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Late complications of radial keratotomy (RK), are as a rule caused by a change in the biomechanical properties of the cornea.Purpose: to study the long-term stabilizing effect of the Bowman’s layer (BL) transplantation after RK.Material and methods. In a limited, prospective, monocentric pilot study we operated 2 male patients (2 eyes) aged 60 and 55. The radial incisions had been performed 34 and 38 years ago. The indications for surgery were progressive biomechanical instability of the cornea and functional refractive visual fluctuations. Within 12 months after the operation, complications, corrected visual acuity, keratometric parameters, biomicroscopic transparency of the cornea, and patient satisfaction were assessed.Results. No complications were noted during the follow-up period, the cornea and graft retained transparency. The average thickness of the BS graft was 20±2.1 µm. The average visual acuity corrected by contact lenses increased from 0.4±0.3 to 0.65±0.1, the average indicator of keratometric astigmatism changed from 1.9±1.6 to 3.0 D, these indicators remained after 6, 9 and 12 months, which indicates that biomechanical stability of the cornea was achieved and that the refractive-visual fluctuations are absent.Conclusion. In late term RK complications, BS transplantation partially restores the normal anatomy of the anterior surface of the cornea and ensures its biomechanical stability during a 12-month follow-up period. For the conclusions to be maximally objective, more clinical cases should be studied within a longer observation period.

Purpose: To evaluate the safety and effectiveness of excimer laser ablation (ELA) combined with drug-coated balloon (DCB) for atherosclerotic obliterans (ASO) of the lower extremities. Materials and Methods: From June 2019 to December 2020, all eligible patients were enrolled. Demographics, characteristics of lesions, complications, and follow-up information were collected and analyzed. The primary endpoint was major amputation-free survival (MAFS). Secondary endpoints included technical success, primary patency, bailout stent, distal embolization, target lesion reintervention (TLR), and ulcer healing rate. Major amputation-free survival and primary patency were calculated by Kaplan-Meier analysis. Results: A total of 71 patients were enrolled. Forty-eight (81.7%) patients presented critical limb ischemia (CLI) and 48.6% of them was calcification class 4 according to Peripheral Arterial Calcium Scoring System (PACSS). Chronic totally occluded (CTO) disease was the most common lesion in 66.0% of them and superficial femoral artery (SFA) was the most common segment in 59.6%. Technical success rate was 93.0%. One-year follow-up was finished in 25 (35.2%) patients. The primary patency and MAFS were 92.0%±27.6% and 96.0%±20.0% at 12 months, respectively. During the mean follow-up of 9.4±4.3 months, clinically-driven TLR occurred in 2 (2.8%) patients, and major and minor amputation occurred in 2 (2.8%) and 1 (1.4%) patient, respectively. Conclusion: The early results demonstrated that ELA was an effective treatment in de novo, in-stent restenosis (ISR) and CTO lesions. Meanwhile, ELA could prepare the lumen for the use of DCB and reduce the implantation of stents, especially in segments unsuitable for stenting. Mid-term and long-term results need to be awaited. [ABSTRACT FROM AUTHOR]

Abstract Background The efficacy and validity of excimer laser ablation (ELA) in the in-stent restenosis (ISR) has been confirmed. However, its application in de novo atherosclerotic lesions of lower extremity artery disease (LEAD) has not been clearly defined and its procedure has not been standardized. Methods ELABORATE is a prospective, multicenter, real-world study designed to evaluate the efficacy and safety between ELA combined with drug-coated balloon (DCB) and DCB alone in de novo atherosclerotic lesions of LEAD. Discussion ELABORATE is a prospective, multicenter, real-world study designed to assess the efficacy and safety between ELA combined with drug-coated balloon (DCB) and DCB alone in patients with de novo atherosclerotic lesions of LEAD. According to the real-world situation, eligible patients will be allocated to ELA + DCB group (group E) and DCB group (group C). Baseline and follow-up information (at 3, 6, and 12 months) will be collected. The primary efficacy point is primary patency at 12-months, and the secondary efficacy points include clinically driven target lesion reintervention (CD-TLR), change of Rutherford class, ankle-brachial index and ulcer healing rate. These indexes will be assessed and recorded at 3, 6, and 12-month follow-up. Also, safety evaluation, including major adverse event, all-cause mortality through 30-day follow-up, unplanned major amputation, bailout stent and distal embolization, will also be evaluated by an independent core laboratory. All the data will be collected and recorded by the electric data capture system. This study will be finished in 3 years and the 12-month results will be available in 2023. All the patients will be followed for 5 years. Trial registration number Chinese Clinical Trial Registry (ChiCTR2100051263). Registered 17 September 2019. http://www.chictr.org.cn/listbycreater.aspx .

Seasonal changes and varying degree of corneal hydration has been linked to excimer laser corneal ablation rates. The use of PMMA as a calibration material in refractive lasers is well established. However, PMMA ablation may be equally affected by seasonal variations in temperature and humidity, in turn affecting the calibration process. The aim of this work is to analyze the effect of seasonal changes in PMMA performance using SCHWIND AMARIS laser system. PET and PMMA ablations conducted in climate-controlled environment with 826 consecutive AMARIS systems manufactured over 6 years were retrospectively analyzed. Lasers were stratified depending on seasons and months of the year. Metrics like single laser pulse fluence, nominal number of laser pulses, mean performance, standard deviation, and technical performance of system were compared to global average values. Cyclic winter–summer variation was confirmed with seasons winter and summer showing statistically significant variations with respect to global values. Metric technical performance showed deeper PMMA ablation performance in summertime, with maximum seasonal deviation of 6%. Results were consistently confirmed in seasonal as well as monthly analyses. These findings could help minimize variance among laser systems by implementing compensation factors depending on seasons such that laser systems installed worldwide follow the same trend line of variation.

Background: The efficacy and validity of excimer laser ablation (ELA) in the in-stent restenosis (ISR) has been confirmed. However, its application in de novo atherosclerotic lesions of lower extremity artery disease (LEAD) has not been clearly defined and its procedure has not been standardized.Methods: ELABORATE is a prospective, multicenter, real-world study designed to evaluate the efficacy and safety between ELA combined with drug-coated balloon (DCB) and DCB alone in de novo atherosclerotic lesions of LEAD.Discussion: ELABORATE is a prospective, multicenter, real-world study designed to assess the efficacy and safety between ELA combined with drug-coated balloon (DCB) and DCB alone in patients with de novo atherosclerotic lesions of LEAD. According to the real-world situation, eligible patients will be allocated to ELA + DCB group (group E) and DCB group (group C). Baseline and follow-up information (at 3, 6, and 12 months) will be collected. The primary efficacy point is primary patency at 12-months, and the secondary efficacy points include clinically driven target lesion reintervention (CD-TLR), change of Rutherford class, ankle-brachial index and ulcer healing rate. These indexes will be assessed and recorded at 3, 6, and 12-month follow-up. Also, safety evaluation, including major adverse event, all-cause mortality through 30-day follow-up, unplanned major amputation, bailout stent and distal embolization, will also be evaluated by an independent core laboratory. All the data will be collected and recorded by the electric data capture system. This study will be finished in 3 years and the 12-month results will be available in 2023. All the patients will be followed for 5 years. Trial registration number Chinese Clinical Trial Registry (ChiCTR2100051263). Registered 17 September 2019. http://www.chictr.org.cn/listbycreater.aspx . [ABSTRACT FROM AUTHOR]

Purpose. To evaluate safety and efficacy of customized central corneal regularization (CCR), together with simultaneous accelerated corneal collagen cross-linking (A-CXL) - CCR-CXL protocol, to treat keratoconus-related corneal ectasia. Design. Retrospective, comparative observational case series. Methods. Patients that had undergone combined CCR-CXL protocol. Main inclusion criteria were keratoconus visual acuity deterioration and contact lens intolerance. All patients underwent complete ophthalmological evaluation, corrected distance visual acuity (CDVA) and Scheimpflug-corneal tomography. Central corneal regularization was performed by ablation using flying spot laser. Subsequently, the stroma was saturated with 0.17% riboflavin-5-phosphate added every 2 minutes, followed by A-CXL 9 mW/cm2 for 10 minutes. CDVA, medium keratometry value (Kmed), and total corneal morphological irregularity index (CMI) of patients were analyzed before surgery and after 1, 3 and 12 months. A P value of .05 or less was considered statistically significant. Results. 46 eyes of 39 keratoconus patients were treated. At 1 month, the mean CDVA (LogMar) increased from 0.19 ± 0.02 to 0.12 ± 0.02 (P < .05), and the difference remained stable at month 12. Kmax decrease was statistically significant from 57.02 ± 5.65 to 50.21 ± 4.48 (P < .05). CMI decreased significantly from 47.8 ± 2.84 to 30.1 ± 2.4 (P < .01). Conclusions. CCR-CXL protocol is safe and effective in arresting keratectasia progression and increasing corneal optic regularity in keratoconus. These findings showed a significant improvement in CDVA, keratometry values and corneal optical aberrations after being treated with the CCR-CXL protocol. [ABSTRACT FROM AUTHOR]

Carbon plasmas produced by laser ablation can have important applications in the synthesis of nanostructured materials of high current interest (nanotubes, nanowires, graphene) or the deposition of diamond-like thin films. Understanding the fundamental aspects of such transient plasmas in various experimental configurations is useful for optimization of these synthesis/deposition processes. We report here a comprehensive study on the dynamics of an excimer laser produced carbon plasma, including fast photography, space- and time-resolved optical emission spectroscopy, Faraday cup ion current measurements, ablated crater depth profiling. A peculiar V-like shape of the emitting plume is evidenced and explained by the interaction of three plasma structures originating in distinct irradiance areas of the laser spot on the target. The interaction of these structures is also thought to favor an enhanced carbon dimer production, mainly through three-body recombination, at distances significantly higher than previously reported in the literature, which can find technological applications for the efficient deposition of high quality carbon-based nanostructures. [ABSTRACT FROM AUTHOR]

This article analyzes redistribution layer (RDL) technologies needed for 2.5-dimensional (2.5-D) die integration on thin glass interposers and developed using low-cost processes. The design, fabrication, and characterization of a four-metal layer RDL buildup required for wide input/output (I/O) routing at 40-µm bump pitch and a two-metal layer RDL buildup fabricated directly on glass for high-speed, off-package signaling are described. Such RDL technologies are targeted at 2.5-D glass interposer packages to achieve up to 1 Tb/s die-to-die bandwidth and off-interposer data rates > 400 Gb/s, driven by consumer demand of online services for mobile devices. Advanced packaging architectures including 2.5-D and 3-D interposers require fine-line lithography beyond the capabilities of current organic package substrates. High electrical loss and high cost are characteristic of silicon interposers fabricated using back-end-of-line (BEOL) processes that can achieve RDL wiring densities required for 2.5-D die integration. Organic interposers with high wiring densities have also been demonstrated using a single-sided, thin-film process. This article goes beyond silicon and organic interposers in demonstrating fine-pitch RDL on glass interposers fabricated by low-cost, double-side, and panelscalable processes. The high modulus and smooth surface of glass help to achieve lithographic pitch close to that of silicon. Furthermore, the low permittivity and low loss tangent of glass reduce dielectric losses, thus improving high-speed signal propagation. A semiadditive process flow and projection excimer laser ablation were used to fabricate four-metal layer (2 + 0 + 2) fine-pitch RDL and two-metal layer RDL directly on glass. A minimum of 3 µm lithography and 20 µm microvia pitch was achieved. Highfrequency characterization of these RDL structures demonstrated single-ended insertion losses of -0.097 dB/mm at f = 1 GHz and differential insertion losses of -0.05 dB/mm at f = 14 GHz. [ABSTRACT FROM AUTHOR]

We report the fabrication of single wall carbon nanotubes (SWCNTs) by KrF excimer laser ablation under nitrogen atmosphere with a yield of over 70%. We used for the ablation process KrF excimer laser with a 20 ns pulse period and 30 Hz repetition rate, oven temperature 1100 °C, target composition: 0.6 at% Ni, 0.6 at% Co, 98.8 at% C (atomic percentage), 300 L/h nitrogen gas flow rate and a pressure of 500 Torr. Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) measurement results showed that the produced nanotubes have high length, narrow diameter distribution and contain low amount of amorphous carbon and metal catalyst particles. [ABSTRACT FROM AUTHOR]

Pseudopodia are ventral membrane protrusions that extend toward higher concentrations of chemoattractants and play key roles in cell migration and cancer cell invasion. Cancers, including carcinoma and sarcoma, become life threatening when they invade surrounding structures and other organs. Understanding the molecular basis of invasiveness is important for the elimination of cancers. Thus, determining the pseudopodial composition will offer insights into the mechanisms underlying tumor cell invasiveness and provide potential biomarkers and therapeutic targets. Pseudopodial composition has been extensively investigated by using proteomic approaches. A variety of modalities, including gel-based and mass spectrometry-based methods, have been employed for pseudopodial proteomics. Our research group recently established a novel method using excimer laser pulses to selectively harvest pseudopodia, and we successfully identified a number of new pseudopodial constituents. Here, we summarized the conventional proteomic procedures and describe our new excimer laser-assisted method, with a special emphasis on the differences in the methods used to isolate pseudopodia. In addition, we discussed the theoretical background for the use of excimer laser-mediated cell ablation in proteomic applications. Using the excimer laser-assisted method, we showed that alpha-parvin, an actin-binding adaptor protein, is localized to pseudopodia, and is involved in breast cancer invasiveness. Our results clearly indicate that excimer laser-assisted cell etching is a useful technique for pseudopodial proteomics. This article is part of a Special Issue entitled: Medical Proteomics. [ABSTRACT FROM AUTHOR]

Transient Al plasma produced by excimer laser ablation in vacuum was investigated through laser absorption spectroscopy to probe the space-time evolution of neutral species. Spectrally integrating the absorbance, the ground state Al atoms column density was calculated. Typical decreasing trends in time (over a plasma lifetime of about 10 μs) and space (for distances in the range 0.5–8.5 mm from the target surface) were observed. The kinetic temperature of Al ground state species was also estimated from the recorded linewidths, in the assumption of a Doppler broadening mechanism. The resulted values displayed only weak time-fluctuations, while the time-averaged ones showed. a significant drop in few millimeters from the target, similarly to the column density behavior. [Display omitted] • Transient laser-induced Al plasma investigated by laser absorption spectroscopy. • Two absorption maxima assigned to distinct structures of different velocities. • Calculations of column density and kinetic temperature for ground state Al atoms. [ABSTRACT FROM AUTHOR]

Pterygium is among the most frequent indications for extraocular ophthalmic surgery. The main method of pterygium treatment - its excision - is often combined with transplantation, non-transplantation, medication and other methods. However, the frequency of pterygium recurrence can exceed 35%, and the cosmetic and refraction outcomes satisfy neither the patient, nor the surgeon., Purpose: The study analyses the technical capability and feasibility for transplantation of the Bowman's layer in the treatment of recurrent pterygium., Material and Methods: The transplantation of the Bowmen's layer was performed according to the developed technique on 7 eyes with recurrent pterygium (7 patients aged 34 to 63 years). The combined surgery technique consisted of pterygium resection, laser ablation, autoconjunctival plasty, exposure to a cytostatic drug, non-suture transplantation of the Bowman's layer. Maximum length of the follow-up was 36 months. Analysis involved data from refractometry, visometry (without correction and with spectacle correction), and optical coherence tomography of the retina., Results: There were no complications in any of the studied cases. The cornea and the transplant retained transparency throughout the entire follow-up duration. 36 months after surgery mean spectacle-corrected visual acuity amounted to 0.86±0.2, topographic astigmatism - 1.48±1.4 diopters. Recurrence of pterygium was not observed. All patients were satisfied with the cosmetic outcomes of the treatment., Conclusion: Non-suture transplantation of the Bowmen's layer recovers normal anatomy, physiology and transparency of the cornea after repeat surgical intervention for pterygium. No pterygium recurrences were observed throughout the entire follow-up after treatment with the proposed combined technique.

Invasive lobular carcinoma (ILC) is more frequently lymph node positive than is invasive ductal carcinoma (IDC), and ILC cell infiltration shows distinctive histological characteristics, suggesting the action of ILC-specific invasion molecules. To identify such a molecule, we used a proteomic approach in the pseudopodia of MDA-MB-231 breast cancer cells. A pseudopodial constituent was identified using excimer laser ablation, two-dimensional difference gel electrophoresis, mass spectroscopy, and immunocytofluorescence. MDA-MB-231 cells were modified to express various levels of this constituent by transient transfection and were examined for pseudopodia formation and migratory abilities using wound healing and two-chamber assays. Immunohistochemical positivity of human breast cancer cells (56 ILCs and 21 IDCs) was compared with clinicopathological variables. An actin-binding adaptor protein, α-parvin, was found to localize to pseudopodia and to form focal adhesions in cells not induced to extend pseudopodia. Pseudopodial length and density and migratory abilities correlated with α-parvin expression. Twenty-one (37.5 %) ILCs stained positive for α-parvin, whereas the results were negative for all 21 IDCs ( P < 0.001). α-Parvin positivity in ILC was significantly associated with lymphatic invasion ( P = 0.038) and lymph node metastasis ( P = 0.003) in univariate analyses and to lymph node metastasis ( P = 0.020) in multivariate analyses. α-Parvin, a pseudopodial constituent, was found to promote migration of breast cancer cells and to be expressed exclusively by ILC, suggesting that α-parvin is an ILC-specific invasion molecule that may have clinical utility as a biomarker for aggressive subsets of ILC. [ABSTRACT FROM AUTHOR]

Poly(methyl methacrylate) (PMMA) was irradiated using a medical UV-ArF excimer laser operating at the fundamental wavelength of 193 nm. Characterized by a beam diameter of 1.8 mm and energy of 180 mJ with a Gaussian energy profile, it operates in a single mode or at 30 Hz repetition rate. Mechanical profilometry was carried out on ablation craters in order to study the rugosity and the ablation yield in the various operative conditions. Optical transmission and reflection measurements at six wavelengths were conducted in order to characterize the optical properties of the irradiated surfaces. Measured crater depths in PMMA were lower with respect to the forecasted ones in corneal tissue, while the lateral crater aperture was maintained. The rugosity produced at the crater bottom after irradiation was about 0.3 μm, and the ablation yield was about 1015 molecules/laser pulse, while etching depth and diameter show a roughly linear dependence on the number of laser shots. These experiments constitute a base for deeper clinical investigations. [ABSTRACT FROM AUTHOR]

Abstract: The depth-profiles of aged triterpenoid resin films, dammar and mastic, were uncovered by optimized krypton fluoride excimer laser ablation (248nm, 25ns) and the etched varnishes were examined by high performance size exclusion chromatography (HP-SEC). The use of two detectors monitored the molecular weight distribution across depth as a function of absorbance at ultraviolet (240nm) and visible (400nm) light. The absorption of the films at both wavelengths is separated in a small fraction of sesquiterpenoids (200Da), triterpenoid molecules (400/500Da), dimerized and oxidized triterpenoid molecules (900–1000Da) and condensed entities (10–80kDa) that are formed upon the radical polymerization of polycadinene and cis-1,4-poly-β-myrcene, which are the polymers of dammar and mastic, respectively. The results establish the generation of depth-dependent gradients in radical polymerization, condensation and cross-linking across the depth-profiles of the triterpenoid films as a consequence of aging. [Copyright &y& Elsevier]

Abstract: The ablation properties of aged triterpenoid dammar and mastic films were investigated using a Krypton Fluoride excimer laser (248nm, 25ns). Ablation rate variations between surface and bulk layers indicated changes of the ablation mechanisms across the depth profiles of the films. In particular, after removal of the uppermost surface varnish layers there was a reduction of the ablation step in the bulk that was in line with a significant reduction of carbon dimer emission beneath the surface layers as detected by laser-induced breakdown spectroscopy. The results are explicable by the generation of condensation, cross-linking and oxidative gradients across the depth profile of triterpenoid varnish films during the aging degradation process, which were recently quantified and established on the molecular level. [Copyright &y& Elsevier]

Abstract: Recurrent corneal erosion syndrome is a chronic relapsing disease of the corneal epithelium characterized by repeated episodes of sudden onset of pain usually at night or upon first awakening, accompanied by redness, photophobia, and watering of the eyes. Individual episodes may vary in severity and duration. These symptoms are related to corneal deepithelialization in an area in which the epithelium is weakly adhered. It is a frustrating disorder for both the patient and the physician. In the majority of cases, the acute episode is managed by patching, and cycloplegic and topical antibiotic ointment, with prophylactic application of gels during daytime and ointment at night to prevent further erosion. In a minority of cases these measures are insufficient and may need alternative treatment modalities including therapeutic contact lens wear, anterior stromal puncture, superficial keratectomy, Nd:YAG, and most effectively, excimer laser therapy (phototherapeutic keratectomy). [Copyright &y& Elsevier]

Abstract: The deposition of carbon nanotubes and carbon nano-onions at room temperature using excimer laser radiation to ablate mixed graphite–metal targets is described. Our deposition conditions are in contrast to other investigations on the pulsed laser deposition of carbon nanotubes that have employed high temperatures and high pressures. We find that the formation of these carbon nanostructures is dependent on the ambient gas employed during ablation. In the presence of O2 gas, carbon nanotubes and nano-onions are produced, while inert atmospheres such as Ar yield amorphous carbon. High-resolution, in situ, time-resolved emission spectroscopy has been used to track the evolution of species (C2, C3, Ni/Co) in the ablation plume. Spectral fits on low and high-resolution spectra reveal that the vibrational-rotational temperatures for C2 produced in O2 remain at ∼5000K for nearly 20μs but drop rapidly in Ar. Details of the formation of carbon nanotubes and nano-onions, and in situ time-resolved optical emission spectroscopy are described. [Copyright &y& Elsevier]

Abstract: Monazite [(LREE)PO4], a common accessory mineral in magmatic and metamorphic rocks, is complementary to zircon in U–Th–Pb geochronology. Because the mineral can record successive growth phases it is useful for unravelling complex geological histories. A high spatial resolution is required to identify contrasted age domains that may occur at the crystal-scale. Bulk mineral techniques such as ID-TIMS, applied to single monazite grains recording multiple overgrowths or isotope resetting can result in partly scattered discordant analytical points that produce inaccurate intercept ages. Laser ablation (LA)-ICPMS has been demonstrated to be a useful technique for U–Th–Pb dating of zircons, and this study tests its analytical capabilities for dating monazite. A sector field high resolution ICPMS coupled with a 193 nm ArF excimer laser ablation microprobe is capable of achieving a high spatial resolution and producing stable and reliable isotope measurements. The U–Th–Pb systematic was applied to monazite grains from several samples: a lower Palaeozoic lens from high-grade terrains in Southern Madagascar, Neogene hydrothermal crystals from the Western Alps, a Palaeoproterozoic very high temperature granulite from central Madagascar and a Variscan leucogranite from Spain, directly on a polished thin section. The major aim was to compare and/or reproduce TIMS and EMP ages of monazite from a variety of settings and ages. The three independent 206Pb/238U, 207Pb/235U and 208Pb/232Th ratios and ages were calculated. Isotope fractionation effects (mass bias, laser induced fractionation) were corrected using a chemically homogeneous and U–Pb concordant monazite as external standard. This study demonstrates that excimer laser ablation (ELA)-ICPMS allows U–Th–Pb dating of monazite with a high level of repeatability, accuracy and precision as well as rapidity of analysis. A spatial resolution almost comparable to that of EMP in terms of crater width (5 μm) produced precise 208Pb/232Th, 206Pb/238U and 207Pb/235U ratios for dating Palaeozoic to Precambrian monazites. The advantages of (ELA)-ICPMS isotope dating are precision, accuracy and the ability to detect discordance. In the case of late Miocene hydrothermal monazites from the Alps, a larger spot size of 25 μm diameter is required, and precise and accurate ages were obtained only for 208Pb/232Th systematics. Results from the Variscan granite show that in situ U–Th–Pb dating of monazites with (ELA)-ICPMS is possible using a 5 μm spot directly on thin sections, so that age data can be placed in a textural context. [Copyright &y& Elsevier]

Abstract: The C 1s, F 1s, and O 1s electron spectra for polymethyl methacrylate (PMMA) and polytetrafluoroethylene (PTFE) irradiated by KrF excimer laser with 248nm wavelength were analyzed by the X-ray photoelectron spectroscopy (XPS) method. The results show that, after irradiation by the laser, the percentage of the carbon atoms of C–C bond decreases and the percentage of Ccreases for PMMA, while for PTFE percentages of both C–C bond and CF2 group decrease drastically, respectively. Moreover, it was found that C–O bond and other complex carbon–oxygen groups appeared for PTFE. The photon-chemical processes associated with the energy level transitions, energy diversion, and dissociation of bonds in the interaction were theoretically analyzed based on the chemical structures of PTFE and PMMA. Our analyses can successfully explain that PMMA can be effectively etched by KrF excimer laser with 248nm wavelength can efficiently etch the PMMA, but the surface of PTFE can only be modified by it. [Copyright &y& Elsevier]

Abstract: Using masks for laser ablation has proven useful in the fabrication of prototypes for the manufacturing of micro-fluidic devices. In this work, an excimer laser was used to engrave microscopic channels on the surface of polyethylene terephthalate (PET), which showed a high absorption ratio for an excimer laser beam with a wavelength of 248nm. When 50μm wide rectangular microscopic channels were made using a 500×500μm square mask and a magnification ratio of 1/10, ditch-shaped defects were found at both corners. The calculation of the laser beam intensity showed that a coherent image in the PET specimen caused the defects. An analysis based on the Fourier diffraction theory enabled the prediction of a coherent shape at the image plane, as well as a diffracted beam between the mask and the image plane. The analysis also showed that the diameter of the aperture was a predominant factor toward the elimination of ditch-shaped defects in the rectangular microscopic channels on the PET produced by an excimer laser ablation. [Copyright &y& Elsevier]

Abstract: This paper reports on fabrication and design considerations of an integrated folded shorted-patch chip-size antenna for applications in short-range wireless microsystems and operating inside the 5–6GHz ISM band. Antenna fabrication is based on wafer-level chip-scale packaging (WLCSP) techniques and consists of two adhesively bonded glass wafers with patterned metallization and through-wafer electrical interconnects. Via formation in glass substrates is identified as the key fabrication step. Various options for via formation are compared and from these, a 193nm excimer laser ablation is selected for fabrication of the antenna demonstrator. The fabricated antenna has dimensions of 4mm×4mm×1mm, measured operating frequency of 5.05GHz with a bandwidth of ∼200MHz at the return loss of −10dB and a simulated radiation efficiency of 60% were achieved. [Copyright &y& Elsevier]

The formation of microvias in multilayer substrates is a critical factor in microelectronic packaging manufacturing. Such microstructures can be produced efficiently by excimer laser ablation. Thus, laser ablation systems are evolving to a level where the need to offset high capital equipment investment and lower equipment downtime are imminent. This paper presents a methodology for inline failure detection and diagnosis of the excimer laser ablation process. The methodology employs response data originating directly from the equipment and characterization of microvias formed by the ablation process. Neural network (NN) models are trained and validated based on this data to generate evidential belief for potential sources of deviations in the responses. Dempster-Shafer (D-S) theory is adopted for evidential reasoning. Successful failure detection is achieved in 100% of 19 possible failure scenarios. Moreover, successful failure diagnosis is also achieved with only a single false alarm occurring in the 19 failure scenarios. [ABSTRACT FROM PUBLISHER]

Analysis of the thermal effect and machining properties of PC (polycarbonate) and ABS (polyacrylonitrilebutadienestyrene) polymers when ablated using a KrF excimer laser is described. PC has less thermal effect on the geometric distortion than ABS in laser ablation. The cumulative heat during laser ablation results in geometric deformation in ABS micromachining. The number of laser pulses generates a greater geometric deformation in ABS than in PC according to experimental laser ablation observations. The PC ablation rate is proportional to the laser fluence, whereas ABS shows an exponential profile. The pulse repetition rate has no significant influence on PC during laser ablation, but affects the ablated patterns in ABS. During laser ablation, PC does not produce debris on the machining patterns, but debris is produced on the machining patterns with ABS. [ABSTRACT FROM AUTHOR]

We propose a newly designed X-cut lithium niobate (LiNbO3) optical modulator. It has a two-step back-slot structure to satisfy the velocity-matching condition without the buffer layer of silicon dioxide (SiO2). Accordingly, this modulator can achieve low drive voltage and low optical insertion loss. In addition, the dc-drift phenomena due to the buffer layer can be suppressed. This structure is fabricated with micromachining technology using excimer laser ablation. The optical 3-dB bandwidth of the fabricated modulator reaches 30 GHz, and the drive voltage is less than 3 V at 1 kHz. From the measurement of the optical eye diagram at 43.5-Gb/s, clear eye openings were obtained. This modulator is sufficient for 40-Gb/s optical transmission systems. [ABSTRACT FROM PUBLISHER]

An investigation of the use of KrF pulsed excimer laser surface machining of X-cut lithium niobate is presented. Trenches of 20 μm width were formed using a wide range of laser fluences and number of pulses. These trenches were analysed in terms of ablation rate, ablation depth and in particular, laser-induced surface damage. Different forms of observed surface damage have been analysed using SEM imaging and categorised. Possible mechanisms for the damage types are proposed. The effect of depositing a silicon dioxide overlayer on the sample prior to ablation is examined resulting in significant improvement in the quality of the ablated patterns with minimal reduction of ablation rate. [Copyright &y& Elsevier]

Films are deposited on substrates at 20 °C by excimer laser ablation (ELA) of mixture targets of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) with metal powder, PTCDA/M (M=Co, Ni, Fe, W, Cu and Ag) using XeCl and ArF beams. Large amount of fragments with “naked” perylene skeletons can be produced owing to effective elimination of carboxylic dianhydride groups by ELA of PTCDA/Co both with XeCl and ArF beams under optimized ablation conditions.Elimination reaction of side groups of PTCDA is observed for ELA of the targets with metal powder of the iron group, Co, Fe and Ni, especially remarkable for Co and Fe. The film from PTCDA/Ni consists of small particles with the various diameters ranging from 10 to 100 nm as well as that from PTCDA/Co. Morphology like petal of rose can be seen everywhere for the film from PTCDA/Fe. [Copyright &y& Elsevier]

The materials ejected from the hydrated collagen gel by ArF laser (193 nm) ablation were investigated using time-resolved photography, atomic force microscopy (AFM), and FTIR attenuated total reflectance spectroscopy (FTIR-ATR). The time-resolved photography suggested that the characteristics of the ejected materials were affected by the laser fluence and the surface condition, and the driving force of the material ejection would be the cavitation bubble collapse. The AFM and FTIR-ATR measurements demonstrated that measurable-sized materials were ejected by the laser ablation and the structure of the collagen in the ejected materials was partially changed from the original. Some of the ejected materials were found to consist of low molecular weight polypeptides. [Copyright &y& Elsevier]