Marc, Matteo, Yuhang
We used the green light to check possible dust on the mirror and took a picture after already using the air dust once.
The mirror is really dirty...
We then used again the air dust and could remove most of the large dust particles but not the smallest one (not visible on picture so no 'after picture').
We can still see the ethanol/acetone trace at the mirror edge so the mirror got dirty either during shipping or during the few weeks it stayed inside the clean room without cover.
We will clean it with first contact after the golden week.