In response to the recent hot topic. Using measurement results (see 17442 and XXXXX), I analyzed the current power budget situation on the green X. The detail is discussed in the attached document. In short,
Assumed:
- GreenX power input to the invac-POP-POM (just after the perisocpe): ~7 mW
- ITMX reflection at GrRFPD: ~ 2.5 mW
- ETMX reflection at GrRFPD: ~ 13 uW
Derived:
- It seems the test mass transmission at 532 nm would be ~ 0.072, which is well consistent with some values Enomoto-kun told us yesterday in slack; accoding to him, these values are measurement and Hirose-san had told him in the past:
| HR transmission at 532 nm | AR reflectance at 532 nm | |
| ETMX | 7.1+/-0.2% | 0.6% |
| ETMY | 7.2+/-0.2% | 0.6% |
| ITMX | 7.5+/-0.4% | 0.5% |
| ITMY | 4.3+/-0.4% | 0.5% |
- In addition, my estimation says ~ 1-0.62 = 0.38 power loss in the one-way path from the POP table to ITMX... is this explainable with some theories???? The GV window clipping?? (maybe no... 5cm radius window vs 3.5cm/sqrt(2) radius beam...) Note that we have not yet done sweeping (PR3 and POP-POM (invac?)) at the same time to search for the maximum power at several locations (GrRFPD and TMSX-GrPD)
By the way, the table above should be very important information, which is not found in wiki (there is only a nominal or in-specification values 0.06) as of today. It should be shared in a proper way... How should I do??
