The relationship between field mirror, beam expander and galvanometer in laser marking machine
There are important optical devices such as field mirror, beam expander and galvanometer in the optical path system of laser marking machine. What kind of relationship exists between them and the problems that need to be paid attention to in matching, let's take you to understand:
Field lens: The laser equipment mainly has a component called the field lens. It is to determine the scope of laser work of the laser marking machine. It is mainly used to focus the light from the galvanometer on a plane. To put it simply, it is a focusing lens. To put it more complex, it is a lens in which every point in a specified plane of its focal length is a focusing point. The field lens has a parameter called the entrance pupil, also called the entrance pupil. For the entrance pupil, we require that the entrance pupil of the field lens ≥ the light spot of the galvanometer. If the entrance pupil of the field lens is smaller than the light spot of the galvanometer, it may occur. When marking the edge of the field lens, the edge will be marked significantly lighter than the middle. position, and even the range that can be hit will be smaller than the nominal range of the field lens.
Beam Expander: Speaking of beam expander, it is actually two lenses with different focal lengths. When laser equipment is used for long-distance illumination or projection, and related aspects of focusing systems. An important part of the laser of the laser marking machine is called the laser beam expander, which plays a very important role. A beam expander is an optical device that expands the laser beam. The product of the beam waist radius and the divergence angle of the laser is a constant value. When a laser beam passes through an X-fold beam expander, its beam waist radius is increased by X times, but the beam divergence angle is reduced to 1/X of the original. A laser beam with a small divergence angle will obtain a smaller focus point after passing through a focusing mirror of the same specification. As for the role of the beam expander, there are the following points:
First: make the focusing effect better and get a smaller focusing spot. The light from the beam expander with a larger multiple is better focused by the focusing lens.
Second: Disperse the energy evenly, reduce the energy density reaching the galvanometer or reflector, and make the galvanometer or 45-degree reflector more durable.
Third: Amplify the beam, which is mainly reflected in the laser show system. Although we amplify the beam every time in the industrial processing system, our purpose is not only to amplify the beam but the first two purposes. In the laser show system The purpose of using a beam expander is to amplify the beam.
Galvanometer: In the final analysis, the galvanometer is two ammeters + pointers tied to X\Y lenses, and the number of galvanometer spots we are talking about (10 spots, 12 spots, 20 spots, etc.) means how much light the area of the galvanometer can reflect. The smaller the galvanometer lens, the smaller the beam that can be reflected; the larger the galvanometer lens, the larger the beam that can be reflected. But we have to pay attention that the larger the lens of the galvanometer, the greater the weight of the galvanometer lens. When something with a heavier weight moves, the inertia will be greater, and the greater the inertia, the speed of our galvanometer will inevitably be slower . Why choose a large vibration lens? It is because in order to obtain a beam with a smaller divergence angle, a large-power beam expander will be used, and if a large-power beam expander is used, a large beam will inevitably come out, and the large beam must be reflected by a corresponding galvanometer. However, line fineness and marking speed are a contradiction, we can only choose according to our needs, and we cannot seek the best of both.
