Spraying and coating technologies are gradually being emphasized as a promising method for fabrication of thin film. Greater comprehension about the properties of thin film in qualitative manner is intensively required to satisfy the needs of production process. Therefore, ensuring thin film quality through an on-line, real-time, monitoring system has been and remains a major challenge and goal. The objective of this paper is to develop a monitoring system to handle the automated in-process inspection of thin film. The developed inspection system is based on the use of an ultra fast Ti: Sapphire laser with pulse duration of less than 100 fem to second. A differential time-domain spectroscopy is employed to determine the refractive index. The capability of measuring the dielectric constant is experimentally demonstrated. The results indicate that the system is able to simultaneously determine the index of refraction and the dielectric constant for thin film. Also, it has sufficient sensitivity to perform these measurements on thin film.
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