Sheila, Pep

The attached plots show the comparison between H1:GDS-CALIB_STRAIN and the OpLev channel (H1:SUS-ETMY_L3_OPLEV_SUM_OUT_DQ) for different glitch events, found in HVeto in this day: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170419/detchar/hveto/. We also show a comparison between these channels for times when the OpLev was not glitching.

To get these results, we have assumed that the only force on the mirror is the pressure radiation force of the OpLev laser. The equation is:

F=2*P/c=m*a,

where P is the power of the laser, c is light's velocity, m is the mass of the mirror (taken as 40 kg) and a is acceleration. In order to find the power of the laser, we have to use the relation between the counts detected by the QPD and the power, which is (DCC T1600085):

P = Counts * (40 [V] / ((2^16) - 1)) * (1 / Transimpedance [Ohms]) * (1 / Whitening Gain) * (1 / Responsitivity [A/W]) = Counts * 7.6295e-09 for the H1:SUS-ETMY_L3_OPLEV_SUM_OUT_DQ channel.

The transimpedance values can be found in DCC T1600085, the whitening gain values in dB can be found here in DCC T1500556-v4. These values have to be converted from dB using 10^(x/20). The responsitivity is 0.4, and can be found here: http://www.hamamatsu.com/us/en/product/alpha/S/4106/S5981/index.html#1328449179787
(the laser is at 635 nm).

After calculating the acceleration, we calculated the asd of this time series using gwpy, and after that we divided by the square of the frequency to have the displacement of the mirror. To compare these values to the ones in DARM, we divided by 4000 m to get the strain.