The BS and the PRM have 3.3 Hz resonant gain filters that kill the phase margins.
Oplev transfer functions PIT UGF were optimized to be at 2-3 Hz with 60 degree minimum phase margin by adjuting oplev gains.
Additional Notes by KI:
Koji, Rana and Steve
The floor preparation continued today. The really messy part of drilling and jack-hammering the concrete were done in controlled manner.
Particle counts peaked at 106K of 0.3 micron and 13 K of 1.0 micron particles/ cfmin at the top of SP table.
Legs were installed with the help of Koji and strongman Rana. Professor Rana was very useful lifting the 85 lbs legs.
Atm1, Drilling holes for ribbed bar reinforcement of concrete
Atm2, Koji and Rana are playing hide and seek while installing legs
Atm3-4, 6 Rigid tripod legs attached by 6x3 of 1/4-20x 7/8 screws. The top plates of the legs were torqued to 108 ft/lbs by Rana
Craig, Gautam and Steve,
Single mode fiber 50m long is layed out into cable tray that is attached to the beam tube of the Y arm.
It goes from ETMY to PSL enclosure. It is protected at both ends with " clear- nylon slit corrugated loom tubing " 1.5" ID
The fiber is not protected between 1Y1 and 1Y4
Installed 0.5" ID 10 ft long protective tubing at the PSL end of the ETMY fiber this morning. Here I had to cable tie a bunch of cables at the east side of the PSL enclosure.
They were hanging off the table blocking space were the sliding doors move.
At the ETMX end of the X-arm fiber received the same protective tubing.
Crane balancing at the south end is continuing today.
The control room temp is warmer than usual. The heat exchanger Office Pro 18 set point was lowered from 70 to 68F yesterday.
The MOPA headtemp is higher also. The Neslab chiller bath temp peaks around 21.6 C daily. This should be rock solid 20.00 C
It did not have any effect.
Now, I have just lowered the thermostat setting of room 101 from 73 to71F I hope Koji can take this.
Little change in the AC set temp can make wonders. Neslab chiller bath temp 19.99C is back to normal and daily variation of PSL are much better.
Hi Steve -
I found the doc I was looking for:
Specifically, you might find guidance in Section 5 and the pictures at the end of the doc. This should work for Vacseal as well.
Good luck - it will take some time (hours to day or 2)...
I'll be interested to know how it goes.
GariLynn helped us develop this procedure so you could also ask her to cast an eye over the setup if you are worried.
ps: there is no existing fixture to hold SOS optic while soaking it
Proposed Acetone soak dish for SOS epoxy softening.
It has good acces through 5" top ID. The set up is stable and teflon lined.
Materials: glass jar with SS cover, teflon bricks, 0.008" teflon wrapped "high density Drever bricks" and aluminum
Drever brick: I beleive it is a Tungsten alloy. We used it as vac-bat savor at the coffe can. It has high density, heavy and hard, it was never identified.
I will soak one brick to see if it has any reaction ability with acetone.
NO means that only Glass and Teflon can be used for this fixture in Acetone. We can not take a chance on the coating!
I guess the small surface area Aluminum dumbbell, guide rod and-or wire standoff, magnet and epoxy does not degrade the acetone such way that it effects our coating.
Not ot mention, that only the very edge of the coating would in this solution.
Glass soaking dish with teflon guides.
The floor was cleaned under the east arm tube with hand held wet towel. We moved staff around and mopped. I did at the bottom of rack 1Y1, 2 and 3.
Last week we did the south arm tube floor.
Next week we 'd like to clean under rack 1X1,2,3, 4, 5, 6 and 7
1Y4, 1X1,2,3,4 & 5 instrument racks floor space were cleaned.
1X6, 1X7 and 1X9 instrument racks floor space were cleaned today
The wood exteier walls, gutters and doors were painted at CES-Annex building #69
The east and south end of the 40m emergency exit doors are sealed- tapped off temporarily. They will be painted on the out side only. This job will be done by tomorrow noon
Do not open chamber if you smell the paint !
Building: Central Engineering Services
Date: Monday, 04/10/17
Time: 7:00 AM TO 9:00 AM
Notification: Crane Activity
Contact: Ben Smith, X-4190 Brad Nielsen, X-8751
Contractors will be removing the large vaporizer located on the South
side of CES. Vehicle access will be restricted due to crane placement
and operation, but there will be a single traffic lane available. This
work may create minor noise and vibrations.
The PSL out 2" OD beam guide tube was cut 1.5" shorter to 13.5"
The 10" OD 0.25" wall Al tube was replaced by a lighter, not anodized and thinner wall 0.094" tube of 15.5" lenght, that is 0.75" shorter.
The new position of the PSL table made these cuts necessary.
It is posted at the 40m wiki with Gautam' help. Printed copies posted around doors also.
~Vancuver, Canada earthquakes: magnitude 6, 5 and more shaking
No obvious sign of damage.
I powered down 1Y1 and 1Y2 instrument racks of MC and RF-systems this morning.
Both racks, SP table, clean tools-parts boxes and MC2 area are also covered with plastics.
Bertin Bros. Construction, Inc is working on the floor preparation. Their head man is Robby Bertin, cell 626. 831.2264
remove tiles, clean off tile glue, drill for ribbed steel bars, rough clean- surface for good bounding. paint floor with bounding agent
The south end door leaky weather seals replaced.
The aim is here to get some overpressure inside / outside so the lab partical count would not depend on outside condition.
All 3 cranes inspected by professional and load tested with 450 lbs at max reach.
Our 3 cranes passed professional inspection. Fred Goodbar of Konacrane with 450 lbs load at full extension.
Certificates will be posted in 40m wiki as they arrive.
All 3 cranes inspected by professional Fred Goodbar of Konecranes and load tested with 450 lbs at max reach on Friday, March 3, 2017
The horizontal trolley drive stopped working at the east end this morning. It is working intermittently. In the worst case we can take the door off with the manual -Genie- lift.
I'm working with Konecrane to solve the wormgear drive problem.
New gear box installed and tested by Fred KoneCranes.
The 4th week of no wet mopping of the floor and no wet wiping the vacuum envelope.
We cleaned the intakes of the south arm IFO air condition. The bottom duct have quite a bit accumulation Atm1
See wet wiped contrast on Atm2
We found 3 holes around pipes ( coming from CES ) on the east wall that has to be sealed.
After closer examination of these holes, they are sealed off well.
Air condition maintenance will be finished by 11:30am tomorrow.
Yesterday, Kelvin mopped with chemicals the whole floor area of the lab. This was triggered by some visiting ants at our PSL last week. It was 6 months since we had the last fully wet mopped IFO floor.
The cleaning- mopping water became very dirty at the end.
These old specs are not so bad. But we now want to get replacements for the TRX and TRY and PSL viewports that are R <0.1% at 532 and 1064 nm.
I don't know of any issues with keeping BK-7 as the substrate.
Tilted viewports installed in horizontal position. Atm2
New optical quality BK-7 windows in 2001 [4 substrates ] AR coated R<0.75 % for 630-1064nm " Azury BLue" broadband : TRX, TRY, ITMY-Oplev & ITMX-Oplev viewports.
The BS-Oplev and PRM-Oplev 10" CF with 5.38" diameter view was coated the same way. The window here is Corning 7056 Borosilicate
5 more BK-7 substrates were coated R <0.1% of 1064 nm "Golden Orange" Their location: IMC-IN, IFO-REF and OMC The next vent we have to confirm optical quality window locations.
All other conflat flange viewports are 7056 Kovar sealed .
Technical notes of 2001 40m upgrade can be seen at LIGO-T010115- 00- R ....page 14
The microscope shipped back to the vendor for credit yesterday.
http://www.amscope.com/3-5x-180x-boom-stand-trinocular-zoom-stereo-microscope-with-144-led-ring-light-and-10mp-camera.html will be ordered today.
The actual unit we are getting has lockable zoom for better repeatability after calibration: SM-3NTPZZ-144
This AmScope microscope would have 3.5x-180x magnification, calibratable measurement function, 5MP picture and good working distance to work on printed circuit boards.
I've used a Y1 mirror to steer the Y transmission to an R98% BS. The reflected beam falls on PDA520 and the transmitted beam is steered to the camera. The earlier normalization of TRY is no more valid as the power distribution at the PD has changed.
To take this into account, last night, I reduced the TRY gain by a factor of 2. This is not exactly correct - when the layout is finalized we need to figure out what the pickoff situation used to be (we think, based on the Xend, that it could have been 0.5*0.9), and do the correct normalization.
And (2) P140021 “Final Report: Automated Photodiode Frequency Response Measurement System for 40m Lab” by Nichin Sreekantaswamy and also as part of Nichin’s report by there is an archive of data at https://wiki-40m.ligo.caltech.edu/Electronics/PDFR%20system
I made a visual inspection of the system and saw that the following fibers collimators are still mounted in alignment mounts and the fiber is attached and pointed at a photodetector but possibly not aligned.
Photodetector Label Fiber Label
REFL11 REFL55 Fiber on mount
REFL33 REFL33 Fiber on mount
REFL55 REFL11 Fiber on mount
REFL165 No Fiber
AS55 AS55 Fiber on mount
MCREFPD MCREFPD Fiber on mount
No PD Loose unlabeled Fiber No mount
ITMX Optics Table
POX11 POX11 on mount
Unlabeled PD POP22/POP110 on mount
NO PD POP55 loose fiber No mount
The RF switch seems to be hooked up and there is a fiber running from the Diode Laser module to the fiber splitter module. So REFL 11 and REFL545 seem to be illuminated by the wrong fiber. I’ll try and run the software on Monday and check to see if I need to move the fibers or just relabel them.
Batteries replaced in control room UPS after 3 years from replaceUPSbattery.com
Replaced the batteries successfully in the control room. We just had to switch the clips from the old batteries to the new one, which we didn't know was possible until now.
[Koji, Steve, Den]
TT alignment is fine, yaw damping is satisfactory, pitch damping is slow. We might want to add magnets to the mirror and attach blades to the frame for pitch edge current damping.
We are moving towards electronics testing.
Atm1, TT 1.5" high adaptor base will be back from the shop in 10 days.
Atm2, There is no PITCH damping, YAW edie current damping works well at 0.5 mm gap
Atm3, Adjustable Al -disc that contains a small magnet is purely designed.
We have to come up with a solution to have damping in PITCH
Pitch damping solution needed! It should be in the machine shop already.
Measurements for good fit were made. The new shelf will be installed on next Tuesday at 2pm
The reference cavity ion pump is in the way so the cavity will be moved 5" westward. The shelf height space will be 10" Under shelf working height 18" to optical table.
I have just received the scheduling of the PSL self work for tomorrow. Gautam and I agreed that if it is needed I will shut the laser off and cover the hole table with plastic.
While moving the RefCav to facilitate the PSL shelf install, I bumped the power cable to the AOM driver. I will re-solder it in the evening after the shelf installation. PMC and IMC have been re-locked. Judging by the PMC refl camera image, I may also have bumped the camera as the REFL spot is now a little shifted. The fact that the IMC re-locked readily suggests that the input pointing can't have changed significantly because of the RefCav move.
Johannes informed me that he touched up the PMC REFL camera alignment. I am holding off on re-soldering the AOM driver power as I could use another pair of hands getting the power cable disentangled and removed from the 1X2 rack rails, so that I can bring it out to the lab and solder it back on.
Is anyone aware of a more robust connector solution for the type of power pins we have on the AOM driver?
ETMX sus damping recovered. PSL enclousure is dusty at 20V rotation speed. Rainy days as outside condition.
The MET#1 particle counter was moved from CES wall at ITMX to PSL enclousure south west corner at 11am.
The HEPA filter speed at the Variac was turned down to 20V from 40
This counter pumps air for 1 minute in every 20 minutes. Soft foam in bags used to minimize this shaking as it is clamped.
I think we can put ø2mm × 10mm long magnetic material inside 4 holes with actuation magnets. Then magnetic field on the other side of the mirror will be close to one produced by actuation magnet. Magnetic cylinder center of inertia will be in the vertical plane where mirror's center of inertia is. So this should not change alignment significantly. Eddy current dumping will be applied to the end of the magnetic cylinder opposite to the magnet using aluminium disks, we have them in the clean room.
I've tested this approach. As we do not have required cylinders with high magnetic permittivity, I replaced them with magnets simular to actuator magnets ø2mm × 3mm long. Using them and aluminium disks from other TT I've made a "pitch dumping" construction.
Pitch Q reduced but not that much as I could expect. I did a ringdown test.
yaw ringdown using original construction | yaw ringdown with added pitch damping
pitch ringdown using original construction | pitch ringdown with added pitch damping
From this data I've estimated Q factor for yaw (135 vs 88) and pitch (192 vs 77) (original vs added pitch damping). Thess results diverges with the ones obtained by designes. They measured Q~40-50 for original construction. Pitch and yaw have 2 close resonances so this time domain method can not be very precise. I've measured the same with SR785.
In these comparison plots excitation was not the same as coils are not plugged in yet, but resonance Q factors can be compared.
From this data I've estimated Q factor for yaw (135 vs 88) and pitch (192 vs 77) (original vs added pitch damping).
I've made a more precise measurement of pitch damping using spectrum analyzer.
Measurements confirm that damping using small actuation magnets reduces pitch Q by a factor of 4 and is not enough.
I've tested the idea to use coils as eddy current dampers. I terminated them with a wire and measured Q factor during the ringdown test. Sadly, I did not see any significant damping and Q was ~150. We need stronger magnets if we want eddy current dumping down to Q~1.
We need stronger magnets if we want eddy current dumping down to Q~1.
I've inserted 10mm * 10mm magnets to the 4 corner holes on the front side of the mirror frame according to actuation magnets polarity. I realigned TT and measured Q factor for pitch and yaw, it was 5-10.
I was able to do it for 1 TT only, because others have smaller (~0.1 mm) hole diameter and magnets can't go inside. I tried to warm holes up to 850 F but still was not able to insert a magnet.