Sub-ASSY #7

Probably the best glued unit among the four.

Attachment #1: Mounting Block SN001

Attachment #2: PZT-Mounting Block bonding looks completely wet. Excellent.

Attachment #3: The other side of the PZT-Mounting Block bonding. Also looks excellent.

Attachment #4: Overall look.

Attachment #5: The mirror-PZT bonding also look excellent. The mounting block surface has many EP30-2 residue. But they were shaved off later. The center area of the aperture is clear.

Attachment #6: A small fracture of the mirror barrel is visible (at 7 o'clock).

Sub-ASSY #8

Probably the best glued unit among the four.

Attachment #1: Mounting Block SN007

Attachment #2: Overall look.

Attachment #3: Some fracture on the barrel visible.

Attachment #4: It is visible that a part of the PZT removed. Otherwise, PZT-Mounting Block bonding looks pretty good.

Attachment #5: The other side of the PZT bonding. Looks fine.

Attachment #6: Fractured PZT visible on the fixture parts.

Attachment #7: Fractured glass parts also visible on the fixture parts.

Attachment #8: MIrror bonding looks fine except for the glass chip.

Sub-ASSY #9

The most fractured unit among four.

Attachment #1: Mounting Block SN017

Attachment #2: Two large removals well visbile. The bottom right corener was chipped.

Attachment #3: Another view of the chipping.

Attachment #4: PZT-mounting block bonding look very good.

Attachment #5: Another view of the PZT-mounting block bonding. Looks very good too.

Attachment #6: Fractures bonded on the fixture.

Attachment #7: Front view. The mirror-PZT bonding look just fine.

Sub-ASSY #10

Attachment #1: Mounting Block SN021

Attachment #2: PZT-Mounting Block bonding looks just excellent.

Attachment #3: The other side of the PZT-Mounting Block bonding is also excellent.

Attachment #4: The mirror-PZT bonding also look excellent. Some barrel fracture is visible at the lower left of the mirror.

Apr 16, 2019
Borrowed two laser goggles from the 40m. (Returned Apr 29, 2019)
Borrowed small isopropanol glass bottole from CTN.

Apr 19, 2019
Borrowed from the 40m:
- Universal camera mount
- 50mm CCD lens
- zoom CCD lens (Returned Apr 29, 2019)
- Olympus SP-570UZ (Returned Apr 29, 2019)
- Special Olympus USB Cable (Returned Apr 29, 2019)

[Stephen, Philip, Koji, Joe]

Breadboard D1200105 SN06 was selected as described in eLOG 338. This log describes unwrapping and preparation of the breadboard.

Relevant procedure section: E1300201 section 6.1.5

Breadboard was unwrapped. No issues observed during unwrapping.

• Attachment 1: packaging of SN06.

Visual inspection showed no issues observed in breadboard - no large scratches, no cracks, no chipping, polished area (1 cm margin) looks good.

• Attachment 2: engraving of SN06.

Initially the breadboard has a large amount of dust and fiber from the paper wrapping. Images were gathered using a green flashlight at grazing incidence (technique typical of optic inspection).

PROCEDURE IMPROVEMENT: Flashlight inspection and Top Gun use should be described (materials, steps) in E1300201.

• Attachment 3: particulate before Top Gun, large face.
• Attachment 4: particulate before Top Gun, small face.

Top gun was used (with medium flow rate) to remove large particulate. Breadboard was placed on Ameristat sheet during this operation.

• Attachment 5: particulate after Top Gun

Next, a clean surface within the cleanroom was protected with Vectra Alpha 10 wipes. The breadboard, with reduced particulate after Top Gun, was then placed inside the cleanroom on top of these wipes. Wiping with IPA Pre-wetted Vectra Alpha 10 wipes proceeded until the particulate levels were acceptable.

Joe and Koji then proceeded with placing the breadboard into the transport fixture.

[Joe, Koji, Liyuan, Philip, Stephen]
Work done on 16.04.2019

Finishing assembly of transport box
Assembly worked fine except for the clamping structure to clamp the lid of the transport box to the bottom part.
It seemed that some of the plastic of these clamps became brittle during the baking. The plastic was removed and the
clamps where wiped clean. It appears that the clamps can't be locked as they should. Still the transport box should be fine
as the long screws will mainly clamp the two parts together.

Preparing the transport box to mount the breadboard
The lid of the the transport box was placed upside down and clamped to the table. All peak clamping structures where pulled back as far as possible.

Preparation and cleaning of the breadboard
We unpacked the breadboard and found lots of dust particles on it (most likely from the soft paper cover which was used). We used the ionized nitrogen gun
at 25 psi to get rid of the majority of particles and cross-checked with a bright green flash light before and after blowing. The second stage of cleaning was done
below the clean room tent and included the wiping of all surfaces. The breadboard was then placed into the prepared lid of the transport box and clamped with peak
screws.

Unpacking of the template
The previously cleaned template was unpacked while the last layer of coverage was removed below the cleanroom tent.

Template adjustment on the breadboard
All peak screws of the clamping structure of the template where removed. The template was placed onto the breadboard only seperated by peak spacers.
All peak screws have been inserted for horizontal clapming. A calipper was used to measure the distance of each edge of the template to the edge of the
breadboard. For documentation the labeled side of the bradboard (facing away from the persons on the pictures) of the upside down breadboard is defined to 
be the south side, continuing clockwise with west, north and east. First rough alignment was done by shifting the template on the breadboard and then the 
peak screws where used for fine tuning. The caliper values measured where:
North   C 8.32mm     E 8.52 mm     W 8.41 mm
East     C 8.08 mm
South   C 8.32 mm
West    C 8.02 mm
(E indicating east side position, W indicating west side position and C indicating center position)

[Stephen, Koji]

As mentioned in eLOG 331, either increased thermal cycling or apparent improvements in cured EP30-2 strength led to fracture of curved mirrors at unintended locations of bonding to the PEEK fixture parts.

The issue and intended resolution is summarized in the attached images (2 different visualizations of the same item).

Redline has been posted to D1600336-v3.

Drawing update will be processed shortly, and parts will be modified to D1600336-v4.

Notes on the OMC cavity alignment strategy

- x3=1.17 γ + 1.40 δ, x4=1.40 γ + 1.17 δ
- This means that the effect of the two curved mirrors (i.e. gouy phases) are very similar. To move x3 and x4 in common is easy, but to do differentially is not simple.
- 1div of a micrometer is 10um. This corresponds to the angular motion of 0.5mrad (10e-6/20e-3 = 5e-4). ~0.5mm spot motion.
- ~10um displacement of the mirror longitudinal position has infinitesimal effect on the FSR. Just use either micrometer (-x side).
- 1div of micrometer motion is just barely small enough to keep the cavity flashing. => Easier alignment recovery. Larger step causes longer time for the alignment recovery due to the loss of the flashes.

- After micrometer action, the first move should be done by the bottom mirror of the periscope. And this is the correct direction for beam walking.

- If x3 should be moved more than x4, use CM2, and vise versa.
- If you want to move x3 to +x and keep x4 at a certain place, 1) Move CM2 in (+). This moves x3 and x4 but x3>x4. 2) Compensate x4 by turning CM1 in (-). This returnes x4 to the original position (approximately), but leave x3 still moved. Remember the increment is <1div of a micrometer and everytime the cavity alignment is lost, recover it before loosing the flashes.

Suddenly something dirty emerged in the lab. What is this? It looks like an insulation foam or similar, but is quite degraded and emits a lot of particulates.

This does not belong to the lab. I don't see piping above this area which shows broken insulation or anything. All the pipes in the room are painted white.

The only possibility is that it comes from the hole between the next lab (CRIME Lab). I found that the A.C. today is much stronger and colder than last week. And there is a positive pressure from CRIME Lab. Maybe the foam was pushed out from the hole due to the differential pressure (or any RF cable action).

That is an expanding fire pillow, also known as firebrick.  It is used to create a fire block where holes in fire-rated walls are made and prevents lab fires from spreading rapidly to adjacent labs.  I had to pull cable from B254 to our labs on either side during a rather narrow window of time.  Some of the cable holes are partially blocked, making it difficult to reach the cable to them. The cable is then just guided to the hole from a distance.  With no help, it's not possible to see this material getting shoved out of the hole.  I can assure you that I took great pains not to allow the CYMAC coax to fall into any equipment, or drag against any other cables.   

[LiyuanZ, StephenA]

Downs B119

Summary: Beginning on 20 May 2019, two CM PZT assemblies were soaked in Acetone in an effort to debond the EP30-2 bonds between tombstone-PZT and between PZT-optic. Debonding was straightforward after 8 days of soaking. 24 hours of additional acetone soaking will now be conducted in an attempt to remove remnant EP30-2 from bonding surfaces.

Procedure: The assemblies were allowed to soak in acetone for 8 days, with acetone level below the HR surface of the optic. No agitation of the solution, mechanical abrasion of the bond, or other disturbance was needed for the bond to soften.

GariLynn contributed the glassware and fume hood, and advised on the process (similar to debonding of CM and PZT from OMC SN002 after damaging event). The equipment list was (WIP, more detail / part numbers will be gathered today and tomorrow):

• crystallizing dish (no spout, like a deep petri dish)
• curved lid
• wax sheet (to seal)
• acetone
• fume hood

Results: Today, 28 May 2019, I went to the lab to check on the optics after 8 days of soaking. Liyuan had monitored the acetone level during the first 4 days, topping up once on 24 May. All bonds were fully submerged for 8 days.

There were 2 assemblies soaked in one crystallizing dish. Debonded assemblies - ref OMC eLOG 328 for specified orientations and components:

PZT Assy #9 - ref. OMC eLOG 334 - M17+PZT#12+C10

PZT Assy #7 - ref. OMC eLOG 332 - M1+PZT#13+C13

PZT Assy #7 was investigated first.

• C13 was removed with no force required.
• PZT#13 was removed with no force required.
• EP30-2 remained at the bond surfaces and tracing the diameters of each bond on each of the 3 bonding surfaces of the PZT and tombstone - these components were returned to the dish to soak.
• No EP30-2 remained on the surface of the curved mirror - C13 was removed and stored.

A video of removal of C10 and PZT#12 from PZT Assy #9 was collected (See Attachment 8), showing the ease with which the debonded components could be separated.

• C10 was removed with no force required.
• A slight force - applied by gripping the barrel of the PZT and pushing with the index finger on the surface of the tombstone - was required to separate PZT#12 from M17,
  • likely due to excess glue at the barrel of the PZT
• EP30-2 remained at the bond surfaces and tracing the diameters of each bond on each of the 3 bonding surfaces of the PZT and tombstone - these components were returned to the dish to soak.
• No EP30-2 remained on the surface of the curved mirror - C13 was removed and stored.

Photos and video have been be added to supplement this report (edit 2019/07/08).

https://www.airscience.com/purair-flow-laminar-flow-cabinets

Here is a summary of the events of the last week, as they relate to EP30-2.

1) I lost the EP30-2 syringes that had been ordered for the OMC, along with the rest of the kit.

• Corrective action: Found in the 40m Bake Lab garbing area.
• Preventative action: log material moves and locations in the OMC elog
• Preventative action: log EP30-2 moves and locations in PCS via location update [LINK]
• Preventative action: keep EP30-2 kit on home shelf in Modal Lab unless kit is in use

2) The EP30-2 syringes ordered for the OMC Unit 4 build from January had already expired, without me noticing.

• Corrective action: Requested LHO ship recently-purchased EP30-2 overnight
• Preventative action: log expiration dates in OMC elog
• Preventative action: begin purchasing program supported by logistics, where 1 syringe is maintained on hand and replaced as it expires

3) LHO shipped expired epoxy on Thursday. Package not opened until Monday.

• Corrective action: Requested LHO ship current EP30-2 overnight, this time with much greater scrutiny (including confirming label indicates not expired)
• Preventative action: Packages should be opened, inspected, and received in ICS or Techmart on day of receipt whenever possible.

4) Current, unopened syringe of EP30-2 has been received from LHO. Expiration date is 22 Jan 2020. Syringe storage has been improved. Kit has been docked at its home in Downs 303 (Modal Lab) (see attached photo, taken before receipt of new epoxy).

Current Status: Epoxy is ready for PZT + CM subassembly bonding on Monday afternoon 23 September.

The following items are presently staged at the 40m Bake Lab (see photo indicating current location) (noting items broght by Koji as well):

1. Bonding fixtures, now modified with larger washers to constrain springs, and with modification from OMC elog 358.
2. Curved Mirrors and Tombstones as selected by Shruti in OMC elog 374.
3. PZTs as debonded from first iteration subassemblies (SN 12 and SN 13)
4. Epoxy-cure-testing toaster oven
5. Other items I can't think of but will populate later  =D

The following item is in its home in Downs 303 (Modal Lab)

1. EP30-2 epoxy (expiration 2020 Jan 22) with full kit (tracked in PCS via location update [LINK])

The 40m Bake Lab's Dirty ABO's OMEGA PID controller was borrowed for another oven in the Bake Lab, so I have had to play with the tuning and parameters to recover a suitable bake profile. This bake is pictured below (please excuse the default excel formatting).

I have increased the ramp time, temperature offset, and thermal mass within the oven; after retuning and applying the parameters indicated, the rate of heating/cooling never exceeds .5°C/min.

The ABO is controlled by a different temperature readout from the data logger used to collect data; the ABO readout is a small bead in contact with the shelf, while the data logger is a lug sandwiched between two stainless steel masses upon the shelf. I take the data logger profile to be more physically similar to the heating experienced by an optic in a gluing fixture, so I feel happy about the results of the above bake.

I plan to add the data source file to this post at my earliest convenience.

[Stephen, Shruti, Koji]

We worked on the gluing of the PZT sub-assy (#9 and #10) along with the designed arrangement by Shruti (OMC ELOG 374).

The detailed procedures are described in E1300201 Section 6.2 PZT subassembly and Section 7.3 EP30-2 gluing.

We found that the PZTs, which were debonded from the previous PZT sub assy with acetone, has some copper wires oxidized. However, we confirmed that this does not affect the conductivity of the wires, as expected.

The glue test piece cooked in the toaster oven showed excellent curing. GO SIGNAL

Stephen painted the PZT as shown in Attachment 1.

The fixtures were closed with the retaining plate and confirmed that the optics are not moving in the fixtures.

At this point, we checked the situation of the air-bake oven. And we realized that the oven controller was moved to another vacuum oven and in use with a different setting.

Stephen is going to retrieve the controller to the air bake oven and test the temp profile overnight. Once we confirm the setting is correct, the PZT sub assys will be heat cured in the oven.  Hopefully, this will happen tomorrow. Until then, the sub-assys are resting on the south flow bench in the cleanroom.

The 40m Bake Lab's Dirty ABO's OMEGA PID controller was borrowed for another oven in the Bake Lab (sound familiar? OMC elog 377), so I have had to play with the tuning and parameters to recover. This bake seemed to inadequately match the intended temperature profile for some reason (intended profile is shown by plotting prior qualifying bake for comparison).

The parameters utilized here are exactly matching the prior qualifying bake, except that the autotuning may have settled on different parameters.

Options to proceed, as I see them, are as follows:

1. reposition the oven's driving thermocouple closer to the load and attempt to qualify the oven again overnight
2. retune the controller and attempt to qualify the oven again overnight
3. proceed with current bake profile, except monitor the soak temperature via data logger thermocouple and intervene if temperature is too high by manually changing the setpoint.

Follow up on OMC elog 379

I was able to obtain the following (dark blue) bake profile, which I believe is adequate for our needs.

The primary change was a remounting of the thermocouple to sandwich it between two stainless steel masses. The thermocouple bead previously was 1) in air and 2) close to the oven skin.

Friday: [Stephen, Koji]

As the oven setting has qualified, we brought the PZT assys in the air bake oven.

Monday: [Stephen, Shruti, Koji]

We brought the PZT assys to the clean room. There was not bonding between the flexture and the PZT subassy (Good!). Also the bonding o at each side looks completely wetted and looks good. The package was brought to the OMC lab to be tested in the optical setup.

OMC PZT Assy Production Cure Bake (ref. OMC elog 381) for PZT Assy #9 and #10 started 27 September 2019 and completed 28 September 2019. Captured in the below figure (purple trace). Raw data has been posted as an attachment as well.

We have monitored the temperature in two ways:

1) Datalogger thermocouple data (purple trace).
2) Checking in on temperature of datalogger thermocouple (lavender circles) and drive thermocouple (lavender diamonds), only during initial ramp up.

Comments on bake:

• No changes were made to the tuning or instrumentation of the oven between the successful qualifying bake obtained on 26 September (ref. OMC elog 380). However, the profile seems to have been more similar to prior qualifying bake attempts that were less successful (ref. OMC elog 379), particularly as the oven seems to have ramped to an overtemperature state. I am a bit mystified, and I would like to see the oven tuning characterized to a greater extent than I have had time and bandwith to complete within this effort.
• The maximum datalogger temperature was 104 °C, and the duration of the soak (94 °C or higher) was 68 minutes. This was in contrast to a programmed soak of 2.5 hours and a programmed setpoint of 84 °C.
• The drive thermocouple did appear to be under-reporting temperature relative to the datalogger thermocouple, but this was not confirmed during the soak period. Neither thermocouple was calibrated as part of this effort.

This post captures the curing timeline followed by OMC PZT Assys #9 and #10.

Source file posted in case any updates or edits need to be made.

The following is the current status of the epoxies used in assembly of the OMC (excerpt from C1900052)

Re-purchasing efforts are underway and/or complete

• DONE
  • Masterbond EP30-2 currently located in Downs 303, Modal Lab (see image)
    • ( WILL EXPIRE JANUARY 2020 )
    • ( tracked using THIS PCS LINK https://services.ligo-la.caltech.edu/Inventory/history.php?recid=1582&invtype=cit_noncap )
  • Electronic Materials Inc Optocast 3553-LV procured via PCard, will arrive today 22 October
    • plan to track using PCS is WIP
• WIP
  • Epoxy Pax EP-1730-1 quoted and requisitioned, PO is WIP

[Stephen, Koji]

20 glass beamdumps were bonded at the 40m cleanroom.

Attachment 1: We had 20 fused silica disks with a V-groove and 40 black glass pieces
Attachment 2: The black glass pieces had (usual) foggy features. It is well known to be very stubborn. We had to use IPA/acetone and wiping with pressure. Most of the feature was removed, but we could still see some. We decided to use the better side for the inner V surfaces.
Attachment 3: EP30-2 expiration date was 1/22/2020 👍. 7.66g of EP30-2 was poured and 0.38g of glass sphere was added. Total glue weight was 8.04g
Attachment 4: Glue test piece was baked at 200F in a toaster oven for ~12min. It had no stickiness. It was totally crisp. 👍👍👍
Attachment 5: Painted glue on the V-groove and put the glass pieces in. Then gave a dub of blue at the top and bottom of the V from the outside. In the end, we mostly had the glue went through the V part due to capillary action.
Attachment 6: The 20 BDs were stored in stainless vats. We looked at them for a while to confirm there is no drift and opening of the V part. Because the air bake oven was not available at the time, we decided to leave the assys there for the room temp curing, and then later bake them for the completion of the curing.
 

[Koji, Jordan, Stephen]

The beam dumps, bonded on Fri 06 Dec 2019, were placed in the newly tuned and configured small dirty ABO at the Bake Lab on Fri 13 Dec 2019.

Images are shared and references are linked below

Bonding log entry - https://nodus.ligo.caltech.edu:8081/OMC_Lab/386

Bake ticket - https://services.ligo-wa.caltech.edu/clean_and_bake/request/992/

OMC Beam Dump - https://dcc.ligo.org/LIGO-D1201285

The beamdumps were taken out from the oven and packed in bags.

The bottom of the V are completely "wet" for 17 BDs among 20 (Attachment 1/2).

3 BDs showed insufficient glue or delamination although there is no sign of lack of rigidity. They were separated from the others in the pack.

Item lending as per Ian's request: Particle Counter from OMC Lab to QIL

The particle counter came back to the OMC lab on Aug 10, 2020

Check-in to the OMC lab to see the status. Nothing seemed changed. No bug. The HEPA is running normal. The particle level was 0.

Went into the HEPA enclosure and put a cover on the OMC. Because of the gluing template, the lid could not be close completely (that's expected and fine).

The IPA vector cloth bag was not dry yet but seemed expired (some smell). There is no stock left -> 5 bags to be ordered.

are there any measurements of the BRDF of these things? I'm curious how much light is backscattered into the incoming beam and how much goes out into the world.

Maybe we can take some camera images of the cleaned ones or send 1-2 samples to Josh. No urgency, just curiosity.

I saw that ANU and also some labs in India use this kind of blue/green glass for beam dumps. I don't know much about it, but I am curious about its micro-roughness and how it compares to our usual black glass. For the BRDF, I think the roughnesss matters more for the blackness than the absorption.

According to the past backscatter test of the OMC (and the black glass beamdump: not V type but triangular type on a hexagonal-mount), the upper limit of the back reflection was 0.13ppm. https://nodus.ligo.caltech.edu:8081/OMC_Lab/209

I don't have a BRDF measurement. We can send a few black glass pieces to Josh.

To spare some room on the optical table, I wanted to mount the two TFT monitor units on the HEPA enclosure frame.
I found some Bosch Rexroth parts (# 3842539840) in the lab, so the bracket was taken for the mount. This swivel head works very well. It's rigid and still the angle is adjustable.

https://www.boschrexroth.com/ics/cat/?cat=Assembly-Technology-Catalog&p=p834858

BTW, this TFT display (Triplett HDCM2) is also very nice. It has HDMI/VGA/Video/BNC inputs (wow perfect) and the LCD is Full-HD LED TFT.
https://www.triplett.com/products/cctv-security-camera-test-monitor-hd-1080p-led-display-hdcm2

https://www.newegg.com/p/0AF-0035-00016

https://www.bhphotovideo.com/c/product/1350407-REG/triplett_hdcm2_ultra_compact_7_hd_monitor.html

The only issue is that one unit (I have two) shows the image horizontally flipped. I believe that I used the unit with out this problem before, I'm asking the company how to fix this.

The image flipping of the display unit was fixed. The vendor told me how to fix it.

- Open the chassis by the four screws at the side.
- Look at the pass-through PCB board between the mother and display boards.
- Disconnect the flat flex cables from the pass-through PCB (both sides) and reconnect them (i.e. reseat the cables)

That's it and it actually fixed the image flipping issue.

See this entry: https://nodus.ligo.caltech.edu:8081/40m/15642

Thorlabs' powermeter controler + S401C head was lent from OMC Lab. Returned to OMC Jul 15, 2022 KA

https://nodus.ligo.caltech.edu:8081/SUS_Lab/1856

I helped to complete the 5th OMC Transport Fixture. It was built at the 40m clean room and brought to the OMC lab. The fixture hardware (~screws) were also brought there.

FEMTO DLPCA200 low noise preamp (brand new)

Keithley Source Meter 2450 (brand new) => Returned 11/23/2020

were brought to the OMC lab for temporary use.

https://nodus.ligo.caltech.edu:8081/QIL/2522

OMC Unit 4 Build Machined Parts are currently located in Stephen's office. See image of large blue box from office, below.

Loaned item D1100855-V1-00-OMC08Q004 to Don Griffith for work in semi-clean HDS assy.

This includes mass mounting brackets, cable brackets, balance masses, etc. For full inventory, refer to ICS load Bake-9527 (mixed polymers) and Bake-9495 (mixed metals).

Inventory includes all items except cables. Plasma sprayed components with slight chipping were deemed acceptable for Unit 4 use. Cable components (including flex circuit) are ready to advance to fabrication, with a bit more planning and ID of appropriate wiring.

Item loan: SRS LCR meter SRS720 borrowed from Downs. The unit is at the 40m right now for testing with an excelitas PD. Once it is done, the setup will be moved to the OMC lab for testing the high QE PDs

Attachment 1: System diagram. The reverse bias voltage is controlled by DS335. This can produce a voltage offset up to 10V. A G=+2 opamp circuit was inserted so that a bias of up to +15V can be produced. The capacitances of the photodiodes were measured with SR720 LCR meter with a probe. DS335 and SR720 were controlled from PC/Mac via serial connections.

Attachment 2: Overview

Attachment 3: How was the probe attached to the photodiode under the test

Attachment 4: The bias circuitry and the power supply

Attachment 5: G=+2 amp

Measurement result:

The capacitance at no bias was 460~500pF. This goes down to below 300pF at 1.0~1.5V reverse bias. At maximum +15V, the capacitance goes down to 200~220pF.

On this opportunity, the capacitances of a couple of Excelitas C30665 photodiodes were measured. In Attachment 2, the result was compared with one of the results from the high QE PDs. In general the capacitance of C30665 is lower than the one from the high QE PDs.

More explicit insights into the inventory for the Unit 4 build. Image of inventory included below.

Machined Parts:

• New fabrication = Contents of Storage-11112 are consistent with upgrade ECR.
• Old leftovers = Storage-9482 and Storage-9483 .

Cable Components:

• Hughes Circuits made us Kapton flex circuits. These have not been processed in any way.
• Rich had supplied a spool of Gore 4-conductor in-vacuum wire (see below image). I returned the sppol for Rich but it is living in Downs and available for use.
• PEEK cable ties were damaged during bake, and will be replaced by SYS inventory.

Retrofit/Repair Capabilities:

• Aluminum reinforcement brackets D1600316
• Glass reinforcement brackets (Edmund Optics 45-072 and 45-071)

ref: E1900034 and other associated documents.

I've cleared the small optical table and wondered how to move it out of the room. Fortunately, the north side of the big table had wide enough clearance and let the 36" wide table go through. This was easy without moving other heavy stuff.

From here to the door, a bit of work is required. A possibility is to roll the laser blocking wall to the south side of the big table. This will require moving the shelving in the entrance area but it's not a lot of work compared to disassembling a part of the wall.

If this does not work somehow, we will consider removing the last panel of the wall and it will definitely allow the table to get out from the door.

The table width was an inch too large compared to the door width. We need to tilt the table and it seemed too much for us. Let's ask the transportation for handling.

Photo courtesy by Juan

- The lab is chilly (18degC)

- Cleaned the lab and the optical table a bit so that the delicate work can be done. The diode test rig (borrowed from Downs - see OMC ELOG 408 and OMC ELOG 409) was removed from the table and brought to the office (to return on Monday)

- The rack electronics were energized.

- The OMC mirrors in use were returned to the cases and stored in the plastic box.

- The optical table was also cleaned. Removed the old Al foils. The table was wiped with IPA

- The OMC #4 was moved to the other part of the table, and then OMC #2 was placed in the nominal place (Attachment 1). Note that the "legs" were migrated from #4 to #2. There are three poles that defines the location of the OMC Transportation

- The lid was removed and the OMC was inspected (Attachment 2). Immediately found some more delamination of the epoxy beneath the cable bracket (Attachment 3). This needs to be taken care of before shipment.

- The cavity was already flashing as usual, and a bit of alignment made the TEM00 flashing.

- The locking was a little tricky because the LB unit seemed to have a gain-dependent offset. After some adjustment, robust locks were achieved. The cavity was then finely adjusted. Attachment 4 shows the CCD image of the reflection. The core of the spot is more or less axisymmetric as usual. There is also a large helo around the spot. I was not aware of this before. I may need to wipe some of the mirrors of the input path.

- As the satisfactory lock was achieved, I called a day by taking a picture of the table (Attachment 5).

== Initial Preparation ==

• [Done] OMC #002 placement
• [Done] OMC #002 locking
• Details OMC ELOG 414

== Measurements ==

• [Done] Transmission / Power budget before FirstContact OMC ELOG 416
• [Done] Transmission / Power budget after FirstContact OMC ELOG 417
• [Done] Backscatter measurement with a new deflection optics
  • [Done] Optics bonding done waiting for cure OMC ELOG 420 -> Returned the bond to Madeline OMC ELOG 424
  • [Done] Backscatter measurement
    • Measurement: 0.6 ppm OMC ELOG 422
    • (Transmission is 10~60mW. If the backscatter is the order of 1ppm or less, we expect the light level is ~10nW. Can we really detect it? How? ... OK... last time the measurement has been done with the stick PD type powermeter with baffles and the room light turned off (OMC ELOG 209). So it's not totally crazy.)
• [Done] High QE PD preparation / install / QE check
  • [Done] High QE PD inventory check
    • A1-23    LLO OMC#001
    • A1-25    LLO OMC#001
    • B1-01    LHO OMC#003
    • B1-16    LHO OMC#003
    • B1-22    @CIT Cage B1 Cleaned/Installed
    • B1-23    @CIT Cage B2 Cleaned/Installed
    • C1-03    @CIT Cage B3 Cleaned
    • C1-05    Dead / CIT contamination test cav
    • C1-07    Dead / CIT contamination test cav
    • C1-08    @CIT Cage C2
    • C1-09    @CIT Cage C3
    • C1-10    @CIT Cage C4
    • C1-11    @CIT Cage D1
    • C1-12    @CIT Cage D2
    • C1-14    @CIT Cage D3
    • C1-15    Dead / CIT Cage D4
    • C1-17    LHO Spare
    • C1-21    LHO Spare
    • D1-08    not @CIT, maybe LLO Spare?
    • D1-10    not @CIT, maybe LLO Spare?
  • [Done] Install & QE check
    • 1st attempt OMC ELOG 427
    • 2nd attempt OMC ELOG 429
• [Done] Fiber input beam characterization OMC ELOG 421

== Repair / Preparation ==

• [Done] Obtain: UHV Foil (done) / EP30 (found at the 40m OMC ELOG 434) / EP30-2 bonding setup OMC ELOG 442
• [Done] Crimper tool? LLO bought a new one and modify it.
• [Done] BeCu wire clamps:
  • [Done] Sufficient # of clamps found:OMC ELOG 428 / C&Bed
• [Done] FirstContact cavity mirror cleaning (see OMC ELOG 414)
• [Done] FirstContact for protection OMC ELOG 430
   
• Beam dump cleaning -> not necessary
   
• [Done] Replacing the cable bracket
  • [Done] Obtain all parts from Stephen.
  • [Done] Class B Torque wrench present in the lab
  • [Done] Replacement work
    • Recorded the original connections and the cable routing OMC ELOG 431
    • Unmounting the cable bracket OMC ELOG 432
    • Spare situation check OMC ELOG 433
    • Cable bracket replacement OMC ELOG 436
    • New cable tie installed OMC ELOG 437
• [Done] Delamination Repair
  • Delamination status OMC ELOG 414
  • More delamination check OMC ELOG 426
  • Reinforcement parts Inventory OMC ELOG 419
  • Cleaning of the reinforcement bars / Asking Madeline for C&B OMC ELOG 424
  • Delamination of the black glass pieces observed -> reinforcement required OMC ELOG 431
  • Delamination repair part1 OMC ELOG 438  OMC ELOG 439 OMC ELOG 440
  • Delamination repair part2 OMC ELOG 441 OMC ELOG 443 OMC ELOG 444 
• [Done] Check all the fasteners / Ready for the shipment OMC ELOG 445
• Check addon mass configuration OMC ELOG 446  OMC ELOG 447

== Shipping ==

• [Done] Tools to ship to LLO OMC ELOG 448
  • CLASS B special tool kit (Allens / Pliers / Mighty-Mouse spanner / Spatula / etc)
  • FC kit
  • Electronic kit (PD connector / trans-impedance amp)
  • Spare High QE PDs
  • Power meters
  • Glass Beamdumps (for optical testing)
  • Cable bracket replacement kit (PEEK cable bracket / cable pegs / fastners / spare fasteners / kapton sheet / cable ties)
  • Emergency EP30-2 kit (excluding the bond)
     
• [Done] OMC Pelican Filling (Stephen) / OMC Outerbox/insulation (Stephen/Downs) / OMC Shipment Aug 29, 2022 OMC ELOG 445

o Power Budget (2022/07/18)
NPRO ADJ -50 (min)
Fiber incident 62.8mW
Fiber output 45.1mW
Matching to the fiber 72%

DCPD T =  8.90  +/- 0.01  mW
REFPD  =  3.760  +/- 0.001 V

DCPD R =  8.82  +/- 0.01  V
REFPD  =  3.760 +/- 0.001 V

CM1    =  81.4  +/- 0.1   uW
REFPD  =  3.767 +/- 0.001 V

CM2    =  86.6  +/- 0.1   uW
REFPD  =  3.767 +/- 0.001 V

REFLPD
OFS    = -6.214 +/- 0.001 mV (beam blocked)
OFS_REF= +4.587mV

LOCKED =  57.5  +/- 0.5   mV
REFPD  =  3.970 +/- 0.003 V

UNLOCK =  2.816 +/- 0.003 V
REFPD  =  3.943 +/- 0.001 V

P_Inc  =  20.04 +/- 0.01  mW
REFPD  =  3.946 +/- 0.001 V
 

Analysis Result

- Cavity coupling 0.989 (1.1% junk&sidebands)

- Cavity R&T: R=756ppm, T=0.946
- OMC Throughput (Cavity T x First BS R): T=0.939
- Cavity loss per mirror 90 ppm / Round Trip Loss 432ppm

o Power Budget after FirstContact cleaning (2022/07/20)
NPRO ADJ -50 (min)
Fiber incident --.-mW
Fiber output --.-mW
Matching to the fiber ??%

DCPD T =  8.62  +/- 0.01  mW
REFPD  =  3.549  +/- 0.001 V

DCPD R =  9.46  +/- 0.01  V
REFPD  =  3.562 +/- 0.001 V

CM1    =  74.5  +/- 0.1   uW
REFPD  =  3.585 +/- 0.001 V

CM2    =  81.7  +/- 0.1   uW
REFPD  =  3.585 +/- 0.001 V

REFLPD
vOFS    = -6.197 +/- 0.001 mV (beam blocked)
vOFS_REF= +4.58mV

LOCKED =  47.6  +/- 0.2   mV
REFPD  =  3.596 +/- 0.003 V

UNLOCK =  2.700 +/- 0.003 V
REFPD  =  3.590 +/- 0.001 V

P_Inc  =  19.36 +/- 0.001  mW
REFPD  =  3.594 +/- 0.001 V

Analysis Result

- Cavity coupling 0.980 (2.0% junk&sidebands)

- Cavity R&T: R=229ppm, T=0.970 (previous T=0.946, 2.4% UP!)
- OMC Throughput (Cavity T x First BS R): T=0.963
- Cavity loss per mirror 42.8 ppm / Round Trip Loss 238ppm

Bond reinforcement blocks for the invar brackets:

• Attachment 1: CLASS A glass prisms (the surplus of the 2016 repair)
• Attachment 2: Dirty reiforcement bars made of Aluminum
• There are also many dirty prisms in the kit obtained from Stephen

The backscatter beam is supposed to appear in the backpropagation path. The transmission of the OMC has a couple of optics, it's not easy to access that beam.
To try to deflect the beam either horizontally or vertically, small optical pieces were made. (Attachment)

These are the combination of the optics

- Thorlabs PF05-03 Fused Silica Mirror Blank (dia12.7mm x t 6.0mm) + Thorlabs 1/2"sq BB Dielectric Mirror BBSQ05-E03

- Thorlabs PF05-03 Fused Silica Mirror Blank (dia12.7mm x t 6.0mm) + Thorlabs ME05-G01 Protected Al Mirror (dia12.7mm x t 3.2mm) + Thorlabs MRA10-K13 Right-Angle Prism Nd:YAG 10mm

Torr seal was used as the bonding epoxy. It uses a 1:2 volume mixture (not easy because of the viscosity) and is relatively fast to cure (in a couple of hours).
The test piece showed some softness after 3~4 hours so I left the parts cured overnight at room temp (i.e. 18degC)