A laser scanning galvanometer, often referred to as a galvo scanner or simply galvo, is a device used to rapidly and precisely direct the position of a laser beam in laser systems. It is commonly used in applications such as laser marking, engraving, cutting, welding, and in medical imaging techniques like OCT (Optical Coherence Tomography). Here’s how it works and its key components:
Galvanometer Motors: These are the core of the scanning system. A galvanometer motor is a type of mirror galvanometer used historically in scientific instruments for measuring electric current. In a laser scanning system, these motors control the position of mirrors to deflect the laser beam. Each galvo motor typically controls one axis of movement (X or Y), allowing the laser to be precisely steered across two dimensions.
Mirrors: Attached to the shaft of each galvo motor is a small, lightweight mirror. The mirrors reflect the laser beam, and their angles are adjusted by the galvo motors. Because these mirrors are small and light, they can be moved very quickly, allowing for fast scanning speeds.
Control Electronics: The galvo motors are controlled by sophisticated electronics that convert the input signal into precise angular movements of the mirrors. These electronics typically receive input in the form of digital signals that describe the desired position of the laser beam, and they use this information to adjust the mirrors accordingly.
Position Sensors: These sensors provide feedback to the control system about the actual position of the galvo mirrors. This feedback allows the system to correct any deviations from the intended beam path, ensuring high precision and accuracy in the positioning of the laser beam.
Input/Output Interface: This part of the system communicates with the rest of the laser system or with a computer controlling the laser. It receives the patterns, images, or instructions to be executed and sends signals to the control electronics of the galvo system.
Objective Lens (F-Theta Lens): In many systems, especially those involving flat work surfaces, an F-Theta lens is used in conjunction with the galvo mirrors to keep the laser beam focused and perpendicular to the material surface across the entire scanning area.
Laser scanning galvanometers are valued for their speed and precision. They can reposition the laser beam at high speeds, often thousands of times per second, allowing for fast, precise machining, marking, or imaging with minimal delay between movements. This makes them ideal for applications requiring high-speed laser processing over a two-dimensional area.