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!!!!!!!!) |
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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First Lock with 2nd satge of amplifier : Finesse issue ?, posted by Ronic Chiche at Optical room about lasers and optics | detectors and electronics
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1st lock today with the second stage of the amplifier.
~ 300mW of injected power (but which proportion of the pump and of the signal ? => One must use a spectrometer to determine this proportion)
MAYBE the real injected power of the signal is lower => maybe the Finesse is higher ! |
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First Lock with 2nd satge of amplifier : Finesse issue ?, posted by Ronic Chiche at Optical room about lasers and optics | detectors and electronics
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First of all, we used and optical spectrometer to determine which proportion of pump and signal is in the injected beam.
the wavelength is THE SAME for the 2nd stage for the beam coming from the core or coming from the clad !
thus, it is impossible to use a spectrometer to obtain this proportion. |
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30Hz noise issue, posted by Ronic Chiche at Optical room about lasers and optics | detectors and electronics
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since some days, we observe the cavity is difficult to lock and a strange 30Hz noise has appeared on the PZT signal which normally compensate the phase
noise difference between the cavity and the laser.
to test if the problem could come from the laser, we changed the OneFive laser for the Koheras but we have exactly the same problem, thus we concluded |
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30Hz noise issue, posted by Ronic Chiche at Optical room about lasers and optics | detectors and electronics
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The 30 Hz noise issue has been solved !
It came from translation stage of P1 and/or P4.
Fabian remembered that close to the mirror's mount translation stage end coarse, there is a mechanical instability. The mount kind of "lift |
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FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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Installed and inputs:
CW laser ; power = 101 mW
PDH ;
at output
Low pass filter 50 ohm DC-1.9 MHz
at
input
freq = 8.4 MHz , Ampl = 1.2 V , phase = 160 /
voltage = ~ 6 V
EOM |
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FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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This afternoon, I did some alignment of the injection mirrors with a fast scan on the LaseLock to get a regular transmission photodiode signal.
the coupling increased to 10-15%
I got a first lock of the cavity only with the PZT. |
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FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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This morning with Manar, we installed the AOM+RF amplifier and the associated fast feedback loop.
Now the locking with the Koheras is good with a coupling of 20%.
Tomorrow is dedicated to the measurement of the Finesse.... we will have to add the 2nd EOM. |
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FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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Adding Oscilloscope images
delocked + locked intervals showing the 20% coupling
lock when the housing panels are closed + airflow on .
lock
when the housing panels are closed + air flow at lowest setting
an additional factor to the PZT voltage sensitivity |
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FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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Ending alignment series !!
Manar
Amer wrote:
Adding Oscilloscope images |
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FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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As it can be seen on the first plot, even with a good locking (good reduction of "high" frequencies noise: we had better locking than on the
picture) we still have very low frequency (~ 1Hz) fluctuations
these fluctuations prevent having a good measurement of the Finesse and they need to be understood. |
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Cavity Lock and Finess measurment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics 6x
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This morning, me and Ronic managed to obtain the FSR and image of the finesse which is to be analyzed.
Adding:
Beam Image at P4 propagation, no lens is added.
Image of the Finesse on Oscilloscope
more information to |
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FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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The fluctuation problem has been solved.
It was simply the new scheme to inject 2 RF frequencies in a single EOM.
It maybe produces some standing waves in the EOM RF input and creates some phase noise. |