The basic optical principles of handheld welding heads include three parts: beam collimation, beam oscillation, and beam focusing, as shown in the following figure. After the laser beam is emitted from QBH, it becomes parallel light through the collimator, and then reflects back to the focusing mirror through the galvanometer, finally focusing on the surface of the workpiece.
Beam collimation
The light coming out of the optical fiber of QBH is a point light source with a certain divergence angle. During propagation, it will spread out in a conical shape to the front, such as turning on a flashlight or lighting a match in the dark.
The function of a collimator is to transform this divergent beam of light into parallel light, allowing it to propagate along a straight line without deviation; Simultaneously control the waist radius of the beam to limit it to a narrow welding head path.
Beam oscillation
In handheld welding, the purpose of beam swinging is to improve the adaptability of weld seam gaps. Due to the fact that the focused light spot is a very small spot, it is difficult to ensure walking along the trajectory of the weld seam when held in hand. On the other hand, it is also difficult to cover the weld seam with large gaps. By arranging the beam in a straight line as wide as 3.0mm, it is easy for operators to align and cover the laser onto the weld seam.
Its implementation method is to deflect the vibrating lens back and forth at high speed under the drive of the motor, thereby achieving the goal of changing the path of the laser beam.
The basic principle is shown in the following figure: according to the basic reflection law, the reflection angle is equal to the incident angle. When the galvanometer is at angle 1, the light reflects along path 1 and focuses on point 1; When the galvanometer is at angle 2, the light reflects along path 2 and focuses on point 2.
If the galvanometer is deflected back and forth between the angles 1 and 2, the focus point will move between the two points. When the speed of movement is fast enough, it can be regarded as a straight line, and the length of this straight line is called the "swing width", and the speed of deflection is called the "swing frequency".
Our Guanghui Laser intelligent air-cooled handheld welding machine has an adjustable swing width of 0-5mm and an adjustable swing frequency of 0-300Hz.
Beam focusing
What is reflected from the galvanometer is a beam of parallel light, which converges into a small spot after passing through the focusing mirror and finally enters the surface of the workpiece.
The function of a focusing mirror is to concentrate parallel beams of light together, forming a very small spot of light, thereby generating an ultra strong energy density.
The role of protective lenses
During the welding process, handheld welding can generate a certain amount of smoke and dust, which may damage the focusing lens. Therefore, it is necessary to protect the lens to provide insulation and protection.
