Today; replaced the M1 SBox mirror with M1 from gamma factory , following the previous alignment.
Removed all mirrors and cleaned them one by one.
Started with no M1, placed M2 did its alignment through M3 pinhole, then placed M3 aligned it through M4 pinhole, then placed M4 aligned it through M1 pinhole.
Placed M1 Gamma factory at the end
Note: mirror is new was not used before, took image on microscope there was no dust in the center, but there was little on the edges (cleaned it using spin-coater)
beating of fundamental mode observed (at M2 transmission) immediately with very higher order modes, slight adjustment on M4 suppressed them.
The beam is not circular and still has some deformation, M1 was changed, so it could be a damaged point at one of the other mirrors (to be investigated tomorrow)!!
No significant damage seen on the other mirrors.
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Manar Amer wrote:
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Last week In FP cavity we had all SBox mirrors including the damaged M1 mirror.
The beating was observed with just a slight adjustment on M4 alignment.
In addition, it was also observed while driving the piezo of the CW laser.
In the attached image of the beam at transmission point at M2 mirror, the shape of the beam is deformed.
one of the factors could be related to the damaged spot on M1 mirror. The deformation position can also be seen in the higher order modes.
after changing the injection mirror to Gamma factory M1, this deformation should disappear.
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Finished the alignment of the SBox with M1 of SBox placed, to be changed to gamma factory mirror later
Observed what seems to be transmission through M2 mirror, to be confirmed. image attached shows it
a PowerPoint attached showing the details of today's work.
| Manar Amer wrote: |
- Adjust the placement of the Irises (done at the start of the day, adjusted at the end when M1 mirror was placed)
- Improvement on the Ma1 and Ma2 (The Alignment Mirrors)
- Improves the alignment a bit. There is an observation where there is no symmetry in the image, concluded to be because of the pinholes that are usually used for the alignment the circle cut is not symmetric (took images on phone of pinholes)
- This explains why, for the pinhole used on M1, we see a little more symmetry than the pinhole used on M2.
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- Placed M1 mirror from Sbox (with damage spot in the middle), after cleaning it using the spincoater, only used to adjust the injection into the mirror where it will give Horizontal displacement due to the thickness of the mirror.
- Last position of the motors attached
- Installed the 2 dielectric mirrors for the reflection line
- Did a rough alignment for the reflection line to have it exit through the reflection window.
Note about mirrors : They were cleaned a year a go and placed in the boxes. When opened the box and seen under microscope they were very dirty with dust particle
Specially from the back, I believe the boxes have dust in them (to be verified under the UV light / Microscope !!!!!!!! )
| Manar Amer wrote: |
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Remember to update the position of the reference Irises tomorrow !!!!
| Manar Amer wrote: |
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After pointers and Advice from Aurélien,
improvement of the beam alignment through M1 and M2 irises was done.
To improve the image on the beam profiler, I cleaned the alignment mirrors and the windows using pure ethanol and optical lens cleaning tissue,
a significant improvement after cleaning the inside of M2 Window. Images have less dust diffraction rings.
Attached new images of the beam:
- New Ma1 and Ma2 motor position
- After M1 pinhole optimized (saturated)
- After M2 and M1 pinhole optimizing (saturated and not)
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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
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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.
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