Upon the LLO work, the current PD arrangement in the cages are:
CAGE B
B1 OMC1 PDT (A1-23)
B2 OMC1 PDR (A1-25)
B3 original (C1-03)
B4 OMC2 PDT (B1-22)

CAGE C
C1 OMC2 PDR (B1-23)
C2 original (C1-08)
C3 original (C1-09)
C4 original (C1-10)

OMC #001

• ICS Link: https://ics.ligo-la.caltech.edu/JIRA/browse/ASSY-D1201439-1
• Already marked as disassembled
• Removed two PDs
  • https://ics.ligo-la.caltech.edu/JIRA/browse/IHGQEX3000-0-00-A1-25
  • https://ics.ligo-la.caltech.edu/JIRA/browse/IHGQEX3000-0-00-A1-23
• Shipped to CIT
  • https://ics.ligo-la.caltech.edu/JIRA/browse/Shipment-12455

OMC #002

• ICS Link: https://ics.ligo-la.caltech.edu/JIRA/browse/ASSY-D1201439-002
• Disassemble to remove "assembled" mark
• Removed two Excelitas PDs
• Added IHGQEX3000-0-00-A1-23 and IHGQEX3000-0-00-A1-25
• Removed the cable connector bracket
• Added the new PEEK connector bracket 
  (This part was just "shipped" from CIT to LLO in ICS: https://ics.ligo-la.caltech.edu/JIRA/browse/Shipment-12458)
  https://ics.ligo-la.caltech.edu/JIRA/browse/D1300052-V3-00-0001
• Marked "Assembled"
• Stored: https://ics.ligo-la.caltech.edu/JIRA/browse/Storage-12456

Clean Supply Ordered

• TexWipe TX8410 AlphaSat Vectra Alpha 10 50 sheets x 12 pk  (VWR TWTX8410)
• Mask KIMTECH PURE® M3 Pleat-Style Face Masks 50 masks x 10 pk (VWR 15628-213)
• Stainless Pan x3 (VWR 10193-562)
• Ansell Accutech Latex Gloves 6.5 25*8pk (Fisher 19162026)
• Ansell Accutech Latex Gloves 7.0 25*8pk (Fisher 19162027)

Monday, November 14, 2022

Camille and Koji did a "deep cleaning" of OMC#1:
1) Applied First Contact to the mirror surfaces. Removed first contact after ~10 minutes.
2) Acetone scrub of the mirror surfaces with a cotton swab.
3) Applied First Contact again. Removed after ~10 minutes. We left the FC paint on for the work on Thu.

The foggy spot on the input mirror was unchanged after the first round of First Contact. But the foggy spot came off during the acetone scrub.

[Camille, Koji]

The damaged black glass was removed from the OMC breadboard leaving the glass base.
The black glass pieces were bonded very tightly on the FS base with EP30-2. The apparent amount of the bond was not so much but it was such hard that removal by hand was not possible.
We decided to give drips of Acetone on the base hoping the gradual dissolving of EP30-2. Using a knife edge, the "filets" of the bonds were removed, but the BD was still tight.

By wedging the black glass-black glass bonding with the nife edge, the left side (the directly damaged one) was taken off from the structure leaving a tiny fragment of the glass on the base.

The remaining one was even stronger. We patiently kept dripping Acetone on the base and finally, the black glass piece was knocked off and removed from the base.

Attachment 1: The base right after the black glass removal.

Attachment 2: The black glass pieces were stored in a container with Al foil + clean cloth bed. The damaged and fogged surfaces faced up.

Attachment 3: The zoom-in shot of the black glass pieces.

Attachment 4: The base was wiped with Acetone and cleaned with FC. We will bond another BD assembly on the base, presumably using the UV epoxy.

[Camille, Koji]

Photo of the BS1 AR cleaning process

Attachment 1: Before cleaning. Foggy surface is visible.

Attachment 2: After FC cleaning. The structure of the deposited material is still quite visible.

Attachment 3: Acetone scrubbing. Cotton Q-tip was used so that the stick does not melt with acetone.

Attachment 4: After acetone scrubbing. Nicely clean!

Acetone scrubbing was applied to HR/AR of BS1, FM1, FM2, BS2, and HR of CM1 and CM2. (total 10 surfaces)
Then final FC paint was applied to these 10 surfaces.

We'll come back to the setup on Thu for FC peeling and loss measurement.

[Camille, Koji]

- Removed the first contact we left on Monday.

- Measured transmission (Set1) Very high loss! Total optical loss of 18.5%! Observation with the IR viewer indicated that CM1 has bright scattering. We suspencted a remnant of FC.

- Applied the second FC on the four cavity mirrors. This made the CM1 sport darker.

- Measured the transmission (Set1~Set3). We had consistent loss of 4.2~5.0%. We concluded that this is the limitation of this OMC even with the cleaning.

The four cavity mirrors in OMC #1 were each scrubbed using acetone and a cotton swab.
Then, the four mirrors were painted with First Contact (picture attached). The First Contact was allowed to dry for 20 minutes, then removed while using the top gun.

OMC Transmission measurement after the 2nd deep cleaning

The 2nd deep cleaning didn't improve the transmission. (See Attachment 2)
The measured loss was 0.044+/-0.002

[Camille Koji]

We started buikding the OMC #4.

• Removed OMC #1 from the optical setup and placed it at a safe side on the optical table/
• Fixed OMC #4 in the optical setup
• Cleaned the OMC cavity mirrors
• Placed the OMC cavity mirrors
  • FM1: A1
  • FM2: A3
  • CM1: PZT #11
  • CM2: PZT #12
• Aligned the beam to the cavity
• Locked the cavity on TEM00
• Finely aligned the beam to the cavity

[Koji, Camille]

We worked on the bonding of the flat mirrors for the OMC cavity with UV epoxy.

- Prepared the UV illumination setup. Cleaned up the table a bit to spare some space for the illuminator.
- Checked the output power of the illuminator. The foot pedal worked fine. The timer was set to be 10s. The UV output from the fiber was nominally 6W. This is after some warming up for ~1min. (Checked the output power continuously with the UV power meter.)

- Checked the cavity alignment / FSR / TMS - it looked good at this moment

- We confirmed that the UV epoxy has an expiration of July 3, 2023. The bond capsule was brought from Downs right before the work started, and thawed at the lab.

FM1 bonding

- The bottom of FM1 and the breadboard were cleaned. Cleaning with lens cleaning paper + IPA remained a few specks of dust on the surface. We decided to use Vectra swabs to wipe the breadboard surface. This worked pretty well.
- Applied a tap of UV epoxy to FM1 and placed it on the template. The optic was constrained by a retainer clip.
- We found that the spot positions were significantly moved. Probably FM1 was not well touching the template before. We tried to recover the previous optical axis by aligning CM1 and CM2.
- Here is the tip: align the beam on CM1 at the desired spot. Move CM1 to bring the spot on CM2 to the desired spot. CM2 is aligned to have TEM00 as much as possible.

- We recovered reasonable spots on the mirrors. Measured the FSR and TMS (vertical and horizontal) to be 264.73MHz, 58.18MHz, and 58.37MHz, respectively. This makes the 9th-order modes well separated from TEM00. Very good.

- Gave UV illumination 10s x 2. Confirmed that the mirror is rigidly bonded.

FM2 bonding

- Continued to bond the other flat mirror. The same process was repeated.
- The bottom of FM2 and the breadboard were cleaned.
- Applied a tap of UV epoxy to FM2 and placed it on the template. The optic was constrained by a retainer clip.
- Measured the FSR and TMS (vertical and horizontal) to be 264.7925MHz, 58.15MHz, and 58.3725MHz, respectively. This makes the 9th-order modes well separated from TEM00. Very good.

- Gave UV illumination 10s x 2. Confirmed that the mirror is rigidly bonded.

SM1/BS2/BS3 bonding

- Continued to bond some less important mirrors.
- SM1 was placed on the template with the same step as above. BS2 (for QPD) and a dummy QPD housing were also placed just to check if the optical axis has any inconsistency. The good beam alignment on the QPD housing was confirmed.
- Applied a bond to SM1 and blasted the UV (20s)
- Applied a bond to BS2. Checked the alignment on QPD1 again. It looked good. UV illumination was applied.

- Placed BS3 to the cavity transmission. A dummy DCPD housing was placed at the reflection side of BS3. There was no inconsistency with the beam alignment.
- The UV illumination was applied (20s).

Optic Inventory

Breadboard: #6
BS1: E6
FM1: A1
FM2: A3
CM1: PZT ASSY #8 (M7+PZT11+C11)
CM2: PZT ASSY #11 (M14+PZT13+C13)
SM1: E9
BS2: B8
SM2:
SM3:
BS3: B6

[Camille, Koji]

We continued to bond two CM mirrors and the other two steering mirrors for QPD2.

Before the bonding work, the FSR and TMSs were checked again.

FSR: 264.7925 MHz
TMS_V: 58.15125 MHz
TMS_H: 58.33375 MHz

Checked the transmission: The OMC loss was 4.3 +/- 0.2 %.

This does not make the HOMs coincidently resonant until the 18th-order (+9MHz). Looks good.

CM1/CM2/SM2/SM3 bonding

- Applied the bond to CM1 and the UV illuminated.
- Applied the bond to CM2 and the UV illuminated.
==> The cavity bonding is completed.

Removed the micrometer for CM2 to allow us to bond SM2/SM3
- Checked the spot at QPD2: The spot was a couple of mm too left. This was too much off compared to the QPD adjustment range. ==> Decided to shim the SM3 position with a piece of Al foil.
- Otherwise everything looked good. SM2/SM3 were bonded.

Invar block bonding

Prepared EP30-2
- There are three tubes of EP30-2 that expires on 2/22, 2023.
- A tube was almost empty. Used this tube to fill/purge the applicator. The 2nd tube was then attached to squeeze out 8g of glue mixture. 
- 0.4g of fused silica beads were added to the glue mixture.
- Mixed the bond and a test piece was baked by the oven. (200F=95C, 5min preheat, bakeing 15min).
- The glue test piece was "dry" and crisp. Looked good.
- Applied the glue on the invar blocks. Confirmed that the bonding surfaces were made completely "wet".
- 4-40 screws were inserted to the blocks so that the blocks were pushed toward the template. See Attachments 3 and 4.

Optic Inventory

Breadboard: #6
BS1: E6
FM1: A1
FM2: A3
CM1: PZT ASSY #8 (M7+PZT11+C11)
CM2: PZT ASSY #11 (M14+PZT13+C13)
SM1: E9
BS2: B8
SM2: E11
SM3: E14
BS3: B6

Qty1 1/2 mounts
Qty2 prism mounts
Qty6 gluing fixures
Qty1 Rotary stage
Qty1 2" AL mirror
Qty1 Base for the AL mirror

=> Handed to Stephen -> Camille on Jan 27, 2023.

[Camille, Koji]

The bottom side template was separated into two pieces and successfully removed from the breadboard. The template was assembled together again and bagged to store it in a cabinet.

We found that the invar block for DCPD(R) was bonded with some air gap (Attachment2 1/2).

The Allen key used as a weight was too small, which caused it to get under one of the screws used as hooks and lift the block.

We've investigated the impact of this tilt.

- Bonding strength: The bonding area is ~60% of the nominal. So this is weak, but we can reinforce the bonding with an aluminum bar.
- Misalignment of the DCPD housing: The tilt will laterally move the position of the DCPD. However, the displacement is small and it can be absorbed by the adjustment range of the DCPD housing.
- Removal: From the experience with the removal of the beam dump glass, this requires a long time of acetone soaking.

Conclusion:

- We don't need to remove the invar block.
- Action Item: Reinforcement of the bonding

[Camille, Koji]

During the second UV epoxy session, we did not bond the input beam dump. This is because this beam dump was not the one planned from the beginning and if it was bonded in place, it would have created difficulties when removing the template.

First, we aligned a couple of Allen wrenches to define the location of the beam dump. We've checked that the main transmission is not blocked at all while the stray beam from the OMC reflection is properly dumped.

After the confirmation, the UV epoxy + UV alight were applied.

The resulting position of the beam dump is shown in the attachment.

A beam dump was stacked on the base of the previous beam dump. The angle was determined so that the main transmission goes through while the stray OMC reflection is blocked without clipping at the edge.

The resulting alignment of the beam dump is shown in Attachment 1.

The beam dump tended to slip on the base. To prevent that a couple of weights were placed around the bonding area. (Attachment 2)

The AL metal bracket was replaced with a PEEK version.

Attachments 1/2: Before the replacement. The photos show how the cables are arranged.

Attachment 3: How the replacement work is going. The 1/4-20 screws were super tight. Once the connectors were removed, an Allen key was inserted to a hole so that the 1/4-20 on the short sides were removed by closing Allen key arms. For the screws on the longer sides, the same technique can be applied by using three Allen keys. This time none of the screws/cable pegs were wasted. The clothes were used to protect the breadboard from any impact of the action.

Attachments 4/5: Final state.

OMC #1 repair has been 100% done

---------

We still have 4 correct cable pegs and many 1/4-20 BHSCs for OMC #4.

Yesterday, we noticed that we could not close the transport fixture for OMC #4. We could not fully rotate the knobs of the locks. Today, I took the hooks from the functioning locks of the spare transport fixture.

It turned out that the default dimension of the lock seemed too tight. The functioning one has the through holes elongated by a file or something. This modification will be necessary for future transport fixtures.

The transport fixture was brought to the 40m clean room to use as an assembly reference.

Inserted 4-40 and 2-56 helicoils into the DCPD/QPD housings for the 4th OMC. The retainer caps were also fastened to the housings.

2/1 2:30PM~ Bonding reinforcement (Last EP30-2 gluing)

2/2 1:00PM~ Peripheral attachment / Optical testing setup

[Camille, Thejas, Koji]

We added a reinforcement bar at the back of the invar block which had the tilt issue.

The reinforcement bar was added to the backside rather than the side or front such that the DCPD housing does not interfere with the reinforcement bar.

Also, small amount of EP30-2 was added to the CM2 wire so that the repeated bend of the PZT wire cause the disconnection at the PZT.

The attached photo shows the resulting bond spread.

HEPA is quite low for a tall person and also the curtain on the back of us is always heavy. It's very tough for anyone to work with. (See Attachment 1)

I did the lab and table organization so that the HEPA expansion work can be resumed.
The 4th OMC is still on the table with the transport fixture (See attachment 3), but it is secured on the table. The risk of damaging the OMC is low now.

Chub can start working on the HEPA. Occasionally Camille and Thejas may work on the optical setup with the OMC. It is fine as long as both happen at the same time.

The OMC cables #4 arrived on Feb 3rd. (See Attachment)

This shipment included two DCPD cables and two QPD cables. It means that the direct wiring from the PZT to the mighty mouse connectors was not included in the shipment.

Attachment 1: North Cabinet 2nd from the left

Attachment 2: North Cabinet 3rd from the left

Attachment 3: South Cabinet (right)

Inspection

Updated ICS (Shipment-12578) and moved those parts to Storage-9482.

Inspection showed the following:

• Serial numbers matched the packing list
• SN S1301807: We observed some discoloration on the Gore wire close to one cable termination. [Attachment 1]
  • greenish tint
  • appeared to be superficial
  • slight removal observed when gently wiped with an IPA soaked AlphaWipe ("red wipe")
  • did not follow the helical of the teflon sheath
  • recommend additional inspection when Unit 4 build is resumed
• Cables were returned to the box labeled "OMC Cables" in the south cabinets in the OMC lab.

Observations for aLIGO OMC Unit 4 Build

An ICS Record Navigator search of onboard OMC cables reveals the following quantities appear to have been fabricated for aLIGO.

• D1300371 = Qty 3
• D1300372 = Qty 5
• D1300374 = Qty 3
• D1300375 = Qty 5

The leftover cables are all of the long variety (D1300372, D1300375), and the received quantities make sense. 3 aLIGO OMC assemblies used quantity 3 of each cable, leaving the remaining cables which had been stored at LHO:

• D1300372 = Qty 2
• D1300375 = Qty 2

The received cables from LHO may apparently be used interchangably, and the extra slack (~ 5", compared to the D1300371, D1300374 part numbers) should be managable.

Next Steps for aLIGO OMC Unit 4 Build

We will move forward in fabricating Unit 4 with the received cables from LHO, despite their extra length.

To complete the Unit 4 on board cable set (refer to OMC_Lab/203), we will need to crimp pins onto the PZT leads, and we need to find, clean, and bake quantity 1 4 pin mighty mouse connector.

• PZT leads terminate crimp pins inserted into Glenair Mighty Mouse 803-003-07M6-4PN-598A (per OMC_LAB/203, record navigator)
• Cable bracket interface to OMCS is Glenair Mighty Mouse 803-003-07M6-4PN-598A (per D1300376-v3).

I will ask Chub to see if there are any Class A spares of the PZT termination connector already on hand.

Chub, JC, and co worked on the HEPA enclosure improvement.

On Feb 16, Camille and I attampted at locking the OMC cavity. It was quick to re-align the beam to the cavity (by using only the fine adjustment of the output fibre couple). This was done by looking to minimize the power reflected from the cavity and observing the mode shapes on the CCD. After we achieved locking we placed the lid of the OMC back and turned off the laser. 

Chub finished the HEPA enclosure extension project.

This is a test bake conducted in Air Bake Oven A (ABO-A) held in the 40m Clean and Bake facility. The overall objective is to sucessfully cure the Curved Mirror Subassemblies with the appropriate temperature profile. In this test run, we wanted to ensure that the temperature profile dictated via the Platinum software is stable and repeatable.

Specific curing instructions can be found in LIGO-E1300201-v1, section 6.2.4 (https://dcc.ligo.org/E1300201-v1). This test air bake load contained several stainless steel masses and a stainless steel tray that will be utilized in the production curing run. Note that the thermacouple has been placed between two stainless steel masses.

Temperature profile results from 4/14/23 test cure can be seen in attachments below.

[Camille, Koji, Thejas]

Yesterday, we cleaned the cavity optics with first contact, aligned the input laser beam to the cavity and measured the power at different terminals on the cavity breadboard. 

The measured OMC losses were:
SET1 0.042 +/- 0.003
SET2 0.035 +/- 0.002
SET3 0.030 +/- 0.0014
-> 0.033 +/- 0.001

The measured OMC mode-matching efficiencies were:
SET1 0.9795 +/- 0.00016
SET2 0.9797 +/- 0.00005
SET3 0.9794 +/- 0.00035

Attached herewith is the scrrenshot of the notes of with input power parameters.

A+ OMC Build efforts ongoing or completed this week:

•  PZT lead onboard strain relief (D2000172)
  • Brief discussion in A+ SUS call - PEEK material callout is to be updated in v2, Don is handling this.
  • v1 drawings posted and UK team out for production, with Angus already communicating PEEK grade requirement to vendor during procurement process.
  • DCN is WIP per Russell.
• Rework of Helicoil holes
  • D1201278 and D1300498 were already Class A, but we recognized that the hole callouts were not consistent with current LIGO notation, and we decided to make sure that these holes were in a good state.
  • Don and I chased the holes with taps (gloves on, but in a dirty area)
  • Don created a C&B Ticket request/1835
• PZT characterization (ref. T1500060-v2 - PZT Testing Section 2.3.2)
  • DC Response measurement - see OMC_Lab/542 for initial findings.
    • 11 units appear to be good, 2 units appear to be damaged, 5 units need to be recharacterized (after soldering rework).
    • Quantitative results WIP.
  • Lab move to Downs 320 - this work needs to be logged.
    • DC Response setup updated, beam focusing was changed.
    • Oplev setup for Length to Angle measurement constructed for the first time.
• Component matching for Curved Mirror Subassembly
  • Continued work on algorithm-based matching code
  • Discussion with Gari and Calum - we will move toward manual matching to expedite

We have the following plans for the week ahead:

• Complete PZT DC Response data analysis.
• Finish solder rework of PZT leads.
• Start PZT Length to Angle measurement.
• Manually match Curved Mirror Subassembly components, enough to bond first 4 assemblies.
  • (this will be pending full characterization of PZTs)
• Make sure clean and bake ticket gets processed for reworked parts mentioned above.

We have the following near future plans:

• Start PZT reliability testing (burn-in test) (ref. T1500060-v2 - PZT Testing Section 2.3.4),
  • Focused on units that will be used to bond first 4
• Bond first batch of Curved Mirror Subassemblies.
  • Make sure we have enough EP30-2 for subsequent batches (some used by HoQi effort)..
• Resume transport fixture build effort at 40m Bake Lab.
• Conduct walkthrough of OMC lab with build in mind.
• Follow updates of top level assy D2000172, and send finalized assy for 3D printing of mockup unit.

Loan Record: I borrowed a PD can opener from Rich => Antonio Returned Sep 9, 2016

Tungsten Carbide Engraver (permanently given to the OMC lab)

KEITHLEY SOURCE METER + Laptop

Antonio borrowed: Rich's PD cutter (returned), Ohir power meter(returned), Thorlabs power meter head, Chopper

Xiaoyue

QPD head
X-Z stage
Mounting brackets
DB15 cable
QPD matrix circuit
+/-18V power supply cable

I’ve borrowed the black and decker toaster oven to dry some sonicated parts. It is temporarly located in the QIL lab. 

From Cryo Cav setup

Borrowed LB1005 Servo box -> OMC

Black and Decker Glue Baking Oven came back to the OMC lab on Aug 10, 2020, Georgia had lent the unit for the SAMS assembly/testing.

I handed Camille the C7 mirror for the cross-calibration of the ROC characterization techniques.

Borrowed for PZT DC Response Shadow Sensor Setup (see Attachment 1):

• Thorlabs PDA100A Photodiode (and power supply)
• Thorlabs MDT694B Piezo Driver

Current Location: Downs 227

The ThorLabs MDT694B piezo driver was returned to the OMC lab.