Cavity Lock and Finess measurment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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to measure the Finesse, instead of having 2x EOM for the PDH and for the modulation sweep, I simply used 2x generators coupled with DC-blocks
to a T connector (SMA) screwed directly on the EOM input. |
Cavity Lock and Finess measurment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics 
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After changing the way of injecting modulation for PDH and modulation for FSR scanning (we split the modulations to 2 different EOMs), the locking
is very stable and we can measure the Finesse. |
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Cavity Lock and Finess measurment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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one thing which could reduce the Finesse is the L-shape metal piece if it is slightly inserted in the FP-cavity mode path.
understanding where this L-shape effectively is is not easy... some pictures are attached.
Manar |
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Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software
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This morning, while trying Guillaume solution of disconnecting the 24 V necessary to the second and third stage and raise the threshold of Temp preamp
1 (to only operate the ampli with first stage only)
Ronic disconnected the 24 volt connection, turned on amplifier LAL software but no MMD3 error or a big temp on Temp preamp 1 , software worked |
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Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software 13x
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Yesterday, with Ronic we locked ThomX cavity on the second resonance
Laser : 33.36 MHz , Amplifier : 0 % (worked with no errors all day)
adding image for the lock on the second resonance (locked), 00 Mode image, fit, Beam measurements |
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Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software
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Today, I installed a power meter at the transmission point of the 1st spherical mirror , transmission 3 ppm (direct from cavity window beam profiler,
no filter)
We locked the cavity at 2 different resonances of the fundamental mode, the lock in both cases was stable for a round 1 minute. |
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Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software
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Today with Ronic,
starting with major events that happened (Water circulation + ThomX valves )
Early in the morning a company worked on the water network, it seemed it was not restarted properly so there was no water circulation |
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Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software
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In the morning, we locked on the first resonance. With an increase on the amplifier power @ 20-25% and 30%, which reduced the noise
we manage to get a coupling when improving the CEP up to 55 - 60 % coupling : put there is still a drift on the CEP
The controller for the oscillator frep and CEP produces a lot of noise, even if it is disconnected. we need to switch it off to remove its effect |
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Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software
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The computer is possible to connect from the control room,
we are able to run remotely the amplifier, cavity motors, oscillator motors, lase lock (note: there is an issue with the keyboard, we are not
able to use it with remote access!!!!!!!!) |
Cavity Alighnment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics 9x
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Last week, with Ronic and Victor we aligned the cavity using CW laser (Koheras)
we have also installed 4 mirrors in the cavity with the best theoretical qualities (serial number and images included)
The
Plan ULE mirror P4 thickness was not compatible with the piezoelectric mount. We had to install a metal spacer behind the mirror |
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Cavity Alighnment , posted by Manar Amer at ThomX igloo about lasers and optics | vacuum | detectors and electronics
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Today, we prepared lenses for a telescope for the CW laser injection into the cavity, yet to be installed
Image of the transmission at P4 attached, an estimation of the beam size of the mode see is ~ 5.5 mm
The vacuum in the 2 optical cavities is decreasing but slowly. today it is 2.6 - 2.4 * 10^-7 mbar |
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CW laser installation and cleaning, posted by Ronic Chiche at ThomX igloo about lasers and optics
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This morning with Manar, in order to prepare the installation of the news FP cavity mirrors,
- we installed the Koheras below the optical table
- we put a fiber prolongator at the end of the Koheras fiber and we put a mounted collimator at the end of the fiber. |
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CW laser installation and cleaning, posted by Ronic Chiche at ThomX igloo about lasers and optics
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This morning with Ronic , in preparation for the mirror installation, we removed additional mechanics and cables from the table.
We organized and cleaned the permanently installed cables on the table away from the area of the cavity opening.
We opened the two top vents and left the shutters open to circulate clean air , (note the shutters surrounding the laser and amplifier are half |
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CW FP Cavit lock , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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Yesterday morning we locked the cavity on a strange mode in the cavity (we call it mode, but not sure what it is ??)
we also managed to lock on a higher order mode 02
we get an estimated 30% coupling (expected value), and note that we have not installed a telescope yet. |
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CW FP Cavit lock , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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This morning with Daniele and Viktor,
- we confirmed the "potato" mode was well centered on the injected beam and was not due to some misalignment of the injected beam compared
to the cavity axis. |
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CVBG reference and Eric Cormier calculation, posted by Loïc Amoudry at Optical room about lasers and optics
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The Stretcher is the "D 24-02-II", it must be used in double path before the amplifier injection.
There are two compressors in single path, "D 25-14-I" and "D 25-14-II".
Eric calculations are attached below. |
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CEM noise measurements, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | cabling
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The goal of these measurements is to check if one can find some correlation between the CFP lock losses observed during a run and some CEM noise in the
bunker.
the main issue is coming from a 20Hz noise apearing/disapearing in the laser cavity PZT signal. |
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CEM noise measurements, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | cabling
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This afternoon, we started almost all the parts of the machine with Vincent and Nicolas, and we didn't see any change in the Loop noise signal.
we saw only a peak comb at 10Hz on the Loop noise signal when the septum is ON. the amplitude of the peaks is then related to the voltage on the
septum. |
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Beam size at closest spherical mirrors position, posted by Loïc Amoudry at Optical room about lasers and optics
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S3 and S2 @ +1 640 000 and P1 and P4 @ -825 000
Diameter in x: 4.7mm
Diameter in y: 4.7mm |
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Beam size and finesse, posted by Loïc Amoudry at Optical room about lasers and optics
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FSR initiale : 33.34 MHz (S3 = -825000 et S4 = -825000)
Beam size initiale : wx=2.05mm et wy=2.15mm
Finesse initiale : 3400 |