High Speed Imaging Spectropolarimeter for Dynamic Samples

Spectroscopic ellipsometry is recognized as the gold standard in noncontact characterization of the refractive index and thickness of a thin optical film or film stack on a substrate. However, it suffers from a number of shortcomings, perhaps the most important of which is the time required to perform a single measurement. Moreover, manufacturers are interested in comprehensive evaluation of thin films over a number of dimensional parameters including time, space, and wavelength, aspirations that cannot be achieved with existing devices. Polaris Sensor Technologies proposes to overcome these shortcomings through the design of an integrated spectroscopic polarimeter capable of performing measurements over all of these dimensions at high repetition rates. The proposed device integrates the established polarimetric architectures of division of aperture, focal plane, and time to yield multiplexed data collection method that simultaneously characterizes samples across all relevant dimensions. A unique sensor calibration procedure is proposed along with a strategy to apply this procedure for highly accurate thin film characterizations. This approach in conjunction with proposed dedicated data processing hardware, promises to overcome current ellipsometric limitations and open up the technique to larger application spaces, including the rapidly developing markets of thin film process control.