Development of nanonewton force standard based on a torsion pendulum

This paper introduces the torsion pendulum experiment at center for measurement standards, industrial technology research institute (CMS/ITRI). The torsion pendulum experiment aims at SI traceable measurement and generation of force at nano/subnano-newton scale. Three force generation mechanisms, namely optical force, electrostatic force and universal gravitation are implemented in the experiment. Recent progress on gravitation measurement is reported in this article.