System Integration: Laser galvo for fast overhead moving beam and high throughout
High Speed Laser Beam Scanning Galvanometers
2-axis and 3-axis, Industrial versus retail plus a few words on Laser Safety
Simply put, a galvanometer, galvo for short, is a mirror on a motorized shaft that twitches to scan a beam, commonly called a scanner. Laser galvos are famous as supermarket and other point-of-sale barcode scanners, many hundreds of thousands are in use throughout the world.
An industrial laser galvo is just a souped up retail scanner with a high power laser and big mirrors in the galvo. Typical industrial applications are marking IDs & bar codes, etching images, resistor trimming and patterning displays comprising thin film coatings on glass or plastic substrates.
Industrial lasers are more powerful than point-of-sale scanners because they do micromachining. High power requires eye safety precautions. Retail barcode scanners are USA Government classified Class I eye safe lasers without need for shielding because the power is about one milliwatt. High power industrial laser machines require shielding to qualify for a Class I rating. Without shielding, they are Class IIIb or IV.
A two mirror galvanometer is a 2-axis XY galvo. Actually, it swings the laser focal point in an arc which then requires flattening in the XY plane using a so-called F-theta lens. The Z-axis is non-adjustable.
Laser writing speeds of meters/sec are possible with a large laser flying spot and a high laser rep rate.
3-axis Laser Galvo
An XYZ or 3-axis galvo substitutes the large F-theta lens with a small lens moving on a linear track along the direction of the beam. This controls the up and down Z-axis focal point. The technical name for this lens is Galilean telescope and there are actually two lenses, one negative, the other positive. The negative lens is motorized to move the laser focal point up and down to flatten it in the X-Y plane.
Video (CCTV) viewing of the worksite are worthy issues to discuss relative to moving beam optics (galvo) versus fixed beam. Other issues are speed, accuracy and resolution.
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