Austrian physicist who in 1842 described the Doppler effect, 多普勒效应: a wave's pitch rises as its source comes closer and falls as it moves away. Weather radar and ultrasound scans use it.
多普勒 is chosen for sound alone, 多 do + 普 pp + 勒 ler, and Taiwan writes it 都卜勒. Doppler radar is 多普勒雷达, but a hospital Doppler scan is usually just 彩超, 'colour ultrasound', for the coloured blood flow on screen.