Femtosecond laser single step, full depth cutting of thick silicon sheets with low surface roughness

2021 ◽  
Vol 138 ◽  
pp. 106899
Author(s):  
Zhaoqing Li ◽  
Olivier Allegre ◽  
Qianliang Li ◽  
Wei Guo ◽  
Lin Li
Keyword(s):  
Surface Roughness ◽  
Femtosecond Laser ◽  
Single Step

scholarly journals Synthesis of Nanotips Through Femtosecond Laser Ablation of Glass with Assisted Gas

2021 ◽  
Author(s):  
Nikunj Patel
Keyword(s):  
Femtosecond Laser ◽  
Building Materials ◽  
High Vacuum ◽  
Synthesis Method ◽  
Femtosecond Laser Ablation ◽  
Target Surface ◽  
Laser Pulses ◽  
Single Step ◽  
Femtosecond Laser Irradiation ◽  
Ambient Conditions

Nanotips are the key nanostructures for many applications. Until now, the nanotips of only the crystalline materials have been produced via various deposition methods which require sophisticated equipment, high vacuum, and clean room operations. This thesis proposes a single step, rapid synthesis method using femtosecond laser irradiation at megahertz frequency with background flow of nitrogen gas at ambient conditions. Amorphous nanotips are obtained without the use of catalyst. The nanotips grow from highly energetic plasma generated when target is irradiated with laser pulses. The vapor condensates, nanoparticles and droplets from the plasma get deposited back on to the hot target surface where they experience force imbalance due to which the stems for the nanotips growth are initiated. Once the stems are generated, the continuous deposition of vapor condensates [sic] provides building materials to the stems to complete the growth of nanotips. Further study found that the growth of the nanotips is influenced by laser parameters and gas conditions.

scholarly journals Femtosecond Laser Fabrication of Engineered Functional Surfaces based on Biodegradable Polymer and Biopolymer/Ceramic Composite Thin Films

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 378 ◽  
Author(s):  
Albena Daskalova ◽  
Irina Bliznakova ◽  
Liliya Angelova ◽  
Anton Trifonov ◽  
Heidi Declercq ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Femtosecond Laser ◽  
Surface Functionalization ◽  
Biodegradable Polymer ◽  
Photoelectron Spectroscopy ◽  
Laser Energy ◽  
Surface Characteristics ◽  
Laser Pulses ◽  
Xrd Analysis

Surface functionalization introduced by precisely-defined surface structures depended on the surface texture and quality. Laser treatment is an advanced, non-contact technique for improving the biomaterials surface characteristics. In this study, femtosecond laser modification was applied to fabricate diverse structures on biodegradable polymer thin films and their ceramic blends. The influences of key laser processing parameters like laser energy and a number of applied laser pulses (N) over laser-treated surfaces were investigated. The modification of surface roughness was determined by atomic force microscopy (AFM). The surface roughness (Rrms) increased from approximately 0.5 to nearly 3 µm. The roughness changed with increasing laser energy and a number of applied laser pulses (N). The induced morphologies with different laser parameters were compared via Scanning electron microscopy (SEM) and confocal microscopy analysis. The chemical composition of exposed surfaces was examined by FTIR, X-ray photoelectron spectroscopy (XPS), and XRD analysis. This work illustrates the capacity of the laser microstructuring method for surface functionalization with possible applications in improvement of cellular attachment and orientation. Cells exhibited an extended shape along laser-modified surface zones compared to non-structured areas and demonstrated parallel alignment to the created structures. We examined laser-material interaction, microstructural outgrowth, and surface-treatment effect. By comparing the experimental results, it can be summarized that considerable processing quality can be obtained with femtosecond laser structuring.

Characterization of Electrical Contacts on Silicon (100) after Ablation and Sulfur Doping by Femtosecond Laser Pulses

2013 ◽  
Vol 205-206 ◽  
pp. 358-363 ◽  
Author(s):  
Philipp Saring ◽  
Anna Lena Baumann ◽  
Stefan Kontermann ◽  
Wolfgang Schade ◽  
Michael Seibt
Keyword(s):  
Surface Roughness ◽  
Femtosecond Laser ◽  
Laser Pulses ◽  
Sample Surface ◽  
Femtosecond Laser Pulses ◽  
Electrical Contacts ◽  
Single Shot ◽  
Excess Charge ◽  
Silicon Sample ◽  
Etching Depth

This paper investigates the influence of different number of laser pulses on contact behavior and conductivity of the surface layer of femtosecond laser microstructured, sulfur-doped silicon. Single shot laser processed silicon (Pink Silicon) is characterized by low surface roughness, whereas five shot laser processed silicon (Grey Silicon) has an elevated sulfur content with a surface roughness low enough to maintain good contacting. To laterally confine the laser induced pn-junction part of the Grey Silicon sample surface is etched off. The etching depth is confirmed to be sufficient to completely remove the active n-type sulfur layer. While Pink Silicon shows little or no lateral conductivity within the laser processed layer, Grey Silicon offers acceptable conductivity, just as expected by the fact of having incorporated a higher sulfur dopant content. Recombination dominates the irradiated regions of Pink Silicon and suppresses excess charge carrier collection. Grey Silicon, while showing sufficient lateral conductivity, still shows regions of lower conductivity, most likely dominated by the laser irradiation-induced formation of dislocations. According to our results, the optimum laser pulse number for electrical and structural properties is expected to be in the range between one and five laser pulses.

Superstructure Fiber Gratings Via Single Step Femtosecond Laser Inscription

2012 ◽  
Vol 30 (8) ◽  
pp. 1229-1236 ◽  
Author(s):  
C. Koutsides ◽  
E. Davies ◽  
K. Kalli ◽  
M. Komodromos ◽  
T. Allsop ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Single Step ◽  
Fiber Gratings

Honed surface multi-scale Prediction based on multi-stage honing process of engine cylinder bore

2019 ◽  
pp. 1-32
Author(s):  
Zaoyang Zhou ◽  
Xueping Zhang ◽  
Kunlun Lv ◽  
Jun Wu ◽  
Zhenqiang Yao ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Texture ◽  
Time Discretization ◽  
Single Step ◽  
Analytical Methodology ◽  
Duration Time ◽  
Engine Cylinder ◽  
Two Stages ◽  
Cylinder Bore ◽  
Abrasive Size

Abstract Sequential honing process is usually implemented in engine cylinder bore processing to obtain the cross-hatched surface texture with excellent function to balance lubricant storage capacities and supporting performance. Many researches have devoted to correlating honed surface quality of cylinder bore with honing process parameters by means of experiments or simulations. Quite a few efforts have addressed the effect of sequential multiple steps on the surface texture in the honing of engine cylinder bore. However, these researches cannot provide an explicit and analytical methodology to predict honed surface texture efficiently and accurately. This paper presents an analytical and explicit methodology to incorporate a proposed microscale abrasive model into the analytical simulation process of sequential honing. The proposed abrasive model synthetically considers the shape, size, posture, and position of abrasives randomly distributed in honing stone, which is incorporated into honing head motions in terms of rotation, oscillation and feeding. The kinematics of honing head is calculated by space-time discretization to capture the interaction between honing stones and cylinder bore surface. The above procedure acts as each single step for the sequential honing processes. This study investigates the sequential honing of two stages including semi-finish honing and plateau honing at different feeding speeds by applying the abrasive model with different abrasive sizes. The formation of cross-hatched surface texture was successfully achieved sequentially by semi-finish honing and plateaus honing. Then the Abbott-Firestone Curve of the honed surface can be obtained to analyze the influences of abrasive size and honing time of two stages on the surface roughness. Correctness of surface roughness predicted by the model is verified by comparing with a group of experiment measurements in terms of Abbott-Firestone Curve. Most errors of all the predicted Rk roughness family roughness parameters in the two honing stages are less than 15%. Based on the model, simulations are done to analyze the influences of abrasive size and honing duration time of two stages on the surface roughness. The result shows that the larger abrasive used in finish honing leads to the decrease of the material portions Mr1, Mr2 and the increase of the reduced valley depth Rvk. The longer plateau honing duration time is preferred to produce the larger Mr1, Mr2 and the smaller Rvk.

Simulating the Sequential Honing Process of Engine Cylinder Bore by Modeling Abrasives in Honing Stone

2019 ◽  
Author(s):  
Zaoyang Zhou ◽  
Xueping Zhang ◽  
Kunlun Lv ◽  
Jun Wu ◽  
Zhenqiang Yao ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Texture ◽  
Time Discretization ◽  
Single Step ◽  
Analytical Methodology ◽  
Duration Time ◽  
Engine Cylinder ◽  
Two Stages ◽  
Cylinder Bore ◽  
Abrasive Size

Abstract Sequential honing process is usually implemented in engine cylinder bore processing to obtain the cross-hatched surface texture with excellent function to balance lubricant storage capacities and supporting performance. Many researches have devoted to correlating honed surface quality of cylinder bore with honing process parameters by means of experiments or simulations. Quite a few efforts have addressed the effect of sequential multiple steps on the surface texture in the honing of engine cylinder bore. However, these researches cannot provide an explicit and analytical methodology to predict honed surface texture efficiently and accurately. This paper presents an analytical and explicit methodology to incorporate a proposed microscale abrasive model into the analytical simulation process of sequential honing. The proposed abrasive model synthetically considers the shape, size, posture, and position of abrasives randomly distributed in honing stone, which is incorporated into honing head motions in terms of rotation, oscillation and feeding. The kinematics of honing head is calculated by space-time discretization to capture the interaction between honing stones and cylinder bore surface. The above procedure acts as each single step for the sequential honing processes. This study investigates the sequential honing of two stages including semi-finish honing and plateau honing at different feeding speeds by applying the abrasive model with different abrasive sizes. The formation of cross-hatched surface texture was successfully achieved sequentially by semi-finish honing and plateaus honing. Then the Abbott-Firestone Curve of the honed surface can be obtained to analyze the influences of abrasive size and honing time of two stages on the surface roughness. Correctness of surface roughness predicted by the model is verified by comparing with a group of experiment measurements in terms of Abbott-Firestone Curve. Most errors of all the predicted Rk roughness family roughness parameters in the two honing stages are less than 15%. Based on the model, simulations are done to analyze the influences of abrasive size and honing duration time of two stages on the surface roughness. The result shows that the larger abrasive used in finish honing leads to the decrease of the material portions Mr1, Mr2 and the increase of the reduced valley depth Rvk. The longer plateau honing duration time is preferred to produce the larger Mr1, Mr2 and the smaller Rvk.

scholarly journals Micromachining of Transparent Biocompatible Polymers Applied in Medicine Using Bursts of Femtosecond Laser Pulses

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1093
Author(s):  
Evaldas Kažukauskas ◽  
Simas Butkus ◽  
Piotr Tokarski ◽  
Vytautas Jukna ◽  
Martynas Barkauskas ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Femtosecond Laser ◽  
Contact Lenses ◽  
Laser Pulses ◽  
Laser Micromachining ◽  
Femtosecond Laser Pulses ◽  
Intraocular Lenses ◽  
Great Promise ◽  
Biocompatible Polymers ◽  
Mechanical Methods

Biocompatible polymers are used for many different purposes (catheters, artificial heart components, dentistry products, etc.). An important field for biocompatible polymers is the production of vision implants known as intraocular lenses or custom-shape contact lenses. Typically, curved surfaces are manufactured by mechanical means such as milling, turning or lathe cutting. The 2.5 D objects/surfaces can also be manufactured by means of laser micromachining; however, due to the nature of light–matter interaction, it is difficult to produce a surface finish with surface roughness values lower than ~1 µm Ra. Therefore, laser micromachining alone can’t produce the final parts with optical-grade quality. Laser machined surfaces may be polished via mechanical methods; however, the process may take up to several days, which makes the production of implants economically challenging. The aim of this study is the investigation of the polishing capabilities of rough (~1 µm Ra) hydrophilic acrylic surfaces using bursts of femtosecond laser pulses. By changing different laser parameters, it was possible to find a regime where the surface roughness can be minimized to 18 nm Ra, while the polishing of the entire part takes a matter of seconds. The produced surface demonstrates a transparent appearance and the process shows great promise towards commercial fabrication of low surface roughness custom-shape optics.

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