- 标题
- 摘要
- 关键词
- 实验方案
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A Complex for Diagnostics of Laser Radiation of Semiconductor Targets Excited by a High-Frequency-Modulated Electron Beam
摘要： A complex of equipment for diagnosing the parameters of laser radiation of semiconductor targets, which are excited by high-frequency-modulated electron-beam pulses, is described. The ability to control the shape and duration of laser radiation in the picosecond range via high-frequency modulation of an accelerating-voltage pulse was demonstrated experimentally. A train of laser-radiation pulses with a maximum intensity of up to 2 × 107 W/cm2 was obtained on a cadmium sulfide target (λ = 525 nm).
关键词： picosecond range,cadmium sulfide,semiconductor targets,high-frequency-modulated electron-beam pulses,laser radiation
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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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Efficient 2-W Average Power 206 nm Deep-Ultraviolet Generation from 100-kHz Picosecond Pulses
摘要： We report on the generation of 2 W average power pulsed deep-ultraviolet radiation at 206 nm with few-picosecond pulse duration at a repetition rate of 100 kHz. The 206 nm radiation is derived in three steps by fifth harmonic generation from a 1030-nm, 1.6-ps Yb3+:YAG laser. The steps are second harmonic generation (SHG), fourth harmonic generation (FHG) and sum frequency generation (SFG), see Fig. 1 a). A nonlinear-optical beam flattening scheme together with group velocity matching by substantial pulse front tilts enable, to the author’s best knowledge, a new world record in average output power and conversion efficiency.
关键词： harmonic generation,beam flattening,deep-ultraviolet,picosecond pulses,nonlinear optics
更新于2025-09-16 10:30:52
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Good-Quality and High-Efficiency Dicing for Thick LiNbO3 Wafers Using Picosecond Laser Pulses
摘要： Lithium niobate (LiNbO3) has become popular with applications in electronics and communication industries due to its excellent electro-optical and nonlinear properties. This paper presents the influence of laser power, repetition frequency, number of subpulses, depth of each pass, and scanning velocity in picosecond laser dicing on multiple characteristics of LiNbO3 using the Taguchi method. By means of analysis of variance and analysis of relations between the characteristics, the optimal ps-laser-dicing parameter is obtained with good quality and high efficiency, which is applied to LiNbO3 products. The result indicates that picosecond laser dicing provides an alternative to machine thick LiNbO3 wafers with narrow kerf width, micro chipping, smooth surface, and high productivity.
关键词： thick lithium niobate,picosecond laser,LiNbO3 wafers,laser dicing,dicing quality optimization
更新于2025-09-16 10:30:52
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[IEEE 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) - Berlin, Germany (2019.7.23-2019.7.27)] 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Towards OCT-Navigated Tissue Ablation with a Picosecond Infrared Laser (PIRL) and Mass-Spectrometric Analysis
摘要： Medical lasers are commonly used in interventions to ablate tumor tissue. Recently, the picosecond infrared laser has been introduced, which greatly decreases damaging of surrounding healthy tissue. Further, its ablation plume contains intact biomolecules which can be collected and analyzed by mass spectrometry. This allows for a specific characterization of the tissue. For a precise treatment, however, a suitable guidance is needed. Further, spatial information is required if the tissue is to be characterized at different parts in the ablated area. Therefore, we propose a system which employs optical coherence tomography as the guiding imaging modality. We describe a prototypical system which provides automatic ablation of areas defined in the image data. For this purpose, we use a calibration with a robot which drives the laser fiber and collects the arising plume. We demonstrate our system on porcine tissue samples.
关键词： optical coherence tomography,tissue ablation,mass spectrometry,robot calibration,picosecond infrared laser
更新于2025-09-16 10:30:52
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[Laser Institute of America ICALEO?? 2014: 33rd International Congress on Laser Materials Processing, Laser Microprocessing and Nanomanufacturing - San Diego, California, USA (October 19a??23, 2014)] International Congress on Applications of Lasers & Electro-Optics - Towards the production of glass based printed circuit boards
摘要： This study analyzes laser processing of glass-based printed circuit boards which have the capability to replace conventional substrate materials when electronics are required to operate at elevated temperatures. There is significant potential for glass-based circuit boards within the field of aerospace and electric mobility. The new circuit board concept consists of thin copper-coated borosilicate glass with thicknesses ranging from 150 μm to 500 μm. Conventional mechanical processing of this new circuit boards induces stress on the thin glass which can lead to damage of the substrate. Therefore, laser processing with a picosecond laser source is suggested as a tool within the production process of the new circuit boards. Two necessary processes are investigated using a pulsed picosecond laser with a pulse duration of 7 ps at a wavelength of 515 nm. Precise drill-holes for vertical connections of multilayer boards were produced where chipping at the cutting edge must be avoided. Selective ablation of the copper coating was performed to generate the electrical circuits. The results show that a well-defined ablation process is crucial to achieve adequate electrical isolation without damaging the glass substrate. The study also underlines the huge potential of laser processing with picosecond laser sources, which have proven to be a versatile instrument to drill thin glass and generate electrical circuits by selective ablation.
关键词： copper ablation,picosecond laser,laser processing,borosilicate glass,glass-based printed circuit boards
更新于2025-09-16 10:30:52
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An experimental investigation of laser drilling nitrile butadine (NBR) rubber
摘要： This paper focusses on understanding laser-NBR rubber interactions in particular the effect of laser wavelength and pulse width on material removal and thermal damage. Three lasers with wavelengths at 355 nm, 795 nm and 1064 nm and pulse duration at 30 ns, 10 ps and 130 fs, respectively, have been investigated for their optical absorption, heat conduction and their material removal mechanisms in high aspect ratio drilling of NBR rubber. It is interesting to find that under certain conditions, the ultrashort pulse lasers (both the femtosecond and picosecond lasers) did not lead to better results than the nanosecond UV laser in drilling hole profile (straightness and thermal damage), aspect ratio and amount of the ablated material re-deposition on the substrate surfaces. The results implied that there is heat conduction and thermal damage even with ultrashort laser pulses when the processing conditions are not appropriate. Firing laser pulses intermittently was shown to reduce thermal accumulation. Experimental studies showed that the 355-nm Nd:YAG laser (UV laser) achieved higher material removal rate with high aspect ratio as compared to the ultrashort laser pulses in drilling the NBR substrates.
关键词： NBR rubber,Pulse width effect,Picosecond laser drilling,UV laser drilling,Femtosecond laser drilling
更新于2025-09-16 10:30:52
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Picosecond laser ablation and depth profile of Cu(In, Ga)Se2 thin film layer
摘要： Laser ablation based on picosecond laser was used to achieve the micro-analysis of Cu(In, Ga)Se2 (CIGS) thin film with the ablation crater diameter of 50 μm and the ablation crater central depth of 93 ± 13 nm. We achieved the depth profile of CIGS thin film with different laser shot number. The evolutions of spectral lines intensities of Ca from glass substrate and Ga and In from CIGS thin film layer, and intensity ratios of Ca/Ga and Ca/In could exhibit the change of the ablation volume, which could estimate the thin film thickness of single CIGS thin film layer. The average plasma temperature was calculated to be about 5243 ± 100 K, and the average electron density was calculated to be about 4.5×1016 cm?3. It is shown that our experimental setup is suitable to achieve a precise control and monitor the element compositions in each CIGS thin film layer in the research and in the production of CIGS solar cells.
关键词： Ablation morphology,Electron density,Cu(In, Ga)Se2 thin film,Picosecond laser induced breakdown spectroscopy,Plasma temperature
更新于2025-09-16 10:30:52
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Effect Analysis of Material Properties of Picosecond-Laser Nanoscale Ablation for Acrylonitrile Butadiene Styrene/PolyVinyl Chloride
摘要： ABS/PVC (Acrylonitrile Butadiene Styrene/PolyVinyl Chloride) is suitable for noncontact processing using laser as a tool. Laser-induced optical and thermal energy are utilized to decompose and ablate ABS/PVC. Optical and thermal properties of ABS/PVC play important roles on the laser-induced ablation depth. This paper proposed a model considering the energy balance and decomposition at the ablated interface due to the thermal transport, optical absorption and thermal activation energy in ABS/PVC. The ablation depth predicted by this study is validated by the experimental data. This paper verifies that the laser-pulse ablation rate at the initial processing time is dominated by optical penetration absorption for laser and is linearly proportional to the logarithm of the laser fluence by a ratio factor 'optical absorption length.' This study also analyse how the optical and thermal properties of ABS/PVC influence the variation of the laser-ablated depth with the laser fluences.
关键词： Picosecond Laser,Material Property,ABS/PVC
更新于2025-09-16 10:30:52
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Method for measuring main characteristics of electron-optical cameras
摘要： A procedure is described for determining the basic parameters of linear-sweep electron-optical cameras. The techniques are considered for measuring the limiting temporal resolution and dynamic range of the PS-1/S1 camera using a femtosecond laser and sinusoidal-modulated laser radiation.
关键词： temporal resolution,electron-optical camera,dynamic range,picosecond – femtosecond laser radiation
更新于2025-09-16 10:30:52