Glass processing

Glass is transparent and brittle: conventional and thermal methods chip it, crack it, and leave tapered walls. Femtosecond laser pulses deposit energy faster than heat can spread, so glass can be drilled into high-aspect-ratio vias, milled and cut with smooth walls, scribed kerf-free by Bessel beams, or modified for selective chemical etching.

Material processing
Material processing Glass Metal Polymer Other materials
Glass

Laser-based Bessel beam scribing

Bessel beam scribing is the most efficient laser-based, kerf-free method for scribing glass. The technique introduces intra-volume voids, and the glass is then separated mechanically or thermally. Sidewalls come out smooth, and because only a single laser pass is required, scribing speeds are high.

A FemtoLux femtosecond laser in MHz burst mode, combined with a Bessel beam, scribes soda-lime glass 1 – 4.8 mm thick with minimal surface chipping. At 4.8 mm the scribing speed reaches 80 mm/s and sidewall roughness stays below 0.5 µm. Sapphire was scribed at 300 mm/s, also with a smooth sidewall.

The polarization state controls how the microcracks are oriented. In 1 mm soda-lime glass, turning the linear polarization parallel to the scribing direction aligns them with the cut and reduces the separation stress from about 60 to 15 MPa. At a 7 µm pitch the stress falls to 7.3 MPa, which corresponds to a scribing speed of 140 mm/s at 3.6 W of average power, with sidewall roughness still below 1 µm.

Laser-based Bessel beam scribing of 4.8 mm soda-lime glass.

Laser-based Bessel beam scribing of 4.8 mm soda-lime glass.

Courtesy of FTMC.

Scribed 4.8 mm soda-lime edge view.

Scribed 4.8 mm soda-lime edge view.

Courtesy of FTMC.

Scribed 1 mm soda-lime sidewall view.

Scribed 1 mm soda-lime sidewall view.

Courtesy of FTMC.

Sapphire sidewall after stealth dicing.

Sapphire sidewall after stealth dicing.

Courtesy of FTMC.

Publications

Femtosecond Applications Glass Processing Material Processing Micromachining Scribing FemtoLux
Polarization-Dependent Laser-Assisted Cutting of Glass Using a Nondiffractive Beam in the MHz Burst Regime
J. Dudutis, A. Kondratas, and P. Gečys, ACS Photonics 12 (7), 3706-3716 (2025). DOI: 10.1021/acsphotonics.5c00679.

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