Simon, Pengbo

Today we started the IU adjustment with the bulk reference trying to find the maximum of AC/DC value.

We start setting the IU back to initial position ( -> 70 mm) , decreaing the distance then find the maximum at 54 mm with a value of 0.0158. We stopped here since the maximum position is too far away from the achievable distance towards measuring KAGRA-size samples.

Then we moved the first lens of the telescope 2 mm away the second lens and adjust the crossing-point with pin-hole and surface reference sample(IU back to 70 mm). We fastly found it and adjust the AC to be maximized with second lens -> R_surf = 16 1/W.

After that we did another adjustment of IU to find the AC/DC maximum, and found it  was at 69 mm. We make a bulk reference scan and get R_bluk = 0.713 cm/W. Then we start the absorpiton measurement on KAGRA-size #7 sample.