Amplifier mission Bordeaux, posted by Loïc Amoudry at Other about mechanics | lasers and optics 
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M² mesuré à 10W.
M²x = 1.17
M²y = 1.14 |
Polarization, posted by Loïc Amoudry at Optical room about lasers and optics
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Polariztion measured with Input vertically/horizontally polarized (~100% DOLP)
- Transmission (P4) locked on cavity horizontal polarization is ~50% linearly polarized and ~50% unpolarized ?
- Transmission (P4) locked on cavity vertical polarization is ~50% linearly polarized and ~50% unpolarized ? |
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Onefive 33MHz unmodelocked, posted by Loïc Amoudry at Optical room about lasers and optics
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Oscillator randomly unmodelocked on 3rd july afternoon (during oscillator power measurement, maybe a reflection from the powermeter power filter
?)
Modelocked this afternoon by putting Onefive motor and phase at reference on the PTC software. |
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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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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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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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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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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 |
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Improvement holder amplifier fiber, posted by Loïc Amoudry at Optical room about lasers and optics
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| We've added a clamp in the 3rd stage to prevent the pump fiber from moving and tilting (it was tilting to the left). |
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Free Spectral Range (FSR), posted by Loïc Amoudry at Optical room about lasers and optics
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FSR is 33.347 MHz @1e-8 mbar
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Fiber injection and onefive output power, posted by Loïc Amoudry at Optical room about lasers and optics
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Fiber injection is finished with the new ThomX stretching CVBG in double pass (+50% injection power compared to K-BOX CVBG in simple pass).
- Output Onefive: 27 mW
- After Onefive + lambda/2 + isolator: 25.8 mW |
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Onefive spectrum and CVBG spectrum, posted by Loïc Amoudry at Optical room about lasers and optics
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| The Onefive spectrum has shifted a little bit to lower lambda. It's still enough for the experiment (3mW injection of ampli intead of 1mW needed). |
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First mode degeneracy on ThomX, posted by Loïc Amoudry at Optical room about lasers and optics
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Yesterday, we've observed the first degeneracy on ThomX cavity at ~115 kW stored. The shape of the stored power on the oscilloscope is really close
to what has been published in the D-shape mirror's paper ("tek0000" transmission in yellow, piezoelectric activator in green, error
signal in blue). |