Z-Scanning For Laser Processing Focus Control

In laser-based manufacturing, a team of researchers has discovered a rapid way to track a surface’s precise location and adjust the focus of an optical system. They employed axial varifocal optics, specifically a TAG lens, which operates at 0.1-1 MHz, avoiding mechanical motion delays in the beam propagation direction. The researchers used dynamic z-scanning for detection and movement simultaneously, with no mechanical axial movement. The interval between surface detection, focus recovery, and firing of the manufacturing laser pulse is theoretically less than two z-scanning periods, or a few microseconds, which is substantially faster than any mechanically based re-focusing system paired with secondary surface position sensor elements.

The researchers combined A single varifocal lens into a dual laser beam configuration consisting of probing and manufacturing beams. The probing beam moves continuously along the z-axis, and its reflection’s temporal response corresponds to the surface’s location. The manufacturing beam is simultaneously steered to the correct spot by initiating the fabrication laser at the proper time.

This method lowers defocused laser pulses while increasing processing speed when processing non-flat or moving data. The researchers also emphasized the technique’s potential for auto-focusing with a lab-built real-time detecting and focusing mechanism. This revolutionary axial focus alignment technique opens up new opportunities for high-speed material processing of non-flat and varied surfaces.

Researchers anticipate that the change from the mechanical motion of optical parts to dynamic light beam shaping will continue to inspire new applications in optical metrology and 3D laser manufacturing.

The technology developed by the team provides a quick and effective option for auto-focusing in laser processing. The researchers dramatically shortened processing times and improved the quality of laser marking on non-flat surfaces by eliminating mechanical motion delays. As laser-based manufacturing evolves, breakthroughs such as dynamic z-scanning will be critical in unlocking new opportunities for enhanced efficiency and productivity across multiple industries.

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