arXiv subjects

Julian Hellstern

Publications and source records attributed to Julian Hellstern.

5 recordsLinked to original sources

arXiv2024

Optical tools for laser machining along six orders of magnitude

We present an overview on the development and characterization of multiscale laser processing optics for versatile material modifications across more than six orders of magnitude. Starting with solutions for micromachining we present high-NA microscope objectives creating sub-wavelength material modifications on macroscopic scales with highest peak intensities. Moving on to the millimeter range, the adaptability and scalability of scanning optics is examined for large-area machining. Finally, we explore line beam optics in the meter range, evaluating their use in uniform material processing using average powers above 100kW. This study provides an insight into the design and performance characteristics of such optics and demonstrates their potential in advanced laser processing.

physics.optics↗

arXiv2021

Structured light for ultrafast laser micro- and nanoprocessing

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 novel 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 non-diffracting beams and 3D-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.

physics.optics↗

arXiv2021

Anamorphic beam shaping for efficient laser homogenization: methods and high power applications

The homogenization of light is widely applied in various industrial sectors. The uniform high power processing of large areas requires a high degree of homogeneity. Sophisticated beam transformation techniques are used to optimize the illumination of standard optical diffusers such as microlens arrays and decrease the contrast of interference. Novel design techniques take advantage of a multimodal approach which is especially adapted to the characteristic properties of the laser light source. We show how anamorphic beam shaping is employed to transform the high power light source in order to meet the required level of homogeneity suited for the respective application.

physics.optics↗

arXiv2020

Beam shaping for ultrafast materials processing

The remarkable temporal properties of ultra-short pulsed lasers in combination with novel beam shaping concepts enable the development of completely new material processing strategies. We demonstrate the benefit of employing focus distributions being tailored in all three spatial dimensions. As example advanced Bessel-like beam profiles, 3D-beam splitting concepts and flat-top focus distributions are used to achieve high-quality and efficient results for cutting, welding and drilling applications. Spatial and temporal in situ diagnostics is employed to analyze light-matter interaction and, in combination with flexible digital-holographic beam shaping techniques, to find the optimal beam shape for the respective laser application.

physics.optics↗

arXiv2020

High-quality Tailored-edge Cleaving Using Aberration-corrected Bessel-like Beams

We report on the usage of ultrashort laser pulses in form of aberration-corrected Bessel-like beams for laser cutting of glass with bevels. Our approach foresees to incline the material's entrance surface with respect to the processing optics. The detailed analysis of phase distortions caused by the beam transition through the tilted glass surface allows to pre-compensate occurring aberrations using digital holography. We verify theoretical considerations by means of pump-probe microscopy and present high-quality edges in non-strengthened silicate glass.

physics.optics↗