| 摘要 |
A device for focusing a laser beam (1) onto the surface (4) of a liquid, viscous or powder material, of which the level is variable over time, comprising: an image processing system for determining the apparent internal diameter of the nozzle (3) at the surface (4) and means for successively calculating the distance between the laser source (1) and the surface (4) on the basis of the apparent internal diameter of the nozzle (3) and the focusing that results therefrom of the laser beam on the surface (4); means (6, 7, 12) for modifying the focus of the laser beam by acting on optical means (2) on the basis of said calculated distance. |
