[Nagano, Nakano]

Today we continued the preparation of the beam pass bypassing the PMC.

At first, we calculated the mode matching using the yesterday data and decided to use two concave lenses, f=500 mm and 750 mm.
The target beam is the same as main pass and is shown in the attached figure.
In addition of the two lenses, the magnet flip mirror was also installed to switch the main and bypassing pass depending on the purpose.
Then we aligned the beam.
The alignment was almost done.
The beam goes to IMC and we can see the resonance in the IMC REFL signal.
The fine tuning has not been done and we will do it tomorrow.