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  • 1
    Online Resource
    Online Resource
    Ablation efficiency of high average power ultrafast laser
    Laser Institute of America ; 2015
    In:  Journal of Laser Applications Vol. 27, No. S2 ( 2015-02-01)
    Details
    In: Journal of Laser Applications, Laser Institute of America, Vol. 27, No. S2 ( 2015-02-01)
    Abstract: Nowadays, the relevance of ultrashort laser is well established for many medical or industrial applications. Indeed, the ultrashort laser technology has reached a high level of robustness which makes it compatible with the needs of industry. This laser technology combines the unique capacity to process any type of material with an outstanding precision and a minimal heat affected zone. Thanks to high average power and high repetition rate it is possible to achieve high throughput providing that the operating parameters are finely tuned to the application, otherwise heat accumulation and heat affected zone may appear. In this paper, the authors report on high throughput single pass ablation of stainless steel with a high average power Yb-doped fiber ultrashort pulse laser which is tunable in pulse duration from 350 fs to 10 ps and in repetition rate from 200 kHz to 2 MHz. The influence of pulse duration, repetition rate, fluence, energy dose, and scanning velocity will be discussed in terms of ablation efficiency and processing quality. These results will be compared to those previously obtained on aluminum, copper, and molybdenum. The authors will see that the effect of these parameters is strongly material dependent. The ablation behavior of stainless steel is very sensitive to these parameters meanwhile it is not the case for aluminum in the investigated process window. The authors observe an intermediate behavior for copper and molybdenum. Moreover, the authors will demonstrate that engraving of metals without melt formation is possible even at high average power (20 W) and high repetition rate. Furthermore, best ablation efficiency and quality are obtained at low fluencies. Scaling up from 2 to 15 W implies to use high repetition rate and high deflection velocity.
    Type of Medium: Online Resource
    ISSN: 1042-346X , 1938-1387
    URL: Article
    DOI: 10.2351/1.4906479
    Language: English
    Publisher: Laser Institute of America
    Publication Date: 2015
    detail.hit.zdb_id: 2084611-3
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  • 2
    Online Resource
    Online Resource
    Laser dressing of metal bonded diamond blades for cutting of hard brittle materials
    Laser Institute of America ; 2012
    In:  Journal of Laser Applications Vol. 24, No. 2 ( 2012-05), p. 022002-
    Details
    In: Journal of Laser Applications, Laser Institute of America, Vol. 24, No. 2 ( 2012-05), p. 022002-
    Type of Medium: Online Resource
    ISSN: 1042-346X , 1938-1387
    URL: Article
    DOI: 10.2351/1.3685300
    Language: English
    Publisher: Laser Institute of America
    Publication Date: 2012
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  • 3
    Online Resource
    Online Resource
    Optimization of surface engraving quality with ultrafast lasers
    Laser Institute of America ; 2017
    In:  Journal of Laser Applications Vol. 29, No. 2 ( 2017-05-01)
    Details
    In: Journal of Laser Applications, Laser Institute of America, Vol. 29, No. 2 ( 2017-05-01)
    Abstract: Large area engraving is achieved by moving a focused femtosecond beam on the sample surface. Of course, the process parameters are the moving speed (moving beam or moving sample or both) and the laser repetition rate. Surface engraving is obtained by multiple linear pass shifted along the y-axis perpendicular to the moving x-axis. The resulting surface shape is thus highly dependent on the deviation Δy between two successive shifted passes. Being able to predict and optimize the process in terms of the depth and surface quality is a key advantage. In this work, we show that experimentally engraved surface shapes can be numerically estimated using a simple ablation model. Only two parameters are needed to have a satisfactory description of the laser matter interaction for a given material. We combine the description of the engraving process with the laser matter interaction model to calculate the surface shape after laser scanning.
    Type of Medium: Online Resource
    ISSN: 1042-346X , 1938-1387
    URL: Article
    DOI: 10.2351/1.4983498
    Language: English
    Publisher: Laser Institute of America
    Publication Date: 2017
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  • 4
    Online Resource
    Online Resource
    Optimizing the processing of sapphire with ultrashort laser pulses
    Laser Institute of America ; 2016
    In:  Journal of Laser Applications Vol. 28, No. 2 ( 2016-05-01)
    Details
    In: Journal of Laser Applications, Laser Institute of America, Vol. 28, No. 2 ( 2016-05-01)
    Abstract: The ability to rapidly and precisely generate high-quality features with small dimensions in sapphire is paramount for broadening its appeal and expanding its utilization for consumer electronics applications. Intrinsic properties of sapphire, including high scratch resistance, make it an attractive option for these purposes, but the ability to machine fine features in sapphire substrates with common mechanical and laser-based methods has proved elusive to this point. In this study, we present results from a series of systematic trials to determine the optimum laser processing parameters for drilling 400 μm diameter holes with no cracks or chips and & lt;5° taper in 430 μm thick sapphire wafers with a 0.8 ps 1030 nm source. Holes are drilled at repetition rates from 21 to 1042 kHz, overlaps from 70% to 98%, and translation of the beam waist through the sample at rates from 10 to 200 μm/s. We present qualitative and quantitative results generated from laser scanning microscopy demonstrating that holes with & lt;5° taper and no cracks or chips can be drilled at repetition rates of 260 kHz with 90% and 95% overlap and 521 kHz with 95% overlap. We find that the optimum processing parameters for drilling holes with & lt;5° taper correlates well with the conditions necessary for avoiding chipping, cracking, and back-side damage rings. Holes with & lt;5° taper can be drilled in as short as 4–6 s per holes, and holes with & lt;2° taper can be drilled in 10–12 s per hole.
    Type of Medium: Online Resource
    ISSN: 1042-346X , 1938-1387
    URL: Article
    DOI: 10.2351/1.4944509
    Language: English
    Publisher: Laser Institute of America
    Publication Date: 2016
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  • 5
    Online Resource
    Online Resource
    Ultrafast laser ablation of transparent conductive silver nanowire thin film on polyethylene terephthalate substrate
    Laser Institute of America ; 2016
    In:  Journal of Laser Applications Vol. 28, No. 2 ( 2016-05-01)
    Details
    In: Journal of Laser Applications, Laser Institute of America, Vol. 28, No. 2 ( 2016-05-01)
    Abstract: In printed electronics, such as organic photovoltaic or organic light-emitting diode display and lighting, a transparent conductive oxide layer has to be designed to delimit the size and shape of the final device. The most commonly used material is indium tin oxide (ITO). ITO has however many downsides such as resource scarcity, expensive processing, and brittleness (especially on flexible substrates). Silver nanowires are a promising alternative to overcome these issues, although optimization is still needed to reach ITO performance in terms of transparency and conductivity. In this study, the laser process has to remove the silver nanowire layer in order to obtain an electrical isolation: no remaining bridges in the scribe due to recast material or incomplete removal can be tolerated. Laser ablation of this transparent conductive thin film deposited on polyethylene terephthalate has been investigated using an ultrafast laser source. Pulse energy and scan speed were varied to determine their influence on depth selectivity and process window. The profiles of the selectively ablated area were studied with optical, confocal, and scanning electron microscopy. Compared to irradiation through the substrate, it was shown that front side irradiation allows a much larger process window. In the latter configuration, a fluence ranging from 0.22 to 15.8 J/cm2 and a scanning speed from 200 to 3000 mm/s, at a fixed frequency of 200 kHz, allowed a clean removal of silver nanowires. Using these parameters, isolated squares were scribed and electrical resistance was measured between the inside and the outside of the squares. A good electrical isolation ( & gt;20 MΩ) proved the successful removal of the silver nanowire layer using picosecond laser pulses, at a wavelength of 532 nm.
    Type of Medium: Online Resource
    ISSN: 1042-346X , 1938-1387
    URL: Article
    DOI: 10.2351/1.4944511
    Language: English
    Publisher: Laser Institute of America
    Publication Date: 2016
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  • 6
    Online Resource
    Online Resource
    Beam engineering strategies for high throughput, precise, micro-cutting by 100 W, femtosecond lasers
    Laser Institute of America ; 2020
    In:  Journal of Laser Applications Vol. 32, No. 4 ( 2020-11-01)
    Details
    In: Journal of Laser Applications, Laser Institute of America, Vol. 32, No. 4 ( 2020-11-01)
    Abstract: The recent availability on the market of industrial, reliable, ultrashort pulse lasers (UPLs) delivering hundreds of watts has opened the possibility for this technology to significantly increase the machining throughput and address an ever-larger number of industrial applications. Nevertheless, heat accumulation phenomena are observed as soon as the average power P exceeds tens of watts, compromising the peculiar UPL machining quality. In this case, for a given machining process, it is determinant to implement a specific beam engineering strategy to mitigate thermal impacts, exploit the available P, and increase the throughput. Here, we show the results obtained in micro-cutting with an IR, femtosecond laser delivering Pmax = 100 W, at a maximum repetition rate of fmax = 10 MHz. The beam is first delivered through an innovative, fast, galvo scanner enabling a maximum speed of 20 m/s. A positive impact of high speed is observed for both the removal efficiency at high fluence and the machining quality at high power. In a second step, the beam is also split into three sub-beams enabling parallel processing. The authors show that, in this way, it is possible to fully exploit P, reduce the time taken by a factor of 10, and keep unchanged machining quality.
    Type of Medium: Online Resource
    ISSN: 1042-346X , 1938-1387
    URL: Article
    DOI: 10.2351/7.0000174
    Language: English
    Publisher: Laser Institute of America
    Publication Date: 2020
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