| 51. |
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| 52. |
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| 53. |
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| 54. |
- Bergström, David, et al.
(författare)
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Nd:YAG laser absorptance of rough metal surfaces
- 2007
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Ingår i: Congress proceedings. - Orlando, Fla : Laser institute of America. - 9780912035888
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Konferensbidrag (refereegranskat)abstract
- The Nd:YLF/Nd:YAG laser absorptance of rough metal surfaces has been investigated using 3D ray tracing simulations on computer-generated Gaussian random rough metal surfaces. The impact of multiple scattering, shadowing and Fresnel-equation based angle dependence on the overall absorption is discussed
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| 55. |
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| 56. |
- Bergström, David, et al.
(författare)
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The absorptance of metal surfaces to Nd:YAG/Nd:YLF laser light
- 2008
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Ingår i: Conference proceedings. - Orlando, Fla. : Laser institute of America. - 9780912035895 ; , s. 375-380
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Konferensbidrag (refereegranskat)abstract
- The absorptance of real metallic engineering surfaces used in Laser Material Processing depends strongly upon the particular surface conditions, including the degree of roughness and oxidation. In this paper the influence of surface topography on Nd:YAG/Nd:YLF laser absorptance has been studied, both experimentally and theoretically, on a set of randomly selected as-received metallic engineering surfaces. The surfaces were sputter-coated with a thin layer of gold to eliminate differences in surface chemistry and oxidation. The absorptance was measured using integrating sphere reflectometry and compared to calculations from 3D ray-tracing simulations of AFM-scanned images of the surfaces. The results have increased the understanding of how surface roughness influences the laser-workpiece coupling efficiency.
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| 57. |
- Bergström, David, et al.
(författare)
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The absorptance of steels to Nd:YLF and Nd:YAG laser light at room temperature
- 2007
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 253:11, s. 5017-5028
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Tidskriftsartikel (refereegranskat)abstract
- The measurement of absorptance is important for the analysis and modelling of laser-material interactions. Unfortunately, most of the absorptance data presently available considers only polished pure metals rather than the commercially available (unpolished, oxidised) alloys, which are actually being processed in manufacturing. This paper presents the results of absorptance measurements carried out at room temperature on as-received engineering grade steels including hot and cold rolled mild steel and stainless steels of various types. The measurements were made using an integrating sphere with an Nd:YLF laser at two wavelengths (1053 and 527 nm, which means that the results are also valid for Nd:YAG radiation at 1064 and 532 nm). The absorptance results obtained differ considerably from existing data for polished, pure metals and should help improve the accuracy of laser-material interaction models. Some clear trends were identified; for all materials studied, the absorptance was considerably higher than the previously published values for the relevant pure metals with polished surfaces. For all 15 samples the absorptance was higher for the green than for the infrared wavelength. No clear trend correlating the absorptance with the roughness was found for mild steel in the roughness range Sa 0.4-5.6 μm. A correlation between absorptance and roughness was noted for stainless steel for Sa values above 1.5 μm.
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| 58. |
- Bergström, David, et al.
(författare)
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The absorption of light by rough metal surfaces - a three-dimensional ray-tracing analysis
- 2008
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 103:10, s. 103515-
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Tidskriftsartikel (refereegranskat)abstract
- The laser absorptance of rough surfaces has been investigated by using Monte Carlo simulations based on three-dimensional (3D) ray tracing. The influence of multiple scattering, shadowing, and the Fresnel-equation based angle dependence is discussed. The 3D results are compared to previously published results from a two-dimensional ray-tracing analysis and the different applications of the two models are explained.
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| 59. |
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| 60. |
- Bergström, David, et al.
(författare)
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The reflectance of steels and non-ferrous alloys to Nd:YAG and Nd:YLF laser light
- 2006
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Ingår i: Peer reviewed conference proceedings. - Orlando, Fla. : Laser institute of America. - 0912035846 ; , s. 140-145
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Konferensbidrag (refereegranskat)abstract
- The measurement of reflectance is important for the analysis and modelling of laser-material interactions. Unfortunately, most of the reflectance data presently available consider only polished pure metals rather than the commercially available (unpolished, oxidised) alloys which are actually being processed. This paper presents the results of reflectance measurements carried out on asreceived engineering grade metals including: hot and cold rolled mild steel, zinc coated mild steel, stainless steel, aluminium alloys, copper and brass. The measurements were made using an integrating sphere with an Nd:YLF laser at two wavelengths (1053 nm and 527 nm). The results obtained differ considerably from existing data for polished, pure metals and should help to improve the accuracy of laser-material interaction models.
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