Laser triangulation is used to examine the vertical (longitudinal) movements of the vocal folds during phonation. A method for evaluating the blurry, elongated image of the laser spot by vibration amplitude is presented. The method is used in situ on humans and is calibrated with known vibrations of bovine tissue.
"Measurment of human vocal fold vibrations with laser triangulation," Optical Engineering 40(9), (1 September 2001). http://dx.doi.org/10.1117/1.1396324