Nanonewton force generation and detection based on a sensitive torsion pendulum

TL;DR

This paper presents a sensitive torsion pendulum experiment for measuring and calibrating nanonewton forces using gravitational, optical, and electrostatic forces, with recent results on radiation pressure and capacitive sensing.

Contribution

It introduces a novel torsion pendulum setup for nanonewton force calibration using multiple force mechanisms and detailed design of sensing and actuation units.

Findings

Radiation pressure measurements achieved.

Capacitive displacement sensing designed.

Force calibration using gravitational attraction.

Abstract

In this paper, we introduce the experiment based on a sensitive torsion pendulum for measuring and calibrating small forces at nanonewton scale. The force standard for calibration is the universal gravitation between four masses separated by known distances. It is realized by two test masses suspended as the part of torsion pendulum and two source masses on a rotation table. Two force generation mechanisms, optical force from radiation pressure and electrostatic force by capacitive actuation unit, are designed and will be calibrated by the gravitation force. We present our recent results of radiation pressure measurements, and describe the design of capacitive displacement sensing/actuating unit.