Mon Sep 28 16:13:08 2020, Koji, General, General, OMC Beam Dump Production Cure Bake
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.
Thu Oct 8 19:55:22 2020, Koji, General, Characterization, Power Measurement of Mephisto 800NE 1166A
The output of Mephisto 800NE (former TNI laser) was measured.
The output power was measured with Thorlabs sensors (S401C and S144C). The reference output record on the chassis says the output was 837mW at 2.1A injection.
They all showed some discrepancy. Thus we say that the max output of this laser is 1.03W at 2.1A injection based on the largest number I saw.
Fri Oct 9 01:01:01 2020, Koji, General, General, TFT Monitor mounting
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.
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.
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.
Fri Oct 16 00:53:29 2020, Koji, General, General, TFT Monitor mounting
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.
Fri Oct 23 19:09:54 2020, Koji, General, General, Particle counter transfered to Radhika
See this entry: https://nodus.ligo.caltech.edu:8081/40m/15642
Fri Nov 6 18:38:00 2020, Koji, General, General, Powermeter lent from OMC Lab to 2um ECDL
Thorlabs' powermeter controler + S401C head was lent from OMC Lab. Returned to OMC Jul 15, 2022 KA
Mon Nov 9 22:06:18 2020, Koji, Mechanics, General, 5th OMC Transport Fixture
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.
Fri Nov 20 18:51:23 2020, Koji, General, General, Instrument loan
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.
Sat Nov 21 13:58:30 2020, Koji, Electronics, Characterization, Dark Current Measurement for InGaAs QPDs
Dark current measurement for InGaAs QPDs (OSI FCI-InGaAs-Q3000) has been done using Keithley 2450 and Frank's diode test kit. Frank's setup uses various custom instruments which are no longer exist, therefore the kit was used only for switching between the segments.
The diodes were serialized as 81, 82, 83, 84, continuing the numbering for the OMC QPDs. The numbers are engraved at the side and the back of the diode cans.
Overall, the QPDs nominally indicated the usual dark current level of <10nA.
SEG1 of #82 showed a lower voltage of reverse breakdown but this is not a critical level.
#83 showed variations between the segments compared to the uniform characteristics of #81 and #84.
Sun Nov 22 13:49:12 2020, Koji, Electronics, Characterization, Impedance Measurement for InGaAs QPDs
To know any anomaly to the junction capacitance of the QPD segments, the RF impedances were tested with a hand-made impedance measurement.
All segments look almost identical in terms of capacitance.
The impedance of a device can be measured, for example, from the complex reflection coefficient (S11). To measure the reflection, a bidirectional coupler was brought from the 40m. Attachments 1 and 2 shows the connection. The quantity A/R shows S11. The network analyzer can convert a raw transfer function to an impedance in Ohm.
Calibration and Measurement limit:
The network analyzer was calibrated with 1) a piece of wire to short the clips 2) 50ohm resistor 3) open clips. Then the setup was tested with these three conditions (again). Attachment 3 shows the result. Because of the impedance variation of the system (mainly from the Pomona clip, I guess), there looks the systematic measurement error of ~1pF or ~25nH. Above 100MHz, the effect of the stray impedance is large such that the measurement is not reliable.
The setup was tested with a 10pF ceramic capacitor and this indicated it is accurate at this level. The setup is sufficient for measuring the diode junction capacitance of 300~500pF.
Impedance of the QPD segments:
Then the impedances of the QPD segments were measured (Attachment 4). The segments showed the identical capacitance of 300~400pF level, except for the variation of the stray inductance at high freq, which we can ignore. Note that there is no bias voltage applied and the nominal capacitance in the datasheet is 225pF at 5V reverse bias. So I can conclude that the QPDs are quite nominal in terms of the junction capacitance.
(Ed: 11/23/2020 The RF components were returned to the 40m)
Mon Nov 23 23:17:19 2020, Koji, Electronics, Characterization, The dark noise of the Q3000 QPDs
The dark noise levels of the four Q3000 QPDs were measured with FEMTO DLPCA200 low noise transimpedance amp.
The measurement has been done in the audio frequency band. The amp gain was 10^7 V/A. The reverse bias was set to be 5V and the DC output of the amplifier was ~40mV which corresponds to the dark current of 4nA. It is consistent with the dark current measurement.
The measured floor level of the dark current was below the shot noise level for the DC current of 0.1mA (i.e. 6pA/rtHz).
No anomalous behavior was found with the QPDs.
Note that there is a difference in the level of the power line noise between the QPDs. The large part of the line noises was due to the noise coupling from a soldering iron right next to the measurement setup, although the switch of the iron was off. I've noticed this noise during the measurement sets for QPD #83. Then the iron was disconnected from the AC tap.
Tue Nov 24 12:27:18 2020, Koji, Electronics, Characterization, The dark noise of the Q3000 QPDs
The amplifier BW was 400kHz at the gain of 1e7 V/A. And the max BW is 500kHz even at a lower gain. I have to setup something special to see the RF band dark noise.
With this situation, I stated "the RF dark noise should be characterized by the actual WFS head circuit." in the 40m ELOG.
Thu May 20 17:03:50 2021, Koji, General, General, SRS LCR meter SRS720 borrowed from Downs
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
Sun May 30 15:17:16 2021, Koji, General, General, DCPD AF capacitance measirement
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
Sun May 30 15:32:56 2021, Koji, General, General, DCPD AF capacitance measirement
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.
Thu Jun 23 21:03:33 2022, Koji, Facility, General, Moving the small optical table to CAML (TCS Lab)
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.
Tue Jun 28 16:13:34 2022, Koji, General, General, The small optical table not small enough to get out
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
Fri Jul 15 22:14:14 2022, Koji, General, General, OMC Lab recovery for the OMC #002 test
- 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).
Mon Jul 18 14:20:09 2022, Koji, General, General, OMC #002 Plan Portal
== 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
- [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] 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
- [Done] Delamination Repair
- [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
Tue Jul 19 03:17:56 2022, Koji, General, General, OMC #002 Power Budget before mirror cleaning
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
OFS = -6.214 +/- 0.001 mV (beam blocked)
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
- 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
Thu Jul 21 02:55:06 2022, Koji, General, General, OMC #002 Power Budget after mirror cleaning
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
vOFS = -6.197 +/- 0.001 mV (beam blocked)
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
- 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
Thu Jul 21 13:21:27 2022, Koji, General, Configuration, Windows laptop for WincamD Beam'R2 recovery
The Windows laptop for WincamD/Beam'R2 (DELL Vostro3300) was not functional.
- Windows 7 got stuck in the starting up process (Google "startup repair loop")
- The battery can't charge and the adapter connection is flaky
I decided to newly install Win10.
I made a new bootable Win10 DVD from the ISO downloaded from IMSS. The ISO file was converted to CDR using Disk Utility on Mac.
This deleted the past disk partitions. The installation process has no trouble and Win10 ran successfully. The machine is slow but still acceptable for our purpose.
Dataray Version 7.1H25Bk was downloaded from the vendor website https://dataray.com/blogs/software/downloads and installed successfully.
The devices ran as expected by connecting the heads and selecting the proper device in the software.
Then, the Win10 fell into "Hibernation Loop" and "Shutdown loop" (after disabling hibernation in the safe mode).
This is probably the combination of extremely slow windows update (feature update i.e. beta OS update) and the occasional shutdown due to the flakiness of the AC connection
Win10 was reinstalled and automatic Win update was disabled via windows policy manager or something like that. Still, it tries to download and update some of the updates (what's happening there!?
Here are my strong recommendations on how to use this laptop
- Do not use any network connection. It will enable Windows Update kicks in and destroy the machine.
- Use a USB stick for data transportation if necessary
- Buy a replacement battery (maybe a 3rd-party cheap one
- The Win10 DVD should always be inserted into the laptop's drive so that we can reinstall the windows anytime.
Thu Jul 21 14:35:35 2022, Koji, General, General, Bond reinforcement blocks for the invar brackets
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
Thu Jul 21 14:55:48 2022, Koji, General, General, Optics bonding for the backscatter measurement
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)
Thu Jul 21 17:47:00 2022, Koji, General, General, The profile of the beam incident on the fiber input coupler
The profile of the beam incident on the fiber input
The fiber input was deflected by a 45deg mirror. The beam profile was measured with WincamD. The beam was too strong (~60mW) even at the smallest pump power (ADJ -50) of the NPRO. So the two ND20 filters were added to the lens right before the 45 deg mirror and the camera.
The measured profile had some deviation from the nice TEM00 particularly around the waist. This could be a problem of the too small beam on the ND filter and the CCD.
This is not an issue as we just want to know the approximate shape of the beam.
For the fiber coupling, if we have the beam waist radius of ~200um it is sufficient for decent coupling.
Fri Jul 22 00:31:17 2022, Koji, General, General, OMC #002 backscatter measurement
Measure the power ratio between the forward-propagating and reverse-propagating beams.
- Place a small deflecting mirror at the transmission.
- Place a flat mirror at the deflected transmission. When the alignment of this mirror is adjusted to retroreflect this beam, the DC of the cavity reflection PD increases, and also the CCD shows spurious fringes.
- This condition allows us to locate the power meter at the reverse-propagating spot of the transmission (Attachment 1)
- Place a black glass beam dump for the main (bright) transmission (Attachment 2)
- Now the power meter is receiving the counter-propagating beam. Turn off the room light and place an anodized Al baffle as shown in Attachment 2. Move the baffle to block only the counter-propagating. Move the baffle out. => Record the power meter reading with/without the baffle in the counter-propagating path. The difference is the power of the reverse-propagating beam.
- Now measure the power of the reflected main transmission. This tells us the power ratio between the foward- and back-propagating beams.
- Remove the small deflecting mirror and measure the power of the main transmission.
- Now the back-propagating power can be estimated from 6 and 7. The same amount is going back to the IFO path.
- The reflectivity can be calculated from the 7 and the transmission
- To increase the incident laser power, NPRO Current ADJ was set to be 0 (increased from -50)
- 1st: Without the baffle 0.373 +/- 0.001 uW / With the baffle 0.318 +/- 0.001 uW
- 2nd: Without the baffle 0.370 +/- 0.001 uW / With the baffle 0.318 +/- 0.001 uW
- 3rd: Without the baffle 0.370 +/- 0.001 uW / With the baffle 0.317 +/- 0.001 uW
==> 53.3 +/- 0.6 nW
- The main transmission was 84.0mW
==> Backpropagation ratio was 0.634+/-0.007 ppm
- Direct measurement of the OMC was after BS 96.6mW
==> Backpropagation power from the cavity: 61.3 +/- 0.7 nW
- Cavity transmission for the matched beam is Tcav RinputBS = 0.963
==> Incident resonant TEM00 power 100.3mW
- Reflection 61.3+/-0.7 nW x RinputBS = 60.8+/-0.7 nW
-> The effective reflectivity for the mode-matched resonant TEM00 beam incident on the OMC (1st steering mirror) is 0.606+/-0.007 ppm
Fri Jul 22 17:41:01 2022, Koji, General, General, SRS LCR meter SRS720 returned to Downs
SRS LCR meter SRS720 was returned to Downs as before.
Fri Jul 22 17:47:38 2022, Koji, General, General, C&B request for the reinforcement blocks
OMC Reinforcement blocks
1. P/N D1600316; Version v4; Type 01; Qty 30; Source Chemistry Machine Shop
2. P/N D1600316; Version v4; Type 02; Qty 15; Source Chemistry Machine Shop
3. P/N D1600316; Version v4; Type 01; Qty 40; Source Resource MFG PO S422806
4. P/N D1600316; Version v4; Type 02; Qty 40; Source Resource MFG PO S422806
Stephen asked Srinath for the ICS entry.
Stephen made the C&B request https://cleanandbake.ligo.caltech.edu/clean_and_bake/request/1708/
Madeline was asked to take care of the C&B.
Also, the Torr Seal box was returned to Madeline.
Mon Jul 25 18:25:04 2022, Koji, General, General, A/C Filter was replaced
New filter PN
TK70457312T Mini-Pleat Air Filter, Style - Air Filters Box, Performance Rating MERV 14, Nominal Filter Size 12x24x2
Previous filter PN
Global Industrial Equipment
Extended Surface Pleated Cartridge Filter Serva-Cell Mp4 Slmp295 12X24X2 Gl WBB431699
-> No longer available
Tue Jul 26 00:01:59 2022, Koji, General, General, OMC #002 delamination check 2
More epoxy delamination check:
DCPD R (Attachment 1): Found half delaminated
DCPD T (Attachment 2): Found half delaminated
QPD1/QPD2 (Attachment 3): Looks fine
In total we need to fix bonding of three invar bases (including the one for the cable bracket)
Tue Jul 26 00:12:58 2022, Koji, General, General, High QE PD: QE measurements
- Installed the High QE PDs to OMC #002
- B1-22@Cage B1 was installed to the transmission DCPD
- B1-23@Cage B1 was installed to the reflection DCPD
Upon the installation, the legs of the PDs were cut by 3mm. Also, the tab of the PD could not be embedded in the DCPD housing. Therefore, the tabs were cut.
The alignment looked just fine. The weak reflections are directed to the black glass beam dumps.
- After the installation, the QEs were measured.
- With Thorlabs S130C power meter, the QE was estimated to be ~95%. (Accuracy +/-7%)
- With Thorlabs S401C power meter, the QE was estimated to be ~100%. (Accuracy +/-3%)
It is so confusing. So I decided to make the QE test setup.
Ophir RM9 with chopper (+/-5%): 8.97mW
Thorlabs S140C integrating sphere (+/-7%): 9.11mW
Thorlabs S130C PD power meter (+/-7%): 9.15mW
Thorlabs S401C thermal power meter (+/-3%): 8.90mW
So there looks ~3% discrepancy between S130C and S401C
Then tried to measure the QE of C1-03@Cage B3 with Ophir RM9
- Initial state: QE=0.95
- First FirstContact application: QE went up to 0.973
- Second FirstContact application: QE = 0.974, basically no change
- Calibrate the trans-impedance amp with Keithley
- Apply FC to B1-22 and B1-23 to see if there is an improvement
- The power should be measured with S401C because the accuracy seems better (+/-3%).
- Take photos of the PD FC process
General To Do:
- Backscatter test 2nd trial
- Start applying the first contact to the optical surfaces
- Beam dump cleaning
- Apply FC cap to the PDs
- Delamination repair (light side)
- Delamination repair (dark side)
- Cable bracket replace (dark side)
Wed Jul 27 10:09:51 2022, Koji, General, General, 4+4 wire clamp in hand
- 4 CLASS A wire clamp obtained from the OMC spare
- 4 more DIRTY wire clamp obtained from WB experiments (they no longer use these)
Once the later ones are C&Bed, we have enough.
Wed Jul 27 10:34:09 2022, Koji, General, General, High QE PD: QE measurements 2
- DLPCA-200 trans-impedance amplifier was calibrated.
Keithley source meter 2450 was connected to the amp. Provide current and read the output voltage with the precision digital voltage meter (Agilent/Keysight).
Gain: 999.7V/A@7mA, 999.6V/A@8mA
- From the power meter spec, Thorlabs S401C seemed the best (+/-3%). So the QEs of the 9 PDs were checked with this power meter again.
- All PDs exhibited the QE of 0.95~0.96. It's all relative as the power meter has a systematic error.
- Tried to clean B1-22 and B1-23 PDs. They didn't show significant improvement after the cleaning. To avoid the unnecessary risk of damaging the PDs, further cleaning was not performed. (Some photos were attached)
- What we can do is use this result as the relative measurements.
- For OMC#2, B1-22 is the DCPD(T) and B1-23 is the DCPD(R). C1-03 and C1-12 are the spares, according to this latest result.
- At LLO, we track down the source of the throughput reduction (-10%). The QEs of the PDs are going to be tested in the same setup at once to compare their PDs and our PDs.
||July 26, 2022
||clean1 / installed (T)
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||clean1 / installed (R)
||July 26, 2022
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||July 26, 2022
||July 26, 2022
Wed Jul 27 10:34:30 2022, Koji, General, General, OMC #002 Protective FirstContact Paint
The optical surfaces were coated with FirstContact to keep them clean / somewhat protected during the transportation.
The PD aperture was sealed with FirstContact "caps" (made by Kate in 2016?).
Wed Jul 27 23:52:18 2022, Koji, General, General, OMC #002 Cable bracket replacement (1)
- D1300052-V3 SN001 is going to be used (Attachment 1)
- This is the PEEK version of the cable bracket (Attachment 2). The side thread holes have no Helicoils inserted. This needs to be done!
Connector arrangement check / cable routing check
Attachment 3: Connector Arrangement from the Northside
Attachment 4: Connector Arrangement from the South side
Attachment 5: Cable routing (Northside down)
At this point, the delamination of the V shape beam dumps was visible. This is the subject of bonding reinforcement.
Thu Jul 28 00:28:15 2022, Koji, General, General, OMC #002 Cable bracket replacement (2)
- (Attachment 1) The connector nut rings were removed using an angled needle nose plier. The connector shell has a tight dimension relative to the hole on the bracket. But of course, they could be extracted.
- The 4 screws mounting the bracket to the invar blocks were successfully removed. No extra damage to the bonding.
- (Attachment 2) The plan was to remove the cable pegs by unfastening the button head 1/4-20 screws from the bracket and then just replace the bracket with the new one. However, these screws were really tight. The two were successfully removed without cutting the PEEK cable ties. Two cable ties were necessary to be cut to detach the bracket+pegs from the fragile OMC. Then one screw was removed. However, the final one could not be unfastened. This is not a problem as we are not going to recycle the metal cable bracket... as long as we have spare parts for the new bracket.
- (Attachment 3) Right now, the new bracket is waiting for the helicoils to be inserted. So the OMC lid was closed with the cables piled up. Just be careful when the lid is open.
Thu Jul 28 00:46:47 2022, Koji, General, General, Subject: OMC #002 Cable bracket replacement (3)
Checking the spare parts
- Conclusion for OMC#2: need PEEK cable ties
- for more OMCs: need more BHCS / PEEK cable ties / Helicoils
- Helicoils: 1/4-20 0.375 helicoils / Qty 4 / Class A (Attachment 1)
- looks like there are many more as the transport fixture bags (Attachment 2). Stephen noted that they are meant to be CLASS B
- Cable pegs: D1300057 / Qty 24 + 3 recycled from OMC#2 / Class A (Attachment 3)
- Requirement: 3+3+4 = 10 for the 4th OMC / 3x4 =12 for the cable bracket replacement -> we have enough
- PEEK Cable Ties: Stephen reported they were deformed by baking heat... did not check how they are in the bags.
- Button Head Cap Screws 1/4-20 length ? none found in the bags.
- Qty 4 spare (forgot to take a picture) + 3 recycled. So we have sufficient for OMC#2
Wed Aug 10 18:42:27 2022, Koji, General, General, OMC #002 Cable bracket replacement (4)
Now we got the C&Bed parts to continue to work on the cable bracket replacement.
1) Helicoil insertion
1/4-20 Helicoils were inserted into the 6 thread holes of D1300052. It went mostly okay. We witnessed that the Helicoil insertion tool delaminated the plating of the Helicoils upon insertion (Attachment 1). Stephen mentioned that this is not usual, but we didn't find anything further such as increased friction, more debris, etc. So we decided to go forward.
2) EP30-2 Kit
The EP30-2 kit was transferred from the 40m clean room to the OMC lab. The EP30-2 kit tracking was updated via C1900343
3) D1300052 reinstallation -> FAIL
Now resumed to the installation of D1300052 bracket. However, the hole size of the bracket is just a bit too small compared with the size of the mighty mouse connectors. It was already quite tight with the metal version. However, this PEEK version seems to have 0.1 mm further small diameter, and then the connectors do not penetrate the holes. The plan could be
1) Use a razor blade to shave the hole inner circle.
2) Use a cleaned drill bit to make the hole size 0.2mm bigger.
Thu Aug 11 15:24:57 2022, Koji, General, General, OMC #002 Cable bracket replacement (5)
- The hole size extension is going forwared now.
- Madeline and Chub are cleaning (sonicating) a drill (29/64=0.4531")
- The parts in a bag were brought to the 40m C&B lab.
- The hole is going to be 11mil=0.28mm larger than the recommendation (0.442").
It's not a D-hole. The connector has a rounded-rectangular flange that fits into the PEEK parts.
So I don't think it's an issue.
- Chub has a proper spanner to fasten the nuts. We want to use it here and LLO.
Mon Aug 15 21:31:56 2022, Koji, General, General, OMC #002 Cable bracket replacement (6)
The cable bracket was successfully replaced.
- Looking from the QPD side (North side in Attachment 1), the connectors for the DCPDs and PZT are sticking out, and the ones for QPDs are sticking to the other side. So only two rectangular holes (for QPDs) are facing north.
- Top left is DCPDT
- Top right is DCPDR
- Bottom center is PZT
- Bottom left is QPD (far/long)
- Bottom right is QPD (near/short)
- First, the cable pegs for the short sides are fastened with the original screws (Vented BHCS 1/4-20).
- Then, the cables are started to be inserted from the bottom so that the nuts can be rotated with the spanner. The spanner helped a bit but the nut only has two positions to hook the spanner and the clearance is not sufficient to insert the spanner when one of the hook positions is facing the bottom. The enlarged hole (29/64") perfectly worked . The flange of the connector can be held with a rectangular hole, so a bit bigger hole than the connector size was not an issue. Finally, all the cables were attached to the bracket.
- The bracket has not yet been fixed on the OMC breadboard yet. This was done with the four screws from the top. Along with the assembly document E1300201, the fastening torque was limited to 2 in-lb using a digital torque wrench.
- Attachment 2 shows the view from the "North" side. Attachment 3 shows the view from the "South" side. The cables were not yet tied on the cable pegs on the long side of the bracket.
Mon Aug 15 22:06:18 2022, Koji, General, General, OMC #002 new cable tie installed
New cable ties were installed on the cable pegs attached to the long sides of the cable bracket.
Mon Aug 15 22:43:35 2022, Koji, General, General, OMC #002 Delamination repair Part1 (1)
Checked the delamination status:
- The Invar bar on the cable bracket (DCPD side): Almost all delaminated (Attachment 1 left)
- The invar bar on the cable bracket (QPD side): Rims still intact, center delaminated (Attachment 1 right)
- The invar bar reinforced in 2016: One of the reinforcement bar half delaminated (Attachment 2)
Mon Aug 15 22:49:03 2022, Koji, General, General, OMC #002 Delamination repair Part1 (2) 7x
- Two Al foil cups + A sheet of Al foil (for test cure)
- Set a tube on the glue gun
- Attach an applicator tube
- Push a couple of times, and dispense the glue for a single stroke on a waste Al cup
- Pour the 6g of glue to the other cup.
- Add 0.3g of silica beads powder to the cup
- Steer. Pick a few drops to the test cure Al foil
- Bake the test piece for 15min in 200F (95degC) ==> Very good
#1 The Invar bar on the cable bracket (DCPD side)
Added short (frosted) Al bars (Attachment 1) to the short sides of the invar bar. (Attachments 2/3). Some glue was sucked into the delamination gap by capillary action (=good) (Attachment 4)
#2 The Invar bar on the cable bracket (QPD side)
Added short (frosted) Al bars to the short sides of the invar bar. (Attachments 3/5). Maybe some glue was sucked into the delamination gap??? Not so clear. (Attachment 4)
#3 The Invar bar reinforced in 2016
Added a short (frosted) Al bars to a short side of the invar bar (Attachment 6). On both sides of the 2016 reinforcement, rectangular prisms are added (Attachment 6)
Some capillary action is visible beneath the invar bar (Attachment 7)
Leave it as it is for a day
Wed Aug 24 02:51:23 2022, Koji, General, General, OMC #002 Delamination repair Part1 (3) 8x
Inspection of the bonding on the suspension interface side. All look good.
Wed Aug 24 02:53:46 2022, Koji, General, General, OMC #002 Delamination repair Part2 (1)
Inspection of the delaminations in the optics side
Wed Aug 24 02:57:43 2022, Koji, General, General, EP30-2 bonding setup
EP30-2 bonding setup
Wed Aug 24 03:20:59 2022, Koji, General, General, OMC #002 Delamination repair Part2 (2) 11x
Wed Aug 24 03:26:43 2022, Koji, General, General, OMC #002 Delamination repair Part2 (3) 8x
Wed Aug 24 11:29:47 2022, Koji, General, General, OMC #002 ready for shipment
The OMC #002 is ready for shipment.
Attachment 1: Work done on Sept 19, 2022
Other attachments: Putting the OMC in the pelican case.
Thu Aug 25 14:22:08 2022, Koji, General, General, LLO OMC #001 Ballast Mass investigation
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.