In order to assess the impact of losses on the low transmissivity of the green mode cleaner (see entries #850, #892), we asked Laurent Pinard (at LMA) to characterize one mirror from the same batch of mirrors used in input/output.
Here the results he found at 44° at 1064 nm (S-pol):
- absorption: 0.7 ppm
- average scattering: 15-20 ppm
Since the losses due to scattering are proportional to (1/lambda)^2, at 532 nm they are expected to be a factor 4 larger than those measured by Laurant. This means 60-80 ppm at 532 nm.
By computing again the cavity transmissivity with the formula:
T = ((t_in*t_out)/(1-r_in *r_out *r_end))^2 where R_ in = R_out = 0.992 and this time T_in = T_out = 1 - R_in - Losses.
the transmittivity changed only by few percent (from 92% to 90%).
The conclusion is that losses don't seem to be the cause of the low trasmissivity of the green mode cleaner.