Enclosure is at the east end. It has it's bottom o-ring in place. It will be ready for optics tomorrow around 5pm
I have to shim out the enclosure, finish leveling the table and cut surgical tubing O-ring for the top.
Glued surgical latex tubing with super glue into O-ring shape. The existing in place tubing K-100, OD 0.125" (actual size 0.140"), wall 0.031", ID 0.062".
I have just found out that tolerances on tubing OD are + - 0.026" by the manufacturer. I'm getting larger tubing for better fit.
The table is ready for optics.
Things left to do:
1, finalize o-ring size 2, finish cable feedthrough 3, finalize window connection 4, IR-Thermashield strips for bridge sides 5, replace bridge support post with solid one
I'm working on to improve the quality of the enclosure.
The short comings are: more cable feedthroughs needed, latches to anchor top covers air tight and posts to support bending bridges.
Red triangles are compression latches at 10 places to hold the top air tight on surgical tubing
Green lines represent 4 posts of Al 1" OD to support the covers and maximize their eigenfrequencies.
Black crosses are 4 spring loaded push-bottom quick release pins to anchor the top covers to the bridges. This connection will not be air tight.
(quarter-turn wing head fastener have the same problem) I'm thinking of some solution to minimize the leak.
Violet _ steel plate (1" wide, 15" long, 0.125" thick) between the two posts will anchor the quick release pins and make bridge rigid.
Blue rectangle is an other cable feedthrough exiting on the chamber side.
Planning to substitute window with soft - air tight ( Aluminized thin wall hose ) connection to vacuum view port where white circle is representing the Al adaptor ring.
Updated after Wednesday meeting 4-24-2013
We'll follow LIGO policy:
Our policy is to use first contact within 1 year of purchase for use in the interferometers. For inspection use I am comfortable with out-of-date use.
GaryLinn offered their indate First Contact for use.
Alex and Steve,
Old halogen chamber illuminator cabling disconnected and potenciometer board removed at 1Y1 in order to give room for pd calibration fibre set up.
During the process, they had also removed the power cable to the ITMY camera. Steve and I fixed this...so the camera is back.
IN VACUUM beam heights are ALL 5.5" This is measured from the top of the optical table to the center of all TMs, mirrors and other optical components. This beam is ~36" above the floor.
PSL (inside of enclosure) main-output beam: PMC, MZ, RC and ISS are at 3" heights. IOO Angle & Position, MC-Trans and RFAM qpds are at 4"
ALL OTHER beam heights at atmosphere and different ISCT (interferrometer sensing, control optical table)s are at 4"
The Napa earth quake magnitude 6 did not have any effect on the suspensions.
The Goy phase upgrade was done nicely. The IOO pointing did not change. Credit owned to Nick and Andres.
IFO is locked right on.
This is the third morning in a row that the MC2 was tripped. Would you look at it Koji?
This may be cause by the impact of crazy WFS signal after the lock loss.
The auto locker is not fast enough to shut the WFS down before the mirrors are kicked.
Jenne and I discussed the issue and agreed that this can be solved by implementing
the same triggering algorithm as the LSC triggers.
Give us a bit more time to work on this.
This is the third morning in a row that the MC2 was tripped.
MC2 was tripped again. I think the answer is that watchdog's critical value was too small C1:SUS-MC2_PD_MAX_VAR = 10, so seismic could trip MC2. I've changed the value to 100.
Just a reminder that a film crew will be here Monday morning, filming Christian Ott for some Discovery channel show.
They are slated to be here from 8am to 12:30pm or so. They will take a couple of shots inside the lab, and the rest of the filming should be of Christian in the control room (which they will "clean up" and fit with "sexy lighting"). I will try to be here the whole time to oversee everything.
Konecrane Fred was early this morning. He diagnosed the ETMY crane horizontal drive gear box dead and left just before the film crew showed up.
New gear box should be here by the end of this week for installation.
The lab air quality is high ~20,000 counts of particles of 0.5 micron. Keep an eye on this before you open the chamber.
Pitch damping solution needed! It should be in the machine shop already.
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.
Too bad - I thought it would at least give a little damping. Since we want the viscous-like energy loss to be ~49x larger, we need to have the field modulation in the damper (not dumper) increase by ~7.
I've made SolidWorks models of damping bracket and eddy current disk. They will me manufactured and used instead of old ones. New bracket will be mounted in exactly the same place where the old one was. Drawings might not be complete but all dimensions are in the models so we can fix drawing tomorrow before going to machine shop.
I think we can use ring magnets for passive damping. Then we won't have the vent problem. I've found some at K&J Magnetics, we can get them any time. Magnets are Ni-Cu-Ni (fine for vacuum?) Diameter is 3/8'' with advertised tolerence 0.004'', so they should fit the holes.
Koji and Steve pointed out that previous design of a damping bracket was a bit complicated to manufacture. So I made it simpler and also added a tap hole for original yaw damping. We'll give drawing to Mike in the machine shop tomorrow morning.
I've purchased K&J magnets for eddy current damping, they should be here in 2 days.
Den mentioned that the disks will have threaded holes, and that he has made a note to that effect on the paper copy of the drawing that he will bring to Mike at the shop. Also, all threaded holes in the new plate are marked on the paper copy.
Wow... This is even more complicated than the original "Y" design...
We've received all parts that we need for eddy current damping. I've made an estimate of Q with dirty tip-tilt. It looks fine (Q~1)
We need to check ring magnets for vacuum compatibility. Bob start baking on Friday.
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.
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?
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.
[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
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.
Batteries replaced in control room UPS after 3 years from replaceUPSbattery.com
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.
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.
This AmScope microscope would have 3.5x-180x magnification, calibratable measurement function, 5MP picture and good working distance to work on printed circuit boards.
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
The microscope shipped back to the vendor for credit yesterday.
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
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.
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.
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.
All 3 cranes inspected by professional Fred Goodbar of Konecranes and load tested with 450 lbs at max reach on Friday, March 3, 2017
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 and load tested with 450 lbs at max reach.
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.
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
No obvious sign of damage.
~Vancuver, Canada earthquakes: magnitude 6, 5 and more shaking