The thickness and optical properties of thin films are critical to the performance and reliability of micro- and nanoelectronics devices. As features are constantly getting smaller, conventional methods cannot measure those properties on small structures. Imaging ellipsometry provides a fast and non-destructive method for characterizing surfaces and films on micron-scale structures, making it a valuable tool for materials research and development. This talk will show the principle and methods of imaging spectroscopic ellipsometry and some application examples.