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Microstructures Manufactured in Diamond by Use of Laser Micromachining
摘要： Different microstructures were created on the surface of a polycrystalline diamond plate (obtained by microwave plasma-enhanced chemical vapor deposition—MW PECVD process) by use of a nanosecond pulsed DPSS (diode pumped solid state) laser with a 355 nm wavelength and a galvanometer scanning system. Different average powers (5 to 11 W), scanning speeds (50 to 400 mm/s) and scan line spacings (“hatch spacing”) (5 to 20 μm) were applied. The microstructures were then examined using scanning electron microscopy, confocal microscopy and Raman spectroscopy techniques. Microstructures exhibiting excellent geometry were obtained. The precise geometries of the microstructures, exhibiting good perpendicularity, deep channels and smooth surfaces show that the laser microprocessing can be applied in manufacturing diamond microfluidic devices. Raman spectra show small differences depending on the process parameters used. In some cases, the diamond band (at 1332 cm?1) after laser modification of material is only slightly wider and shifted, but with no additional peaks, indicating that the diamond is almost not changed after laser interaction. Some parameters did show that the modification of material had occurred and additional peaks in Raman spectra (typical for low-quality chemical vapor deposition CVD diamond) appeared, indicating the growing disorder of material or manufacturing of the new carbon phase.
关键词： laser microprocessing,polycrystalline diamond,microstructures
更新于2025-09-23 15:19:57
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Sub-micron structuring/texturing of diamond-like carbon-coated replication masters with a femtosecond laser
摘要： Diamond-like carbon (DLC) coatings have very attractive mechanical and tribological properties, i.e. high hardness, low friction and high wear resistance. Therefore, DLC is often used as a solid lubricant in moulds for injection moulding. Laser processing of DLC with ultrashort lasers, i.e. femtosecond lasers, can be performed both at micron and sub-micron scales, namely by producing laser-induced periodic surface structures (LIPSS). In this research, the effects of laser structuring/texturing on DLC properties are investigated. First, the laser-processing parameters were optimised to produce uniform LIPSS without damaging a thin DLC film and then the properties of the textured DLC-coated substrates were studied. It was determined that the tribological properties of the processed surfaces remained unchanged, but the hardness of the structured/textured DLC layers was reduced significantly. Although GAXRD and Raman spectroscopy did not show any significant crystallisation of the DLC coating after the laser irradiation, the analysis indicated that a thin graphitised layer had been formed on the surface as a result of the femtosecond laser processing.
关键词： Laser microprocessing,Femtosecond laser,LIPSS,Diamond-like carbon (DLC)
更新于2025-09-19 17:13:59
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[Laser Institute of America ICALEO?? 2017: 36th International Congress on Applications of Lasers & Electro-Optics - Atlanta, Georgia, USA (October 22a??26, 2017)] International Congress on Applications of Lasers & Electro-Optics - Aberration control by high NA focusing in transparent media
摘要： High numerical aperture (NA) focusing of light in transparent media is important in microscopy, various techniques of optical data storage and laser microprocessing. By high NA focusing through a flat bounding surface of a medium there appears positive spherical aberration reducing energy concentration and lowering physical resolution. The deeper is focusing and higher NA, the stronger is aberration and light scattering. By laser material processing there appears uncontrolled energy distribution along optical axis that makes inherently complex physical processes of laser radiation interaction with material even more complex and less predictable. To control the spherical aberration induced by internal high NA focusing it is suggested to apply specially designed aplanatic objective of patent pending optical design. The objective provides full compensation of spherical aberration for diffraction limited on-axis and off-axis high NA focusing at wide range of depths, for example from 0 to 2 mm in fused silica for NA0.8 without immersion. By setting movable components in optimum for particular depth reciprocal positions it is possible to provide not only full aberration compensation but also under- and over-compensation, thus providing control of energy distribution along optical axis at arbitrary depth and achieving special material processing effects. The paper describes design features of this optical approach as well as comparative results of spot size calculations and corresponding microphotographs of processed areas in fused silica by laser radiation focusing at various depths using NA0.8 objectives with and without compensation of aberrations.
关键词： aplanatic objective,spherical aberration,laser microprocessing,high numerical aperture,transparent media
更新于2025-09-19 17:13:59
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From PV to bio: Surviving the photovoltaic bubble at laser centre UPM
摘要： Laser Centre UPM is one of the leading Research Centers in Spain in the field of industrial applications of high power lasers. Founded in 1998 in the oldest and largest Spanish Technical University, Universidad Politécnica de Madrid, its activity is focused in technological transfer of laser-based processes to industry. With an important experience in laser micromachining using fast and ultrafast lasers, one of the fields in which its activity has produced more relevant results is laser process development for photovoltaic (PV) industry. Starting in 2004, its activity in this field in collaboration with other public Spanish institutions and other industrial partners has had a remarkable scientific and technological impact. Unfortunately, this activity was seriously restricted since 2010 due to the economic crisis in general and the photovoltaic industry evolution in particular. However, the background acquired in some particular applications and the inertia obtained with that activity has opened new fields of activity of Laser Center UPM in advanced laser-based processes for biomedicine. This paper summarizes the main achievements of Laser Center UPM in PV and how it performed the transition to new applications in a completely different sector, like biomedicine, using the experienced accumulated in the development of new laser based processes for PV.
关键词： metallization,laser bioprinting,LIFT,laser microprocessing,silicon photovoltaics
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Generation of Vector Bessel Beams and their Application for Laser Microprocessing of Transparent Materials
摘要： Bessel beams are perfect candidates for laser microprocessing of transparent materials due to generation of high aspect ratio micro voids [1], and ability to control micro crack formation enables to efficiently cut them [2, 3]. The crack propagation direction is controlled by inducing asymmetry to beam profile [3], and allows ultra-fast glass cutting over non-straight lines. The laser-matter interaction of various nondiffracting beams is heavily investigated and their utilisation for laser microprocessing is soon to be expected. Vector beams that are more exotic than scalar counterparts and can have additional beneficial properties for micro-manufacturing of materials. For instance, vector Bessel beam has a doughnut shaped intensity profile with complex spatial distribution of polarisation and can be de-composed to two transverse polarisation intensity components [4]. In this work, we examine generation of vector Bessel beams using an axicon and an s-plate (Workshop of photonics) – radial polarization converter [5]. The s-plate allows generation of azimuthally or radially polarized beams while axicon converts it to nondifftracting Bessel vector beam. The polariser was used to separate its orthogonal polarisation components (Fig. 1). The proposed approach to generate these beams is beneficial for high energy beam systems because s-plate withstands ultrashort (fs-ps) high power pulses. To investigate their applicability to transparent material micro-fabrication we performed microprocessing of a glass with vector Bessel beams and were able to induce high aspect ratio volume modifications and micro cracks in transparent materials. Vector Bessel beams produces cylinder shaped material modifications of glass (Fig 2 a)) while the use of single polarisation component generates two parallel needle like material modification (Fig. 2 b)). By elongating the pulse duration to few ps we have observed micro crack formation extending perpendicular to the beam propagation direction and to two intensity peaks. (Fig. 2 c)). The produced modifications are investigated to increase the laser microprocessing quality and speed.
关键词： Bessel beams,laser microprocessing,transparent materials,axicon,vector beams,s-plate
更新于2025-09-12 10:27:22