(a) Photograph showing the main torsion balance components together with the Casimir sphere (also shown in the inset). (b) Photograph of the levitation bearing which is located underneath the float. (c) Section view of the torsion balance showing the location of the damping coil and the damping disk attached to the float.
Schematic of the circuit that is used to provide both the restoring stiffness of the torsion balance and a method for applying servo torques.
Performance of the eddy current damper for currents in the range of .
Schematic of the capacitive sensor that is used to read out the position of the float.
Closed-loop gain-phase plot for the servo-control system. The ideal behavior, closed-loop and , is indicated as the dashed black lines. The effects of the measurement filtering are indicated by the dashed red lines.
A sketch of the circuit layout for the servo-control current source. The input summing amplifier allows higher resolution than what the digital-to-analog board can achieve with a single channel.
Plot showing the relationship between the stored current in the control coils and the reciprocal of the calibration fit parameter . There are two sets of data differing in the polarity of the stored current. The dashed line is included as a guide.
(a) Plot of the signal vs loss angle when the square wave is applied through an network. (b) Voltage spectral density of the oscillator output (upper plot) and capacitance sensor output (lower plot).
Article metrics loading...
Full text loading...