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Comparison of laser metal deposition of Inconel 718 from powder, hot and cold wire
摘要： The present paper details first results on laser metal deposition with a new direct diode laser head which allows for coaxial feed of powder, cold- and hot wire material in a single system. The three process variants are compared for laser metal deposition of Inconel 718. The surface appearance, integrity and microstructure of the specimens built with the LMD head are investigated. The presence and removal of the deleterious Laves phase which is detrimental to the mechanical properties is investigated. The results indicate that the new diode laser head allows for a direction-independent LMD process with low oxygen take-up and high surface quality.
关键词： nickel superalloy,Laves phase,direct diode laser,Laser metal deposition
更新于2025-09-12 10:27:22
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Semiconductor Laser Quasi-Array with Phase-Locked Single-Mode Emitting Channels
摘要： The construction of a semiconductor laser with a stripe waveguide is proposed, the geometry of which can make it possible to obtain radiation similar to that of a phase-locked laser array. The requirements for the parameters of the laser quasi-array and the technological feasibility of the proposed approach are discussed.
关键词： diode laser,phase-locked laser array,directional pattern,optical waveguide
更新于2025-09-12 10:27:22
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Utility of High Intensity Laser Therapy Combined with Photobiomodulation Therapy for Socket Preservation After Tooth Extraction
摘要： Objective: High intensity laser therapy (HILT) combined with photobiomodulation therapy (PBMT) using a diode or CO2 laser was administered after extraction of the left ?rst molar in rats. Effects on socket preservation (preservation of the alveolar bone and healing time after extraction) were evaluated histopathologically. Background: Irradiation using a diode or CO2 laser has been shown to hasten wound healing, but the effects remain controversial. Methods: Five-week-old male Wistar rats that underwent extraction of the left maxillary ?rst molar were divided into three groups: diode laser irradiation (diode group), CO2 laser irradiation (CO2 group), and no laser irradiation (control group). HILT (27 J) was performed immediately after tooth extraction to enhance blood coagulation, followed by PBMT (0.7 J) 1 day later to enhance healing. Tissues, including the extraction socket, were removed en bloc 3, 5, 7, 10, and 21 days postextraction to determine the morphological characteristics of wound healing and the distribution of myo?broblasts involved in scar formation. Results: In the diode and CO2 groups, new bone formation and cancellous bone maturation were observed at an early stage of wound healing. The number of myo?broblasts was signi?cantly lower in the laser treatment groups than the control ( p < 0.001), and both treatment groups had a signi?cantly higher alveolar crest height ( p < 0.01), with almost no concavity in the mucosa of the extraction wound. Conclusions: Combined HILT and PBMT following tooth extraction hastened wound healing and preserved alveolar crest height, suggesting a role in socket preservation.
关键词： myo?broblast,carbon dioxide laser,diode laser,socket preservation,tooth extraction,scar tissue,enhanced healing process
更新于2025-09-12 10:27:22
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Successful Treatment of Keratosis Follicularis Spinulosa Decalvans With an 800-nm Diode Laser
摘要： Keratosis follicularis spinulosa decalvans (KFSD) is a rare genodermatosis characterized by widespread keratosis pilaris and progressive cicatricial alopecia of the scalp, eyebrows, and eyelashes; photophobia; and corneal dystrophy. We report a man with KFSD who was successfully treated with laser hair removal on the scalp. A 23-year-old man presented with an 8-year history of hair loss, which had started as a discrete 2.5-cm bald patch on the vertex of the scalp. He gradually developed more patches of alopecia, which expanded and coalesced, and in which the hair never regrew. He complained of itching and tenderness in the affected areas. Furthermore, he had dry skin, with rough-feeling bumps on the upper arms and thighs. As a child, he suffered with photophobia requiring the use of tinted spectacles, but this subsided during his teenage years. He had no other medical history of note and did not take any regular medication. He was of skin phototype II. There was a strong history of male pattern hair loss on the paternal side of the family.
关键词： laser hair removal,diode laser,scarring alopecia,KFSD,Keratosis follicularis spinulosa decalvans
更新于2025-09-12 10:27:22
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Reducing the pitting susceptibility of AISI 304 stainless steel using a hybrid treatment of high-power diode laser and large pulsed electron beam irradiation
摘要： Large pulsed electron beam (LPEB) irradiation has been widely used for surface modification of metals, alloys, polymers, and composites due to its unique interaction mechanisms with materials. The rapid melting and resolidification processes during LPEB irradiation induce phase transformation at the resolidified layer, which enables a simultaneous improvement in mechanical characteristics and chemical stability of metals. However, the generation of craters during LPEB irradiation adversely affects surface quality. It is imperative to minimize crater formation following LPEB irradiation to mitigate pitting corrosion on the surface of stainless steel (SS). In this study, a hybrid surface modification approach using a high-power diode laser (HPDL) and LPEB is proposed to reduce the crater generation during LPEB irradiation. The size and density of craters generated during LPEB irradiation were effectively reduced following the HPDL-LPEB irradiation hybrid surface treatment. The decrease in extent of crater formation and phase transformation has enabled an improvement in corrosion resistance. The ability of the resolidified layer formed after the hybrid HPDL-LPEB irradiation to form a stable passive film shifts the pitting potential from less than 0 mV/SCE (for untreated 304 SS) to more than +800 mV/SCE, which reduced the depth of corroded pits by 75%. The hybrid HPDL-LPEB irradiation decreased non-metallic inclusions, extent of crater formation and the surface roughness, and improved the pitting corrosion and general corrosion resistance.
关键词： High power diode laser,Pitting corrosion,Electron beam,Microstructure,Corrosion resistance,Stainless steels
更新于2025-09-12 10:27:22
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Diode lasers for the treatment of genital warts
摘要： Background: Human papillomavirus (HPV) infections are the most common sexually transmitted diseases leading to genital warts. Developing lesions start off as small papules, which then grow larger and protrude, eventually coalescing into plaque-like formations. Objectives: The aim of this study was to evaluate the efficacy of diode laser coagulation as a treatment for genital warts relative to their number, size, localisation, and recurrence rate. Materials and Methods: Altogether, 45 patients were evaluated in this study. Patients were initially assigned to one of two groups, depending on the size and number of their genital warts, and received a maximum of two laser treatments. Patients were assessed up to three months after intervention. A cure was defined as the complete removal of condylomata. Results: In Group I, 84% of the patients (21/25) were free of recurrence after three months (last follow-up visit). In Group II, 60% of the patients were free of recurrence after three months (12/20 patients); 25% after the first and 35% after the second treatment. Overall, a cure rate of 73% was achieved (33/45 patients). Conclusion: By splitting the laser treatment for multiple, extensive, and/or coalescing genital warts into two sessions, thereby being less destructive to the surrounding tissue, it was possible to achieve comparable cure rates between the two groups. This study indicates that laser treatment is an effective therapy option. Further studies including larger patient cohorts are necessary to ultimately confirm the advantages of laser treatment.
关键词： diode laser,genital warts,condylomata,dermatology,urology
更新于2025-09-12 10:27:22
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Dynamic mode matching of internal and external cavities for enhancing the mode-hop-free synchronous tuning characteristics of an external-cavity diode laser
摘要： This paper proposed an external-cavity diode laser (ECDL) that has low-frequency tuning (< 10 Hz) ability using the synchronous tuning principle. However, during high-frequency tuning, the mechanical vibration of the external-cavity system inherent in the ECDL is excited, which will break the mode matching of the internal and external cavities and greatly decrease the mode-hop-free (MHF) tuning range of the ECDL. To obtain a wide MHF range at high-frequency tuning, we used an active internal-cavity mode control method with an inductance–resistance–capacitance (LRC) filter to implement the dynamic mode matching of the internal and external cavities. After using the LRC filter, the experimental results indicated that the MHF tuning range at high-frequency tuning was significantly improved and a maximum wavelength tuning rate of 6.21 THz/s was obtained at tuning frequency of 30 Hz using an uncoated laser diode with a central wavelength of 785 nm.
关键词： mode-hop-free tuning,dynamic mode matching,synchronous tuning,LRC filter,external-cavity diode laser
更新于2025-09-12 10:27:22
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Development of an interference-filter-type external-cavity diode laser for resonance ionization spectroscopy of strontium
摘要： A frequency tunable external-cavity diode laser (ECDL) using a narrow bandwidth (～0.3 nm) interference filter has been developed for resonance ionization spectroscopy of strontium (Sr) with high isotopic selectivity. Improved wavelength and single mode stabilities of this interference-filter-type ECDL (IF-ECDL) over a commonly used (also home-made) Littrow-type ECDL were theoretically expected and experimentally confirmed by both a wavelength meter and a home-made Fabry-Perot interferometer. The measured spectral profile of the dominant isotope 88Sr using our IF-ECDL in the 689.4 nm intercombination transition shows that the Lorentzian component (～1.3 MHz) of the spectrum width is consistent with the obtained fringe width of the interferometer. High 90Sr isotopic selectivity of ～104 with respect to 88Sr is expected in this transition, which indicates that even if the manufacturing accuracy is not comparable to commercial Littrow-type ECDLs, our compact IF-ECDL having sufficient wavelength stability is a promising laser source for background-free analysis of radioactive 90Sr in marine samples.
关键词： resonance ionization spectroscopy,interference filter,external-cavity diode laser,isotopic selectivity,strontium
更新于2025-09-12 10:27:22
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EXPRESS: Two-Dimensional Temperature Measurement in a High Temperature and Pressure Combustor Using Computed Tomography Tunable Diode Laser Absorption Spectroscopy (CT-TDLAS) with a Wide-Scanning Laser at 1335–1375 nm
摘要： Tunable diode laser absorption spectroscopy (TDLAS) technology is a developing method for temperature and species concentration measurements with the features of non-contact, high precision, high sensitivity, etc. The difficulty of two-dimensional (2D) temperature measurement in actual combustors has not yet been solved because of pressure broadening of absorption spectra, optical accessibility, etc. In this study, the combination of computed tomography (CT) and TDLAS with a wide scanning laser at 1335–1375 nm has been applied to a combustor for 2D temperature measurement in high temperature of 300–2000 K and high pressure of 0.1–2.5 MPa condition. An external cavity type laser diode with wide wavelength range scanning at 1335–1375 nm was used to evaluate the broadened H2O absorption spectra due to the high temperature and high pressure effect. The spectroscopic database in high temperature of 300–2000 K and high pressure of 0.1–5.0 MPa condition has been revised to improve the accuracy for temperature quantitative analysis. CT reconstruction accuracy was also evaluated in different cases, which presented the consistent temperature distribution between CT reconstruction and assumed distributions. The spatial and temporal distributions of temperature in the high temperature and high pressure combustor were measured successfully by CT-TDLAS using the revised spectroscopic database.
关键词： high temperature and high pressure field,TDLAS,computed tomography,2D,Two-dimensional temperature measurement,combustion,CT,tunable diode laser absorption spectroscopy
更新于2025-09-12 10:27:22
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Early tongue carcinomas (clinical stage I and II): echo-guided three-dimensional diode laser mini-invasive surgery with evaluation of histological prognostic parameters. A study of 85 cases with prolonged follow-up
摘要： The management of patients with early stage (cT1–T2) tongue squamous cell carcinoma without clinicoradiologic evidence of neck node metastasis (cN0) has been widely debated over the last 3 decades and still remains controversial. Nevertheless, the identification of patients with low-stage tumours at high-risk for occult cervical metastases is imperative before planning treatments of primary tumours, as well as that of prognostic markers which may possibly select those patients who may benefit of additional workup after surgery in view of the high metastatic potential of the primary tumour. The pre-surgical evaluation of tongue malignant primary tumour (for assessing lateral and deep margins) along with diode laser surgery (with accurate incision, bleeding-free and with reduced/absent post-surgical complications) may lead to a more conservative but equally decisive surgical treatment, also with a greater patient compliance. We studied 85 consecutive cases of cT1–T2 N0 tongue squamous cell carcinoma who had been managed by the following diagnostic/therapeutic protocol: pre-operative high definition ultrasound examination for the evaluation of size and depth, followed by three-dimensional surgical excision by diode laser (wavelength of 800 ± 10 nm, output power of 8 W in continuous wave, flexible optic fibre of 320 μm in contact mode) and detailed histological analyses of well-established prognostic parameters (tumour grade, thickness, depth, front of infiltration and surgical margins) with statistical analysis. No post-surgical photobiomodulation was performed. Overall, 58.82% of patients were stage I, 18% stage II, and the most frequent histotype was squamous cell carcinoma (97.64%). Large nests invasion pattern was observed in 64 cases, expansive pattern in 9, invasion in single cells in 12; front of invasion involved the muscle in 62 cases, vessels in 6, nerves in 15; peritumoural vascular invasion was assessed in 6 patients and perineural invasion in 15. Selective neck lymphadenectomy was performed in 9 cases, and clinically occult node metastases were detected in two cases. At follow-up, 78 patients (98.73%) were alive and free of disease, one patient experienced tumour-related death, while the remaining 6 died for non-disease-related causes. All the histological prognostic parameters were statistically significant (χ2 test; p = 0.05), thus leading to a prognostic weight classification with a three-tiered stratification. On the bases of these results, the authors maintain that the reported diagnostic/therapeutic protocol, including the pre-operative echo-guided three-dimensional evaluation, the following diode laser mini-invasive surgery for tumour excision and the histological examination along with the proposed three-tiered stratification of histological prognostic parameters may allow proper management of clinical stage I and II early tongue carcinomas.
关键词： Ultrasound,Nodal metastasis,Tongue cancer,Diode laser surgery,Neck dissection,Histological prognostic parameters
更新于2025-09-12 10:27:22