1. Mark a certain range of content with partial focus
Since each focusing mirror has a corresponding focal depth range, when the out-of-focus method easily leads to a large-scale marking pattern, the edge is at the critical point of the focal depth or exceeds the focal depth range, so it is more likely to cause unevenness of the effect. Therefore, the laser energy must be considered.
2. The laser output spot is blocked, that is, the laser beam lacks the spot behind the vibrating mirror and the scene mirror, and is not round enough.
The laser output head, fixing fixture, and vibrating mirror are not adjusted, which causes part of the light spot to be blocked by the vibrating mirror. After being focused by the field lens, the light on the frequency doubling film is not circular, which may also cause uneven effects.
Another situation is that the vibrating mirror deflection mirror is damaged, and when the laser beam passes through the damaged area of the mirror, it does not reflect well. Therefore, the laser energy of the laser beam passing through the damaged area of the lens is inconsistent with that of the non-damaged area of the lens, and the final laser energy acting on the material is different, making the marking effect uneven.
3. Thermal Lens Phenomenon
As the laser passes through the optical lens (refracted, reflected), the heat of the lens creates a subtle deformation. This deformation increases the focal point of the laser focus and shortens the focal length. If the machine is fixed and the distance is adjusted to the focus, after the laser is turned on for a period of time, the laser energy density acting on the material will change, resulting in uneven marking effect.
4. The level of the machine is not adjusted, that is, the laser vibration lens or the scene lens is not parallel to the processing table.
Since the two are not horizontal, the distance of the laser beam through the mirror to the processing object is inconsistent. Finally, the energy of the laser falling on the object to be processed will have an inconsistent energy density, thus exhibiting a non-uniform effect on the material.
5. Material reasons, such as inconsistent film thickness on the material surface or changes in physical and chemical properties.
Materials are sensitive to laser energy. Usually under the same material, the laser energy reaches a certain damage threshold of the material. When the thickness of the material coating is different or other physical and chemical treatment processes are uneven, the effect after laser marking will also be uneven.
