 Tue Aug 22 15:51:15 2023, Koji, General, General, Inventory: C30655 PDs
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During the OMC(004) assembly, the stock situation for Excelitas C30655 PDs was checked.
PD Cage H
Slot 1: Laser Components 3mm -> |
 Mon Nov 27 21:05:51 2023, Koji, General, General, Inventory: C30655 PDs
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The Cage H&I, as well as OMC DCPD bag, were brought to the 40m for the 40m BHD.
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Mon Nov 13 23:57:55 2023, Koji, Electronics, Loan / Lending, Agilent 4395A Network Analyzer -> WB251
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Aidan and Hanna wanted to use the Agilent 4395A Network Analyzer at the WB251.
All the connections were removed. Unrelated units including an HP FFT analyzer and the Linux PC were also removed. |
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Mon Sep 18 15:09:55 2023, Thejas , Optics, CAvity Bonding, Piezo inertial micromaters
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New piezo actuated micrometers from thorlabs arrived last week.
4 x MPIA10
1 x KPS201 |
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Mon Sep 18 15:08:26 2023, Thejas , Optics, General, OMC HEPA enclosure filter fan speed
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I went in lab today and turned the HEPA filter (clsoe to the entrance) to high since we are not doing any measurements at the moment.
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Thu Sep 14 14:26:51 2023, Camille Makarem, Electronics, Characterization, Remaining PZT tests
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PZTs 31, 32, 35, 40 and 45 have had their DC responses measured (pre-reliability test) and have been through the reliability test (see 564).
We still need to measure their DC responses post-reliability test.
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Wed Aug 30 12:38:52 2023, Thejas , Optics, General, A+ OMC #1: HOM spectrum
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Examination into bonding template confimred the limitation of space available to change cavity length by at least 10 mm to improve the cavity HOM
spectrum. Here's an anlysis of HOM spectrum for various possible ROCs and corresponding required cavity length change for optimum HOM spectrum.
Assume: Astigmatism: Rx-Ry = 8mm |
Fri Aug 25 22:01:29 2023, Koji, Facility, General, LED Strip installation plan 
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| Here are the dimensions of the LED strips and their gaps. |
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Tue Aug 29 16:54:46 2023, Koji, Facility, General, LED Strip installed
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[JC, Koji]
We've installed the LED strips on the HEPA frame. We tried not to touch the OMC there. But please check if everything is still ok.
Attachment 1: Installed LED light. Notice the room light is off. At the max brightness, it's still sufficient to work with |
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Thu Aug 24 16:09:46 2023, Camille Makarem, Optics, General, PZT length-to-angle coupling
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[Camille, Thejas]
We checked the length-to-angle coupling of each PZT by monitoring the position of the transmitted beam on the CCD camera. The CCD camera was placed |
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Thu Aug 24 12:30:58 2023, Camille Makarem, Thejas , Optics, Characterization, FSR and TMS analysis
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Attached are the analysis results from the measurements in 616.
FSR: 264.657354 +/- 0.003444 MHz
Pitch TMS: 58.45691858660249 MHz |
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Wed Aug 23 07:48:14 2023, Camille Makarem, Tejas, Optics, Characterization, FSR and TMS measuarement of A+ build
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[Camille, Thejas]
22 August 2023
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Mon Aug 21 07:59:40 2023, Camille Makarem, Optics, General, cavity realignment and new power measurements 6x
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[Camille, Thejas]
18 August 2023
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Mon Aug 21 15:02:32 2023, Koji, Optics, General, cavity realignment and new power measurements
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This is WOW!
Excellent mode matching work.
The measurement is still consistent with the low loss even with the different mode-matching level. |
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Mon Aug 21 16:05:07 2023, Camille Makarem, Optics, Characterization, cavity realignment and new power measurements
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Thanks for clarifying that. We will repeat some power measurements and check the output offset voltage to the laser.
Quote:
This is WOW! |
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Mon Aug 21 16:15:09 2023, Koji, Optics, Characterization, cavity realignment and new power measurements
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You should proceed to the next steps. You'll need to repeat the power measurements before the bonding. Next time, the measurement procedure will
be improved. |
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Tue Aug 22 10:25:10 2023, Thejas, Optics, Characterization, cavity realignment and new power measurements
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Thanks Koji, we did observe this discrepency and thought that the code normalizes the power/voltage readings to the reference power value. We will then
proceed towards FSR and TMS measurements today.
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Thu Aug 17 09:06:51 2023, Camille Makarem, Optics, General, realignment of beam path through mode-matching lenses
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[Camille, Thejas]
16 August 2023
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Thu Aug 17 07:57:12 2023, Camille Makarem, Optics, General, mode-matching in the cavity
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[Camille, Thejas, Koji]
16 August 2023
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Tue Aug 15 16:15:13 2023, Camille Makarem, Optics, General, new power measurements (after cleaning)
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[Camille, Thejas, Masayuki]
This afternoon we finished the realignment that we started after the FC cleaning in https://nodus.ligo.caltech.edu:8081/OMC_Lab/605. |
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Mon Aug 14 14:13:34 2023, Camille Makarem, Optics, General, mode-mismatch in the cavity
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For Set 1 of the data in https://nodus.ligo.caltech.edu:8081/OMC_Lab/604,
VREFL(unlocked) = 3.226V
VREFL(locked) = 0.13V |
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Mon Aug 14 07:52:11 2023, Camille Makarem, Optics, General, 2nd cleaning of the cavity optics
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[Camille, Thejas]
11 August 2023
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Fri Aug 11 10:42:05 2023, Camille Makarem, Optics, Characterization, power budget measurements
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[Camille, Thejas]
10 August 2023
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Thu Aug 10 12:33:42 2023, Camille Makarem, Optics, General, optimizing the cavity post-cleaning
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[Camille, Thejas]
This morning, we continued the efforts from http://nodus.ligo.caltech.edu:8080/OMC_Lab/602. |
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Wed Aug 9 17:00:52 2023, Camille Makarem, Optics, General, cleaning the cavity optics
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[Camille, Thejas]
We inspected surfaces of the cavity optics with a halogen lamp and noticed a particulates on optic HR surfaces. We cleaned all 4 optics |
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Wed Aug 9 07:47:21 2023, Camille, Thejas, Optics, General, steering the beam spot on the curved mirrors 7x
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[Camille, Thejas, Masayuki]
8 August 2023
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Tue Aug 8 07:39:17 2023, Camille Makarem, Optics, General, steering the beam spot on the curved mirrors
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[Camille, Thejas]
7 August 2023
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Tue Aug 8 10:42:11 2023, Thejas, Optics, General, steering the beam spot on the curved mirrors
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The spots look quite bright on the CMs, we need to move the spots towards the center of the mirorrs to avoid scatter points.
Quote:
[Camille, Thejas] |
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Tue Aug 8 07:30:49 2023, Camille Makarem, Optics, General, REFL CCD image
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[Camille, Thejas]
7 August 2023
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Tue Aug 8 09:38:14 2023, Koji, Optics, General, REFL CCD image
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It has a higher-order mode, but you can still extract TEM00 from this beam.
e.g., See a past reflection image in Attachment 4 of this entry. In this case, it's
apparently difficult to extract more TEM00 mode from this spot. |
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Mon Aug 7 16:01:05 2023, Koji, General, General, OMC (004): Production completed
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| OMC (004) Production completed. The OMC together with the transport fixture is still placed at the 40m clean room. |
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Thu Aug 3 15:04:26 2023, Stephen, General, General, aLIGO Unit 4 Build, Cable Routing, Preparation
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[Dean, Stephen]
Unit #4 aLIGO OMC unit was transported to the 40m Bake Lab.
We unwrapped the Transport Fixture and identified the orientation which would place the Light Side up and accessible. We removed the 4 long SHCS |
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Mon Aug 7 16:00:30 2023, Koji, General, General, OMC (004): Cable installation
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The writing of this elog is still on going
[Dean, Stephen, Koji]
4th OMC production was completed.
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Mon Aug 7 07:40:33 2023, Camille Makarem, Optics, General, optimizing reflected signal
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[Camille, Thejas] 4 August 2023
-REFL PD signal (unlocked): 3.5V |
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Mon Aug 7 08:37:59 2023, Koji, Optics, General, optimizing reflected signal
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With the current level of the mode matching, the spot positions can be optimized. I'd work on it first as the mirror RoC and loss depends
on the spot positions on the curved mirrors.
---- |
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Mon Aug 7 08:51:56 2023, Camille Makarem, Optics, General, optimizing reflected signal
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We will plan to look at the reflection CCD image this afternoon.
Quote:
With the current |
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Mon Aug 7 07:36:09 2023, Camille Makarem, General, General, particle count
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[Camille, Thejas]
We lowered the setting to MEDIUM on the HEPA furthest from the entrance. (The two HEPA settings are now LOW and MEDIUM.) We measured the particle |
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Thu Aug 3 15:15:29 2023, Thejas, Optics, General, A+OMC mode-matching efficiency
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The cavity falls out of lock very often when subjected to slight movements of objects on the optic table. On Wednesday, we tried
to bring the cavity back to resonance when one of the curved mirrors' position was slightly disturbed. And now the reflected cavity power is higher
than that achieved on Tuesday (see below). This means mode-matching efficiency is about 96.5%. The laser control signal and reflected PD signal also seem noiser |
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Thu Aug 3 15:24:28 2023, Koji, Optics, General, A+OMC mode-matching efficiency
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The amount of the reflected beam is a function of the mode matching and the cavity loss.
- The noise could show up larger when the PDH lock has the error offset. Try to tune the input offset knob (which has no knob dial ;) ) to minimize |
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Thu Aug 3 07:22:19 2023, Camille Makarem, General, General, particle count and cavity optimization/alignment
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Yesterday, we measured the particle count in the enclosure to ensure that the lower setting on one of the HEPAs is still acceptable. The
particle count is still zero for all measured particle sizes (0.3um, 0.5um, 1.0um, 2.0um, and 5.0um).
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Thu Aug 3 09:42:36 2023, Thejas, Optics, General, OMC Lab HEPA air filter noise
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Koji mentioned that previously sarisfactory particle count was not acheived with the Med/Med HEPA filter setting once the enclosure was expanded, so
a higher setting was used. This imparted noise to the cavity from the turbulent air flo. We noticed that the noise level in the laser control
signal reduced with turning the HEPA filter next to the entrance to low and the current setting is Low/High. The particle count is zero (as below). |
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Thu Aug 3 10:31:55 2023, Thejas, Optics, General, A+ OMC build: beam spot positions
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Quote:
Yesterday, we measured |
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Wed Aug 2 07:32:28 2023, Camille Makarem, Thejas , Optics, General, Setting up electronics and locking the cavity
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[Camille, Thejas, Masayuki, Koji]
Previously, we were using the function generator to drive the laser without using the servo module. On Tuesday, we incorporated the servo module
(output from function generator to sweep input). Slow laser freq scan: 8Hz, 3 Vpp ramp. We were able to see the TEM00 mode after increasing |
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Tue Aug 1 11:04:13 2023, Camille Makarem, General, General, reoptimizing cavity alignment before locking
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[Camille, Thejas]
We rechecked the alignment this morning and re-optimized the resonance a bit. There was some horizontal drift in the alignment from yesterday.
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Mon Jul 31 13:19:14 2023, Camille Makarem, General, General, plans for this week 31 July 2023
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Plans for this week:
1) Verify electronics setup for cavity locking.
Current state: Output from function generator is going directly to laser driver (not currently using the Newport Servo |
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Sat Jul 29 12:05:52 2023, Thejas , Optics, General, A+ OMC unit 1 build: Resonance achieved
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[Camille, Thejas]
Steps followed to acheive this resonance:
1. Make sure the input beam is roughly aligned to the center of the flat mirrors (FMs). The height of the beam should be roughly the height |
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Wed Jul 26 15:01:26 2023, Madeline Lesovsky, Optics, General, Subassembly Bonding Effort - Oven Bake Profile Results
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The bonding efforts were conducted on Thursday, July 13, 2023 (https://nodus.ligo.caltech.edu:8081/OMC_Lab/561)
The duration of the air bake in ABO A was recorded and results can be found in the graphs below. The raw data can be found in the .xlsx file.
Post-bake log (https://nodus.ligo.caltech.edu:8081/OMC_Lab/563) for reference. |
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Wed Jul 26 12:14:53 2023, Camille Makarem, Optics, Configuration, Swapping Subassemblies
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While using mirror SN14 and mirror SN30 for CM1 and CM2 respectively, we monitored the two beam spots on FM2 and continued to see ~5mm of vertical displacement
between the two spots. We swapped the subassembly containing SN30 for the one containing SN02 and we see that the pitch misalignment is resolved. We will
proceed to lock the cavity using the following mirrors: |
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Tue Jul 25 23:39:07 2023, Thejas, Optics, General, A+ OMC unit 1: CM positions swapped
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With CM #30 at CM1 position and CM #14 at CM2 postion, when the beam spot on the CM1 is a little lower than the central line the spot position on the
CM2 is higher. This not expected given that the ROC of these mirrors is large. We swapped the position of these mirrors and the spot positons on these
CMs is not consistent i.e. whne the spot on CM1 is lower the same is true for CM2. But we see that the first reflection spot from FM1 is higher than |
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Fri Jul 21 13:42:10 2023, Thejas, Optics, General, A+ OMC Unit 1 Cavity Build
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7/21/23
Fringes were observed at the optic-breadboard interface. This was eliminated by cleaning the interface with IPA while making sure the coated
surfaces are untouched. |
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Mon Jul 24 16:12:14 2023, Koji, Optics, General, A+ OMC Unit 1 Cavity Build
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It is ~1mm from the zero of the micrometer readings. See attached photos from the 1st OMC build.
In the end, we'll use the FSR measurement to finely adjust the cavity length, but let's try to make them as symmetric as possible.
i.e. if you need 0.4mm shrink of the cavity roundtrip length, move CM1 and CM2 by 0.1mm each. |
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Mon Jul 24 17:43:25 2023, Koji, Optics, General, A+ OMC Unit 1 Cavity Build
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Thanks Koji
Quote:
It is ~1mm from the zero |
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Mon Jul 24 17:39:06 2023, Thejas, Optics, General, A+ OMC Unit 1 Cavity Build
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7/24/23
The cavity input was re-adjusted to make sure the beam was parallel to the breadbaard and close to the cavity axis. Beam spot on the CM1 is
about a mm off from the centre, clsoer to the FM1. The opposite was seen for CM2. This is desirable. But we also observed that the spot was lower that |
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Tue Jul 25 11:03:13 2023, Thejas, Optics, General, A+ OMC Unit 1 Cavity Build
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This readjustment to the input beam involved adjusting the persicope mirorrs and sterring mirror. We estimate that this will have changed the waist position
by approx. half an inch, a compensating adjustment to the position of the transport fixture will be made eventually.
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Thu Jul 20 14:28:53 2023, Thejas , Optics, General, A+ OMC optic bench beam layout
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Beam profile of the input beam was measured at it's beam waist, this is to ensure the input beam waist matches the cavity beam waist (mode-matching)
- ref attachement 2
w_0x: 456.47032902662903 +/- 1.4466927709703827 um
z_0x: 0.35828846919253937 +/- 0.008323313108283267 m
w_0y: 495.1490367020396 |
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Fri Jul 21 03:29:30 2023, Koji , Optics, General, A+ OMC optic bench beam layout
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Nice measurement. This result suggests that the fiber mode is supposed to be matched to the OMC cavity by 99.8% at z0=0.358 m. Note that the OMCmode
has a waist radius of 0.4896 mm and 0.4905 mm for the horizontal and vertical modes, respectively.
In reality, the fiber mode contains higher-order HG modes. Therefore the actual mode matching will be limited to ~98%. |
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Fri Jul 21 00:23:35 2023, Thejas , Optics, General, A+ PZT subassembly glue sheets
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| Below are the gluesheets for the first four PZT subassembly bonding. |
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Fri Jul 21 00:07:03 2023, Thejas , Optics, General,
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[Camille, Thejas, Stephen]
Effort was made to coarsely align the laser beam into the caivty
FM1: #17 (wedge angle: 0.4788 deg, deviaiton from perp: 5.7 arcsec acute) |
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Thu Jul 20 14:14:49 2023, Thejas , Optics, General, A+ OMC bonding template alignment
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We aligned the bonding template onto the glass braedboard. This was done with the help of a vernier caliper and adjusting teh peek screws at the edge
of the templates to make sure that the gap between the breadboard and template edges are equal for each pair of opposite sides.
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Tue Jul 18 17:34:45 2023, Thejas, Optics, General, A+ PZT sub-assemblies
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[Camille, Thejas]
Post sub-assembly bonding of CM : Madeline will post a separate update on the Oven temperature profile.
The subassemblies were taken out of the oven. The bonding fixture plates were carefully taken apart, sub-assembly #1 involving curved mirror |
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Wed Jul 19 14:26:17 2023, Koji, Optics, General, A+ PZT sub-assemblies
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| Pens like Sharpie are not recommended to be used for CLASS B parts. |
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Wed Jul 19 11:00:56 2023, Thejas , Optics, General, A+ OMC Bonding
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[Camille, Thejas]
The A+ OMC transport fixture and optic breadboard was transported to the OMC lab. They were cleaned thouroughly using high grade IPA red
wipes after using a nitrogen gun to blow away contaminants (carefully away from rest of the optics on the bench). The breadboard was examined under |
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Wed Jul 19 08:38:07 2023, Camille Makarem, Electronics, Characterization, PZT Reliability Test Results (part 2 of 2)
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Results for PZT reliability test:
Batch 3: SN31, SN32, SN35, SN40, SN45
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Mon Jul 17 10:15:56 2023, Camille Makarem, Electronics, Characterization, PZT Reliability Test Results (part 1 of 2) 10x
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[Camille, Thejas, Stephen]
Results for PZT reliability tests:
Batch 1: SN37, SN38, SN39, SN44 |
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Thu Jul 13 01:02:58 2023, Stephen, Optics, General, A+ OMC, Bonding of Curved Mirror Batch 1 16x
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[2023.07.13 - Stephen, Camille, Thejas, Maria]
We bonded Curved Mirror assemblies today. Some notes about this log entry:
Thejas will post a log discussing matching.
This log hosts a subset of the photos posted to the A+ |
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Thu Jul 13 00:38:47 2023, Stephen, Optics, Characterization, A+ OMC, PZT DC Response and Length to Angle before Curved Mirror Assy Batch 1
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[2023.07.13]
The attached table includes the characterization values used to inform the matches for the first four units, Curved Mirror Assy Batch 1.
Thejas prioritized the matches using these insights. Some notes: |
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Wed Jul 12 17:27:44 2023, Koji, General, General, Mitsutoyo Digital Caliper (100mm)
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| We had missing digital caliper from the clean room. As it is an essential component, I have ordered a replacement. |
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Mon Jul 10 20:52:19 2023, Koji, Optics, Characterization, OMC (004) TMS measurement
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| Belated entry: OMC(004) TMS measurement with the PZT voltages scanned (Jun 12/15, 2023) |
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Thu May 11 10:46:17 2023, Thejas , General, Characterization, aLIGO OMC
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[Thejas, Camille, Koji]
We aligned the laser beam to the cavity and drove the OMC cavity PZTs (0 to 5 V from signal generator with 15x amp from the piezo driver) with
a ramp signal and logged the transmission mode spectrum. The drive PZT voltage changes from 3.4 V to 7 V for one fringe shift or half wavelength change |
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Mon Jul 10 20:29:05 2023, Koji , General, Characterization, OMC(004) PZT characterization
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Belated entry: OMC(004) PZT Slow scan / freq response measurements (May 10/11/17, 2023)
PZT DC scan measurement showed that CM1 had a significantly larger response than the usual PZT responses, and CM2 has the one significantly less.
The measurements were repeated and the same result was confirmed. |
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Mon Jul 10 20:23:47 2023, Koji, Optics, Characterization, OMC (004) Spot positions 10x
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Belated entry: OMC(004) Spot positions (Jun 15, 2023)
Photographs of the spot positions on the cavity mirrors and the DCPDs/QPDs as well as the reflected beams towards the beamdumps. |