Marking principle of Laser marking machine

Without the optical system, the Laser marking machine can not work normally. According to the different working modes of Laser marking machine, there are various optical systems, including beam expander (to make the diameter of laser beam larger and reduce the divergence angle of laser beam), optical focusing lens (to make the diameter of laser spot acting on the workpiece surface smaller as far as possible) and reflector (to change the direction of laser beam). The light energy emitted by a 70W CW laser is similar to that emitted by a 70W ordinary bulb. Ordinary light bulb is designed to be used for lighting. The light it emits is radiated in all directions. Different from light bulb, the light emitted by laser is concentrated in a small range. Therefore, the energy density of the laser (energy per unit area) is far greater than that of the bulb. The actual marking effect depends on the energy density of the workpiece surface, not the laser power. In order to do laser marking well, we must further improve the laser energy density. There are two ways: one is to increase the laser output power, which is difficult or not worth the loss in general; Another method is to further refine the laser beam emitted by the laser, which requires an optical system. It's very simple to make the laser beam thinner. Only a focusing lens is needed to focus the laser beam to a very small point. The laser produced by the laser is not an ideal parallel light, it has a very small divergence angle, which will affect the focusing effect of the focusing lens. Therefore, before the focusing lens, there should be a beam expander to reduce the divergence angle of the beam. The beam expander can not only reduce the divergence angle of the beam, but also enlarge the diameter of the laser output beam. We know that the size of the focused spot depends on the diameter of the incident beam and the focal length of the focusing lens: the larger the diameter of the incident beam, the smaller the diameter of the focused spot. The increase of the incident beam diameter can also reduce the laser energy density on the mirror which changes the direction of the laser beam in the laser optical path, and ensure that the mirror will not be burned by the laser beam when it works for a long time.

 

Static marking

One is that the laser beam is fixed and the workpiece moves. The other is to control the speed of light through the galvanometer to achieve marking.

Flight marking

When the workpiece moves, the marking machine uses the encoder to collect the motion signal, or uses the simulation speed to change the character shape through the software to realize the normal marking in the process of movement