Initially in the application of laser cutting, focusing mainly depends on manual. However, with the continuous development of laser technology, manual focusing will eventually be eliminated and replaced by automatic focusing. For example, a high-power laser cutting machine has a highly efficient fully automatic focusing function. However, some people will say that the optical path is integrated into the cutting head. Can't we simply change the height of the cutting head? When the cutting head rises, the focus position is high, and when the cutting head falls, the focus position is low. However, it turns out that this is not as simple as everyone thinks.

There is a nozzle at the bottom of the cutting head. During the cutting process, the distance (nozzle height) between the nozzle and the workpiece is about 0.5 to 1.5 mm, which can be regarded as a fixed value, so it is impossible to focus by lifting the laser head.

The focal length of a zoom lens is constant, so it is also unrealistic to focus by changing the focal length.

Changing the position of the focus lens will change the focus position accordingly: if the focus lens drops, the focus will drop; When the focus lens rises, the focus will rise. This is indeed a focusing method that uses a motor to drive the focusing mirror up and down, enabling automatic focusing

Another method of automatic focusing is to place a variable curvature mirror (or adjustable mirror) before the beam enters the focusing mirror, and change the divergence angle and focus position of the reflected beam by changing the curvature of the mirror.

With automatic focusing function, when processing workpieces of different materials and thicknesses, the machine can automatically and quickly adjust the focus to the appropriate position through numerical control. Therefore, it can significantly improve the processing efficiency of the laser cutting machine and greatly reduce the perforation time of thick plates.

Therefore, the automatic focusing function is an indispensable and important function of laser cutting machine tools.