Cameras Calibration, posted by Kevin Dupraz at Optical room about lasers and optics | detectors and electronics 
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Kevin
Dupraz wrote:
After installing cameras the actual calibration are : |
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Cameras Calibration, posted by Kevin Dupraz at Optical room about lasers and optics | detectors and electronics
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After check a mistake has been found on the magnification. This seems to be the good calibration (feel free to cross check). The projection of the 2mm
hex is attached
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Manip 10 12 2021 (optimization injection Burst), posted by Kevin Dupraz at Optical room about lasers and optics
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Manip 10/12/2021
Après recherche de la résonnance principale
- MCS miroirs plan à 5.110250mm (en derive vers les negatifs) |
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Manip 14 12 2021 injection optimization (and calibration), posted by Kevin Dupraz at Optical room about lasers and optics
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Matin :
moteurs :
M1, M2 (plans): 5.110500m |
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Manip 14 12 2021 injection optimization (and calibration), posted by Kevin Dupraz at Optical room about lasers and optics
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Après-midi :
* Optimisation de l'alignement en injection pour avoir le plus de puissance en transmission
* Optimisation (vérification) de la polarisation pour avoir le plus de couplage. |
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Manip 16 12 2021 montée en puissance, posted by Kevin Dupraz at Optical room about lasers and optics
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Matin:
* Redémarrage Tangor 4W
- couplage 15% |
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Manip 16 12 2021 montée en puissance, posted by Kevin Dupraz at Optical room about lasers and optics
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Kevin
Dupraz wrote:
Matin: |
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Manip 17 12 2021 reprise réf nouvelle injection pour polarisation, posted by Kevin Dupraz at Optical room about lasers and optics
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Tangor : 4.2W
* Réalignement de l'injection suite aux modifications :
- Changement de l'ordre des waveplate maintenant : lambda/4, puis lambda/2 |
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Polarisation Results of the NKT, posted by Blanc at Optical room about lasers and optics
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I made many tests about polarization and we can see some points thanks to the following figures :
1- The ellipsicity of the NKT is near to 0 (between -0,2 and 0,2) which means the polarization is rectilinear horizontale (attachement 1).
2- The power of the NKT has no influence on the polarization, verticale or horizontale (attachement 2 and 3). |
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Locking of the cavity and setup changing, posted by Blanc at Optical room about lasers and optics | detectors and electronics
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We change the setup a bit to have the same polarization on the photodiode and the PDH (in reflexion of the cavity). CF: schematics (futur).
Thanks to that, the symetry between reflexion and transmission is better now (as you can see on the plot).
We also put more power on PHD to have a better SNR by changing splitters. (We had 100 µW and now we have more than 1 mW, at the expense |
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Polarisation Results of the NKT, posted by Blanc at Optical room about lasers and optics
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To have the polarisation, we must have 1 value because the laser in entry of the system has 1 polar. Due to that, the graphe of the ellipticity is not
true, it is the mean value on the following table which shows the ellipticity and the polarization.
Blanc |
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Ring light in the cavity, posted by Blanc at Optical room about lasers and optics
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We put a diaphragm in the input beam but it doesn't work to suppress the ring light only but it attenuates the whole transmitted beam (cavity mode
and ring light) viewed on the camera. |
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Polarization Results in transmission, posted by Blanc at Optical room about lasers and optics
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After data processing, I finally find the polarization in transmissin of the FPC. As you can see below, the polarisation is not linear but elliptical.
The four ellipsies are here due to having not enougth parameters to extract with certainty one ellipse. |
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1GHz oscillator Frep measurement, posted by Blanc at Optical room about mechanics | lasers and optics | detectors and electronics
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a previous cavity FSR measurement was giving a center frequency around 867.5MHz.
the present 1GHz oscillator Frep measurement is about 879.888MHz.
the
present shift is about 12.4MHz which is equivalent to move one cavity lenght by 4.3mm which is HUGE !!!
as the 1GHz oscillator does not have any motor,
one has to move the FP cavity mirrors instead.
the PZT inside the 1GHz oscillator (Thorlabs PC4QR) has a dynamic range of (20µm for 150V... we will |
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Finess and coupling measurement, posted by Blanc at Optical room about lasers and optics | detectors and electronics
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We did the measurement of the Finess and coupling with the NKT, with 2 EOM, without AOM (so the lock signal is noisy), on the burst line.
For the coupling, we have the same value as with the GHz locked on the burst line too, which is around 20 percent.
it seems this low coupling comes from the geometrical coupling as we observed an incoming beam bigger than the cavity mode on the cameras. |
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Setup and measurements, posted by Blanc at Optical room about lasers and optics | detectors and electronics
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To summerize the results of this week :
We made the setup in attachement 5 and align it to have the good mode in the cavity (TEM00).
With the good alignment, we found the lock of the GHz, in attachement 1. We used the motors in the cavity to position very precisely the mirrors |
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1GHz oscillator Frep measurement, posted by Blanc at Optical room about mechanics | lasers and optics | detectors and electronics
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The optical spectrum of the GHz oscillator: FWHM ~ 4nm
Blanc
wrote:
a previous cavity FSR measurement was giving a center frequency around 867.5MHz. |
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Presentations, posted by Blanc at Other about utilities
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| Here the first part of all the presentations since the beginning of the project. |
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Presentations, posted by Blanc at Other about utilities
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| Here the second part of all the presentations since the beginning of the project. |
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Presentations, posted by Blanc at Other about utilities
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| Here the last part of all the presentations since the beginning of the project. |