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Lenses are a crucial component of any CO2 laser machine, as their quality directly impacts the precision, efficiency, and durability of the equipment. When selecting a lens, it is important to understand the material it is made from and the manufacturing method used, as these factors significantly influence its performance. In this article, we will explore the materials used to produce lenses and provide a detailed comparison between lenses made using the PVD and CVD methods.

Materials Used for CO2 Laser Machine Lenses
Lenses for CO2 laser machines are made from a variety of materials, with the most common being zinc selenide (ZnSe). These lenses are easily recognizable due to their yellow color and high transparency. Their key advantages include high thermal resistance, which ensures a longer lifespan, and excellent light transmission, allowing the laser beam to pass through with minimal distortion and optical loss. This results in superior cutting and engraving quality.

Another material used for laser lenses is gallium arsenide (GaAs). These lenses are silver in appearance and resemble small mirrors. The primary advantage of GaAs lenses lies in their resistance to mechanical stress, making them ideal for demanding environments, such as cutting paronite. Additionally, they endure more cleaning cycles compared to ZnSe lenses. However, GaAs lenses have lower transmission efficiency and are more expensive to produce. Moreover, the powdered form of gallium arsenide is toxic, complicating the manufacturing process. As a result, GaAs lenses are less commonly used.

There are also lenses made from germanium (Ge), but these are less suitable for CO2 laser cutting or engraving due to their high absorption at a 10.6 μm wavelength, which makes them prone to overheating. When overheated, they lose their transparency, making them impractical for most modern applications.

The Best Choice: ZnSe Lenses
Given their high transparency, thermal resistance, and cost-effectiveness, ZnSe lenses are the preferred choice for most applications. These lenses not only deliver outstanding performance but also come in various types based on the manufacturing method.
ZnSe Lens Manufacturing Methods: PVD vs. CVD
When selecting ZnSe lenses, you will often encounter the abbreviations PVD (Physical Vapor Deposition) and CVD(Chemical Vapor Deposition). These terms refer to the methods used to grow the lens crystals, which significantly influence their quality and cost.
PVD Lenses
PVD lenses are more affordable and environmentally friendly to produce. However, they have a significant drawback—they generally cannot handle power levels exceeding 80-90 watts. This limitation makes them less suitable for high-power applications.

CVD Lenses
In contrast, CVD lenses are capable of withstanding power levels of up to 200 watts, offering higher transmission efficiency. More importantly, the CVD method produces lenses with a sharper and more concentrated laser beam spot. The better the focus of the laser beam, the higher the quality of the cutting and engraving results. For this reason, leading lens manufacturers in the United States prioritize the CVD method for their ZnSe lenses.

Why Wattsan Uses CVD Lenses
At Wattsan, all CO2 laser machines are equipped with American-made CVD lenses as part of their standard configuration. These lenses deliver superior cutting performance, longer service life, and, most critically, can withstand the high power levels of Wattsan machines.
Conclusion
In this article, we have explored the materials used to manufacture lenses for CO2 laser machines, highlighting the differences between Chinese PVD lenses and American CVD lenses. The choice of material and production method directly impacts the lens’s performance, making ZnSe CVD lenses the optimal solution for high-quality cutting and engraving tasks.