Christoph Gerhard

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We report on the development of an efficient and simple picosecond diode-pumped solid-state laser source with a versatile repetition rate (typically 1 Hz-1 MHz) for material processing applications. The laser source is based on a 4 MHz repetition rate mode-locked oscillator and a passive 3D multipass amplifier both based on Nd:YVO(4) crystals.(More)
We report on atmospheric pressure argon plasma-based surface treatment and hybrid laser-plasma ablation of barite crown glass N-BaK4 and heavy flint glass SF5. By pure plasma treatment, a significant surface smoothing, as well as an increase in both the surface energy and the strength of the investigated glass surfaces, was achieved. It was shown that for(More)
In this paper, we present the mode-locked operation of an ultra-robustly stabilised Nd:GdVO(4) laser with low repetition rate by combining quadratic polarisation switching and a semiconductor saturable absorber mirror (SESAM). In addition, similar experiment was also done with Nd:YVO(4). For Nd:GdVO(4), 16-ps pulses at 1063 nm with a repetition rate of 3.95(More)
In this Letter, we report on the near-surface modification of fused silica by applying a hydrogenous atmospheric pressure plasma jet at ambient temperature. A significant decrease in UV-transmission due to this plasma treatment was observed. By the use of secondary ion mass spectroscopy, the composition of the plasma-modified glass surface was investigated.(More)
In this work, we investigated the generation of particles during pure laser and plasma-assisted laser ablation of titanium. Experiments were performed using a NIR picosecond laser at a wavelength of 1030 nm and a pulse duration of 8 ps. For plasma-assisted ablation, an atmospheric pressure dielectric barrier discharge plasma was applied where the process(More)
In this Letter we present a novel approach for increasing the nanosecond laser-induced damage threshold (LIDT) of sapphire windows. It is shown that after direct dielectric barrier discharge plasma treatment at atmospheric pressure for 90 s the LIDT is increased by a factor of 1.5 with respect to untreated samples. Several possible underlying mechanisms are(More)
We report on investigations of the spatial variations of contamination, roughness, and index of refraction of classically manufactured polished fused silica surfaces. Therefore, laser-induced breakdown spectroscopy was used to probe surface and subsurface impurities via the detection of aluminum. Measurements at different positions on the surface of the(More)
In this paper, we present sequential atmospheric pressure plasma-assisted laser ablation of photovoltaic cover glass. First, glass samples were plasma pre-treated using a hydrogenous plasma process gas in order to accomplish a modification of the near-surface glass network by a chemical reduction and the implantation of hydrogen. As a result, the(More)
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