[Sudarshan, Sheila]
We made two transfer function measurements between the A2A L2 drive align filter and DARM with beam spot centered and beam spot moved at 2 watts input power. We drove only in Pitch. These measurments were done in an effort to understand the angle to length coupling of PUM stage. We will compare these measurements with the models to see how well they agree. The screenshot of the transfer function is attached below. Model comparison to follow soon.
[Sudarshan, Sheila, MattB]
The attached plot shows the comparison between the measurement, made above, and a model. The measurment seem to agree pretty well with the model in magnitude. There is some phase discrepancy, about 20 deg. at 20 Hz, between the measurement and the model. We don't yet understand why. P.S. The green shade on the plot is the frequency regime where the injections were made to make this measurement.
