CO2 lasers are among the earliest, most widely used, and most mature high-power lasers. They boast high efficiency, high power, and excellent absorption by non-metallic materials. Consequently, CO2 lasers hold an irreplaceable position in cutting, engraving, and welding. While all CO2 lasers use CO2 gas as their core medium, manufacturers design them in various forms. These designs adapt to different industrial demands. They vary by gas circulation, cavity structure, and excitation methods.
I. Sealed-Off CO2 Lasers: The Economical “Sealed Can”
A sealed-off CO2 laser, as its name suggests, resembles a “sealed can.” Its key feature is that the laser gas remains permanently sealed inside the tube. It does not undergo external circulation. For instance, the glass tube CO2 laser you inquired about is a typical sealed-off type.
This design is very compact and small. It offers a simple structure and lower cost. Such CO2 laser systems typically use water or air cooling. Their small size makes integration into small and medium-sized equipment easy. However, the gas never refreshes. Over time, CO2 gas gradually decomposes during discharge. This leads to a slow decline in laser power. Consequently, sealed-off CO2 lasers have a relatively shorter average lifespan. They usually serve in medium-to-low power applications like fine marking, engraving, or thin material cutting. For users with strict size and budget constraints, who also have less extreme demands on laser tube longevity, sealed-off CO2 lasers present an economical choice.
II. Axial-Flow CO2 Lasers: The High-Power “Open Water Circulation System”
In contrast to sealed-off types, an axial-flow CO2 laser resembles an “open water circulation system.” Its key feature is the flowing working gas within the tube cavity. The gas circulates at high speed axially (along the optical axis).
In an axial-flow CO2 laser, a pumping system (e.g., a Roots pump or turbopump) circulates the gas. This system continuously cools and purifies the gas. It also periodically replenishes fresh CO2 gas. This high-speed gas flow efficiently removes the large amount of heat generated during discharge. It also ensures stable laser power. Furthermore, it effectively suppresses the negative effects of CO2 decomposition. Consequently, axial-flow CO2 lasers achieve higher output power (medium to high). They also operate stably for extended periods. These CO2 lasers primarily serve in high-power, high-efficiency industrial cutting and welding. They form the core of many heavy-duty metal processing machines.
III. Slab CO2 Lasers: The “Technological Innovator”
A slab CO2 laser represents a “technological innovator” within the CO2 laser family. It moves away from traditional cylindrical discharge tubes. Instead, it uses two parallel, closely spaced electrode plates as the discharge region. This design resembles a flat “slab.”
This design introduces a revolutionary cooling method. The laser gas’s contact surface area with the electrode plates significantly increases. Heat diffuses efficiently through the plates. This high cooling capacity allows for high power density output, even without high-speed gas circulation. Slab CO2 lasers offer compact structure, good beam quality, and low maintenance costs. They are especially suitable for precision processing. These applications demand precise spot shape control and high stability. Slab CO2 lasers are gaining popularity in modern automotive manufacturing and electronic component processing.
IV. Waveguide CO2 Lasers: The “Miniaturization Expert”
A waveguide CO2 laser is the “miniaturization expert” among CO2 lasers. As its name implies, it utilizes the waveguide effect to confine and guide the laser beam. Its cavity is extremely narrow. It typically features square or circular ceramic channels. These channels have inner diameters of just a few millimeters or even less.
This tiny structure gives the CO2 laser extremely high beam quality and a very small footprint. Waveguide CO2 lasers are typically sealed-off. They feature a compact structure, long lifespan, and high stability. They primarily serve applications requiring extreme precision and small size. Examples include fine cutting in medical surgery and beauty equipment. They also excel in highly integrated precision electronic marking. Indeed, the waveguide CO2 laser is the preferred choice for high-precision, compact CO2 laser applications.
Summary
From the “elder statesman” axial-flow type, which requires external circulation, to the “sealed can” sealed-off type, which needs no circulation; from the “flat structure” slab type, which prioritizes efficient heat dissipation, to the “channel expert” waveguide type, which achieves miniaturization—each evolution of the CO2 laser family aims to better meet diverse industrial demands for power, precision, size, and cost. Understanding their individual characteristics empowers you to make the most informed decision when selecting a CO2 laser system.