Method for generating and measuring the micro-Newton level forces

A method for generating and measuring the micro-Newton level forces is proposed. In the method, the force is generated and measured as the inertial force acting on a mass. A pneumatic linear bearing is used to realize a linear motion with sufficiently small friction acting on the mass, i.e. the moving part of the linear bearing. The inertial force acting on the mass is calculated from the velocity of the mass, and the velocity is determined highly accurately by means of measuring the Doppler shift frequency of the laser light beam reflecting on the mass using an optical interferometer. To demonstrate the performance of the method, the mechanical properties of a piece of paper have determined with the resolution of 0.5 μN.