Low-temperature atmospheric pressure argon plasma treatment and hybrid laser-plasma ablation of barite crown and heavy flint glass

Gerhard, Christoph; Roux, Sophie; Brückner, Stephan; Wieneke, Stephan; Viöl, Wolfgang

doi:10.1364/ao.51.003847

Cited by 23 publications

(23 citation statements)

References 33 publications

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“…Such surface smoothing of optical glasses was already observed in previous work where the same plasma source and treatment procedure was applied to barite crown glass NBaK4 and heavy flint glass SF5. After a plasma treatment duration of 60 seconds, Ra was reduced by 7.8% (N-BaK4) and 59.7% (SF5), respectively [12]. Generally, a reduction in surface roughness comes along with a decrease of the surface contact angle, corresponding to an increase in total surface energy γ s [13].…”

Section: Resultsmentioning

confidence: 98%

“…Second, material removal can be due to the deexcitation of excited argon and metastable argon species and an accompanying energy transfer to the sample surface. Here, the possible underlying effects are electron quenching, twoand three-body collisions with argon atoms and Penning ionisation at the sample surface [12]. The existence of such species in the near-surface area can most likely be assumed due the direct plasma ignition on the substrate based on electron excitation and ion-impact excitation in the plasma sheath close to the sample surface [18] and/or resonant neutralisation.…”

Section: Discussionmentioning

confidence: 99%

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Polishing of optical media by dielectric barrier discharge inert gas plasma at atmospheric pressure

Gerhard

Weihs

Luca

et al. 2013

JEOS:RP

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In this paper, surface smoothing of optical glasses, glass ceramic and sapphire using a low-power dielectric barrier discharge inert gas plasma at atmospheric pressure is presented. For this low temperature treatment method, no vacuum devices or chemicals are required. It is shown that by such plasma treatment the micro roughness and waviness of the investigated polished surfaces were significantly decreased, resulting in a decrease in surface scattering. Further, plasma polishing of lapped fused silica is introduced. Based on simulation results, a plasma physical process is suggested to be the underlying mechanism for initialising the observed smoothing effect.

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Section: Resultsmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Polishing of optical media by dielectric barrier discharge inert gas plasma at atmospheric pressure

Gerhard

Weihs

Luca

et al. 2013

JEOS:RP

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“…The feasibility of such simultaneous plasma-assisted ablation was already shown in previous work where argon was used as process gas [32][33][34]. One has to consider that in this case, the advantage was taken of plasma-physical mechanisms instead of plasma-chemical effects.…”

Section: Discussionmentioning

confidence: 97%

Sequential Atmospheric Pressure Plasma-Assisted Laser Ablation of Photovoltaic Cover Glass for Improved Contour Accuracy

et al. 2014

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Abstract:In this paper, we present sequential atmospheric pressure plasma-assisted laser ablation of photovoltaic cover glass. First, glass samples were plasma pre-treated using a hydrogenous plasma process gas in order to accomplish a modification of the near-surface glass network by a chemical reduction and the implantation of hydrogen. As a result, the transmission at a wavelength of 355 nm was reduced by approximately 2% after plasma treatment duration of 60 min. Further, the surface polarity was increased by approximately 78%, indicating an increase of the near-surface index of refraction. Subsequently to the plasma pre-treatment, the samples were laser ablated applying the above-mentioned laser wavelength of a Nd:YAG nanosecond laser. Compared to untreated samples, a significant decrease of the form error by 45% without any mentionable change in the ablation rate was obtained in the case of pre-treated samples. For comparison, the results and findings are discussed with respect to previous work, where the presented plasma-assisted ablation procedure was applied to optical glasses.

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“…By collisions and the related de-excitation of such argon species, an additional energy deposition in the near-surface region of the substrate is achieved [7,8]. For such a simultaneous process, the focused laser beam is guided coaxially to an APP-beam or APP-jet, respectively.…”

Section: Simultaneous Laser-plasma Ablationmentioning

confidence: 99%

“…It was further shown that a pure argon APP-treatment without applying any laser irradiation allows a surface smoothing of the investigated glasses. After a plasma treatment of 60 seconds in duration, the root mean squared roughness rq was reduced by 18.8 % (N-BaK4) and 64.9 % (SF5), respectively [7]. …”

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confidence: 97%

Plasma Meets Glass

Gerhard¹,

Viöl²,

Kretschmer³

2012

Optik & Photonik

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Due to its particular optical and mechanical properties, fused silica is one of the most relevant materials for the production of optical, opto-mechanical and opto-electrical components and systems. Since such glasses feature a high transmittance in the ultraviolet (UV) spectral range, deep UV-laser irradiation or several hybrid methods are usually applied in laser-based manufacturing of optically operative micro-structures on fused silica substrates. Against this background, the development of novel methods for increasing the UV-absorption temporarily is of great interest for laser scribing of optical gratings, micro optics and integrated optical systems. Here, cost-and energy-efficient plasma treatment techniques at atmospheric pressure offer different approaches that can also be applied to other optical glasses.For enhancing the energy deposition into glass substrate surfaces during laser micro structuring, several techniques are in hand. For example, the application of carbon-based thin films allows increasing the absorption of glasses in the UV-range [1]. Further, UV-absorbent silicon suboxide (SiO x ) can be applied by vacuum deposition and micro structured subsequently. Finally, such structured suboxide layers are oxidised to silicon dioxide (SiO 2 ) [2]. The use of hydrogenous gases at high temperatures also allows a direct modification of near-surface SiO 2 bulk material to SiO x [3]. In this contribution, the generation of silicon suboxide in the near-surface region of fused silica bulk material by introducing a plasma treatment at atmospheric pressure and ambient temperature as well as related effects are presented. Although a plasmainduced chemical modification is strongly dependent on the chemical composition of the particular glass, this method also allows altering near-surface properties of multi component glasses such as crown or flint glasses. Further, several plasma-based methods for enhancing laser ablation of glasses are described. In this context, the influence of the use of inert argon as process gas on the treatment and hybrid ablation of optical glasses is discussed. The plasma modification processAtmospheric pressure plasma (APP) induced modification of fused silica can be achieved by the use of different APP-sources, using forming gas 90/10, a mixture of nitrogen N 2 (90 %) and hydrogen H 2 (10 %), as process gas. By dissociation and ionisation processes, excited and reactive species of N and H are generated within the plasma volume when realising a plasma power density in the range of some tens of mW/mm². As shown by the schematic functional principle in Figure 1, such species can effect a reduction of SiO 2 to oxygen-depleted SiO x by different chemical reactions. CHriSToPH GerHArDGerhard studied precision production engineering in Göttingen and Paris and subsequently worked as product manager for optics and university lecturer in Göttingen. During his following occupation as research associate in Bremen, he extra-occupationally studied Optical Engineering/Photonics. He now works as r...

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Low-temperature atmospheric pressure argon plasma treatment and hybrid laser-plasma ablation of barite crown and heavy flint glass

Cited by 23 publications

References 33 publications

Polishing of optical media by dielectric barrier discharge inert gas plasma at atmospheric pressure

Polishing of optical media by dielectric barrier discharge inert gas plasma at atmospheric pressure

Sequential Atmospheric Pressure Plasma-Assisted Laser Ablation of Photovoltaic Cover Glass for Improved Contour Accuracy

Plasma Meets Glass

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