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 ! |
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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Transmission Measurements for the Mirrors. , posted by Manar Amer at Optical room about lasers and optics 6x
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Thursday 10 December 2020: First Test Measurement - Inside Box
The transmission ( T ) for the mirrors of SBOX
and ThomX was measured over a range from the center of the mirror up to 5mm.
The first setup was initially done while the
mirrorr is installed inside the metal box, when measuring T we observe that there is an erregular change in the power measured as we move azay from |
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Telescope / amplifier output, posted by Manar Amer at Optical room about lasers and optics
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The previous Sbox telescope was dismantled and the mechanical components cleaned.
its lenses are still in the mounts, it looks that two of them are spherical and two are cylindrical
2 are -100 mm and 2 are +150 mm, there is also a box containing fused silica lenses that could be used. |
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Telescope / amplifier output, posted by Manar Amer at Optical room about lasers and optics
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Beam divergence was measured using a method called "Focal
Length Divergence
Measurement Method" |
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Telescope / amplifier output, posted by Manar Amer at Optical room about lasers and optics
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I placed a periscope to adjust the high of the beam from the amplifier output from ~ 10 cm from the table to ~ 15 cm
a dichroic mirror placed after it to reject the pump laser, all the mirrors on the path to the cavity were replaced with dielectric mirrors BB01-E03
the length of the path from the amplifier output to the cavity coupling mirror ~ 2 meters |
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Telescope / amplifier output, posted by Manar Amer at Optical room about lasers and optics
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Here is a view of beam propagation in the optical software : GaussianBeam
the red filled shape is the model of the CELIA amplifier beam propagation with a divergence of 4.46 mrad
(the 2 black dots is the measurement of the beam size without any lens to change the beam propagation). |
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Telescope / amplifier output, posted by Manar Amer at Optical room about lasers and optics
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removing the reading which is not correct (wrong use of software)
redone a reading similar using a lens of focal 250 mm got a FWHM-X = 0.64 mm , FWHM-Y = 0.84 mm
using the vertical to calculate the divergence, we get divergence ~ 2.17 mrad which is closer to fit obtained for the beam profile by taking |
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Telescope / amplifier output, posted by Manar Amer at Optical room about lasers and optics
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Note the correct beam divergence is approximately ~ 2.3 mrad
M2 = 1.1 in this fit, but it is not yet optimized !!!!! could be reason for not accurate telescope
reading. |
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Telescope / amplifier output, posted by Manar Amer at Optical room about lasers and optics
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Am adjustment on the lenses position to have a smaller waist.
+ 250 mm @ 88 cm from amplifier
-150 mm @ 111 cm from amplifier |
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Telescope / amplifier output, posted by Manar Amer at Optical room about lasers and optics
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We increased the power of the amplifier up to 10 W to see if there is a change in the beam shape at the injection point or the transmission.
There was no change in the shape of both of them from the reading at 1 W (with only the 2nd stage on)
Only saw an increase in the transmission power, which is expected. |
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Telescope - Spacial Matching , posted by Manar Amer at Optical room about lasers and optics
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Divergence of the CW beam out of the collimator measured after 1 meter to be
2 x = 0.7425 mrad --> x = 0.37125 mrad
2 |
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Successful lock (finally !), posted by Alice Renaux at Optical room about lasers and optics
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Today, with Ronic, we managed to get a successful lock with the NKT laser by setting up a new PDH box from scratch (photodiode + amplifer + mixer).
Me measured the injected power (5.4mW) and the transmitted power (33µW) after a wedge (92% transmission) and a 7ppm transmission mirror,
so the intracavity power was 5.1W. We have a 950 enhancement factor for a 3100 finesse cavity, so a nominal enhancement factor of 2500. The lock was very |
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Spincoater - Mirrror cleaning , posted by Manar Amer at Optical room about utilities
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In preparation for cleaning the mirrors.
The spincoater has been moved with its bump into the sas of the SBox.
The pure water used will be provided by Alice, as the previous source in the workshop is not available. |
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Spincoater - Mirrror cleaning , posted by Manar Amer at Optical room about lasers and optics | utilities
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Used the spincoater and pure water to clean dielectric mirrors which will be installed inside the SBox for directing the reflection line.
The method : place pure alchole on mirror - wipe it using white sterile tissue (in one direction) - clean with pure water in spincoater suing
cotton swap . |
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Spincoater - Mirrror cleaning , posted by Manar Amer at Optical room about lasers and optics | utilities
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Images of the SBox mirrors cleaned at the same time when the cavity was aligned.
Directly from the spincoater to the SBox directly.
PowerPoint attached shows details |
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Spincoater - Mirrror cleaning , posted by Manar Amer at Optical room about lasers and optics | utilities
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PowerPoint shows the detailed images of all the mirrors before and after cleaning.
Images of SBox mirrors and M1 from Gamma factory attached only for the front after cleaning
the lines showing are on the back of the mirrors, they come from the spinning mount the mirrors are fixed on in the spin-coater. |
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Spincoater - Mirrror cleaning , posted by Manar Amer at Optical room about lasers and optics | utilities
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Following the observation that when rotating M2 plan mirror of SBox the deformation position of the mode changes.
M2 was replaced with M2 spare of SBox
images of the mirror front side attached before and after cleaning, no spots at the center, but there seems to be 2 spots far from the center |
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Spincoater - Mirrror cleaning , posted by Manar Amer at Optical room about lasers and optics | utilities
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While repeating the alignment, the mirrors were cleaned using the spin-coater and placed again.
The current mirrors placed in the SBox are
M1 plane injection from Gamma factory |
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SBox Finesse at 216.6625 MHz, posted by Manar Amer at Optical room about lasers and optics | vacuum
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The Sbox currently has the injection from ThomX installed T ~ 120 ppm , M2 planar from Sbox spare and M3 / M4 spherical mirrors from Sbox installed.
The last finesse measurement that was done gave a Finesse of ~ 19300 (After cleaning M2 using ethanol + aceton + pure water)
on Friday the whole optical table was cleaned again and the inside of the box was cleaned (even with a lot of dust inside the box the Finesse |