We report the design of a novel laser line-triangulation laryngoscope for the quantitative visualization of the three-dimensional movements of human vocal folds during phonation. This is the first successful in vivo recording of the three-dimensional movements of human vocal folds in absolute values. Triangulation images of the vocal folds are recorded at the rate of with a resolution of . A special image-processing algorithm is developed to precisely follow the subpixel movements of the laser line image. Vibration profiles in both horizontal and vertical directions are calibrated and measured in absolute SI units with a resolution of . We also present a movie showing the vocal folds dynamics in vertical cross section.