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ID Date Author Type Categorydown Subject
  13570   Tue Jan 23 16:02:05 2018 SteveConfigurationSEIload cells

1500 and 2000 lbs load cells arrived from MIT to measure the vertical loads on each leg.

Quote:

We've been thinking about putting in a blade spring / wire based aluminum breadboard on top of the ETM & ITM stacks to get an extra factor of 10 in seismic attenuation.

Today Koji and I wondered about whether we could instead put something on the outside of the chambers. We have frozen the STACIS system because it produces a lot of excess noise below 1 Hz while isolating in the 5-50 Hz band.

But there is a small gap between the STACIS and the blue crossbeams that attache to the beams that go into the vacuum to support the stack. One possibility is to put in a small compliant piece in there to gives us some isolation in the 10-30 Hz band where we are using up a lot of the control range. The SLM series mounts from Barry Controls seems to do the trick. Depending on the load, we can get a 3-4 Hz resonant frequency.

Steve, can you please figure out how to measure what the vertical load is on each of the STACIS?

 

  13631   Tue Feb 13 21:22:44 2018 SteveUpdateSEIone load cells tested

Gautam and Steve,

The "called 225 lbs" steel crane load measured right on 102 kg

The trick to the measurment to maintain 1 mm gap to the central cilynder of the load cell.

The lead plate stabilized the large load.


gautam: some additional notes:

  1. the wiring on the Omega controller unit as given to us was wrong - I had to fix this on the D-sub connector in order to get the load cell to work. something to check for the other units.
  2. the main difficulty in doing this calibration run was that the readback is very sensitive to tilts of the load relative to the sensor.
  3. the problem is complicated by the fact that the load cell itself does not have a flat surface - it has a ring that protrudes above the flat face of the cylindrical load cell by a few mm as Steve mentioned.
  4. so in order to measure the weight of our stacks, we have to mitigate this problem and ensure that the full load of the stack is normally incident on the load cell - if the load cell itself is somehow torqued during the measurement because of the distribution of the load on it being uneven, we get an inaccurate measurement.
  5. In this calibration measurement, we think the error is <1% (true mass is 102kg, we measure 104kg on the meter which seems reasonable as the sum of the donut + lead plate)

  13806   Wed May 2 10:03:58 2018 SteveHowToSEIpreparation of load cell measurement at ETMX

Gautam and Steve,

We have calibrated the load  cells. The support beams height monitoring is almost ready.

The danger of this measurment that  the beams height changes can put shear and torsional forces on this formed (thin walled) bellow

They are designed for mainly axial motion.

The plan is to limit height change to 0.020" max

0, center oplev at X arm locked

1, check that  jack screws are carrying full loads and set height indicator dials to zero ( meaning: Stacis is bypassed )

2, raise beam height with aux leveling wedge  by 0.010"  on all 3 support point and than raise it an other 0.005"

3, replace levelling wedge with load cell that is centered and shimmed.     Dennis   Coyne pointed out that the Stacis foot has to be loaded at the center of the foot and formed bellow can shear at their limits.

4, lower the support beam by 0.005" ......now full load on the cells

Note: jack screw heights will not be adjusted or  touched.......so the present condition will be recovered

Quote:

We could use similar load cells   to make the actual weight measurement on the Stacis legs. This seems practical in our case.

I have had bad experience with pneumatic Barry isolators.

Our approximate max compression loads are 1500 lbs on 2 feet and 2500 lbs on the 3rd one.

 

 

  13809   Thu May 3 09:56:42 2018 SteveHowToSEIpreparation of load cell measurement at ETMX

[ Dennis Coyne'  precision answer ]

Differential Height between Isolators

According to a note on the bellows drawing (D990577-x0/A), the design life of the bellows at ± 20 minutes rotational stroke is 10,000 cycles. A 20 minute angular (torsional) rotation of the bellows corresponds to 0.186" differential height change across the 32" span between the chamber support beams (see isolator bracket, D000187-x0/B).

Another consideration regarding the bellows is the lateral shear stress introduced by the vertical translation. The notes on the bellows drawing do not give lateral shear limits. According to MDC's web page for formed bellows in this size range the lateral deflection limit is approximately 10% of the "live length" (aka "active length", or length of the convoluted section). According to the bellows drawing the active length is 3.5", so the maximum allowable lateral deflection should be ~0.35".

Of course when imposing a differential height change both torsional and lateral shear is introduced at the same time. Considering both limits together, the maximum differential height change should be < 0.12".

One final consideration is the initial stress to which the bellows are currently subjected due to a non-centered support beam from tolerances in the assembly and initial installation. Although we do not know this de-centering, we can guess that it may be of the order of ~ 0.04". So the final allowable differential height adjustment from the perspective of bellows stress is < 0.08".   Steve:  accumulated initial stress is unknown.  We used to adjust the original jack screws for IFO aligment in the early days of ~1999. This kind of adjustment was stopped when we realized how dangereous it can be. The fact is that there must be unknown amount of accumulated initial stress. This is my main worry but I'm confident that 0.020" change is safe.

So, with regard to bellows stress alone, your procedure to limit the differential height change to <0.020" is safe and prudent.

However, a more stringent consideration is the coplanarity requirement (TMC Stacis 2000 User's Manual, Doc. No. SERV 04-98-1, May 6, 1991, Rev. 1), section 2, "Installation",which stipulates < 0.010"/ft, or < 0.027" differential height across the 32" span between the chamber support beams. Again, your procedure to limit the differential height change to < 0.02" is safe.

Centered Load on the STACIS Isolators

According to the TMC Stacis 2000 User's Manual (Document No. SERV 04-98-1, May 6, 1991, Rev. 1), section 2, "Installation", typical installations (Figure 2-3) are with one payload interface plate which spans the entire set of 3 or 4 STACIS actuators. Our payload interface is unique.

Section 2.3.1, "Installation Steps": "5. Verify that the top of each isolator is fully under the payload/interface plate; this is essential to ensure proper support and leveling. The payload or interface plate should cover the entire top surface of the Isolator or the entire contact area of the optional jack."

section 2.3.2, "Payload/STACIS Interface": "... or if the supporting points do not completely cover the top surface of each Isolator, an interface plate will be needed."

The sketch in Figure 2-2 indicates an optional leveling jack which appears to have a larger contact surface area than the jacks currently installed in the 40m Lab. Of course this is just a non-dimensioned sketch. Are the jacks used by the 40m Lab provided by TMC, or did we (LIGO) choose them? I beleive Larry Jones purchased them.

A load centering requirement is not explicitly stated, but I think the stipulation to cover the entire top surface of each actuator is not so much to reduce the contact stress but to entire a centered load so that the PZT stack does not have a reaction moment.

From one of the photos in the 40m elog entry (specifically jack_screw.jpg), it appears that at least some isolators have the load off center. You should use this measurement of the load as an opportunity to re-center the loads on the Isolators.

In section 2.3.3, "Earthquake Restraints" restraints are suggested to prevent damage from earth tremors. Does the 40m Lab have EQ restraints? Yes, it has

Screw Jack Location

I could not tell where all of the screw jacks will be placed from the sketch included in the 40m elog entry which outlines the proposed procedure.

Load Cell Locations

The sketch indicates that the load cells will be placed on the center of the tops of the Isolators. This is good. However while discussing the procedure with Gautam he said that he was under the impression that the load cell woudl be placed next to the leveling jack, off-center. This condition may damage the PZT stack. I suggest that the leveling jack be removed and replaced (temporarily) with the load cell, plus any spacer required to make up the height difference. Yes

If you have any further question, just let me know.

    Dennis

 

 

Dennis Coyne
Chief Engineer, LIGO Laboratory
California Institute of Technology
MC 100-36, 1200 E. California Blvd.

 

 

 

  13840   Mon May 14 08:55:40 2018 Dennis CoyneHowToSEIpreparation of load cell measurement at ETMX

follow up email from Dennis 5-13-2018. The last line agrees with the numbers in elog13821.

Hi Steve & Gautam,

I've made some measurements of the spare (damaged) 40m bellows. Unfortunately neither of our coordinate measurement arms are currently set up (and I couldn't find an appropriate micrometer or caliper), so I could not (yet) directly measure the thickness. However from the other dimensional measurements, and a measurement of the axial stiffness (100 lb/in), and calculations (from the Standards of the Expansion Joint Manufacturers Association (EJMA), 6th ed., 1993) I infer a thickness of 0.010 inch in . This is close to a value of 0.012 in used by MDC Vacuum for bellows of about this size.

I calculate that the maximum allowable torsional rotation is 1.3 mrad. This corresponds to a differential height, across the 32 in span between support points, of 0.041 in.

In addition using the EJMA formulas I find that one can laterally displace the bellows by 0.50 inch (assuming a simultaneous axial displacement of 0.25 inch, but no torsion), but no more than ~200 times. I might be good to stay well below this limit, say no more than ~0.25 inch (6 mm).

If interested I've uploaded my calculations as a file associated with the bellows drawing at D990577-A/v1.

BTW in some notes that I was given (by either Larry Jones or Alan Weinstein) related to the 40m Stacis units, I see a sketch from Steve dated 3/2000 faxed to TMC which indicates 1200 lbs on each of two Stacis units and 2400 on the third Stacis.

  16783   Mon Apr 18 14:52:47 2022 Ian MacMillanSummarySEISeismic Study of Buildings and Caltech Campus

[Ian, JC]

I want to take measurements of seismic noise at different places on Caltech's campus and in different buildings. I will try to use the accelerometer in my phone for this but first I must calibrate it (Against the 40m accelerometers). 

I placed my iPhone 11 pro next to the seismometers at the 40m MC as seen in Attachment 1.

The calibration from the instrument was done using cts/rthz * 1V/16384cts * 1/ampgain * g/10V * 10m/s^2/g. The ampgain for all was 100.

Next, I took 100 seconds of data on both the iPhone and the three orthogonal Wilcoxon accelerometers.

The ASD for both of the total acceleration is shown in Attachment 2

The ASD for the individual directions acceleration is shown in Attachment 3

The coherence between the individual directions acceleration and the 40m's individual directions is shown in Attachment 4. For this calculation, the 40m data were downsampled to roughly match the phone's sample rate. This coherence is not very good. It should be higher. Because the phone and 40m sensors were picking up the same data as the phone. Because of this I also looked at the coherence between the individual 40m sensors.

In Attachment 5 I look at the coherence between the individual 40m sensors. This should give me a good idea of whether this is some other issue giving me mow coherence. This plot shows that the coherence between the individual 40m sensors is much better than between the phone and the 40m sensors.

Now I wanted to see what kind of data the iPhone could get from real-world tests. I placed it in a number of locations described below and plotted their ASDs in Attachment 6. The locations are thus:

Identifier  Location Notes
QIL QIL Lab in the Sub-basement of west bridge In sub-basement not much activity when taking measurements.
WBSH West bridge sub-basement hallway on floor in hallway no activity around
WB1H West Bridge 1st floor Hall placed on the floor near pillar near stairs to LIGO offices on the ground floor of west bridge
40m desk on my desk at the 40m placed on the desk while people were walking around and I had my feet on the desk. should be noisy

Notice how at the low end the amplitudes follow the relative amplitudes I would expect. QIL and WBSH are the lowest then WB1H is noisier and 40m desk is the noisiest. However, this is only true up until about 0.5 Hz then they all overlap. Since I would expect the 40m desk should be much noisier at all frequencies I suspect that the phone accelerometer is not suitable for measurements higher than 0.5 Hz.

Possible Problems:

One possible problem with my measurement is that my phone was in a leather case. this may have damped out higher frequencies. Also, my phone was not weighed down or bolted to the floor. this stronger connection would make it better at detecting higher frequencies. I could repeat the experiment with no case and a weight on top of my phone.

What's next:

Since I don't think the phone can give me accurate data above 0.5Hz for quiet environments. It may not be suitable for this task. It would seem that the right instrument is the Wilcoxon 731A but it requires an amplifier that I can't track down.

 

I included all the data and code in the zip file in attachment 7

 

  16798   Thu Apr 21 17:32:35 2022 Ian MacMillanSummarySEISeismic Study of Buildings and Caltech Campus

[Rana, Ian]

We built a power supply for the accelerometer shown in Attachment 1 based on the diagram shown in the Wilcoxon manual and shown in attachment 2. We used a 9V power supply and a capacitor value of 680uF. We did not use a constant current diode. 

When hooked up to an oscilloscope we saw vibrations from hitting our hands on the table but we did not see the same amplitude in the negative and positive directions. For example, when I held the accelerometer and moved it down you would see a dip then a peak as the accelerometer accelerated down then accelerated up when I stopped the down word movement. But weirdly when I did the opposite (moved the accelerometer up the same dip then a peak appeared. This is a little concerning because it should be the opposite. it should be a peak then a dip. This in addition to the seemingly decreased sensitivity in one direction make me think that the accelerometer is broken.

I labeled the box with "might be broken" before I returned it to the cryo lab.

  17211   Tue Oct 25 14:29:56 2022 PacoSummarySEIEarthquake tripped SUS

[Yuta, Paco, JC]

This eq  potentially tripped ETMY, PR2, PR3, AS1, AS4, SR2, LO1, LO2 suspensions during today's WB meeting. We restored them into normal local damping.


We aligned the arm cavities just to verify things were ok and then moved on to BHD comissioning. No problems spotted so far.

  57   Fri Nov 2 08:59:30 2007 steveBureaucracySAFETYthe laser is ON
The psl laser is back on !
  115   Mon Nov 19 14:32:10 2007 steveBureaucracySAFETYgrad student safety training
John Miller and Alberto Stochino has received the 40m safety bible.
They still have to read the laser operation manual and sign off on it.
  196   Tue Dec 18 16:50:35 2007 tobinUpdateSAFETYuvex laser safety glasses defective
A few days ago we noticed what appeared to be a blotched, speckled fracturing of the coating of the "UVEX" laser safety glasses. These are the glasses with "transparent" (reflective to 1064nm) lenses and white frames that we keep in a box on top of a filing cabinet in the control room. Today Steve measured the transmission of these glasses and found 80% transmission of 1064nm in several cases.

Do not use the white, transparent "uvex" laser safety glasses until further notice. Steve has hidden them away so that you won't be tempted.

Below is attached a photo of a bad lens.
  203   Wed Dec 19 16:40:12 2007 steveUpdateSAFETYlaser safety glasses measured
I measured the coarse transission at 1064nm of the 40m safety glasses today.

12 pieces of UVEX # LOTG-YAG/CO2 light green, all plastic construction, ADSORBANT

3 pieces of 6KG5, Scott colored filter glass type,

individual prescription glasses: alan, bob, ben, jay and steve

7 pieces of dual waveleght glasses

These glasses showed 0.00mW transmission out of 170mW Crysta Laser 1064
  443   Thu Apr 24 15:57:53 2008 steveConfigurationSAFETYSafety at AP-ISCT
I measured the output power of the psl after the mechanical shutter.

It was 1.1 W with Ophir power meter, than unlocked the MC and measured
the power at the MC-REFL Beam Dump at the AP-ISCT 0.9 W
Power on MC-REFL photodiode 92 mW

High power metal beam shields were installed around the beam path of
MC-REFL between AP-Viewport and MC-REFL Beam Dump.
Placed HIGH POWER LASER BEAM PATH warning signs on table frame and top
covers.

Last week I placed a small monitor on the top of the OOC that
monitors the resonant spot of MC2. Please keep an eye on this monitor
when working on the AP-ISCT

AP table should NOT be left uncovered. One experienced laser operator
has to be present if the top is removed and IR-viewer scan required.
We need your full cooperation to keep this lab safe.
  488   Tue May 20 09:28:42 2008 steveBureaucracySAFETYsafety traning for 40m
Tara Chalernsongsak, new gradstudent for K. Libbrecht was introduced to the basics of the 40m operations.
  491   Thu May 22 11:21:45 2008 steveBureaucracySAFETYearly surf sudent
Caltech under grad Eric Mintun received the 40m safety training.
Now he has to read and sign SOP of laser and ifo.
He'll be working with GigE cameras with Joe
  523   Fri Jun 6 15:56:00 2008 steveBureaucracySAFETYYoichi received safety training
Yoichi Aso received 40m specific safety training.
  539   Wed Jun 18 16:37:54 2008 steve,ranaUpdateSAFETYCO2 test in the east arm
The CO2 laser and table are in the east arm for characterization of the mechanics. We
will not be operating it until we have an SOP (which is being written). No worries.
  552   Mon Jun 23 15:22:04 2008 ranaBureaucracySAFETYLaser Safety Walkthrough today
  708   Mon Jul 21 15:52:22 2008 steveBureaucracySAFETYfire alarms test
The fire alarm test and evacuation drill was successfully completed at 13:45 Wednesday, July 16, 2008

Everybody was on time for the 40m meeting.
  840   Fri Aug 15 14:12:31 2008 steveBureaucracySAFETYsafety glasses required
The MOPA shutter is opened,
the PSL enclosure is switched to bypass mode,
manual block removed from PMC,

the PSL output is still blocked and the mechanical shutter is still closed.

Pumpdown is at 300 Torr continuing

Laser safety glasses are required!
  865   Thu Aug 21 10:24:20 2008 steveConfigurationSAFETYlaser safe mode condition
The MOPA and PSL shutters are closed.
Manual beam blocks are in place.
Enclosure interlock is enabled.
No other high power laser is in operation.

We are in laser safe of operation for visiting students from Japan

NO safety glasses required
  866   Thu Aug 21 16:28:59 2008 steveConfigurationSAFETYsafety glasses required
I just opened the MOPA shutter so PA is warming up.

High power beam path is cleared and laser safety glasses required.
  942   Thu Sep 11 14:27:53 2008 steveBureaucracySAFETYsafety training
Peter Kalmus received 40m specific safety training last week.
  1004   Mon Sep 29 11:17:14 2008 steveUpdateSAFETYhorizontal viewports are protected with lexan
The four horizontal viewports of arms are protected
by 3/8" thick, 8.5" OD Lexan disk of MR10 Polycarbonate.

ITMX, ETMX, ITMY and ETMY ccd cameras are not focused now.
  1068   Wed Oct 22 16:22:53 2008 steveBureaucracySAFETYCaryn received safety training
Caryn Polatchi has received 40m safety training on Monday, Oct 20
  1082   Fri Oct 24 11:09:08 2008 steveUpdateSAFETYmore lexan plates under cameras
The MC2, MC3&1 and BSC-SUS cameras were repositioned somewhat in the
process of placing lexan disks under neat them.
MC1&3 will have to be readjusted.

Now all horizontal viewports are protected.
  1123   Fri Nov 7 16:05:55 2008 steveBureaucracySAFETYinsect killer sprayed at kitchen area !

Bob and I cleaned out the sink area and sprayed
Spectracide's BUG STOP insect killer solution on the shelfs and sink
table top area.

NO eating or coffee drinking till Monday

This is an effort to stop the ants coming.
  1243   Thu Jan 22 08:34:10 2009 steveBureaucracySAFETYsafety training
Kakeru received 40m safety training yesterday.

He has no authorization to work alone in the high power beam path yet.
  1273   Thu Feb 5 09:12:29 2009 steveBureaucracySAFETYsafety updates & fire alarm test

The fire alarm test was completed at 13:30 yesterday.

 

I updated the 40M Emergency Calling List by replacing Rob by Yoichy. The calling order: Vass,  Aso and Taylor.

Rana and Yoichy were added to the "Registered PSL Operator List"  and posted it in the lab. (not in the document, that should be up dated)

We are getting ready for the annual safety audit. It will be held next week  at 14:00 Friday, Feb 13, 2009

Please participate in the preparation by correcting it or just  tell me.

 

Rod Luna is organizing the pick up of the following old equipment:

HP laser jet  5000n, 3 of 19" 10 base-T network ports and  4 small hubs,

2 Sun monitors, 1 Viewsonic monitor, 7 keypads and

Hitachi scopes 2 of V-355, 2 of V-422, 1 of V-202 and 1 of V-6165

 

 

  1280   Fri Feb 6 14:49:31 2009 steveSummarySAFETYlaser inventory
40M Laser Inventory at Feb 05, 2009
 

1, Lightwave PA#102 @ 77,910 hrs 1064nm of 2.8W @ 27.65A
                   NPRO#206 @ 2.4A                    at PSL enclosure............"Big Boy" is waiting for to be retired but not now.

2, Lightwave  NPRO 1064nm of 700mW  #415   at AP table.......cavity length measurements of Alberto

3, CrystaLaser  IRCL-100-1064S, 1064nmS of 100mW  ,sn#IR81132 at east arm cabinet

4, CrystaLaser 1064nm of 180mW # -1274 flq at scattering setup.........flashlight quality

5, RF-PD tester 1064nm of 1.2mW @20mA at SP table

6, Lumix 800-1100nm of 500mW at east arm cabinet

7, JDS-Uniphase 633nmP of 4mW oplev sus laser at 5 places,
    plus four spares in east arm cabinet
 
 
The same information is posted at the 40M WIKI also
 
 
 
  1288   Tue Feb 10 10:48:48 2009 steveBureaucracySAFETYsafety glasses scanned
All 40m safety glasses are absorbent.
 
They were scanned by 180 mW  2mm spot size  of 1064 nm beam and  their  transmissions were measured
They showed no degradation.
 
UVEX 's  LOTG-YAG/CO2 glasses (fits over personal glasses) 11 pieces,
Glendale-XC by Bacou-Dalloz,  #1166218VLT68% , aerodynamic style, 7 pieces, (4 missing )
KG5- glasses , heavier- made out of glass, 3 pieces,
Thorlab's LG10, 1 piece
Old glasses by "Laser Glass" Nd-YAG, 2 pieces
Totaling 24
 
Atm.2  showing our muilty wavelength glasses of 1064 and 530 nm
Their transmittance for both wavelength were zero.
 
Note: if you have prescripton safety glasses I would like to scan it for you !
 
 
 

 

 

  1319   Wed Feb 18 15:31:38 2009 steveBureaucracySAFETYemergency back-up lights checked
All 13 exit and  emergency back-up lights and their batteries were checked.
Two of  the batteries were replaced.
  1332   Mon Feb 23 11:07:01 2009 steveBureaucracySAFETYKiwamu receives safety training

Osamu and Kiwamu received 40m safety training on Thursday, Feb 19, 2009

Kiwamu needs Osamu's close supervision at PSL enclosure and AP table
I hope they already read, understood and signed the laser SOP
  1700   Wed Jun 24 17:08:16 2009 steveBureaucracySAFETYsurf student safety

The 40m lab specific safety training is done. The participants were

Stephanie Erickson, Clara Bennett, Chris Zimmerman, Zach Commings, Michelle Stephen surfs and Drew Cappel  postock.

They have already went through the Caltech Safety Office laser and general safety training.

They still have to read, understand and sign the the SOP for the laser & lab

  1802   Wed Jul 29 11:15:06 2009 steveBureaucracySAFETYKevin receives safety training

Kevin Vigue, our high school summer student went through the 40m specific safety traning yesterday.

  2015   Mon Sep 28 23:44:18 2009 KojiOmnistructureSAFETYCrappy power outlet

Jenne, Koji

Tonight we found that the wireless for Martian network was down.
We inspected the router and found the power was down. The power of the weather station was also down.

By touching the power outlet which they are connected, the power changes on and off.
This problematic power outlet has a label "L#17" just below the photograph of the mk I (1989).
The plug was connected to the left one.

As it was scary, we moved the power plug to the next one (L#19).
The wireless router and the weather station were powered now,
though the weather station is showing a wrong time in its clock.

  2082   Mon Oct 12 17:27:20 2009 KojiConfigurationSAFETYStray beam blocking

Steve, Kiwamu, and Koji

We went through the PSL table to make sure any strong beam did not hit the wall.

We found that the reflection of Stephanie's OSA returned its path down to the beamsplitter.
This BS reflect that beam to the wall. That was fixed.

The surprising was that the relatively strong beam (~1mW?) went through the steering mirror
just before the PMC. We put thorlabs razor blades. I am still thinking what this indicates...
because the beam had been blocked if it was such from long time before.

During the work we found some stray optics such as a cube BS, a flipper mirror, and so on.
We can see them in the photo as those enclosed with yellow circles.
One of the beams was obtained from the reflection of the ND filter (...almost illeagal), and 
was even hittting a metal fixture for the BS cube.

If someone uses these components for useful purposes,
please let me(Koji) know. Otherwise, they are removed next week.

The other thing we found was the bright scatter from the EOM for the PMC.
As this scatter is so blight, I am going to align it.

  2084   Mon Oct 12 18:38:07 2009 JenneConfigurationSAFETYStray beam blocking

Quote:

Steve, Kiwamu, and Koji

We went through the PSL table to make sure any strong beam did not hit the wall.

We found that the reflection of Stephanie's OSA returned its path down to the beamsplitter.
This BS reflect that beam to the wall. That was fixed.

The surprising was that the relatively strong beam (~1mW?) went through the steering mirror
just before the PMC. We put thorlabs razor blades. I am still thinking what this indicates...
because the beam had been blocked if it was such from long time before.

During the work we found some stray optics such as a cube BS, a flipper mirror, and so on.
We can see them in the photo as those enclosed with yellow circles.
One of the beams was obtained from the reflection of the ND filter (...almost illeagal), and 
was even hittting a metal fixture for the BS cube.

If someone uses these components for useful purposes,
please let me(Koji) know. Otherwise, they are removed next week.

The other thing we found was the bright scatter from the EOM for the PMC.
As this scatter is so blight, I am going to align it.

 These components are from when Rana and I used the StochMon PD to do the RFAM tuning, documented in elog 1926.  This was a very handy measurement, but I'm not sure if whether or not we need it often enough to keep the optics there.

  2085   Mon Oct 12 19:53:44 2009 KojiConfigurationSAFETYStray beam blocking
I aligned the EOM and the beam to the PMC.
The beam is still hitting the bottom of the EOM aperture,
but the further lowering the EOM reduces the PMC transmission.
So I put my compromise.

The work restored the PMC transmission to over 2.4.

Finally I centered the beams on to the MC WFSs.
As a result, the MC Trans recovered 7.5.
  2087   Mon Oct 12 20:01:13 2009 KojiConfigurationSAFETYStray beam blocking

OK! I saw the optics are redundant and some of the components are not in a right place.
I will talk with you when you are back such that we can keep the usefulness of the setup.

Quote:

 These components are from when Rana and I used the StochMon PD to do the RFAM tuning, documented in elog 1926.  This was a very handy measurement, but I'm not sure if whether or not we need it often enough to keep the optics there.

 

  2115   Mon Oct 19 11:00:52 2009 steveHowToSAFETY40m safety training

Kiwamu, Alex and Zach are practicing mandatory IR-safety scan at the 40m-PSL

40m specific safety indoctrination were completed.

  2130   Wed Oct 21 16:18:12 2009 SteveSummarySAFETYLIGO Safety Officers visited the 40m

David Nolting, chief LIGO Safety Officer and his lieutenants from LLO and LHO paid homage to the 40m lab this morning.

They give us a few recommendation: update safety documents, move optical table from the front of ETMX-rack and label-identify absorbent plastics on enclosure windows-doors.

We'll correct these short comings ASAP

 

  2482   Wed Jan 6 16:48:52 2010 steveBureaucracySAFETYcopied NPRO key

We lost our key to the Lightwave 125/6-OPN-PS   The key shop just made one look a like that works.

  2647   Mon Mar 1 08:49:37 2010 steveBureaucracySAFETYsafety audit

The 40m safety audit will be at Wednesday afternoon, March 3

Please participate getting our lab to inspection grade safety level.

  2716   Fri Mar 26 10:48:35 2010 steveUpdateSAFETYsafety glasses measured

Safety glasses 1064 nm transmission measured at ~200 mW level. They are all good.

  2814   Tue Apr 20 09:15:15 2010 steveSummarySAFETYannual safety audit
  2815   Tue Apr 20 10:55:10 2010 steveBureaucracySAFETYKevin Kuns received safety training

The 40m's new undergrad Kevin Kuns was introduced to 40m safety hazards. He is new and needs guidance as specially with 2W laser work.

Peter King will train him on Friday to LIGO-laser standard.

 

  2943   Tue May 18 11:54:29 2010 steveConfigurationSAFETYpsl mechanical shutter is not working

As we learned yesterday, the PSL laser power out put mechanical shutter is not working in the remote mode. It only works in local manual mode.

Do not rely on the MEDM screen monitor readout! The position is only changing on the monitor. The main beam must be blocked before the output periscope.

  2947   Tue May 18 15:09:02 2010 steveConfigurationSAFETYPSL output shutter in order again

Quote:

As we learned yesterday, the PSL laser power out put mechanical shutter is not working in the remote mode. It only works in local manual mode.

Do not rely on the MEDM screen monitor readout! The position is only changing on the monitor. The main beam must be blocked before the output periscope.

Ben found the Sorenson 5V ps off. It was turned off since our last scheduled power outage. I wonder what else is running on 5V in the PSL? This power supply should be on the

"alarm handler"  list to avoid future repeat of this condition. However a real safety switch would have confirming position sensors of the shutter open or closed. Is there such thing at the sites?

  2961   Thu May 20 20:03:37 2010 JenneUpdateSAFETYDon't walk down the Y(new convention) arm tonight!

Please don't go down the Yarm (Old Xarm) for right now, or if you do, please be very careful.  Kiwamu and I are set up to take beam scan measurements down the walkway, and so there are some cables / carts / other stuff down there.  We are going to get dinner really quickly before beginning the measurements. 

Right now, the PSL shutter is Closed, so there is no beam hazard outside of the chambers, just crowded space hazard.

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