Participaint: Eleonora, Matteo Barsuglia and Yuhang.

As we found before, the transmissivity of mode cleaner is not as expected. We also found for different Finesse requirement, we can have different tolerance of reflectivity error.

According to the measurement result of entry871 and entry548, we firstly get the reflectivity of mirror (r) and then we use this result and scan the reflectivity amplitude from 0 to 0.13.

We put this difference to each mirror as delta/2, for example we use r_1=r+delta/2, r_2=r-delta/2. However, when we convert this amplitude difference to power difference, we bring back a factor of 2. So they balance.

We also plot the case for Finesse as 100. As the experience of Matteo Barsuglia, this Finesse can give us 99% of clean to have TEM00. And we can increase reflectivity difference tolerance dramatically. For details, refer to attahced figure.

We also investigate the reason of higher transmission with lower Finesse. The reason is we loss some of the power through the end mirror of mode cleaner. The higher the Finesse is, the more losses we have.