The OMC #002 is ready for shipment.
Attachment 1: Work done on Sept 19, 2022
Other attachments: Putting the OMC in the pelican case.
Inspected the past LLO add-on mass configuration.
There are unknown masses at the DCPD side. It looks like a small SS mass with an estimated mass of 5g. But the DCC number is unknown.
We are going to add 10g on each corner as well as the damping aterial. We should be able to figure out the fastener / mass configuration.
Here is the balance mass info for the LLO OMC#001 analyzed from the photographs
If we attach the additional mass, longer 1/4-20 screws (1", 1" 1/8, 1" 1/4) are going to be used.
Started July 15, 2022 and finished Aug 30. So it took ~1.5 months (with a couple weeks of break)
Class B special tools
First Contact Kit
Bonding kit (excl EP30-2 bond)
Power meters (excl Power meter controller)
Cable bracket replacement kit
Optics / Optomechanics
=== Action done on Aug 30 ===
Fiber MM setup / Fiber coupler mount
Glass Beamdumps (for optical testing)
Thorlabs fiber coupler tool
General bent nose plier for fiber
Thorlabs collimator tiny allen
Spare High QE PDs
Spare OMC bags / Zip bags
Balance Mass 10g Qty 8 (Different Type D11*** 1.25" dia), 20g Qty 10 / Mass damper D1700301 -04 / Mass damper screws SHCS 1/4-20 x 1.25 Qty 25 / 1" screws and 1 1/8" screws
Shipping request: https://services1.ligo-la.caltech.edu/FRS/show_bug.cgi?id=25002
=== Low supply! ===
Upon the LLO work, the current PD arrangement in the cages are:
B1 OMC1 PDT (A1-23)
B2 OMC1 PDR (A1-25)
B3 original (C1-03)
B4 OMC2 PDT (B1-22)
C1 OMC2 PDR (B1-23)
C2 original (C1-08)
C3 original (C1-09)
C4 original (C1-10)
Clean Supply Ordered
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.
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.
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.
- 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
We started buikding the OMC #4.
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.
- 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.
- 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.
- 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).
CM1: PZT ASSY #8 (M7+PZT11+C11)
CM2: PZT ASSY #11 (M14+PZT13+C13)
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.
- 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
- 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.
CM1: PZT ASSY #8 (M7+PZT11+C11)
CM2: PZT ASSY #11 (M14+PZT13+C13)
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.
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.
- We don't need to remove the invar block.
- Action Item: Reinforcement of the bonding
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.
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
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.