Recently, fiber laser technologies have become increasingly popular because of their high precision, efficiency and versatility. A focusing lens is an important part of fiber laser systems, and it plays a crucial role in determining the quality and accuracy of laser beam. The right focusing lens will affect your machine performance like cutting speed, accuracy and overall effects.
I. What is Focusing Lens?
The focusing lens focuses laser beam emitted by fiber laser generator onto materials, which can concentrate laser into a small but precise spot. The lens can focus the divergent laser beam to a high-intensity point, so as to enhance laser density and make the laser cut, weld, or mark materials at fast speed.
As for fiber laser systems, focusing lens is typically made from quality optical materials like ZnSe (Zinc Selenide), CaF2 (Calcium Fluoride) or GAs (Gallium Arsenide), which usually offer superior laser transmission properties. These materials are designed to withstand high-power laser beam.
II. Importance of Focusing Lens
The focusing lens plays a key role while determining the performance of fiber laser systems for several reasons below:
Laser beam focus
Its primary function is to concentrate laser beam onto materials. A well-focused beam will give a small spot that offers precise operation. Otherwise, an unfocused beam may cause excessive heat, material distortion or low-quality work.
Precision and accuracy
Fiber laser is used for fields that have high demands on speed and precision, incl. electronics, medical device and aerospace. A proper focusing lens helps achieve the specific level of accuracy required.
Working efficiency
The focus quality decides how fast the laser cuts through materials. A properly focused beam is accompanied by the faster speed and cleaner effects, in this way, raising overall productivity.
Material compatibility
Different materials need different focal lengths and lens configurations. The correct lens can convey optimal energy to the workpiece, so as to minimize damage or wastage and improve the quality of final products.
III. Key Factors to Consider When Choosing Focusing Lens
Choosing a proper focusing lens for your fiber laser is related to several factors. Here’s a guide to help you make an informed decision:
1. Focal length
Short focal length (100mm)
These lenses create a small, highly-concentrated laser spot and are suitable for precise, fine cutting of thinner materials. They also offer better edge quality but may struggle with the thicker materials.
Long focal length (200mm, 300mm)
Long focal length creates a large spot, which takes effect when cutting thicker materials or when irregular workpiece is handled. These lenses are fit for fields requiring deep penetration, such as welding or cutting thicker metals.
2. Lens material
ZnSe
Known for its excellent optical properties, ZnSe is used in CO2 and low-power fiber laser generators. It is featured by high thermal stability and transmission but may not be fit for high-power lasers because of its susceptibility to thermal expansion and degradation.
CaF2
With exceptional optical transmission, resistance to thermal distortion and low absorption rate, CaF2 lenses can be used for high-power fiber lasers. They can cope with the higher power and keep high performance for a long time.
SiO2
This material is frequently applied to the higher-power lasers thanks to its robustness and resistance to heat. It is less used for fiber lasers but is found in some professional laser cutting systems.
GAs
GAs lenses can meet the high demands for the highest quality of beam focus and clarity. The lenses provide excellent laser transmission and focus control, especially in sectors requiring high precision.
3. Lens diameter
The diameter of focusing lens affects how much of laser beam can pass through it before being focused. A lens at larger diameter can collect more laser beam from the fiber laser generator, which may be beneficial in some certain applications. However, a larger lens also means more weight and size, which may be a limiting factor in certain systems or applications.
4. Spot size
The spot size is mainly affected by focal length and lens diameter, and it plays an important role in determining the operating quality. A smaller spot size realizes more precise cuts, while a larger spot is suited for thicker materials or applications requiring deeper penetration.
Smaller spot size: Ideal for high-precision, fine cutting of thinner materials or engraving applications.
Larger spot size: Suitable for dealing with thicker materials or welding, where deep penetration is required.
5. Laser wavelength
In general, fiber lasers typically operate within 1.06 µm wavelength range, which sharply differs from CO2 lasers (10.6 µm). Therefore, it is critical to ensure that lens material is compatible with your laser wavelength.
6. Anti-reflective coating
Many lenses are covered with anti-reflective (AR) coating to raise laser transmission and minimize reflection loss. The coating can keep lens performance over time and ensure consistent focusing, and play a crucial part while using high-power lasers, as they avoid damage to the lens surface and maintain its optical properties.
When choosing lens, please consider whether the lens has AR coating that matches with your laser wavelength to maximize its performance and service life.
IV. Final Conclusion
By considering these factors and specific needs of your fiber laser systems, you can select the proper focusing lens that helps to maximize the potential of your machines. Whether you’re cutting, welding or dealing with different materials, the right focusing lens will keep your fiber laser perform at its best and deliver quality and precise results every time.
