3. Confocal Microscopy for Surface Profilometry

The application of automated optical inspection (AOI) to advanced manufacturing processes with tight takt time and specifications is critical in winning today’s global competition. In the past decades, great effort had been devoted to developing novel solutions for in-line optical inspection of surfaces and the dynamic characteristics of tested components or devices. Conventional approaches to microscale 3D surface profilometry have adopted novel optics or concepts in confocal microscopy for measuring 3D surface characteristics with high speed and precision. One-shot measurement capability is demanded to minimize measured uncertainty from environmental vibration or system instability. Nevertheless, extremely high-speed microscopic 3D confocal profilometric methodologies for 100% full-field inspection are yet to be developed. This chapter intends to provide the measurement principle and development of confocal optical profilometry in overcoming bottlenecks and developing feasible solutions for novel manufacturing technologies, such as roll-to-roll nanoimprinting or semiconductor processes. It contains the basic optics, the measuring algorithms and industrial applications in optical confocal microscopy required for surface profilometry.