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Influence of focal spot diameter and beam oscillation on the process efficiency of laser beam welding utilizing a direct diode laser
摘要： Costs of power consumption, efficiency improvement and a green image are increasing issues for automotive manufacturers. One possibility to reduce energy consumption is to increase process efficiency of the established laser beam welding. For this reason this contribution examines whether the laser output power of a direct diode laser can be reduced whilst keeping weld seam volumes constant. This is realized by a reduced spot diameter from initial 664 μm to 368 μm in combination with beam oscillation in order to generate blind seams in 22MnB5 and DC01 steel. It is shown that energy consumption can be reduced significantly.
关键词： Energy efficiency,Oscillation,Focal spot diameter,Direct-diode laser,Automotive
更新于2025-09-12 10:27:22
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Micropulse Transscleral Diode Laser Cyclophotocoagulation in Refractory Glaucoma
摘要： Purpose: To assess the short-term ef?cacy and safety of micropulse transscleral diode laser cyclophotocoagulation (MP-TSCPC) in the management of refractory glaucoma and to compare outcomes based on prior glaucoma surgeries. Design: Retrospective analysis. Participants: Patients with refractory glaucoma who underwent MP-TSCPC at a single institution by 1 of 4 surgeons. Methods: Chart review of cases of MP-TSCPC using the Iridex Cyclo G6 (Mountain View, CA) laser with standard parameters and laser duration at the discretion of each treating physician. Main Outcome Measures: Probability of postoperative success was estimated by the Kaplan-Meier method. Success parameters included intraocular pressure (IOP) 6 to 21 mmHg with or without topical antihypertensive therapy, 20% or more IOP reduction from baseline for any 2 consecutive visits after 3 postoperative months, and no subsequent glaucoma surgery. Results: One hundred sixteen eyes of 116 patients (mean age, 65.8±16.9 years) were included. Baseline IOP was 22.2±7.9 mmHg, and mean postoperative follow-up time was 6.3±3.4 months (range, 3e12 months.) Postoperative IOP at the ?nal follow up was 15.3±6.6 mmHg (P < 0.01), corresponding to a reduction of approximately 6.9 mmHg (31.1%). Most eyes (66.4%) underwent at least 6 months of follow-up. Short-term probability of success was 93.1% at 3 months and 74.3% at 6 months. Eyes that had undergone prior traditional glaucoma surgery (trabeculectomy, tube shunt, excessive pressure-regulating shunt system miniature glaucoma shunt [Alcon, Fort Worth, TX], or a combination thereof) demonstrated a higher probability of success (67.6%) compared with eyes that had not (41.4%; P ? 0.014). The most common complications were decline in best-corrected visual acuity (7.8%) and hypotony (1.7%). Conclusions: Micropulse transscleral diode laser cyclophotocoagulation has a signi?cant short-term ocular hypotensive effect and favorable safety pro?le in eyes with refractory glaucoma. The probability of successful outcome was greater in eyes that had undergone prior traditional glaucoma surgery. Ophthalmology Glaucoma 2019;-:1e11 a 2019 by the American Academy of Ophthalmology
关键词： efficacy,micropulse transscleral diode laser cyclophotocoagulation,intraocular pressure,safety,refractory glaucoma
更新于2025-09-12 10:27:22
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Diode laser spectrometer for high-precision measurements
摘要： The issues of the development, calibration and putting into operation of a diode laser spectrometer for high-precision measurements are considered. The tests rely on the use of an isolated P20 line of the 00031 – 00001 band of the 12C16O2 molecule. The spectrometer error budget is analysed. A software programme for the approximation of a spectral line contour is designed and the procedure is analysed. It is shown that, for a baseline with a relative level of 2.3 ′ 10–5, it is optimal to use no more than six fitting parameters in the line contour approximation. The measured integral intensity of the analytical line constitutes 5.3865(85) ′ 10–23 cm per molecule.
关键词： diode laser,spectral line intensity,spectroscopy
更新于2025-09-12 10:27:22
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Comprehensive analysis of blue diode laser-annealing of amorphous silicon films
摘要： The low temperature polycrystalline silicon (LTPS) method has proved to be a technical breakthrough, accomplishing semiconductor thin films with remarkable mobility for a range of high-performance displays, including liquid crystal display and organic light emitting diodes. However, utilizing a conventional excimer laser source for LTPS incurs high cost. In this paper, we demonstrate a comprehensive analysis of the crystallization mechanism of a-Si film (94 nm) and the thermal deformation of the glass substrate induced by Blue diode Laser Annealing (BLA). BLA provides high quality laterally grown crystals over 4 μm × 10 μm on glass substrates, which were examined by optical microscopy, scanning electron microscopy, and Raman spectroscopy. In addition, the permanent deformation introduced by the annealing process is numerically modeled, instantiating how to control the heat conduction from the thin film that affects the substrate. Our findings reveal that the permanent thermal deformation depth that can be obtained is comparable to the roughness of the silicon film for the optimum scanning speed and laser power. The combination of both experimental and numerical results elucidates the manifested physical mechanisms during the BLA process and provides the guidelines to improve the experimental parameters of this process.
关键词： Lateral grain growth,Glass deformation,Silicon thin film,Low Temperature Polycrystalline Silicon (LTPS),Blue diode laser
更新于2025-09-12 10:27:22
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Development of a near-infrared tunable diode laser absorption spectrometer for trace moisture measurements in helium gas
摘要： There is a demand for water vapor or moisture measurement in gas mixture at trace level from industries like combustion studies, semi-conductor industry, environmental studies, cryogenic services, etc. There are few principles, direct or indirect, to measure moisture—each having individual limitations. Among all, the chilled mirror hygrometer is very accurate but response time is poor; therefore, it is suitable for calibration purposes not for online measurement. An instrument based on near-infrared absorption spectroscopy has been developed and discussed in this article. In this instrument, the laser is modulated with both sinusoidal and slower linear scan, split into two beams: an intense one is passed only through air and the other one through air and the absorption cell of 50 cm length. The balanced detection technique is adopted between the two beams called the reference and the measurement channels, respectively, and the difference signal between the two undergoes the 2-f lock-in detection. This method is good for elimination of moisture present in air and any common-mode noise present in both the channels and as well determines the splitting ratio keeping the absorption cell in vacuum. This method also eliminates the 1-f component present in the signal, which causes asymmetry in the two wings of the 2-f absorption spectra. For computation of absorption spectra, it is found that the Hitran database is sufficient to predict for air as the base gas but Exomol should be used in the cases where helium is the base gas. Simulation and experiment both were performed at different concentration and pressures and the results are found in good agreement for the central spectrum with little difference in wings’ peak. The sensitivity of this instrument achieved at 100 mb pressure in the absorption cell for helium as the base gas with refresh rate of 625 Hz is ～17 ppmv and ～4 ppmv for direct and 2-f measurement, respectively. The applicability of the instrument for air as the base gas is also shown in the paper.
关键词： trace moisture measurements,near-infrared,tunable diode laser absorption spectrometer,helium gas
更新于2025-09-12 10:27:22
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Diode Laser Photocoagulation of Intraoral and Perioral Venous Malformations After Tridimensional Staging by High Definition Ultrasonography
摘要： Objective: To determine optimal settings for use of diode lasers to treat vascular malformations in the head and neck. Background: Diode lasers are generally accepted as effective tools to treat vascular malformations in the head and neck, yet there are no standardized treatment protocols for this treatment approach. Settings for these lasers, in addition to laser type and size and lesion depth are important variables for designing appropriate treatments for vascular malformations. Materials and methods: Vascular venous malformations (VeMs) were classi?ed into ?ve groups according to high-de?nition ultrasound measurements of super?cial dimensions (<1, 1–3, and >3 cm) and lesion extension depth (￡5, and >5 mm). Using a 800 – 10 nm diode laser for surgical procedures, we treated lesions by two different approaches: trans-mucous/cutaneous photocoagulation (8 and 12 W pulsed wave for cutaneous and mucosal lesions, respectively) and intralesional photocoagulation using a laser set to 13 W in the pulsed wave modality to treat both cutaneous and mucosal lesions. Results: We treated 158 vascular VeMs. According to preoperative staging, there were 52 lesions in Group A (super?cial dimension <1 cm), 28 in Group B1 (super?cial dimension from 1 to 3 cm, extension depth ￡5 mm), 16 in Group B2 (super?cial dimension from 1 to 3 cm, extension depth >5 mm), 42 in Group C1 (super?cial dimension >3 cm, extension depth ￡5 mm), and 12 in Group C2 (super?cial dimension >3 cm, extension depth >5 mm). All Group A lesions showed complete healing after a single laser treatment, whereas 7%, 10%, 12%, and 16% of lesions classi?ed in Groups B1, B2, C1, and C2, respectively, required further treatments. Conclusions: The laser settings de?ned in this study were associated with a reduced number of laser applications needed for effective treatment of vascular VeMs. Moreover, the cooling of irradiated tissues, together with prolonged application of a topical regenerative gel, provided good treatment acceptability, reduced the number of postoperative complications, and promoted faster healing of covering tissues.
关键词： diode laser,ultrasonography,vascular venous malformations,photocoagulation
更新于2025-09-12 10:27:22
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Development of an optical pressure measurement system using an external cavity diode laser with a wide tunable frequency range
摘要： Optical pressure measurement systems can precisely measure pressure from vacuum to high pressure with a single apparatus. However, the continuously measurable range without interrupting measurement is limited to less than 1 kPa. In this study, an optical pressure measurement system with a wide continuous measurable range was developed. The optical system can continuously measure a pressure range of 18 kPa when using nitrogen gas by using a Littrow external cavity diode laser as its light source. First, discrete pressure points from vacuum to atmospheric pressure were measured. The repeatability and non-linearity of the differences between the measured values had standard deviations of 0.1 Pa and 0.5 Pa, respectively. Next, a pressure range from 91 kPa to 109 kPa was continuously measured. The results showed that the linearity characteristics of gauges as a function of pressure can be evaluated precisely using our optical pressure measurement system.
关键词： optical pressure measurement,external cavity diode laser,refractive index,wide tunable frequency range,Fabry-Perot cavity
更新于2025-09-12 10:27:22
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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) - Dual-Wavelength Y-Branch DBR-RW Diode Laser at 785 nm with Adjustable Spectral Distance from 0 up to 1.6 nm
摘要： For several applications compact light sources are requested providing two stabilised wavelengths with a narrow linewidth. Applications are shifted excitation Raman difference spectroscopy (SERDS) which separates the Raman lines from disturbing background signals such as ambient daylight or fluorescence or concentration measurements using absorption spectroscopy. Moreover, two slightly different wavelengths are needed for the difference frequency generation into THz radiation. Beside the narrowing and stabilization of the emission wavelength using an internal grating, heater elements above the implemented grating can be used to adjust the spectral distance to meet the demands for the above-mentioned applications. In this contribution, dual-wavelength Y-branch DBR-RW diode lasers emitting at 785 nm with on-chip implemented resistor heaters close to the DBR gratings similar to [1] will be presented. In contrast to the already presented work the heaters are controlled individually and thus the emission wavelength of each laser cavity can be tuned via temperature for each DBR grating separately. This enables the device to provide a flexible spectral distance of the two emission wavelengths in common laser operation of both cavities and fast alteration between both laser lines as recently demonstrated in [2]. The total length of the devices is 3 mm. Two 500 μm long 10th order passive DBR gratings, a 2 mm long S-bend shaped Y-branch coupler section and a 500 μm RW output section form the two laser resonators. The on-chip resistor heater elements are separately controllable as well the two S-bend shaped RW branches and the output RW section. The grating periods are chosen to generate two slightly different emission wavelengths with a spectral distance of 0.6 nm, i.e. 10 cm-1, suitable for SERDS. After a description of the device, electro-optical and spectral properties will be discussed with respect to the above- mentioned applications. In Fig. 1 the power-current characteristic for such dual-wavelength diode lasers is shown. Here the current IY in the Y-coupler was 0 mA, the current Iout in the RW output section was 35 mA and the heatsink temperature is 25°C. Lasing starts for both cavities at about 30 mA with a slope efficiency of 0.6 W/A. An optical output power of more than 200 mW was measured at an injection current of 400 mA. For an output power of 100 mW the spectral tuning with the individual heater elements is shown in Fig. 2 and Fig 3. Here, a flexible spectral range between 0 and 1.6 nm can be obtained while the emission of both branches shows single mode operation with a narrow bandwidth below 11 pm.
关键词： adjustable spectral distance,dual-wavelength,785 nm,Y-branch DBR-RW diode laser,absorption spectroscopy,THz radiation,SERDS
更新于2025-09-12 10:27:22
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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) - Narrower Far Field and Higher Efficiency in 1 kW Diode-Laser Bars using Improved Lateral Structuring
摘要： High power, efficient diode-laser bars with narrow far field angles are sought for many applications, for example in the 9xx nm-range for the pumping of Yb:YAG disc and slab lasers. In previous work, broad-area (BA) diode-laser bars with 4 mm resonator length operated with high conversion efficiency η = 62% at operating power Pop = 1 kW in quasi-continuous wave testing (200 μs, 10 Hz), by using low optical loss and low-resistivity vertical structures and high fill-factors (~70%). Lateral far field (95% power) was θ95% > 10°. However, higher η and narrower θ95% are needed for industrial application, and we seek improvements by altering the lateral bar structure for a fixed vertical design (from [1], wavelength λ = 930 nm, loss αi ≈ 0.4 cm-1). First, narrower θ95% at Pop = 1 kW was sought. In previous studies on 90 μm-wide single emitters, deep implantation through the active region was shown to reduce gain at the emitter edges, suppressing higher-order lateral modes, for smaller θ95%, at the price of reduced η and Pop. A similar implantation approach is assessed here in high fill-factor bars, and the drop in η is mitigated by reducing the implantation depth. Second, higher η at Pop = 1 kW was sought, by increasing the fill-factor, for lower electrical resistance.
关键词： lateral structuring,efficiency,narrow far field,high power,diode-laser bars
更新于2025-09-12 10:27:22
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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) - Widely Tunable Watt-Level MOPA Systems Emitting at 976 nm
摘要： Tunable diode laser sources are key components in absorption spectroscopy, biomedical imaging and in optical telecommunication systems, to mention a few examples. The term tunable refers here to laser sources with a mechanism for precise control of the emission wavelength, while maintaining a narrow spectral linewidth. In addition, multiple applications require high output power with good beam quality. In this work, we present results on recently developed light sources that fulfil these different requirements. These are based on a hybrid master oscillator power amplifier (MOPA) concept, which utilizes a tunable MO combined with a tapered power amplifier (TPA). The MO serves as the wavelength selective element, while the PA ensures amplification to the Watt-level from a nearly diffraction limited beam. These miniaturized systems are constructed on micro benches, on top of 25 mm × 25 mm laser mounts.
关键词： high output power,wavelength tuning,tunable diode laser,MOPA,beam quality
更新于2025-09-12 10:27:22