Sheila and I are continuing to check various PD calibrations (82260). Today we checked the POP A LF calibration.
Currently there is a filter labeled "to_uW" that is a gain of 4.015. After some searching, Sheila tracked this to an alog by Kiwamu, 13905, with [cnts/W] = 0.76 [A/W] x 200 [Ohm] x 216 / 40 [cnts/V]. Invert this number and multiply by 1e6 to get uW/ct.
Trusting our recalibration of IM4 trans, we have 56.6 W incident on PRM. We trust our PRG is about 50 at this time, so 2.83 kW are in the PRC. PR2 transmission is 229 ppm (see galaxy optics page). Then, the HAM1 splitter is 5.4% to POP (see logs like 63523, 63625). So we expect 34 mW on POP. At this time, there was about 30.5 mW measured on POP according to Kiwamu's calibration.
I have added another filter to the POP_A_LF bank called "to_W_PRC", that should calibrate the readout of this PD to Watts of power in the PRC.
POP_A_LF = T_PR2 * T_M12 * PRC_W, and T_PR2 is 229 ppm and T_M12 is 0.054. I also added a gain of 1e-6 since FM10 calibrates to uW of power on the PD.
Both FM9 (to_W_PRC) and FM10 (to_uW) should be engaged so that POP_A_LF_OUT reads out the power in the PRC.
I loaded the filter but did not engage it.
More thoughts about these calibrations!
I trended back to last Wednesday to get more exact numbers.
input power = 56.8 WPRG = 51.3POP A LF (Kiwamu calibration) = 30.7 mWpredicted POP A LF = 0.054 * 229 ppm * 56.8 W * 51.3 W/W = 36 mWratio = 30.7 mW / 36 mW = 0.852If the above calibrations of PRG and input power are correct, we are missing about 15% of the power on POP.