Beam-Metal Surface Interactions Using an Excimer Laser

1986 ◽  
Vol 82 ◽  
Author(s):  
Joseph Pellegrino ◽  
Julian P. Partridge ◽  
A. Magee ◽  
P. Strutt
Keyword(s):  
Excimer Laser ◽  
Single Pulse ◽  
Surface Interactions ◽  
Lens System ◽  
Incident Intensity ◽  
Beam Focusing ◽  
Beam Incidence ◽  
Technological Developments ◽  
Ripple Patterns ◽  
Power Densities

ABSTRACTIn view of material technological developments, studies have been made of the interactive processes involved in irradiation of metals with an excimer laser. These studies involved single-pulse irradiation of Al, Ni, Ti, and Zn at various powers up to about 5 MW. Systematic studies at widely differing, yet reproducible, power densities were facilitated using numerically controlled beam focusing. By changing the incident intensity, different plasma pressures were produced during surface melting. These created various types of unstable ripple patterns which emanated radially from the center of beam incidence and were enhanced by immersion in liquid nitrogen.The results showed only minor differences between substrates possessing different physical properties and the influence of crystallographic orientation was also found to be minimal. An elliptical disturbance zone was produced on the substrates when the beam was defocused and this is attributed to astigmatic effects associated with a lens system incorporating spherical refracting surfaces.

Single pulse vibrational Raman scattering by a broadband KrF excimer laser in a hydrogen–air flame

1990 ◽  
Vol 29 (15) ◽  
pp. 2325 ◽  
Author(s):  
Robert W. Pitz ◽  
Joseph A. Wehrmeyer ◽  
J. M. Bowling ◽  
Tsarng-Sheng Cheng
Keyword(s):  
Raman Scattering ◽  
Excimer Laser ◽  
Single Pulse ◽  
Krf Excimer Laser

Femtosecond Pulsed Laser-Induced Micromachining of Difficult-to-Machine Materials: Diamond a Case Study

2000 ◽  
Author(s):  
A. P. Malshe ◽  
A. M. Ozkan ◽  
T. A. Railkar ◽  
K. P. Adhi ◽  
W. D. Brown ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Excimer Laser ◽  
Etching Rate ◽  
Polycrystalline Diamond ◽  
Single Pulse ◽  
Laser Wavelength ◽  
Diamond Surface ◽  
Single Shot ◽  
Micro Machining ◽  
3 Dimensional

Abstract Meso and micro scale machining is an important and emerging area of research. Various non-traditional and novel tools are being explored for meso and micro machining of non-silicon materials. In this paper, we report etching, micro machining and related phenomena of commercially available single and polycrystalline diamond using a femtosecond pulsed excimer laser (λ = 248 nm, tp ∼ 380 fs). Surface modifications due to single pulse and multiple pulse irradiation of diamond samples, at different energy densities, have been analyzed using Raman spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Etching rate of single crystal type IIA diamond by femtosecond pulsed excimer laser is also studied. Raman spectroscopy study of the single shot irradiation of diamond with a femto second laser shows the formation of a non-diamond disordered (sp2 bonded) phase on the surface. However, subsequent micro machining of this non-diamond disordered surface, by delivering several shots from the femtosecond laser, results in the removal of the non-diamond disordered layer and the restoration of the diamond surface. It is experimentally shown that the periodicity of the 2-dimensional corrugations written on diamond surface is shorter than the laser wavelength used. 3-dimensional writing on diamond globules during laser etching is also discussed. Further, micro machining of diamond tips is shown to be precise, and without mechanical and chemical damages. Femto second laser is demonstrated as a next-generation tool for mechanical and chemical damage free precision micro machining of the hardest material, diamond.

Multiple Pulse Irradiation Effects in Excimer Laser-Induced Crystallization of Amorphous Si Films

1993 ◽  
Vol 321 ◽  
Author(s):  
H. J. Kim ◽  
James S. Im
Keyword(s):  
Excimer Laser ◽  
Single Pulse ◽  
Pulse Irradiation ◽  
Multiple Pulse ◽  
Melting Phenomenon ◽  
Irradiation Energy ◽  
Crystallization Experiments ◽  
Amorphous Si ◽  
Si Films ◽  
Induced Crystallization

ABSTRACTWe have experimentally Investigated the effects that are associated with Multiple-pulse irradiation in the excimer laser processing of thin Si films on SiO2. Double-pulse irradiation experiments revealed results, which are consistent with that which is known from single-pulse crystallization experiments, and these experiments confirm the applicability of the transformation scenarios, which were derived from single pulse-induced crystallization experiments [1,2]. The results from the Multiple-pulse irradiation experiments clearly show that gradual and substantial grain enlargement can occur — and only occurs — when the irradiation energy density is close to but less than the level that is required to melt the film completely. Based on these findings, we argue that the grain enlargement effect is a near-complete melting phenomenon that is associated with polycrystalline Si films, and we present a grain boundary melting model to account for this phenomenon. A brief discussion on the apparent similarities and physical differences between the observed phenomenon and the solid state grain growth processes is provided herein.

Oxide Phase Formation in Excimer Laser Processed Ti Alloy

1991 ◽  
Vol 236 ◽  
Author(s):  
T. R. Jervis ◽  
K. M. Hubbard ◽  
T. G. Zocco
Keyword(s):  
Surface Layer ◽  
Excimer Laser ◽  
Single Pulse ◽  
Oxide Phase ◽  
Grain Structure ◽  
Ti Alloy ◽  
Fine Grained ◽  
Pulse Processing ◽  
Oxygen Incorporation ◽  
Oxide Phases

AbstractExcimer laser surface processing of Ti-6A1-4V results in substantial surface oxygen incorporation as measured by the narrow resonance in the elastic scattering of a particles at 3.05 MeV. Single pulse processing at 1.0 J-cm−2 results in transformation from the original a + β grain structure to a martensite structure. Multiple pulse processing results in oxygen incorporation proportional to the number of pulses during processing, but this is primarily reflected in the depth of the oxygen containing layer. A maximum oxygen to titanium ratio of 1.0 was observed in the surface layer. This was confirmed by transmission electron microscopy (TEM) which showed the development of a fine-grained equiaxed TiO surface layer from a phase mixture of Ti alloy with TiO precipitates. Concentration vs. depth profiles show that this layer is approximately 400 nm thick after 40 pulses. Further processing with a total of 60 pulses results in coarsening of the grains and an increase in the thickness of the layer. The TiO precipitate concentration increases gradually, becoming apparent in electron diffraction patterns after 30 pulses. No other oxide phases are observed, the TiO developing directly from the metallic phases. In particular, we do not observe the formation of Ti2O prior to the formation of the TiO, or the formation of TiO2.

Single-pulse excimer laser nanostructuring of silicon: A heat transfer problem and surface morphology

2008 ◽  
Vol 103 (9) ◽  
pp. 094311 ◽  
Author(s):  
Julia Eizenkop ◽  
Ivan Avrutsky ◽  
Daniel G. Georgiev ◽  
Vipin Chaudchary
Keyword(s):  
Heat Transfer ◽  
Surface Morphology ◽  
Excimer Laser ◽  
Transfer Problem ◽  
Single Pulse ◽  
Heat Transfer Problem ◽  
Pulse Excimer Laser

The Development of Excimer Laser Technology – History and Future Prospects

2001 ◽  
Vol 215 (12) ◽  
Author(s):  
D. Basting ◽  
U. Stamm
Keyword(s):  
Excimer Laser ◽  
Fused Silica ◽  
Pulsed Power ◽  
Excimer Lasers ◽  
Laser Technology ◽  
Research Areas ◽  
Technological Developments ◽  
Laser Development ◽  
Application Requirements ◽  
User Friendly

With focus on commercial aspects the paper reviews the historical development and various technological achievements in the field of excimer lasers since their discovery in 1970. The first commercial excimer laser model in the world, the EMG 500 from Lambda Physik was operating at maximum repetition rates of only 20 Hz, whereas today multi kHz excimer lasers as the NovaLine industrial lasers are available. In 2000, Lambda Physik introduced the most powerful commercial excimer laser, the Lambda Steel with 300 W output power having extremely high stability.In the more than 30 years of excimer lasers their properties have been studied in a multitude of research laboratories at universities, institutes, national laboratories, and industry. In the attempts to reach parameters in the UV never seen before, energies ranging from mJ to kJ, pulse durations from sub μs down to fs, spectral bandwidths from fractions of 1 nm down to less then 0.1 pm, and beam divergence from 10 mrad down to 10 μrad could be demonstrated at the various excimer lasers wavelengts. Over the years various technological achievements like the NovaTube laser chamber technology, the NovaPowerSwitch pulsed power modules and the HaloSafe fluorine and chlorine generators could be made which make the use of excimer lasers simple and user friendly. Recently, the development of DuraTube technology gave a strong push towards the development of high power 157 nm laser technology for microlithography and laser based micro-machining of “difficult” materials as fused silica or teflon.The paper describes important steps and quantum leaps in developing and improving excimer lasers. Since a large part of excimer laser development was driven by application requirements some applications developed over the years are touched as well – including early photochemistry and dye laser pumping in F. P. Schäfers laboratories. Finally, currently ongoing and for the future expected technological developments are discussed which will strengthen the position of excimer lasers as user friendly work horses in many industrial and research areas.

CRACKING AND EXFOLIATION OF TiO2 FILM IRRADIATED WITH EXCIMER LASER

2008 ◽  
Vol 15 (04) ◽  
pp. 473-479 ◽  
Author(s):  
H. X. QIAN ◽  
W. ZHOU ◽  
H. Y. ZHENG
Keyword(s):  
Excimer Laser ◽  
Laser Fluence ◽  
Single Pulse ◽  
Single Shot ◽  
Uv Laser ◽  
Original Surface ◽  
Excimer Laser Pulse ◽  
Surface Protrusion ◽  
Krf Excimer Laser ◽  
Effect Of Surface

TiO 2 film deposited on glass was irradiated in air with single-shot KrF excimer laser pulse. The surface roughened as the result of the laser ablation. It is further noted that single-pulse irradiation with fluence ranging from 400 to 1200 mJ/cm2 gave rise to protrusion of the irradiated surface above the original surface, which is in contrast to usual expectation that irradiated surface is below the unirradiated surface. The surface protrusion is mainly attributed to the effect of surface tension. At the laser fluence of 1000 mJ/cm2, cracks were formed in the irradiated area and severe film exfoliation was observed at the periphery of the irradiated area due to the release of internal stress. With higher laser fluence above 1000 mJ/cm2, patches of film were observed to peel off within the irradiated areas. Hydrodynamic ablation is proposed to account for film exfoliation. The observed phenomenon is useful for further understanding how TiO 2 film reacts to strong UV laser irradiation.

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