On Friday, Koji and I adjusted the beam pointing into the DRMI using the PZT yaw and found that the beam inside the DRMI (as seen on the AS camera) looked OK (not distorted too much).
So it seems that the issue seen before, namely that the DRMI resonant mode is very strange, is no longer true.
The camera image at the AS port still looks elliptical. So Jenne and Mike have started to make this beam round by adjusting the lenses.
Our plan now is:
1) Fix AS camera optics to get a round beam (single bounce off of ITMY).
2) Flash DRMI to make sure the beam at AS is still round.
3) Using the moveable Watec camera and Sensoray, get images of the spot on all DRMI mirrors with DRMI flashing. Use targets and rulers whenever possible to get quantitative measurements of the beam positions. (i.e. just saying "Oh, its pretty much in the center" is the Mickey Mouse approach to science)
4) Align all pickoff beams in this situation. Make sure there is no in vac clipping. Align IP POS and ANG using this input beam pointing.
5) Pump down.
Summary: Recorded the presence of higher order modes in IMC
What I did: Misaligned the flat mirror MC1 by small amount in both pitch and yaw (it was needed to be done cause at the beginning of the experiment no higher order modes were present) and scanned the cavity for frequency-range 32MHz to 45MHz.
I found the presence of higher order modes around 36.7MHz (1st order) and 40.6MHz (2nd order) along with two other strong modes near 35MHz and 42.5MHz.
Please, restore condition after you finished and update elog right away! People wasted hours yesterday not knowing the condition of the MC
We need to do the following things: Images of optics in DRMI chain, place black glass beam dumps, make sure pickoff beams get out, align IP POS/ANG.
Black glass: behind MMT1, behind IPPOSSM3, forward-going POP beam.
Images and pickoff stuff should happen at the end of each vent.
Images need to be taken of the following optics (with ruler edge at center of optic):
* BS (front and back?)
* Viewport as AS beam leaves chamber
* POYM1 (check no clipping on edge of mount)
* POXM1 (check no clipping on edge of mount)
Pickoff / aux beams:
* REFL path
We aligned the DRMI, and have concluded that it looks good enough that we should close up and pump down soon. We still need to use the camera to check things, and get all pickoff beams out of the chambers, so don't get too excited yet.
We looked at the mode matching telescope's calculated beam propagation, and since we're using spherical telescope mirrors at non-zero degree incidence angle, we expect an astigmatism about like what we are seeing on the AS camera. This matches up with the measurements that Mike posted from his and Q's measurements earlier today. We think that it has 'always' been this way, and someone just picked a camera position such that the beam used to look more round than it does now.
We aren't entirely sure what's up with the SRM - it almost looks like the pitch and yaw are coupled, but it was pretty easy to align the PRMI. We don't see any evidence of the crazy, crappy beam that we did before the vent. This means we have fixed most of the bad clipping problems we were seeing over the last ~year.
In the process of aligning the DRMI, we fixed up the input beam alignment - we were not hitting the exact centers of the MMT mirrors (in pitch, mostly), so we fixed that, and propagated the alignment fix through the chain. In all, we touched the knobs on PZT1, MMT1, MMT2, PZT2. The beam then went through the SRM, and we touched a few of the output steering mirrors to get the beam centered on all mirrors.
I remeasured the MC spot positions, and they're a little worse than they have been. Some of the spots seem to be off by 1.75mm (or less) on MC 1 and 3. The numbers, MC1,2,3 pitch, then MC1,2,3 yaw are: 1.749759 9.744013 1.025681 -0.791683 -1.338786 -1.779958
A question to consider before doing the final-final alignment checking is: do we need to get the MC spots centered better than this, especially in light of the potential PMC axis having moved?
After much fussing, we got a picture of MMT1 with the beam.
Using the iris doesn't seem feasible. Since it has to be significantly separated from the optic, it is hard to judge whether it is centered, especially in yaw.
It took ~30 min to get this picture. Comments on whether this kind of picture is good enough are welcomed, since there are many more to be taken.
I've been taking more photos. Obviously, it gets quicker as I go along and get the hang of it. Also, I've been taking overhead pictures with the Nikon so we can see what kind of parallax there is for each snapshot.
However, I just took MMT2, and the beam is nearly falling off the side of the optic! It seemed fine last night when Rana and I were working on it. The MC spots haven't moved significantly (I had measured yesterday, and again a few hours ago). WTF?
This means that I need to move the knobs of MMT1, and then redo the whole alignment chain all over again. Lame.
EDIT: MC spot positions, last night at 12:33am, and this afternoon at 2:12pm:
year month day hour minute MC1pit MC2pit MC3pit MC1yaw MC2yaw MC3yaw
./data_spotMeasurements/MCdecenter201209140033.dat 1.749759 9.744013 1.025681 -0.791683 -1.338786 -1.779958
./data_spotMeasurements/MCdecenter201209141412.dat 1.702974 7.916438 0.986519 -0.888736 -0.170237 -1.771267
All the photos so far:
More photos were taken. Will post Monday, because too hungry now.
Have eaten. Here's a PDF with all the pictures to-date, along with a few notes.
Also, the first thing we did on Saturday was to fix the yaw pointing of MMT1, so that the beam hit the center of MMT2. Then we had to touch PZT2 to compensate. We put the iris target on the BS, and adjusted PZT2 until the beam went nicely through there. The resulting beam looks good on the SRM, and teh beam is still hitting the AS camera.
We took the last of the in-vac photos of mirrors today. I'll post in the morning.
Tomorrow, I'll align the DRMI once more to check, and get IPPOS and IPANG out of the vacuum. I'll take a look at POX, POY and POP, but we may just have to cross our fingers and hope for the best on those ones. They were pretty hard to get out of the vac during their initial alignment, since they're so weak.
Also, tomorrow morning Steve is going to try out our new light access connector!!!! I'm so excited!
The goal is to put heavy doors on, on Wed, and start pumping Wed afternoon / Thurs evening.
My hope is that the DRMI flashes will be bright enough to see on the PO beams. IF we get 10 mW through the Faraday, you should get some buildup when the carrier resonates in the DRMI.
If the recycling gain is 10 and the pickoff fraction is 100 ppm you ought to get ~10 uW on PO. How much of the recycling cavity power gets out of POP?
The photos on the OMC table are particularly tricky, since the camera plus the 'bathroom' mirror add a lot of weight....even if the MC locked, the input beam would be completely different, so all of the beams would be wrong.
During some of the work on the BS table, ITMY was realigned to have its beam retro-reflect, since the weight of the camera plus mirror was shifting all of the suspended optics on the BS table. ITMY was restored after that, for subsequent photos.
I have touched PZT2 such that the beam goes through the 45 degree non-iris target on the beam splitter. This puts the beam at the center of ITMY, and without moving the BS, at the center of ITMX. I say "at the center", but what I really mean is I put the target approximately at the center, within what looks like, say, 2 mm, by looking from above. The target was many (5ish) centimeters away from the optic though, so that's why my side-to-side centering isn't so precise. Given that, the beam was always more than half going through the hole of the target for both ITMs, so I'm claiming that the spots on the ITMs are within a few mm of center.
With this alignment, the beam was also hitting the center of the SRM (with all the same caveats).
I was able to get the SRM to retroreflect, while I still had Michelson fringing, so I think that I had the SRMI at least close to aligned (I was looking at the SRM retroreflection at the beam splitter, not all the way out to the AS port). PRM is also pretty easy to align.
We're hitting the top of the AS camera, so I think things are pretty good. I don't see beam on the REFL camera, but no investigation of that has been done as yet.
There is some scattering going on in the BS / ITMX chambers that's making me kind of unhappy. I don't know how to get this to embed the youtube video, so here's the embed link, as well as the regular link:
youtube of AS and BS/PRM camera.
<iframe width="420" height="315" src="http://www.youtube.com/embed/QUbnMLXSS5U" frameborder="0" allowfullscreen></iframe>
Manasa watched the camera while I waved an IR card around in the BS chamber, and the only way I was able to get all the scatter spots to go away was to either block the beam incident on the BS (duh), or block the beam reflected off the BS, heading to ITMX. Manasa said that the scatter spots still looked like they were fringing though, so I'm confused. I may wave a card around in the ITMX chamber when I come back later tonight, to see what I can see. Also, I just misaligned the SRM, and the scatter spots moved. Now there's just some scatter off of what looks like the BS OSEM holders, as seen through the BS optic.
The DRMI was aligned once again tonight.
Here's a video: http://youtu.be/Cy8nHL9yMeM (Can someone please tell me / remind me how to make the elog embed videos?!?)
Description of video:
Video capture of AS camera.
NOTE: The beam is a few centimeters above ETMY with this alignment, so it will not be final.
Beginning is ITMY only.
ITMX is realigned to form MICH.
PRM is realigned to form PRMI.
SRM is realigned to form DRMI.
PRM is misaligned to form SRMI.
ITMX is misaligned to form SRY.
With this alignment, I opened up the ETMY door to find the beam there. The beam is ~half on, ~half off of the top of the glass baffle. Not the top of the hole, but the top of the piece of glass. This means that it's many centimeters too high at ETMY. This helps explain why, while swinging PZT2 around the other day, I could not see any beam on the cage. It did, however, look pretty close (within a centimeter....I didn't look closer than that since it was so off in pitch) to centered yaw-wise.
Tomorrow I'd like a Clean assistant to help tweak PZT2 to hit the center of ETMY. We'll need to put the 45 degree target back on to make sure that we don't end up pointing funny down the arm. Then I'll realign the DRMI one more time.
Tonight, I can't check the full AS path, or any of the REFL path once it diverges from the main path. Steve's new contraption (which is awesome!) doesn't have doors/windows yet, so I can't open it to get an IR card anywhere near any optics in the IOO or OMC chambers. I waved PRM around a bit, but I can't find the beam on the REFL camera, so I definitely need to check that whole path again before we close up.
So, we're not closing up tomorrow, but progress has been made, and we're getting closer.
Note to self: These are the ITMX, ITMY, PRM, BS, SRM biases with this DRMI alignment. The DRMI is good, but the arms aren't, so these won't be final. The saved alignments are still those with (for the Yarm) the beam bouncing several times between ITMY and ETMY. BS was aligned at the time to hit the center of ETMX, and PRM and SRM should be retro reflecting in that alignment. So, it's possible, that aligning PZT2 to hit the center of ETMY and restoring all of the optics will get me close to being back to DRMI aligned, but in a condition that the arms are align-able too.
I'm making a separate entry to go along with this thread of photos...
Putting the camera and 'bathroom' mirror on any table pretty significantly changes the leveling of any table. The mirror especially is very heavy, although the camera is not feather light. We need to come up with a new plan for taking alignment-confirming photos without adding anything to the tables. That, or we have to level the table between each camera shot. Anyone who has ever leveled one of our in-vac tables should shudder in horror at idea #2, so we need to put some thought into idea #1 before our next vent. Vent Czar - can you put this on the list, in addition to the REFL rearrangement stuff?
As a result of this, PZT2 needed to be reverted to the place it was before work began on Saturday (so that the beam goes through the 45 degree target without any extra stuff on the table). This means, unfortunately, that all of the photos / still captures of optics after PZT2 are invalid.
[Unni, Manasa, Jenne]
It turned out that the beam was a teeny bit high in the corner, so we touched PZT1 and PZT2 knobs to translate the beam down a bit.
Now the beam is centered on the BS (using the 45 degree non-iris target), centered on ETMY (using Steve's latest target, which worked perfectly), and then BS was aligned a tiny bit (really, it didn't need much) to get the beam centered on ETMX.
After dinner I'll align ITMX and ITMY such that their beams retroreflect and I get MICH fringes. I'll also align SRM and PRM to retroreflect. Check no clipping on AS path, get REFL path out, center IPPOS and IPANG, check POX, POY and POP. Then, I think we might be almost done.
Using the alignment of the PZTs and BS from pre-dinner, where the beam was hitting the center of both ETMs, we aligned the DRMI. The beam was off on the SRM in yaw by ~half a beam diameter, so I undid Koji's movement of SR2 from a week ago. I loosened the SR2 dog clamps, touched it gently on the base to do a little bit of angle, then re-clamped it. Once again, Steve's new brass centering target was awesome, since it was on the SRM while I was moving SR2.
We approximately recentered the beam on the AS camera, although it didn't need much once we got the beam out of the vacuum, by centering it on all of the output AS path mirrors.
We also got IPPOS out of the vacuum. Manasa was in the process of centering the QPD when the laptop died from too long being unplugged, so we leave that for tomorrow.
Left to do:
REFL path. REFL is not coming out of the vacuum, and with the light access connector I can't reach any of the REFL steering mirrors, since they're in the center of the IOO table.
IPANG. Should be easy.
POP, POX, POY. Need to the the camera-on-a-stick back down to the corner (from ETMY) and point it at the pickoff mirrors to ensure that beam is getting out of the vacuum.
Steve!! The light access connector got more ripped during the work last night...we've just taped it back. We might need to figure out a better way to do this than just cutting through the cover.
QPD at IPPOS has been centered by removing the filter at the QPD.
So we need to remember to check back on AS camera path and the IPPOS as well in addition to the usual MCrefl path.
P.S. We would be happy to have a new laptop in the lab to replace "Belladonna"!
We think this math is wrong.
If we have P mW through the Faraday, PRM's transmission is 5.5%, BS transmission is 50%, Recycling gain is ~10, pickoff fraction is ~100ppm, we have:
P mW * 5.5e-2 * 0.5 * 10 * 100e-6 = P * 2750e-8 mW = P * 2.7e-5 mW.
So, if P=10 (10mW through the Faraday), we should have 2.7e-4 mW = 2.7e-7 W = 0.27 microwatts = not so many watts.
If P = 100 (100mW through the Faraday), we should have 2.7 microwatts. Still, not so many watts.
We have the Watec pointed at POY right now, DRMI is flashing, I'm waving the IR card in front of the mirror, and Manasa isn't able to see anything on the monitor. The power into the vacuum is 100mW (we just measured and adjusted it), so even if we were getting a full 100mW through the Faraday, it would be hard to see. If we're assuming we get ~half the power through the Faraday, then we should only have 1 microwatt
[Jenne, Unni, Manasa]
I touched some in-vac steering mirrors, so we have REFL and IPANG coming out of the vacuum, not clipping. IPPOS was done yesterday. I re-checked a few optics in the AS path that were hard to see yesterday while the plastic light access connector was in place, and AS still looks good.
Except for POX, POY, POP, and putting the regular EQ stops back on PRM, I think we're done with the in-vac stuff.
We can't mathdo
[Rana, Jenne, Manasa]
POX is coming out of the vacuum. We'll do POY tomorrow. We were able to hold the Watec outside the chamber and focus it on the pickoff mirror, and make sure it was roughly centered. Then we took the lens off the camera, put the camera in the POX beam path, and I steered the pickoff mirror until we were hitting the camera. POY will be done the same way.
POP is more challenging, since the transmission of the G&H mirrors is so low. We're not able to see a beam on an IR card held in the POP beam path. I had thought of removing PR2, getting the beam out, then putting PR2 back (using the same dog clamping some alignment markers technique that we use for the test masses), but the G&H mirrors have a 2 degree wedge, so this won't work. It would be fine for pitch, since the arrow is on the side of the optic, but it wouldn't be correct for yaw.
Maybe we should do something similar to what Suresh et. al. did when they set POP up originally - I think they put a green laser pointer on the POX table, and aligned it such that they were hitting the correct spot on PR2 and PRM (correct = the same as the IR spot, which should be the center of the optics). If we can do that with the POP in-vac steering mirrors, then we're fine, and POP should come out when we're back to high power.
All video capture snapshots of tonights pictures are on the pianosa desktop.
We put a green laser pointer at ~4 inches on the POX table, and steered it using a mirror on the POX table to hit the center of the last in-vac mirror that POP sees. I then steered that mirror so we were hitting the center of the other POP in-vac steering mirror, and hitting the same spot as the main IR beam. It is easy to hold an IR card in front of PR2 and see the IR and green beams simultaneously. I aligned both of the POP in-vac steering mirrors such that the green beam is co-aligned with the IR beam at PR2, as well as as far as I could reach toward the face of PRM from the ITMX door.
Note: The drawings by Koji have the POP "forward" beam (transmission through PR2 of the beam from PRM to PR2) dumped, while the POP "backward" beam (transmission through PR2 of the beam from PR3 to PR2) leaving the vacuum. I aligned the steering mirrors such that the 'forward' beam would come out, although no dump is in place to dump the other beam. I can't think of a reason why we care one way or the other, but I feel like Koji has perhaps mentioned something in the past. I need to figure this out before we put doors on.
Like yesterday with POX, we used the Watec with the aperture fully open to look at the POY pickoff, while I held the IR card in front of the mirror, to confirm that the beam was ~on the center of the optic. Then we took the lens off the camera, and made sure that the POY beam hit the CCD on the POY table.
To do list for Monday: While we are putting the heavy doors on, someone needs to wave an IR card in front of the IPANG steering mirrors in the ETMY chamber, while someone else takes a photo / still snapshot with the Watec. Also, Manasa wanted to retake in-vac photos of at least the ITMY chamber, since SR2 was moved a very slight amount. Also, also, someone tall needs to put the regular EQ stops on the PRM face (we have the old spring ones in there now).
Before pumpdown, we also need to get the IPANG beam centered on the PD. The beam is cleanly coming out of the vacuum and hitting the first out of vac steering mirror, I just haven't centered it onto the QPD.
Barring any other thoughts that people have of things that *must* be done before we pump down, I think we're ready to start putting heavy doors on the chambers on Monday.
Other thoughts, for next vent: We need to re-look at the ITMY table. POY's pickoff is just too close to the main beam. Is it possible to move the AS steering mirrors and get POY from the BS table? VENT CZAR: please put looking at this on the next vent to-do list.
Unaltered PR2 images, with IR card, without card, and steering mirror:
Unaltered POX and POY images:
The POX images only needed a major brightness reduction and increased contrast to view:
The POY images needed their intensity histograms shifted slightly right and made left-tailed:
The SP table was found open this morning. Please, do not make optics dirty!
I cleaned up the tops of the SP table.
Stop storing your junk, boxes, laptops, etc. on the optical tables. This includes the big SP table. Please move all of that junk into racks or shelves, etc.
What was the reasoning / resolution of the POP forward/backward beam? Are we going to have the right beam for DRMI locking?
From Koji's email to me:
"With the backward beam you can see the returning beam even when the PRM is misaligned. That's the only difference. Once the PRM is aligned both beams have the same information."
So, we should be fine.
There had to be a power outage. Laser and air condition turned back on. The vacuum is OK
Sorensen DC power supplies were tripped, so they were reset: at AUX OMC South 18V and 28V for RF PS and at 1X1 24V
Power Outage confirmed:
** Notification **
CALIFORNIA INSTITUTE OF TECHNOLOGY
Date: Thursday October 04,2012
This morning at 2:17 a.m. much of the City of Pasadena including our Campus experienced a electric power sag of short duration, approximately 1/10 of a second. The cause was a fault on one of Pasadena’s 17KV circuits. Some sensitive equipment have been impacted.
Contact: Mike Anchondo x-4999
40 plus freshmen visited the 40m today
I started to create a Finesse model of the PRC cavity. We have the phase maps for the PRC and the two ITMs. I could not find anything for PR2,3 and BS. All files can be found in my SVN folder /janosch/PRC40m. I used the AutoCAD model to determine angles of incidence and distances. These numbers are largely inconsistent with numbers that you can find elsewhere on the 40m wiki, but this certainly depends on what accuracy is required for interferometer alignment and I don't understand anything about alignment.
The phase maps come in a format that needs to be modified before they can be used in Finesse. I have started with this work, but maybe someone else can take over. The phase maps show tilts and the PRC also has the curvature. These have to be subtracted out before the maps can be loaded into Finesse. I asked GariLynn for the code that they use. The Finesse model (MichPRC_40m.kat) does not load the phasemaps yet, and I just wrote some random parameter values for the TEM00 input beam to the PRC. So these Gauss parameters need to be corrected.
I will only go on with this work if Rana tells me that I should do so, otherwise it is on hold until we have a volunteer.
Just some plots. There is nothing new here except for the fact that I learned how to analyze phase maps myself and how to prepare them for Finesse. In other words, everything is ready for a Finesse simulation.
These phase maps show the raw measurement of ITMY, ITMX and PRC:
Subtracting out the tilt from all phase maps, and the curvature from the PRC (I found the fit 121m consistent with previous fits), the one obtains the following residuals that can be used in Finesse (order is again ITMY, ITMX and PRC):
[Koji / Kiwamu]
We have realigned the interferometer except the incident beam.
The REFL beam is not coming out from the chamber and is likely hitting the holder of a mirror in the OMC chamber.
So we need to open the chamber again before trying to lock the recycled interferometers at some point.
--- What we did
---- things to be fixed
- Align the steering mirrors in the faraday rejected beam path (requires vent)
- SRM oplev (this is out of the QPD range)
- ITMX oplev (out of the range too)
We're discussing the plan for the next vent. Now that we have all the tip-tilt stuff in hand, we should get ready for the big TT installation vent ASAP. The question is what remains to be done, and when can we be ready
Stuff that needs doing:
* characterize TTs, check electrical connection of quadrupus cables, bake cables and base plates - a week or so (not including baking)
* phase map of LaserOptik mirrors (decide on needed resolution) - a week or so?
* get ready to swap G&H mirrors with LaserOptik mirrors (PR2, PR3, SR2, SR3)
* assembly of black glass beam dumps - one afternoon
* green periscope moving - day or so to make sure greens are resonant in arms, so we have something to align to
* redraw of REFL path?? (rotate 2nd refl mirror to reflect beam to the east, then add mirror to get beam out of IOO chamber viewport), cut hole in BS oplev table's box, install black beam tube
* FI camera mount - make sure it's here, baked
* active TT pitch damping plan
* passive TT weight addition and pitch alignment plan
* camera plan for taking in-chamber photos without touching the tables
* look at layout of ITMY table. POY pick-off too close to main beam. Can we move POY pick-off to BS table?
* remount black glass baffles on SOS cages.
Stuff to bake:
* Quadrupus cables
* TT base plates
* FI mirror mount for FI camera
* stuff to add to active TTs
* stuff to add to passive TTs
I see 4+ possible paths for us to take, in terms of a possible vent in the next few weeks:
No Vent - Just do FPPRMI, using AS55
Mini Vent - Fix REFL path, nothing else. ~1 day at atmosphere
Medium Vent - Fix REFL path, swap G&H mirrors for LaserOptik mirrors (so also resuspend passive TTs, maybe add pitch adjustment option). ~1 week or so at atmosphere - do this rather than Mini if Jan's Finesse calc says the G&H mirrors are too rough
Mega Vent - Fix all the things, do all the things. Long time at atmosphere
The "+" is to take into account all the possible variations on "medium vent". The No, Mini and Medium options assume we'll do the Mega option later, just not immediately.
ETMX optical table was left open. Burned toast award goes to ......?
Now that I read Koji's last elog about phase maps, I am not sure if these are still required, but here they are (the tilt-removed phase maps of the Laser Optik mirrors), first 1, 2, 3:
So they all have an elevated center. I am not sure why the phase maps of mirrors 5 and 6 are slightly smaller in dimension. Anyhow, all mirrors have quite strong aberrations. Also, there is no big difference between the mirrors. Check for yourself, but be careful with the colors since the scales are all different.
Are these maps drawn from the data we extracted using Image SXM??
Indeed. So the only manipulation that I did was to remove the tilt (since this should usually be seen as an artifact of the measurement, or better, we can assume that tilt is compensated by alignment). I did not remove the curvature.
Below are phasemaps for the tip-tilts with both tilt and RoC removed. We have not used Koji's code; but tweaked the earlier code to remove curvature.
The RoC values matched approximately to that quoted by Gari Lynn ~700m.
The color scale for height are not the same for all mirrors.
SN1, SN2 and SN3
SN4, SN5 and SN6
Below are phasemaps for the tip-tilts with both tilt and RoC removed. We have not used Koji's code; but tweaked the earlier code to remove curvature.
The posted residual phase maps show circular contours since the data came with relatively low resolution in height. This is ok for what we want to do with these phase maps (i.e. simulating higher-order mode content in the PRC using Finesse). Better resolution is only required if you want to understand in detail optical scattering out of the cavity. Anyhow, the circular artifacts can be removed by first interpolating the phase maps to a higher lateral resolution, and then performing tilt and curvature subtraction. So we will soon have better looking phase maps posted. Then we should think about what type of Finesse simulation we could run. Certainly one simulation is to look at the beam shape in the PRC, but more interesting could be how sensitive the shape is to mirror alignments. The current simulation shows a mode that resembles the TEM01, but I have not yet tried to find optimal alignment of the mirrors (in simulation) to search for the TEM00 mode.
Suprema- SS clear edge mirror mount 2" diameter is modified for 40m vacuum use. One left and one right handed one. It's adjustment screw housing is bronze! It is not ideal for out gassing.
It will be baked and scanned. If it passes we should use it.
We may need these to bring out some pick-off beams.
I vote against it. We don't know about the grease inside the screw bushings - scans are not everything if adjusting the screw loosens up the grease. If we need more pick off mirrors lets just make some of the kind that we already use inside for the 2" optics.
I think Steve had these prepared in response to my question a few days ago of how badly do we need adjustability for the POX/POY mirrors? We already have cleaned open-sided mounts that have no adjustment screws. So as long as the beam reflects off the ITMs horizontally (which it should), we can do yaw adjustment by twisting the whole mount. We don't need super fine yaw adjustment, we just need to get the beam out, so this is probably good enough.
We should put the POY mirror on this open-sided mount (the one without screws) some time. Perhaps even today.
The hex adjustment screw is removed from the brass bushing for degreasing, cleaning and baking. Newport says the bushing is is brass not bronze.
Brass outgassing rate is 10x higher than copper that is truth. The surface area is small so Krytox grease is ok if it is really needed in the 40m. ( It was ok in the past and it is still there )
Link to the new 40m DCC Document Tree: E1200979
After a brief look this morning, I called it and declared that we were ok to close up. The access connector is almost all buttoned up, and both ETM doors are on.
Basically nothing moved since last night, which is good. Jenne and I were a little bit worried about how the input pointing might have been effected by our moving of the green periscope in the MC chamber.
First thing this morning I went into the BS chamber to check out the alignment situation there. I put the targets on the PRM and BS cages. We were basically clear through the PRM aperture, and in retro-reflection.
The BS was not quite so clear. There is a little bit of clipping through the exit aperture on the X arm side. However, it didn't seem to me like it was enough to warrant retouching all the input alignment again, as that would have set us back another couple of days at least.
Both arm green beams are cleaning coming out, and are nicely overlapping with the IR beams at the BS (we even have a clean ~04 mode from the Y arm). The AS and REFL spots look good. IPANG and IPPOS are centered and haven't moved much since last night. We're ready to go.
The rest of the vertex doors will go on after lunch.
Jamie and Steve got the ETM doors on this morning.
We got the other heavy doors including the ITMs, BS and the access connector in place.
If nobody raises any concerns in reply to this elog, Steve will assume it as a green signal and will start pumping down first thing Monday morning after the final check on the access connector bellow screws.
Ayaka and I got the ITMY and BS door closed at 45foot pounds just now.
New Lumitek IR Sensor Cards are here. We got 2 pieces of Q-11-T (2" x 2"), 2 pieces of Q-11-T (0.75" x 0.75") and one Q-11 (4" x 5")