attenuation with 1 mating sleeve :

green jacket fiber : -0.4 dB

blue jacket fiber N°1 : -0.5 dB
blue jacket fiber N°2 : -0.27 dB
blue jacket fiber N°3 : -0.13 dB
blue jacket fiber N°4 : -1.4 dB

we should try to polish at least the fiber 4 which seems faulty.

with Alice, we installed the Menhir 160MHz oscillator on a breadboad placed on top of 4 damped feet around the amplifier.
we will do an heterodyne phase noise measurement vs the CW OEwaves oscillator.

the power at the output of the Menhir oscillator is about 150mW.
after injection in the fiber (N°3 blue jacket), we got about 75mW.

we installed the 2->1 coupler to make the beating.
BE CAREFUL, the coupler is polarization sensitive, so we add a half waveplate in the Menhir path to adust the polarization on the coupler, otherwise the output power can be very low.
the coupler attenuation is ~ 3.5dB on both inputs.

the OEwaves power is ~16mW at the input and we measured ~7mW at the output of the coupler for this channel.
the Menhir fiber coupled power is ~75mW and we measured ~26mW at the output of the coupler for this channel.

measurements made with Alice:

comparison between the CW OEwaves oscillator phase noise measured last week (2 measurements done with AOM, in red and orange) with the one made in 2022 (without AOM, in blue).
one observes a degradation of the performance of the oscillator by ~10dB in the region of interest 100Hz-100kHz

comparison of the Menhir 160MHz phase noise with the CW reference.

- in blue, the oscillators are placed on top of an aluminium breadboard, placed directly on an optical table (measurement made in june)

- in red, the oscillators are placed on top of an aluminium breadboard, placed directly on top of 4 feet with Thorlabs AV4/M Sorbothane dampers, above the NeoLase amplifier (measurement made last week)

=> similar behavior with phase noise increasing around 1kHz, compared to the reference.

after the previous measurement, we installed similar dampers, than the ones used belows the aluminium breadboard, placed below the 4 Menhir 160MHz "feet", in contact with the aluminium breadboard.

 - in red, phase noise measurement with the Sorbothane feet below the Menhir laser and below the aluminium breadboard.

 - in blue,same measurment with an additionnal heavy mass placed in the middle of the breadboard.

• 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 the center of the mirror, this was due to reflection of light inside the box. The reflection from the mirror was reflected on the metal inside the box and it was measured by the power meter.

               (so for this setup we only took measrements for T along the center of the mirror)

The file stating the measurements is : Test Cavity _ Mirrors transmission _ Inside box

=======================================================================

• Tuesday 15 December 2020 :  Second Test - Outside Box
  • The setup for T test was moved outside the metal box with the same distances between the injection beam and mirror ~ 50 cm. and the distance between the injection laser and the mirror next to it ~ 9 cm.
  •  
  • Observation for T is done at full angle and at half angle of reflection ( the mirror was tilted to achive this )
  •  
  • we observed that after each change in the distance from the center the power meter needed to be aligned to have the max power.
  • after doing all the measurements for the range from the center we made it again for the center only and the consistance of the transmission was good.

The file stating the measurements is : Test Cavity _ Mirrors transmission _ outside box

note: the laser used for the test is the Koheras

details on the pwer used, mirrors, power meter, filters, ....etc are shown in the Excel data sheets

Done By : Loic , Manar and Ahmed

• We started measuring the phase noise on the OEwaves CW laser.
  • Class 3b
  • wavelength 1.5 um
• The procedure is done using self coupling of the laser
  • splitter 50%-50%\
  • delay line 100 m 
  • all fibers are PM type (polarity maintained)
  • Photodetector is "lab buddy", very fast diode.
  • Note: différance from schematic (we did not use a low pass filter)

a correction on the wavelength of the laser  it is 1030 um 

correction on unit 1030 nm

An Initial cleaning of the KBoX outside was done, All the optics and mechanics placed that were on the table were removed.

Only the old Mitylaser amplifier remains on the table.

Since we will be using the ThomX Celia amplifier, we will remove it and place it in a secure location (to be decided).

Tomorrow a cleaning of the inside of the cavity box is to be done.

The cleaning was done twice with half an hour interval between the two times
reading on the dust meter was taken after each time, and it was zero averaged over a 10-min

Migthylaser amplifier has been moved from the SBox table to the PLIC table.

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.

The inside of the cavity was cleaned today. It was very dirty and had big dust particles and fibers inside.

Cleaning was done for everything; wall, floor, fixed mounts, wires (still have some dust difficult to remove), edges.

The dust meter average was measured outside the cavity (2471 p/m3 av 6 min)  and inside after cleaning (1424 p/m3 av 10 min).

The cavity was left open under the clean air flow, will observe it under UV, clean and measure Dust tomorrow.

Images attached are after cleaning.

Objects inside the cavity at the moment :

• 4 main mirror mounts
• 4 mirror fixers on mounts and 3 screws each (total 12)
• 2 reflecting mirror mounts
• 2 dielectric mirrors (mounted and to be cleaned)
• two mounts for D-shaped mirrors.
• 2 D-shaped mirrors (unmounted, and they will need cleaning)
• 2 metal irises (pinholes)

After an overnight where the cavity box was left open, a measurement of the Dust meter was taken:

Outside on the optical table on direct air flux (1701 p/m3 Av 10 min) and

Inside the cavity box (998 p/m3 Av 10 min)

The dust inside the cavity has decreased by ~ 30 % for 0.3 u particles.

Note: the cavity box is still open.

The dust meter cap was cleaned using Alcohol, and using the filter white cap the dust count was (0 Av. 10 min)

After the dust counter was hand held in direct airflow, it counted (1581 p/m3 Av. 2 min).

I tested the count also in the SAS, and it counted twice the amount ~ 4500 p/m3

Note: discussion on the next steps to take for the airflow filtering !!!!!!!!

Dust measurement done today on  top of the SBox average 10min

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 .

After multible rounds, the result in the images was obtained. there is still a significant amount of dust particles (not all could be dust!!).

Not sure if the reason is the cleaning method ?? will invistegate it more !!!

Starting with the alignment of the KBox using CW Koheras.

The size of the CW output from the collimator at 1 meter from is ~ 2.4 mm, to be adjusted with lenses to match the cavity !!! (attached image)

For the 2 alignment mirrors, I am only able to control 3 axes for now (motor issue for the fourth to be fixed !!) , Horizontal and vertical for Ma1 and Horizontal for Ma2(closes to injection window).

Started with only irises placed on both the M1 and M2. Placed a beam profiler at the window behind M2 to observe an output beam.

Motors position for the 3 axes and beam shape and position after M2 attached.

SBox alignment, using CW laser Koheras power 1 mW

• Finished M1 and M2 alignment using the diffraction patterns seen on the beam profiler,  the beam fit is not very good ?? (image taken)
• Positions of Ma1 and Ma2 motors are registered (image taken)
• Placed Fixed 2 irises at M1 window and M2 window (Image taken while both are closed)
• Distance between the collimator and beam profiler ~ 2 m
• Distance between collimator and M1 diaphragm   ~ 1 m
• Distance between collimator and M2 diaphragm ~ 1.6 m