Mr. Daniel Bartoschewski Profile

Daniel Bartoschewski

at LIMO GmbH

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Publications (3)

Proceedings Article | 24 February 2009 Paper

Intensity increasing up to 4 MW/cm2 with BALB's via wavelengths coupling

Andre Timmermann, Daniel Bartoschewski, Stephan Schlüter, Colin Burke, Jens Meinschien

Proceedings Volume 7198, 71980X (2009) https://doi.org/10.1117/12.807430

KEYWORDS: Semiconductor lasers, Diodes, Laser cutting, Laser marking, Laser applications, Micro optics, Beam shaping, Metals, Polarization, Laser welding

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Proceedings Article | 25 February 2008 Paper

Next generation high-brightness diode lasers offer new industrial applications

Andre Timmermann, Jens Meinschien, Peter Bruns, Colin Burke, Daniel Bartoschewski

Proceedings Volume 6876, 68760U (2008) https://doi.org/10.1117/12.763918

KEYWORDS: Semiconductor lasers, Laser cutting, Diodes, Laser marking, Laser welding, Collimation, Micro optics, Laser applications, Beam shaping, Laser systems engineering

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So far, diode laser systems could not compete against CO₂-lasers or DPSSL in industrial applications like marking or cutting due to their lower brightness. Recent developments in high-brightness diode laser bars and beam forming systems with micro-optics have led to new direct diode laser applications. LIMO presents 400W output from a 200μm core fibre with an NA of 0.22 at one wavelength. This is achieved via the combination of newly designed laser diode bars on passive heat sinks coupled with optimized micro-optical beam shaping. The laser is water cooled with a housing size of 375mm x 265mm x 70mm. The applications for such diode laser modules are mainly in direct marking, cutting and welding of metals and other materials, but improved pumping of fibre lasers and amplifiers is also possible. The small spot size leads to extremely high intensities and therefore high welding speeds in cw operation. For comparison: The M² of the fibre output is 70, which gives a comparable beam parameter product (22mm*mrad) to that of a CO₂ laser with a M² of 7 because of the wavelength difference. Many metals have a good absorption within the wavelength range of the laser diodes (NIR, 808nm to 980nm), which permits the cutting of thin sheets of aluminium or steel with a 200W version of this laser. First welding tests show reduced splatters and pores owing to the optimized process behaviour in cw operation with short wavelengths. The availability of a top-hat profile proves itself to be advantageous compared to the traditional Gaussian beam profiles of fibre, solid-state and gas lasers in that the laser energy is evenly distributed over the working area. For the future, we can announce an increase of the output power up to 1200W out of a 200μm fibre (0.22 NA). This will be achieved by further sophistication and optimisation of the coupling technique and the coupling of three wavelengths. The beam parameter product will then remain at 22mm*mrad with a power density of 3.8 MW/cm² if focussed to a 200µm spot. This leads to excellent laser cutting results with extremely small cutting kerfs down to 200μm and very plane cutting edges. Process speeds rise up to more than 10m/min i.e. for thin sheets of stainless steel or titanium.

Proceedings Article | 13 February 2008 Paper

Fiber-coupled air-cooled high-power diode laser systems

Daniel Bartoschewski, Jens Meinschien, Udo Fornahl

Proceedings Volume 6876, 68761M (2008) https://doi.org/10.1117/12.763199

KEYWORDS: Semiconductor lasers, Laser systems engineering, High power lasers, Diodes, Surgery, Continuous wave operation, Micro optics, Near field optics, Fiber coupled lasers, Resistance

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Current laser systems based on high-power laser diode bars need active cooling either water cooling or the use of thermo-electric coolers to ensure an adequate operating temperature for a reasonable lifetime. Here is a solution with a bonded fin heat sink and forced ventilation introduced, a diode laser bar with an improved efficiency and a low thermal resistance as well as an optical system for a highly efficient fibre coupling. With this system it is possible to couple 25 Watt continuous wave power from a single laser diode bar on a passive heat sink into a fibre with 200 μm core diameter. The basis for this performance is a heat sink with an exceptionally low thermal resistance. Several new features are introduced to reach a low overall gradient between the laser diode temperature and the ambient temperature. In addition, it does geometrically fit to the layout of the optical design. Shape and aspect ratio of both heat sink and housing of the laser system are matched to each other. Another feature is the use of hard-soldered or pressed bars to achieve a thermo-mechanically stable performance. The long-term thermal characteristic was tested. The operation temperature comes to saturation after about 30 minutes. Therefore it can be used for continuous wave operation at 25 Watt output power. At a quasi continuous operation at 70 percent duty cycle a peak power of 30 Watt out of the fibre is possible. From this technology results a compact fibre coupled laser system what is simple to drive compared with current high power laser systems, because there is no need to control the operating temperature. This gives way for more compact driver solutions. Fields of application are laser marking systems and material processing, where a simple driver system is requested. Also medical applications need this requirement and a compact cooling too so that mobile integrated solutions become possible. Further developments allow multiple laser diode systems for specific industrial applications demanding more power. Our measurements show the potential for direct air-cooled laser systems with 100 Watt power out of the fibre.

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