End of cleaning, plastic fixed on cavity, posted by Loïc Amoudry at Optical room about utilities 
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| 08/02/19 - End of the cleaning process. |
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Electrons-Photons phase stability measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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we installed a measurement at the IP with the BPM for ion cleaning for electrons and we used a fast photodiode at the output of the FP-cavity and measured
with a fast oscilloscope the phase jitter between the 2 signals.
in red, the BPM signal |
Electrons-Photons phase stability measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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the phase between the 500Mhz ring RF oscillator and the electrons is measured on a BPM and is very stable after 2-3ms (<< 6ps, typically) !
in the same time, we can use the residual phase beating after our 500MHz mixer to estimate the phase noise coming from the laser part.
the rms noise of this signal is around 60mV for 1.25V peak (2.5 pk-pk) signal => ~ 50mrad rms |
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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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Détection de fuite, posted by Ronic Chiche at Optical room about vacuum
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Mail de Bruno Mercier du 18/10/2018 :
Un petit CR de la journée:
Nous avons effectué une détection de fuite sur l'ensemble des cavités optiques. Une fuite très importante a été |
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Documentation about mechanics on Atrium, posted by Ronic Chiche at ThomX igloo about mechanics
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https://atrium.in2p3.fr/0dded51a-1cb0-43e6-ae0d-626cd5db7078
a lot of schematics regarding the FP cavity are stored by the mechanic group on the Atrium repository. |
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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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Current Installed Setup, posted by Manar Amer at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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| Attached is the current setup in ThomX |
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Coating reflectivity, posted by Loïc Amoudry at Optical room about lasers and optics 6x
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| Coatings reflectivity curves and datas for HR Saphir, HR Suprasil and HR ULE. |
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Cleaning outside IP cavity, posted by Loïc Amoudry at Optical room about lasers and optics | utilities
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From 7th january to 11th january.
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Christmas shutdown, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software
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this morning, I shut off all the equipements (especially the computer) except the ones powered by the UPS : laser controller, laser peltier controller,
laser motors controller.
and I disconnected the cables from the power plugs of the wall (to prevent any possible overvoltage). |
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Christmas shutdown, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software
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this afternoon, I checked visually what happens when the AC power of the UPS is broken down => the laser controller has still its "emission"
button ON... no AC interruption.
so, I guess the UPS switched properly the output AC line from the input AC line to the internal batteries. |
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Checking the amplifier power, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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this morning, with Daniele, we checked the amplifier power, right after the CVBG (the power meter has to be placed on a metal plate above the large table
hole), and just at the input of the FP cavity, after the 1/4 and 1/2 waveplates (the power meter has to be placed on flat beam dump+ Thorlabs beam dump
+ V metallic mount to be at the right height). |
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Checking the amplifier power, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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we did a long term run (25 mn) with the powermeter located at the FPC position at 33% amplifier ratio.
the initial power was 18W .
then, it goes to 18.5W in 10 minutes, then 5 minutes later, it goes to 18.3W and stay stable until the end the run. |
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Checking the amplifier power, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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I put back and aligned the 1/2 waveplate only and I get 71kW max after its optimization and optimizing the CEP and alignment (without walking procedure).
this waveplate change a lot the reflected power seen on the CH2 of the scope.
to be continued this afternoon... |
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Checking the amplifier power, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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this afternoon, we put back the 1/4 and 1/2 waveplates and after a long alignment/angle tuning/CEP optimization process, we hardly got 80-81kW in the
cavity for 33% amplifier ratio. the transmission photodiode is then ~ 7.5 divisions (500mV/division) on the scope.
BUT during the 1/2 and 1/4 waveplate angle tuning process, we clearly saw: |
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Check of mirrors and coating directions, posted by Loïc Amoudry at Optical room about lasers and optics
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Direction of HR face of P1 and P4 have been checked, there was no problem. The mirrors are in the good direction and the coating is on the good face.
Once P1 and P4 outside of the cavity, we checked the coating position by sending the HeNe laser with an angle. There was two reflections and
the most intense was the one closer to the normal to the mirror. |
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Characterizing Focus Tunable Lens, posted by Fatematuj Johora at Optical room about lasers and optics
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Yesterday Ronic and I worked on the high laser power measurements with the Vertical set-up of the Focus Tunable Lens. We went upto 38W@4 dpt at the begining
and then also changed the focal power at 38W.
Observation: |
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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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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 |