Effects of Radial and Tangential Polarization in Laser Material Processing

Weber, Rudolf; Michalowski, Andreas; Abdou‐Ahmed, Marwan; Onuseit, Volkher; Rominger, Volker; Kraus, Martin; Graf, Thomas

doi:10.1016/j.phpro.2011.03.004

Cited by 129 publications

(56 citation statements)

References 31 publications

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“…Summarizing the simulations, 15,30 experiments, 13,16 and articles combining experiments and theory, 31,32 the best speed-quality relationship is achieved when the melt front inclination angle provides absorbed energy supporting maximally uniform melt flow in all melt pool regions, with minimal melt accumulation. The relationship between the averaged melt front inclination angle, kerf geometry, and laser beam size governs the averaged fraction of the beam power involved in the cutting process.…”

Section: Laser Beam Shape Position and Distortionmentioning

confidence: 98%

Gas-assisted laser cutting of medium-section metals using spherically aberrated beams

Yurevich

Grimm

Polyakov³

et al. 2015

Opt. Eng

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Abstract. We analyzed the effects of the focal point aberrational offset in optical transport systems for highpower lasers. Transverse and near-axial laser intensity distribution transformations in the presence of both positive and negative spherical aberrations were numerically calculated and experimentally demonstrated for different strengths. We show that spherical aberration yields considerable asymmetry of the focused beam's caustic. Several optical transport systems with identical optical parameters (excluding the noncorrected axial beam spherical aberration) were designed. We examined the effects of the laser intensity profiles produced by these systems on the quality of oxygen-assisted laser cutting of medium-section mild steel. We show that high-quality cuts can be obtained for different shapes of laser intensity distribution. However, the greater the refocusing magnitude introduced by the spherical aberration correction, the more precisely the focal point position must be maintained during the laser cutting process. © The Authors. Published by SPIE under a Creative Commons 1 Introduction Laser cutting of metals and alloys is one of the most commercially valuable laser technology processes. Originating from basic research on laser-matter interaction, 1 the field has significantly developed, now offering a large arsenal of state-of-the-art techniques.2-5 Omitting the energy and resource efficiency issues, 6 the performance of laser cutting can be captured by only two output parameters. These are the cutting speed and kerf quality. Thus, laser cutting optimization reduces to achieving the maximal cutting speed with the best kerf quality. As far as the material separation is concerned, 7 the speed can be dramatically increased. On the other hand, the cutting quality depends on many parameters. The most important and frequently discussed are the kerf geometry (accuracy, width, and taper), the surface quality (cut-edge roughness, striations morphology, and dross and burr inclusions), and the mechanical and metallurgical properties (hardness and strength, heat-affected zone, and oxide layer). 8 The number of parameters dramatically affecting the cutting quality ranges from 25 9 to 75. 4,5 These are nearly evenly divided between the workpiece properties, assist gas parameters, laser machine, and laser beam characteristics. Input-output parameters relationships are mostly nonlinear and exhibit strong interdependence. In this regard, maximal precision is provided by the studies that focus on only one input-output parameter pair. Yet, this "one parameter at one time" approach does not provide complete information on the process as a whole.

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Section: Laser Beam Shape Position and Distortionmentioning

confidence: 98%

Gas-assisted laser cutting of medium-section metals using spherically aberrated beams

Yurevich

Grimm

Polyakov³

et al. 2015

Opt. Eng

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“…For instance, radially polarized beams are advantageous for particle acceleration [10] , particle trapping or guiding [11] , lithography, data storage, resolution-enhanced microscopy [12] , orientation of single molecules, and for optical tweezers [13] . At high powers, the most interesting application is metal processing such as metal sheet cutting [14] or welding [14] , as well as drilling [15] . During the past 30 years different extra-and intra-cavity approaches for the generation of radially and azimuthally polarized beams have been developed and reported by several scientific groups [16 -20] .…”

Section: Generation Of Beams With Radial and Azimuthal Polarizationmentioning

confidence: 99%

Applications of sub-wavelength grating mirrors in high-power lasers

Ahmed¹,

Rumpel²,

Voß³

et al. 2012

Advanced Optical Technologies

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A grating waveguide mirror (GWM) results from the combination of a waveguide and a sub-wavelength grating which lead, for given incidence conditions, to polarization and or wavelength filtering. In the present paper, we report on the application of such elements for the selection of the polarization (linear, radial, or azimuthal) as well as the narrowing, stabilizing and tuning of the emission spectrum of high-power lasers. Using a leaky-mode circular GWM, beams with radial and azimuthal polarization with output powers of up to 275 W and 145 W, respectively, could be extracted from a Yb:YAG thin-disk with optical efficiencies of 52.5 % and 43 % , respectively. In both cases, the GWM was composed of a highly reflective (HR) mirror and a sub-wavelength grating as the end-mirror of the resonator. Using a leakymode linear GWM operating under Littrow condition, beams with linear polarization and a narrow spectral bandwidth were obtained from a Yb:YAG thin-disk laser. In multimode operation, an output power of 325 W was achieved at an optical efficiency of 53.5 % . In near-fundamental mode operation, 110 W was extracted at an optical efficiency of 36.2 % . In this latter case, the spectral bandwidth was measured to be around 25 pm. Moreover, continuous wavelength tuning from 1007 to 1053 nm was demonstrated with our device.

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“…In [4] it is shown in the numerical simulation of the laser cutting process that the radial beam polarization provides better cutting efficiency than the linear or circular ones. [5] reports about the higher speed of the qualitative cutting in the case of the radial polarization, but no data on the surface roughness are given there. In [6], they performed the laser cutting of stainless steel sheets of 2 mm; it was found that the advantage of the radial polarization over the circular one was not in the cutting speed, but in the lower pressure of an assistant gas needed for the qualitative cut.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the effect of the laser beam polarization state on the quality of steel sheet cutting

Голышев

Orishich

Shulyatyev

2017

AIP Conference Proceedings

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Abstract. The paper presents the results of experimental investigation of the effect of the beam polarization on the quality of the oxygen-assisted laser cutting of steel by a СО 2 -laser. Under consideration is the effect of the laser cutting parameters by the beam with the linear polarization on the cut surface roughness. It is founded that the minimal roughness is reached when the electric field vector is perpendicular to the cutting speed vector. It is concluded that the absorbed power distribution imposes the essential influence on the surface quality, and that the radiation heating of side walls is important to have lower roughness. Obtained results enabled to present probable reasons of the worse surface quality of the metals cut by a fiber laser than the ones cut by a СО 2 -laser.

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Effects of Radial and Tangential Polarization in Laser Material Processing

Cited by 129 publications

References 31 publications

Gas-assisted laser cutting of medium-section metals using spherically aberrated beams

Gas-assisted laser cutting of medium-section metals using spherically aberrated beams

Applications of sub-wavelength grating mirrors in high-power lasers

Experimental investigation of the effect of the laser beam polarization state on the quality of steel sheet cutting

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