***** Continuation of the alignment ---- FP Cavity Open --- ****
The cavity was put under outer pressure and was opened for the alignment
The alignment was done using CW koheras infrared laser and the inside mirrors irises
we observed the beam output centered at S2, S3 and P4
transmission from S4 to P1 was aligned at the center of P1 iris and an outside reference was fixed, then P1 mirror was placed, and we aligned the reflection with the transmission.
....... After the interior alignment, the cavity windows were closed ....
A beam profiler was placed at P4 transmission -----> nothing observed even with a piezo drive on the CW infrared laser
observed a beam output at S2 and S3, but the fundamental mode is not seen, or even a higher order mode (which we can't explain, as the beam is centered on the mirrors)
images show the output at S2 and S3
| Manar Amer wrote: |
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The alignment is on hold until next week 17th - 18th Jan
an Alignment attempt will be done when the ring part close to the FP cavity is opened.
| Manar Amer wrote: |
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Note the direction of injection is M1 - M2 - M3 - M4
P1 - S2 - S3 - P4
The injected beam is aligned at the center of the irises placed at the windows mounts of mirror M1 (Injection) and M2(spherical)
At Transmission of M2 : in addition to centered beam, we observe diffraction which interferes in observing the beating at M2 output
(could be diffracted beam from the metal pipes inside or from the D-shaped mirror installed inside)
At Transmission of M3 : we observe a beam output could be part of TM00 mode (the shape is distorted !!)
suspicious reasons :
- when we have a frequency sweep on the CW(Koheras) piezo; we observe it beating (when increasing the drive it is increasing in intensity)
- when we adjust the alignment mirrors; the beam doesn't change position and only its intensity changes
continuation with the alignment and try to eliminate the diffraction and find the shape of the beam.
A manual change in the D-shaped mirror position to remove any possible effects from it.
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