System Composition: The focusing system is used to determine the optimal focal plane for laser processing. The system consists of three main components:
Motion motor: Responsible for moving the optical-path assembly up and down.
Positioning red-light module: Emits two red visible beams to help judge the focal position.
Control board: Receives user commands and controls the motion motor’s actions.
The basic principle of focusing is to change the height of the entire optical-path assembly, thereby changing the distance from the laser source to the workpiece. When this distance makes the laser energy most concentrated and the spot smallest, the focal point is reached.
User places workpiece: Place the workpiece to be processed on the worktable.
Start focusing: Activate the focusing function through the device operation interface.
Drive motor adjustment: The control board sends commands to the motion motor, which moves the optical-path assembly up or down.
Observe the red beams: The device emits two red positioning beams, forming two spots on the workpiece surface.
Judge overlap: When the two red spots completely overlap into one spot, it indicates that the optical-path assembly height is correct and the laser focus is exactly on the workpiece surface.
Complete focusing: The system records the current height, and the user can start processing.
Focused processing means the laser focus is exactly on the workpiece surface. Defocused processing means the laser focus is above or below the workpiece surface. The two have significant differences in actual processing results.
| Item | Focused | Defocused |
|---|---|---|
| Surface topography | Laser energy is concentrated, creating a noticeable depression on the material surface; depth can be felt by touch. | Laser energy is dispersed; the material surface remains largely flat with no obvious pits. |
| Color | Metals appear bright silver-white; non-metals appear their natural color. | Can produce black, gray, or other colors, depending on the material and defocus amount. |
| Material condition | Material is removed by vaporization or ablation. | Material is largely preserved; only surface chemical or physical changes (e.g., oxidation) occur. |
| Wear resistance | Marks are engraved and highly resistant to scratching and wear. | Marks are only surface discoloration and can be easily scratched off. |
| Process residues | Produces smoke, fumes, and fine particles; requires exhaust. | Almost no processing debris; relatively clean. |
| Heat-affected zone | Heat is concentrated in a very small area; instantaneous high temperature may cause slight deformation of thin materials. | Heated area is larger, but overall heat input is controllable; lower risk of deformation. |
Selection advice:
Use focused processing when permanent, wear-resistant marks are needed (e.g., QR codes on metal parts).
Use defocused processing when different colors are desired on the material surface or when surface damage is not desired.
| Item | Diode Laser Module | Fiber Laser Module |
|---|---|---|
| Components | Laser unit (core component generating laser), control PCB (manages laser on/off and power), cooling system (removes heat, prevents overheating) | Laser unit (core component generating laser), isolator (prevents reflected light from damaging the laser) |
| Laser type | Semiconductor laser | Solid-state laser |
| Wavelength | 455 ± 10 nm (visible blue-violet range) | 1064 ± 4 nm (invisible infrared light) |
| Laser class | Class IV (direct or reflected laser can cause eye and skin injury; protection required) | Class IV |
| Measured power | 20 W | 30 W |
| Minimum line width | 0.10 mm (the finest line width achievable with this laser is 0.10 mm) | 0.06 mm (finer than the diode laser, allowing more precise details) |
| Example applicable materials | Wood, leather, plastic, fabric, paper, acrylic, some coated metals – non-metal or light-colored materials | Most metals such as stainless steel, aluminum, copper, brass, titanium, gold, silver, as well as some dark plastics |
1. System Composition
The galvo system is the core component that controls the fast movement of the laser beam. It consists of the following parts:
Galvo motors: Two motors, one controlling the X direction and one controlling the Y direction.
Reflective mirrors: One mirror mounted on each motor, used to reflect the laser beam.
Control card: Receives graphic data from the computer and converts it into motor drive signals.
Bracket: Fixes the motors and mirrors to ensure positional stability.
2. Working Principle
The galvo system uses electric current to drive the mirrors to rotate at high speed. The laser beam first hits the X mirror, reflects to the Y mirror, and then exits from the Y mirror to the workpiece surface. By controlling the angles of the two mirrors, the laser beam can be directed to any position within the processing plane.
3. Detailed Signal Flow
User inputs graphic: The user draws or imports the graphic to be processed (e.g., text, logo, QR code) in the marking software.
Software converts data: The software decomposes the graphic into a series of very dense coordinate points. Each point corresponds to a position the laser beam needs to reach. These points connected form the graphic.
Control card generates signals: The control card reads these coordinate points and converts them into voltage or current signals. The magnitude of these signals determines the angle the mirrors should rotate.
Send to driver: The control card sends the signals to the motor driver. The driver amplifies the signals to provide sufficient current to drive the motors.
Motors execute deflection: The two galvo motors rotate to the specified angles simultaneously according to the received signals.
Laser beam reflection: The laser emits a beam, which reflects off the X mirror and then the Y mirror, exits the output port, and lands on the corresponding coordinate position on the workpiece.
Point-by-point processing: The control card continuously updates the coordinate signals at very high speed. The laser beam moves rapidly across the workpiece surface to complete the entire graphic. During movement, the laser on/off is also synchronously controlled by the control card: laser on when moving to a position that needs processing, laser off when moving between points.
The processing accuracy of the galvo system is affected by many factors. These factors are detailed below in two categories: internal factors and external factors.
Internal factors refer to errors caused by the galvo system’s own components.
1. Motor-related factors
Bearing friction variation: There are bearings inside the motor that support rotor rotation. If bearing friction is unstable (e.g., due to poor lubrication or wear), the force required for motor rotation will fluctuate, causing the final stop position of the mirror to deviate from the commanded position.
Inertia effect: The rotor and mirror have a certain mass. When the motor needs to start or stop quickly, this mass creates inertia. During high-speed jumps (moving from one processing point to another non-continuous point), the mirror may overshoot the target angle due to inertia, or oscillate around the target position, taking time to stabilize. During this time, precise processing is not possible.
Position encoder accuracy: The motor has a built-in encoder that detects the actual angle of the mirror in real time. The higher the encoder resolution, the more accurate the angle detection. Low-precision encoders directly cause positioning errors.
2. Mirror-related factors
Mirror surface flatness: The reflective surface of the mirror must be very flat. If the surface has irregularities or deformation, the reflected laser angle will deviate from the theoretical value, causing spot offset.
Mirror mounting and alignment accuracy: The mirror must be firmly and accurately mounted on the motor shaft. If the mounting position has even a slight offset or tilt, the laser beam path will be incorrect. Also, the relative angle between the two mirrors must be calibrated.
3. Control card factors
Control response speed: There is a time delay between the control card sending a signal and the motor completing the deflection. The faster the control card’s response speed, the more promptly the motor follows commands. Slow response will cause trajectory lag during high-speed processing.
Algorithm compensation capability: A good control card contains compensation algorithms that can pre-correct known errors (e.g., the non-linear relationship between mirror rotation angle and laser spot position). The stronger the compensation capability, the closer the processing result is to the original graphic.
External factors refer to influences from the device’s working environment and input conditions.
1. Environmental factors
Vibration: If the floor or worktable where the device is placed is unstable, external vibrations will be transmitted to the galvo system, causing mirror jitter. Jitter will make the laser spot constantly shift, resulting in thicker lines or uneven edges.
Temperature changes: The galvo motors themselves generate heat during operation. If the ambient temperature is too high and motor heat dissipation is poor, the temperature will continue to rise. Excessively high temperatures can degrade the magnetic material properties inside the motor or change the fit clearance of mechanical parts, causing abnormal motor behavior and inaccurate deflection angles. Temperature fluctuations also cause thermal expansion and contraction of the mirror bracket, changing the optical path length.
Incident beam quality: The quality of the laser beam emitted by the laser directly affects final processing accuracy. If the beam spot shape is irregular or the energy distribution is uneven (e.g., large difference between center and edge energy), even if the galvo system deflects accurately, the spot hitting the workpiece will not be a perfect circle, and the edges will be blurred, resulting in inconsistent line widths or rough edges.
2. Other external factors
Worktable levelness: If the worktable surface is not level, the workpiece surface is not parallel to the laser output plane. Then the focus state of the same graphic at different positions will differ, leading to uneven processing results.
Material surface reflection: Some highly reflective materials (e.g., copper, aluminum) reflect part of the laser energy back. Reflected light entering the galvo system or laser may interfere with normal operation or even damage components.