ThomX Locked with CVBGs, posted by Loïc Amoudry at Optical room about lasers and optics 
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ThomX has been locked with a new telescope while using compression CVBGs.
Coupling is ~50-55% and lock is stable.
Power up to ~50kW should follow up soon (stop when HOM are observed). We'll not go over ~100kW to not risk any breakdown due to the |
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Powerup with 2.5ps pulses, posted by Loïc Amoudry at Optical room about lasers and optics
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A power up has been performed on ThomX until 65kW intracavity power. We didn't see any modes but stored power was really unstable since ~60kW (see
image tek00004.png).
Measurement report is shown in the table below. Gain seems to decrease against intracavity power. |
Beam pulse duration, posted by Ronic Chiche at Optical room about lasers and optics
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Last Thursday (20th of February), Loïc and Titouan realigned the stretcher CVBG to its nominal angle and they used an interferometric technique
with a delay line and combining the two paths in a CCD to measure interferences.
After supressing the global shape of the superposed pulses, one measures the amplitude of the remaining fringes (standard deviation) each 50µm |
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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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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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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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Finesse measurement after confinement, posted by Loïc Amoudry at Optical room about lasers and optics
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After 3 months without human presence, finesse has been measured 3 times with average optimization:
- 16150
- 16067 |
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Finesse measurement after the Edge installation, posted by Ronic Chiche at Optical room about lasers and optics
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After the Edge installation inside the cavity, the Finesse has been measured several times by modulation technique with an average around 16000:
(the scan speed is 50kHz in 10 seconds.)
So, it hasn't changed since the last measurement in June, just before the Edge installation. |
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Coating reflectivity, posted by Loïc Amoudry at Optical room about lasers and optics 6x
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| Coatings reflectivity curves and datas for HR Saphir, HR Suprasil and HR ULE. |
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Beam size and finesse, posted by Loïc Amoudry at Optical room about lasers and optics
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Measurement behind P4 (planar mirror)
Loïc
Amoudry wrote:
FSR initiale : 33.34 MHz (S3 = -825000 et S4 = -825000) |
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Onefive ouput power and spectrum, posted by Loïc Amoudry at Optical room about lasers and optics
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After turning on, one can see the 133.33MHz Onefive output power for ~40min with OD2 filter (~/20). So the real output power is ~57mW. A measurment over
several days (15?) should come in few weeks.
The spectrum here has been taken one day after turning on the Onefive (see Fig. 133_spectrum_full and 133_spectrum). One can see the central |
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Onefive ouput power and spectrum, posted by Loïc Amoudry at Optical room about lasers and optics
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1) Note: The OneFive laser used for experimenting is the one for the SBox
but, for now only this laser arrived from the company so we are doing tests (measuring the spectrometer and power ) on it inside the ThomX cavity
clean room. |
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FP cavity alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics
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as the iris used to locate the FP-cavity axis have been removed before moving the table inside the Igloo, we have to find again this FP-cavity axis.
this morning with Viktor, we started to make the alignment of the FP-cavity with a red laser using only the "input window" iris mount
built by Yann. |
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FP cavity alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics
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This afternoon, we continued the alignment of the red laser.
we did it using the 2 final injection mirrors.
we still see a clear transmission after M2, a weak transmission after M3, and almost nothing after M4 due to the power loss going through the dielectric |
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FP cavity alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics
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A continuation of the alignment process was done, there was change in it due to variation in temperature,
it was done using the semiconducting laser, and we were able to obtain an output at M2.
2 references were placed before the alignment mirrors Ma and Mb , to fix the line when changing from semiconducting laser to CW "koheras" |
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FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics
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Note the direction of injection is M1 - M2 - M3 - M4
P1 - S2 - S3 - P4 |
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FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics
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The alignment is on hold until next week 17th - 18th Jan
an Alignment attempt will be done when the ring part close to the FP cavity is opened.
Manar |
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Alignment procedure, posted by Ronic Chiche at Optical room about mechanics | lasers and optics
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Picture of the installed mirrors inside the FP cavity.
To install an Iris instead of a mirror :
One has to remove manually the orange nuts and replace the mirror mount with the Iris mount. |
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Documentation about mechanics on Atrium, posted by Ronic Chiche at ThomX igloo about mechanics
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https://atrium.in2p3.fr/0dded51a-1cb0-43e6-ae0d-626cd5db7078
a lot of schematics regarding the FP cavity are stored by the mechanic group on the Atrium repository. |