drift calculation for the SMA100A, posted by Ronic Chiche at ThomX igloo about lasers and optics 
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the goal is to estimate what could be the frequency drift at 500MHz for the SMA100A: see phase noise datasheet in attachement
Sphi(f) = FFT ( Rphi(T) ) = FFT ( < Phi(t) Phi(t+T) > )
at low frequency, Sphi(f) ~ A / (f^n) = A*(2pi)^n / (i2pi*f)^n => Rphi(T) = A*(2pi)^n*T^(n-1) / (n-1)! |
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Laser FP operation, posted by Daniele Nutarelli at Optical room about lasers and optics
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This morning FP Laser was operating well locked at 30 KWatts in stable vay.
There are some fluctuations due tu pointing instabilities probably dues to temperature fluctuations in de bunker.
In the attacced picture are reported the lock parameters and signals. |
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Tests of pointing stability of the laser CFP, posted by Daniele Nutarelli at ThomX igloo about lasers and optics
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Last monday with Victor we have cheked the stability of de pointing of the laser FP.
The climatisation was operating since 3 days in satble way. The laser pointing was very stable before to inejct in to the cavity (picture 1)
and also for the reflexion from the cavity (picture 2). |
Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics
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Today, the power measured at the input of the amplifier (PD_IN on the LAL amplifier software) is 2.5mW instead of >3mW generally measured
The power coming from the NKT/Onefive Origami oscillator is still >37mW (measured directly with the powermeter at the laser output without
OD2). |
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Temperature control of the Laser length with the inside Peltier, posted by Ronic Chiche at ThomX igloo about lasers and optics
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bunker temperature @ 22.5°C
today, Sebastien Pitrel improved its python software to manually control the laser peltier. |
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FP-cavity inside power sensitivity, posted by Ronic Chiche at ThomX igloo about lasers and optics
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this morning I monitored the frequency shift between the FP-cavity frequency (the laser is locked on it) and the RF reference frequency @ 500MHz,
during the warm-up time, for 50kW stored in the cavity (the recording started ~ 9h20).
one observes on fig.1 a simple exponential behavior with 500Hz frequency shift @500MHz (equivalent to ~ 10µm) for 50kW stored. |
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New mirrors batch informations, posted by Ronic Chiche at ThomX igloo about lasers and optics
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| the 2 files describe the specfications for the16 mirrors ordered (4 for ThomX + spare, 4 for SBOX + spare) and the measurements made by the LMA. |
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Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics
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today, the Alphanov amplifier stopped because of the too low injected power : ~2.5mW (measured by the Alphanov software)
it was still working at ~2.7mW.
normally, the injected power is ~3.1mW (equivalent to 6.2mW measured directly at the fiber output). |
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Variable focal lens validation, posted by Ronic Chiche at ThomX igloo about lasers and optics
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we plan to use Electrically Tunable Lenses EL-10-30-C NIR to build the ThomX telescope but they need to be compatible with the powerful laser beam.
for CW regime, on the datasheet (see attached file), the optical damage threshold is 10 kW/cm².
with 70W laser power and 1mm² beam surface (which is much smaller than the real beam size), we are at 7kW/cm². |
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New multiplication factor for the Fabry-Perot intra-cavity power, posted by Ronic Chiche at ThomX igloo about lasers and optics
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last week, we measured the transmission of a plan mirror from the same batch than the ThomX mirrors and we got ~ 1.75ppm instead of 3ppm which was the
calculated value by the LMA.
previously, we put 1/3ppm = 333 333 as multiplication factor. |
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Alphanov amplifier issue, posted by Ronic Chiche at ThomX igloo about lasers and optics
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FYI : to access special menus on the Alphanov software,
login : "Administrator"
pwd : no password |
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Alphanov amplifier issue, posted by Ronic Chiche at ThomX igloo about lasers and optics
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the present situation is :
Guillaume asked me to disconnect the "Laser head" cable from the pump diode module, installed on the optical table.
on the pump diode module, the connector has several small pins and 3 larges pins : A1, A2, A3. |
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Alphanov amplifier issue, posted by Ronic Chiche at ThomX igloo about lasers and optics
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Guillaume and Julien Bour from Alphanov will come on wednesday 24/07 to have a first look and check the amplifier.
to prepare their intervention, I tested this morning the OneFive oscillator : it's still working at 33MHz.
and we have ~5mW in the LAL software without the EOM. |
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Alphanov amplifier issue, posted by Ronic Chiche at ThomX igloo about lasers and optics
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picture of the connectors used to carry signals between the amplifier pump module and the rack under the table.
DB13W3 standard has been used to carry high current on the 3 dedicated pins:
https://en.wikipedia.org/wiki/DB13W3 |
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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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Onefive 33MHz modelock loss, posted by Ronic Chiche at ThomX igloo about lasers and optics
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On Friday 11th of October, due to the Yvette flooding, all the AC power of ThomX have been shut down.
After the shutdown, I had to restart the Onefive oscillator but the laser modelock was lost.
I had to do a step of 1mm at 10mm/s with the Smaract motor on the rep rate channel (CH1) |
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Onefive 33MHz modelock loss, posted by Ronic Chiche at ThomX igloo about lasers and optics
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This morning, I verified the reason why the seeder frequency was not displayed on the amplifier software screen:
one needs to start the amplifier (even at 0%) to see the seeder frequency !!!
now, we have 33.371MHz as expected ! => OK |
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Onefive 33MHz modelock loss, posted by Ronic Chiche at ThomX igloo about lasers and optics
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After the new Yvette flooding of the last week and the consecutive AC-shut down, I restarted this morning the laser with the same procedure (step of
1mm at 10mm/s with the Smaract motor on the rep rate channel (CH1)).
now, we have again 33.371MHz and 3.1mW input power as expected ! => OK |
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Onefive 33MHz modelock loss, posted by Ronic Chiche at ThomX igloo about lasers and optics
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For the modulation/demodulation generator for the PDH signal,
after a power shutdown, on can :
1) restart the generator to get the correct parameters: |
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New power record in ThomX cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics
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| today, we were able to store more than 93kW in the FP cavity, always with the same parameter : 33% laser amplifier ratio |