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Ce:Nd:YAG continuous-wave solar-pumped laser
摘要： The first emission of a Ce:Nd:YAG solar-pumped laser is reported here, to the best of our knowledge. A solar laser head was composed of a fused silica liquid light guide lens and a conical pump cavity, which coupled and redistributed the concentrated solar radiation from the focal zone of a parabolic mirror into a Ce:Nd:YAG laser rod. The laser output performance of the 5 mm diameter, 30 mm length Ce:Nd:YAG laser rod was compared with that from a 5 mm diameter, 30 mm length Nd:YAG rod. With a solar pump power of 569 W, the Ce:Nd:YAG solar laser emitted 6 W continuous-wave power at 1064nm, corresponding to a collection efficiency of 4.9 W/m2. Even though this power level was lower than the 10 W obtained by using the Nd:YAG rod, the Ce:Nd:YAG laser medium may be an alternative active medium for solar-pumped lasers.
关键词： parabolic mirror,Nd:YAG,solar-pumped laser,Ce:Nd:YAG,cerium
更新于2025-09-16 10:30:52
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The effects of Er:YAG, Nd:YAG, and Diode (940nm) Lasers irradiation on Microtensile bond strength of two steps self-etch adhesives
摘要： Nowadays, studies show the effective laser irradiation role on the adhesion of bonding agents to the dentin. Therefore, the present study was set to find an appropriate protocol for the use of Nd:YAG, Er:YAG, and Diode lasers during the application of two steps self-etch adhesives in direct dental restorations in order to achieve higher microtensile strength.
关键词： Diode laser,Er:YAG,Bond strength,Adhesive,Nd:YAG
更新于2025-09-16 10:30:52
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Effect of nanostructured metal oxides (CdO, Al2O3, Cu2O) embedded in PVA via Nd:YAG pulsed laser ablation on their optical and structural properties
摘要： The physiochemical properties of Polyvinyl Alcohol (PVA) film was enhanced by embedding with nanostructured metal oxides (CdO, Al2O3, and Cu2O) via one-pot and green method, nanosecond Nd:YAG pulsed laser ablation in liquids technique (PLAL). This process was carried by ablation of metal targets (cadmium, copper, and aluminum) immersed in PVA solution by high intensity pulsed laser in the focusing condition. The enhancing of the PVA properties were appeared by studying the structure, optical and morphology of the prepared films before and after embedding by several technique as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–Visible, Photoluminescence (PL), Scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). From structural investigation, the XRD patterns showed a reduction of CdO, Al2O3, and Cu2O nanoparticles within PVA chain. From optical investigation, the interaction and the structural modifications occurred between PVA chains and each metal oxide nanoparticles appeared in stretching vibration bands, the optical energy band gap (Eg) values by using Tauc equation equaled to 2.33, 3.63, and 3.54 eV for the oxide of Cd, Al, and Cu, respectively, are a good agreement with previous work, and the Photoluminescence spectra showed decreasing in emission intensity in the case of embedding with metal oxides. From morphological investigation, the FE-SEM images showed a homogeneous distribution with spherical shape of metal oxides through the polymer of PVA. The qualitative and semi-quantitative elemental analysis of the prepared samples via EDX technique confirmed the embedding of the metal oxide in the PVA structure. This work helps to open the route to produce various properties of PVA by embedded with different nanostructured metal oxides.
关键词： Laser ablation,Al2O3,Nd:YAG,Metal oxides,nanosecond,PVA,Nanomaterials,CdO,Cu2O
更新于2025-09-16 10:30:52
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Fundamentals of three-dimensional Yb-fiber Nd:YAG laser machining of structural bone
摘要： This work aims to understand the fundamental aspects of the laser-bone interaction in three-dimensional laser machining of the bone through an integrated experimental-computational approach. The study introduces 3-dimensional laser machining of bones through multi-laser passes and attempts to establish the dimensional control over the laser-machined cavity through a finite element method based multi-physics computational model. A continuous wave Yb-fiber Nd:YAG laser (λ = 1064 nm) was employed with laser fluences ranging from 5:31 J/mm2 to 25:46 J/mm2 generated in combination of laser power (400 W–700 W) and machining speed (50 mm/s–250 mm/s). In multi-laser pass machining, the optimum fill spacing of 0.2 mm was identified for higher machining rates with low deviation from linearity of machined edge (d = 9 μm). This resulted in high machining rates ranging from 16:49 + 0:2 mm3/s to 45:26 + 0:66 mm3/s for a given range of laser fluence. The optimization for machining efficiency and physical attributes of the machined cavity were comprehended through thermodynamics and kinetics of the laser interaction with the bone based on the computational model for varying laser processing parameters.
关键词： bone,kinetics,Yb-fiber Nd:YAG laser,laser machining,computational model,three-dimensional,thermodynamics
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Terahertz Differential Absorption Spectroscopy Using Multi-Furcated Nd:YAG Microchip Laser for Gas Sensing
摘要： We demonstrate a frequency-domain differential absorption spectroscopy in the terahertz (THz) range for gas sensing applications. Our system is based on an injection-seeded THz-wave parametric generator driven by a multi-furcated Nd:YAG microchip laser. Within a single excitation cycle of the laser, the is-TPG generates up to three narrowband THz-wave pulses that are separated from each other in time by 78 μs and in frequency by 11 GHz, which is due to the spatial hole burning effect in the laser cavity. These pulses can be directly used to measure differential absorption signals, and first and second derivative spectra of target gas molecules without measuring reference spectra.
关键词： Nd:YAG microchip laser,gas sensing,differential absorption spectroscopy,THz-wave parametric generator,terahertz
更新于2025-09-16 10:30:52
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Split-face comparison of the picosecond 1064-nm Nd:YAG laser using a microlens array and the quasi-long-pulsed 1064-nm Nd:YAG laser for treatment of photoaging facial wrinkles and pores in Asians
摘要： Skin photoaging manifests deeper wrinkles and larger pore size. Various lasers have been tried for rejuvenation of photoaging skin, and the quasi-long-pulsed 1064-nm neodymium:yttrium-aluminum-garnet (Nd:YAG) laser is one promising treatment option. New types of laser device are emerging, including devices operating with picosecond pulse duration combined with a microlens array, which are regarded as a new breakthrough for skin rejuvenation. We aimed to evaluate the clinical effectiveness and safety of the picosecond 1064-nm Nd:YAG laser using a microlens array compared with the quasi-long-pulsed 1064-nm Nd:YAG laser in a split-face design. We designed a split-faced, prospective study and enrolled 25 subjects with photoaging facial wrinkles and enlarged pores. Each facial area was randomly assigned to undergo treatment with either the picosecond 1064-nm Nd:YAG laser (Pico-arm) or the quasi-long-pulsed 1064-nm Nd:YAG laser (Quasi-arm). We performed five laser sessions at 2-week intervals, and final results were assessed after 20 weeks after the initial laser session. We used a five-point global assessment scale, wrinkle and pore index derived from 3D camera analysis. We enrolled a total of 25 subjects (24 females and 1 male) with Fitzpatrick skin types III to IV and a mean age of 63.8 ± 5.7 years. After treatment, 54.2% of subjects in the Pico-arm reported at least moderate improvement in visible pores compared with 41.7% of the Quasi-arm (P = 0.001). A total of 12.5% of subjects in the Pico-arm showed moderate improvement in wrinkles versus 4.2% of the Quasi-arm (P = 0.125). There was a 41.3% reduction in the pore index in the Pico-arm compared to a 3.9% increase in the Quasi-arm (P = 0.048). There was a 16.4% reduction in the wrinkle index in the Pico-arm compared with a 0.5% reduction in the Quasi-arm (P = 0.01). Pain assessment score was higher in the Pico-arm than the Quasi-arm (3.65 ± 1.70 vs 1.28 ± 1.28, P = 0.001). No serious adverse events occurred during the study. Our findings suggest that the picosecond 1064-nm Nd:YAG laser with a microlens array is as effective as the quasi-long-pulsed 1064-nm Nd:YAG laser for treatment of photoaging wrinkles and pores.
关键词： Nd:YAG laser,Photoaging,Microlens array,Wrinkle,Picosecond,Pore
更新于2025-09-16 10:30:52
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Nucleate boiling heat transfer performance of different laser processed copper surfaces
摘要： Present study reports the nucleate pool boiling characteristics of micro structured copper surface developed by utilizing two different laser systems, namely, pulsed Nd:YAG laser and continuous wave laser. Tests are conducted at atmospheric pressure and saturation temperature by using water as pool liquid. Enhancement in heat transfer coefficients was observed over all laser processed surfaces. The maximum enhancement in heat transfer coefficient was found to be 136% and 93% for the micro structured surfaces developed by using continuous wave and pulsed laser, respectively, compared to the reference smooth surface. The enhancement in heat transfer performance of micro structured surfaces are due to the presence of surface pores, grooves and micro cavities generated due to laser melting process.
关键词： micro cavities,continuous wave laser,laser ablation,Nd:YAG,nucleate pool boiling,pulsed laser
更新于2025-09-16 10:30:52
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Study on Features of 532nm Laser as Laser Source of Lidar
摘要： The laser source of Lidar usually uses the high power solid laser, the performance of Lidar depends on the laser features, so that to study the laser features is contribute to optimizing the performance of Lidar. Set up and design a pulse solid laser of Nd3+:YAG as the working substance. Through adopting the KTP crystal frequency multiplication technology outside the laser cavity and electro-optic q-switch technique, the maximum dynamic pulse energy of 155mJ and pulse width of 9.6 ns with the 532nm laser is generated. Using the oscilloscope, photoelectric pulse sensor and laser energy meter to measurement the experimental data of the laser source features Through analyze and discuss the experimental data, the relationship between the pulse width, the static and dynamic ratio, the peak power of the pulse Nd3+:YAG laser, the frequency doubling efficiency of the KTP crystal and the input power of laser are given, the solid laser system and the experimental data can provide a basic equipment and reference data to the further study.
关键词： 532nm laser,High power,Laser tracking system,Nd3+:YAG laser
更新于2025-09-16 10:30:52
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Experimental Investigation of Varying Laser Pass on Micro-channel Characteristics of Thick PMMA by Laser Transmission Micro-machining
摘要： Depth of fabrication is an essential characteristic of micro-channels. The laser beam machining process is one of the most suitable processes to fabricate micro-channels. This process has an excellent potential for the fabrication of microfluidic devices which are instrumental for various biomedical applications such as electrophoresis, chromatography, blood protein studies, DNA analysis, etc. In this research work, an attempt has been made to fabricate micro-channels on a thick Polymethyl methacrylate (PMMA) plate at submerged condition by utilizing laser transmission micro-machining process. The laser transmission micromachining operation is conducted here at submerged condition to reduce the adverse thermal effect during machining. Nanosecond pulsed Nd: YAG laser with wavelength in near infrared region has been used here. The depth of micro-channel and heat affected zone (HAZ) width has been taken into account as machining responses. Total 3 sets of experiments which contain 31 experiments in each set have been conducted for three different laser beam pass with the aid of response surface methodology (RSM). The effects of varying laser beam pass on the depth and HAZ width has been studied.
关键词： Nd: YAG laser,laser transmission machining,micro-channeling,PMMA
更新于2025-09-16 10:30:52
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Luminescence declining behaviors in YAG:Ce transparent ceramics for high power laser lighting
摘要： High lumen-density laser lighting has become an advanced lighting technology. However, as an important component, transparent light-conversion materials exhibit low efficiency and luminescence declining behaviors, especially under high power density lasers, seriously restricting their potential applications. Herein, high quality YAG:Ce transparent ceramics (TCs) with different Ce concentrations and sizes were designed and fabricated for comparison with YAG:Ce single crystals to reveal the nature behind the above phenomena under the assistance of different encapsulated models of LED/LD devices. The highest luminous efficiency for the TCs of over 248 lm W?1 was achieved in the LED device, while only 170 lm W?1 could be reached for the LD devices. The strong thermal quenching and concentration quenching worked synergistically to result in the luminescence declining behavior in the 0.5 at% YAG:Ce ceramics, which have 80% and 20% responsibility after smart experimental comparison, respectively. Besides, the potential factors for the low efficiency in TC-based LD lighting were also revealed. Therefore, this work not only shows the optical performance of TCs in LED and LD applications, but also presents how the deep influence factors and excitation models lead to differences in their performance. It significantly reinforces the understanding of fundamental problems for TC-based high power laser lighting. These results are crucial for advancing TC-supported technologies in illumination, projection and scintillation.
关键词： transparent ceramics,concentration quenching,laser lighting,YAG:Ce,luminescence declining,thermal quenching
更新于2025-09-16 10:30:52