scholarly journals Optical freeform generation by laser machining and plasma-assisted polishing

2019 ◽  
Vol 215 ◽  
pp. 03003
Author(s):  
Thomas Arnold ◽  
Anne Maiwald ◽  
Georg Böhm ◽  
Martin Erhrhard ◽  
Klaus Zimmer
Keyword(s):  
Dwell Time ◽  
Plasma Jet ◽  
Fused Silica ◽  
Surface Shape ◽  
Laser Machining ◽  
Ablation Process ◽  
Silica Sample ◽  
Laser Ablation Process ◽  
Alternative Approach ◽  
Fs Laser

Tailored optical freeform lenses are required for different applications. Sub-aperture deterministic machining techniques such as plasma jet machining have shown great potential to generate freeform surfaces. However, depending on the required local slopes of the surface shape geometrical limitations occur due to the lateral tool function width. In the paper an alternative approach to fabricate freeform shapes exhibiting steep local slopes is presented. A first step involves a dwell time based fs-laser ablation process to generate the surface contour on a fused silica sample. Since the resulting roughness after laser machining lies in the range of 400 nm RMS which does not match optical requirements a subsequent plasma jet based polishing step is performed where micro-roughness is drastically reduced to values below 0.3 nm RMS.

Rapid Manufacturing of Microwave Circuits on Low-Cost Substrates Using Laser Machining

2013 ◽  
Vol 371 ◽  
pp. 200-204 ◽  
Author(s):  
Mehdi Ghulam ◽  
An Yong Hu ◽  
Jun Gang Miao ◽  
Lorelei Gherman
Keyword(s):  
Laser Ablation ◽  
Low Cost ◽  
Microwave Circuits ◽  
Laser Machining ◽  
Ablation Process ◽  
Promising Alternative ◽  
Laser Ablation Process ◽  
Planar Structures ◽  
Laser Structuring ◽  
Manufacturing Tolerances

Microwave and millimeter wave (MMW) planar structures are sensitive to printed circuit manufacturing tolerances. A promising alternative to the conventional photolithographic fabrication technique is laser structuring. This paper presents the study and the experiments conducted to investigate the possibility of employing low-cost commercially available substrates for microwave and MMW circuits using laser ablation process. At least two of such materials (a) glass reinforced ceramic filled teflon (PTFE) and (b) glass reinforced hydrocarbon have been used to design and fabricate microwave and MMW passive structures such as edge-coupled bandpass filter (BPF) using laser machining. The experimental results exhibit the suitability of glass reinforced hydrocarbon materials for microwave circuits employing laser ablation process. However, it is deduced that the laser ablation process alters the complex permittivity characteristics of the ceramic filled PTFE materials. The measured results of laser ablated passive structures on both materials are presented along with the simulation results.

scholarly journals Machine learning for multi-dimensional optimisation and predictive visualisation of laser machining

2021 ◽  
Author(s):  
Michael D. T. McDonnell ◽  
Daniel Arnaldo ◽  
Etienne Pelletier ◽  
James A. Grant-Jacob ◽  
Matthew Praeger ◽  
...  
Keyword(s):  
Short Pulse ◽  
Surface Texturing ◽  
Laser Surface Texturing ◽  
Laser Machining ◽  
Laser Materials ◽  
Parameter Optimisation ◽  
Short Pulse Laser ◽  
Alternative Approach ◽  
Highly Nonlinear ◽  
Wide Range

AbstractInteractions between light and matter during short-pulse laser materials processing are highly nonlinear, and hence acutely sensitive to laser parameters such as the pulse energy, repetition rate, and number of pulses used. Due to this complexity, simulation approaches based on calculation of the underlying physical principles can often only provide a qualitative understanding of the inter-relationships between these parameters. An alternative approach such as parameter optimisation, often requires a systematic and hence time-consuming experimental exploration over the available parameter space. Here, we apply neural networks for parameter optimisation and for predictive visualisation of expected outcomes in laser surface texturing with blind vias for tribology control applications. Critically, this method greatly reduces the amount of experimental laser machining data that is needed and associated development time, without negatively impacting accuracy or performance. The techniques presented here could be applied in a wide range of fields and have the potential to significantly reduce the time, and the costs associated with laser process optimisation.

Comparison of the laser ablation process on Zn and Ti using pulsed digital holographic interferometry

2010 ◽  
Vol 256 (14) ◽  
pp. 4633-4641 ◽  
Author(s):  
E. Amer ◽  
P. Gren ◽  
A.F.H. Kaplan ◽  
M. Sjödahl ◽  
M. El Shaer
Keyword(s):  
Laser Ablation ◽  
Holographic Interferometry ◽  
Ablation Process ◽  
Laser Ablation Process

An Alternative Approach to Analyzing the Interstitial Decay from the End of Range Damage During Millisecond Annealing

2008 ◽  
Vol 1070 ◽  
Author(s):  
Renata Camillo-Castillo ◽  
Mark E Law ◽  
Kevin S Jones
Keyword(s):  
Annealing Time ◽  
Dwell Time ◽  
Extended Defects ◽  
Temperature Dependent ◽  
Temperature Regimes ◽  
Alternative Approach ◽  
Small Times ◽  
Conventional Annealing ◽  
Kinetics Of ◽  
Anneal Temperature

ABSTRACTFlash-assist Rapid Thermal Processing (RTP) presents an opportunity to investigate annealing time and temperature regimes which were previously not accessible with conventional annealing techniques such as Rapid Thermal Annealing. This provides a unique opportunity to explore the early stages of the End of Range (EOR) damage evolution and also to examine how the damage evolves during the high temperature portion of the temperature profile. However, the nature of the Flash-assist RTP makes it is extremely difficult to reasonably compare it to alternative annealing techniques, largely because the annealing time at a given temperature is dictated by the FWHM of the radiation pulse. The FWHM for current flash tools vary between 0.85 and 1.38 milliseconds, which is three orders of magnitude smaller to that required for a RTA to achieve similar temperatures. Traditionally, the kinetics of the extended defects has been studied by time dependent studies utilizing isothermal anneals; in which specific defect structures could be isolated. The characteristics of Flash-assist RTP do not allow for such investigations in which the EOR defect evolution could be closely tracked with time. Since the annealing time at the target temperature for the Flash-assist RTP is essentially fixed to very small times on the order of milliseconds, isochronal anneals are a logical experimental approach to temperature dependent studies. This fact presents a challenge in the data analysis and comparison. Another feature of Flash-assist RTP which makes the analysis complex is the ramp time relative to the dwell time spent at the peak fRTP temperature. As the flash anneal temperature is increased the total ramp time can exceed the dwell time at the peak temperature, which may play a significantly larger role in dictating the final material properties. The inherent characteristics of Flash-assist RTP have consequently required the development of another approach to analyzing the attainable experimental data, such that a meaningful comparison could be made to past studies. The adopted analysis entails the selection of a reference anneal, from which the decay in the trapped interstitial density can be tracked with the flash anneal temperature, allowing for the kinetics of the interstitial decay to be extracted.

scholarly journals Micropatterning on Biodegradable Nanofiber Scaffolds by Femtosecond Laser Ablation Process

2016 ◽  
Vol 49 (6) ◽  
pp. 555-559
Author(s):  
Yongwoo Chung ◽  
Indong Jun ◽  
Yu-Chan Kim ◽  
Hyun-Kwang Seok ◽  
Seok Chung ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Femtosecond Laser Ablation ◽  
Ablation Process ◽  
Laser Ablation Process ◽  
Nanofiber Scaffolds
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