Previously, we had finished gathering the data for our study. Today, we took photos of all our microscope samples using a Nikon camera.

The results continued to show that fastening a SSTL nut onto a SSTL screw generated more metal dust when compared to testing the N60 nuts/screws. Additionally, the results also continued to show that more rotations of a nut onto a screw correlates to a greater amount of dust generated. For the future, we will analyze our findings in more depth and also create a slideshow to present these findings. We may also want to find a program that we can use to count the particles in the sample photos.

See images attached for the images of our samples taken from our camera.

Log for Thursday, May 18, 2023:

Previously, when we worked in the clean room, we made progress in determining results from using different microscope plates. Since we had observed proficient preliminary results on the microscope samples, we were able to finally start gathering data.

The materials of the nuts and screws used for our samples were divided into three categories: SSTL screw and nut, N60 screw and nut, and N60 screw and SSTL nut. For each category, there were also three sub-categories of how many times the nut was fastened onto the screw: 15 times, 30 times, and 60 times.

Results showed that fastening the SSTL nut onto the SSTL screw generated more metal dust when compared to any experiments using N60 nuts/screws. For the future, we will analyze the differences between all the categories and subcategories of the samples collected and also take pictures of our samples with a professional camera.

See images for the results of this data collection taken by our microscope software.

Log for Wednesday, May 17, 2023:

Previously, when we worked in the clean room, we still found some problems with observing our results, most likely due to the microscope slides we were using. Therefore, today, we started using new, more-advanced, microscope slides that were spotless coming out of the box. We found that the results of our experiments were much clearer and we could actually see the metal particles generated.

On one slide, we fastened the SSTL nut 10 times around the SSTL screw and on another slide, we fastened it 30 times. There wasn’t a major difference between the results of the two slides, so for the future, we will repeat this with the same SSTL nut and SSTL screw in hopes of finding a greater difference in our observations. We will also test the N60 nuts and screws in a similar manner in order to compare it to the SSTL nut and screw.

Log for Monday, May 15, 2023:

In previous experiments, there were some issues in determining what was actually generated dust from our experiments and what were from our laboratory surroundings. As a result, we decided to work in a clean room. After going through the full gowning sequence, we wiped down all of the surfaces and materials that we were working on before using them in the clean room for our experiments. See the image attached for our experiment setup in the clean room.

We weren’t able to finish our experiments, but we had gotten some preliminary observations from working in the clean room. We still found particles in our sample without conducting the experiment, so, for the future, we might need to find a different way to clean our microscope sample plates.

Log  for Friday, May 13, 2023:

In previous experiments, there were some issues in determining dust particles from other, unnecessary particles, as well as the background. To resolve this, we elevated our microscope sample using two metal blocks. This, effectively, cleaned up the microscope visuals by decreasing the amount of background distractions.

Additionally, we limited our data collection spot to a smaller, rectangular area near the middle in order for our particles to scatter less when being generated. Specifically, we did this by covering the sides of our sample with smaller portions of microscope slides. See attached for both images near the end and near the middle of the sample, which shows the particles collected after fastening a clean SSTL nut onto a clean SSTL screw.

For the future, we will conduct experiments in a clean room in order to eliminate unnecessary particles from the laboratory surroundings. We will also find a more effective way to clean our microscope samples to completely eliminate unnecessary particles.

Log for Thursday, May 11, 2023:

Some experimenta were conducted with the microscope controls. One of the goals was to find how to increase/decrease the brightness of the light shown by the microscope in order to better observe the particles in the sample. Another goal was to find some sort of “counting” tool to use  in order to count the particles gathered in the sample. We were able to find the control to increase/decrease the brightness of the image, but not of the light displayed by the microscope itself, and we still weren’t able to find the “counting” tool.

Afterward, we cleaned some of the nuts and screws with isopropanol to observe if the dust gathered in the sample is actually from fastening the nut on the screw or from the already-dirty screw/nut. See photo attached.

For the future, we will continue to experiment with the microscope controls in order to view the dust particles in the sample more accurately, which includes this brightness and "counting" feature. We may also need to find if we are using the correct microscope. We also still need to find better double-sided tape to use in order to better gather the dust particles, as well as create some sort of stand for the screw to sit in (so the dust will fall below in a more organized manner). Lastly, we will continue to experiment with cleaning various parts, perhaps in a clean room.

Just now, I moved the ROMER Arm CMM back to the Machine and Metrology Room (Downs 228). Photos will be posted here.

• CMM property tag C22191
• Laptop property tag C22190

I need to touch base with the Filippone group to let them know that this move took place, and to relocate the calibration reference bar.

Introduction: These sets of experiments will be used to determine the amount of dust gathered from the earthquake stoppers of certain materials. Specifically, the goal is to compare the dust gathered from a Ag-SSTL nut versus a N60 nut when fastened onto various screws (which include mainly those of SSTL but also of N60 and Ag-SSTL). Helicoils may also be used in the experimentation process. The purpose in doing this is to observe which combination of nut and screw will create the most minimal amount of dust after fastening the nut, as earthquake stoppers are used in vacuum systems, where the most minimal amount of dust is optimal.

The first set of experimentation mainly consisted of assembling the experiment and gathering some preliminary results.

First, double-sided tape was applied onto a microscope slide and, while over the double-sided tape, the Ag-SSTL nut was fastened onto a Ag-SSTL screw to create dust (in efforts that the tape will catch any dust generated). Results showed that the double-sided tape actually had numerous curved lines, most of which were not created by the experiment, thereby obstructing any view of dust. A subsequent test was then carried out without using tape, and as a result, more dust was able to be observed under the microscope.

To elaborate on the process, the Ag-SSTL nut was rotated five times near the very end of the Ag-SSTL screw to generate more dust. An equivalent test was then completed with the SSTL screw and nut. For both tests, photos of the microscope sample using green light were also taken to better define the particles observed. However, what was originally thought to be dust on the microscope slide may have actually been lint from the wipe used to clean the sample plate. See attachments below for preliminary photos of the particles gathered with and without the green light.

For future experimentation, more settings for the microscope will need to be found, including how to increase/decrease the brightness and the "counting" feature to count the particles shown in the sample. A different type of double-sided tape will also be used to better grab the particles gathered. The N60 screws and nuts have yet to be tested, so they will be included for subsequent experiments.

[Aidan, Camille]

We have set up the green and IR paths on the HPAD2 system.

Coordinate system: X = East-West, Y = North-South, Z = Up-Down

Green:

• Beam is collimated with a 100mm focal length lens placed that distance from the fiber launcher.
• Beam is steered up through the base of the test mass. We had to move the two 45 degree mirrors about 1.5" South (in the Y direction) in order for the green beam to be parallel to and 3" off the surface of the upper breadboard
• The two folding mirrors are separated by just over 3" in the X direction.
• We can see some green transmission through the top of the test mass when it is place.
• The reflection is steered onto the HWS via a 1:1 telescope of 2x 752mm focal length lenses. The first lens is placed an optical distance of 750mm from the HR surface of the optic, the two lenses are placed 1504mm apart and the HWS is placed 752mm from the second lens.
• We should probably clean the HWS optics as we can see a little bit of diffraction from dust.
• The 45 degree folding mirrors would be more robust if they were 2" diameter and had more solid mounts (this is an item to fix)

IR 

• The IR beam has been aligned through the Faraday using the red alignment laser
• Rejected beams from the Faraday still need to be dumped
• The transmission is steered onto the surface of the test mass. 
• The reflection is collected by a second mirror and will be steered into a beam dump

We have not yet turned on the IR laser - still need to check polarization of this and get it rotated correctly to transmit through the Faraday. Still need to add beam dumps on rejected ports and the main beam dump.

Actions taken this week:

• Placed PO for

Next steps (for next week):

• Cable routing
• Move breadboard to back side of A frame

[Stephen, Jordan, Camille]

We continued building the Zaber XY stage, following instructions in vendor manual link with notes at E2200112 google doc.

Some notes and lessons learned:

• The stepper motors and controller are all functional, yay!
  •  A homing test using the vendor's software was conducted, videos will be posted here.
  • First homing test used travel range 1250 mm, following instructions from vendor using stepper motor p/n; however, we found that this caused a crash at the far end of travel; actual max travel from home, considering physical constraints, is approximately 1200 mm, but we ordered a stage with 1000 mm travel. So, there's extra range, but 1100 mm is a good limit.
  • Manual stop button on controller seems to only pause sometimes; useful but better to use software stop.
  • One axis had home sensor installed in reverse orientation, so the homing failed during its homing test, causing a crash at the far end of travel.
• The cable for the Y axis was supplied incorrectly, and inconsistently with the packing slip (should have been a 16 pin to 25 pin cable, p/n MC10T3L300, but we instead received a 16 pin to 16 pin cable, p/n MC03L300.
  • Until a replacement is supplied, we can wire only 2 axes at any one time.
• The X and Y axes have been structurally joined, then mounted on 6" pylons.
  • Because of some interference between the bracing and the alignment bars, these were removed and can be reapplied when the vendor gives further instruction.
  • Calipers were used to square the axes and ensure parallelism, and the free X axis was driven through the squared axes to confirm the friction feels similar through the entire travel range.
• The correct Y axis cable has been received, installed, and routed.
  • This included an international FedEx Priority overnight shipment, a quick double check that the connectors would fit, and a 24 hour vertical hang.
  • The cable guide has been finalized; this long cable runs along the long axis as the stage is driven through its range of motion, and the cable guide articulates to retain a safe bend radius.
• All three of us have learned to use the control software, Zaber Launcher.
  • Software commands may be implemented through the GUI in some cases, for convenience, but all can be routed through an ASCII protocol Terminal.
  • Documentation relating to software (manuals, tips, discoveries, lessons learned) are compiled at E2200112.
• The breadboard and A frame are assembled and mounted.
  • We still require an interface plate to come through, hopefully in April.
  • We will next consider shielding to prevent turbulence in the Hartmann WFS path.
• Laser install and optical alignment may proceed next week (April 25th).

We have a stage which is needing a bit of fine tuning, an interface plate, and some software integration work, but overall the build has proceeded nicely.

[Stephen, Jordan, Camille]

We started building the Zaber XY stage, following instructions in vendor manual link with notes at E2200112 google doc.

Some notes and lessons learned:

• The motor - controller cables need to be straightened by 24 hours of vertical hanging "to relieve packaging stresses".
• In vendor terminology, the X axis is the longer lower rail, and the Y axis is the shorter upper rail.
• The vendor recommends testing device functionality before completeing structural assembly.
• We have all motors attached and are just about to attach the Y axis rails onto the X axis alignment bars.

With the cables needing to hang and the device functionality testing depending on those cables, we have paused until Friday. Complete stage structural assembly anticipated tomorrow!

[WIP Placeholder]

SN0818 and SN0654 (25 mm HR witness samples - SN0818 is ETM, SN0654 is ITM) were annealed between 08 and 15 February 2022 - used the large furnace in Downs 221, atmosphere was air, used glass petri dishes to protect optic (from Gabriele and CRiMe). Start time was 18:42 Pacific, and sample was removed at 11:00 on Monday morning after a 16 hour cooldown.

Controller parameters:

Ramp up rate = 100 °C per hour
Hold temp = 478 °C (To avoid any unintended over-temperature due to overshoot or steady state offset - the datalogger RTD and the controller RTD have some discrepency at high temperatures)
Hold time = 100 hours
Ramp down rate = 100 °C per hour

Annealing run on ETM HR coatings for long duration at high temperature, hoping to yield improvements to absorption.

Witness RTD observed a 497.1 °C overshoot and 14.5 °C offset from controller RTD. These parameters were consistent with the elog entries all entries, particularly the shorter duration ENG_Labs/263. See attached image of the temperature profile (.xlsx file is source document).

Optic is now with Liyuan in RTS for recharacterization after anneal.

SN1009 (80 mm witness sample) was annealed between 01 and 04 February 2022 - used the large furnace in Downs 221, atmosphere was air, used glass petri dishes to protect optic (from Gabriele and CRiMe). Start time was 09:56 Pacific, and sample was removed at 10:00 on Friday morning after a 16 hour cooldown.

Controller parameters:

Ramp up rate = 100 °C per hour
Hold temp = 478 °C (To avoid any unintended over-temperature due to overshoot or steady state offset - the datalogger RTD and the controller RTD have some discrepency at high temperatures)
Hold time = 51.5 hours (was 56, but I had neglected the ramp up time
Ramp down rate = 100 °C per hour

Additional annealing run after ENG_Labs/263 with longer duration to hopefully yield improvements to absorption.

Witness RTD observed a 497.1 °C overshoot and 14.5 °C offset from controller RTD. These parameters were consistent with the elog entries all entries, particularly the shorter duration ENG_Labs/263. See attached image of the temperature profile (.xlsx file is source document).

Optic is now with Liyuan in RTS for recharacterization after anneal.

SN1009 (80 mm witness sample) was annealed between 28 and 31January 2022 - used the large furnace in Downs 221, atmosphere was air, used glass petri dishes to protect optic (from Gabriele and CRiMe). Start time was 17:58 Pacific, and sample was removed at 8:30 am on Monday after a full weekend's cooldown.

Controller parameters:

Ramp up rate = 100 °C per hour
Hold temp = 478 °C (To avoid any unintended over-temperature due to overshoot or steady state offset - the datalogger RTD and the controller RTD have some discrepency at high temperatures)
Hold time = 10 hours
Ramp down rate = 100 °C per hour

Additional annealing run after ENG_Labs/261 and ENG_Labs/262 at higher temperature to hopefully yield improvements to absorption.

Witness RTD observed a 497.2 °C overshoot and 14.6 °C offset from controller RTD. These parameters were consistent with the elog entries ENG_Labs/253, ENG_Labs/254, ENG_Labs/260, ENG_Labs/261, and ENG_Labs/262. See attached image of the temperature profile (.xlsx file is source document).

Optic is now with Liyuan in RTS for recharacterization after anneal.

SN1009 (80 mm witness sample) was annealed between 25 and 26 January 2022 - used the large furnace in Downs 221, atmosphere was air, used glass petri dishes to protect optic (from Gabriele and CRiMe). Start time was 17:48 Pacific, and sample was removed at ~17:30 Pacific on the next day.

Controller parameters:

Ramp up rate = 100 °C per hour
Hold temp = 400 °C
Hold time = 10 hours
Ramp down rate = 100 °C per hour

Additional annealing run after ENG_Labs/260 at higher temperature to hopefully yield improvements to absorption.

Witness RTD observed a 421.1 °C overshoot and 14.5 °C offset from controller RTD. These parameters were consistent with the elog entries ENG_Labs/253, ENG_Labs/254, and ENG_Labs/260. See attached image of the temperature profile (.xlsx file is source document).

Optic is now with Liyuan in RTS for recharacterization after anneal.

SN1009 (80 mm witness sample) was annealed between 19 and 20 January 2022 - used the large furnace in Downs 221, atmosphere was air, used glass petri dishes to protect optic (from Gabriele and CRiMe). Start time was 18:28 Pacific, and sample was removed at 17:50 Pacific on the next day.

Controller parameters:

Ramp up rate = 100 °C per hour
Hold temp = 300 °C
Hold time = 10 hours
Ramp down rate = 100 °C per hour

Witness RTD observed a ~20 °C overshoot and ~13 °C offset from controller RTD. These parameters were consistent with the elog entries ENG_Labs/253 and ENG_Labs/254. See attached image of the temperature profile (.xlsx file is source document).

Optic is now with Liyuan in RTS for recharacterization after anneal.

[Stephen, Dean]

Aaron's past experience at Cryo_Lab/2563 is familiar to other LIGO users of the Lista tool chests. Occaisionally the mechanism which keeps the remaining drawers closed while a single drawer is open can lock all drawers. Dean brought to my attention that the Downs 228 chest was apparently locked. The key was nowhere to be found. Here's how we solved the problem:

1. I remembered Aaron's past experience and searched the elogs for "lista" until I found it.
2. Dean and I tried to perform the maneuver described at Aaron's link, but we were using flimsy stock that didn't seem to allow us to get the needed leverage.
3. I called the local Lista distributer (DMARK, 562.799.9010) and received an email including break-in instructions (Attachment 1, Attachment 2).
4. To expand upon the attached instructions, here are a few points of emphasis:

• Dean and I used a 1/4" x 1" x 36" aluminum strip to push straight forward on the C Channel.
• A flashlight could be used to ensure alignment to the C Channel if feel wasn't enough.
• Lifting a drawer was necessary to create a large enough gap (Attachment 3).
• Once we were successfule we removed a drawer to show how we had pushed (Attachment 4).

The key was found in the upper drawer and placed atop the chest.

[Stephen]

Ref. D1400331-v8 Item 48 - new high voltage feedthrough D2000585 protrudes along axis and requires protection.

Constructed simple connector guard for a 6" conflat on TMDS, with the following materials:

 - Stainless 304 sheet, 4" x 36" cut to length (a little long since I initially thought the conflat was 6.5" OD, but intended length is 18.7" for the 18.8" diameter) - p/n McMaster 1421T63

 - Stainless worm drive clamp - p/n McMaster 5682K22

[Stephen]

WIP placeholder

Ref. T2100351 instructions, plus email exchange indicating available media sizes.

Ref. FRS Ticket 20562 for shipment details.

[Stephen]

WIP placeholder

Simple machining operation setup and executed in Downs 228. Taking notes for future replication, and to drop the Photo Album somewhere useful.

Also thought this log would be helpful to communicate that we are able to quickly knock out simple mounts and mods like this in house.

 - Used Rotary Table for uniform circular cutting path; bolted down with 1/2" T-nuts and translated mill table to center ID of Rotary Table with edge finder. See Attachment 1 (more images in above photo album).

   --> 8" diameter Rotaty Table was a little too big for a standard end mill as the mill spindle is only offset from the turret by about 5 inches. There was not enough travel range in the direction toward the turret to reach the 40 mm radius from the Rotaty Table center. Could have cut in a different direction, but I didn't want to be caught later so I shifted to a larger radius cutter. While I was figuring this out, I managed to shear off one of the handles for locking down the Rotary Table during cutting - oops!

   --> Originally intended cutter was a .5" end mill, but I shifted to a 90 degree face mill for the extended radius given the above issue. I didn't feel too guilty about cutting the corners with the face mill, as the optic will have bevels and the acetal/delrin was soft.

 - I attempted to measure the 75mm diameter bore, and found the radius was larger by ~1mm. I then attempted to make a minimum 81mm diameter bore to host the 80mm optic, and overshot by a bit ( < 1mm ).

 - I elected to go for a greedy cut, creating a counterbore of the 75mm bore at an intermediate bore depth. This was an attempt to retain the 75mm bore function along with the new 80mm bore, and to fix either bore with the existing set screw. Liyuan verified that the new 80mm bore still behaves. So far, so good.

Imaging effort of coupons collected from LMA coating chamber panels.

uncoated_A_01 = area where coating delaminated during coupon cutting, near angled edge.

SN1535 was annealed between 07 and 08 September 2021 - used the large furnace in Downs 221, atmosphere was air, used glass petri dishes to protect optic (from Gabriele and CRiMe).

Controller parameters:

Ramp up rate = 100 °C per hour
Hold temp = 300 °C
Hold time = 10 hours
Ramp down rate = 100 °C per hour

Witness RTD observed a ~21 °C overshoot and ~14 °C offset from controller RTD. These parameters were consistent with the elog entry ENG_Labs/253. See attached image of the temperature profile (.xlsx file is source document).

Optic is now with Liyuan in RTS for recharacterization after anneal.

SN0932 was annealed between 02 and 03 September 2021 - used the large furnace in Downs 221, atmosphere was air, used glass petri dishes to protect optic (from Gabriele and CRiMe).

Controller parameters:

Ramp up rate = 100 °C per hour
Hold temp = 300 °C
Hold time = 10 hours
Ramp down rate = 100 °C per hour

Witness RTD observed a ~22 °C overshoot and ~14 °C offset from controller RTD. See attached image (.xlsx file is source document).

Optic is now with Liyuan in RTS for recharacterization after anneal.

Luis, Chub, Calum, Jordan, Dean, Rich

Today we filled neon into the new enclosure (Dxxx) that's destined for use with the A+ filter cavity length and alignment detector, plus the new DCPD preamplifiers.  The goal is to do a neon accumulation test over in the 40m lab.

Here is some related information:

1. The enclosure, lid, Helicoflex gasket, A286 10-32 SHCS bolts (used 20), S5 titanium washers (used 38*), S5 titanium nuts (used 20) were all cleaned and baked in the 40m bake facility by Jordan as an initial condition. * there were two holes where the washer would not fit under the head of the SHCS
2. We had on hand:
   1. Fresh bottle of neon plus hoses and regulators (loosen the regulator knob for minimum pressure, tighten the knob for more pressure to load)
   2. Torque wrench
   3. Allan adapters for torque wrench to go into SHCS
   4. 3/8 inch spanner to hold nuts
   5. Fresh glove bag
   6. Vacuum pump plus hoses
   7. Kapton tape to seal hose ports
   8. Measuring tape to judge how much volume of neon we used
   9. iPad to take pictures as we went
   10. Big adjustable wrench and allen key to change out regulator on neon bottle
   11. Circuit board to install inside
   12. Ribbon cable to attach the circuit board to the inner wall of the enclosure (need strain relief design to be sure these connectors don't fall off)
3. Here's what happened:
   1. Luis and Rich staged all the stuff in the clean room in the jitter lab
   2. We put the internal circuit board into the enclosure
   3. We plugged in the ribbon cable but had a bit of difficulty with putting the strain relief screws into the connectors (need a different setup here).  We ended up using some 4-40 screws in the connector on the wall of the enclosure, plus some zip ties to anchor down the connector to the PCB
   4. We didn't have any shorting plugs for the external connectors to avoid ESD damage, so we were careful, but no guarantees.
   5. We placed the gasket in its groove, then placed the lid on top of the enclosure.  Before tightening the bolts at all, we put a rolled up lint free cloth between the lid and the enclosure body so the neon had access to the inside of the enclosure while filling
   6. We put the allen adapters and 3/8 inch wrench into the glove bag
   7. We put the enclosure plus lid and gasket into a glove bag and rolled up as much of the bag as we could while still allowing room to get our hands into the access ports
   8. We added the vacuum hose and neon hose into the ports on the glove bag and taped them closed.
   9. We evacuated the bag with the vacuum pump, and then filled the bag with neon to a bag volume of approximately a 24-inch sphere.
   10. We removed the lint free cloth, then blew more neon into the enclosure to be sure it was filled well.  At this point, we were not thinking that neon was lighter than air.  Our first potential mistake.
   11. We snugged down the bolts and then removed the enclosure from the bag.  
   12. We then went off to lunch (our second mistake) and came back later to do the final torquing.
   13. When we returned, we realized that we now didn't know how much neon may have diffused from the interior of the enclosure, thus the experiment was uncertain.
   14. We proceeded anyway, and found torqued the bolts initially in a star pattern to 30 inch-pounds.
   15. After seven loops, (the second of which we abandoned the star pattern as it was too hard to keep our heads straight) we were at metal to metal on the flange surfaces, and could no longer rotate the bolts at 30 inch pounds.

We are chalking our inconclusive results up to experience, and starting again tomorrow with a fresh gasket.  We will be sure to account for the boyancy of neon in our fill method, and to rig a better way of flushing the interior of the enclosure with neon.

StephenA, 20 April 2021

Finished integrating the RTS Microscope Mount Assembly for the Keyence VH-Z250T lens (D2000085 WIP).

Feature description:

• Lens assembly may be fully connected to microscope, then attached to the mount.
• Easy on/off by passing lens assembly upward on shaft, then tightening thumb screw.
• Locking shaft collars are added for security, once the lens is in the final position on the shaft and the thumb screw has been tightened
• Position of lens assembly is repeatable in height and rotation.
  • Lens shaft mount (affixed by single thumb screw) registers in height and rotation against a flats cut into the vertical shaft. This provides registration of rotation about shaft axis.
  • Shaft is affixed to cantilever arm using shaft mounting blocks, including one with a set screw registering the rotation of the shaft with respect to the structure.
• Lens shaft height and lens height may be adjusted independently to a large range of positions, using a series of thumbscrew flats and a continuous shaft registration flat.
• Translation stage (used to focus microscope) has a hard stop in the direction toward the optic surface.

Overview of procedure for assembling the mount:

1. Cantilevered aluminum extrusion arm is preassembled to interface plates on an optical table. Interface plates should be spaced appropriately for the destination breadboard - the spacing on a one inch grid can be confirmed on an arbitrary optical table, but the layout should be confirmed with measurements of the application.
2. Shaft interface plates are preassembled to arm at a length along the arm that is appropriate for application.
3. Translation stage may be preassembled to arm, or mounted in situ. Translation stage free plate is slid out of the way to access 1/4-20 clearance holes used to affix translation stage base plate to the aluminum adapter plate.
4. Arm should be mounted to application at this stage.
5. Shaft should be mounted to translation stage in situ, via the below process.
   1. A set screw through the base of one of the shaft mount blocks is driven into the shaft's continuous upper flat, registering the shaft's rotation. The shaft should be clamped fully on the base, with the set screw meeting the flat - needs some slight loosening of the upper clamp to attain the correct rotation.
   2. The shaft is lightly clamped into the second base, with roughly the correct alignment and spacing, which are
   3. The mount bases are placed on the translation stage, and adjustments are made with the bases gently loosened to align to the vertically-held shaft and interface to the tranlation stage threaded hole spacing.
      1. If loosening any mount block clamps, the shaft must be held to prevent a sudden drop!
   4. Overall shaft height is set by the position of the mount blocks along the shaft. Once the rotation-registering set screw is in place, shaft height may be adjusted by loosening the mount block clamps, with the mount block bases still on the translation stage.
6. Confirm height of shaft provides clearance from optic (check for interference every time!)
7. Add upper shaft clamp to provide a third clamping location and vertical stop.

Overview of procedure for installing the microscope:

1. Bring the microscope lens assembly upward onto the shaft from underneath.
2. Tighten the thumb screw into the correct flat, currently the second from the bottom.
   1. Helps to make sure the thumb screw is just outside of the ID of the mount when you start the installation, so that you can tell when the thumb screw has extended into the flat and past the OD of the shaft.
   2. I prefer to turn the thumb screw 2 turns, then gently lower the thumb screw into contact with the bottom surface of the flat. This provides a height registration and constraint for the lens assembly. Once I feel the lens assembly resting on the flat of the shaft, I then tighten the thumb screw into the vertical surface of the flat and lock in the position.
   3. Hold the lens assembly by the main body with one hand during this operaiton, to avoid dropping the lens
3. Add the bottom shaft collar, typically stored loose above the permanent top shaft collar, to provide a redundant vertical height restraint.
4. Use the translation stage to make any final height adjustments required to bring the optic into position under the microscope and avoid interference.
5. Remove lens cap only when ready to bring the optic into position!

Images of mount in various states:

1. Mount ready to host microscope lens assembly - IMG_8613
2. Array of flats used to host the lens assembly's thumbscrew (we currently are mounted in the second from bottom flat) - IMG_8614
3. Tightening of thumb screw, from similar POV to previous images (slightly higher zoom) - IMG_8615
4. Lens assembly mounted and fully secured to mount - IMG_8617
5. Overview image of lens assembly in mount; taken before fully secured, as lower shaft clamp is missing - IMG_8616
6. Microscope hosted on small wire cart, in corner adjacent to RTS table - IMG_8467

Regina's problem statement:

 I attached examples of two measurements I got and wanted to know if these look reasonable. I took 6 measurements total, and I attached the first and last measurements. The graph on the last page is a picture of the weighting step for reference.

I didn't see significant ring down in all my measurements. Is this to be expected? I thought since the baffle is now rigidly mounted, the vibration should go almost to zero. I was also getting some low amplitude noise throughout the entire frequency domain that didn't show up in the first couple measurements I took. I tried to reset the vibrometer like you mentioned but they were still present. Is this a problem?

Stephen's reply:

1) Vibrometer may need a higher diffusivity surface to improve signal level.

Replying to your absence of ring down in your measurements - I agree that it looks like the vibrometer output is not behaving well, for one reason or another. In the freely suspended case, I was thinking this was due to large yaw and pitch motion causing high signal variation. Given that the symptom occurs when the baffle is fixed, I think the likeliest reason is the low signal, due to the low scatter and highly specular surface finish of this baffle (aka shiny). One way to troubleshoot would be to attach a compliant, diffusely reflecting material to the surface - think a small square of the adhesive-coated part of a Post-It note, for example - then tune the focus of the vibrometer and see if the vibrometer's signal level bar improves. If the signal level improves, take a hammer-excited measurement, and see if you see any ring down. If this behaves as you might expect, you could generate mode shape data with your excitation roving around the surface of the baffle while your response is fixed - just one baffle point would need your diffuse Post-It square (I might go with a central, or near central, location).

2) Test Article is not well understood, so try measuring something that has been characterized before.

If you try playing with the diffusivity and focus but the signal level doesn't improve, or if you don't see any ring down still, try pointing the vibrometerat the suspension cage and exciting the suspension with the hammer - that should give some real signal regardless of the precise setup, and if that gives similarly mystifying results, let me know and we can think a little harder about what might be going on. I feel pretty confident that between these two tests, you will find an answer.

3) Add another transducer (ie. a witness accelerometer) for comparison.

Another way to support your understanding of your setup (and a good practice) would be to mount the accelerometer to the suspension cage, adjacent to the baffle mounting brackets, or even to the mounting brackets themselves. This accelerometer would supply a witness to the low frequency resonances of the cage, which you may excite during your measurements, and might also provide some insights to the baffle panel resonances (rigid coupling with lower modal mass = smaller vibrations, but likely still above the noise floor of the accel) supporting your eventual successful vibrometer measurements.

4) Notes about mounting an accelerometer.

Mounting would involve collecting a ~[1mm x 1mm x 1mm] chunk of beeswax, spreading the beeswax onto the face of the accelerometer opposite the cable (I like to press it with the outer, flat-ish surface of my thumb nail to spread), and pressing the beeswaxed face onto a flat surface - think a 5 second push with all of your arm strength, which should create a thin layer with plenty of tackiness to hold the accel in any orientation. If it doesn't seem like it could hold for a day, then you might need more beeswax, or more force to create that thin layer. Note: the main way that an accel can go from useful to not is to experience a shock event, so I would recommend that you use some kapton tape to affix the accelerometer cable to the suspension cage - this will strain relieve your cabling and provide a fall restraint, and the potential for the cabling to influence the measurement is minimal here because it is remote from the baffle.

LHO BRDs:

I didn't observe frequency drifts during the month of assembly and monitoring in the Optics Lab. This is not expected from our experiments in the Modal Lab, but it makes the preparation for the sites BRDs easier.

BOUNCE: In anticipation to the frequency drifts, I had tuned the BRDs on the lower side of the target frequency. But the tuning didn't drift so I changed the masses last week for the bounce mode in order to be in the 1% target. The jumps in the curves below are due to retuning (on November 5th for BRD1, on November 20th for the other ones).

Roll: I didn't retune the Roll modes after assembly on October 20th. In the last days, I was experimenting with different ways to excite them (see pictures attached), so this is probably the cause of the slight drifts that we see.

This morning I handed off the parts for the 5 LHO BRDs to Bob Cottingham at LLO for Clean&Bake (https://ics.ligo-la.caltech.edu/JIRA/browse/clean-10214)

The parts for each BRD are in separate containers (see pictures attached).

Here are the masses of each component in order to reassemble the BRDs after C&B:

Stephen A, 2020 Nov 19

Ordered and received PO 75-S492380 including threaded rod and nut with 2"-12 thread.  These items are under consideration for A+ FC Tube Support Stand, particularly for use in weldment D2000445. Some observations:

• Thread area seems very small, nuts seem very large - wonder how strong the interface is.
• Pitch seems cumbersome - minutes may be necessary to install a nut in the middle of the thread.
• External thread appears to have some small damaged areas. Thread of nut can run over these areas, but with increase in friction.
• No apparent wobble or loosness of nut due to fit.
• Nut appears to have a oily coating applied to the outer surfaces, but not to internal threads.

Also ordered were two McMaster offerings which could be used for rust inhibiting conversion coatings (formulations appear to be based on phosphoric acid - more could be learned by investigating specific products). Potential workflow for experimenting:

1. Learn about the operating instructions for the specific product
2. Apply the coatings to 1 nut each (preclean needed for outer surfaces?)
3. Apply the coatings to different regions of the threaded rod

This experiment would allow us to learn about how the conversion coatings may work and behave.

See attached photos and video for more insights.

The 5 BS BRDs for installation at LLO are now assembled and tuned in the LLO Optics Lab. The target frequencies are 16.846 Hz and 24.672 Hz (measurements from A. Effler, I will post an alog in the LLO logbook about it).
As per the LHO ones, I tuned them at lower frequencies (-1 or -2%) in order to anticipate the frequency drifts.

For the LHO & LLO bounce modes and for LLO roll modes, I had to put two copper blocks per end at the blade tips in order to reach the target frequency.

There are several factors to take into account:

1. The measured mass for each type of the copper mass is lighter than what was expected from the design D1500429-v4 (about 0.2 to 0.3 g difference, see table in figure 2)
2. Somehow I have to use heavier masses than expected from the experiments at CIT (between 0.7 and 1.5 g, see below)

* Extrapolated from the k CIT experimental k.

I would have expected smaller variations in the spring constant.

The resulting masses are:

• H1 Bounce: lightest bounce type (type 8, ~8.6g) + spare mass of 0.595g + washer+screw
• L1 Bounce: heaviest bounce type (type 14, ~8.8g) + spare mass of 0.595g + washer+screw
• H1 Roll: heaviest roll type (type 7, ~6.4g) + washer+screw
• L1 Roll: heaviest roll type (type 7, ~6.4g) + spare mass of 0.55g + washer+screw

Even if the mass kit had the expected weight, I would have not been able to build the BRDs with the masses from the kit (or use several washers of 0.1g).

The EDTpdv framegrabber is unaccessible following a security update to the HWS computer. The lspci command shows the EDT frame grabber card as a PCI device but the initcam code no longer can connect to it. 

HWS code was backed up to GIT.

Tried updating EDT software to fix this but didn't work. After exhausting options, I'm going to reinstall the OS and try installing the EDT drivers again. Going to try to install Ubuntu 20.04 first (currently running 14.04).

The 5 BS BRDs for installation at LHO are now assembled and tuned in the LLO Optics Lab. The target frequencies are 17.79 Hz and 26.06 Hz (ref alog 49643).

The masses I had to use for the Bounce mode are slightly heavier than I was expecting (above 10.10g instead of 9.90g). The masses for the Roll mode are in target. I deliberately tuned the BRDs to lower frequencies (between -1% and -2% below the target) to anticipate the drift that shifts the frequencies to higher values. After 2 days, the drifts seem lower than was previoulsy observed at CIT (about 0.1% per day compared to 0.5% per day) with some of the BRDs exhibiting no drift at all. That might be good news? Monitoring will continue over the next weeks.

The Q values fluctuate from measurement to measurement, but they are essentially close to 100.

I am using the LLO B&K vibrometer kit, with an older version of the software that Stuart help me to setup, to measure the resonant frequencies. The air flow from the flow bench is currently off.

https://services.ligo-la.caltech.edu/FRS/show_bug.cgi?id=15312

Basis structural analysis was completed on models of the V5, V6, and a simple rectangular version of the BS BRD blades. The modesl were simplified to remove the glue layers. The models include stress analysis for individual layers of the blades, stress analysis for the entire blade, and a linearized stress analysis to examine stress discontinuties within the cross-section of the blade. The stresses analyzed include equivalent, maximum principle, and normal stress. The total deformation was also examined in the models. 

There is also attached an excel summary of the results of the models. 

The initial resuts of these models suggest that there is increased structural weakness in the V6 blade as opposed to the V5 blade. However, the results do not match with theorhetical stress analysis for the blades, so further analysis must be completed to refine the accuracy of the models. 

Right after tuning the BRDv5 9 and 10 (see elog 238), I installed them on the BS and measured the BS transfer function.

In figure 1, there are two consecutive measurements of the roll transfer function. The measurements are very close in time (~1 hour). However, we can see a large difference in the measured Q (lower than a factor 2). It is due to a change of settings in the power spectrum analyzer. First measurement is with auto range OFF and second measurement is with autorange ON. We can see a spike at 24.64 Hz in the blue curve. That corresponds to the moment I changed the settings. Edit: Rich A. just explained to me that the "autorange ON" setting isadjusting the gain as a function of the input voltage it is seeing. THerefore it must be used at the beginning of the experiment to select the gain and chek the noise floor and be turned OFF during measurements.

However, the BRDs are in tune for the roll mode.

Similarly, I measured the bounce mode right after installation (see figure 2) with the auto settings on. The Q of the peak is high compared to the measurements for the other BRDs. Could it be related to the setting change once again? Yes, I have to remeasure the mode.

For reference, please find the description of the current installation in the drawing attached.

Today I removed the BRD5_v5 and BRD6_v5 from the BS suspension, after their 6 months stay.

I measured their tuning right after. The identification of the BRD is not visible (it is written on the blade but hidden in the mount). So I just assigned a new name to the BRDs.

The measurements below confirm that the BRDs are still within range(+/-1%) after 6 months.

=================================

BRD5a_v5 - Bounce Mode

Tuning is 0.1%

BRD5a_v5 - Roll Mode

Tuning is 0.4%

================================

BRD6a_v5 - Bounce Mode

Tuning is 0.8%

BRD6a_v5 - Roll Mode

Tuning is 0.6%

BRD9_v5 and BRD10_v5 were remeasured and tuned yesterday (see elog 235).

I double checked the tuning right before installing the BRDs on the BS. Only BRD10 Roll mode was out of the 1% range (F = 24.05 Hz, too low), so I retuned it.

For reference, the final tuning is:

=================================

BRD9_v5 - Bounce Mode

Tuning is 0.2%

BRD9_v5 - Roll Mode

Tuning is 0.4%

================================

BRD10_v5 - Bounce Mode

Tuning is 0.1%

BRD10_v5 - Roll Mode

Tuning is 0.3%

====== Roll mode

Here is a summary of the BS roll mode survey with BRD5_v5 and BRD6_v6 attached to the suspension for 6 months.
Details of the measurements are attached in the spreadsheet.

The measured transfer functions over time are shown in figure 1. We observed two peaks in the data. This is in agreement with our model if the tuning if the BRD is within 0.1% of the BS roll mode (see T1900846).

• Trend .  The mean frequency is Hz. The maximum excursion is +% and the minimum is -%.  
• The Q of the mode is varying from to. Correlation with the frequency variations.

Therefore it seems that the bounce damping is pretty stable over 6 months. We didn't analyze correlations of the variations with environmental factors in the lab.

Measurements after taking off the BRD from BS:

Recall that pre-installation measurements were: 

====== Bounce Mode

Here is a summary of the BS bounce mode survey with BRD5_v5 and BRD6_v6 attached to the suspension for 6 months.
Details of the measurements are attached in the spreadsheet.

The measured transfer functions over time are shown in figure 1. We observed a single peak in the data. This is unexpected from our model.

• There is no trend in the value of the resonant frequency.  The mean frequency is 16.660 Hz. The maximum excursion is +0.4% and the minimum is -0.2%.  
• The Q of the mode is varying from 60 to 260, with no obvious correlation with the frequency variations. The maximum Q = 260 corresponds to a measurement with a lower amplitude of excitation (see elog xxx).

Therefore it seems that the bounce damping is pertty stable over 6 months. We didn't analyze correlations of the variations with environmental factors in the lab.

Measurements after taking off the BRD from BS:

Recall that pre-installation measurements were:

Constructed and tuned the BRD9 and BRD10 V5. The masses on each BRD were:

In the attached excel spreadsheet are the measured frequencies of the BRDs before and after tuning the dampeners. The BRDs were tuned to be with +/- 1% of the ideal value for the dampeners. These frequencies are 16.69 Hz for the bounce mode and 24.34 Hz for the roll mode. Also, the change in frequency over this week-long process was recorded to determine potential drift of the dampeners. 

Contributors

Stephen, Noah

Summary

It appears that Basler offers GigE cameras with over 2x improved sensitivity to the typical LIGO infrared laser wavelength. This camera is the "acA1300-60gmNIR" and it appears to be 2 to 5 times more sensitive at 1064 nm.

We do not have any of these cameras, and might want to consider getting our hands on one to evaluate its utility in lab settings (or perhaps even in site GigE camera installations).

Detailed Findings

As discussed in the Basler technical documentation, there are 3 different sensors that Basler packages into their cameras.

--> ref. https://www.baslerweb.com/en/vision-campus/camera-technology/nir-cameras/

"The NIR-optimized cameras with NIR-optimized 2 MP (CMV2000) and 4 MP (CMV4000) sensors from CMOSIS, or the 1.3 MP sensor (EV76C661) from e2V, still manage quantum efficiencies close to 40% in the 850nm range. Compared to non-NIR-optimized cameras, this represents a doubling of the sensitivity value at this wavelength."

Examining these sensors closer, the better QE at 1000 nm wavelength is from the 1.3 MP sensor (EV76C661) from e2V. This is notable because LIGO uses 1064 nm wavelength, and the highest QE reported in the datasheets is at 1000 nm.

The camera which uses this sensor is the "acA1300-60gmNIR" which is available in either C-mount lens interface, or CS-mount lens interface.

--> ref. https://www.baslerweb.com/en/products/cameras/area-scan-cameras/ace/aca1300-60gmnir/

Methods

Begin at a given camera's Basler webpage. See example below.

--> ref. https://www.baslerweb.com/en/sales-support/downloads/document-downloads/basler-ace-aca2000-50gmnir-emva-data/

Navigate to "Documents" tab and then to "EMVA Data". There are two attachments in this section:

• the overview pdf, which gives a rundown of the specs of each camera and the cameras using each sensor
• the sensor-specific pdf, which gives technical data from the tests collected for a number of articles of each sensor, which corresponds to the indicated sensor

By using the camera-specific pdf, you can identify the quantum efficiency at NIR wavelenghts up to 1000 nm.

Alternatively, if you know you want a specific sensor or specification, you can identify the cameras using the overview pdf, or using the Vision System Configurator

--> ref. https://www.baslerweb.com/en/products/tools/vision-system-configurator/#/selection/camera/

Next Steps

We'll use this log as a starting point to compile the resolutions, sensitivities, and any other parameters for each existing LIGO GigE camera and each possible improved camera.

We will also continue our work in identifying all of the necessary components that could help us construct a mobile setup which enables interchangeability of the various GigE cameras that are at our disposal (WIP).

Data is in attached excel file.

From January 14 to the 21, Bounce BRD 7's frequency drifted -2.68% which differes from the drift logged on January 14 which was 0.15% on the opposite direction. The Roll of BRD 7's frequency drifted -4.41% which is a big change from the previous logged drift of 0.06%.

The Roll side for BRD 7 on January 21 was much closer to the target frequency. It was logged as 24.36 Hz and the target is 24.34 Hz. The Bounce side was also logged as much closer to the target frequncy. The target is 16.69 Hz and the frequency logged was 16.80 Hz.

The Q factors for both the Roll side and the Bounce side have decreased from the previous entry. Roll decreased from 108 Hz to 100 Hz and Bounce decreased from 87 Hz to 79 Hz.

BRD 8's frequency was tested for the first time. Roll side's frequency was 24.57 Hz. Bounce side's frequency was 17.956 Hz. Roll side is close to the target frequency, but Bounce side is off by 1.26 Hz.

The length for the new copper masses will be computed.

To determine the best achievable Q as a function of the mistuning, we studied a simple model with 2 resonant masses (see elog 150). Now we have a model with 3 resonant masses (presented in elog 217, 219, T1900846).

• Factor 2:

As a reminder, in order to obtain the same transfer function with 2 masses model and the 3 masses model, we need to multiply the mass of the unique BRD by 2 in the model with 2 masses (see figure 1).

Here we assumed the Q of the standalone BRD is 110 and perfect tuning. The resulting Q of the two peaks is around 220. This is in line with the rule of thumb that states "for perfect tuning, the resultant Qs of the bounce and roll modes are approximately 2x the Q of the damper" (Norna's email). However, with the 3 masses model, the resonance of the BS corresponds to the "dip" in the transfer function. At this frequency, the Q value is exactly the Q of the damper. Therefore, there is no factor 2 for the BS mode.

• Detuning

%% Recalling here some results:

• m_B = 10 g → k_B = 110 N/m, 
• m_R = 7.3 g → k_R = 171 N/m

Mass ratio is therefore:

• μ_B = 10g/27.78 kg = 3.6e-4
• μ_R= 7.3g/12.90 kg = 5.7e-4

And we measured:

• Q_B ~ 100-110
• Q_R ~ 60-80

%%

In T1500271, Brett derives the best achievable Q of a damper for a given mass ratio:

Q = 1/(2*w1/w2*sqrt(3*mu(ii)/(8*(1+mu(ii))^3))); % from equation 12 in T1500271

Comparing these values to our blade v5 measurements for bounce and roll modes, we can see that the actual Qs for the standalone BRDs are a factor 2.5 higher than this ideal case (see figure 2). We therefore updated the study of elog 150 with the new 3 resonant masses model and the Qs of the standalone BRDs equal to 2.5 times the ideal Qs. The results are summarized in graphs 3 and 4. We can see that:

• The Q of the BS decreases with the increase of the mass ratio. Therefore, the Q of the bounce mode will be higher than the roll mode.
• The Q of the BS increases with the detuning. 1% mistuning allows to maintain the Qs below 200.
• The Q of the BRDs decreases with the increase of the mass ratio.
• The Q of the BRDs decreases with the detuning. At perfect tuning, the Q of the bounce mode is about 225.

So we could aim for a tuning of the BRDs within 1% of the BS resonant frequencies.

Overnight the Bounce mode of BRD7_v5 drifted 0.16% which is surprising if we compare it to the drift from the previous month which was lower and in the other direction. The Roll mode of BRD7_v5 drifted by 0.06% and also in the positive direction. As mentioned in elog 154 we want to tune the BRD to 16.69 Hz for Bounce and 24.34 Hz for Roll.

We tuned the bounce side at 0.25% from the target at 16.731 Hz. We noticed that the Q factor increased from 60 to 90 during the tuning. Could it be related to the tightness of the screw? 

We tuned the Roll side 0.07% from the target at 24.347 Hz. Again we see an increase in the Q factor to over 100.

Today we added the masses for the Roll of BRD 8:

4.043+2.351+screw= 7.293g