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A Brief Introduction to Fiber Lens

A Brief Introduction to Fiber Lens

Wenting Wang |


In the fiber laser marking machine, the fiber lens is one of the most important parts. It allows you to see the glass fiber end clearly so that you can mark it according to your needs. You do not have to be an expert in fiber lenses. However, there are many questions you should consider before making your final decision.


Structure of fiber marking machine

The fiber laser engraver is mainly composed of a 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 Monport fiber laser engraver 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 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 sound and its service life is long. 

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-theta scanning lens, also known as a lens, lens, field lens, objective lens, etc., mainly plays a focusing role in laser marking machines, laser coding machines, laser engraving machines, and other equipment. 

Different f- theta lenses have different focal lengths, and the marking effects and ranges are also different. Monport fiber laser marking machine uses a high-performance focusing system. The standard lens focal length is f = 160mm, and the effective scanning range is 110mm. Users can choose different types of lenses according to their needs. 

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 lengths and narrow working engraving areas, which does not allow you to engrave large products and prevent you from using different applications. 


Can you use a different size fiber lens?

Monport provides different three-size fiber lenses for laser engravers to choose. 

Focal length must be considered when selecting fiber lasers. 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 fiber laser power supply usually brings a 300mmx300mm lens; This machine can mark 200mmX200mm deep and clear the best working area. However, the machine can also use a 500mmx500mm lens. What happens when using a 500mm 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 a 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 working engraving area its the one we need to decide which 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 focal point of the light. 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.


What can fiber 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 the 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, then 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.


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.

Focal spot diameter: for a scanning system with incident laser beam diameter D, field lens focal length f a,nd 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.



There are many choices of fiber lenses out there, and they can have a large impact on your design production. They increase your manufacturing speed, and the right one can improve the quality of your marks. If you're looking to get started with fiber lenses, or are looking for a new lens to replace an old, damaged one, be sure to keep these suggestions in mind.


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