KAGRA Logbook

Reports 1-1 of 1

IOO (Laser Bench)

yutaro.enomoto - 18:53 Tuesday 16 May 2017 (2755)

Preparing beam for Reference Cavity

Today we started reference cavity (RefCav) related work.

PMC transmission light will be used for RefCav. Since we do not have PMC yet, we need to somehow mimic PMC transmission light.
Then we picked off some light from main path (just after M3) and tried to re-shape the beam profile with two lenses (f=100 and f=150).

The current profile is shown in the attached figure. Target profile is characterized by w_0 = 706 um and z_0 = 3525 mm.
According to this result, tomorrow I am going to move the second lens by ~ +10 mm to make the profile closer to the desired one.

Images attached to this report

Comments to this report:

yutaro.enomoto - 18:38 Wednesday 17 May 2017 (2763)

I made a mistake in the previous log; the focal length of the second lens is 125 mm.

[Nakano, Kasuya, Enomoto]
According to the result we got yesterday, we moved the socond lens by 9 mm. Attached is the current beam profile. It seems very nice.
Top view of the two lenses are also attached.

Images attached to this comment