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This study utilizes the Kerr effect in the analysis of a pulsed electric field (intensity ~108 V/m, limited by the liquid dielectric strength) in deionized water at the sub-nanosecond time scale. The results provide information about voltage waveforms at the field-producing anode (160 kV peak, du/dt > 70 kV/ns). The analysis is based on detecting the phase shifts between measured and reference pulsed laser beams (pulse width, 35 ps; wavelength, 532 nm) using a Mach–Zehnder interferometer. The signal-to-noise ratio of the detected phase shift is maximized by an appropriate geometry of the field-producing anode, which creates a correctly oriented strong electric field along the interaction path and simultaneously does not electrically load the feeding transmission line. The described method has a spatial resolution of ~1 μm, and its time resolution is determined by the laser pulse duration.

Objective: To assess the effectiveness and safety of combined pulsed-dye laser (PDL) and NAFL for treatment of surgical scars. Summary Background Data: PDL and NAFL have not been compared to healing by time alone. Methods: Randomized controlled, single-blinded clinical trial at an urban, university hospital. Healthy adults' status post skin surgery with primary closure were randomized to either 3 sessions of combination PDL and NAFL every 2 to 8 weeks, or control of no treatment. At baseline and 36-week follow-up, Patient and observer Scar Assessment Scale and Scar Cosmesis Assessment and Rating were completed by participants and blinded physicians. The primary outcome was scar improvement, as measured by the score difference over time. Results: Of 76 participants, 52 completed the study (July 2017 to June 2019). No severe adverse events were reported. Patient and observer Scar Assessment Scale assessments demonstrated improvement in total score in the laser group compared to controls, as reported by patients [mean difference (standard deviation), laser: 12.86 (6.91) vs control: 7.25 (6.34); P = 0.004] and blinded physicians [18.32 (8.69) vs 13.08 (9.63); P = 0.044]. Patients observed a greater improvement in scar thickness [3.68 (2.04) vs 1.88 (1.85); P = 0.002] and stiffness [3.57 (2.78) vs 1.50 (2.11); P = 0.004] with lasers, and physicians reported greater improvement in vascularity [3.71 (1.98) vs 1.71 (1.52); P = 0.0002]. The live Scar Cosmesis Assessment and Rating subscore for erythema improved significantly with lasers [1.04 (0.79) vs 0.42 (0.50); P = 0.001]. Conclusions and Relevance: Combined PDL and NAFL resulted in scar improvement. Scar thickness, stiffness, and erythema were improved. Trial Registration: ClinicalTrials.gov (NCT03057964). [ABSTRACT FROM AUTHOR]

Interest in laser crystallization (LC) of silicon (Si) thin films has been on the rise in fabrication of polycrystalline silicon (pc-Si) based thin/ultrathin photovoltaic solar cells and Si based thin film transistors (TFT). Laser based fabrication of device quality pc-Si thin films at room temperature is expected to be a key enabling technology because of its low energy, material and process time budget. Fabrication of high-quality pc-Si thin films without pre-/post-treatment at large is a disruptive technology which has the potential to revolutionize the Si thin film industry. We hereby describe in detail a multi-wavelength laser processing platform specially developed for crystallization of amorphous silicon (a-Si) thin films into pc-Si thin films. The platform has three main stages. The first stage consists of a nanosecond pulsed ytterbium (Yt3+) doped fibre-laser with a master oscillator power amplifier architecture, operating at a wavelength of 1064 nm with an adjustable repetition rate between 80 kHz−300 kHz. The output beam has a maximum power of 18 W with a pulse energy of 90 µJ. The pulse durations can be set to values between 15 ns−40 ns. The second stage has free-space optical elements for second harmonic generation (SHG) which produces an emission at a wavelength of 532 nm. Conversion efficiency of the SHG is 25% with an output pulse energy of 20 µJ. The platform provides two wavelengths at either 1064 nm or 532 nm in crystallization of a-Si films for different crystallization regimes. The last stage of the platform has a sample processing assembly with a line-focus, which has an x-y motorized stage on a vibration isolated table. Speed of the motorized stage can be set between 1 mm/s−100 mm/s. Stage speed and repetition rate adjustments help to adjust overlap of successive pulses between 97.22−99.99%. Our platform has variety of tune parameters that make it a uniquely flexible system for delicate Si thin film crystallization. A large selection of operational parameter combinations, the wavelength selection and simultaneous x-y scanning capability allow users to crystallize Si films on various substrates optimally. The operation wavelength choice can be done by considering optical absorption and thickness of a-Si films on different types of substrates. Hence, delivering precise amount of absorbed energy in the line-focus irradiation is useful in increasing the average size of crystalline domains; moreover, nucleation of crystallites can be initiated either from the top or bottom interface of the film. Continuous and simultaneous motion of the stage in two dimensions allows to process arbitrary continuous pc-Si geometries in a-Si film. In summary, our multi-wavelength laser processing platform offers all-in-one LC utility for intricate LC-Si processing.

Abstract: Shape memory alloys (SMAs), in particular Nitinol (NiTi), are of increasing interest in research and industry due to their outstanding properties, e.g. the shape memory effect (SME) and high biocompatibility. Obviously, it is necessary to machine these elements from NiTi sheet materials using suitable processing methods that provide high precision and retain the shape memory effect. Pulsed Nd:YAG laser cutting of 1mm thick NiTi shape memory alloys for medical applications (SMA-implants) has been investigated. Due to the local energy input only small heat-affected zones (HAZ) occur and the shape memory properties remain. The influence of key parameters like pulse energy, pulse width, and spot overlap on the cut geometry, roughness and HAZ is shown. [Copyright &y& Elsevier]

The use of laser applications in urology has undergone significant advances over the past 20 years. Laser technology is now used in a wide variety of procedures, and has become the primary treatment modality or standard of care for many urologic conditions. Despite these advances, a number of challenges still face laser utilization in urologic practice. Recent work has illuminated the potential improvement and further optimization of this field. Improvements in types of lasers, the wavelength of energy used, optical fiber delivery systems, precision of laser application and cost reduction have served to further improve laser technology and extend the potential applications. [ABSTRACT FROM AUTHOR]

The developments of laser technology from the cradle of modern physics in 1900 by Planck to its latest medical boundaries is an exciting example of how basic physics finds its way into clinical practice. This article merits the protagonists and their contribution to the steps in this development. The competition between the different research groups finally led to the award of the Nobel Prize to Townes, Basov and Prokhorov in 1964 for the scientific basis on quantum electronics, which led to the construction of oscillators and amplifiers based on the laser-maser principle. Forty-three years after Einstein’s first theories Maiman introduced the first ruby laser for commercial use. This marked the key step for the laser application and pioneered fruitful cooperations between basic and clinical science. The pioneers of lasers in clinical urology were Parsons in 1966 with studies in canine bladders and Mulvany 1968 with experiments in calculi fragmentation. The central technological component for the triumphal procession of lasers in urology is the endoscope. Therefore lasers are currently widely used, being the tool of choice in some areas, such as endoscopical lithotriptic stone treatment or endoluminal organ-preserving tumor ablation. Furthermore they show promising treatment alternatives for the treatment of benign prostate hyperplasia. [ABSTRACT FROM AUTHOR]

BACKGROUND/OBJECTIVE: Keloid scars have been treated in many ways, with varying success. A wide variety of treatments, all in current usage, indicate that no treatment has been shown to be markedly superior to the others. Following the successful treatment of scars using the pulsed dye laser, and with the more traditional intralesional steroid injection, a pilot study was undertaken using a combination of these treatments. METHODS: Recalcitrant keloid scars of 10 patients were managed with a combined treatment modality of pulsed dye laser (PDL) and intralesional steroid. RESULTS: Seven of the patients benefited in terms of the raised nature of the scars being improved by 60%, erythema improved by 40%, and pain/itching by 75%. Three of the patients, who had presternal scars, had no benefit. CONCLUSIONS: Pretreatment with PDL facilitated steroid injection by making the scar oedematous and therefore softer. In addition, we speculate that the benefits of this combined modality are summative, not just adjunctive. This study demonstrates that this treatment is effective for the treatment of keloid scars when other treatments have been unsuccessful. [ABSTRACT FROM AUTHOR]

BACKGROUND: Few therapies are currently available to treat keratosis pilaris atrophicans (KPA), a spectrum of disorders which includes ulerythema ophryogenes and atrophoderma vermiculata. OBJECTIVE: To evaluate the response of KPA to treatment with the pulsed dye laser (PDL) with regard to improvements in erythema and skin roughness, treatment tolerability, and side effects. METHODS: Treatment of all facial areas involved with KPA with the PDL at 585 nm was evaluated in 12 patients. Prior to and after each treatment skin erythema was estimated using an erythema meter, and skin roughness was analysed using micrometer evaluation of a skin surface biopsy taken from the same mapped area and anaysed by computer to calculate the roughness profile. RESULTS: Patients received 2 to 8 treatments with the PDL with energies ranging from 6.0 to 7.5 J/cm[sup 2]. Clinical improvement was noted in all patients with significant reduction in erythema scores. Pre-treatment scores ranged from 4 to 13 (mean 8.3) and post-treatment 0 to 8 (mean 3.1) (P < 0.05). Improvements in skin roughness were clinically apparent in all but two patients, but these were not significant on evaluation of skin surface biopsies. Treatment was generally well tolerated, and side effects other than local pain during treatment were very few. CONCLUSION: PDL treatment appears to be a safe and effective treatment for the erythema associated with KPA but does not give significant improvement in associated skin roughness. [ABSTRACT FROM AUTHOR]