KAGRA MIR (Absorption)
MarcEisenmann - 11:36, Friday 18 June 2021 (2586)
cleaned viewport absorption measurement

I brought in PCI the cleaned viewport. Aso-san helped me confirm that the cleaned surface is the one where there is no more indium at the edge.

I installed this viewport on the holder with the correct surface facing the lasers.

I realigned DC and started the measurement.

The procedure I'm planning to do is to start from 28 mW and increase step by step up to 600 mW (eg 100,200,30, etc..)

I did the first measurement with 28 mW and got the result attached in figure 1.

It seems that we don't have clear signal on most of the map. But there are few points where the absorption seems quite high.

Sadly I was not present in the PCI during this measurement so I can not confirm that there was no saturation of the lockin so these maximal values of absorption are not reliable.

A possibility for further inspection is to repeat this measurement with same power but only around the dirty spots and make sure that the lockin is not saturating.

Depending on the absorption value of these spots, include them or not in the maps with higher laser power.

Images attached to this report
2586_20210618043416_absorption.jpg