Single-shot focal spot image of EUV laser using a ZnO scintillator

Nakazato, Tomoharu*; Shimizu, Toshihiko*; Yamanoi, Kohei*; Takatori, Satoru*; Estacio, E.*; Cadatal, M.*; Sarukura, Nobuhiko*; Nishimura, Hiroaki*; Mima, Kunioki*; Tanaka, Momoko; Nishikino, Masaharu; Ochi, Yoshihiro; Oba, Toshiyuki; Kaihori, Takeshi; Kawachi, Tetsuya; Kagamitani, Yuji*; Ehrentraut, D.*; Fukuda, Tsuguo*

We have observed the single shot, focused image of a EUV laser through the emission of a ZnO scintillator. An estimated EUV laser focal spot size of 5088 micrometer is reasonable considering the long focal length of the spherical mirror. This work reports a feasible method to perform single-shot beam diagnostics for EUV laser sources using a ZnO crystal scintillator. Furthermore, since the ZnO fluorescence is at 380 nm wavelength, the imaging optics for the diagnostics can all be placed outside the vacuum chamber; thereby making experiments less cumbersome. Having a capability in fast and efficient beam profiling of EUV laser sources with acceptable resolving power is very important in future lithography applications.