Author
Jian Cheng
Other affiliations: Shandong University, Northeastern University (China), University of Liverpool
Bio: Jian Cheng is an academic researcher from Hubei University of Technology. The author has contributed to research in topics: Materials science & Laser. The author has an hindex of 6, co-authored 19 publications receiving 488 citations. Previous affiliations of Jian Cheng include Shandong University & Northeastern University (China).
Topics: Materials science, Laser, Surface roughness, Composite material, Optics
Papers
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TL;DR: In this paper, a brief review is given regarding ultrafast laser micromachining of materials and some general experimental observations are first provided to show the characteristics of ultrafast LMMM.
Abstract: A brief review is given regarding ultrafast laser micromachining of materials. Some general experimental observations are first provided to show the characteristics of ultrafast laser micromachining. Apart from empirical research, mathematical models also appear to allow for a further and systematic understanding of these phenomena. A few fundamental ultrafast laser micromachining mechanisms are addressed in an attempt to highlight the physics behind the experimental observations and the mathematical models. It is supposed that a vivid view of ultrafast laser micromachining has been presented by linking experimental observations, mathematical models and the behind physics.
322 citations
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TL;DR: In this paper, the diameters, depths and morphologies of the drilled craters were studied and two novel phenomena were found: as hole diameters decreased with fluence, a change of slope of the trend line indicated a change in ablation mechanism for Al and Ti alloy.
Abstract: Picosecond laser single pulse ablation of Au, Al and Ti alloy (Ti6Al4V) was experimentally investigated with a laser pulse width of 10 ps at a wavelength of 1064 nm for potential industrial micromachining applications. The diameters, depths and morphologies of the drilled craters were studied. Two novel phenomena were found: as hole diameters decreased with fluence, a change of slope of the trend line indicated a change in ablation mechanism for Al and Ti alloy, metallic materials with short electron-phonon coupling times (<10 ps), while Au showed no such transition: an isolated island structure was also observed on Au due to significant melt expulsion. A one-dimensional two-temperature model has been used to discriminate different ablation phenomena. It is shown that metallic materials with different electron–phonon coupling constant have different ablation characteristics in the ps regime. This study could be very helpful for metallic material micromachining with high repetition rate ps lasers pulses which indicates that high throughput may be achieved as well as good machining quality.
81 citations
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TL;DR: In this paper, the effects of some key laser operating parameters were investigated for the purpose of industrial application and the evolution of surface morphology revealed that laser pulses overlap in a range around the spatial FWHM can help to achieve optimal residual surface roughness.
64 citations
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TL;DR: In this paper, a high repetition rate femtosecond laser system is combined with a spatial light modulator (SLM) for diffractive multiple beam processing, and the effect of the zero order beam is eliminated by adding a Fresnel zone lens to defocus the undiffracted beam at the processing plane.
44 citations
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TL;DR: In this article, a simplified predictive model based on critical point phase separation (CPPS) theory was proposed for single shot ablation of metallic materials of aluminium, titanium alloy (Ti6Al4V) and gold.
30 citations
Cited by
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12 Mar 2014
TL;DR: In this paper, the effect of reflectivity of the surface, when a pure, monochromatic laser (6) is used, is remedied by the simultaneous application of a relatively shorter wavelength beam (1).
Abstract: In the laser treatment of a workpiece (9), e.g. for surface hardening, melting, alloying, cladding, welding or cutting, the adverse effect of reflectivity of the surface, when a pure, monochromatic laser (6) is used, is remedied by the simultaneous application of a relatively shorter wavelength beam (1). The two beams (1)(5) may be combined by a beam coupler (4) or may reach the workpiece (9) by separate optical paths (not shown). The shorter wavelength beam (1) improves the coupling efficiency of the higher- powered laser beam (5).
1,539 citations
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TL;DR: In this paper, the mechanisms of short pulse laser interactions with a metal target are investigated in simulations performed with a model combining the molecular dynamics method with a continuum description of laser excitation, electron−phonon equilibration, and electron heat conduction.
Abstract: The mechanisms of short pulse laser interactions with a metal target are investigated in simulations performed with a model combining the molecular dynamics method with a continuum description of laser excitation, electron−phonon equilibration, and electron heat conduction. Three regimes of material response to laser irradiation are identified in simulations performed with a 1 ps laser pulse, which corresponds to the condition of stress confinement: melting and resolidification of a surface region of the target, photomechanical spallation of a single or multiple layers or droplets, and an explosive disintegration of an overheated surface layer (phase explosion). The processes of laser melting, spallation, and phase explosion are taking place on the same time scale and are closely intertwined with each other. The transition to the spallation regime results in a reduction of the melting zone and a sharp drop in the duration of the melting and resolidification cycle. The transition from spallation to phase e...
398 citations
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TL;DR: In this paper, a brief review is given regarding ultrafast laser micromachining of materials and some general experimental observations are first provided to show the characteristics of ultrafast LMMM.
Abstract: A brief review is given regarding ultrafast laser micromachining of materials. Some general experimental observations are first provided to show the characteristics of ultrafast laser micromachining. Apart from empirical research, mathematical models also appear to allow for a further and systematic understanding of these phenomena. A few fundamental ultrafast laser micromachining mechanisms are addressed in an attempt to highlight the physics behind the experimental observations and the mathematical models. It is supposed that a vivid view of ultrafast laser micromachining has been presented by linking experimental observations, mathematical models and the behind physics.
322 citations
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TL;DR: The authors’ experimental work on laser-inscribed regular pattern fabrication is presented to give a complete picture of micromachining processes and a guideline for surface structures optimization is provided.
Abstract: Femtosecond laser micromachining has emerged in recent years as a new technique for micro/nano structure fabrication because of its applicability to virtually all kinds of materials in an easy one-step process that is scalable. In the past, much research on femtosecond laser micromachining was carried out to understand the complex ablation mechanism, whereas recent works are mostly concerned with the fabrication of surface structures because of their numerous possible applications. The state-of-the-art knowledge on the fabrication of these structures on metals with direct femtosecond laser micromachining is reviewed in this article. The effect of various parameters, such as fluence, number of pulses, laser beam polarization, wavelength, incident angle, scan velocity, number of scans, and environment, on the formation of different structures is discussed in detail wherever possible. Furthermore, a guideline for surface structures optimization is provided. The authors’ experimental work on laser-inscribed regular pattern fabrication is presented to give a complete picture of micromachining processes. Finally, possible applications of laser-machined surface structures in different fields are briefly reviewed.
295 citations
01 May 2013
TL;DR: The Solid State Solar-Thermal Energy Conversion Center (SSEEC) as discussed by the authors is a solid-state solar-thermal energy conversion center at the U.S. Dept. of Energy.
Abstract: United States. Dept. of Energy. Office of Basic Energy Sciences (Solid-State Solar-Thermal Energy Conversion Center)
292 citations