scholarly journals Laser-induced ablation of tantalum in a wide range of pulse durations

2020 ◽  
Vol 126 (9) ◽  
Author(s):  
Steffen Mittelmann ◽  
Jannis Oelmann ◽  
Sebastijan Brezinsek ◽  
Ding Wu ◽  
Hongbin Ding ◽  
...  

Abstract We present data and analysis of the laser-induced ablation of pure tantalum (Ta, $$Z=73$$ Z = 73 ). We have identified different physical regimes using a wide range of laser pulse durations. A comparison of the influence of strongly varying laser pulse parameters on high-Z materials is presented. The crater depth caused by three different laser systems of pulse duration $${\varDelta }\tau _1=5\,\mathrm {ns}$$ Δ τ 1 = 5 ns and wavelength $$\lambda _1=1064\,\mathrm {nm}$$ λ 1 = 1064 nm , $${\varDelta }\tau _2=35\,\mathrm {ps}$$ Δ τ 2 = 35 ps , $$\lambda _2=355\,\mathrm {nm}$$ λ 2 = 355 nm and $${\varDelta }\tau _3=8.5\,\mathrm {fs}$$ Δ τ 3 = 8.5 fs , $$\lambda _3=790\,\mathrm {nm}$$ λ 3 = 790 nm are analyzed via confocal microscopy as a function of laser fluence and intensity. The minimum laser fluence needed for ablation, called threshold fluence, decreases with shorter pulse duration from $$1.10\,\mathrm {J/cm}^2$$ 1.10 J / cm 2 for the nanosecond laser to $$0.17\,\mathrm {J/cm}^2$$ 0.17 J / cm 2 for the femtosecond laser.

Author(s):  
Xiaoxu Liu ◽  
Kohei Natsume ◽  
Satoru Maegawa ◽  
Fumihiro Itoigawa

Abstract To realize the high performance of CVD diamond coated tools, a tool edge shaping process named pulse laser grinding (PLG) was developed with short pulse laser in our group previously. In this study, femtosecond laser was innovatively to be used to conduct the PLG process, since femtosecond laser is famous for its less thermal impact and some newly reported surface modification effect. The results show that PLG processing under high laser fluence of femtosecond laser could achieve roundness around 1 μm, which is similar to that of conventional PLG process with nanosecond laser, although the roughness of processed surface has been worse due to the redeposited debris. Furthermore, an interesting phenomenon has been confirmed again that under low laser fluence irradiation of femtosecond laser, the CVD diamond surface shows improved crystallinity of diamond structure. Based on this, a two-step tool edge processing method was proposed, which could realize the edge shaping and surface modification together with one laser processor. And the results show that the processed tool edge with much less edge roundness and surface roughness, and the tip part with better diamond crystallinity, indicating that sharper and hardness tool edge could be possibly to be realized with femtosecond laser.


Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 969 ◽  
Author(s):  
Georg Schnell ◽  
Ulrike Duenow ◽  
Hermann Seitz

Surface structuring is a key factor for the tailoring of proper cell attachment and the improvement of the bone-implant interface anchorage. Femtosecond laser machining is especially suited to the structuring of implants due to the possibility of creating surfaces with a wide variety of nano- and microstructures. To achieve a desired surface topography, different laser structuring parameters can be adjusted. The scanning strategy, or rather the laser pulse overlap and scanning line overlap, affect the surface topography in an essential way, which is demonstrated in this study. Ti6Al4V samples were structured using a 300 fs laser source with a wavelength of 1030 nm. Laser pulse overlap and scanning line overlap were varied between 40% and 90% over a wide range of fluences (F from 0.49 to 12.28 J/cm²), respectively. Four different main types of surface structures were obtained depending on the applied laser parameters: femtosecond laser-induced periodic surface structures (FLIPSS), micrometric ripples (MR), micro-craters, and pillared microstructures. It could also be demonstrated that the exceedance of the strong ablation threshold of Ti6Al4V strongly depends on the scanning strategy. The formation of microstructures can be achieved at lower levels of laser pulse overlap compared to the corresponding value of scanning line overlap due to higher heat accumulation in the irradiated area during laser machining.


2014 ◽  
Vol 2 ◽  
Author(s):  
Qingwei Yang ◽  
Xinglong Xie ◽  
Jun Kang ◽  
Haidong Zhu ◽  
Ailin Guo ◽  
...  

Abstract The dispersion of a pair of prisms is analyzed by means of a ray-tracing method operating at other than tip-to-tip propagation of the prisms, taking into consideration the limited spectral bandwidth. The variations of the group delay dispersion and the third-order dispersion for a pair of prisms are calculated with respect to the incident position and the separation between the prisms. The pair of prisms can provide a wide range of independent and continuous third-order dispersion compensation. The effect of residual third-order dispersion on the pulse contrast ratio and pulse duration is also calculated. The residual third-order dispersion not only worsens the pulse contrast ratio, but also increases the pulse duration to the hundreds of femtosecond range for a tens of femtosecond pulse, even when the residual third-order dispersion is small. These phenomena are helpful in compensating for the residual high-order dispersion and in understanding its effect on pulse contrast ratios and pulse durations in ultrashort laser systems.


Author(s):  
Fangjian Zhang ◽  
Shuchang Li ◽  
Anmin Chen ◽  
Yuanfei Jiang ◽  
Suyu Li ◽  
...  

The ultrafast dynamic process in semiconductor Ge irradiated by the femtosecond laser pulses is numerically simulated on the basis of van Driel system. It is found that with the increase of depth, the carrier density and lattice temperature decrease, while the carrier temperature first increases and then drops. The laser fluence has a great influence on the ultrafast dynamical process in Ge. As the laser fluence remains a constant value, though the overall evolution of the carrier density and lattice temperature is almost independent of pulse duration and laser intensity, increasing the laser intensity will be more effective than increasing the pulse duration in the generation of carriers. Irradiating the Ge sample by the femtosecond double pulses, the ultrafast dynamical process of semiconductor can be affected by the temporal interval between the double pulses.


Author(s):  
G. Pozza ◽  
S. Kroesen ◽  
G. Bettella ◽  
A. Zaltron ◽  
M. Esseling ◽  
...  

AbstractA femtosecond laser at 800 nm was used to create micro-fluidic circuits on lithium niobate (LiNbO3) substrates by means of laser ablation, using different scanning velocities (100-500 μm/s) and laser pulse energies (1-20 μJ). The T-junction geometry was exploited to create on y-cut LiNbO3 crystals a droplet generator, whose microfluidic performance was characterized in a wide range of droplet generation frequencies, from few Hz to about 1 kHz.


2010 ◽  
Vol 53 (6) ◽  
pp. 849-852
Author(s):  
G. M. Mikheev ◽  
V. V. Vanyukov ◽  
T. N. Mogileva ◽  
A. V. Okotrub

2000 ◽  
Author(s):  
Mengqi Ye ◽  
Costas P. Grigoropoulos

Abstract Femtosecond laser ablation of titanium and silicon samples has been studied via time-of-flight (TOF), emission spectroscopy and microscopy measurement. Laser pulses of around 100 fs (FWHM) at λ = 800 nm were delivered by a Ti:sapphire femtosecond laser system. A vacuum chamber with a base pressure of 10−7 torr was built for ion TOF measurement. These ion TOF spectra were utilized to determine the velocity distribution of the ejected ions. While nanosecond laser ablation typically generates ions of a few tens of eV, femtosecond laser irradiation even at moderate energy densities can produce energetic ions with energies of up to a few keV. The most probable energy of these fast ions is proportional to the laser fluence. The structure and number of peaks of the TOF spectra varies with the laser fluence. Images of plume emission were captured by an intensified CCD (ICCD) camera. The plume emission spectrum was analyzed by a spectrometer. Laser ablated craters were measured by an interferometric microscope and a scanning electron microscope (SEM). Ablation yield was expressed as a function of laser fluence, and number of shots.


Sign in / Sign up

Export Citation Format

Share Document