How to adjust the focal length of the laser engraving machine? First of all, we need to know what the focal length is, that is, from the center of the convex lens to the point where the light rays converge into a point, then the distance between this is the focal length, the position of the focal length is the focal length, and the other is that the focal length of any convex lens is fixed Yes, the laser can only achieve the highest power and effect at the focal position. So if the position of the object B changes, the entire convex lens will also move relative to each other, this is to ensure that the focal point is always on the surface of B, and since we only use the focal point, it is not necessary to be so serious about the definition of focal length. Just make sure to use the same height value, you can use the two dotted lines that represent the focal length on the way. You can also find another location as a starting point. Well, after knowing what the focal length is, here we are. It is enough to adjust the lift of the convex lens. If it is a convex lens of a laser marking machine, it should be combined into a field lens and installed on the galvanometer.