[Optics]
I adjusted the lenses' positions for mode matching.
I tried to measure the beam profile inside the cryostat chamber, but it was too difficult to measure the distance.
Fortunately, some amount of the beam was reflected by a PBS in front of the chamber due to the imcomplete alignment of FI and it propagets on the optical table.
The profile of this kicked beam is almost same as the beam which incoming to the chamber.
Therfore I will use this beam to measure the beam profile.

[Cryostat]
I assembled another window for 80K shield as attached picture.
I am planning to use two 80K shield windows for my experiment.

[Next Step]
Measure the beam profile.
Install a FP cavity to characterize fused silica mirrors.