Finesse measurement, posted by Alice Renaux at Optical room about lasers and optics 
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Today, with Ronic, we measured the finesse of the 2-mirror cavity witht the NKT CW laser.
We were able to perfrom the measurement only once, and the results of the measurement are attached to this note. We added sidebands to the laser
spectrum peak thanks to an EOM, and we sweeped the modulation frequency on a 1MHz span around an estimated FSR of 216.63MHz in 10s. We found a 82kHz linewidth, |
Finesse measurement, posted by Alice Renaux at Optical room about lasers and optics
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(Finesse 2651 is consistent with that obtained from the mirrors' transmission coefficients, which is about 3100.)
Alice
Renaux wrote:
Today, with Ronic, we measured the finesse of the 2-mirror cavity |
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new cavity, posted by Alice Renaux at Optical room about lasers and optics
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Yesterday, we changed the M1 mirror to a 161185 Gamma Factory mirror of transmission 460ppm, the cavity
finesse is now 13360.
We managed to lock it today. |
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new cavity, posted by Alice Renaux at Optical room about lasers and optics
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The 2-mirrors cavity has 460ppm of transmission for M1 and 10ppm for M2 which should exhibit a Finesse around 13400.
Today, we managed to lock the NKT laser (with an AOM for fast feedback) onto the cavity, and we made 5 Finesse measurements with the modulation
technic : 14151, 13847, 13968, 14604, 13892 with an average around 14000 => LW = 216MHz/F ~ 16kHz. |
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Neolase amplifier installation, posted by Ronic Chiche at Optical room about mechanics | lasers and optics | cabling
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we have all the adaptor plugs for connecting the chiller.
so, I tested first the chiller connected in closed loop (on itself).
there is no manual, so procedure is not completely clear... |
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Neolase amplifier installation, posted by Ronic Chiche at Optical room about mechanics | lasers and optics | cabling
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now, I connected the chiller circuit to the amplifier, thanks to the adapters.
chiller IN => blue pipe => laser OUT
chiller OUT => black pipe => laser IN |
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Neolase amplifier installation, posted by Ronic Chiche at Optical room about mechanics | lasers and optics | cabling
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pipes are maybe too long ?
we can use the Darcy-Weisbach + Blasius laws (non linear laws).
I asked to ChatGPT, Claude, Mistral and MathGPT to solve it with these parameters : |
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Neolase amplifier installation, posted by Ronic Chiche at Optical room about mechanics | lasers and optics | cabling
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I drained the chiller to install again the short pipe (< 1m) in closed loop.
then, I filled again the chiller and did the compression process to obtain 1bar.
in that case, the flow measured by the chiller is correct about 5.8Lpm. |
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Neolase amplifier installation, posted by Ronic Chiche at Optical room about mechanics | lasers and optics | cabling
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now, I installed the long pipes (2x 3m) in closed loop (without the amplifier connected), but the exact ones used to connect the laser, with the same
pipe adapters.
after the compression process, the chiller works at 0.9 bar and the measured flow is 4.7Lpm. |
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Neolase amplifier installation, posted by Ronic Chiche at Optical room about mechanics | lasers and optics | cabling
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I cut a small part of the black pipe on the amplifier side (could it be slightly deformed by a try with an other type of adapter ?), with the dedicated
tool, changed the adapter and plugged it more firmly in the pipe (pipe deeply inserted in the adapter).
it seems, there is no more leakage. |
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Neolase amplifier installation, posted by Ronic Chiche at Optical room about mechanics | lasers and optics | cabling
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as soon as I connect the amplifier to the pipes, the flow decreases to 1.7Lpm.
and the filling process is very long and noisy, as there was something blocking the filling process... |