screws for the ring fixing the mirrors , posted by Manar Amer at Optical room about mechanics
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On Friday, when placing the mirror in the mount inside the cavity, the mirror is fixed using a ring with 3 screws
one of the screws fell through the holes connecting the breadboard to the box (managed to remove it, but there was a lot of dust and metal particles
left after) |
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report on dead EOMs, posted by Aurélien Martens at Optical room about detectors and electronics
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I tested the status of several EOMs by injecting them with the CW OEWaves laser. Its power is of 15.37mW.
With the viewer one can see where losses are located. For 3 of them, there is no power at output (nW).
for S/N 11419-12 and 10305-09 some losses are visible at the splicing point (IN side) of the EOM metallic case. |
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first entry in logbook, posted by Ronic Chiche at Optical room about utilities
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| first entry in logbook |
Replacing prefilters for filter unit, posted by Manar Amer at Optical room about utilities 
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The 5 prefilters for the SBox have been changed and at the same time a cleaning of the visible part of the motor was done using tissue and alcohol.
For a start they were cleaned using Vacuum cleaner , to be cleaned later using water
A timetable was placed with the date of the change and the next expected one. |
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Optical closet content, posted by Loïc Amoudry at Optical room about mechanics | lasers and optics | utilities
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Electronic:
EOM photoline NIR-MPX-LN-10, S/N: 2559-22 x1
EOM newfocus free space 5 MHz IR, model H063-M x1 |
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OneFive laser installation, posted by Ronic Chiche at Optical room about mechanics | lasers and optics
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SBOX table cleaned and Origami 133MHz laser installed.
power measurement with powermeter and AA-OD1 filter (factor 10 of attenuation) = 3.88 mW |
Laser isolator, posted by Ronic Chiche at Optical room about mechanics | lasers and optics
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No optical isolator available.
One used a half waveplate, a PBS, a faraday rotator and a PBS on a rotating mount to build an optical isolator.
the global transmission measured with powermeter equiped with AA-OD1 filter is 3.68 mW |
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Fiber injection and amplifier diagnostics, posted by Ronic Chiche at Optical room about lasers and optics
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Today with Titouan, we installed a 10-90% fiber coupler between the EOM and the amplifier to have a diagnostic of the fiber injection power level.
65mV on 1kohms on the diagnostic photodiode is equivalent to 1.3mW injected to the 1st stage of the amplifier.
One has to get at least 50mV on the photodiode to inject 1mW to the 1st stage of the amplifier. |
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Fiber injection and amplifier diagnostics, posted by Ronic Chiche at Optical room about lasers and optics
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The fiber connected to the 2nd stage photodiode was broken.
Thus, one connected the Auxilary output which is placed on the front cover, coming from a 10% tap of the 2nd stage, with a fiber to this photodiode.
for that, one drilled a small hole on the side to the crate to let the fiber in. |
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Fiber injection and amplifier diagnostics, posted by Ronic Chiche at Optical room about lasers and optics
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this morning, the photodiode from the fiber coupling was only at 17mV (it was 40mV before the Christmas holidays).
after global realignment (infjection and CVBG !) we are back to 40mV which corresponds to 0.83mW into the 1st stage of the amplifier.
one added a photodiode (with one ND) after the OneFive, using a parasitic reflexion of the 1st PBS (the one used to work as an isolator), to |
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Fiber injection, posted by Ronic Chiche at Optical room about lasers and optics
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The power reflected by the CVBG after the PBS is measured at 8.16mW (powermeter without AA-OD1 filter)
The power injected in a unpolarized fiber is about 5.4mW
The power injected in the EOM fiber (to be directly connected to the amplifier) is 1.5mW (1.72mW if a lambda/2 is added and 1.76mW if both lambda/2 |
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Chilller installation, posted by Ronic Chiche at Optical room about mechanics
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Yesterday, we installled again the chillers for the 2nd and 3rd stages of the 50W laser amplifier.
We changed the 2nd stage chiller tube connections by a press-fit connection which is almost leakage-free and much more convenient.
We shortened also the tubes and set the temperature to 19°C. |
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Cavity Box Under Vacuum , posted by Manar Amer at Optical room about vacuum
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Yesterday evening, we closed Cavity Box and placed it under the primary pump for ~2 hours. then for lack of time we switched it off (did not want to
leave it overnight as it could heat up).
After closing the valve connecting the pump with the cavity and switching the pump off, a slight increase in pressure happened and then a very |
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CVBG laser spectrum, posted by Ronic Chiche at Optical room about mechanics | lasers and optics
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Frep et CEP motors action has no effect on the spectrum central wavelength.
See the plot of the total OneFive spectrum (in black) and the part reflected by the CVBG (in red)
only 9.38% is reflected. |
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CVBG and laser spectrum, posted by Ronic Chiche at Optical room about mechanics | lasers and optics
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CVBG has been installed but reflected power is much lower than before (new power in black with OD1 filter, old power in red... see attached fiber injection
scheme)
it seems the OneFive spectrum shifted a lot with 40mW of output power. the center wavelength is roughly 1028.5 nm, thus the CVBG reflection is |
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200kW & 160kW 30min run, posted by Huan Wang at Optical room about lasers and optics
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the attched image is the plot of the datas from two high power experiments,
- the blue curve is from the high power experiment on 12/09/2018, injecting laser power is 27W, power inside cavity dropped from 157kW to 138kW |