Refractive Beam Shaping Optics Research Articles

Enlarging the process window in absorber-free laser transmission welding of polymer foils using tailored laser intensity distribution

Absorber-free laser transmission welding enables precise and clean joining of polymer foils without absorbent additives or adhesives. It is well suited for applications in medical technology and food industry, which impose high demands on process reliability. To achieve a large process window and thus a reliable process, a homogeneous weld seam temperature is desirable. For this purpose, the intensity distribution of the laser beam is adapted locally by refractive beam shaping optics. Using a donut-shaped intensity distribution, the weld seam temperature is homogenized. Thus, the process window for welding polypropylene or polyethylene foils is enlarged up to a factor of 4 compared to a conventional, Gaussian-shaped distribution. This enables the reliable welding of even 85 µm thin foils, which could only be welded to a limited extent with a conventional laser intensity distribution.

Refractive and diffractive laser beam shaping optics

AbstractEspecially for micro machining lasers have opened new possibilities which were not accessible by traditional mechanical processes (e.g. intravolume glass marking). For many applications the raw Gaussian laser beam profiles are not optimal adapted for material processing. Therefore optimized beam profiles like those with homogeneous intensity (so called Top Hat) or with ring shape are often desired to enhance process efficiency and quality.

πShaper – Refractive Beam Shaping Optics for Advanced Laser Technologies

Laser beam shaping brings to various industrial and scientific laser techniques effects that improve their performance comparing to what can be achieved with using Gaussian or Gaussian-like laser beams: more stability, less tough positioning tolerances make the technologies easier to use, higher efficiency of using of costly laser energy, etc. The task of such a transformation is solved by series of refractive beam shaping optics of field mapping type. This solution is important in irradiating the cathode of Free Electron Lasers, confocal microscopy, biomedical fluorescence techniques, many industrial technologies like welding, cladding, hardening, various laser techniques in photovoltaics, homogenizing of pump radiation by building powerful femtosecond lasers, etc. The refractive beam shapers can be used with TEM00 and multimode laser beams, achromatic design provides the same conditions of beam shaping for several lasers of a certain spectrum range simultaneously, low inherent losses allow to use them with powerful laser sources, particular models can be implemented as Galilean Telescope without internal focusing or as Collimators. This paper will describe the principles of operation, design features of the achromatic refractive beam shapers; there will be presented examples of beam intensity transformation and effects on material processing achieved in several industrial applications.