This is just a check to see if the photocurrent in the HAM1 LSC POP photodetector is what we expect it to be from the power levels and optics transmissions.

From G2200705, the LSC-POP_A_LF is still pretty linear at 40 W input, so I'll use that power level; however I think it needs to be increased by the 9% the is mentioned on slide 5. So,

Recycling cavity power:

P_inc*PRG = 40 W * 1.09* 52.5 = 2.3 kW

Transmission of PR2 is 230 ppm (from galaxy optics page), so

P_POP = 2.3 kW * 230 ppm = 0.53 W

In HAM3, the POP beam reflects off 3 HR steering mirrors (no splitters) and is directed to HAM1. So 0.83 W enters HAM1. In HAM1 (D1000313), the beam goes through a periscope,  reflects off an HR1064, then passes through a 10% transmission splitter (E040512-B3), then is steered by another HR1064 mirror to the POP photodetector. So neglecting small losses from the HR mirrors, the power incident on the detector is 10% of the full POP power, or:

P_pd = 53 mW

The plot on slide 3 of G2200705 shows 47-48 mW at that input power. But of course what is actually measured is the photocurrent, and I don't know what value of quantum efficiency is used to calibrate this channel to power. For a QE = 1, 53 mW would produce 45 ma of photocurrent (or, 48 mW would produce 41 ma). So it looks like the LSC POP detector is seeing, and measuring, pretty close to what we expect for that beam - though maybe 10-15% less.