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A Brief Introduction to Fiber Lens

A Brief Introduction to Fiber Lens

First of all, we should understand the main composition of a marking machine. The so-called fiber laser marking machine means that the marking machine uses a fiber laser. The fiber laser has the characteristics of small volume (no water cooling device, air cooling), good beam quality (basic mode), and maintenance free.

Structure of fiber marking machine

It is mainly composed of laser, galvo lens and marking card. The laser marking machine produced by fiber laser has good beam quality, its output center is 1064nm, and the service life of the whole machine is about 100000 hours. Compared with other types of laser marking machines, the service life of the machine is longer, and the electro-optical conversion efficiency is more than 28%. Compared with other types of laser marking machines, the conversion efficiency is 2% - 10%. It has great advantages in energy conservation and environmental protection. This means that the working area of some machines, such as all-in-one machines, cannot exceed 10x10cm, because the head needs a focus space between the lens and the workbench.

Laser

This is the core part of the laser marking machine. According to different models, it usually has many series of lasers: optical fiber, ultraviolet, CO2, YAG, semiconductor, etc. Its output laser mode is good and its service life is long. It is designed to be installed in the marking machine casing.

Laser power supply

The laser power supply of the laser marking machine is a device that provides power for the laser, and its input voltage is AC 220V. It is installed in the control box of the marking machine.

Galvanometer field mirror scanning system

Galvanometer scanning system is composed of optical scanner and servo control. Composition of vibrating lens: it is composed of stator, rotor and detection sensor. The whole system is designed and manufactured with new technologies, new materials, new processes and new working principles.

The optical scanner uses a servo motor with a dynamic magnetic deflection working mode. The optical scanner is divided into an X-direction scanning system and a Y-direction scanning system. A laser reflection lens is fixed on each servo motor axis. Each servo motor is controlled by a digital signal sent by a computer.

Computer control system

The computer control system is the control and command center of the whole laser marking machine, and also the carrier of software installation. Through the coordinated control of the acoustooptic modulation system and the galvanometer scanning system, the marking process of the workpiece is completed.

Focusing system

The function of the focusing system is to focus parallel laser beams at one point. F is mainly used- θ Lens, different f- θ The focal length of the lens is different, and the marking effect and range are also different. The optical fiber laser marking machine uses an imported high-performance focusing system. The standard lens focal length is f = 160mm, and the effective scanning range is Φ 110mm。 Users can choose different types of lenses according to their needs. seven

Marking control software

The laser etching machine software is used to control the marking parameters, control the debugging application interface, and operate all the marking actions.

This means that you should check well which machine model you will choose, because some models have very narrow focal length and narrow working engraving area, which does not allow you to engrave large products and prevent you from using different applications. If you want to choose a suitable workspace for your app, please contact us.

Focal length must be considered when selecting fiber laser. The focal length is determined by two variables. The first variable is the power of the (power supply) and the second variable is the working area of the lens. These must be combined correctly to achieve depth and accurate engraving. For example, a 50W power supply usually brings a 30x30cm lens; This machine can carve 20cmX20cm deep and clear best working area. However, the machine can also use a 50x50 lens. What happens when using a 50cm lens and a 50W power supply? The answer is that the engraving intensity in the working area is much weaker and the depth is much smaller, resulting in power loss of the machine and laser dissipation. Similarly, when choosing an engraving machine, you should consider power and lens. If you are looking for a low-power laser with a large engraving area, please ensure that your engraving effect is very weak and shallow.

Before buying a laser engraving machine, it is essential to know which it is the working engraving area its the one we need to decide which its the power source we can use.  The fiber optic laser head works like a magnifying glass, and the closer the object is, the more diffuse its the focus point of the light.

Also, on the contrary, if the Magnifying glass is far away, the light is scattered, and it also fails to engrave clearly and powerfully.

The lens is selected according to the laser wavelength and marking range. The larger the marking format, the longer the focal length, the larger the focus spot, and the greater the distortion. The laser spot is not delicate enough, and the smaller the power and energy density of the laser single point.

F-theta scanning lens, also known as lens, lens, field lens, objective lens, etc., mainly plays a focusing role in laser marking machine, laser coding machine, laser engraving machine, laser engraving machine and other equipment. Its shape is as follows:

The following is the working principle of the conventional laser marking machine (laser engraving machine, laser coding machine, laser lettering machine, etc.), as follows:

What can the lens do for you?

In recent years, laser marking technology has become one of the largest application fields of laser processing. Its characteristics of high marking speed, clear writing, strong anti-counterfeiting function and low pollution have attracted widespread attention in the industry. And works near the focal plane of the objective lens. This lens is called F- θ Lens.

In the marking system, the laser beam passes through F θ Lens system and will produce off-axis deflection. An abnormal image or distortion will appear on the mark surface with respect to the ideal plane. In brief, the laser beam is irradiated by F θ The lens scatters to form a relatively fixed focal length and mark range. For example, our usual laser marking range is 100mm x 100mm. If you want to mark a wider range of content, you need to replace the f-theta lens with a wider range of marks.

Different types of galvanometer

F- θ The lens is more expensive because it is processed so that the light beam will try to be perpendicular to the workpiece and the focus is almost the same throughout the process field. However, for non critical tolerances, the actual "laser mark" position and focus are more predictable.

Not f- θ The lens is cheaper, and when the light beam leaves the lens, the light beam is similar to a pendulum, so changes in the focus away from the field center should be expected. In addition, due to different focal points, the laser mark position will shift.

What are the different effects of lenses?

Because the laser output energy is constant, when you replace a wider range of lenses, the output laser energy will be reduced. Because the laser energy is scattered, we usually recommend that customers choose high output power laser marking machines, such as 30W, 50W and 60W, to adapt to the larger marking area F θ Lens.

How to replace f- θ What should I do after changing the lens? It is very easy to replace the field mirror, but we still have a lot of work to do after replacement. We need to adjust the focal length of the laser head, adjust the accuracy of the marking area of the laser head, and then adjust the position of the red light positioning offset.

 

How to choose the right lens according to your needs?

When designing a lens, the main technical parameters to be considered are the working wavelength of the laser, the incident pupil, the scanning range and the diameter of the focused spot.

Working wavelength: mainly depends on the wavelength of the laser. The lens is coated at a given laser wavelength. If the lens is not used within the given wavelength range, it will be burned by the laser. Under normal conditions, the operating wavelength of the fiber laser is 1064nm.

Entrance pupil: if a single lens is used, the reflector is placed at the entrance pupil, and the diameter of the maximum available beam is equal to the diameter of the entrance pupil.

Scanning range (marking range): the larger the scanning range of the field mirror, the more users like it. However, if the scanning range is increased, the focus becomes larger, and the distortion also increases. In addition, in order to increase the scanning range, f θ Lens focal length and working distance. The working distance is long, which inevitably leads to the loss of laser energy.

Another focus diameter is proportional to the focal length, which means that with the increase of the scanning range, the spot with the increase of the focus diameter is not fine enough, and the laser power density decreases very fast, which is not conducive to processing. Therefore, it is not that the larger the marker range, the more f θ The better the lens is, but it needs to be selected according to needs.

Focal spot diameter: for a scanning system with incident laser beam diameter D, field lens focal length f and beam quality factor Q, focal spot diameter d = 13.5qf/d (mm). Therefore, a beam expander can be used to obtain a smaller focused spot.

The approximate spot size of each laser lens is shown below. The lens acts as a magnifying glass to converge the light beam. The sharpest convergence point is the "spot size" and the position where laser processing occurs. There is always a trade-off between shots. Using a larger lens with a larger light spot may mean using a lower DPI and completing the work faster; However, if you are looking for details, whether it is vector cutting or raster engraving, then you may find that smaller lenses with higher resolution are better, but use higher DPI.

Next article Engraving Metal with a Fiber Laser

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