A continuation of the alignment process was done, there was change in it due to variation in temperature,
it was done using the semiconducting laser, and we were able to obtain an output at M2.
2 references were placed before the alignment mirrors Ma and Mb , to fix the line when changing from semiconducting laser to CW "koheras"
Another reference was placed at the reflection line.
Then we changed to CW laser and placed a beamprofiler at the output of m3 trying to observe the cavity mode, but with no success
(there was a shaped observed which we thought of as the cavity mode, but it changed position when moving the alignment -- > not mode (the cavity mode only changes intensity with alignment mirrors, or disappears))
later a continuation will be done for the alignment using 2 beamprofilers
Note: a reference file of the mirror positions was saved on the command computer and a laptop dedicated to ThomX cavity is placed in the casmate
| Ronic Chiche wrote: |
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This afternoon, we continued the alignment of the red laser.
we did it using the 2 final injection mirrors.
we still see a clear transmission after M2, a weak transmission after M3, and almost nothing after M4 due to the power loss going through the dielectric injection mirrors (which are not optimized for red wavelength).
we placed 2 new iris in the path before the injection mirrors to help the alignment of the Koheras with the periscope.
and we prepared different equipments to continue next time: scope, photodiode, beam profiler, power meter....
| Ronic Chiche wrote: |
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as the iris used to locate the FP-cavity axis have been removed before moving the table inside the Igloo, we have to find again this FP-cavity axis.
this morning with Viktor, we started to make the alignment of the FP-cavity with a red laser using only the "input window" iris mount built by Yann.
we used a 4 axis mount for the red laser, plus a 2 axis mount for the injection mirror (we didn't use the final injection mirrors).
the red laser is clearly visible in the transmission of the 3 "output mirrors" of the cavity.
1- we made a pre-alignment of the red laser using the reflection on the input window
=> one can see the beam at the output of all the 3 "output mirrors", but not centered on their respective windows.
2- we made a final alignment of the red laser to have roughly the beam going through the middle of all the 3 "output windows".
(rough alignment as we don't have the iris mounts for these windows, yet).
3- we put a second iris in the input path to fix the input beam axis relative to the FP cavity axis.
(the first iris is the one used on the "input window" iris mount).
this afternoon, we plan to replace the mirror used by the final injection mirrors of the cavity.
and then, use the Koheras laser to try to get some resonances.
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