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Updated: Mar 3, 2026

Measuring the Interaction Force Between a Droplet and a Super-hydrophobic Substrate by the Optical Lever Method
Published on: June 14, 2019
Measurement of fluctuations of electrostatic force acting between a dielectric plate and an electrostatic drive
D V Koptsov1, L G Prokhorov1, V P Mitrofanov1
1Faculty of Physics, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia.
Abstract:
A setup for the measurement of the noise associated with the interaction of an electrostatic field produced by an electrostatic drive with a fused silica plate is presented. The fused silica plate is a part of a 63 Hz high-Q torsional oscillator. Its oscillations are measured by an optical interferometric sensor. The measurements are PC-controlled and fully automated. A digital post-processing scheme is described, allowing the calculation of the plate rotation angle fluctuations and the evolution of the charge distribution on the surface of the fused silica plate. The characteristic surface charge relaxation time has been purposely kept small on the order 103-104 s. The upper limit of the investigated noise has been obtained. We used this result to estimate the electrostatic drive noise in the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) gravitational wave detector at frequencies of about 18 Hz. The obtained upper limit of the strain amplitude spectral density is (1±0.13)⋅10-22Hz-1/2.
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