Peter, Sidd
Counts_to_volts = 40/2^16
Transimpedance = 20,000
Responsivity = 0.35
Oplev_from_ETMX = 5.6 m
Diode_area = 10x10 mm^2
Angle_from_test_mass = 7.6 degrees
Power_scatter = Counts x Counts_to_volts x (1/Responsivity) x (1/Transimpedance)
Solid_angle = diode_area/(Oplev_from_ETMX)^2
BRDF = Power_scatter/(Arms_Power x solid_angle x cos(angle_from_test_mass) )
I compared the ETMX Oplev BRDF between the 75 W and 60 W configuration. The details are below, the first three days are when LHO operated with 75 W and the last three days are with 60 W input power. I do not find any significant change in the ETMX Oplev BRDF.
|
Date |
Power (KW) |
Counts |
Power_Scatter (µW) |
BRDF |
|
2023-06-05 |
430.7 |
4960 |
432.4 |
3.18e-4 |
|
2023-06-07 |
439.2 |
4964 |
432.8 |
3.12e-4 |
|
2023-06-14 |
434.24 |
5016 |
437.3 |
3.19e-4 |
|
2023-07-28 |
370.1 |
4243 |
370 |
3.16e-4 |
|
2023-08-10 |
364 |
4177 |
364.2 |
3.17e-4 |
|
2023-08-13 |
368.4 |
4206 |
366 |
3.14e-4 |
The calculation is in the notebook
Just to clarify, the Counts term in the Power_scatter is the difference in the Oplev counts between locked and unlocked ifo.