Karl Ferdinand Braun

German physicist (1850 to 1918) who built the first cathode-ray oscilloscope, the Braun tube, in 1897, producing a narrow, steerable electron beam that traced patterns on a fluorescent screen; the device became the forerunner of the television tube and radarscope. He shared the 1909 Nobel Prize in Physics with Guglielmo Marconi for contributions to the development of wireless telegraphy.