One could tune an FEL to precisely the same wavelength as ASML’s setup if one were so inclined. (Subject to all kinds of complications, as the high energy elect

One could tune an FEL to precisely the same wavelength as ASML’s setup if one were so inclined. (Subject to all kinds of complications, as the high energy electron sources needed are complex and EUV light is hard to work with. But there isn’t much of a fundamental constraint on the ability to adjust the wavelength of a FEL.)