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ID Date Author Type Category Subject
10834   Tue Dec 23 13:18:37 2014 manasaUpdateGeneralX end AUX laser fiber setup

 Quote: Since we will not be doing any major locking, I am taking this chance to move things on the X end table and install the fiber coupler. The first steering mirror shown in the earlier elog will be a Y1 (HR mirror) and the second one will be a beam sampler (similar to the one installed at the Y endtable for the fiber setup).  Configuration: Doubler --> Y1 ---> Lens (f=12.5cm) ---> Beam sampler --->Fiber coupler The fiber coupler mount will be installed in the green region to the right of the TRX camera.  This work will involve moving around the TRX camera and the optic that brings the trans image on it. Let me know if this work should not be done tomorrow morning for any reason.

I was working around the X endtable and PSL table today.

1. Y1 mirror, beam sampler and the fiber coupler have been installed.

2. Removed TRX camera temporarily. The camera will be put back on the table once we have the filter for 532nm that can go with it.

3. Removed an old fiber mount that was not being used from the table.

4. Lowered the current for X end NPRO while working and put it back up at 2A before closing.

5. The fibers running from the X end to the PSL table are connected at an FC/APC connector on the PSL table.

6. Found the HEPA left on high (probably from yesterday's work around the PSL table). I have brought it back down and left it that way.

I have not installed the coupling lens as yet owing to the space restrictions - not enough space for footprint of the lens. I have to revisit the telescope design again.

10867   Wed Jan 7 12:15:17 2015 manasaUpdateGeneralNew RF cables

I was working around the PSL table this morning.

1. I have fibers running from the Y end and the PSL table to the Optical Fiber Module for Frequency Offset Locking.

Y+PSL out power is ~200uW. From the transimpedance and responsivity specs of the RFPD (ThorLabs FPD310), we expect ~100uW or -10dBm RF power. I have not hooked up the RF output to a spectrum analyser to confirm this as yet.

2. Also, Steve and I ran RF cables (LMR-195A) from the PSL table to the FC module on the IOO rack.

10873   Wed Jan 7 19:49:09 2015 manasaUpdateGeneralX end space issues

I have attached a photo of the ETMX table. The path of the 1064nm light rejected after the doubler and the green light are indicated for reference.

The fiber mount can only be mounted in the green space shown in the picture.

Calculating lens solutions for coupling the 1064nm light rejected after the doubler into the fiber, a lens of f=12.5cm should be placed at z=15.31cm (measured from the waist in the doubler crystal) gives the best ~80% coupling. This falls in the blue region where there is not enough space to mount a lens

The region marked in orange has enough room for a lens; but the lens solutions give a coupling <10% which means there will be light scattering everywhere.

10883   Fri Jan 9 14:01:17 2015 manasaUpdateGeneralAUX Y + PSL beat note at 1064nm

I worked around the PSL table today.

The Y+PSL output from the optical fiber module for FOL was fed to the input of the Thorlabs FPD310
200uW of incident light on the RFPD gave an RF signal of -70dBm as measured on a spectrum analyzer.

I swapped the beam splitter along the PSL path so that the incident power on the RFPD is ~1.5mW (Maximum incident power that the PD can tolerate is ~2mW).
This RF signal generated was - 43dBm which is still small for the input to the frequency counter module.

I checked this with a function generator and found that the frequency counter requires around -25 to -30 dBm at the input.

I plan to use the Minicircuits ZFL-1000ln that is on the IOO rack but not being used (This was used for green beatnote amplification but is not required/used anymore) to amplify the RF signal to the frequency counter.
If anyone has any objections to using this amplifier for the frequency counter, let me know.

10884   Fri Jan 9 14:13:02 2015 manasaUpdateGeneralALS noise at ~30Hz

Before starting to move things around the PSL table, I measured the ALS out of loop noise for reference. The noise spectrum showed excess noise around 30Hz.  The traces in blue were taken before I went in and those in red were taken after my work.

I also looked at the power spectrum of LSC-TRY_OUT to see if the noise is from the IR lock itself and there was nothing suspicious with it.

Since the green transmission was 50% lower than the usual, I touched the steering mirrors for green at the Y end table to get a better transmission and beat signal. The noise still hasn't disappeared.

I am not sure if this could be from our neigbors who have been running rock experiments since morning. We should check back to see if this noise disappears once they shut down.

DTT xml files are available in directory /users/manasa/data/150109/

Attachment 1: ALSYoutLoop.png
Attachment 2: LSC_TRY.png
10893   Tue Jan 13 10:28:02 2015 manasaUpdateGeneralAUX Y + PSL beat note at 1064nm
 Quote: I plan to use the Minicircuits ZFL-1000ln that is on the IOO rack but not being used (This was used for green beatnote amplification but is not required/used anymore) to amplify the RF signal to the frequency counter. If anyone has any objections to using this amplifier for the frequency counter, let me know.

The above mentioned amplifier has been used to amplify the input to the frequency counter. The frequency counter is now getting an input that it can read.

I have done an edit to the ALS medm screen and the PSL and AUX Y laser beat frequency is now readable.

10895   Tue Jan 13 14:01:20 2015 manasaUpdateGeneralAUX Y + PSL beat note at 1064nm: needs work
 Quote: I'm super excited about this new frequency readback, but I'm not sure that it's reliable yet.  Without touching any settings, the readback is currently saying 78.6MHz, and is changing slightly (as is the FSS Slow Temp), so something is working.  However, the beatnote as measured on the spectrum analyzer is 158.2MHz.  So, either the calibration or the tracking or something isn't quite finished being tuned yet. It's going to be super awesome when we have this though!!

As Jenne pointed out, this is still not fully tuned.

For example, I found today that the frequency counter requires more power at the input >= -20dBm to measure frequency inputs < 40 MHz. Since the RFPD gives ~ -40dBm at its output, the ~20dB gain amplifier will not be enough to measure low frequencies in case the beat power at the PD drops (which is very much possible when the alignment drifts or things move around on the PSL table).  So I am shopping for an RF amplifier with higher gain to replace the current one. In the meantime, I will test the PID loop for set point frequency > 40MHz.

I have also observed the frequency difference between the measured frequencies on FC and the spectrum analyzer. I am not sure where this comes from as yet.

At this point, the FC readout is only reliable enough to find a beatnote that is lost on the spectrum analyzer.

10918   Sat Jan 17 15:07:28 2015 manasaUpdateGeneralBeat note frequency discrepancy

I was around the PSL table and the X end table today.

X end table:

I was at the X end table making some distance measurements for the telescope to the fiber coupler. I have NOT moved anything as yet.

PSL table:

I wanted to get some data to look at the beat note frequency discrepancy between the green and IR.

I tried making measurements using the spectrum analyzer at the PSL table but the MC was getting unlocked quite often with PSL enclosure open and HEPA on high.

So I switched off the power supplies to the RFPDs (3 of them) on the PSL table and disconnected the Xmon input to the adder (at the IOO rack) which brings the green beat note signals to the conrol room. I connected the fiber RFPD output to the adder and took a bunch of measurements of the green and IR beat notes from the spectrum analyzer in the control room. I have NOT undone this setup assuming there are no locking plans for tonight and I will come back tomorrow.

If anyone is planning to do some locking in the meantime, you can undo the connections keeping in mind to turn off the power to the RFPDs before you do so.

P.S. I walked in this morning to PSL FSS slow actuator at 0.89 and brought it down to zero before making measurements.
I also touched the steering mirrors that are part of the Y green beat note alignment while looking at the amplitude of the RF signal on the spectrum analyzer.

10919   Mon Jan 19 11:03:32 2015 manasaUpdateGeneralRF connections to adder

RF connections to the beat note adder on the IOO rack have been undone and it should be good to proceed with any locking attempts.

 Quote: I was around the PSL table and the X end table today. X end table: I was at the X end table making some distance measurements for the telescope to the fiber coupler. I have NOT moved anything as yet. PSL table: I wanted to get some data to look at the beat note frequency discrepancy between the green and IR.  I tried making measurements using the spectrum analyzer at the PSL table but the MC was getting unlocked quite often with PSL enclosure open and HEPA on high.  So I switched off the power supplies to the RFPDs (3 of them) on the PSL table and disconnected the Xmon input to the adder (at the IOO rack) which brings the green beat note signals to the conrol room. I connected the fiber RFPD output to the adder and took a bunch of measurements of the green and IR beat notes from the spectrum analyzer in the control room. I have NOT undone this setup assuming there are no locking plans for tonight and I will come back tomorrow.  If anyone is planning to do some locking in the meantime, you can undo the connections keeping in mind to turn off the power to the RFPDs before you do so. P.S. I walked in this morning to PSL FSS slow actuator at 0.89 and brought it down to zero before making measurements. I also touched the steering mirrors that are part of the Y green beat note alignment while looking at the amplitude of the RF signal on the spectrum analyzer.

10954   Thu Jan 29 09:50:47 2015 manasaUpdateElectronicsIOO rack amplifier panel

The RF amplifier panel on the IOO rack (Attachment 1) will be used to also hold the RF amplfiers for the frequency counters. The amplifiers mounted on it right now are getting +15 (orange wire) and GND (black wire) from the rack power supply (Attachment 2).

Proposed plan to install RF amplifiers:

1. Disconnect the D sub connector that powers the amplifiers and pull out the panel. The rack power supplies will NOT be shut down for this.

2. Mount the RF amplifiers with bypass capacitors. There will be 4 amplifiers ZFL-500LN mounted on the same panel (2 for each frequency counter).

3. While putting back the panel on the IOO rack, we will need to shut down the +15V and -15V sources to connect the amplifiers to the rack power supply.

I will do this over this weekend so that we dont lose any locking time. If anybody has any concerns, let me know

Attachment 1: panel_front.jpg
Attachment 2: panel_back.jpg
10955   Thu Jan 29 10:14:21 2015 manasaUpdateGeneralX end space issues

It is certain that we have space issues at the X end that has been preventing us from sticking in a lens to couple light into the fiber.

The only way out is to install a platform on the table where we can mount the lens. I have attached the a photo of how things look like at the X end (attachment 1) and also a drawing of the platform that which can hold the lens (attachment 2). Additional support to the raised platform will be added depending on how much space we can clear up on the table by moving the clamping forks of the doubler.
Steve and I have been able to gather parts that can be put together into something similar to what is shown in the drawing.

Proposed modifications to the X end table:

1. The side panels of the table enclosure will come out while putting in the new platform.

2. The clamping forks for the doubling crystal will be moved.

Let me know of any concerns about the proposed solution.

Attachment 1: photo.png
Attachment 2: drawing.png
10956   Thu Jan 29 11:59:48 2015 manasaUpdateGeneralBeat note frequency discrepancy

Below is the set of plots comparing measurements for the green and IR beat notes frequencies. The measurements were made on the spectrum analyzer at the same time. So I have not taken measurement error into account.
From the plots, the discrepancy is not very large.

Attachment 1:
Shows the two sets of measurements scaterred along y=x.

Attachment 2:
Since plot 1 shows the points tightly scattered to y=x, I plotted the difference between the two measurements against their mean to blow out the deviations.

I will do the same comparison using the frequency counter readout once we have RF amplifiers installed.

Attachment 1: Freq_compare1.png
Attachment 2: Freq_compare2.png
10957   Thu Jan 29 16:14:10 2015 manasaUpdateGeneralUpdated to do list for FOL

Since there will be some work that supposedly will involve moving stuff on the table and racks; here is the updated to-do list for FOL.

10958   Thu Jan 29 17:20:58 2015 manasaConfigurationIOOX Trans Table less crazy but not enough yet

[Koji, Manasa]

We cleared up some optics and optomechanics at the X end table that are not being used and moved them to the SP table. [Ed by KA: They seemed to be leftover of the other projects. I blame them]

10961   Fri Jan 30 11:37:20 2015 manasaFrogsTreasureSP table madness ends

SP table has been a mess because Q and I had let our SURF leave without cleaning up.

I cleaned up the SP table, put things back where they belong and did some sorting. I will put back the optomechanics where they belong sometime later.

For now, check out the SP table next time you are looking for a Y1  or lens or BS.

10964   Mon Feb 2 16:58:56 2015 manasaUpdateGeneralRF amplifier for ALS

Today I was around the IOO rack.

I shutdown the power to the beat PDs on the PSL table and disconnected the D sub 3w3 connector that was powering the RF amplifier panel on the IOO rack.

I moved the RF amplifier from the panel to a box that can go on the rack. The box will also hold the RF amplifiers that will be used for FOL. I have not completed putting in all the amplifiers. But the RF amplifier for ALS is in place and the box has been installed on the IOO rack for locking tonight. The power supply to the green beat PDs has been switched ON.

I took the out of loop noise measurements for ALS X and Y and the attachment is the screenshot of it (X and Y have rms of ~300Hz and ~400Hz).

I had to touch the Y end steering mirrors for green to get maximum GTRY before making thes measurments.

Attachment 1: ALSXY_outLoop.png
10970   Tue Feb 3 16:43:48 2015 manasaUpdateGeneralRF amplifier for ALS

I pulled out the RF amplifier box from the IOO rack again and added the new RF amplifiers for FOL.

I replaced one of the decoupling capacitors of the ALS beat note RF amplifier ; the poloproylene capacitor with a ceramic capacitor (0.1uF) .

After putting back the box, I confirmed that we had a beat note. I did not get a chance to measure the ALS noise after putting back the box because the IFO was already occupied.

I will post a detailed elog of the components in the RF amplifier box once I am done with it (hopefully tomorrow)!

10977   Wed Feb 4 21:05:24 2015 manasaUpdateGeneralRF amplifier for ALS

The components of the RF amplifier box are in place. The RF amplifier box has been mounted on the IOO rack and the front panel connections have been labeled. Attached is the photo of how things look in the inside for future reference.

Sometime in the next few days the box will be pulled out to replace the panel mount SMA barrels in the front with insulated ones.

Attachment 1: RFampBox.png
10978   Wed Feb 4 21:09:43 2015 manasaUpdateGeneralX endtable work scheduled tomorrow

The X end fiber setup will be put together tomorrow morning. Let me know if there are any concerns.

 Quote: It is certain that we have space issues at the X end that has been preventing us from sticking in a lens to couple light into the fiber.  The only way out is to install a platform on the table where we can mount the lens. I have attached the a photo of how things look like at the X end (attachment 1) and also a drawing of the platform that which can hold the lens (attachment 2). Additional support to the raised platform will be added depending on how much space we can clear up on the table by moving the clamping forks of the doubler. Steve and I have been able to gather parts that can be put together into something similar to what is shown in the drawing.  Proposed modifications to the X end table: 1. The side panels of the table enclosure will come out while putting in the new platform. 2. The clamping forks for the doubling crystal will be moved. Let me know of any concerns about the proposed solution.

10981   Thu Feb 5 15:21:25 2015 manasaUpdateGeneralX endtable work

[EricG, Manasa]

We were at the X end today trying to couple AUX X light into the fiber.

The proposed plan still did not give a good beampath. The last steering mirror before the fiber coupler was sticking out of the table enclosure. I tried a few other options and the maximum coupling that I could get was ~10%

I am working on plan C now; which would be to use fixed mount mirrors and steer the beam to the space created by Koji near the IR trans path and use a set of lenses instead of a single lens. I will elog more details after some modematching calculations.

We moved one of the clamps for the doubling crystal to make space. Also, the NPRO current was reduced during this work.

I reset things to how they were before I touched the table. I ensured that the green power was still the same (~3mW) after the doubler and that it could lock to the arm in TEM00.

10985   Fri Feb 6 18:06:18 2015 manasaUpdateGeneralFiber Optic module for FOL

I pulled out the Fiber Optic Module for FOL from the rack inside the PSL table enclosure and modified it. The beat PDs were moved into the box to avoid breaking the fiber pigtail input to the PD.

The box has 3 input FC/APC connectors (PSL and AUX lasers) and 2 output FC/APC connectors (10% of the beatnote for the AUX lasers).

Attachment shows what is inside the box. The box will again go back on the rack inside the PSL enclosure.

Attachment 1: FOLfiberModule.png
10995   Tue Feb 10 13:48:58 2015 manasaUpdateLSCProbable cause for headaches last night

I found the PSL enclosure open (about a feet wide) on the north side this morning. I am assuming that whoever did the X beatnote alignment last night forgot to close the door to the enclosure before locking attempts

 Quote: Unfortunately, we only had one good CARM offset reduction to powers of about 25, but then my QPD loop blew it. We spent the vast majority of the night dealing with headaches and annoyances.  Things that were a pain: If TRX is showing large excursions after finding resonance, there is no hope. These translate into large impulses while reducing the CARM offset, which the PRMI has no chance of handling. The first time aligning the green beat did not help this. For some reason, the second time did, though the beatnote amplitude wasn't increased noticibly.  NOTICE: We should re-align the X green beatnote every night, after a solid ASS run, before any serious locking work.  Afterwards, phase tracker UGFs (which depend on beatnote amplitude, and thereby frequency) should be frequently checked.  We suffered some amount from ETMX wandering. Not only for realigning between lock attempts, but on one occasion, with CARM held off, GTRX wandered to half its nominal value, leading to a huge effective DARM offset, which made it impossible to lock MICH with any reasonble power in the arms. Other times, simply turning off POX/POY locking, after setting up the beatnotes, was enough to significantly change the alignment.  IMC was mildly tempermental, at its worst refusing to lock for ~20min. One suspicion I have is that when the PMC PZT is nearing its rail, things go bad. The PZT voltage was above 200 when this was happening, after relocking the PMC to ~150, it seems ok. I thing I've also had this problem at PZT voltages of ~50. Something to look out for.  Other stuff: We are excited for the prospect of the FOL system, as chasing the FSS temperature around is no fun.  UGF servo triggering greatly helps the PRMI reacquire if it briefly flashes out, since the multipliers don't run away. This exacerbated the ALS excursion problem.  Using POPDC whitening made it very tough to hold the PRMI. Maybe because we didn't reset the dark offset...?

10996   Tue Feb 10 16:01:21 2015 manasaUpdateGeneralAUX X fiber coupled 72%

Plan C finally worked. We have 1.454mW of AUX X light at the PSL table (2mW incident on the fiber coupler).

Attached is the layout of the telescope.

What I did:

I stuck in Lens 1 (f=200mm) and measured the beam width after the focus of the lens at several points. I fit the data and calculated the beam waist and its position after this lens.

I used the calculated waist and matched it with an appropriate lens and target (fiber coupler) distance. I calculated the maximum coupling efficiency to be 77% for Lens 2 with f=50mm and the fiber coupler placed at 20cm from the waist of Lens1. I was able to obtain 72% coupling after putting the telescope together.

I locked the arms, ran ASS and brought back GTRX to its usual optimum value of ~0.5 counts after closing. We also have the X arm beatnote on the spectrum analyzer.

Notes:

There are still a couple of things to fix. The rejected beam from the beam sampler has to be dumped using a razor blade.

11006   Wed Feb 11 18:44:53 2015 manasaUpdateGeneralOptical fiber module

I have moved the optical fiber module for FOL to the PSL table. It is setup on the optical table right now for testing.

Once tests are done, the box will move to the rack inside the PSL enclosure.

While doing any beat note alignment, please watch out for the loose fibers at the north side of the PSL enclosure until they are sheilded securely (probably tomorrow morning).

11013   Thu Feb 12 12:16:04 2015 manasaUpdateGeneralFiber shielding

[Steve, Manasa]

The fibers around the PSL table were shielded to avoid any tampering.

11014   Thu Feb 12 12:23:21 2015 manasaUpdateGeneralWaking up the PDFR measurement system

[EricG, Manasa]

We woke up the PDFR measurement setup that has been sleeping since summer. We ran a check for the laser module and the multiplexer module. We tried setting things up for measuring frequency response of AS55.
We could not repeat Nichin's measurements because the gpib scripts are outdated and need to be revised.

PDFR diode laser was shutdown after this job.

11065   Wed Feb 25 11:01:05 2015 manasaUpdateComputer Scripts / ProgramsNew screen for FOL PID loop

Created a new medm screen C1ALS_FOL_PID.adl for FOL PID loop control in /medm/als/master/

This is not currently linked to the sitemap screen.

11075   Thu Feb 26 10:56:34 2015 manasaUpdateGeneralRunning cables

[Steve, Manasa]

We ran power cables and sma cables for the FOL fiber module from the PSL table to the IOO rack.

11078   Thu Feb 26 16:37:21 2015 manasaFrogsLSCRIP illegal power supply

No more illegal power supply at the LSC rack

The amplifiers are now being powered by the rack power supply through fuse blocks.

To make new connections, I shutdown the +/-15 V low noise power supplies. They were turned back ON after the work.

Quote:

### Is this your illegally installed HP bench power supply?

If so, or if not but you care about the signal that passes through these amplifiers, I suggest you remove this temporary power supply and wire the power from the rack power supplies through the fuse blocks and possibly use a voltage regulator.

In 24 hours, that power supply will be disconnected and the wires snipped if they are still there.

11079   Thu Feb 26 16:46:37 2015 manasaUpdateGeneralIOO rack power supply

I shutdown the +/-15V and the +/-24V sorensons on the IOO rack to connect the FOL RF PDs to the rack power supply.

They were turned back ON after the work. PMC and MC were relocked.

 Quote: [Steve, Manasa] We ran power cables and sma cables for the FOL fiber module from the PSL table to the IOO rack.

11101   Thu Mar 5 11:18:28 2015 manasaUpdateGeneralRF amplifier box

I pulled out the RF amplifier box from the IOO rack and swapped the amplifiers for FOL beat frequency amplification. The earlier gain of 62dB (ZFL500LN + ZFL500LN) was reduced to 40dB gain (ZFL500LN+ZFL2AD).

I also swapped one of the broken sma cables that was connecting the two amplifiers with a good one. Front ports of the module were relabeled and the box was put back on the rack.

During the course of this work, I had to turn OFF the green BBPDs on the PSL table to protect them and they have been powered up after putting the module back.

 Quote: As Koji found one of the spare channels of the ALS/FOL RF amplifier box nonfunctional yesterday, I pulled it out to fix it. I found that one of the sma cables did not conduct. It was replaced with a new cable from Koji. Also, I rearranged the ports to be consistent across the box, and re-labeled with the gains I observed.  It has been reinstalled, and the Y frequency counter that is using one of the channels shows a steady beat freq. I cannot test the amplitude of the green X beat at this time, as Koji is on the PSL table with the PSL shutter closed, and is using the control room spectrum analyzer. However, the dataviewer trace for the fine_phase_out_Hz looks like free swinging cavity motion, so its probably ok.

11102   Thu Mar 5 12:27:27 2015 manasaUpdateGeneralFOL fiber box on the PSL table

Working around the PSL table

I have put the FOL fiber box on the PSL table. The fibers carrying AUX and PSL light are connected and the RFPDs have been powered up. I can see the beat frequency on the frequency counters; but for some reason Domenica (that brings the frequency counter values on the medm screens) is not visible on the network even after hard reboot of the raspberry pi. I am neither able to ping nor ssh into the machine. I have to pull the module out and add a monitor cable to troubleshoot (my bad I should have left the monitor cable with the raspberry pi in the first place). Anyways, I have handed over the IFO to Q and will play with things again sometime later.

The fiber box on the PSL table is only left there temporariliy till I have things working. It will be stowed on the rack properly later.

In case someone wants the fiber box out of the PSL table, please make sure to power down the RFPDs using the black rocker switches on the side of the box and then disconnect the cables and fibers.

11110   Fri Mar 6 14:29:59 2015 manasaUpdateGeneralFOL troubleshooting

[EricQ, Manasa]

Domenica:
Since Domenica was not picking up an IP address and hence not responding to pings or ssh even after power cycling, I pulled it out from the IOO rack and connected it to a monitor. After a bunch of hit and trials, we figured out that the problem was related to the power adapter of the Rpi discussed here : http://www.raspberrypi.org/forums/viewtopic.php?f=28&t=39055

The power adapter has been swapped and this issue has been resolved. Domenica has been remounted on the IOO rack but left with the top lid off for the timebeing.

RF amplifier box:
The frequency counter was setup to read the beat frequency after amplification of the RFPD signals. The output as seen on the frequency counter screen as well as the epics values was intermittent. Also, locking the arms and changing the end laser frequencies did not change the frequency counter outputs. It looks like the RF amplifier is oscillating (Oscillating frequencies were ~107 MHz and 218 MHz) and the input circuit needs to be modified and the connections need better insulation.

As of now, I have connected the RFPD outputs to the frequency counter sans any amplification and we are able to get a readout of the beat frequency at > 40MHz (Frequency counter requires much higher amplitude signals for frequencies lower than that).

11123   Mon Mar 9 14:43:31 2015 manasaUpdateGeneralFOL troubleshooting

Figuring out the problem with frequency counter readouts:

 RF amplifier box: The frequency counter was setup to read the beat frequency after amplification of the RFPD signals. The output as seen on the frequency counter screen as well as the epics values was intermittent. Also, locking the arms and changing the end laser frequencies did not change the frequency counter outputs. It looks like the RF amplifier is oscillating (Oscillating frequencies were ~107 MHz and 218 MHz) and the input circuit needs to be modified and the connections need better insulation. As of now, I have connected the RFPD outputs to the frequency counter sans any amplification and we are able to get a readout of the beat frequency at > 40MHz (Frequency counter requires much higher amplitude signals for frequencies lower than that).

The frequency counter has 4 ranges of operation:
Range 1 : 1 - 40MHz
Range 2: 40 - 190MHz
Range 3: 190 - 1400MHz
Range 4: 1400 - 6000MHz

I set up the beat frequency readout in various configurations to troubleshoot and have recorded my observation (attachments). The amplifiers in all cases is just a single ZFL-500LN.

There seems to be a problem with the RF amplifier and the frequency counter when they are set together. I am not able to figure it out and stuck right here

Attachment 1: schematic for readout and corresponding observations

Attachment 2: Oscilloscope screen snapshot for schematic 3

Attachment 3: Spectrum analyzer screen snapshot for schematic 3

More info: RFPD used is Thorlabs FPD310 and frequency counter is Mini Circuits UFC-6000. The RF amplifier has decoupling capacitors soldered across the power supply.

Attachment 1: FOL_trouble.pdf
Attachment 2: IMAG0341.jpg
Attachment 3: IMAG0342.jpg
11127   Tue Mar 10 14:47:05 2015 manasaUpdatePSLPMC relocked

PMC was locked in a bad state. FSS slow actuator adjust was at ~ -0.7 and PZT voltage at ~45.

So I set these right by moving the appropriate sliders and relocked it. FSS slow actuator adjust brought back to zero and PZT voltage ~115. PMC trans after relock is 0.789.

11128   Tue Mar 10 17:48:07 2015 manasaUpdateGeneralFOL troubleshooting

[Koji, Manasa]

This problem was solved by changing the Frequency Counter range settings.

Frequency counter automatic range setting has been modified and now the range can be manually set depending on the input frequency. New codes have been written to do this. The scripts will be polished and wrapped up shortly.

Quote:

Figuring out the problem with frequency counter readouts:

 RF amplifier box: The frequency counter was setup to read the beat frequency after amplification of the RFPD signals. The output as seen on the frequency counter screen as well as the epics values was intermittent. Also, locking the arms and changing the end laser frequencies did not change the frequency counter outputs. It looks like the RF amplifier is oscillating (Oscillating frequencies were ~107 MHz and 218 MHz) and the input circuit needs to be modified and the connections need better insulation. As of now, I have connected the RFPD outputs to the frequency counter sans any amplification and we are able to get a readout of the beat frequency at > 40MHz (Frequency counter requires much higher amplitude signals for frequencies lower than that).

The frequency counter has 4 ranges of operation:
Range 1 : 1 - 40MHz
Range 2: 40 - 190MHz
Range 3: 190 - 1400MHz
Range 4: 1400 - 6000MHz

I set up the beat frequency readout in various configurations to troubleshoot and have recorded my observation (attachments). The amplifiers in all cases is just a single ZFL-500LN.

There seems to be a problem with the RF amplifier and the frequency counter when they are set together. I am not able to figure it out and stuck right here

Attachment 1: schematic for readout and corresponding observations

Attachment 2: Oscilloscope screen snapshot for schematic 3

Attachment 3: Spectrum analyzer screen snapshot for schematic 3

More info: RFPD used is Thorlabs FPD310 and frequency counter is Mini Circuits UFC-6000. The RF amplifier has decoupling capacitors soldered across the power supply.

11132   Wed Mar 11 15:35:38 2015 manasaUpdateGeneralWaking up the PDFR measurement system

I was around the 1Y1 rack today. Trials were done to get the PDFR of AS55.

 Quote: [EricG, Manasa] We woke up the PDFR measurement setup that has been sleeping since summer. We ran a check for the laser module and the multiplexer module. We tried setting things up for measuring frequency response of AS55. We could not repeat Nichin's measurements because the gpib scripts are outdated and need to be revised.  PDFR diode laser was shutdown after this job.

11145   Thu Mar 19 14:37:17 2015 manasaConfigurationIOOIMC relocked

The autolocker was struggling to lock the IMC. I disabled the autolocker and locked the IMC manually. It seems happy right now.

With PMC trans at 0.717 counts, the IMC trans sum is ~15230.

 Quote: The MC autolocker hasn't been so snappy recently, and has been especially fussy today. Previously, the mcup script was triggered immediately once the transmission was above a certain threshold. However, this could waste time if it was just an errant flash. Hence, I've added a 0.5 second delay and a second threshold check before mcup is triggered.  After breaking the lock 5ish times, it does seem to come back quicker.

11164   Tue Mar 24 10:53:30 2015 manasaUpdateGeneralScripts updated to the svn

I found that the scripts in FOL and PDFR directories were not in the svn. These were added to the svn.

11166   Tue Mar 24 15:22:12 2015 manasaUpdateComputer Scripts / ProgramsNew slow channels for FOL

[Koji, Manasa]

I have created new slow channels for FOL. To do so, I have edited the fcreadout.db file in Domenica and the C0EDCU.ini file in /chans/daq

Domenica and frame builder were restarted after the edits.

Koji has moved the following files from /opt/rtcds/caltech/c1/chans/daq/ to /opt/rtcds/caltech/c1/chans/daq/trash  as they are not being used anymore.

C0EDCU1.ini C1EDCU_X00.ini C1EDCU_X10.ini C1EDCU_X14.ini C1X00.ini C1X10.ini C1X99.ini

11189   Wed Apr 1 11:42:30 2015 manasaUpdateComputer Scripts / ProgramsPID script in python

Since none of us here are experts in pearl, I have put together a python script for a simple PID controller. This can be imported into any main scripts that will run the actual PID loop. The script, PID.py, exists in /scripts/general/

11199   Fri Apr 3 14:57:38 2015 manasaUpdateSUSBS oplev

The BS oplev has been misbehaving and kicking the optic from time to time since noon. The kicks are not strong enough to trip the watchdogs (current watchdog max counts for the sensors is 135).

I took a look at the spectrum of the BS oplev error in pit and yaw with both loops enabled while the optic was stable. There is nothing alarmingly big except for some additional noise above 4Hz.

I have turned the BS oplev servo OFF for now.

Attachment 1: BS_oplev_Apr3.png
11209   Wed Apr 8 21:10:55 2015 manasaUpdateGeneralWaking up the PDFR measurement system

I was poking around with the PDFR hardware today.

I moved the Agilent which had its screen projected on the monitor. I have put it back...but please verify the settings before using it for tonight.

11235   Wed Apr 22 11:48:30 2015 manasaSummaryGeneralDelay line frequency discriminator for FOL error signal

Since the Frequency counters have not been a reliable error signal for FOL PID loop, we will put together an analog delay line frequency dicriminator as an alternative method to obtain the beat frequency.

The configuration will be similar to what was done in elog 4254 in the first place.

For a delay line frequency dicriminator, the output at the mixer is proportional to $cos(\theta_{b})$ where $\theta_{b} = 2 \pi f_{b}L/v$

L - cable length asymmetry, fb - beat frequency and v - velocity of light in the cable.

The linear output signal canbe obtained for  $0< \theta_{b}<\pi$

For our purpose in FOL, if we would like to measure beat frequency over a bandwidth of 200MHz, this would correspond to a cable length difference of 0.5 m (assuming the speed of light in the coaxial cable is ~ 2x108m/s.

11236   Wed Apr 22 14:56:18 2015 manasaSummaryGeneralDelay line frequency discriminator for FOL error signal

[Koji, Manasa]

Since the bandwidth of the fiber PD is ~ 1GHz, we could design the frequency discriminator to have a wider bandwidth (~ 500MHz). The output from the frequency discriminator could then be used to define the range setting of the frequency counter for readout or may be even error signal to the PID loop.

A test run for the analog DFD with cable length difference of 27cm gave a linear output signal with zero-crossing at ~206MHz.

Detailed schematic of the setup and plot (voltage vs frequency) will be updated shortly.

11270   Mon May 4 10:21:09 2015 manasaSummaryGeneralDelay line frequency discriminator for FOL error signal

Attached is the schematic of the analog DFD and the plot showing the zero-crossing for a delay line length of 27cm. The bandwidth for the linear output signal obtained roughly matches what is expected from the length difference (370MHz) .

We could use a smaller cable to further increase our bandwidth. I propose we use this analog DFD to determine the range at which the frequency counter needs to be set and then use the frequency counter readout as the error signal for FOL.

Attachment 1: DFD.png
Attachment 2: DFD_resp.png
11272   Mon May 4 12:42:34 2015 manasaSummaryGeneralDelay line frequency discriminator for FOL error signal

Koji suggested that I make a cosine fit for the curve instead of a linear fit.

I fit the data to $V(f) = A + B cos(2\pi f_{b}L/v)$
where L - cable length asymmetry (27 cm) , fb - beat frequency and v - velocity of light in the cable (2*10m/s)

The plot with the cosine fit is attached.

Fit coefficients (with 95% confidence bounds):
A =      0.4177  (0.3763, 0.4591)
B =       2.941  (2.89, 2.992)

Attachment 1: DFD_cosfit.png
11280   Mon May 11 13:21:25 2015 manasaUpdateCDSc1lsp and c1sup not running

I found the c1lsp and c1sup models not running anymore on c1lsc (white blocks for status lights on medm).

To fix this, I ssh'd into c1lsc. c1lsc status did not show c1lsp and c1sup models running on it.

I tried the usual rtcds restart <model name> for both and that returned error "Cannot start/stop model 'c1XXX' on host c1lsc".

I also tried rtcds restart all on c1lsc, but that has NOT brought back the models alive.

Does anyone know how I can fix this??

c1sup runs some the suspension controls. So I am afraid that the drift and frequent unlocking of the arms we see might be related to this.

P.S. We might also want to add the FE status channels to the summary pages.

11281   Mon May 11 13:26:02 2015 manasaUpdateIMCMC_F calibration

The last MC_F calibration was done by Ayaka : Elog 7823

 Quote: And does anyone know what the MC_F calibration is?

11282   Mon May 11 14:08:19 2015 manasaUpdateCDSc1lsp and c1sup removed?

I just found out that c1lsp and c1sup models no more exist on the FE status medm screens. I am assuming some changes were done to the models as well.

Earlier today, I was looking at some of the old medm screens running on Donatella that did not reflect this modification.