| The purpose of this study is to implement and evaluate the non-destructive and non-invasive acoustic monitoring systems for improving the quality assurance and process control in various industrial processes, such as semiconductor fabrication and pharmaceutical manufacturing.; Material characterization can be affected at any stage due to the complex uncertainties in fabrication/manufacturing systems. Monitoring the variations in material properties in a non-invasive and non-destructive manner is of both practical and scientific interests, and correspondingly initiated the motivation of this current research. Acoustic waves, which are highly related to the material properties and physical changes of a structure, are generated and detected through various ultrasonic techniques. For instance, a novel air-coupled excitation with interferometric sensing technique was proposed for monitoring small-scaled structure of dimensions from millimeter ranges to nanoscales.; Advanced signal processing methodologies are then implemented and applied on the acquired acoustic waveforms to extract features which demonstrate the mechanical or geometric changes of the tested specimen during its normal service throughout the fabrication process or in-process of the batch manufacturing operation. |
