An installation for spectroscopic measurement includes a focusing system (2) for focusing a laser beam (3) on a sample (4) for analysis and a system (17) for collecting and spectroscopically analyzing light rays emitted by the plasma (15), this system (17) including, in particular, an optical fiber (18) for collecting light. The installation also includes a motor-driven system (23) for moving the optical fiber (18), an optical imaging system (25) for imaging the plasma in the form of an image, and a processor and control unit (24). The unit (24) is capable of analyzing the image formed by the optical imaging system in order to select a zone of interest and controlling the motor-driven system (23) in order to place the optical fiber in a position enabling it to collect light coming from the selected zone of interest in the plasma.