Beam shaping for ultrafast materials processing

Abstract

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.

Dynamic coherent beam combining based on a setup of microlens arrays

“…This offers a new possibility for scientific and industrial applications such as material processing. [6][7][8][9][10] A CBC system is an interferometer with amplifiers in the interferometer arms. The pulses of the common seed source are subsequently split and sent into the interferometer arms, amplified and combined into a single output beam.…”

Ultrafast thin-disk multi-pass amplifier system providing 1.9 kW of average output power and pulse energies in the 10 mJ range at 1 ps of pulse duration for glass-cleaving applications

“…Typically, Bessel-like beams are used for cleaving applications since they offer a unique set of features ideal for separation processes, e.g., high aspect ratio ranging from the millimeter regime in longitudinal direction to few micrometers in transversal direction and high tolerance to surface impurities due to their self-healing nature [35]. In a first experiment, the TRUMPF TOP Cleave optics [35], is deployed to modify a glass sample (SCHOTT Borofloat) of a thickness of 3.8 mm in a single pass exploiting the flexible parameters of the system. We used bursts consisting of 4 individual pulses at a 20 ns temporal distance, each having 250 µJ of pulse energy, at 300 kHz of repetition rate and 300 W of average output power.…”

Structured light for ultrafast laser micro- and nanoprocessing

“…More sophisticated spatial distributions become especially attractive when considering efficient, industry-compatible concepts intended to yield high throughputs. [5][6][7][8] Thus, in addition to the remarkable temporal properties of ultrashort pulsed lasers, there is a need for tailored focus distributions in all spatial degrees of freedom. 6,9,10 Recently, the term "structured light" has been used to cover advanced beam shaping concepts in which all spatial and temporal properties of laser radiation are manipulated to achieve tailored light states.…”

“…[5][6][7][8] Thus, in addition to the remarkable temporal properties of ultrashort pulsed lasers, there is a need for tailored focus distributions in all spatial degrees of freedom. 6,9,10 Recently, the term "structured light" has been used to cover advanced beam shaping concepts in which all spatial and temporal properties of laser radiation are manipulated to achieve tailored light states. 11,12 In the present case, temporal characteristics are determined by the industrial ultrafast laser platforms used with band limited pulses of ∼1 ps duration (or pulse trains thereof, see, e.g., Refs.…”

“…The spatial properties, on the other hand, are determined by efficient and power-resistant concepts based on, e.g., diffractive-optical elements (DOEs), 16,17 free-form optical elements (ROEs), 16,18 or geometric phase holograms 19 (stationary or adaptive versions) illuminated single or multiple times. Together with the focusing unit (used NAs up to 0.5), 6 the beam shaping elements form the processing optics 6 usually fed with free-space or fiber-guided pulses, 20,21 see Fig. 1.…”