Aritomi, Marc, Matteo

Today we cleaned a bit the computer room and brought the KAGRA spare to the clean room. We putted first contact on the surface facing outside the protection box.

Then, we followed the realignment procedure described on the wiki and installed the surface reference sample to realign the setup with the goal of reproducing the calibration done in elog 1619 : R_surf = AC_surfref/(DC_surfref*P_in*abs_surfref) = 16.9 [1/W]

First, we putted the surface with the sample name facing the laser (PS : mirror center in z is 38 mm). Results are presented in figure 1 and gives (with abs_surfref = 0.22) : AC_surfref = 0.17V, DC_surfref = 3.91V, P_in= 16mW -> R_surf = 12.4 [1/W]

Then, we flipped the reference sample (PS : new center at 33.25 mm) to check if it could explain the discrepancy wrt to elog 1619.

During a scan, there were some troubles with some connections and we got several error messages from LabView... We had to restart the computer to use LabView again but there is still some troubles with the power-meter ( detected but not able to connect to the computer)

The result of this configuration is presented in figure 2 and gives : AC_surfref = 0.31V,  DC_surfref = 4.01V, P_in= 15mW -> R_surf = 23.4 [1/W]

This time the AC measurement is not as symmetrical as expected so we'll further tune the alignment tomorrow.