Handheld laser welding machine is an epoch-making star product in the laser application market in recent years, and it has rapidly emerged as one of the growth points of the green laser industry. Since 2018, the annual compound growth of laser hand-held welding has exceeded 100%, and it is expected to reach 500 integrated manufacturers of various types of hand-held laser equipment in 2021, showing explosive growth. For handheld laser welding equipment, the welding head that connects to the use scene and outputs laser energy is an extremely important component. In the welding head, the optical part is a very important part.

The basic optical principle of the handheld welding head includes three parts: beam collimation, beam swing, and beam focus, as shown in the figure below. After the laser beam is emitted by the QBH, it becomes parallel light through the collimator, and then is reflected by the galvanometer to the focusing mirror, and finally focused on the surface of the workpiece.

Beam collimation

The light coming out of the QBH fiber is a point light source with a certain divergence angle. During the propagation process, it will spread out in a conical shape, such as turning on a flashlight or lighting a match in the dark.

The function of the collimator lens is to turn this divergent light into parallel light so that it can travel in a straight line without deviation; at the same time, it controls the beam waist radius of the beam and restricts it to the narrow beam path of the welding head.

Beam swing

In handheld welding, the purpose of beam swing is to improve the adaptability of the weld gap. Since the focused light spot is a small light spot, it is difficult to ensure that it walks along the weld track while holding it. On the other hand, it is also difficult to cover the weld with a large gap. By placing the beam into a straight line as wide as 3.0mm, it is convenient for the operator to align the laser and cover the weld.

Its realization is that the vibrating lens deflects back and forth at a high speed under the drive of a motor, so as to achieve the purpose of changing the path of the laser beam.

The basic principle is shown in the figure below: According to the basic law of reflection, the angle of reflection is equal to the angle of incidence. When the galvanometer is at the No. 1 angle, the light is reflected along the No. 1 path and focused to the No. 1 point; when the galvanometer is at the No. 2 angle, the light is reflected along the No. 2 path and is focused to the No. 2 point.

If the galvanometer is deflected back and forth between the angles of 1, 2, and the focused light spot will move between the 1, 2 points. When the moving speed is fast enough, it can be regarded as a straight line. The length of this straight line is called It is the "swing width", and the deflection speed is called the "swing frequency".

Beam focus

What is reflected from the galvanometer is a beam of parallel light, which is condensed into a small spot after passing through the focusing lens, and finally incident on the surface of the workpiece. The function of the focusing lens is to concentrate the parallel beams together to form a small spot, thereby generating a super energy density.

Protect the lens

Hand-held welding will produce a certain amount of smoke and dust during the welding process, which may damage the focusing lens, so a protective lens is needed to protect it.

The protective lens is a consumable item, and it is necessary to check whether it is in good condition every certain time. The use period is determined according to the intensity of use and the scene of the equipment.