2nd stage output power validated , posted by Loïc Amoudry at Optical room about lasers and optics 
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Onefive output power : 28mW
Power before fiber injection : 7.8mW
After EOM and 99% coupling fiber : 1.8mW |
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Spin coater air supply removed and front panel changed, posted by Loïc Amoudry at Optical room about mechanics | lasers and optics
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Spin coater firstly needed vacuum and air supply. The air supply being useless for our experiments, it has been disabled.
The process is the following and is reversible:
1) Remove the hub from the top of the spin coater, (see picture 1), 4 screws |
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Finesse measurement after mirror cleaning using the spin coater, posted by Ronic Chiche at Optical room about lasers and optics
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Last Finesse measurement in air : ~ 17 000 the 20th of may (see logbook)
28th and 29th of august, we cleanned, with Loïc, mirrors S3 then P1 successively using only ultra pure water with the spin coater.
we measured the finesse after each cleaning by modulation technique and in both cases, F ~ 12 500 !!! |
Finesse measurement after mirror cleaning using the spin coater, posted by Ronic Chiche at Optical room about lasers and optics
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today I cleaned S3 with isopropanol and then with pure water on spin coater.
Finesse is only 10 700.(coupling 50% ? => to be confirmed...)
maybe we have to redo the procedure with a different way of cleanig (pushing less on the mirror ... ?) |
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Motor issue, posted by Ronic Chiche at Optical room about mechanics | detectors and electronics
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Today, Axis 9 (Z-axis of P1) has blocked the software which drives all the motors.
impossible to bypass the problem.
I had to : |
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Vessel cleanliness, posted by Ronic Chiche at Optical room about mechanics | lasers and optics | vacuum
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looking in the vessel of the FP cavity using a UV lamp shows a lot of dust... more dust than outside the cavity !!!
here is picture where one can see a cleaned zone using a finger (with gloves).
question : where does come from this dust ? |
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Finesse measurement after mirror cleaning using the spin coater, posted by Ronic Chiche at Optical room about lasers and optics
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Following finesse measurements (start @10700):
Clean P1 with SC (water) + isoprop (wipe) finesse @15000
Clean S2 with SC (water) + isoprop (wipe) finesse @13000 |
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Mirrors sent to LMA, posted by Loïc Amoudry at Optical room about lasers and optics
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| Mirrors have been sent today to LMA for cleaning and maybe annealing (recuit). 3 ULE of ThomX and the fused silicate for injection (trans @140ppm ). |
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Primary vacuum to check dust, posted by Loïc Amoudry at Optical room about mechanics | vacuum
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The cavity has been cleaned then put under primary vacuum (primary pump without vacuum flow control). Dusts presence was checked at air and no significant
changes have been observed.
1ST image before cleaning |
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LMA cleaning technique, posted by Loïc Amoudry at Optical room about lasers and optics
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Christophe MICHEL told us more precise informations about spin coater cleaning.
They always clean with pur water and cotton tipped sticks.
First a spray of water, then they put the wet cotton tipped sitck onto the mirror from the center to the edge ~x3 while continuing to spread |
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Cavity dust source check, posted by Loïc Amoudry at Optical room about mechanics | lasers and optics
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Several experiments have been done in order to check the potential source of dust in the ThomX cavity. For each step, we look at a clean surface, put
the cavity under vacuum, go back at ambient pressure and check back the "clean surface".
1st: Primary pump on |
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Motor issue, posted by Ronic Chiche at Optical room about mechanics | detectors and electronics
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Today again, same problem with axis 9 blocking the controlling software during the mirror alignment procedure.
after opening the motor 9-16 controlling crate, we saw 2 screws (RX- and TX+ of the controller) which were badly screwed.
we firmly screwed them... could it be the cause ? |
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New Suprasil mirror from LMA, posted by Loïc Amoudry at Optical room about lasers and optics
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19/09/2019 : email from Chrisophe Michel about AR coating of LMA mirrors after reading that Ta2O5 layers can be damaged in vacuum if not protected by
a SiO2 layer :
"oui tous nos coating standards HR se terminent par une couche de protection SiO2 Lambda/2. |
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Finesse measurement, posted by Ronic Chiche at Optical room about lasers and optics
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After mirrors were going back from LMA for cleaning and thermal anealing, they have been installed in FP cavity for Finesse measurement.
after getting strange results when the cavity is closed (very low Finesse...maybe too much ethanol inside cavity procucing some lineic losses),
we get 12k-12k5 Finesse with primary vacuum (~4 mbar) and a clean lock (very flat transmission signal and quite noiseless reflection signal) |
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Diffusion ULE spherical mirror (S3) vs Fused Silicate injection planar mirror (P1), posted by Loïc Amoudry at Optical room about lasers and optics
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Observation made with IR Beam Viewer:
The observation of P1 and S3 simultaneously while locking shows much higher diffusion on the ULE mirror. The diffusion on the two other ULE mirrors
(S2 and P4) shows similar diffusion as S3. |
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Finesse measurement, posted by Ronic Chiche at Optical room about lasers and optics
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To complete these observations:
Finesse has been measured on thursday, right after cleaning the cavity with ethanol @6000.
Finesse has been measured on friday, after opening the cavity for few tens of minutes @12000-12500. The cavity was openned while |
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Pneumatic valves, posted by Loïc Amoudry at Optical room about mechanics
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| Frederic and Manu from vacuum group came this morning to fix again the pneumatic valves which had a leak again. |
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Cavity under vacuum , posted by Loïc Amoudry at Optical room about vacuum
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The cavity is right now at 6.5e-8 mbar (turbo pumps on for 1 night and ionic pumps for 3h), primary pumps and turbo pumps are cut, ionic pump are on
and the pressure level is still going down.
Therefore there aren't any big leak in the cavity and we can expect a final vacuum level close to e-9 mbar. |
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Electrical trouble (disjunction), posted by Loïc Amoudry at Optical room about cabling
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The circuit breaker on ThomX cavity drops @1.5-1.8kW when we turn on 1/2nd stage of the amplifier or 3rd stage of the amplifier.
Amplifiers are now connected to K-BOX UPS.
We are buying a clamp ammeter for further investigations. |
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ThomX amplifier M2, posted by Loïc Amoudry at Optical room about lasers and optics
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| The ThomX M2 has been measured between 1.5-1.6 for x and y |