Message ID: 14451
Entry time: Wed Feb 13 02:28:58 2019
In reply to: 14450
Reply to this: 14454

Author:

gautam

Type:

Summary

Category:

Loss Measurement

Subject:

Y arm loss

Attachment #1 shows estimated systematic uncertainty contributions due to

ITM transmission by +/- 0.01 % about the nominal value of 1.384 %

ETM transmission of +/- 3 ppm about the nominal value of 13.7 ppm

Mode matching efficiency into the cavity by +/- 5% about the nominal value of 92%.

In all the measurements so far, the ratio seems to be < 1, so this would seem to set a lower bound on the loss of ~35 ppm. The dominant source of systematic uncertainty is the 5% assumed fudge in the mode-matching

To do:

Account for uncertainties on modulation depths

To estimate if the amount of fluctuation we are seeing in the reflected signal even after normalizing by the MC transmission, get an estimate of statistical uncertainty in the reflected power due to

Pointing jitter - is there some spec for the damped angular displacement of the TT1/TT2?

Cavity length in-loop residual

Bottom line: I think we need to have other measurements and simultaenously analyse the data to get a more precise estimate of the loss.