scholarly journals Single-pulse ablation of multi-depth structures via spatially filtered binary intensity masks

2018 ◽  
Vol 57 (8) ◽  
pp. 1904 ◽  
Author(s):  
Daniel J. Heath ◽  
James A. Grant-Jacob ◽  
Robert W. Eason ◽  
Ben Mills
Keyword(s):  
Single Pulse ◽  
Single Pulse Ablation

Residual heat during laser ablation of metals with bursts of ultra-short pulses

2018 ◽  
Vol 7 (3) ◽  
pp. 175-182 ◽  
Author(s):  
Beat Jäggi ◽  
Daniel J. Förster ◽  
Rudolf Weber ◽  
Beat Neuenschwander
Keyword(s):  
Removal Rate ◽  
Single Pulse ◽  
Residual Energy ◽  
Short Pulses ◽  
Pulse Burst ◽  
Calorimetric Measurements ◽  
Key Factor ◽  
Energy Coefficient ◽  
Single Pulse Ablation ◽  
Residual Heat

Abstract The usage of pulse bursts allows increasing the throughput, which still represents a key factor for machining with ultra-short pulsed lasers. The influence of the number of pulses within a burst on the specific removal rate is investigated for copper and stainless steel. Furthermore, calorimetric measurements were performed to estimate the residual energy coefficient as well as the absorptance of machined surfaces for copper to explain the reduced specific removal rate for a 2-pulse burst and the similar or even higher rate for a 3-pulse burst compared to single pulse ablation. Based on the measurements, a description of the process using single pulses and pulse bursts with up to three pulses is presented.

Investigation of Femtosecond Laser Ablation Threshold for Nickel Template

2014 ◽  
Vol 633-634 ◽  
pp. 665-670 ◽  
Author(s):  
Lei Zhang ◽  
Xiao Wen Cao ◽  
Shun Guang Li ◽  
Ru Yi Xiang ◽  
Hui Chao Sun
Keyword(s):  
Femtosecond Laser ◽  
Ablation Threshold ◽  
Femtosecond Laser Ablation ◽  
Target Surface ◽  
Single Pulse ◽  
Normal Incidence ◽  
Objective Lens ◽  
Temperature Model ◽  
Two Temperature ◽  
Single Pulse Ablation

This paper presents a theoretical and experimental investigation into the ablation threshold of nickel template by femtosecond laser in air at atmospheric pressure. The laser pulses used for the study are 800 nm in wavelength, 100fs in pulse duration, and 1KHz in repetition rate. The two-temperature model is used to predict the single-pulse ablation threshold for nickel theoretically. Micro-hole ablation experiments are carried out in air by focusing the femtosecond laser beam on the nickel target surface at normal incidence with the long-focus objective lens of enlargement factor 50 and NA=0.7 to determine the single-pulse and multi-pulse ablation thresholds for nickel by setting up the relationship between the measured hole diameters and the pulse energies. The single pulse ablation threshold of 4132.98 Jm-2obtained experimentally is very close to that of 3907.99 Jm-2predicted by two-temperature model. The incubation factorξ, which describes the changes of the multi-pulse ablation thresholds with the number of pulses, is determined to be 0.812 for nickel.

Pyrolysis of methane in a single pulse shock tube

1972 ◽  
Vol 22 (3) ◽  
pp. 303-317 ◽  
Author(s):  
D. H. Napier ◽  
N. Subrahmanyam
Keyword(s):  
Shock Tube ◽  
Single Pulse

Efficiency Improvement of Switched Reluctance Motor by Single-Pulse Control with Variable Excitation Period

2015 ◽  
Vol 135 (3) ◽  
pp. 284-290 ◽  
Author(s):  
Yoshihiro Nakazawa ◽  
Kazuhiro Ohyama ◽  
Hiroaki Fujii ◽  
Hitoshi Uehara ◽  
Yasushi Hyakutake
Keyword(s):  
Single Pulse ◽  
Switched Reluctance Motor ◽  
Efficiency Improvement ◽  
Pulse Control ◽  
Switched Reluctance ◽  
Reluctance Motor ◽  
Excitation Period

Action processing in the motor system: TMS evidence of shared mechanisms in the visual and linguistic modalities.

2018 ◽  
Author(s):  
Claudia Gianelli ◽  
Katharina Kühne ◽  
Silvia Mencaraglia ◽  
Riccardo Dalla Volta
Keyword(s):  
Motor System ◽  
Native Speakers ◽  
Motor Evoked Potentials ◽  
Single Pulse ◽  
Stimulus Presentation ◽  
Corticospinal Excitability ◽  
First Dorsal Interosseous ◽  
Action Processing ◽  
Abductor Digiti Minimi ◽  
Hand Action

In two experiments, we compared the dynamics of corticospinal excitability when processing visually or linguistically presented tool-oriented hand actions in native speakers and sequential bilinguals. In a third experiment we used the same procedure to test non-motor, low-level stimuli, i.e. scrambled images and pseudo-words. Stimuli were presented in sequence: pictures (tool + tool-oriented hand action or their scrambled counterpart) and words (tool noun + tool-action verb or pseudo-words). Experiment 1 presented German linguistic stimuli to native speakers, while Experiment 2 presented English stimuli to non-natives. Experiment 3 tested Italian native speakers. Single-pulse trascranial brain stimulation (spTMS) was applied to the left motor cortex at five different timings: baseline, 200ms after tool/noun onset, 150, 350 and 500ms after hand/verb onset with motor-evoked potentials (MEPs) recorded from the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles.We report strong similarities in the dynamics of corticospinal excitability across the visual and linguistic modalities. MEPs’ suppression started as early as 150ms and lasted for the duration of stimulus presentation (500ms). Moreover, we show that this modulation is absent for stimuli with no motor content. Overall, our study supports the notion of a core, overarching system of action semantics shared by different modalities.

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