Computer modeling of coupled electrodynamical and thermal processes of laser-radiation interaction with matter for two-dimensional geometry

Laser ablation using ultrafast femtosecond lasers and holographic schemes has proven to be a powerful and versatile tool for surface and volume structuring. The principle of operation of this technique is simple: when two or more pulses overlap in time and space, an interference pattern is generated that can be used to create periodic surface structures. In addition, due to the extremely short pulse duration, a very high peak power is achieved leading to intense non-linear effects. As a result, almost any type of material can be processed without undesirable collateral thermal effects.In this paper, characterization of two-dimensional (2D) patterns generated in titanium using femtosecond laser radiation has been carried out using scanning electron microscopy (SEM). The laser source is a commercial Yb:KYW laser system providing pulses with a duration of 560 fs at a central wavelength of >= 1030 nm. The surface topography was characterized using a Hitachi S2400 scanning electron microscope operated at an electron acceleration voltage of 25.0 kV. Laser processing was performed in air on polished grade 2 titanium samples, a material typically used in low load bearing medical devices.One-dimensional (1D) gratings were created using a modified Michelson interferometer described in detail elsewhere (Oliveira et al., 2012). To create 2D gratings a double exposure method was used. First, 1D gratings were produced in linear tracks by translating the sample relatively to the stationary interfering laser beams with a fixed scanning velocity of 0.1 mm/s. As an example, Figure 1 depicts SEM pictures of horizontal and vertical 1D gratings with period of about 3.9 m, generated using a pulse energy and pulse repetition rate of 0.35 mJ and 100 Hz, respectively. The peak to valley distance of these patterns can be controlled either by changing the scanning velocity or the pulse repetition rate. By overlapping two linear tracks, different kinds of 2D structures can be created. Figure 2 depicts a square pattern obtained by overlapping two 1D gratings rotated by 90°. The dimensions of the squares depend on the one-dimensional gratings period, which in turn can be easily controlled by varying the distance between the interfering beams. Figure 3 depicts two other possibilities: i) trapezium-like patterns obtained by rotating the 1D gratings by 45°, and ii) rectangular patterns obtained using 1D gratings with different periods and rotated by 90°.The proposed optical setup offers a simple method of texturing the surface of materials and, hence, to control surface properties such as wettability. In the case of titanium, this is particularly important because surface texturing enhances its osseointegration ability. For this purpose, when compared with the columns spontaneously formed on titanium surfaces treated with femtosecond laser radiation, these 2D gratings present the major advantage of being size and shape-controllable.

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CALCULATION OF DIFFRACTION OF LASER RADIATION BY A TWO-DIMENSIONAL (CYLINDRICAL) AXICON WITH THE HIGH NUMERICAL APERTURE IN VARIOUS MODELS

Computer Optics ◽

10.18287/0134-2452-2014-38-4-670-680 ◽

2014 ◽

Vol 38 (4) ◽

pp. 670-680 ◽

Cited By ~ 2

Author(s):

S. N. Khonina ◽

A. V. Ustinov ◽

S. A. Degtyarev

Keyword(s):

Laser Radiation ◽

Numerical Aperture ◽

Two Dimensional ◽

High Numerical Aperture

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THE COMPUTER MODELING AND RESULTS VISUALISATION ALGORITHM OF VISCOUS INCOMPRESSIBLE LIQUID FLOWING IN THE TWO-DIMENSIONAL DEFINITION AREA

Vestnik komp iuternykh i informatsionnykh tekhnologii ◽

10.14489/vkit.2017.11.pp.016-022 ◽

2017 ◽

pp. 16-22

Author(s):

L. G. Varepo ◽

K. L. Panchuk ◽

A. V. Panichkin

Keyword(s):

Computer Modeling ◽

Incompressible Liquid ◽

Viscous Incompressible Liquid ◽

Two Dimensional

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Simultaneous Two-Dimensional Visualization of Soot and OH in Flames Using Laser-Induced Fluorescence

Applied Spectroscopy ◽

10.1366/0003702963905132 ◽

1996 ◽

Vol 50 (9) ◽

pp. 1182-1186 ◽

Cited By ~ 11

Author(s):

Per-Erik Bengtsson

Keyword(s):

Laser Radiation ◽

Detection System ◽

Frequency Doubling ◽

Ccd Camera ◽

Laser Induced Fluorescence ◽

Oh Radicals ◽

Single Shot ◽

Two Dimensional ◽

Charge Coupled Device ◽

Reaction Zones

Two-dimensional visualization of soot has been realized in flames with the use of laser-induced fluorescence in C2 from laser-vaporized soot [LIF(C2)LVS]. Soot particles are heated to vaporization temperatures by the absorption of laser radiation. C2 radicals produced by this process are excited at wavelengths around 563 nm through the transition v’ = 0 d3Πg ← v” = 1 a3Πu, and the subsequent fluorescence at ∼516 nm is detected. By frequency-doubling of the laser radiation, wavelengths around 281.5 nm are achieved, which can excite OH radicals to the v’ = 1 A2∑+ state from v” = 0 X2Π, with subsequent fluorescence at ∼310 nm. With the use of both these excitation wavelengths, and a Cassegrainian split-mirror telescope as the imaging detection system in front of the charge-coupled device (CCD) camera, simultaneous two-dimensional single-shot images of soot and OH were obtained on a single CCD chip, thus enabling both sooting regions and reaction zones in flames to be monitored.

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