Laserscribing of Thin Films Using Top-Hat Laser Beam Profiles

Rung, Stefan

doi:10.2961/jlmn.2013.03.0021

Cited by 20 publications

(12 citation statements)

References 3 publications

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“…A beam that is shaped with FBS alters its beam profile during propagation. The diffraction-limited Top-Hat beam profile only appears at the focal position [4]. Hence, it is necessary to keep the distance between the focus lens and the machined material constant.…”

Section: Variation Of the Focal Positonmentioning

confidence: 99%

“…For thin film ablation with pulsed nanosecond lasers, the advantages of a spatially-optimized laser beam profile have been demonstrated in many studies [1][2][3][4][5]. In comparison to the common Gaussian beam profile with a circular footprint of Q-switched diode pumped solid state lasers (DPSSL), the use of a Top-Hat laser beam profile with a rectangular footprint provides several benefits for laser ablation of thin films (cf.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of Laser Beam Shaping Optics Based on Their Ablation Geometry of Thin Films

2014

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Thin film ablation with pulsed nanosecond lasers can benefit from the use of beam shaping optics to transform the Gaussian beam profile with a circular footprint into a Top-Hat beam profile with a rectangular footprint. In general, the quality of the transformed beam profile depends strongly on the beam alignment of the entire laser system. In particular, the adjustment of the beam shaping element is of upmost importance. For an appropriate alignment of the beam shaper, it is generally necessary to observe the intensity distribution near the focal position of the applied focusing optics. Systems with a low numerical aperture (NA) can commonly be qualified by means of laser beam profilers, such as a charge-coupled device (CCD) camera. However, laser systems for micromachining typically employ focus lenses with a high NA, which generate focal spot sizes of only several microns in diameter. This turns out to be a challenge for common beam profiling measurement systems and complicates the adjustment of the beam shaper strongly. In this contribution, we evaluate the quality of a Top-Hat beam profiling element and its alignment in the working area based on the ablated geometry of single pulse ablation of thin transparent conductive oxides. To determine the best achievable adjustment, we develop a quality index for rectangular laser ablation spots and investigate the influences of different alignment parameters, which can affect the intensity distribution of a Top-Hat laser beam profile.

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Section: Variation Of the Focal Positonmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterization of Laser Beam Shaping Optics Based on Their Ablation Geometry of Thin Films

2014

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“…Their research has shown a significant improvement in holes' quality, especially in drilling brass plates compared to a conventional Gaussian profile. In another investigation, a square top-hat beam was used to scribe 150 nm thin films of indium tin oxide using both refractive and diffractive beam shapers [42,43]. The uniform energy profile of the square top-hat beam allowed for a smaller pulse overlap to be used and this led to nine-fold increase in the scribing speed compared to Gaussian beam processing while achieving a similar quality.…”

Section: Application Of Top-hat Beams In Laser Micro-machiningmentioning

confidence: 99%

Effects of Top-hat Laser Beam Processing and Scanning Strategies in Laser Micro-Structuring

Penchev

Henrottin³

et al. 2020

Micromachines

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The uniform energy distribution of top-hat laser beams is a very attractive property that can offer some advantages compared to Gaussian beams. Especially, the desired intensity distribution can be achieved at the laser spot through energy redistribution across the beam spatial profile and, thus, to minimize and even eliminate some inherent shortcomings in laser micro-processing. This paper reports an empirical study that investigates the effects of top-hat beam processing in micro-structuring and compares the results with those obtainable with a conventional Gaussian beam. In particular, a refractive field mapping beam shaper was used to obtain a top-hat profile and the effects of different scanning strategies, pulse energy settings, and accumulated fluence, i.e., hatch and pulse distances, were investigated. In general, the top-hat laser processing led to improvements in surface and structuring quality. Especially, the taper angle was reduced while the surface roughness and edge definition were also improved compared to structures produced with Gaussian beams. A further decrease of the taper angle was achieved by combining hatching with some outlining beam passes. The scanning strategies with only outlining beam passes led to very high ablation rates but in expense of structuring quality. Improvements in surface roughness were obtained with a wide range of pulse energies and pulse and hatch distances when top-hat laser processing was used.

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“…Additionally it can be favorable to convert the rotationally symmetric beam into a square or rectangular shape. 1,2 This reduces the time needed for pulsed laser scribing of lines since the overlap area of pulses can be reduced. Truncation of the beam would be another possibility to get a distribution close to homogeneous but this would lead to a high loss of laser power and unwanted diffraction effects.…”

Section: Introductionmentioning

confidence: 98%

Manufacture of refractive and diffractive beam-shaping elements in higher quantities using glass molding technology

Wolz¹,

Blöcher²,

Dross³

et al. 2015

SPIE Proceedings

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Laser beam shaping elements can be used e.g. for material processing. The results of these processes can be improved when the usually Gaussian profile of the laser is transformed into a top hat profile, which can be circular or rectangular in shape. Another frequently used type of beam-forming devices are beam splitters for parallel processing using only one laser. These types of beam formers can be implemented as diffractive or refractive elements. So far these optics are produced either directly by means of lithography e.g. in glass or in plastic using a hot embossing process or nanoimprint technology..Elements produced in this way have either the disadvantage of high costs or they are limited in temperature range, laser power or wavelength. A newly developed molding process for glass allows the manufacture of larger numbers of optics with reduced cost.The production of molds for refractive top hat beam shaping devices requires very high precision of the applied grinding process. Form deviations below 100 nm are necessary to obtain a homogeneous illumination. Measurements of the surface topography of gauss to top hat beam shaping elements using white light interferometry are presented as well as results of optical measurements of the beam profile using a camera.Continuous diffractive beam shaping elements for beam splitting applications are designed to generate several sub-beams each carrying the same energy. In order to achieve this, form deviations of less than 50 nm are required. Measurements of the surface of a 1 x 5 beam splitter are compared with ideal beam splitter profiles. The resulting beam intensity distribution of a molded element is presented.

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Laserscribing of Thin Films Using Top-Hat Laser Beam Profiles

Cited by 20 publications

References 3 publications

Characterization of Laser Beam Shaping Optics Based on Their Ablation Geometry of Thin Films

Characterization of Laser Beam Shaping Optics Based on Their Ablation Geometry of Thin Films

Effects of Top-hat Laser Beam Processing and Scanning Strategies in Laser Micro-Structuring

Manufacture of refractive and diffractive beam-shaping elements in higher quantities using glass molding technology

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