Alignment procedure, posted by Ronic Chiche at Optical room about mechanics | lasers and optics
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we did again the complete alignment procedure starting with iris and optimizing injection motors Ma and Mb, then installing mirror S2, S3, P4 and P1,
optimizing thetaX and thetaY axis for each motor.
everything was fine until we installed P1. we tried to optimize thetaX and thetaY of P1 and we clearly observed a strange motion when doing that |
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Finesse after removing wires, posted by Loïc Amoudry at Optical room about lasers and optics
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19/04/01: We removed the wires from the beam path in the cavity. Finesse stayed at 3400. FSR: 33.342 MHz.
When locked:
Input Power: ~4mW |
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Transmission of the mirrors, posted by Loïc Amoudry at Optical room about lasers and optics
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We openned the cavity, removed S2 and measured trans of P1 and same for S2.
Pin ~= 3.91 mW
PS2 ~= 20 nW --> ~~ 5 ppm !!! |
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Beam size at closest spherical mirrors position, posted by Loïc Amoudry at Optical room about lasers and optics
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S3 and S2 @ +1 640 000 and P1 and P4 @ -825 000
Diameter in x: 4.7mm
Diameter in y: 4.7mm |
Transmission of the mirrors, posted by Loïc Amoudry at Optical room about lasers and optics
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After verification, transmission of P1 correspond to ~150ppm.
The 1337ppm come from a beam leakage. Reflection from P1 goes to the input window which reflects again a part of the beam directly into the cavity
between P1 and S3 then between P4 and S2. |
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Transmission of the mirrors, posted by Loïc Amoudry at Optical room about lasers and optics
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P1 transmission out of the mount (means angle of the mirror is not the real angle):
Pin = 3.2 mW
Pout = 545 nW |
Finesse with P1 SUPRASIL, posted by Loïc Amoudry at Optical room about lasers and optics 
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P1 SUPRASIL has been installed instead of P1 Sapphire. It has been cleaned 3 times on each face with wipe+isopropanol before to be installed.
Finesse ~= 10 000 - 11 000 (EOM Sweep of 100 kHz in 10sec, see last image.)
Coupling ~= 45% |
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Finesse after 2days, posted by Loïc Amoudry at Optical room about lasers and optics
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Finesse measured this morning after P1 SUPRASIL being into the cavity for two days. In order to check if it's getting dirty.
Finesse still ~= 11 000 |
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P4 cleaned and finesse measurement, posted by Loïc Amoudry at Optical room about lasers and optics
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P4 cleaned with isopropanol.
Finesse measured afterward: ~=13 000 (clear increase) |
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Mirror's cleaning and finesse, posted by Loïc Amoudry at Optical room about lasers and optics
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Summary of what have been cleaned the last week:
P1 with isopropanol, finesse 11000
P4 with isopropanol, finesse 13000 |
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Injection of 33MHz Onefive through fiber, posted by Loïc Amoudry at Optical room about lasers and optics
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Output power of the Onefive, and power after injection and different components have been measured.
Coupling ~= 90%
Each of our two EOM roughly have the same loses ~3dB |
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33MHz Onefive power overtime decrease, posted by Loïc Amoudry at Optical room about lasers and optics
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Power of the 33MHz Onfive decreases over time. Have to pay attention to that.
Note that air dryers have never been stopped.
10th april 2018: ~40mW (first picture, 10dB filter) |
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New Suprasil mirror from LMA, posted by Loïc Amoudry at Optical room about lasers and optics
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14/05/19:
New Suprasil mirror received. It will replace the S-BOX suprasil mirror on ThomX which was already replacing the sapphire mirror.
First finesse measurement: 14000 |
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Finesse after cleaning (new suprasil mirror), posted by Loïc Amoudry at Optical room about lasers and optics
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15/05/19-20/05/19:
Cleaning of the mirrors:
Initial finesse 14000 @air |
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Finesse measurement by decay time technique, posted by Ronic Chiche at Optical room about lasers and optics
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5 Files attached:
- Note on the technique and results for the present cavity on 2019, May 21th : F ~ 18 000
- 2Tektronix scope raw data |
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Transmission of Sapphire mirror, posted by Loïc Amoudry at Optical room about lasers and optics
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| See image. |
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Polarization, posted by Loïc Amoudry at Optical room about lasers and optics
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Polariztion measured with Input vertically/horizontally polarized (~100% DOLP)
- Transmission (P4) locked on cavity horizontal polarization is ~50% linearly polarized and ~50% unpolarized ?
- Transmission (P4) locked on cavity vertical polarization is ~50% linearly polarized and ~50% unpolarized ? |
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telescope for Koheras, posted by Huan Wang at Optical room about lasers and optics
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telescope of Koheras is removed, information record here:
- distance between collimator edge and -50 lens mount edge is 14.7cm,
- distance between another edge of -50 lens mount and +250 lens mount edge is 14.3cm, |
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New design for PDH boxes, posted by Ronic Chiche at Optical room about detectors and electronics
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A new design has been studied for the 5 PDH boxes to better match the low (33MHz) repetition rate of the ThomX laser.
the 5 PDH boxes have been modified and tested (see the attached report).
A mixer has been integrated to the PDH box for a more simple use. |
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Onefive 33MHz unmodelocked, posted by Loïc Amoudry at Optical room about lasers and optics
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Oscillator randomly unmodelocked on 3rd july afternoon (during oscillator power measurement, maybe a reflection from the powermeter power filter
?)
Modelocked this afternoon by putting Onefive motor and phase at reference on the PTC software. |