The relationship between field mirror, beam expander and galvanometer in laser marking machine
There are important optical devices such as field lens, beam expander and galvanometer in the optical path system of laser marking machine. What kind of relationship between them and the problems that need to be paid attention to during matching?
Field lens: The laser device mainly has a component called 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 complicatedly, it means that every point in a specified plane at its focal length is a lens that focuses. 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 spot of the galvanometer. If the entrance pupil of the field lens is smaller than the spot of the galvanometer, then it may appear. When marking to the edge of the field lens, the edge will be marked significantly shallower than the middle The position, even the range that can be reached will be smaller than the nominal range of the field lens.
Beam expander: When it comes to beam expanders, they are actually two lenses with different focal lengths. When laser equipment is used for long-distance illumination or projection, as well as focusing system-related aspects. An important part of the laser marking machine laser is called the laser beam expander, which plays an important role. The beam expander is an optical device that expands the laser beam. The product of the laser beam waist radius and the divergence angle is a fixed value. A laser beam passes through an X-fold beam expander. The beam waist radius is increased by X times, but the beam divergence angle is reduced to 1 / X. A laser beam with a small divergence angle will pass through a focusing lens of the same specification to obtain a smaller focusing point. As for the role of beam expanders, there are the following:
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 vibrating lens or mirror, and make the vibrating lens or 45-degree reflective lens more durable.
Third: Amplify the beam. This is mainly reflected in the laser performance system. Although we are in the industrial processing system, we amplify the beam every time, but our purpose is not only to amplify the beam but the first two purposes. The purpose of using a beam expander is to amplify the beam.
Galvanometer: In the final analysis, the galvanometer is two ammeters + pointers tied with X \ Y lenses, and the number of galvanometer spots (10 spots 12 spots 20 spots, etc.) means how much light can be reflected by the area of the galvanometer lens. 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 should pay attention to that the larger the lens of the galvanometer, the heavier the galvanometer lens. The larger the weight, the greater the inertia. The greater the inertia, the greater the inertia of our galvanometer. . Why choose big vibrating lens? This is because in order to obtain a beam with a smaller divergence angle, a large multiple beam expander is used, and a large multiple beam expander is used, then a large beam will inevitably come out. However, the line fineness and marking speed are a contradiction. We can only choose according to our needs, not both.