These are not the angular test parameters that we're looking for:
recall that what we want is the low frequency beam spot variations and the feedback to be limited to a small high frequency band.
e.g. only inject noise at 40-50 Hz, not loud enough to find at 2x the injected frequency.
It should NOT be the case that the high frequency injected noise be dominating the RMS.
The coupling should be ~1e-3; some combination of beam spot mis-centering and beam spot motion.