Focal Length

Focal length describes the distance from the cutting lens to the focal plane where the laser beam is focused at its tightest point. This distance is critical because it determines where the maximum beam intensity is concentrated, which directly affects cut quality, cut width, and the degree of heat-affected zone distortion on surrounding material.

Different cutting head designs and nozzle styles have different focal lengths, typically ranging from 5 to 10 inches depending on the optics. Setting the focal length correctly during machine setup is essential, if the focal plane is too high or too low above the material, the concentrated energy is lost and cuts become ragged and slow.

Modern laser systems use height sensors and automated focus-follow systems to maintain proper focal length as the cutting head moves across material warping and surface irregularities, ensuring consistent cut quality across the entire sheet.