In the world of precision laser material processing, speed and accuracy drive innovation and productivity. The ability to direct a powerful laser beam with microscopic precision at incredibly high speeds is what enables everything from the rapid drilling of millions of microvias in a PCB to the intricate cutting of life-saving medical stents. The technology at the heart of this high-speed, high-accuracy beam steering is the galvanometer laser scan head, often called a galvo laser head.
Galvo scan heads are a crucial component in advanced manufacturing systems. Understanding what they are, how they work and what they can do is fundamental to optimizing any laser processing application. This guide serves as a technical deep-dive into this essential technology, explaining these core principles and showcasing the applications that rely on galvo laser scan heads’ unique capabilities.
A laser scan head is an opto-mechatronic device designed to steer a laser beam across a workpiece with high speed and precision. It acts as the final beam delivery component, taking the collimated laser beam and directing it to specific points or along complex paths within a defined area known as the field of view (FOV).
A scan head consists of one or more small, lightweight mirrors mounted onto highly dynamic motors. By precisely controlling the angular rotation of these mirrors, the scan head can redirect the laser beam in two or three dimensions. The steered beam then passes through a focusing lens (typically an F-theta lens) that focuses the laser spot onto the workpiece and translates the angular motion of the mirrors into linear motion across the focal plane.
The primary function of a laser scan head is beam steering. Its purpose is to move the laser spot across the workpiece far more rapidly than is possible with traditional mechanical stages like X/Y tables. While large gantry systems are excellent for moving a workpiece or the entire processing head over large distances, a scan head excels at creating intricate, small-scale features within its field of view at very high velocities.
Key functions include:
Rapid Positioning: Quickly jumping the laser spot from one point to another for applications like high-density drilling or marking.
Vector Processing: Tracing complex vector paths for cutting, scribing or engraving applications.
Raster Scanning: Sweeping the beam back and forth to fill an area, common in surface texturing or ablation.
In advanced systems like those from Aerotech, the scan head is treated as just another precision motion axis, seamlessly integrated and synchronized with other linear and rotary stages to enable complex, multi-axis manufacturing processes.
A laser scan head is used for a multitude of applications where the rapid and precise placement of laser energy is paramount. The high speeds achievable with galvanometer-based scanners make them essential for maximizing throughput in industrial settings.
Common applications include:
Laser Marking and Engraving: Quickly creating serial numbers, logos and other identifiers on products. This is one of the most common uses for galvo scanners.
Laser Drilling: Performing high-speed percussion or trepanning drilling for microvias in electronics, cooling holes in turbine blades and perforations in packaging materials.
Laser Cutting and Scribing: Cutting intricate patterns in thin materials like flexible circuits or scribing lines on brittle materials like glass and silicon wafers for controlled breaking.
Laser Welding: Performing "wobble" welding to create wider, more consistent seams or rapidly stitching together multiple weld spots.
Additive Manufacturing (3D Printing): In processes like selective laser sintering (SLS), galvo scanners are used to rapidly trace the cross-section of a part in a bed of powder, selectively fusing it layer by layer.
Surface Texturing and Ablation: Creating precise surface patterns to modify friction or wettability, or selectively removing material for micromachining.
The core laser scanner working principle for a galvo system is based on the use of galvanometers—high-speed, closed-loop rotary motors—to drive mirrors. A typical 2-axis galvo scanner has two of these motors and mirrors arranged orthogonally. One mirror deflects the laser beam in the X direction, and the second deflects it in the Y direction. By sending a precise control signal to each galvanometer, the mirrors can be rotated to precise angles, thereby steering the laser beam to any coordinate within the scanner's field of view.
The system operates in a closed-loop fashion. High-resolution encoders continuously measure the exact angular position of the mirrors. This feedback is sent back to the controller, which compares the actual position to the commanded position and adjusts the motor current in real-time to minimize any error. This closed-loop control is what enables both the high speed and the high accuracy of the system. Sophisticated servo control algorithms are essential for minimizing tracking errors and ensuring the laser spot is placed exactly where intended, even during rapid acceleration and deceleration. This answers the fundamental question of what is a galvo laser—it's a laser system where the beam is directed by this high-speed, precision-controlled galvanometer mechanism.
A galvo scanner takes a static, incoming laser beam and turns it into a dynamic, two-dimensional tool. It translates electronic command signals into precise, high-speed mechanical motion of mirrors, which in turn steers the laser beam. Essentially, a galvo scanner "draws" with light.
By controlling the angle of its mirrors, a galvo scanner can make the laser spot:
Jump: Move from point A to point B nearly instantaneously for "step-and-settle" applications like drilling a grid of holes.
Trace: Follow a complex vector path like a circle, spiral or intricate filigree pattern for cutting or engraving.
Scan: Move back and forth in a raster pattern to cover a specific area for surface processing.
In more advanced 3-axis or 5-axis systems, the scanner does even more. A 3-axis galvo scanner incorporates a dynamic focusing module to move the focal point along the Z-axis, allowing it to process on 3D surfaces or at different depths. A 5-axis scanner, like Aerotech's AGV5D, adds beam tilting and rotation, giving complete control over the angle of incidence for creating features with complex cross-sections, like tapered or cylindrical holes with perfectly vertical sidewalls.
A galvo laser system can perform a vast array of high-precision manufacturing tasks that would be slow, inefficient, or impossible with other methods. Its ability to move a focused energy spot at speeds of several meters per second opens up numerous industrial capabilities.
A galvo laser can:
Cut intricate patterns in flexible circuits, stents and thin films with micron-level accuracy.
Drill millions of microvias per hour in printed circuit boards, enabling the high-density interconnects required for modern electronics.
Weld delicate medical components with hermetic seals and minimal heat input.
Mark permanent, high-contrast codes and logos on nearly any material for traceability and branding.
Selectively ablate material from a surface with extreme precision to create microfluidic channels or texture a surface.
Build complex 3D parts layer-by-layer in additive manufacturing processes.
Process large areas seamlessly by combining the scanner's high speed with the long travel of servo stages, a technique known as Infinite Field of View (IFOV).
The choice of the best galvo laser system depends on the application's specific requirements for speed, accuracy, spot size and field of view. By carefully selecting from the best galvo laser scan heads and integrating them into a complete motion system, manufacturers can unlock significant gains in throughput and part quality.
The laser drilling process is a thermal material removal technique that uses a focused laser beam to create holes. When the high-intensity laser pulse strikes the material, it is absorbed and rapidly heats the material to its vaporization point. The recoil pressure from the vaporizing material, along with an assist gas jet, expels the molten and vaporized ejecta from the hole.
Galvo laser scan heads are critical for several advanced laser drilling techniques:
Percussion Drilling: The galvo scanner rapidly positions the beam to each hole location, where one or more laser pulses are fired to create the hole. The scanner's high "jump" speed minimizes the time between drilling holes, maximizing throughput.
Trepanning: To create a hole larger than the laser spot size or with a better-quality edge, the galvo scanner steers the beam in a small circle. This effectively "cuts out" the hole's circumference.
Helical Trepanning: For deep or precisely-shaped holes, the galvo scanner moves the beam in a spiral or helical path, machining the hole layer by layer. This allows for precise control over the hole's taper and sidewall quality.
These processes are fundamental to modern electronics and aerospace manufacturing, where the ability to quickly and cleanly drill thousands or millions of precise holes is a key production step.