Ludwig Louis Albert Zehnder (4 May 1854, in Illnau – 24 March 1949, in Oberhofen am Thunersee) was a Swiss physicist, one of the inventors of the Mach–Zehnder interferometer. Zehnder was a student of Wilhelm Röntgen, professor of physics at the universities of Freiburg and Basel. He produced the first pictures of the human skeleton by shining x-rays through the human body. 1854 births 1949 deaths Swiss physicists Optical physicists Illnau-Effretikon People from Pfäffikon District