Imaging spectroscopic ellipsometry involves combining the sensitivity of ellipsometry to detect changes in film thickness and optical properties with the imaging capabilities of optical microscopy. This unique combination enables thin film metrology as well as the determination of optical properties at the microscopic scale. Lead-halide perovskite solar cells are very promising from a performance point of view in the fields of photovoltaics, optoelectronics, light-emitting diodes, lasers, and photodetectors. Most of these applications require a deep understanding of the optical properties of the material. It is important to note that the grain size must be related to the optical properties, as the film may contain crystalline and amorphous portions depending on the crystallization method. A critical aspect is stability against environmental influences. One focus of the webinar will be on the extraction of clear spectra from samples with local layer thickness variations, and another will be the assessment of material stability at the microscopic scale by comparing Delta and Psi micro-maps at variable wavelengths. The webinar will be completed with a demonstration of the instrument highlighting the new sweep mode—a game changer in ellipsometry?