Introduction to laser technology
What is a laser head?
The laser head in a fiber laser is a key optical component that focuses the fiber laser beam onto the surface of the material being processed. It contains lenses and other optical elements that precisely shape and direct the beam, determining its size, shape, and power at the point of impact. This laser module is responsible for the accuracy and quality of engraving or cutting.
The head module is usually an independent component mounted on a stand. This allows the focal height to be adjusted manually using a knob or automatically, and also displays a preview of the marked design. The service life of laser heads is typically around 100,000 operating hours.
How does a 20W laser work in points?
Below are the most important elements of a 20W laser:
Light source
A laser diode generates light that is fed into an erbium-doped fiber
Amplification
As the light travels through the fiber, it is repeatedly amplified by the phenomenon of stimulated emission in the ytterbium atoms, which are excited by the light from the pump diode.
Beam generation
In an optical resonator (often constructed of mirrors or diffraction gratings), the amplified light oscillates, forming a coherent laser beam of a specific wavelength (usually around 1064 nm).
Beam delivery
The laser beam is guided through a transmission fiber to the laser head.
Beam focusing
The laser head contains lenses and other optical elements that focus the beam to a very small diameter on the surface of the material being processed.
Material processing
The concentrated energy of the 20W laser causes local heating, melting, vaporization, or chemical change of the material, enabling marking, engraving, or thin cutting.
A power of 20W means that the maximum laser beam power delivered to the workpiece is 20 watts. This is sufficient for many applications in marking and engraving metals and plastics, as well as for thin cutting of certain materials.
The use of laser technology in industry
Laser technology has found widespread use in many industries, revolutionizing manufacturing processes and offering unique capabilities. In short, lasers are used in industry for:
- Cutting: Precise cutting of complex shapes in metals, plastics, wood, textiles, and other materials with high accuracy and repeatability.
- Welding: Joining metals and plastics at high speeds with minimal heat-affected zones and high weld quality.
- Marking and engraving: Permanent marking of products with serial numbers, barcodes, production dates, logos, and graphics on a variety of materials.
- Surface treatment: Hardening metal surfaces, cleaning surfaces of rust and contaminants, texturing and modifying material properties.
- Drilling: Wykonywanie precyzyjnych otworów, nawet o bardzo małych średnicach, w różnych materiałach.
- Welding: Applying layers of material to regenerate worn parts or improve their properties.
- Metrology and quality control: Precise measurements of distance, shape, and surface defects.
- Additive manufacturing (3D printing): Sintering metal or plastic powders to create three-dimensional objects with complex shapes, which have found application in 3D printers using SLS technology.
Thanks to its precision, speed, versatility, and automation capabilities, laser technology has become an indispensable tool in many industries, contributing to increased productivity, reduced costs, and improved product quality.
Specification of the 20W laser head
Technical parameters of the laser module
Here are some example technical parameters for a 20W fiber laser module. Keep in mind that specific values may vary depending on the manufacturer and model:
Basic Laser Output Parameters:
- Laser output power: 20 W (average continuous power)
- Laser wavelength:Typically 1064 nm (near infrared)
- Operating mode: Continuous (CW) or pulsed - Many 20W fiber lasers offer pulsed operation, which is crucial for marking and engraving.
- Pulse frequency (if pulsed): The range can be wide, e.g., from 20 kHz to 80 kHz (or more), with adjustable settings.
- Pulse width (if pulsed): Typically in the range of a few nanoseconds to several hundred nanoseconds, adjustable.
- Pulse energy (if pulsed): The maximum pulse energy will depend on the average power and frequency, e.g., up to 1 mJ.
- Beam quality (M²): Typically low, close to ideal Gaussian (M² < 1.5 or even < 1.1), which ensures good focusability and precision.
- Output power stability: Typically very good, e.g., < ±1% over several hours.
The importance of optical power in engraving
The optical power of the laser in engraving directly determines the amount of energy delivered to the material per unit of time. Higher power means:
Faster material removal
Allows deeper and faster engraving at the same head speed.
Ability to work with more difficult materials
Enables engraving of materials with higher density or higher melting/vaporization temperatures.
Greater flexibility in parameter selection
Allows you to achieve different effects (e.g., deeper, darker engraving) with different speed settings and number of passes.
Too low power may result in poor or invisible engraving, the need for multiple passes, or the inability to process the material. Too high power can lead to burning, excessive melting or damage to the material. Therefore, selecting the right optical power is crucial for achieving optimal engraving results in terms of quality, speed and process safety.
Laser engraving and cutting
Laser engraving process
The laser engraving process involves focusing an intense beam of laser light onto the surface of the material, causing it to heat up, melt, vaporize, or change color/structure locally. The controlled movement of the beam, according to a pre-designed pattern, creates a permanent mark—an engraving—on the surface of the material.
Factors affecting the quality of engraving
The laser power will certainly affect the quality of cutting, engraving, and marking. With a power of 20 W, which can be adjusted from 0 to 20 W, we can achieve fast and precise engraving quality. When cutting metals, the time at 20 W laser power can cause the metal to heat up, and by repeatedly passing over the same edge of the cut surface, some imperfections or sharpening may appear. In such a case, if we apply high power, e.g. 50 W or more, we will achieve a better effect.
Laser modules and accessories
Lens selection
When selecting a lens for a fiber laser, the following key criteria must be taken into account:
- Laser wavelength: The lens must be optimized for the specific wavelength of the fiber laser (usually 1064 nm). An incorrect wavelength results in poor focus and power loss.
- Focal length (f): Determines the working distance (from the lens to the material) and the size of the laser spot. A shorter focal length results in a smaller spot (higher precision but lower depth of field and smaller working area), while a longer focal length results in a larger spot (lower precision but higher depth of field and larger working area). The choice depends on the application (e.g., precision engraving vs. engraving larger areas).
- Field of view (working area): Specifies the maximum area that can be engraved or marked without moving the material or the head. It is related to the focal length and optical design.
- Transmittance: The lens should have high transmittance for the given wavelength to minimize laser power loss.
- Laser power resistance: The lens material and coatings must be resistant to high fiber laser power to avoid thermal damage.
- Aberrations: The lens should minimize optical aberrations (e.g., spherical, chromatic) that can degrade beam focusing quality.
- Lens material: Fused silica is most commonly used due to its high transmittance and resistance to laser damage.
- Anti-reflective coatings (AR): Multi-layer coatings reduce light reflection from the lens surface, increasing transmittance and protecting against damage.
- Lens diameter and mounting thread: These must be compatible with the holder and mounting system in the laser head.
The precise selection of the lens is crucial for achieving optimal quality, speed, and efficiency in the fiber laser engraving process.
Accessories and their adaptation to fiber lasers
There are many accessories available to enhance and improve the ease of use of advanced laser technology. Accessories can be safety elements, such as special cages that protect the operator’s eyes from direct exposure to the reflected laser beam. These can be various types of vices for holding objects, which improves quality and guarantees quick material change. For serial production and customization, belt feeders with customized slots for different objects are the ideal solution, feeding the object to the head at the right moment for marking.
Laser control software
Introduction to LightBurn
LightBurn is powerful yet intuitive software for controlling CO2, diode, and fiber lasers. It is used for designing, importing graphics, setting cutting and engraving parameters, and communicating directly with the laser machine. Its user-friendly interface and extensive capabilities make it a popular choice for both hobbyists and professionals. It allows for precise control over the laser processing, offering advanced configuration and optimization options.
Remote control options in laser engraving
Remote control options for laser engraving allow you to monitor and control the processing without being physically present at the machine. They most commonly include:
- Network connection (Ethernet/Wi-Fi): Allows you to control the laser and transfer projects from a computer located in another part of the workshop or building.
- Touchscreen with network interface: Some systems have built-in touchscreens that can be operated remotely via a web browser or dedicated app.
- Software with remote access features: Some control programs (e.g., LightBurn with a camera and appropriate configuration) allow real-time viewing and basic control from another device on the network.
- Mobile apps: Some manufacturers offer smartphone or tablet apps for monitoring machine status, viewing work progress, and sometimes even pausing or resuming the process.
These options increase convenience, enable monitoring of long-term processes without the need for constant supervision, and allow integration with other production management systems.