Fig. 2: Calibration.
From: An optically driven microstructure for torque measurement in rotary molecular motors
Experiments with a four-arm light-mill trapped in bulk fluid. a, b Angle as a function of time for different values of the laser power. Brownian fluctuations are clearly visible when laser power is low. c x−y trajectory of the light-mill structure for P = 0.003 d Mean squared displacement of the angle relative to the tracks in (a). The black dashed line represents a linear fit of the blue curve for t < 0.01 s with angular coefficient 2kBT/γϕ. e Translational mean squared displacement on the x−y plane for short times. The black dashed line plots a linear fit with angular coefficient 4kBT/γxy. f Derivative of the angle for P = 0.05. The blue line is the average of ω within small ϕ intervals. Black dashed line is a fit to Eq. (2)
