I started my Ph.D. 2023 at the University of Twente (UT) in The Netherlands. The project I am working on is called INSPEXT. During extreme ultra violet light (EUV) exposure, free standing thin films (pellicles) are physically and chemically degraded. The exact mechanisms are not yet known, thus this PhD project will investigate this phenomenon to gain an understanding into this. The focus of this project is specifically on in-situ EUV transmission measurements.