg.

Our goal for the reference cavity frequency noise is 0.01 * (1/f) Hz/rHz. So the temperature noise of the can needs to be < 0.1 mdeg / rHz.

Attachment 1: Picture_2.png
Picture_2.png
Attachment 2: Untitled.pdf
Untitled.pdf
  1991   Fri Sep 18 14:25:00 2009 robOmnistructurePSLwater under the laser chiller

rob, koji, steve

We noticed some water (about a cup) on the floor under the NESLAB chiller today.  We put the chiller up on blocks and took off the side panel for a cursory inspection, but found no obvious leaks.  We'll keep an eye on it.

  1992   Fri Sep 18 16:05:08 2009 JenneOmnistructurePSLwater under the laser chiller

Quote:

rob, koji, steve

We noticed some water (about a cup) on the floor under the NESLAB chiller today.  We put the chiller up on blocks and took off the side panel for a cursory inspection, but found no obvious leaks.  We'll keep an eye on it.

 The culprit has been found:  One of the bottles of chiller water had a tiny leak in it, and apparently the floor is sloped just right to make it look like the water had been coming from under the chiller.  All is well again in the world of chilled water.

  1993   Fri Sep 18 16:26:02 2009 steveSummaryPSLNeslab chiller is OK

Rob found puddles of water very close to the chiller during lunch time. We raised the unit and took the side cover off. All surfaces were dry and the water level in the tub normal.

Later on we discovered that one of the Vons distilled water bottle was leaking. Jenne and I checked for excess amount of condensing water droplets inside the MOPA box.

On the bare,not insulated tubing and valve are loaded with droplets of water. Relative humidity is 44% at 24 C and HEPA filter speed set to 80 V in the enclosure.

 

  1995   Wed Sep 23 19:36:41 2009 ranaUpdatePSLRC temperature performance

This first plot shows the RC temperature channels' performance from 40 days ago, before we disabled the MINCO PID controller. Although RCTEMP is supposed to be the out of loop sensor, what we really care about is the cavity length and so I've plotted the SLOW. To get the SLOW on the same scale, I've multiplied the channel by 10 and then adjusted the offset to get it on the same scale.

 The second plot shows a period after that where there is no temperature control of the can at all. Same gain scaling has been applied to SLOW as above, so that instead of the usual 1 GHz/V this plot shows it in 0.1 GHz/V.

The third plot shows it after the new PID was setup.

Summary: Even though the PID loop has more gain, the true limit to the daily fluctuations in the cavity temperature and the laser frequency are due to the in-loop sensors measuring the wrong thing. i.e. the out-of-loop temperature is too different from the in-loop sensor. This can possibly be cured with better foam and better placement of the temperature sensors. Its possible that we're now just limited by the temperature gradients on the can.

Attachment 1: Untitled.png
Untitled.png
Attachment 2: Untitled.png
Untitled.png
Attachment 3: e.png
e.png
  2008   Sun Sep 27 14:45:45 2009 KojiUpdatePSLSLOWscan result

I ran (script dir)/PSL/FSS/SLOWscan on op440m from 11:30 to 12:30 on 27th. Although Rana and later I myself set "timed bombs" for the scan, they did not work as they have probably been ran on Linux. After the scan I relocked PMC, FSS, and MZ . MC locked automatically.

Observation:

1. To keep away from the mode hop, FSS_SLOWDC is to be at around 0. The values -5 ~ -6 is the place for the power, which is my preference for now. BTW, the mode hop only appears to the PSL output (=AMPMON) is this normal?

2. The PSL output looks dependent on the NPRO wavelength. The NPRO output and the PSL output tends to be high when the FSS_SLOWDC is low (= LTMP: Laser Crystal Temp is low). Also there is a step at the LTMP where we think the mode hop is present. This may cause the daily PSL output variation which induced by the daily change of the reference cavity length.

My naive speculation is that the NPRO wavelength is too long (= hot side) for the MOPA absorption as the MOPA heads are cooled to 19deg.

3. Scanning of -10 to +10 changes the LTMP from 42-49deg. This is almost 1/10 of the NPRO capability. The manual told us that we should be able to scan the crystal temperature +/-16deg (about 30deg to 60deg).

What I like to try:
a) Change the NPRO temp to more cold side.
b) Change the MOPA head temp to a bit hot side.
c) Tweak the MOPA current (is it difficult?)

Attachment 1: SLOWscan_090927.png
SLOWscan_090927.png
Attachment 2: Pages_from_miser_126_manual.png
Pages_from_miser_126_manual.png
  2009   Sun Sep 27 15:25:58 2009 KojiUpdatePSLSLOWscan result
Oh, AMPMON dependence could be an artifact of the ND filter???
For my case, it should be real dependence on the NPRO wavelength,
as the other PDs like the PMC reflection (PMC_RFPDDC) and the RC reflection (FSS_RFPDDC) show the same dependence.
Attachment 1: power_dependence.png
power_dependence.png
  2010   Sun Sep 27 23:21:14 2009 ranaUpdatePSLSLOWscan result

Quote:

What I like to try:
a) Change the NPRO temp to more cold side.
b) Change the MOPA head temp to a bit hot side.
c) Tweak the MOPA current (is it difficult?)

 I think that the AMPMON ND problem was just that the responsivity changes with angle. So when I aligned it a little we got some few% improvement in the signal which is not a real power increase.

I don't think we can adjust any of the MOPA parameters because the controller is broken, but we can try the NPRO crystal temperature.

  2013   Mon Sep 28 17:39:34 2009 robUpdatePSLproblems

The PSL/IOO combo has not been behaving responsibly recently. 

The first attachment is a 15 day trend of the MZ REFL, ISS INMON, and MC REFL power.  These show two separate problems--recurring MZ flakiness, which may actually be a loose cable somewhere which makes the servo disengage.  Such disengagement is not as obvious with the MZ as it is with other systems, because the MZ is relatively stable on its own.  The second problem is more recent, just starting in the last few days.  The MC is drifting off the fringe, either in alignment, length, or both.  This is unacceptable.

The second attachment is a two-day trend of the MC REFL power.  Last night I carefully put the beam on the center of the MC-WFS quads.  This appears to have lessened the problem, but it has not eliminated it. 

It's probably worth trying to re-measure the MCWFS system to make sure the control matrix is not degenerate. 

Attachment 1: problems.png
problems.png
Attachment 2: problems2.png
problems2.png
  2033   Thu Oct 1 10:23:00 2009 steveUpdatePSLMC2 damping restored again

 The EQ did not change the input beam pointing. All back to normal, except MC2 wachdogs tripped again.

Attachment 1: mc2again.jpg
mc2again.jpg
  2049   Mon Oct 5 09:31:05 2009 AlbertoFrogsPSLPSL laser accidentally turned off

Alberto, Steve,

While I was moving a cart near by the PSL table I pushed the red emergency button that turns off the PSL laser. We had to unlock the button and then power cycle the laser driver to turn the laser back on.

I relocked MZ, FSS, PMC and I'm now waiting for the power to finish ramping up back to the previous value.

  2050   Mon Oct 5 10:41:31 2009 KojiUpdatePSLPSL laser accidentally turned off

The PSL output looks smaller than the incident. Try to FSS Slow actuator adj of -5.6 (nominal), instead of -3.5.

Quote:

Alberto, Steve,

While I was moving a cart near by the PSL table I pushed the red emergency button that turns off the PSL laser. We had to unlock the button and then power cycle the laser driver to turn the laser back on.

I relocked MZ, FSS, PMC and I'm now waiting for the power to finish ramping up back to the previous value.

 

  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?

  2055   Mon Oct 5 19:39:26 2009 KojiUpdatePSLPSL laser accidentally turned off

I set the FSS slow actuator adj to -5.6 at the lunch time. It gave a little help at that time. Now max of the MC Trans is comming back somehow. I hope the MC Trans level is as good as before, if the HEPA is slowed down.

Quote:

The PSL output looks smaller than the incident. Try to FSS Slow actuator adj of -5.6 (nominal), instead of -3.5.

Quote:

Alberto, Steve,

While I was moving a cart near by the PSL table I pushed the red emergency button that turns off the PSL laser. We had to unlock the button and then power cycle the laser driver to turn the laser back on.

I relocked MZ, FSS, PMC and I'm now waiting for the power to finish ramping up back to the previous value.

 

 

  2057   Tue Oct 6 10:09:55 2009 ZachUpdatePSLMore pictures

I'm back to terrorize the PSL table again. The pictures I took yesterday were rubbish--today I'm using a clamp that Steve was nice enough to loan me. I'm starting now, at 10:09 am.

  2083   Mon Oct 12 18:37:55 2009 ZachUpdatePSLInventory

--Apologies for the late post--

I was at the PSL table taking an inventory of the components for a while after Koji, Steve, and Kiwamu were there. I set the HEPAs back to 20% when I left (assuming that they were turned up when the compartment was opened).

  2088   Mon Oct 12 22:15:15 2009 ranaConfigurationPSLStray beam blocking

You can remove the RFAM measuring setup. Once we upgrade, we will no longer have a MZ or the related problems.

  2089   Tue Oct 13 10:31:11 2009 ZachUpdatePSLone more time

I am at the PSL table taking what is hopefully the last set of pictures for the diagram. Woohoo.

  2090   Tue Oct 13 10:50:58 2009 ZachUpdatePSLone more time

Quote:

I am at the PSL table taking what is hopefully the last set of pictures for the diagram. Woohoo.

 I'm out, HEPAs are back at 20%.

  2098   Thu Oct 15 12:35:09 2009 ZachUpdatePSLinventory

I'm at the PSL table taking inventory of the elements I don't have down yet.

  2099   Thu Oct 15 12:57:23 2009 ZachUpdatePSLinventory

Quote:

I'm at the PSL table taking inventory of the elements I don't have down yet.

 OK, I'm out--hopefully for good. HEPAs back at 20%.

  2142   Mon Oct 26 15:40:01 2009 steveUpdatePSLlaser power is down

The laser power is down 5-6%

Attachment 1: laserpowerdown.jpg
laserpowerdown.jpg
  2147   Mon Oct 26 23:14:08 2009 KojiUpdatePSLlaser power is down

I adjusted the steerings to the PMC and gained 7%. Now the MC_TRANS 7.0 has been recovered.

Actually I need another 7% to get MC_TRANS 7.5.
But I couldn't find how I can recover 126MOPA-AMPMON to 2.8ish.

Quote:

The laser power is down 5-6%

 

Attachment 1: PSL091026.png
PSL091026.png
  2151   Tue Oct 27 18:01:49 2009 robUpdatePSLhmmm

A 30-day trend of the PCDRIVE from the FSS.

Attachment 1: pcdrive_trend.png
pcdrive_trend.png
  2155   Wed Oct 28 09:12:18 2009 steveUpdatePSLPMC power on the rise?

The PMC power is seems to be on the rise, ( MOPA_AMPMON is dropping ?) but I do not think it is real. We have Santa Anna wind condition, when the relative humidity drops and  ......

There is an other funky think. The room temp became rock solid. The PSL HEPAs running at 20% and IFO-room ACs are also in normal operational mode.

Attachment 1: pmcprising.jpg
pmcprising.jpg
  2158   Thu Oct 29 13:48:32 2009 KojiUpdatePSLNPRO LTMP lowered 9.5deg

13:00 Found MC TRANS less than 7.
13:50 Go into the PSL table.
14:20 Work done. Now I am running SLOWscan script.
15:10 SLOWscan finished. It was not satisfactory. I go into the table again.
15:15 Running SLOWscan again.
16:00 SLOWscan done. Lock PMC. Adjust NPRO current so as to maximize PMC TRANS.
16:10 Lock RC, PMC, MZ, MC. Align PMC / MZ on the table. Align MC WFS beams on the QPDs.
16:30 Work done.

New FSS-SLOWDC nominal is -4.0

Now MC TRANS is 7.9. This is +12% increase. ENJOY!
HEPA is on at 90%. Light is off.

---------

NPRO TEMP trimmer adjustment
o PSL NPRO TEMP trimmer at the back of the laser head was turned 6.5 times in CW.
o It reduced NPRO crystal temp by 9.5deg. (43.5deg -> 34.0deg for FSS_SLOWDC -5.5)

To revert the previous setting, refer to the former measurement
c.f. http://nodus.ligo.caltech.edu:8080/40m/2008

NPRO Thermal scan
o 2 scans are performed.
o I selected the colder side of the second scan. i.e. SLOWDC=-4.0

NPRO Current adjustment
o Tweaked C1:PSL-126MOPA_126CURADJ while looking at PMC TRANS.
o CURADJ was changed from -2.25 to -1.9. This corresponds to change of C1:PSL-126MOPA_CURMON from 2.503A to 2.547A.

Attachment 1: 091028_PSL.png
091028_PSL.png
  2161   Thu Oct 29 20:21:14 2009 KojiUpdatePSLNPRO LTMP lowered 9.5deg

Here is the plots for the powers. MC TRANS is still rising.

What I noticed was that C1:PSL-FSS_PCDRIVE nolonger hit the yellow alert.
The mean reduced from 0.4 to 0.3. This is good, at least for now.

Attachment 1: PSL_MC.png
PSL_MC.png
  2165   Fri Oct 30 10:52:56 2009 JenneUpdatePSLHEPAs

Zach found the HEPA switch on the PSL table OFF.  He turned them on.

  2169   Mon Nov 2 13:34:36 2009 kiwamuConfigurationPSLremoved multiply resonant EOM

I removed the multiply resonant EOM that has been set by a SURF student from PSL table.

I will use it for checking the resonant circuit.

  2236   Wed Nov 11 12:29:44 2009 AlbertoFrogsPSLMC Locked on the wrong mode?

This morning, after Steve pointed out that the readout RFAMPD_DC was zero, I thought of realigning the beam on the photodiode. Maybe I touched the lens or the beam splitter that send the beam on the diode when I installed an other beam splitter to make the measurement of the calibration between two ThorLabs PDA255 photodiodes.

After aligning the beam on the RFAMPD, the voltage of the DC readout was lower than it used to be (C1:IOO-RFAMPD_DC ~ 0.4 now vs. 4 as it was on November 4th).

I maximized the DC readout but the problem seems to be that the beam spot is not a round TEM00. In particular the spot looks like that of a TEM10 mode.

Since we're looking at the MC transmitted beam, is it possible that the MC is locked on the wrong mode?

Check out the attached picture.

Attachment 1: PB110184-1.JPG
PB110184-1.JPG
  2249   Thu Nov 12 10:45:02 2009 AlbertoUpdatePSLAbandoned Frequency Generator

This morning I found a frequency generator connected to something on the PSL table sitting on the blue step next to the sliding doors.

Is anyone using it? Has it been forgotten there? If that's the case, can the interested person please take care of removing it?

  2251   Thu Nov 12 11:19:10 2009 KojiUpdatePSLAbandoned Frequency Generator

Last night there was an activity for a calibratuon work, which I helped. I can take care of the FG.

Quote:

This morning I found a frequency generator connected to something on the PSL table sitting on the blue step next to the sliding doors.

Is anyone using it? Has it been forgotten there? If that's the case, can the interested person please take care of removing it?

 

  2256   Thu Nov 12 16:13:05 2009 AlbertoUpdatePSLMC Trans Offset

On Rana's suggestion I checked the MC transmission QPD (C1:IOO-MC_TRANS_SUM). I found that the readout is almost zero when the MC is unlocked.

I unlocked the Mode Cleaner turning off the LSC control and disabling the autolocker. The QPD reads 0.014. It seems that there is no offset.

I also checked with the IR card around the photodetector and I didn't see any stray beam.

  2258   Thu Nov 12 17:15:43 2009 KojiUpdatePSLMC Trans Offset

OK. I have been keeping my eyes on the MC transmission. In deed, the MC trans has been well kept at around 7.7 since the last PSL work.
Even it was over the 8 today!

Quote:

On Rana's suggestion I checked the MC transmission QPD (C1:IOO-MC_TRANS_SUM). I found that the readout is almost zero when the MC is unlocked.

I unlocked the Mode Cleaner turning off the LSC control and disabling the autolocker. The QPD reads 0.014. It seems that there is no offset.

I also checked with the IR card around the photodetector and I didn't see any stray beam.

 

Attachment 1: MC_TRANS.png
MC_TRANS.png
  2260   Thu Nov 12 17:42:04 2009 KojiUpdatePSLMC Trans Offset

PC_DRIVE is also improving after the last PSL work!

Quote:

OK. I have been keeping my eyes on the MC transmission. In deed, the MC trans has been well kept at around 7.7 since the last PSL work.
Even it was over the 8 today!

 

Attachment 1: PC_DRV.png
PC_DRV.png
  2311   Mon Nov 23 00:46:09 2009 rana, robUpdatePSLISS RIN: Its too high by 10x

This plot shows the RIN as measured by the ISS. Its ~2 x 10^-7, whereas its supposed to be more like 3 x 10^-8.

The ISS has DC coupled RIN channels (with a _F suffix) and AC coupled RIN channels (with a _FW suffix). By using a swept sine, Rob determined that the AC coupled channels have an AC coupling pole at ~80 Hz. The attached plot uses this and then has the overall gain adjusted to match with the _F channels below 10 Hz.

The _F channels can be converted directly into RIN by just dividing the spectra by the mean value of the time series. The dark offset of these channels is small and so this only introduces a ~5-10% calibration error.

Question #1: Why is the RIN so bad? According to the MEDM screen, the photocurrent on the MON/SENS PDs is 1.9/1.3 mA. That's sort of low, but should still allow us to get 5x10^-8 in RIN.

Question #2: Does it make an effect on the current DC Readout work? IF so, should we try to fix up the ISS in a temporary way? Since the in-loop and out-of-loop detectors are completely coherent, all of the noise is likely just unsuppressed noise from the laser. We are unable to increase the gain because of the high frequency noise from the NPRO.

 

Let's remember to replace this ISS with a new one that can drive an AOM. Need a volunteer to get us a new ISS.

 

Attachment 1: Untitled.png
Untitled.png
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