I made OpLEv windshields for PR3 because we had an experiences that proper windshield can decrease OpLev glitches drastically.
After the construction, I measured spectra of PR3 OpLevs with LOCK_ACQUISITION state (fig1).
Blue and red represents spectra before and after windshields construction, respectively.
As you can see, noise level was improved a lot.

Figure 2 shows the time series of OpLev signals.
The graph before t = -1h 10m shows the signals without windshields and that after t = -23m shows the signals with windshields.
The glitches seem disappeard, at least very large glitches (larger than 1urad) doesn't appear more than 20 minutes; very good.