Polarization optimization, posted by Loïc Amoudry at Optical room about lasers and optics
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Optimization of the polarization has been made the 03/10/18. Checked in reflection of the cavity in reflection&transmission of a PBS, locked and
unlocked. Only with 2nd stage.
Ratio values are reflection of PBS divided by transmission or the opposite. |
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Record power-up, posted by Loïc Amoudry at Optical room about lasers and optics
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Measurement made on 03/10/18 (nothing has been done since there).
Stable power in the cavity of 225 kW.
3rd stage current
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Motors for D-shaped mirrors, posted by Loïc Amoudry at Optical room about mechanics | lasers and optics 
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Motors have been installed on 16/10/18. No problem with them.
Effect of the motors tested on 17/10/18. No improvement. But they give the possibility to perfectly cut HOM or let them go through as show
the following picture of a 2.2 mode at ~340 mW in trans and 70% coupling @4A. |
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Transmission vs D-shape position at different powe, posted by Loïc Amoudry at Optical room about lasers and optics
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Measurements have been done on 18/10/18.
Datas are on excel file, also matlab file. |
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Beam size vs D-shape position, posted by Loïc Amoudry at Optical room about lasers and optics
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Measurement done on 18/10/18.
At high power, the shape of the 0.0 mode does not change. The D-shape only generate losses in the cavity. Then the power stored in the cavity
decrease. As with this configuration, the cavity beam size decrease when power increase, the beam size decreased. |
Beam size vs D-shape position, posted by Loïc Amoudry at Optical room about lasers and optics
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Matlab code for size vs position and power :
clear all
close all |
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Power measurement with D-shape, posted by Loïc Amoudry at Optical room about mechanics | lasers and optics
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Measurements of lot of points with D-shape mirrors well positionned.
Power not optimized to the best but almost. (@4A could have 350 mW).
I (A)
Ptrans (mW)
Coupling |
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Finesse vs power by difference between main and second resonance, posted by Loïc Amoudry at Optical room about lasers and optics
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Measurements show that ratio decrease versus power. BUT, the second resonance measurement induce lower power in the cavity so the ratio is not directly
true.
Also, simulation of the main/second resonance power by Pierre's simulation has shown ratio ~50, ~47.6 and 43.5 respectively for 0A, 2A and |
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Polarization frequency, posted by Loïc Amoudry at Optical room about lasers and optics
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Check of the frequency of the onefive locked on each polarization of the cavity (tilt a waveplate by 45°).
Frequency repetition rate : 133.335 MHz on spectrum analyzer for both polarization locked. |
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Polarization frequency, posted by Loïc Amoudry at Optical room about lasers and optics
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Measurement on 30/10/18.
Loïc
Amoudry wrote:
Check of the frequency of the onefive locked on each polarization |
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Finesse vs power by difference between main and second resonance, posted by Loïc Amoudry at Optical room about lasers and optics
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Measurement on 24/10/18
Loïc
Amoudry wrote:
Measurements show that ratio decrease versus power. BUT, the second |
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Finesse vs power by difference between main and second resonance, posted by Loïc Amoudry at Optical room about lasers and optics
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Measurement on 25/10/2018
Loïc
Amoudry wrote:
Measurements show that ratio decrease versus power. BUT, the second |
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M1 transmission measurement, posted by Loïc Amoudry at Optical room about lasers and optics
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Center of M1:
I (A)
Input power (mW)
Transmitted
power (mW)
Transmission (ppm)
0
78
0.01477
189
4
16500
3.2
194
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Change of the 3 ULE mirrors by 3 spare ULE mirrors, posted by Loïc Amoudry at Optical room about lasers and optics
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| First finesse measurement 20 266, FSR 133.351 MHz under vacuum |
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M4 transmission measurement, posted by Loïc Amoudry at Optical room about lasers and optics
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The kept transmission for M4 is 2.17 ppm. Which is the value measured after alignement (center of the mirror).
These measurements have been taken before alignement.
I (A)
Input power (mW)
Transmitted |
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M4 transmission measurement, posted by Loïc Amoudry at Optical room about lasers and optics
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Loïc
Amoudry wrote:
The kept transmission for M4 is 2.17 ppm. Which
is the value measured after alignement (center of the mirror). |
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M1 transmission measurement, posted by Loïc Amoudry at Optical room about lasers and optics
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At different positions, transmission give 194, 193, 208, 200 ppm?
Loïc
Amoudry wrote:
Center of M1: |
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First run with spare mirrors, posted by Loïc Amoudry at Optical room about lasers and optics
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I (A)
Trans (mW)
Coupling (%)
Pin
(W)
Gain
0
4
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Mirrors cleaning, posted by Loïc Amoudry at Optical room about lasers and optics
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The new mirrors didn't give expected results. Then the 4 old mirrors have been sent to LMA on 12/11/18 for a cleaning and caracterization before
and after cleaning. Also asked for a diffusion/absorption map on the mirrors if possible. They didn't really answered on what will they do.
Received on 13/11/18 by LMA. |
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Mirrors features, come back from LMA, posted by Loïc Amoudry at Optical room about lasers and optics
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Mirrors arrived today from LMA. Their features are damaged.
Photos avant ou après nettoyage, pas clair dans le mail de Laurent :
"J'ai commencé à nettoyer M1 et M2 avec notr methode habituelle et je me suis aperçu que sur la partie centrale |