Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics 
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I used the 33MHz spectrum measurement : https://elog.lal.in2p3.fr/FPC/THOMX+commissioning/153
fitted by P=P0*sech²((f-f0)/df)
f0 = c/1030m |
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Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics
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Manar + Victor, today in the morning we aligned the CVBG of the stretcher.
The double path using the mirror mounts, reached up to 5.4 mW just before the injection into the fibers
then we rotated the quarter wave plate and the power increased by a factor of ~ 2 to 10.3 mW |
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Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics
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This morning with Manar, we continued the strecher CVBG alignment and fiber injection procedure :
- we checked the power at the output of the laser and confirmed the measurement after the Isolator : ~ 36 mW
- we tried to improve the power after the strecher CVBG by rotating the quarter-wave plate but it seems we were already at the maximum : ~ 10.5 |
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Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics
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this morning : still 6.2 mW at the output of the fiber.
the powermeter has been removed and the fiber connected to amplifier input fiber (no EOM connected in between).
Ronic |
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Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics
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Monday 7/11 morning, the power in the fiber was still 6.2 mW
Ronic
Chiche wrote:
this morning : still 6.2 mW at the output of the fiber. |
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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 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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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). |
Stability test Without and with , posted by Ronic Chiche at ThomX igloo about lasers and optics
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The laser starts at 93 KW.
This morning I operated the laser locked with the RF for 1h30 without any delock. All the machine was switch off.
All the system was very stable. Sometimes the 20 Hz perturbation was visible but no delocking. |
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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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Spherical mirrors at closest position. FSR, finesse and beam size., posted by Loïc Amoudry at Optical room about lasers and optics
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The spherical mirrors are at the closest position to get a FSR ~=33.3435 MHz. Planar mirrors are at the largest position.
The finesse has been measured about 17 000.
Beam diameter (2*w) is ~= 4.6 mm x and y. |
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Smaract motors parameters and controller, posted by Ronic Chiche at ThomX igloo about mechanics | detectors and electronics
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current Smaract motors parameters :
- Closed loop Max frequency : 5000
- Signal Amplitude threshold : 2047 |
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Smaract controller remplacement, posted by Ronic Chiche at ThomX igloo about lasers and optics
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previously, we were using a spare Smaract MCS controller to drive the Onefive linear stages (without -LV -low vibration- option and
using Ethernet),
during the repair of the initial MCS controller with -LV option. |
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Ring frequency / Laser "day by day" locking, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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| today, the equivalent Smaract position corresponding to the 500.25MHz ring frequency is +156µm on MCS-1/ch0 (closed loop mode) |
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Ring frequency / Laser "day by day" locking, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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temperature stable around 20.8°C
today, the equivalent Smaract position corresponding to the 500.25MHz ring frequency is +158.4µm on MCS-1/ch0 (closed loop mode)
it is very difficult to maintain both loops in the same time as soon as it is needed to move one motor (CFP or Laser) because of the one element |
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Ring frequency / Laser "day by day" locking, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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temperature stable around 21.7°C
today, the equivalent Smaract position corresponding to the 500.25MHz ring frequency is +147µm on MCS-1/ch0 (closed loop mode)
Ronic |
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Restarting equipements after Christmas shutdown, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software
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this morning, I plugged back the 4 power cables which supply all the equipments.
all the equipments have restarted without problem, but the shutter of the laser amplifier needs a ThomX safety system grant to let the beam propagate
to the cavity... |
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Restarting equipements after Christmas shutdown, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software
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the laser coupled into the amplifier is still measured at ~3mW at the input, on the Alphanov software, once the Amp stage are started at 0% of power
ratio.
this afternoon, Kevin restarted the 3rd safety system of ThomX to grant the opening of the beam shutter => now the shutter can be opened. |
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Restarting equipements after Christmas shutdown, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software
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this morning, I set the Ring frequency at 500.25MHz and after switching ON the power supply of the amplifiers for the RF signal coming from the laser,
I saw the beating frequency (between ring RF and laser harmonic frerquencies at 500.25MHz) that I canceled, playing with the Smaract motor.
Now, I need to adjust the FP-cavity length to follow the laser cavity length but the IcePap DS (controlling the FP-cavity motor) freezes too |
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Restarting equipements after Christmas shutdown, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software
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on last friday (12/01/2024), the IcePap DS issue was solved and I was able to control the FP-cavity motors properly.
I was able to quickly lock either the laser on the FP-cavity and the FP-cavity on the RF reference as before.
then, we can close these posts on restarting the equipments after the Christmas shutdown |
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Removing high order modes, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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this morning we locked the laser and the FP-cavity with ~ 40kW => some HOM appeared "randomly" depending on the power.
we tried to play manually on the L-shape arm :
- first, we moved horizontally to put the L-shape in the beam axis |