Auto-focus function of laser cutter-one of the advantages of laser cutting is that the energy density of the beam is high. So the diameter of the focal spot will as small as possible to produce a tiny slit. Because the smaller the focal depth of the focusing lens, the smaller the diameter of the focal spot. For high-quality, high-precision cutting, the effective focal depth is also relate with the lens diameter and the material being cut. So it is very important to control the focus and the position of the surface of the cutting material.

So what is focus control? When cutting different thickness plates, to show the perfect cutting effect, the focus of the laser beam will set in different places. This is called focusing.

Auto-focus function of laser cutter

In the early days of laser cutting applications, we rely on manual focusing. However, with the development of laser technology, manual focusing will eventually be eliminating, and automatic focusing functions will be more and more popular. For example, high-performance high-speedlaser cutting machines have automatic focusing functions. So, some people will say that the light path is integrated into the cutting head. Is it not easy to change the laser height? When the cutting head is raising, the focus position is high, and when the cutting head is lowering down, the focus position is low. However, it turns out that it is not as simple as everyone thinks.

The bottom of the cutting head is a nozzle. During the cutting process, the distance between the nozzle and the workpiece (nozzle height) is about 0.5 to 1.5 mm.  Therefore, the focus is not adjustable by lifting the laser head.

The focal length of the focusing lens is unchangeable, so it is not realistic to adjust the focus by changing the focal length. If the position of the focusing lens changed, the focus position also changed accordingly. The focus lens goes down, the focus goes down, and the focus lens goes up, the focus goes up. It uses a motor  to driving the focusing lens for up and down movements to achieve automatic focusing.

Another method of automatic focusing

Before the light beam enters the focusing mirror, a variable curvature mirror (or tunable mirror) set. By changing the curvature of the mirror, the divergence angle of the reflected beam changed, and the focus position changed.

With automatic focus function, the machine tool can automatically adjust the focus to the appropriate position through CNC. When processing workpieces of different materials and thicknesses. This can significantly improve the processing efficiency of the laser cutting machine. And the punching time of thick plates will reduce greatly. Therefore, for high-speed laser cutter tools, the automatic focusing function is important and indispensable.

All XT laser cutting machines  have automatic focusing laser heads. The same laser head can quickly change focusing lenses with different focal lengths, adapt to various power processing, and meet the cutting of different thickness plates. By using the auto-focus function, users can finish cutting or engraving quickly and accurately. So it makes the cutting or engraving work more time-saving and improves the user’s work efficiency.