All About Scan Angle and Crosshatch
Scan angle controls the direction of the parallel paths the laser's movement system follows while filling a shape. Crosshatching adds one or more additional scan directions, while angle per pass can rotate the fill direction between repeated passes.
Physical effect
Changing the scan direction changes how neighboring laser paths meet edges, surface grain, brushed finishes, and grooves created by previous passes. It can also change how the laser's movement system uses its fast and slow axes. Scan angle does not change line interval by itself, but it rotates the direction in which that spacing is applied across the workpiece.
Crosshatch
Crosshatching engraves the same region using two or more sets of scan lines at different angles. It can reduce directional texture and improve coverage, but it also increases processing time and total laser exposure. Power, scanning speed, or pass count may need to be adjusted to prevent excessive heat accumulation.
Examples
Align the scan direction with the grain of brushed metal to emphasize the existing finish, or cross the grain to make the new mark more visible. Rotate a fill to reduce edge scalloping on a particular feature. Use 0-degree and 90-degree passes to create a balanced grid texture, or change the angle per pass to distribute repeated engraving more evenly. Use one controlled scan angle for diffraction grooves intended to direct reflected light toward a chosen viewing direction.
Geometry and machine effects
Some scan angles require more short line segments or more overscan travel than others. This can change processing time and reveal differences in acceleration, timing, or galvo calibration even when the laser settings remain unchanged.
Testing
Test scan angles on the actual surface finish and inspect the result from the viewing directions that matter for the finished piece. When enabling crosshatching, treat every added scan direction as additional laser exposure, not as a purely visual option.