We present an optical concept and adapted ultrashort pulsed laser parameters for a precise cleaving process of flexible ultrathin glasses. To this end, non-diffracting beams with tailored transverse intensity profiles generate asymmetric type-III-regime modifications along the entire substrate thickness. These laser-induced material changes not only show advantages in cutting but can also improve the bending properties of these flexible glasses when arranged in a specific manner. During the relative movement of the workpiece to the processing optics, crack connection occurs between the specifically aligned modifications only, which considerably facilitates glass separation and increases yield.
KEYWORDS: Nondiffracting beams, Axicons, Glasses, Beam shaping, Near field optics, Laser cutting, Etching, Phase shift keying, Materials processing, Near field
We report on the design and realization of novel non-diffracting beams for ultrashort laser materials processing. Our method is axicon based and introduces subtle azimuthal modifications to the conical lenses or well-defined misalignments to achieve a set of novel non-diffracting beams. These focus distributions retain all well-known advantages of non-diffracting beams, such as self-healing, high optical efficiency, or possible extreme aspect ratios. Additionally, tailored transverse intensity profiles with, for example, well-defined preferential direction can be generated. Clear advantages for controlling residual stress and crack orientation in glass processing are discussed and results of different micro-machining experiments are presented.
The industrial maturity of ultrashort pulsed lasers has triggered the development of a plethora of material processing strategies. Recently, the combination of these remarkable temporal pulse properties with advanced structured light concepts has led to breakthroughs in the development of laser application methods, which will now gradually reach industrial environments. We review the efficient generation of customized focus distributions from the near-infrared down to the deep ultraviolet, e.g., based on nondiffracting beams and three-dimensional-beam splitters, and demonstrate their impact for micro- and nanomachining of a wide range of materials. In the beam shaping concepts presented, special attention was paid to suitability for both high energies and high powers.
Ultrashort pulsed lasers represent unique tools for the processing of micro-optical components. Pulse durations around 1 ps and corresponding extreme peak intensities lead to interaction processes with all conceivable materials. As parts of almost every optoelectronic device, transparent materials represent a particularly challenging example for processing. Here, a controlled energy deposition at the surface or inside the volume is required while maintaining optical properties or implemented functionalities of adjacent areas. The talk will review strategies for the micro-processing of transparent materials that become possible by spatiotemporal beam shaping. Here, the beneficial use of non-diffracting beams is discussed as well as 3D-beam splitting approaches.
We generalize the well-known method of generating nondiffracting beams based on axicons in the near-field using phase modulations with azimuthal dependencies. The enormous benefit of our concept for efficient shaping of nondiffracting beams with arbitrary transverse profiles is shown and optimized processes like cleaving of particularly thin and thick glasses using elliptical Bessel-like beams are discussed.
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