A few weeks ago, on Jul 24, Rana and I measured the phase noise of the FSS frequency box (aka the 'Kalmus Box'). See elog entry 3286.
That time, for some reason, we measured a phase noise higher than we expected; higher than that of the Marconi.
I repeated the measurement today using the SR785 spectrum analyzer. Here is the result:
(The measurement of July 24 on the plot was not corrected for the loop gain. The UGF was at about 30 Hz)
To make sure that my measurement procedure was correct, I also measured the combined phase noise of two Marconis. I then confirmed the consistency of that with what already measured by other people in the past (i.e. Rana elog entry 823 in the ATF elog).
This time the noise seemed reasonable; closer to the Marconi's phase noise, as we would expect. I don't know why it was so bad on July 24.
The shoulder in the Marconi-to-Marconi measurement between 80Hz and 800Hz is probably due to the phase noise of the other Marconi, the one used as LO.
I'm going to repeat the measurement connecting the setup to the DAQ, and locking the Marconi to the Rubidium standard.
Ultimately, the goal is to measure the phase noise of the new Sideband Frequency Generation Box of the 40m Upgrade.
I am feeling that it is ok to carefully make new holes and threads as far as the holes do not penetrate the plate.
The thickness of the plate can be measured by the four holes at the corners.
Crane balancing at the south end is continuing today.
I measured the phase noise of the LO output of the FSS box from the DAQ. I'm attaching the results.
As we expected, the measurement is limited by the internal phase noise of the Marconi.
The measurement was done as shown in this diagram.
We copied the latest x02 to c1x02 and modified to our the config block in it.
We removed gds_node_id. We just have one number now, the dcuid, which is unique for each controller, simulated plant and IOP. Set site to C1 and host to c1sus.
Alex made the latest awgtpman backwards compatible, and checked that into svn.
We installed the latest framecpp onto c1sus from www.ldas-sc.ligo.caltech.edu/packages/ using wget.
wget www.ldas-sc.ligo.caltech.edu/packages/framecpp-1.18 and then used make.
This let us compile diagd on c1sus, using the command make stand in the /advLigoRTS/build area.
We copied gds from the seiteststand over at handford and are trying to build that on megatron. However, there's a bunch of packages we need for it to install properly. Alex said he'd work on that later, possibly trying to make some portable binaries.
Checked out the latest dataviewer into /opt/rtcds/caltech/c1/core/daq, however its not quite working yet either. This is another thing Alex said he'll work on later.
We are also going to test Alex and Rolf's kernel patch over on c1iscex on Centos base kernel (apparently they've been using Gentoo up at hanford for the test stands...) and see how that works.
The differences between this setup and the one used previously is the lack of the 50 Ohm terminator in the mixer output and
that the SR560 readout with the G=100 should come before the first SR560 via T, so as not to be spoiled by the high noise of the G=1 SR560.
I removed the 50 Ohm in-line terminator when I did the measurement with the SR785. The for some reason I was getting more noise, so I removed it.
Now I put it back in and I did the measurement with the DAQ. I also moved the SR560 that amplifies the signal for the DAQ, Tee'ing it with the input of the in-loop SR560.
Now the setup looks like this:
And the phase noise that I measure is this:
Comparing it with the phase noise measured with the previous setup (see entry 3506), you can see that the noise effectively is reduced by about a factor of 2 above 10 Hz.
With the setup now working, we should now test the power filtering for the crystal and amplifier.
More PSL progress.
The new laser was raised to a 4 inch beam height using basically the most randomly thrown together method possible. (It'll work just fine for aligning things, but we seriously need to get a nice block made.) The PMC and the nice Osamu-mirror mount to go into the PMC also have temporary risers, so we'll need to replace them with the real deal as soon as we get things back from the shop.
So far we've got (1) the lens after the laser, (2) a Half Wave Plate (no quarter wave plate yet), (3) steering mirror that will go after the EOM, (4) 2 steering mirrors to get into the PMC, in addition to all of the stuff that we did the other day. With all of this stuff we've got the beam hitting the 1st PMC mirror. We still don't have the EOM and AOM in the beam path however.
To get the rough alignment that we did, we turned on the new 2W NPRO, operating at the minimum power we could see on a card. We turned it off after use, so it is still off. Steve, we left the cable for the interlock sitting on the PSL table on the NW corner....can you please hook it up tomorrow? Also, after the interlock is installed we should go back to regular running laser hazard mode.
Rolf has recently written a document describing how one should fill out an IO chassis and how the numbering works out. This can be found in the DCC at Rolf's PCIe numbering guide (T1000523).
Basically it works out that slot 1 corresponds to PCIe number 1, but slot 2 corresponds to PCIe number 6. And so forth. The following table gives a quick summary.
Joe and Kiwamu:
We found one bug in the RCG code, where the second input for the CDO32 part (32 binary output) was simply a repeat of the first input, and totally ignored the second input. This was fixed in the /advLigoRTS/src/epics/util/lib/CDO32.pm file by changing
$calcExp .= $::fromExp;
$calcExp .= $::fromExp;
This fix has been added to the svn. Unfortunately, while we have a single working binary output module, the 2nd and later modules do not seem to be responding at all. We've done the usual swaping parts of the path in both software and hardware and can't find any bad pieces in our model files or the actual hardware. That leaves me wondering about the c code, specifically if the CDO32Output, CDO32Output, and so forth array entries in the code are being handled properly. I'll try to get some thoughts on it from Alex tomorrow.
Koji and I inspected and photographed the laser after opening up its case. I then drilled the clearance holes in the 4 corners and tapped holes for 1/4-20. I was careful to tap with the laser sideways, to avoid shavings getting into the laser and suctioned out as much of the pieces as I could. The laser is now mounted on some bad 1/4-20 based NewFocus style pedestals. The riser block can now be made with 1/4-20 through holes and the laser will sit on its for corner feet. We'll make the base aluminum to avoid differential CTE based stress in the laser base.
We checked the level of the laser. With the new mounting the beam is level to within ~1 mrad and has a 4" beam height.
I've mounted the Faraday Rotator from the old MOPA. It has 8-32 mounting holes (who's shafts are curiously not parallel). We need an aluminum block of the proper height (2 3/4" ??) to make a permanent solution.
I've also mounted the thin-film polarizer. This works well, but it also needs a block machined to get the mounting to be less Mickey Mouse.
Pockel Cell for phase correction and 35.5 MHz PMC modulation
The EOM is mounted as before on the angle bracket to align it for P-pol light. The beam now goes cleanly through there. No further mounting hardware required.
The 2 lenses in the 'mode matching telescope' between the laser and the PMC are in place, but not placed with any accuracy.
By sheer luck, I saw the PMC flashing in the TEM27 mode without any alignment from me. Next step is to get the lens positions tuned and then do the beam scan on the beam going towards the PMC to verify the approximate mode matching. This is all crude, but I just want to get the beam going into the vacuum as fast as possible.
Rana and I were poking around on the PSL table today, getting a few more items raised to the correct height.
I checked the polarization state of the new NPRO by using a HWP to minimize the transmission through a PBS cube, and then compared the power transmitted through the cube vs. reflected. When the NPRO current was 0.772 \pm 0.001 (as read on the LCD), the transmission through the cube was 1.44mW, while the reflected was 10.53mW. The reading of the Ophir power meter with no incident light was 0.03mW. This factor of 10 means that the NPRO beam is ~10% circularly polarized and ~90% linearly polarized. In order to improve the beam, we need a Quarter Wave Plate, which it turns out we don't have. We need a QWP!
After that, using the linearly polarized part of my beam (maximizing the transmission through the PBS by rotating my HWP by 45deg), I tried to tune the angle of the polarizers that Rana pulled out of the MOPA. I think I'm confused / too tired, because I can only get the polarizer to reflect a bunch of light, and I can't get it to pass any significant amount of light through, no matter where in its actuation range I put it (It's on a rotation stage with a few degrees of range). It should just be a Brewster's Angle thing, and since I already have P-pol coming through the BS cube, this shouldn't be so hard.....
In any case, it may not be useful to do the final fine tuning of these polarizers until they are in their final places. The hacky stack of mounts that I have has some slop in the position / alignment of the base of the polarizer, so no matter what we'll have to redo the tuning after the mounts are finalized.
To bypass the polarizer issue, I just used cubes. One I took from the FSS-Refcav path and the other from the power control part of the old MOPA, just downstream of the MOPA's periscope.
We'll swab these out with the thin-film polarizers after we get the mounts made.
With the cubes in, I also installed the Faraday + its 1/2-wave plate. The transmission looks good and we're getting into the PMC and its flashing a TEM00 mode sometimes. I set up a signal generator to drive the SLOW actuator by 1 FSR at 0.1 Hz.
I have set up a PMC transmission camera and transPD so that its easy to align. The flashing mode already allows us to align most of the rest of the table (except FSS).
Our next step should be to run the cables for locking the PMC:
On Tuesday, we need to make sure that all of our mounts' drawings are in the cue for the shop. I'll put the list of mounts onto the PSL upgrade wiki page.
We also have to come up with a plan for wiring some of the 2W NPRO's channels into the cross-connect so that we can have some laser channels recorded by EPICS.
I have reviewed the suspension model of C1SUS and refined it.
It is comaptible to the current one but has minor additions.
We must remember that we are using the Rev.B SOS Coil Drivers and not the Rev. A.
The main change from A->B was the addition of the extra path for the bias inputs. These inputs were previously handled by the slow EPICS system and not a part of the front end. So we used to have a separate bias screen for these than the bias which is in the front end. The slow bias is what was used for the alignment to avoid overloading the range of the main coil driver path.
Last week I noticed that the high power amplifiers in the Frequency Generation Box became hot after 2 hours of continuous operation with the lid of the box closed. When I measured their temperature it was 57C, and it was still slowly increasing (~< 1K/hr).
According to the data sheet, their maximum recommended temperature is 65C. Above that their performances are not guaranteed anymore.
These amplifiers aren't properly dissipating the heat they produce since they sit on a plastic surface (Teflon), and also because their wing heat dissipator can't do much when the box is closed. I had to come up with some way to take out their heat.
The solution that I used for the voltage regulators (installing them on the back panel, guaranteeing thermal conduction but electrical isolation at the same time) wouldn't be applicable to the amplifiers.
I discussed the problem with Steve and Koji and we thought of building a heat sink that would put the amplifier in direct contact with the metal walls of the box.
After that, on Friday I've got Mike of the machine shop next door to make me this kind of L-shaped copper heat sink:
On Saturday, I completely removed the wing heat dissipator, and I only installed the copper heat sink on top of the amplifier. I used thermal paste at the interface.
I turned on the power, left the lid open and monitored the temperature again. After 2 hours the temperature of the amplifier had stabilized at 47C.
Today I added the wing dissipator too, and monitored again the temperature with the lid open. then, after a few hours, I closed the the box.
I tracked the temperature of the amplifier using the temperature sensors that I installed in the box and which I have attached to the heat sink.
I connected the box temperature output to C1:IOO-MC_DRUM1. With the calibration of the channel (32250 Counts/Volt), and Caryn's calibration of the temperature sensor (~110F/Volt - see LIGO DOC # T0900287-00-R), the trend that I measured was this:
The heat sink is avoiding the amplifier to overheat. The temperature is now compatible with that of the other component in the box (i.e., crystal oscilaltors, frequency multiplier).
Even with the lid closed the temperature is not too high.
Two things remain untested yet:
1) effect of adding a MICA interface sheet between the heat sink and the wall of the chassis. (necessary for gorund isolation)
2) effect of having all 3 amplifiers on at the same time
I am considering opening air circulation "gills" on the side and bottom of the chassis.
Also we might leave the box open and who ever wants can re- engineer the heat sink.
- Ideally we would like that the heat sink had the largest section area. A brick of metal on top the amplifier would be more effective. Although it would have added several pounds to the weight of the box.
- We need these amplifiers in order to have the capability to change the modulation depth up to 0.2, at least. The Mini-Circuit ZHL-2X-S are the only one available off-the-shelf, with a sufficiently low noise figure, and sufficiently high output power.
Here are the results of my phase noise measurements on the 7 outputs of the Frequency Generation Box. (BIN=95L applied by DTT). See attached pdf for a higher definition picture.
The plot shows that the phase noise of the 11 MHz outputs (Source, EOM modulation signal, Demodulation signal) is as low as that of the Marconi. The Marconi is limiting my measurement's resolution.
The mode cleaner signal's oscillator (29.5 MHz output, blue trace) is higher than the 11MHz above 1KHz.
The 55MHz signals have all the same phase noise (traces overlapped), and that is higher than the 11 MHz ones from about 100Hz up. i don't know what's going on.
I need to use the spare 11MHz Wenzel crsytal to have a better reference source for the measurement.
We need a distribution unit in the LSC rack to: 1) collect the demod signals coming from the Frequency Generation Box 2) adjust the power level 3) generate 2nd harmonics (for POP) 4) distribute the demod signals to the single demodulation boards.
The base line plan is the following:
The box can be build up gradually, but the priority goes to these parts:
I need help for this work. I know exactly how to do it, I just don't have the time to do it all by myself.
Besides the Distribution Box, the demodulation part of the upgrade would still require two steps:
1) upgrade the Band Pass Filters of the demodulation boards (I have all the parts)
2) cabling from the distribution box to the demod board (one-afternoon kind of job)
As noted previously, we were having problems with getting multiple 32 channel binary output cards working. Alex came by and we eventually tracked the problem down to an incorrect counter in the c code. This has been fixed and checked into the CDS svn repository. I tested the actual hardware and we are in fact able to turn our test LEDs on with multiple binary output boards.
Alex and I also looked at the non-functional IO chassis (the one which wouldn't sync with the 1PPS signal and wasn't turning on when the computer turned on. We discovered one corner of the trenton board wasn't screwed down and was in fact slightly warped. I screwed it down properly, straightening the board out in the process. After this, the IO chassis worked with a host interface board to the computer and started properly. We were able to see the boards attached as well with lspci. So that chassis looks to be in working condition now.
Onwards to the RFM test.
We ran the cables for the PMC: The RF cable for the 35.5 MHz drive was cheap and so we swapped the 29.5 MHz cable for it.
There now remain 1 RG-174 cable to drive the FSS PC (21.5 MHz) and 3 Heliax for the Kiwamu Tri-Mod EOM (11, 29.5, and 55 MHz).
We also changed the BLACK HV drive cable for the RED one (previously used for the MZ). All HV cables MUST be RED.
The BLACK cable is now used for the PMC_REFL DC.
The Heliax cables are routed onto the table - it remains a Alberto/Kiwamu job to strain relieve them and attach them to the TriMod box and EOM in the morning.
The PMC is locked and we did some partially bootless alignment and mode-matching. It locks easily on a TEM00 mode (with very poor visibility), but the
rest of the beam train can now be aligned while Valera does the PMC matching mambo.
Also, Kiwamu has modified the layout drawing to add the green PLL stuff. This has collapsed the reference cavity's wave function placing it close to its original position.
WE (maybe Valera and Steve) can now put the reference cavity back on the table.
I put some green stuff on the layout drawing.
I continue to refine the positions of these stuff.
1. I flipped the reference cavity. So now the cavity is sitting on the left hand side of the layout.
2. I removed the ISS stuf. We should think about where ISS should be.
Also, Kiwamu has modified the layout drawing to add the green PLL stuff. This has collapsed the reference cavity's wave function placing it close to its original position.
I updated parse_mdl_to_ipc.py to correctly work with the 3 new cdsIPCx parts, namely cdsIPCx_PCIE (for dolphin connections), cdsIPCx_RFM (for our traditional reflected memory connections), and cdsIPCx_SHMEM (local shared memory on the computer). These parts replaced cdsIPCx awhile back (see here ).
The code now correctly counts each type independantly with regards to ipcNum (I.e. you can have ipcNum = 0 for RFM and ipcNum = 0 for SHMEM for example).
I also went in and modified a few sections of the feCodeGen.pl (in /opt/rtcds/caltech/c1/core/advLigoRTS/src/epics/util/) so as to properly assign names to matrix adl files, matrix of filter bank adl files, and filter bank adl files.
I played with the particle counter this morning. Now it's running and reading the correct numbers on the old COCHECKLIST.adl medm screen.
However, it can not be seen with dataviewer.
Koji just rebooted the frame builder and the problem was solved.
I started mode matching of the beam going to IMC. The work is still going on.
According to Rana's calculation (see here), I put the first lens (f=200mm) in between two steering mirrors after PMC.
The distance from PMC to the first lens was adjusted by using a metal ruler. So I believe the accuracy is something like 1mm.
I aligned the beam path going through the broadband EOM and the mode matching lenses.
I could find the optimum position for the second lens (f=-150mm) by sliding the position of the lens and measuring the mode after it.
But the optimum position looked a bit far from the EOM. It's off by about 3-4 inch from the designed position.
Somehow I feel that the beam before the second lens goes with a smaller divergence angle than that of designed.
So tomorrow I am going to restart the work from checking the mode before the second lens.
Maybe at first I should measure the mode without going through the EOM because it changes the waist position and makes the system not straightforward.
Innolight 2W 1064nm main laser was turned off for more enclosure related work.
The electrician re rooting the power- conduit to the interlock under the floor and bring it through the new concrete tunnel.
Emergency laser power shut off switch was tested at entry door 104M. It worked fine.
No laser glasses required. Laser will be turned back on around 11 am today.
Atm1, AC power line to enclosure and interlock was extended.
Atm2, 24V line to interlock rerouted
Atm3, job is completed
SAFETY GLASSES REQUIRED ! SAFETY GLASSES REQUIRED!
The laser is turned on. Injection current set to 0.871A.
Actually some one turned the laser off last night and did not enter it into the elog ! Burned toast award is granted !
Please come forward voluntarily.
I turned off/on the power to the accelerometers in order to re rout their connections. I found cable connector body-nut #3 loose to Accelerometer 2X This connector should be checked for solid performance.
I measured the amplitude noise of the source outputs and the EOM outputs of the Frequency Generation box.
the setup I used is shown in this diagram:
(NB It's important that the cables from the splitter to the RF and LO inputs of the mixers are the same length).
The results of the measurements are shown in the following plot:
1) both Crystals (29.5MHz and 11MHz) have the same noise
2) the 55MHz source's noise is bigger than the 11 MHz (~2x): the frequency multiplication and amplification that happen before it, add extra noise
3) the noise at EOM outputs is ~2x bigger than that of the relative sources
When I have the chance, I'll plot the results of my calculations of expected noise and compare them with the measurements.
I've been working on updating the suspensions model, incorporating Koji's refinements as well as trying to simplify the model and making it less cluttered.
This had the side benefit of making an incorrect connection obvious. I had incorrectly wired the ASCPIT input to be summed into the yaw path, and the ASCYAW input into the pitch path. This has been corrected.
I've finished a single optic, and now I am in the process of propagating the changes to all the optics, as well as cleaning up the overall diagram using Rolf's new tags, which make things much less cluttered. I've attached a screenshot of the PRM optic control model, and will be updating the Matlab web export once I've updated the full model.
I turned off the laser last night to protect against the electricians. but failed to elog it. I accept the burnt toast completely.
- The PMC REFL PD was moved from the temporary location to the one called for by the PSL layout (picture attached). The leakage beams were dumped.
- The FSS reference cavity was aligned using temporary periscope and scanned using NPRO temperature sweep. The amplitude of the sweep (sine wave 0.03 Hz) was set such that the PMC control voltage was going about 100 V p-p with. With rough alignment the visibility was as high as 50% - it will be better when the cavity is locked and better aligned but not better than 80% expected from the mode astigmatism that Tara and I measured on Thursday. The astigmatism appear to come from the FSS AOM as it depends on the AOM drive. We reduced the drive control voltage from 5 V to 4V beyond that the diffraction efficiency went below 50%. The FSS REFL PD was set up for this measurement as shown in the attached picture. There is also a camera in transmission not shown in the picture.
Kiwamu and I found that the first lens in the PMC mode matching telescope was mislabeled. It is supposed to be PLCX-25.4-77.3-C and was labeled as such but in fact it was PLCX-25.4-103.0-C. This is why the PMC mode matching was bad. We swapped the lens for the correct one and got the PMC visibility of 82%. The attached plot shows the beam scans before and after the PMC. The data were taken with the wrong lens. The ABCD model shown in the plot uses the lens that was there at the time - PLCX-25.4-103.0-C. The model for the PMC is just the waist of 0.371 mm at the nominal location. The snap shot of the ABCD file is attached. The calculation includes the KTP for FI and LiNb for EOM with 4 cm length. The distances are as measured on the table.
The attached plot shows the beam scans of the beam leaking from the back mirror of the PMC to the BS cube that first turns the S-pol beam 90 deg to the AOM and then transmits the AOM double passed and polarization rotated P-pol beam to the reference cavity. The beam from the PMC is mode matched to the AOM using a single lens f=229 mm. The ABCD file is attached. The data were taken with VCO control voltage at 5 V. We then reduced the voltage to 4 V to reduce the astigmatism. Tara has the data for the beam scan in this configuration in his notebook.
The beam from AOM is mode matched to the reference cavity using a single lens f=286.5 mm. The ABCD file is attached.
I measured the RF power output of the VCO Driver box as a function of slider value. I measured using the Gigatronics Handheld power meter and connected to the AOM side of the cable after the white Pasternak DC block.
* at low power levels, I believe the waveform is too crappy to get an accurate reading - that's probably why it looks non-monotonic.
* the meter has a sticker label on it saying 'max +20 dBm'. I went above +20 dBm, but I wonder if maybe the thing isn't linear up there...
I've started a wiki page under the Upgrade 09/New CDS section regarding known bugs and pending feature requests for the Real Time Code Generator. It can be found at http://lhocds.ligo-wa.caltech.edu:8000/40m/Bugs_and_Pending_Feature_requests_for_the_RCG. If you have any ideas to improve the RCG or encounter a bug in the code generation process (say a particular part doesn't work inside subsystems for example), please note them here.
Currently there are bugs with excitation points (they don't work inside of a subsystem block) and tags (they don't respect scope and only 1 "from" tag for each "goto" tag connected to the output of a subsystem block).
I uploaded all the material about the RF frequency Generation Box into the SVN under the path:
I structured the directory as shown in this tree:
I'm quickly describing in a section of the Rf system upgrade document with LIGO # T1000461.
I have been working on the mode matching lenses which are sitting after the boradband EOM.
Last Friday I checked the mode profile after the first mode matching lens (f=-150mm). The measured mode was good.
According to the calculation done by ABCD software, the waist size is supposed to be 80.9 um after that lens.
The measured waists are 80.5 um for the vertical mode and 79.4 um for the horizontal mode.
The screenshot of the ABCD's result and the plot for the mode measurement are shown below.
I didn't carefully check the mode after the last convex lens (f=200mm), but it must be already good because the beam looks having a long rayleigh range.
Now the beam is reflected back from MC1 and goes to the AP table since I coarsely aligned the beam axis to the MC.
/**** fitting result ****/
w0_v = 80.4615 +/- 0.1695 [um]
w0_h = 79.4468 +/- 0.1889 [um]
z_v = -0.115234 +/- 0.0005206 [m]
z_h = -0.109722 +/- 0.0005753 [m]
The IR sensitive Olympus 570 camera gives us a really nice view of these IR beams. Its actually a lot better than what you can get with the analog IR viewers:
I turned ON the laser at the X end station, which had been OFF for several weeks because of the crane business.
Now the green beam hits the ITMX and I got a reflection back to the end table.
This green beam will be a nice reference when we install the green periscope in the chamber.
If it's necessary, feel free to correct the alignment of the green beam during my absence.
I completed a LIGO document describing design, construction and characterization of the RF System for the 40m upgrade.
It is available on the SVN under https://nodus.ligo.caltech.edu:30889/svn/trunk/docs/upgrade08/RFsystem/RFsystemDocument/
It can also be found on the 40m wiki (http://lhocds.ligo-wa.caltech.edu:8000/40m/Upgrade_09/RF_System#preview), and DCC under the number T1000461.
- connected the TTFSS cables (FSS fast goes directly to NPRO PZT for now)
- measured the reference cavity 21.5 MHz EOM drive to be 17.8 dBm
- turned on the HV for the FSS phase correcting EOM (aka PC) drive
- connected and turned on the reference cavity temperature stabilization
- connected the RefCav TRANS PD
- fine tuned the RefCav REFL PD angle
The RefCav is locked and aligned. I changed the fast gain sign by changing the jumper setting on the TTFSS board. The RefCav visibility is 70%. The FSS loop ugf is about 80 kHz (plot attached. there is 10 dB gain in the test point path. this is why the ugf is at 10 dB when measured using in1 and in2 spigots on the front of the board.) with FSS common gain max out at 30 dB. There is about 250 mW coming out of the laser and 1 mW going to RefCav out of the back of the PMC. So the ugf can be made higher at full power. I have not made any changes to account for the PMC pole (the FSS is after the PMC now). The FSS fast gain was also maxed out at 30 dB to account for the factor of 5 smaller PZT actuation coefficient - it used to be 16 dB according to the (previous) snap shot. The RefCav TRANS PD and camera are aligned. I tuned up the phase of the error signal by putting cables in the LO and PD paths. The maximum response of the mixer output to the fast actuator sweep of the fringe was with about 2 feet of extra cable in the PD leg.
I am leaving the FSS unlocked for the night in case it will start oscillating as the phase margin is not good at this ugf.
Brilliant! This is the VERY way how the things are to be conquered!
The RefCav is locked and aligned. I changed the fast gain sign by changing the jumper setting on the TTFSS board. The RefCav visibility is 70%. The FSS loop ugf is about 80 kHz (plot attached) with FSS common gain max out at 30 dB. There is about 50 mW coming out of the laser and a few mW going to RefCav out of the back of the PMC. So the ugf can be made higher at full power. I have not made any changes to account for the PMC pole (the FSS is after the PMC now). The FSS fast gain was also maxed out at 30 dB to account for the factor of 5 smaller PZT actuation coefficient - it used to be 16 dB according to the (previous) snap shot. The RefCav TRANS PD and camera are aligned. I tuned up the phase of the error signal by putting cables in the LO and PD paths. The maximum response of the mixer output to the fast actuator sweep of the fringe was with about 2 feet of extra cable in the PD leg.
We removed the Lightwave MOPA Controller from 1X1 (south) It was a real painfully messy job to pull out the umbilical.
Note: the umbilical is shading it plastic cover. It is functional but it has to be taken out side and cleaned. Do not remove it from it's plastic bag in a clean environment.
Now Joe has room for IOO chassy in this rack.
We also removed the Minco temp controller and ref. cavity ion pump power supply.
We removed the Lightwave MOPA Controller, PA#102, NPRO206 power supply to make room for the IOO chassy at 1X1 (south) rack.
The umbilical cord was a real pain to take out. It is shading its plastic cover. The unused Minco was disconnected and removed.
The ref. cavity ion pump controller- power supply was temporarily taken out also.
The attached plots show the PMC cavity line width measurement with 1 mW and 160 mW into the PMC. The two curves on each plot are the PMC transmitted power and the ramp of the fast input of the NPRO. The two measurements are consistent within errors - a few %. The PMC line width 3.5 ms (FWHM) x 4 V / 20 ms (slope of the ramp) x 1.1 MHz / V (NPRO fast actuator calibration from Innolight spec sheet) = 0.77 MHz.
Here is the output of the calculation using Malik Rakhmanov code:
modematching = 8.4121e-01
transmission1 = 2.4341e-03
transmission2 = 2.4341e-03
transmission3 = 5.1280e-05
averageLosses = 6.1963e-04
visibility = 7.7439e-01
fw = 0.77e6; % width of resonance (FWHM) in Hz
Plas = 0.164; % power into the PMC in W
% the following number refer to the in-lock cavity state
Pref = 0.037; % reflected power in W
Ptr = 0.0712; % transmitted power in W
Pleak = 0.0015; % power leaking from back of PMC in W
Two SOS suspensions for the ETMs were disassembled and packed for cleaning and baking by Bob.
These suspensions have been stored on the X end flow bench long years, and looked quite old.
They have some differences to the modern SOSs.
- The top suspension block is made of aluminum and had dog clamps to fix the wires.
- The side bars are not symmetric: the side OSEM can only be fixed at the right bar (left side in the picture).
- EQ stops were made of Viton.
- One of the tower bases seems to have finger prints (of Mike Zucker?).
I found that the OSEM plates had no play. We know that the arrangement of the OSEMs gets quite difficult
in this situation. Therefore the holes of the screws were drilled with the larger drill.
We decided to replace all of the screws to the new ones as all of the screws are Ag plated and got corroded
by silver sulfide (Ag2S). I checked our stock in the clean room. We have enough screws.