Activation of micro gears using a laser diode system

It is a well-known phenomenon that light carries momentum. This property has led to the insertion of MOEMS (Micro-Optical-Electro-Mechanical Systems) into the designs of optical systems. MOEMS represent a significant size reduction for optical components. In this thesis, the light activation of one of these system components is investigated. Micron-sized gear structures made from polysilicon are anchored to a Silicon substrate with posts that are capped so that the gears cannot slip off. Radiation pressure from a laser diode is used to rotate the gears. Equations for force and torque are determined as well as the equation of motion for the light activation technique. Computer modelling is used to determine theoretical results for the motion of the gears when subjected to radiation pressure. An experimental set up that was used to investigate the gears' behaviour is then described. Experimental measurements are described and results are used to establish a relationship between the applied rotational torque and the resulting angular velocity for gear samples. The average damping constant for these gear assemblies is then calculated and compared to accepted values for the micron-scale devices. In addition, the minimum torque necessary for rotation is determined and the effects of surface coatings on the gear's rotation are also outlined.