scholarly journals The challenges of productive materials processing with ultrafast lasers

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Rudolf Weber ◽  
Thomas Graf
Keyword(s):  
Ultrafast Lasers ◽  
Average Power ◽  
Processing System ◽  
Processing Parameters ◽  
Materials Processing ◽  
High Tech ◽  
X Rays ◽  
Heat Accumulation ◽  
Physical Limitations ◽  
Air Breakdown

Abstract Materials processing with ultrafast lasers with pulse durations in the range between about 100 fs and 10 ps enable very promising and emerging high-tech applications. Moreover, the average power of such lasers is steadily increasing; multi kilowatt systems have been demonstrated in laboratories and will be ready for the market in the next few years, allowing a significantly increase in productivity. However, the implementation of ultrafast laser processes in applications is very challenging due to fundamental physical limitations. In this paper, the main limitations will be discussed. These include limitations resulting from the physical material properties such as the ablation depth and the optimal fluence, from processing parameters such as air-breakdown and heat accumulation, from the processing system such as thermal focus shift, and from legal regulations due to the potential emission of soft X-rays.

scholarly journals Process limits for percussion drilling of stainless steel with ultrashort laser pulses at high average powers

2021 ◽  
Vol 128 (1) ◽  
Author(s):  
David Brinkmeier ◽  
Daniel Holder ◽  
André Loescher ◽  
Christoph Röcker ◽  
Daniel J. Förster ◽  
...  
Keyword(s):  
Ultrafast Lasers ◽  
Power Level ◽  
Average Power ◽  
High Volume ◽  
Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Ambient Atmosphere ◽  
Heat Accumulation ◽  
Manufacturing Applications ◽  
Percussion Drilling

AbstractThe availability of commercial ultrafast lasers reaching into the kW power level offers promising potential for high-volume manufacturing applications. Exploiting the available average power is challenging due to process limits imposed by particle shielding, ambient atmosphere breakdown, and heat accumulation effects. We experimentally confirm the validity of a simple thermal model, which can be used for the estimation of a critical heat accumulation threshold for percussion drilling of AISI 304 steel. The limits are summarized in a processing map, which provides selection criteria for process parameters and suitable lasers. The results emphasize the need for process parallelization.

Heat input and accumulation for ultrashort pulse processing with high average power

2018 ◽  
Vol 7 (3) ◽  
pp. 145-155 ◽  
Author(s):  
Johannes Finger ◽  
Benedikt Bornschlegel ◽  
Martin Reininghaus ◽  
Andreas Dohrn ◽  
Markus Nießen ◽  
...  
Keyword(s):  
Laser Radiation ◽  
Heat Input ◽  
Ultrashort Pulse ◽  
Average Power ◽  
High Repetition Rate ◽  
Materials Processing ◽  
Heat Accumulation ◽  
Absorbed Energy ◽  
Pulse Processing ◽  
Ultrashort Laser

Abstract Materials processing using ultrashort pulsed laser radiation with pulse durations <10 ps is known to enable very precise processing with negligible thermal load. However, even for the application of picosecond and femtosecond laser radiation, not the full amount of the absorbed energy is converted into ablation products and a distinct fraction of the absorbed energy remains as residual heat in the processed workpiece. For low average power and power densities, this heat is usually not relevant for the processing results and dissipates into the workpiece. In contrast, when higher average powers and repetition rates are applied to increase the throughput and upscale ultrashort pulse processing, this heat input becomes relevant and significantly affects the achieved processing results. In this paper, we outline the relevance of heat input for ultrashort pulse processing, starting with the heat input of a single ultrashort laser pulse. Heat accumulation during ultrashort pulse processing with high repetition rate is discussed as well as heat accumulation for materials processing using pulse bursts. In addition, the relevance of heat accumulation with multiple scanning passes and processing with multiple laser spots is shown.

scholarly journals Throughput scaling by spatial beam shaping and dynamic focusing

2021 ◽  
Author(s):  
Malte Kumkar ◽  
Myriam Kaiser ◽  
Jonas Kleiner ◽  
Daniel Flamm ◽  
Daniel Günther Grossmann ◽  
...  
Keyword(s):  
High Power ◽  
Ultrafast Lasers ◽  
Process Development ◽  
Short Pulse ◽  
Processing Parameters ◽  
In Situ Stress ◽  
Beam Shaping ◽  
Heat Accumulation ◽  
Transparent Materials

With availability of high power ultra short pulsed lasers, one prerequisite towards throughput scaling demanded for industrial ultrafast laser processing was recently achieved. We will present different scaling approaches for ultrafast machining, including raster and vector based concepts. The main attention is on beam shaping for enlarged, tailored processed volume per pulse. Some aspects on vector based machining using beam shaping are discussed. With engraving of steel and full thickness modification of transparent materials, two different approaches for throughput scaling by confined interaction volume, avoiding detrimental heat accumulation, are exemplified. In Contrast, welding of transparent materials based on nonlinear absorption benefits from ultra short pulse processing in heat accumulation regime. Results on in-situ stress birefringence microscopy demonstrate the complex interplay of processing parameters on heat accumulation. With respect to process development, the potential of in-in-situ diagnostics, extended to high power ultrafast lasers and diagnostics allowing for multi-scale resolution in space and time is addressed.

scholarly journals Microfabrication with Very Low-Average Power of Green Light to Produce PDMS Microchips

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 607
Author(s):  
Lucero M. Hernandez-Cedillo ◽  
Francisco G. Vázquez-Cuevas ◽  
Rafael Quintero-Torres ◽  
Jose L. Aragón ◽  
Miguel Angel Ocampo Mortera ◽  
...  
Keyword(s):  
Low Cost ◽  
Average Power ◽  
Green Light ◽  
Microfluidic Devices ◽  
Processing Parameters ◽  
Coating Film ◽  
Two Dimensional ◽  
Dimethyl Siloxane ◽  
Visible Laser ◽  
High Absorption

In this article, we show an alternative low-cost fabrication method to obtain poly(dimethyl siloxane) (PDMS) microfluidic devices. The proposed method allows the inscription of micron resolution channels on polystyrene (PS) surfaces, used as a mold for the wanted microchip’s production, by applying a high absorption coating film on the PS surface to ablate it with a focused low-power visible laser. The method allows for obtaining micro-resolution channels at powers between 2 and 10 mW and can realize any two-dimensional polymeric devices. The effect of the main processing parameters on the channel’s geometry is presented.

Study on Ultra-Precision Ball Surface Floating Polishing Kinematics Mechanism

2006 ◽  
Vol 532-533 ◽  
pp. 109-112
Author(s):  
Xun Lv ◽  
Ju Long Yuan ◽  
Dong Hui Wen ◽  
Qian Fa Deng ◽  
Fei Yan Lou
Keyword(s):  
Chemical Conversion ◽  
Processing Parameters ◽  
Precision Machining ◽  
High Tech ◽  
National Defense ◽  
Ball Surface ◽  
Angular Velocities ◽  
Ultra Precision ◽  
Relationship Of ◽  
The Mathematical Model

The high precision balls are requested in national defense, astronautics and high-tech commercial domain urgently. Conventional precision machining methods are sensitive to uniformity of abrasives and machining environment. After precision machining, there are easily to produce thick damaged layer on the ball surface because of machining stress and chemical conversion. On the basis of the floating polishing mechanism, a new scatheless ultra-precision polishing method of ball surface can solve the problems of abrasives uniformity effectively and damaged layer. In order to ensure that the new polishing method polishes ball surface equally, the appropriate angular velocities of the ball should be selected. This paper sets up the mathematical model about the motion of ball. By analyzing and simulating the relationship of the angular velocities, the best processing parameters are acquired.

scholarly journals Processing of Protein Crystals using by Deep-UV Pulsed Laser

2014 ◽  
Vol 70 (a1) ◽  
pp. C334-C334
Author(s):  
Yoshiaki Kawano ◽  
Takaaki Hikima ◽  
Kunio Hirata ◽  
Seiki Baba ◽  
Hironori Murakami ◽  
...  
Keyword(s):  
Diffraction Data ◽  
Processing System ◽  
Spherical Shape ◽  
Systematic Errors ◽  
Mirror System ◽  
Protein Crystal ◽  
Protein Crystals ◽  
X Rays ◽  
Uv Laser ◽  
Pass Through

The absorption of X-rays which pass through the protein crystal is possibly the largest source of systematic errors in macromolecular crystallography. Therefore we are developing protein crystal processing system using Pulsed UV Laser Soft Ablation (PULSA) technique [1] to reduce the systematic error as well as background scattering from cryoprotectant agents. For high-quality diffraction data collection from organic material, crystals are usually processed to spherical shape in order to keep X-ray path length in crystal constant. This dramatically reduces systematic errors caused by `absorption of X-rays'. Although shaping crystal was thought to be effective for protein crystallography, there was no usual technique to achieve this because protein crystals are exceedingly fragile against mechanical stress. We are developing protein crystal processing system using PULSA technique. In this system, short pulsed UV-laser (maximum power: 1.0 μJ/pulse, wavelength: 193.4 nm, duration: less than 1.3 nsec) is raised by NSL-193L (Nikon Corporation) and focused on 4 μmφ (FWHM). The focused laser is controlled by galvanomic mirror system and irradiates a sample. Combining this mirror system with four-axis goniometer enables to process crystal to arbitrary shape that is easily defined on GUI. Several protein crystals have been successfully processed into spherical, column and square pole shape, etc. In the case of crystal processed into column shape (diameter is 50 μm), in addition to reducing absorption effects, signal-noise ratio of diffraction data can be increased by removing cryoprotectant agent surrounding the crystal. This work was supported by "Platform for Drug Discovery, Informatics, and Structural Life Science" from MEXT, Japan.

The Research and Application of Vehicle Identification Using KPCA Based on the Car Networking Environment

2011 ◽  
Vol 88-89 ◽  
pp. 709-713
Author(s):  
Wei Xu ◽  
Ru Chuan Wang ◽  
Hai Ping Huang ◽  
Li Juan Sun
Keyword(s):  
Traffic Management ◽  
Processing System ◽  
Principal Component ◽  
Kernel Principal Component Analysis ◽  
Vehicle Classification ◽  
High Tech ◽  
Signal Processing System ◽  
Feature Extraction Method ◽  
Vehicle Identification ◽  
Classification Quality

Traffic systems are increasingly complex, and traffic management works will gradually to become accurate, informationized and intelligent. The traffic management mode based on the experience can no longer adapt to the requirements of development. The introduction of high-tech to control traffic is urgently needed.The proposion of car networking lays a theoretical foundation for this. In this paper, we design, implemented and evaluate a com-pact signal processing system on an embedded mote for vehicle classification via acoustic characteristics. The main components of hardware system include a sound collector, an embedded mote and a wireless transmitting module. In software system we chose kernel principal component analysis (KPCA) as feature extraction method because of its high accuracy of nonlinear differential ability. This system enables an embedded mote to detect a passing vehicle and to decide its type. Using a testbed based on this system, we compare classification quality with the combination of KPCA and SVM to other typical methods. Briefly, we find that the KPCA yields better classification quality than the others in vehicle identification.

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