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 |
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 |
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Deposit on S-box mirrors after return from LMA, posted by Loïc Amoudry at Optical room about lasers and optics
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| Cleaning on dirty surface shows something is deposited on the surface. Cleaning displaces and removes part of the deposit. |
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Impacts on mirror's surface, posted by Loïc Amoudry at Optical room about lasers and optics
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All the mirrors show impacts on there surface (some of them do not show deposit). Does it come from experiments or fabrication ? Are these holes
or bumps ? |
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amplifier, posted by Huan Wang at Optical room about lasers and optics
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Onefive output power is 24mW now, and 2.41mW(after EOM) injected into fiber,
a injection power monitor added, 99% (2.06mW) injected into amplifier, 1% (16.1uW) monitored with photodiode DET36A/M, which
gives ~500mV DC signal on oscilloscope with 1Mohm impedanc; |
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amplifier, posted by Huan Wang at Optical room about lasers and optics
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I just had a phone call with Jérome and he told me 2 things :
* Be carefull ! the MightyLaser amplifier is not designed to work with 33MHz laser : the streching level is not sufficient !
One could worsen the phase noise by self-modulation due to peak power or even distroy the amplifier ! |
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Mirror's cleaning, posted by Loïc Amoudry at Optical room about lasers and optics
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XPS has been proceeded on the 400kW SBOX mirrors M3 and M4 (the initial cavity spherical mirrors) in frebruary 2019. Deposited a lot of particles on
these mirrors.
All the mirrors received a Infrared spectroscopy the 12th of november 2019. Deposited glue on the non-reflective face (was used to hold them). |
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Mirror's installed, posted by Loïc Amoudry at Optical room about lasers and optics
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| The initial 400kW SBOX mirrors which have been cleaned ont 28th of november have been installed this morning on the SBOX. |
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FSR and Finesse measurement, posted by Ronic Chiche at Optical room about lasers and optics
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Yesterday the cavity has been aligned and locked with the CW Koheras laser.
the FSR has been measured by modulation technique at 133.344MHz at 1mbar pressure in the cavity.
the polarization has to be optimized for the Finesse measurement otherwise, some "shoulders" appear beside the Airy peak and reduce |
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2nd stage amplifier issue, posted by Ronic Chiche at Optical room about lasers and optics
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the 2nd stage amplifier needed several hours (4-5h) to reach its nominal power (we look at photodiode level on a scope), instead of the awaited 30 minutes.
could it come from the probable spectrum shifting of the OneFive laser ?
(the power coming from the CVBG, coupled to the fiber, is lower than expected). |
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2nd stage amplifier issue, posted by Ronic Chiche at Optical room about lasers and optics
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Last time, we switched ON directly the 2nd stage at 6A without increasing/decrinsing slowly the current.
today, we switched ON the chiller, switched ON the 1st stage, switch ON the power supply of the 2nd stage at 0A and then we increased slowly the
current until 6A... and the problem disappeared. |
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2nd stage amplifier issue, posted by Ronic Chiche at Optical room about lasers and optics
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2nd stage output power was going down. We checked the pump diode technical data sheet and the operating temperature is [25°C:35°C].
We increased the chiller temperature setpoint from 19°C to 23°C.
Then the output power increased (93mW on 2nd stage photodiode). |
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first data with 3A on the 3rd stage, posted by Ronic Chiche at Optical room about lasers and optics
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Today, at 3A on the 3rd stage, we saw some HOM effects.
the transmissions is about 100mW which corresponds to 30kW inside cavity.
we tried to play with D shape motors but without success. |
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Beam size behind M2, posted by Ronic Chiche at Optical room about lasers and optics
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Beam diameter behind M2 :
- 2nd stage @ 6A - 1kW inside cavity
sx = 2120 µm |