What nationality was the scientist who developed the Wein filter ?
Wien filter:  It is named for Wilhelm Wien who developed it in 1898 for the study of anode rays. Wilhelm Wien: Wilhelm Carl Werner Otto Fritz Franz Wien (] ; 13 January 1864 – 30 August 1928) was a German physicist who, in 1893, used theories about heat and electromagnetism to deduce Wien's displacement law, which calculates the emission of a blackbody at any temperature from the emission at any one reference temperature.
German