[Kyle Sheila Arnaud]

This evening, we took a close look at the ETMY optical lever spectra, which showed interesting features in the pitch and yaw signal, as well as in the sum, (cf first screenshot)
Thinking it might be due to the laser, we went down to EY, and tried recycling it, but unfortunately it didn't change anything (red and blue = before, brown and pink = after). Maybe we should try the same thing with the electronics.

Second attachement shows the current difference between EX and EY in the oplev pitch. EY signal still looks very noisy from 1Hz certainly because of the current ground activity (fans, pumps...)

Finally, this morning Kyle turned off the turbo vacuum pump to make sure it was causing the 29.57Hz peak in the ISI T240 and the oplev spectra. Third attachment shows difference on/off (orange ON, purple OFF) in the oplev pitch spectra.