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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Mightylaser Amplifier , posted by Manar Amer at Optical room about lasers and optics | cabling
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Migthylaser amplifier has been moved from the SBox table to the PLIC table.
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Microscope and cleaning of SBOX mirrors, posted by Loïc Amoudry at Optical room about lasers and optics
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The mirrors went in the cavity the 28th of november (We did several power up to 30kW stored and only one to 40kW then the power went down to 2kW
during the run).
Microscope study shows that mirrors get some dust during the handling [travel from microscope to SBOX --> installation --> |
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Menhir pulsed laser locking, posted by Xinyi Lu at Optical room about lasers and optics
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These days, Ronic, Daniele and I achieved stable cavity locking with the menhir pulsed laser.
- After vacuuming, the current cavity finesse is now about 23,000. The diameter of the cavity mode is w_x=2.2mm, w_y=2.7mm.
- We had to compensate for frequency drift by manually adjusting the cavity length to keep locking. |
Menhir pulsed laser locking, posted by Xinyi Lu at Optical room about lasers and optics
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Here is a simulation of the relative FP-cavity gain vs the CEP for a Finesse of 23000 and taking into account the Menhir laser optical spectrum and several
CVBG parameters.
I added the commented Matlab code to produce this plot. |
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Menhir pulsed laser locking, posted by Xinyi Lu at Optical room about lasers and optics
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Last week, Ronic and I focused on CEP measurements of the menhir laser.
Measurements without Cavity Locking:
Direct measurement of repetition rate (Frep) with a spectrum analyzer.
Altering the laser pump current from 950mA to 850mA, Frep changed by +28Hz.
Measurement of the variation of carrier-envelope frequency |
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Menhir pulsed laser locking, posted by Xinyi Lu at Optical room about lasers and optics
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here is the code to get this last curve
Xinyi
Lu wrote:
Last week, Ronic and I focused on CEP measurements of |
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Menhir Pulsed Laser, posted by Manar Amer at Optical room about mechanics | lasers and optics | detectors and electronics
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The SBox Length (FSR), was changed to match the repetition rate of the Menhir pulsed laser Frep = 216.6625 MHz
It was changed by removing the 2 D-shaped mirrors placed between M1 and M2, distance between M1-M2 ~= 169 mm
it was still needed to be adjusted with M1 motor to reach the correct FSR. |
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Menhir 216MHz laser, posted by Alice Renaux at Optical room about lasers and optics
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The Menhir 216MHz laser has been put back in place on the cavity table. Its output power is measured to be 160mW with an attenuator. Its spectrum is
available in "spectre.xlsx" and "spectre.png". The main wavelength is a bit shorter (1028.75nm) and the spectrum a bit narrower (4.73nm)
than expected. |
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Menhir 160MHz laser, posted by Alice Renaux at Optical room about lasers and optics
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The Menhir 160MHz has been put back in place on the CELIA amplifier setup. Its output power is measured to be 150-160mW with an attenuator as expected.
Its spectrum is available in "spectre_avant_cvbg.xlsx" and "spectre_avant_cvbg.png".
The pulses are stretched by means of a CVBG. Their spectrum is available in "spectre_apres_cvbg.xlsx" and "spectre_apres_cvbg.png". |
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Meeting with LMA people, AFM, posted by Loïc Amoudry at Other about lasers and optics
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30/01/19 - The following powerpoint shows the results discussed with LMA people.
What came out from the discussion is:
- Their cleaning method uses demineralized water drop on a spinner. It is probably the explanation of the circular traces on the mirror's |
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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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M2 ThomX spherical Cleaning , posted by Manar Amer at Optical room about lasers and optics 6x
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Today, M2 Spherical-3 from ThomX that was installed inside the SBox was removed, there was one big dust on the surface of the mirror, mirror was cleaned
using pure ethanol and pure water with spincoater. (images taken with arrow far from us)
M1 from Gamma factory, fixed with the addition of the ring with 3 screws. |
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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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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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M1 ThomX used while shifted from damaged spot , posted by Manar Amer at Optical room about lasers and optics
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Yesterday , we locked the cavity and we see a sign of a high finesse on the transmission signal, but no measurement of Finesse was done.
we have a coupling of ~ 45%, which is a loss of 20% from the previous coupling of 60%
an estimate done by Ronic MATLAB simulation for the coupling drop where we have 200 pp additional losses and gain of 2.6 k we should get a transmission |
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M1 ThomX used while shifted from damaged spot , posted by Manar Amer at Optical room about lasers and optics
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To compare between the 2 images of the cavity mode:
the mode by itself has an integration time of 0.06 ms, position (x, y) = (1142.969, -53.932) um on the beam profiler
the
mode saturated with the spot next to it almost at max intensity has an integration time of 50 ms, position (-3700, -2000) um
comparing |
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M1 ThomX used while shifted from damaged spot , posted by Manar Amer at Optical room about lasers and optics
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On Wednesday 21st , I opened the cavity did an additional 2 mm shift of the injection mirror and put it under vacuum again.
Locked the cavity, and observed the transmitted beam.
The second spot is still visible on the beam profiler , the distance difference between the 2 spots is ~ 5.2 mm (the same as before ) |
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M1 Gamma Factory, posted by Manar Amer at Optical room about lasers and optics
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In the morning, Vacuum broken and rotated M1 ThomX 90 degrees clockwise, locked the cavity in air and we observe a degeneracy close to the fundamental
mode.
In the afternoon, I cleaned M1 from Gamma factory using pure ethanol and pure water with the spincoater |