Pointing stability with CVBG, posted by Ronic Chiche at Optical room about lasers and optics 
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Yesterday, with Titouan, we made some measurements on pointing stability of the laser beam after amplifier and CVBG.
the amplifier beam go through a first telescope to be small enough and colimated before going to CVBG's, then go to CVBG's and then is sent
through the FP-cavity telescope to the FP-cavity itself. |
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Pneumatic valves, posted by Loïc Amoudry at Optical room about mechanics
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| Frederic and Manu from vacuum group came this morning to fix again the pneumatic valves which had a leak again. |
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Pneumatic valves, posted by Loïc Amoudry at Optical room about vacuum
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The pneumatic valves are now plugged on the university air network.
The air valve is fully openned for the moment.
We still have to check if there is some minor leakage close to the pneumatic valve to improve the setup. |
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PW laser Injection into cavity , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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Yesterday,
we installed the second high power reflecting mirrors at the output of the amplifier.
We aligned and installed a telescope
that has adjustable distance between the 2 lenses of -100 mm, and + 200 mm, with approximate diameter at the injection window of ~ 4.5 mm.
Amplifier |
PW laser Injection into cavity , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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On Monday with Daniele,
we did full characterization of amplifier beam @ 10% amplification, adjusted the telescope accordingly
and injected into the cavity aligned and improved on the fundamental mode.
On Tuesday with Daniele and Kevin
I
added a low pass filter between 1 - 1.9 MHz on the reflected signal, to reject the oscillator signal (33.33 MHz)
removed the external resistors |
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PW laser Injection into cavity , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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Added Note: the coupling we get is at low power, only preamplifier is on (~ 300 mW)
was done at the end due to excitation of higher order modes.
Wanted to improve the fundamental first, then increase the power. |
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PW laser Injection into cavity , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics
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Today with Ronic and Daniele we attempted to lock the cavity, but the alphanov amplifier did not turn on because of an error in MMD3 (related to the
third stage)
the new error is having the MMD3 error show on the alarm window of the LAL software, and having the Alarms on the line 3 of the alphanov software |
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P4 cleaned and finesse measurement, posted by Loïc Amoudry at Optical room about lasers and optics
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P4 cleaned with isopropanol.
Finesse measured afterward: ~=13 000 (clear increase) |
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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here are the (good) lock parameters used this morning.
for the RF/FPC lock, the 33MHz beating signal used to select the right bucket is 1Vpp
=> beating signal : V0 . sin(phi) with V0=0.5V. |
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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Today with Daniele and Alice, we operated to cavity.
we obtained 84kW for 33% of amplifier ratio.
we had to tune the CEP @ -565µm and the FP-cavity alignment. |
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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This morning, I wanted to test quickly if the Smaract motors can be used in open loop instead of closed loop or in piezo scan.
the goal is to do very fine steps without to much vibrations (like with piezo scan mode) but with the full motor range (the piezo scan mode
has a very limited range). |
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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This afternoon, we scanned the optical table vertically with the hexapod in asynchronous mode to find its optimum position, looking at the X-ray production.
then, we searched for the correct bucket and phase in the bucket thanks to the Kevin script on the 500MHz and the 33MHz phases.
we got relatively easily some stable X-rays. |
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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Today, after setting the locking parameters, I got 80kW in the FPC for 33% amplifier ratio after CEP tuning (Smaract CH2 ~ -423.5µm) and alignment.
maybe the alignment has to be improved by some walking procedure.
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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this morning, I did some walking procedure and I got 82kW in the FPC with 33% amplifier ratio (after CEP optimization too).
but when I move the FP cavity motors to adjust the frequency, I cannot keep this power and it is reduced.
could it be we get a stronger correlation between axis than before in the mechanics has more rust than before ? |
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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this morning, I did some walking procedure and CEP alignment to get ~80kW in the FPC with 33% amplifier ratio.
we have to check if this power drop comes from:
- a laser amplifier power drop |
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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the RF frequency is now 500.1003MHz which is equivalent (if divided by 15) to 33.34002MHz.
the frequency has to be changed by ~2kHz @33MHz <=> ~550µm /2 for one motor.
I changed the laser and the FP cavities frequency. |
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Optical spectrum before and after CVBG, posted by Ronic Chiche at Optical room about lasers and optics
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Measurement of the optical spectrum with Avantes OSA before (1st picture) and after CVBG (2nd picture) with 2nd stage on the laser amplifier.
The 1st CVBG stretches the beam horizontally due to the default incident angle and the fact that different wavelength are reflected in the CVBG
with different depth. |
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Optical spectrum analyzer resolution, posted by Ronic Chiche at Optical room about lasers and optics
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The Koheras @0.5mW is directly connected with fibers FC/APC -> FC/PC to the Avantes optical spectrum analyzer.
The FWHM wavelength, measured with the Avantes software, is 0.126nm |
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Optical spectrum analyzer resolution, posted by Ronic Chiche at Optical room about lasers and optics
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Same measurement with Koheras @100mW and using fiber coupling lenses between Koheras and Avantes OSA.
The FWHM wavelength, measured with the Avantes software, is 0.116nm
Ronic |
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Onefive spectrum and CVBG spectrum, posted by Loïc Amoudry at Optical room about lasers and optics
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| The Onefive spectrum has shifted a little bit to lower lambda. It's still enough for the experiment (3mW injection of ampli intead of 1mW needed). |