What we need more to make the work better/easier in/around the HEPA table:
Task Completed Today :
D2200122 Spacer Rings have been machined and ready for C&B
I walked over to the GALCIT Shop today after receiving an email notifying me that the Spacer Rings are ready. We received 5 rings instead of 4 because the machinist made a mistake on one and was a couple thousanths of an in thicker. This ring is marked red on the photo in attachment #1. I have given these rings to Maty and she will take care of the C&B process since I will be out tomorrow. She said she expect them to be done sometime early next week.
The North siderail of the cleanroom has been raised.
I raised the North Siderail of the cleanroom to give us some more freedom moving the steel cart around in the cleanroom. This also allowed me to rotate the cart and add a bit more space inside. While doing this I had the particle counter running and 0.5 Micron count < 50 and the 0.5 Micron count < 10.
Parts SM05RR, LMR1V, D2300352-01, -02, -03, -04, and D2300208, D2300209, D2300210 have been C&Bed.
SM05RR, LMR1V, D2300352-01, -02, -03, -04, D2300208, D2300209, D2300210 are ready as of today. These have been placed in a plastic box on the middle space of the newly added steel cart. The Plastic boxes have the DCC/Part number on top so you will know what parts are inside.
A New Cart has been Cleaned and added for working purposes to the cleanroom
I brought the steel cart over from the shed area. I thoroughly wiped it down with IPA after cleaning with Windex and a rag. I also used the air gun to blow of any heavy dust from the wheels. I placed foil over each level of the cart and wiped down again with IPA. After, I made some AntiStat curtain around the cart to keep out anything heavy. Here are the plastic boxes containing parts SM05RR, LMR1V, D2300352-01, -02, -03, -04, D2300208, D2300209, D2300210.
I went through the inventory list and the parts in hand to figure out what was still missing
The list was made on E2200464, and the PDF snapshot was added to this entry.
- Setup the fiber protection and stray beam shields
- Replaced brand new wedged Y1-45P mirrors used in the OMC input path with stock Y1-45S mirrors. The wedged Y1-45Ps are going to be used for the optics on the BHD platform.
Note: 45S mirrors are the same as 45Ps, but just their coating precision was not enough for 45P. So most of the cases 45S is sufficient for 45P purpose.
- All the remaining mirrors / CCDs / a lense / an RF PD (PDA-10) were setup and aligned.
- Found a DS345 is broken. The sinusoidal output does not swing and only has weird constant offsets dependent on the setting ==> need fix.
- An old analog function generator was brought for laser PZT scan test.
- Fast PZT cavity scan test: fine alignment & prelim visibility: REFL PD DS unlocked 5.50V vs TEM00 230mV -> estimated mode matching 95~96%
- When the OMC was detached from the kinematic mount and returned to the position: Relection at TEM00 230mV -> 1V. This corresponds to ~15% degradation of the alignment.
- OMC retainer screws (white PTFE screws) to hold the OMC vertically deforms the breadboard and cause the misalignment. Use something compliant or just release the screws.
The OMC was locked with Moku Pro.
Attachment 1: Electrical setup. The RF part of the REFL PD signal was fed into Moku pro, while the DC part was monitored on a scope.
Attachment 2: Servo setup. The modulation amplitude is 100mV.
Attachment 3: Image rejection LPF setup
Attachment 4: Laser PZT servo during lock acquisition
Attachment 5: Laser PZT servo for stational operation
Attachment 6: Laser Temp servo setting
Attachment 7: CCD Images during lock. The REFL is still limited by the mode mismatching component.
Attachments 8/9: The REFL locked / unlocked = 340mV/5.4V = 0.06 --> Mode Matching 94%
Continued on the BHD Optics Prep:
The following mounts were prepared (they are not 100% tightened yet)
- OMC Refl Mirror Mounts: OMCiRj (i=1,2, j=1,2,3)
- HWP (fixed) -> a thread adapter is missing
- HWP Actuator
We'll extract LO3/LO4/AS2/AS3/BHDBS from the ITMY chamber.
Fixed HWP mount had very thin room at the center. I wasn't sure if I could mount the 1/2" HWP in it. Fortunately the HWP was quite thin (~1mm) and it just barely fit. (Attachments 2/3)
The fixed HWP mount had no 8-32 to 1/4-20 thread adapter.
I'm asking the C&B of the adapters. (Attachment 4)
- AS2 2" post is being C&Bed
- LO4 2.5" post is being C&Bed
- BHDBS spacer ring is coming back from C&B soon
- BHDBS 2.5" post is being C&Bed
- Faraday Rotater Base was ordered. Waiting for the delivery.
Attachment 1 shows the labeled optics on the ITMY table (from Koji). I recorded the initial e-bubble reading on the ITMY table: (x,y) = (0.03; 0.17). See Attachment 5 for orientation of the e-bubble (from chamber door: x-axis left to right; y-axis front to back).
(x,y) = (0.03; 0.17).
I first cleared the extra steering mirrors (marked SM in Attachment 1). The e-bubble reading after clearing steering mirrors was: (x,y) = (0.03; 0.18). Note that fluctuations of 0.01 are common for the e-bubbles, so this is a negligible change. The steering mirrors were placed on the XEND flow bench [Attachment 2].
(x,y) = (0.03; 0.18)
Next I removed the BHD optics, in the order of (LO4, LO3, BHD BS, AS3, AS2). This was arbitrary but made it easy to work front-to-back and remember reverse numeric order. These were placed on the BHD cleanroom table behind the OMC platform [Attachments 3, 4]. See attachments for labeled optics.
The final e-bubble reading was: (x,y) = (0.00; 0.20). Similar (small) change in x and y directions. Final state of ITMY table in Attachment 5.
(x,y) = (0.00; 0.20)
Remaining things to do:
Tuning of the OMC locking
The lock became less oscillative.
OMC REFL in-lock: 236mV
OMC REFL unlocked: 5.48
-> Mode-matching: 1-0.236/5.48 = 0.957
By the way, the above in-lock refl level was compared with the refl level with the cavity scan.
10Hz 800mVpp scan -> 524mV
1Hz 800mVpp scan -> 324mV
Locked -> 239mV
I could be indicating the thermal effect?
A bunch of instruments are no longer functioning:
Beam Dump Bases (D1102371), PEEK Shims D1102372, Two 2.5 " pedestals, one 3" pedestal, Thread adapters #8-32 --> 1/4-20, #4-40 -1/2 Socket cap Screws, #4-40 set screws.
I have placed this on the middle stage of the outside cart. They have been labeled and placed on the center platform of the cart outside of the cleanroom.
I've finished more BHD optic mounts:
- Downstream HWP
- Hex beam dump x2
The only remaining mechanics is the Faraday rotator base.
I'll start populating the optics in the mounts so that the final alignment can be done.
One issue I faced with today was that:
One of the BHDBS screws was stripped.
This pivot was supposed to swapped with a picomotor. I knew that these screws were tight and prone to strip the hex. So I carefully worked on it but it happened.
The other screw can still rotate. The pivot is still intact, but it'd be hard to replace it with a picomotor.
The impact is that we lost the horizontal translation of the OMC2 input beam. We have to move the OMC itself to correct the misalignment in the horizontal translation.
How much can we do that??? We inherently have no vertical translation of this beam, so it's not a big deal, maybe.
We'll face this operation when we install the second OMC.
Populating the BHD Optics
OMC mode matching
OMC servo actuator range
We got Faraday Rotator Base (D2200378) and it came back from the C&B.
I tried to build the assembly and was stunned with 2 issues.
1) The VOPO Faraday Rotator Riser (D1600160-v1) has 2" slot spacing, while D2200378 has a thread spacing of 1.5". (Attachment 1)
2) I could not manage to insert helicoils.
I made the investigation about 1). It turned out that it's a version control issue.
It seems that the riser we have is D1600160-v1 and has 2" slot spacing. DCC has this version.
However, the one in SolidWorks Vault was modified to have 1.5" slot spacing. It only exists in SW and even it claims it is V1. 😫
So our options are
a) Make the 1.5" space riser.
b) Make the 2" space base
c) Use as they are. If we rotate the base 90 deg, We can hold the riser with the base. It will become structurally weak as the riser is supported only on one side.
The issue 2) needs opinions from JC and Don. Depending on the assessment of 2), we'll decide which of a)~c) we'll do.
It takes 18 months to double the computational power of microprocessors but it took man thousands of years to invent the zipper. I never really understood that till these days.
Here is a sample of my latest results from Optickle simulations of the locking signal for the Power Recycling Cavity.
Thanks also to Rob's revolutionary bidimensional rotating matrix idea (I can see entire books of linear algebra going to be rewritten now because of that) I could find the way to determine the optimal demodulation phases for the demod signals.
There were also an other couple of missing details. But that came easily along.
The parfor function for the parallel computation in Matlab sped up some loops by a factor of 100.
In these particular plots there's still no CARM offset scan. That's what I'm going to post next on the elog, together with the signals for the other degrees of freedom.
Just to show that I'm confident I'm getting reasonable results, I'll post two PRC scans for different CARM. One set of plots is for the current 40m with -19.78 deg of SRM detuning phase, the other is for the Old Upgrade (9 Mhz vs the 11 currently planned) with no detuning phase.
I'm going to put together the results and get some conclusion about the 3f locking scheme for the current 40m and the upgrade.
Today we found the green beam from the end was totally missing at the vertex.
- What we found was very weak green beam at the end. Unhappy.
- We removed the PBS. We should obtain the beam for the fiber from the rejection of the (sort of) dichroic separator although the given space is not large.
- The temperature controller was off. We turned it on again.
- We found everything was still misaligned. Aligned the crystal, aligned the Faraday for the green.
- Aligned the last two steering mirrors such that we hit the approximate center of the ETMX and the center of the ITMX.
- Made the fine alignment to have the green beam at the PSL table.
The green beam emerged from the chamber looks not so round as there is a clipping at an in-vac steering.
We will make the thorough realignment before closing the tank.
We extracted the fiber that Suresh and Sonali laid over the summer, for the IR beat for the Ygreen laser, and Frank took it back to Bridge to be used in the new fiber distributed reference laser setup.
In light of the Yend auxiliary laser's ill health, I think we should reconsider the possibility of changing out the Yend laser table next week.
My thinking here is that if whatever the new mode matching solution is for a replacement laser (Tara has borrowed our spare NPRO that used to sit on top of the fridge, or we could take Annalisa's) requires a rework of the table layout, we might as well put the new layout onto the new table. So, we need to figure out what laser we will put in as the new Ygreen, and what it's waist looks like. If it just requires a small movement of existing lenses or new lenses in similar positions to the current ones, we can keep living with our current table. But, if the mode matching solution requires enough changes to distances / lens placement / whatever, we should think seriously about putting in the new table next week.
Here's what I would like to see happen on / before Monday:
Annalisa - Mode matching solution for new laser. If we get the laser back from Tara, this will involve first measuring the waist, otherwise we already know the waist of the ABSL laser that Annalisa is currently using.
Annalisa and Steve - Find optics for new mode matching in the lab, or order them by Monday afternoon.
Manasa - List of every screw, washer, optic, mount, etc. that will go on the new Y end table, with a notation as to whether or not we have it in-hand, and if not, what needs to happen before we do. Also, for things that we don't have, I'd like to see a summary of temporary solutions (e.g. keep using current mount for doubling crystal while new one is being machined).
Manasa / Annalisa / Koji - will the new mode matching solution fit within the existing layout, or do we need to redo the table layout?
Zach has just replied, and said that we should feel free to take the laser from his iodine setup in the West Bridge subbasement, in the ATF lab.
Annalisa, please ask Koji or Tara to show you where it is, and help you bring it to the 40m. You should install it (temporarily) on the PSL table, measure the waist, and find the beat in IR. Elog 3755 and elog 3759 have some of the details on how it has been done in the past.
Ok, I'm going to contact Koji.
1) Annalisa is going to start working on mode profiling and beat note search for the old MOPA NPRO.
2) In the meantime, Manasa is working on the end table items. This will be reviewed by KA in the afternoon.
The laser at ATF is moved to the 40m when the status of 1) and 2) is determined by KA to be reasonable.
We also make the beat note measurement for the ATF laser too.
We also make the beat note measurement for the ATF laser too.
Today I installed mirrors to steer the pick-off from the main laser beam in a more free part of the PSL table and make the beat note measurement between it and the NPRO.
At the beginning I took the beam from the harmonic separator after the doubling crystal, and I was going to bring it in a less full part of the table . At the end I realized that there was already a beam steered up to a more free part of the table, and the beam is taken from the transmission of the PMC.
Tomorrow I'm going to use that beam to find the beat note with the NPRO.
I also removed almost all the steering optics that I used on the ITMY table to send the auxiliary beam for ABSL through the window parallel to the POY beam. The most important thing is that I removed the BS, which was on the same path of the POY beam (see elog 8257).
I moved the auxiliary laser from the ITMY table to the PSL table and installed all the optics (mirrors and lenses) to steer the beam up to a PDA55 photodiode, where also the pick-off of the PSL is sent.
Tomorrow I'm going to measure the beat note between the two.
[Koji, Annalisa, Manasa]
NPRO with controller from ATF joins the 40m. We have put it on the POY table where we plan to use it for ABSL.
The beat note between the main PSL and the auxiliarly NPRO has been found!
The setup didn't change with respect to the one described on the previous note on the elog. A multimeter has been connected to the laser controller diagnostic pin to read out the voltage that indicated the laser crystal temperature.
The connector has been taken from the Yend table laser controller.
The voltage on the multimeter gave the same temperature shown by "Laser temperature" on the display of the controller, while "set temperature" was wrong.
The temperature has been varied using the laser controller with reference to the voltage read on the multimeter display.
Starting from 35.2 °C, the temperature has been first lowered until 20 °C and no beat note has been found, then temperature has been increased up to 35.2 °C and the first beat note has been found at 38.0 °C.
It has been detected at a frequency of about 80 MHz with an RF power of -27 dBm and a frequency fluctuation of about +/- 4 MHz.
I made more measurements slowly varying the laser temperature, to see how the beat note frequency changes with it. I'll make the plot and post it as soon.
I plot the variation of the beat note frequency as a function of "Alberto" NPRO laser's temperature.
After some discussion, now I'm going to vary the PSL temperature and find the auxiliary NPRO temperature matching to have the beat note between the two.
"Alberto"NPRO laser has been moved again on PSL table in order to make a measurement of the beat note varying also the PSL temperature.
It is useful because if the PSL temperature would drift we have to know which is the NPRO temperature that returns the beat.
I'm going to measure it tomorrow.
I measured the beat note between the "Alberto" NPRO laser and the PSL varying the PSL temperature and find the matching NPRO temperature that gave the beat.
I first switched off the FSS loop for the PSL, then I varied its temperature and switched on the loop back.
PSL temperature has been varied starting from 31.88 °C (its starting temperature) down to 23.88 by 1°C step, and then from 31.88 °C up to 36.92 °C, always with a 1°C step.
For each PSL temperature, the NPRO temperature was varied as well, in way to find the temperature to have a beat note between the two.
The trend of the NPRO laser temperature reminds the frequency change of the laser as a function of the crystal temperature continuous tuning.
I made measurements only for the first temperature of the NPRO laser which gave me the beat note. Tomorrow I'm going to find the beat note also for higher frequencies of the NPRO laser.
The beat note between the PSL laser and the "Alberto" NPRO laser has been measured. In particular, for each PSL temperature, more than one Aux laser frequency has been found.
The second of the three curves seems to be more stable than the other two, even if a "step" trend can be found in all of them (maybe due to the frequency change of the NPRO laser as a function of the crystal temperature continuous tuning, as mentioned in the previous elog). This is the reason why the points are not perfectly aligned, and the errors on the fit parameters are so big.
We replaced the MC Refl path BS with the Y1, as usual, so that the full ~100mW goes to the REFL PD, so we don't have WFS or MC refl camera.
The MC spots were all outside of 1mm, and some were beyond 2mm (for MC1,3, P,Y....MC2 is of course free since we have more DoFs than we need), so we touched (very, very slightly) the zigzag mirrors on the PSL table. We realigned the MC, and now the spots are centered to my satisfaction.
MC1,2,3 Pit, MC1,2,3 Yaw (in mm):
[0.46444020918749457, 8.2634316545130009, -0.41417975237831089, -0.89401481457980592, -0.9323196976382162, -1.543145765853893]
MC2 is way off in pitch, according to this measurement, and it's been consistently going down as we move the MC2 spot in the same direction (up on the monitor), but since we started at +15mm and are now at +8, and we've gone quite a ways, I'm not sure that we really want to go all the way to 0. Anyhow, MC1 and MC3 are the ones which define our input pointing, so we're quitting for tonight.
We will turn on the PZTs and begin with the official vent list for dummies tomorrow.
We went into the vertex today to see about fixing the alignment. The in-air access connector is in place, and we took heavy doors off of BS, ITMY, and ETMY chambers.
We started by looking at the pointing from the PZTs. Manasa and Raji hooked up HV power supplies to the PZTs and set them to the middle of their ranges (75 V).
We installed a target on the BS cage, and new "free standing" targets made special by Steve for the SOSs on ITMY and ETMY.
Using a free-standing aperture target we looked at the beam height before PZT2. It was a little high, so we adjusted it with PZT1. Once that was done we looked at the beam height at PR2, and adjusted that height with PZT1.
We then tried to use the hysteresis in PR2 to adjust the beam height at ITMY. Pushing just a little bit at the top or bottom of PR2 would repoint the beam in pitch. This sort of works, but it's stupid. Using this method we got the beam more or less centered vertically at ITMY.
We moved on to ETMY with the idea that we would again use the hysteresis in PR3 to get the vertical pointing to the ETM correct. This was a good demonstration of just how stupid the tip-tilts really are. Just touching slightly at the top or bottom or PR3 we could completely change the pointing at ETMY, by mili-radians (~4 cm over 40m).
At this point I cried foul. This is not an acceptable situation. Very little stimulation to the tip-tilts can repoint the beam inside the PR cavity.
Steve says that the TT weights, which will attach to the base of the TT mirror mounts and should help keep the mirrors vertical and not hysteretic, are being baked now and should be available tomorrow. We therefore decided to stop what we were doing today, since we'll have to just redo it all again tomorrow once the weights are installed.
Manasa and Raji hooked up HV power supplies to the PZTs and set them to the middle of their ranges (75 V).
The high-voltage power supply from the OMC was removed to replace one of the PZT power supplies. The power supply terminals were connected to the rear connection ports as per instructions from the manual (TB1 panel: port 3 - (-)OUT and port7 - (+)OUT). They were both switched on and set to deliver (75V) to the PZTs.
Steve says that the TT weights, which will attach to the base of the TT mirror mounts and should help keep the mirrors vertical and not hysteretic, are being baked now and should be available tomorrow.
We also wrote down the serial numbers (top center of each TT, inscribed by hand) for what tip tilt is installed where. I then went through the elog to determine which TT was suspended with what kind of wire (thick or thin). Summary: all installed tip tilts have thick wire, 0.0036" diameter.
As noted in elog 3295, we had found that there was similar hysteresis whether we used the thick or the thin wire, so we had decided not to go back and re-suspend every optic.
Also, since we will redo the pitch balance tomorrow with the new hardware tomorrow, I think we should put in the new LaserOptik mirrors at the same time. We have not yet gotten phase maps of them, but we might as well do this rebalancing once, rather than twice.
This means that the low voltage dual supply which was wired in series (so could supply a max of 63V = 2*31.5V) has been replaced with the OMC power supply. This is okay since we haven't turned on the OMC PZTs in a long, long time. This is *not* the power supply for the output pointing PZTs. When she says "both", she means the new HV supply, as well as the HV supply that was already there, so both pitch and yaw for PZT2 are being supplied with 75V now.
Jamie has arranged for phase map measurements this afternoon, so I will take the 6 dichroic LaserOptik optics over to Downs at 1:15 this afternoon.
Team Jamie+Nic will lead the effort to clamp down dog clamps as placement markers for all 4 in-vac passive TTs, and then pull all 4 TTs out of the chambers. They plus Den will move the TTs to the Cleanroom, and will start to install the new pitch alignment hardware.
When I return with the optics, we will install them in the TTs and re-balance them. Then we can put them back in the chambers and get back to work on alignment.
After we re-install the TTs, we will need to check the leveling of all 3 corner tables, just to be sure.
Raji took the optics over. They were all measured at 0 deg incidence angle, although we will use them at the angles required for the recycling folding mirrors. Here's the summary from GariLynn:
In general all six pieces have a radius of curvature of around -700 meters.
I measured the transmitted power @1064nm on one of the LaserOptik mirrors labled SN6
Here is the data
The mirror is not a good reflector at 0 deg.
After lunch we began where Raji and Jamie had left things. PR2 was unfortunately pitched down so far that it was almost hitting the table just in front of PR3. I loosened the 4 clamp screws that hold the wire clamp assembly to the mirror holder, and tapped it back and forth until I was within hysteresis range, re-tightened, then tapped the top and bottom until we were at the correct beam height just in front of PR3. I also had to unclamp it from the table and twist the base a tiny bit, since the beam was closer to hitting the beam tube than the optic. Finally, however, PR2 is adjusted such that the beam hits the center of PR3.
Moving on to PR3, the pitch looked good while we were looking at the aperture placed near the face of ITMY, so we left that alone. The beam is off in yaw though. Several times I unclamped the tip tilt from the table, and twisted it one way or another, but every time when I tighten the dog clamps, I'm too far off in yaw. The beam points a little too far south of the center of ITMY, so we were putting the beam a little north of the center before I clamped it, but even tightening the screws in the same order, by the same amount each time, causes a different amount of slipping/twisting/something of the TT mount, so we never end up directly in the center of the ITM. It seems a little like a stochastic process, and we just need to do it a few more times until we get it right.
We left it clamped to the table, but not in it's final place, and left for JClub. On Monday morning we need to go back to it. As long as we're pretty close to centered, we should probably also have someone at ETMY checking the centering, because we need to be centered in both ITMY and ETMY.
We have not touched the SR tip tilts, so those will obviously need some attention when we get to that point.