Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software 
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we have had this new issue (watchdog alarm switching off the amplifier) for several days.
Alphanov mentionned it could come from the input oscillator stability (modelock loss for example).
Today, |
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Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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With Daniele after, we took a readings of the beam with a lens of 750 mm.
From the observed data, we can state that the beam is not completely Gaussian M2 > 1, due to the variation of the ellipticity of the beam
along the focused path |
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Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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This morning,
- with the "Alphanov" software => Central panel => "system" button => Watchdog "Period Max" was at 100ns
and has been set to 200ns. |
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Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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This morning with Daniele, we did a second measurement of the beam profile using a different lens of focal 400 mm.
at a power amplification of 20%
the amplifier stayed on for around one hour and a half with no errors. |
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Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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On Monday 20th of February, Daniele and Viktor took some beam profile measurement data @ 50% of power amplification.
data and analysis can be found in the attached file.
Ronic |
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Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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Yesterday, Guillaume Machinet and Vincent Clet from Alphanov came to fixe some issues with the laser amplifier:
- 1) they fixed the "rep. rate" measurement issue.
previously, the voltage range in which it was possible to detect the correct rep rate (33MHz) was very narrow ~ 50mV. |
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Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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This morning with Victor we took a reading of the beam profile using a 400 mm lens at 70 % and 100 % amplification.
Will process the data and add after
Note : after an hour and half of amplifier on at 70% we increased the power to 100%, and after ~ 10 minutes the amplifier turned off and showed |
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Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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this morning with Manar,
we checked the Alphanov amplifier issue : "The laser has been stopped because its power is too far from the nominal power".
the photodiode voltage measuring the output power has drifted again and then, the estimated output power was wrong, triggering an alarm issue. |
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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Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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We took reading of the beam profile of the amplifier without a lens @ 30 cm from the 2nd wedge for amplification percentages
20-30-40-50-60-70-80-90-100 % another additional 3 readings will be taken at different locations for all amplification percentages.
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Power shut down on Saturday the 18th, posted by Ronic Chiche at ThomX igloo about utilities
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All the equipments have been switched off on Friday 17th due to a power shut down on Saturday 18th :
CW and Onefive oscillators, computers, laser amplifier, cavity mirror motors, chiller, etc... |
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33MHz laser SN2439 back to Orsay, posted by Ronic Chiche at Optical room about lasers and optics
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As the general local network for the FP-cavity devices is 192.168.xxx.xxx, I changed the IP adress of the smaract laser motors (Frep and CEP) controller.
For that, I used the embedded web server as described in the manual in attached file.
the new adresses are : |
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Power shut down on Saturday the 18th, posted by Ronic Chiche at ThomX igloo about utilities
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Today, I restarted all the equipements :
Chiller
: ok, temperature converged quickly to the set temperature : 25°C |
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Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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due to several "case temperature" issues, I change the "Max case temperature" in the "general config" of the "Alphanov
Software" from 50°C to 55°C.
=> validated by Alphanov. |
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33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics
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the last tries to lock the 33MHz + amplifier to the 30k Finesse FP-cavity were unsuccessful.
during a laser Frep scan using the Laselock, one observes that the main cavity resonance is not able to stay inside the PZT scan range from one
scan to another (500ms-1s period) |
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33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics
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finding the right modulation/demodulation PDH phase is very difficult on the main resonance because the we get non stationnary signals with a lot of
oscillations.
changing the phase, in this condition, does not really change the error signal. |
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33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics
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today with Daniele, we locked easily (but with a noisy lock) on the secundary resonance and we tried to lock on the main resonance (with very low coupling
~10% which mean a CEP ~Pi)
the lock was possible but was very noisy. |
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33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics
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After removing the 2 generators from the optical table, the lock is much more stable and now, it is possible to lock on the main resonance with a poor
CEP but with quite good stability.
the coupling is still very low ~ 5% for that CEP but if one improves it (CEP ->0), using the laser double-wedge motor, one clearly sees an improvement |
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33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics
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this morning, I tested the laser+amplifier @ 30% lock on the FP cavity with and without Smaract motors.
I recorded the PDH error signal during a lock:
- blue : with Smaract motors controller powered ON but motors are stopped |