Ablation Depth

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Yung C Shin - One of the best experts on this subject based on the ideXlab platform.

  • multi scale modeling of phase explosion in high fluence nanosecond laser Ablation and clarification of Ablation Depth prediction criterion
    Applied Surface Science, 2015
    Co-Authors: Yung C Shin
    Abstract:

    Abstract When phase explosion occurs, accurate prediction of the Ablation behavior in the high energy nanosecond laser Ablation process still remains a difficult challenge. In this paper, nanosecond laser Ablation of aluminum and copper with phase explosion is investigated through a multi-scale model and experimental verification. The melt ejection behavior during phase explosion is successfully predicted by combined molecular dynamics (MD) and smoothed particle hydrodynamics (SPH) simulations and validated against the experiments. The commonly adopted 0.9Tc (critical temperature) criterion for phase explosion boundary is also assessed with the prediction of the Ablation Depth for both aluminum and copper, and it is found that the 0.9Tc criterion does not always work. The multi-scale model developed in this work is shown to have better capability in predicting the Ablation behavior when phase explosion is involved.

  • Control of Ablation Depth and Surface Structure in P3 Scribing of Thin-Film Solar Cells by a Picosecond Laser
    Journal of Micro and Nano-Manufacturing, 2014
    Co-Authors: Xin Zhao, Yunfeng Cao, Qiong Nian, Gary J. Cheng, Yung C Shin
    Abstract:

    In this paper, precise P3 scribing of thin-film solar cells (AZO/CIGS/Mo/Glass) via a picosecond laser is investigated. A parametric study is carried out for P3 scribing to study the effects of laser fluence and overlap ratio on Ablation Depth and slot quality, supported by the numerical prediction using a two-temperature model. The optimum scribing conditions are determined, and the potential processing speed is increased. Laser induced periodic surface structures are also presented after the scribing process, which can potentially enhance the absorption of the cell surface and consequently increase the cell efficiency.

  • Control of Ablation Depth and Surface Structure in P3 Scribing of Thin-Film Solar Cells by a Picosecond Laser
    Volume 1: Materials; Micro and Nano Technologies; Properties Applications and Systems; Sustainable Manufacturing, 2014
    Co-Authors: Xin Zhao, Yunfeng Cao, Qiong Nian, Gary J. Cheng, Yung C Shin
    Abstract:

    In this paper, precise P3 scribing of thin-film solar cells (AZO/CIGS/Mo/Glass) via a picosecond laser is investigated. A parametric study is carried out for P3 scribing to study the effects of laser fluence and overlap ratio on Ablation Depth and slot quality, supported by the numerical prediction using a two-temperature model. The optimum scribing conditions are determined, and the potential processing speed is increased. Laser induced periodic surface structures are also presented after the scribing process, which can potentially enhance the absorption of the cell surface and consequently increase the cell efficiency.Copyright © 2014 by ASME

  • Characteristics of plume plasma and its effects on Ablation Depth during ultrashort laser Ablation of copper in air
    Journal of Physics D: Applied Physics, 2012
    Co-Authors: Yung C Shin, Galen B. King
    Abstract:

    The characteristics of plume plasma induced by ultrashort laser Ablation of copper in air are studied experimentally and theoretically in this paper. The plasma front evolutions are captured using a high-speed intensified charge-coupled device camera, while the plasma temperature and electron number density evolutions are obtained from the plasma emission spectra measured by a high-precision spectrometer. For the theoretical study, a hybrid simulation model is proposed to combine an atomistic model for the early stage and a hydrodynamic model for the later stage. The simulation model is validated against the measurement results and shown to be capable of predicting plasma properties for a broader range of fluence, without being constrained by the signal strength as in the measurements. Both experimental and theoretical results show that the nonlinear relationship between plasma properties and laser fluence directly relates to the relationship between Ablation Depth and laser fluence. Therefore, the measurable and predictable plasma properties reveal the underlying Ablation mechanism that has been studied primarily by theory.

Jeff A. Squier - One of the best experts on this subject based on the ideXlab platform.

Farrokh Najmabadi - One of the best experts on this subject based on the ideXlab platform.

  • experimental scaling law for mass Ablation rate from a sn plasma generated by a 1064 nm laser
    Journal of Applied Physics, 2009
    Co-Authors: R Burdt, Sam Yuspeh, K L Sequoia, Mark S. Tillack, Farrokh Najmabadi
    Abstract:

    The Ablation Depth in planar Sn targets irradiated with a pulsed 1064 nm laser was investigated over laser intensities from 3×1011 to 2×1012 W/cm2. The Ablation Depth was measured by irradiating a thin layer of Sn evaporated onto a Si wafer, and looking for signatures of Si ions in the expanding plasma with spectroscopic and particle diagnostics. It was found that Ablation Depth scales with laser intensity to the (5/9)th power, which is consistent with analytical models of steady-state laser Ablation, as well as empirical formulae from previous studies of mass Ablation rate in overlapping parameter space. In addition, the scaling of mass Ablation rate with atomic number of the target as given by empirical formulae in previous studies using targets such as C and Al, are shown to remain valid for the higher atomic number of the target (Z=50) used in these experiments.

  • Ablation Depth in planar Sn targets during the interaction with a Nd:YAG laser for extreme ultraviolet lithography
    Alternative Lithographic Technologies, 2009
    Co-Authors: R Burdt, Sam Yuspeh, K L Sequoia, Mark S. Tillack, Y. Tao, Farrokh Najmabadi
    Abstract:

    The Depth of mass Ablation in planar Sn targets during the interaction with a pulsed Nd:YAG laser was investigated. The pulse duration and laser spot size were fixed, and the laser energy was varied to achieve laser intensities from approximately 10 11 to 10 12 W/cm 2 , which is relevant to the extreme ultraviolet (EUV) lithography application. The Ablation Depth was measured by irradiating layered targets consisting of a thin Sn coating with variable thickness evaporated onto a Si wafer. The Sn coating thickness at which the signatures of Si ions in the expanding plasma disappeared indicated the Ablation Depth. Redundant diagnostics were utilized to detect Si ions in the expanding plasma, including a calibrated EUV energy monitor, an EUV spectrometer, and an electrostatic ion energy analyzer. The Ablation Depth was found to scale with the laser intensity to the (5/9) th power, which is consistent with analytical models of steady-state laser Ablation developed for the laser fusion application, at which laser intensity is generally higher than present in the EUV lithography application.

Ashwini K Sharma - One of the best experts on this subject based on the ideXlab platform.

  • Effect of variation of magnetic field on laser Ablation Depth of copper and aluminum targets in air atmosphere
    Journal of Applied Physics, 2016
    Co-Authors: Khwairakpam Shantakumar Singh, Ashwini K Sharma
    Abstract:

    We report on the effect of transverse magnetic field on laser Ablation of copper and aluminum targets both experimentally and numerically. The Ablation Depth is found to increase with magnetic field from 0 to 0.3 T and decreases at a higher magnetic field (0.5 T). It is demonstrated that the nanosecond laser Ablation is mainly due to melt ejection and it solely depends on the thermo-physical parameters of the material. The increase in Ablation Depth with magnetic field is attributed to the increase in heat transfer from the plasma to the target, vapor pressure, and shock pressure. The Ablation due to melt ejection is also calculated using vapor pressure through simulation and compared with the experimentally measured Depth. In the presence of magnetic field, we introduce the magnetic pressure in Clausius–Clapeyron vapor pressure equation to account for the combined effect of magnetic field and atmospheric pressure on the vapor pressure of plasma. The ratio of calculated Ablation Depth at 0.3 T with respec...

  • Effect of variation of magnetic field on laser Ablation Depth of copper and aluminum targets in air atmosphere
    Journal of Applied Physics, 2016
    Co-Authors: Khwairakpam Shantakumar Singh, Ashwini K Sharma
    Abstract:

    We report on the effect of transverse magnetic field on laser Ablation of copper and aluminum targets both experimentally and numerically. The Ablation Depth is found to increase with magnetic field from 0 to 0.3 T and decreases at a higher magnetic field (0.5 T). It is demonstrated that the nanosecond laser Ablation is mainly due to melt ejection and it solely depends on the thermo-physical parameters of the material. The increase in Ablation Depth with magnetic field is attributed to the increase in heat transfer from the plasma to the target, vapor pressure, and shock pressure. The Ablation due to melt ejection is also calculated using vapor pressure through simulation and compared with the experimentally measured Depth. In the presence of magnetic field, we introduce the magnetic pressure in Clausius–Clapeyron vapor pressure equation to account for the combined effect of magnetic field and atmospheric pressure on the vapor pressure of plasma. The ratio of calculated Ablation Depth at 0.3 T with respect to the absence of magnetic field is close to the corresponding experimental Depth ratios indicating that the laser Ablation modeling in the present work is validated. As the magnetic field increases, we observed the scattered mass at the center and around the crater. The size of deposited mass at the center is found to decrease at higher magnetic field which is attributed to breaking of large droplets into smaller ones due to increase in instability at higher magnetic field.

Alice Z. Chuang - One of the best experts on this subject based on the ideXlab platform.

  • Prediction of corneal haze using an Ablation Depth/corneal thickness ratio after laser epithelial keratomileusis
    Journal of Refractive Surgery, 2004
    Co-Authors: Shrabanee Mitra, Alice Z. Chuang
    Abstract:

    PURPOSE: To investigate the usefulness of Ablation Depth/corneal thickness (AD/CT) ratio to predict corneal haze after laser epithelial keratomileusis (LASEK) using a retrospective, comparative, interventional case series. METHODS: Fifty patients (90 eyes; mean age 40.9 years) with myopia, hyperopia, and/or astigmatism underwent bilateral or unilateral LASEK for correction of refractive error. After epithelial flaps were created using an 18% alcohol solution, bilateral or unilateral LASEK was performed using the Alcon Autonomous LADARVision 4000 excimer laser. usual acuity (best spectacle-corrected and uncorrected) and refractive error were measured before and after LASEK. Corneas were assessed by two independent evaluators under a slit-lamp biomicroscope with broad tangential illumination. The relative haze scale was quantitated: 0 (clear), 0.5+ (trace), 1+ (mild), 2+ (moderate), 3+ (marked), and 4+ (severe). RESULTS: Mean preoperative spherical equivalent refraction was -5.46 ± 3.74 D (range -12.375 to +5.00 D), mean Ablation Depth was 93.04 ± 45.03 μm (range 21.2 to 207.2 μm), and mean AD/CT ratio was 0.18 ± 0.09 (range 0.04 to 0.41). Of 90 eyes, 40 eyes had a higher Ablation Depth (AD/CT ratio >0.18) and 50 eyes had a lower Ablation Depth (AD/CT ratio

  • prediction of corneal haze using an Ablation Depth corneal thickness ratio after laser epithelial keratomileusis
    Journal of Refractive Surgery, 2004
    Co-Authors: Shrabanee Mitra, Alice Z. Chuang
    Abstract:

    PURPOSE: To investigate the usefulness of Ablation Depth/corneal thickness (AD/CT) ratio to predict corneal haze after laser epithelial keratomileusis (LASEK) using a retrospective, comparative, interventional case series. METHODS: Fifty patients (90 eyes; mean age 40.9 years) with myopia, hyperopia, and/or astigmatism underwent bilateral or unilateral LASEK for correction of refractive error. After epithelial flaps were created using an 18% alcohol solution, bilateral or unilateral LASEK was performed using the Alcon Autonomous LADARVision 4000 excimer laser. Visual acuity (best spectacle-corrected and uncorrected) and refractive error were measured before and after LASEK. Corneas were assessed by two independent evaluators under a slit-lamp biomicroscope with broad tangential illumination. The relative haze scale was quantitated: 0 (clear), 0.5+ (trace), 1+ (mild), 2+ (moderate), 3+ (marked), and 4+ (severe). RESULTS: Mean preoperative spherical equivalent refraction was -5.46 +/- 3.74 D (range -12.375 to +5.00 D), mean Ablation Depth was 93.04 +/- 45.03 microm (range 21.2 to 207.2 microm), and mean AD/CT ratio was 0.18 +/- 0.09 (range 0.04 to 0.41). Of 90 eyes, 40 eyes had a higher Ablation Depth (AD/CT ratio > 0.18) and 50 eyes had a lower Ablation Depth (AD/CT ratio < 0.18); 92.5% of eyes in the higher ratio group developed clinically significant haze (1+ or greater). In the lower ratio group, 94% of eyes developed no more than 1+ corneal haze, if any. CONCLUSION: The Ablation Depth/corneal thickness ratio is useful for predicting corneal haze after LASEK. An AD/CT ratio of 0.18 or more suggests that patients have a high risk of developing clinically significant haze (1+ or more) after LASEK.

  • Prediction of corneal haze using an Ablation Depth/corneal thickness ratio after laser epithelial keratomileusis.
    Journal of refractive surgery (Thorofare N.J. : 1995), 2004
    Co-Authors: Ning Lin, Shrabanee Mitra, Alice Z. Chuang, Steven B. Yee, Richard W. Yee
    Abstract:

    PURPOSE To investigate the usefulness of Ablation Depth/corneal thickness (AD/CT) ratio to predict corneal haze after laser epithelial keratomileusis (LASEK) using a retrospective, comparative, interventional case series. METHODS Fifty patients (90 eyes; mean age 40.9 years) with myopia, hyperopia, and/or astigmatism underwent bilateral or unilateral LASEK for correction of refractive error. After epithelial flaps were created using an 18% alcohol solution, bilateral or unilateral LASEK was performed using the Alcon Autonomous LADARVision 4000 excimer laser. Visual acuity (best spectacle-corrected and uncorrected) and refractive error were measured before and after LASEK. Corneas were assessed by two independent evaluators under a slit-lamp biomicroscope with broad tangential illumination. The relative haze scale was quantitated: 0 (clear), 0.5+ (trace), 1+ (mild), 2+ (moderate), 3+ (marked), and 4+ (severe). RESULTS Mean preoperative spherical equivalent refraction was -5.46 +/- 3.74 D (range -12.375 to +5.00 D), mean Ablation Depth was 93.04 +/- 45.03 microm (range 21.2 to 207.2 microm), and mean AD/CT ratio was 0.18 +/- 0.09 (range 0.04 to 0.41). Of 90 eyes, 40 eyes had a higher Ablation Depth (AD/CT ratio > 0.18) and 50 eyes had a lower Ablation Depth (AD/CT ratio < 0.18); 92.5% of eyes in the higher ratio group developed clinically significant haze (1+ or greater). In the lower ratio group, 94% of eyes developed no more than 1+ corneal haze, if any. CONCLUSION The Ablation Depth/corneal thickness ratio is useful for predicting corneal haze after LASEK. An AD/CT ratio of 0.18 or more suggests that patients have a high risk of developing clinically significant haze (1+ or more) after LASEK.

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