Evan, Stefan, Kiwamu, Lisa There has been some confusion about factors of two in previous entries, so here are our "final" numbers: - Pin = 8.8 W entering the IMC, measured on the PSL table - with PRM aligned, R = 98.6% - from Paul's calibration of the MC2Trans diode (we measured 645 uW), it looks like there is T = 88% from the PSL to the transmission of the input mode cleaner; - given the HAM1 path, we expect 1.25% of the REFL power to reach the LSC RF diode P_exp = 8.8 * 0.986 * 0.88 * 1.25e-2 = 95 mW; LSC in vac REFL A (LSC RF PD) (1.25% of REFL power) = 15900 counts (maximum found by moving RM2) ==> 15900 [counts] * (1/1638) [V/counts] * 2 [diff to single input] * (1/200) [1/Ohm] * 0.8 [W/A] = 78 mW LSC REFL AIR A (LSC RF PD) (0.625% of REFL power) = 7955 counts ==> 32.5 mW measured directly in front of the diode on table ==> 7955 [counts] * (1/1638) [V/counts] * 2 [diff to single input] * (1/200) [1/Ohm] * 0.8 [W/A] = 39 mW LSC REFL AIR B (BBPD) (0.625% of REFL power) = 21770 counts ==> 34 mW measured directly in front of the diode on table ==> Conclusion : The discrepancy between what we see and what we expect is not a factor of 2, but more like 20%-30%, and in vac and in air diodes gives us consistent numbers.