The units were still off in my previous post. Here's the corrected, sanity-checked version:
| Camera IP |
Calibration Factor |
| 192.168.113.152 |
85.8 +/- 4.3 pW*μs |
| 192.168.113.153 |
78.3 +/- 3.9 pW*μs |
I estimated the uncertainties based on a linear fit to the data I recorded with 75nW incident on the CCD and assumed a 5% uncertainty in that number. This is just an upper limit, to be safe. I had calibrated the power reading placing the Ophir power meter where the CCD would otherwise be and comparing it to the PD voltage of a picked off beam. In my previous figures the axes were mislabeled, so I reproduce them here:
 
Using the current camera position I recorded 50 exposures both with and without beam (XARM locked vs PSL shutter closed) and averaged the images to see how much the reading fluctuates. The exposure time was 10 ms, which left the maximum reported pixel value in all exposures below 3800 out of 4096. The gain setting was 100, which is what I used to calibrate the CCDs.
| Counts with XARM locked |
2.799 +/- 0.027 x107 |
| Counts with shutter closed |
3.220 +/- 0.047 x106 |
| Power on CCD |
193.9 +/- 2.2 nW |
| Power scattered into 2π (*) |
254 +/- 39 μW |
| ETMX scatter loss (**) |
25.4 +/- 3.9 ppm |
(*) I calculated the lens positions to focus at a plane 65cm from the front lens. We're pretty close to that, but I can't confirm the actual distance easily, so I assumed a 5cm error on the distance, which is where most of the error is coming from. This is also assuming uniform scatter.
(**) This is assuming 10W of circulating power |