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[IEEE 2019 Joint Conference of the IEEE International Frequency Control Symposium anEuropean Frequency and Time Forum (EFTF/IFC) - Orlando, FL, USA (2019.4.14-2019.4.18)] 2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC) - Iodine-Stabilized 633 nm Diode Lasers for Metrology and Interferometry
摘要： For interferometric length measurements and other metrology applications 633 nm helium-neon lasers are still widely used. Here we present two 633 nm diode laser systems stabilized to iodine that can replace this old technique: a compact and robust system based on Doppler-broadened spectroscopy with uncertainty <10-8 for interferometric length measurements and a high-end system with instability below 10-11 based on saturated absorption using the NICE-OHMS method for realization of an optical frequency standard.
关键词： iodine,frequency standard,diode laser,NICE-OHMS,633 nm
更新于2025-09-11 14:15:04
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Evaluation of Chronic Central Serous Chorioretinopathy after Subthreshold Yellow Micropulse Diode Laser Photostimulation at a Wavelength of 577 nm
摘要： Objective: This study evaluated the efficacy and safety of subthreshold yellow diode-laser micropulse 577 nm (SDM) in the treatment of chronic central serous chorioretinopathy (CSCR). Methods: 40 eyes of 40 patients with non-resolving CSCR of >12 months duration were treated with SDM yellow laser (577 nm). Best corrected visual acuity (BCVA) and intraocular pressure (IOP) were measured. Amsler grid screening, ophthalmoscopy, fundus autofluorescence (FAF) and SD-OCT were performed. Follow up measurements were recorded from 3 to 12 months. Results: Restoration of normal macular anatomy was obtained in 85.7% of cases with a significant reduction in mean central foveal thickness (CFT). Mean visual acuity gain was 14.95 ETDRS letters, subjective or objective deterioration after treatment was not recorded in any case. Conclusion: The possibility of favouring reabsorption of subretinal liquid by stimulating the retinal pigment epithelium, even at the fovea, without damaging retinal tissue, opens up new frontiers for the therapy of chronic CSCR.
关键词： Optical coherence tomography,Micropulse diode laser 577 nm,Fundus autofluorescence,Central serous chorioretinopathy
更新于2025-09-11 14:15:04
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Towards Customized Spatial Resolution in TDLAS Tomography and Hugh McCann
摘要： Tunable diode laser absorption spectroscopy (TDLAS) tomography has been widely employed to spatially and temporally resolve gas parameters in combustion processes. The requirements placed on the spatial resolution of a tomographic image vary in industrial applications, depending on the size of the target field and the necessity to detect small features. Based on an optimized beam arrangement, this work proposes a scheme to customize the spatial resolution in the design of TDLAS tomography systems. To the best of our knowledge, the proposed scheme, for the first time, quantifies the impact on the spatial resolution of varying the number of samples of the imaging space, in both angular and linear dimensions. More importantly, the proposed scheme can be used to determine the most effective optical layout that would achieve a desired spatial resolution. The reduction in the system complexity will enable the sensor to be installed in practical combustors while maintaining reliability. Finally, we apply the proposed scheme in a case study based on experimental data previously acquired from an automotive engine.
关键词： tunable diode laser absorption spectroscopy (TDLAS),spatial resolution,combustion diagnosis,tomography,beam arrangement
更新于2025-09-11 14:15:04
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CH <sub/>4</sub> Concentration Distribution in a Semiconductor Process Chamber Measured by the CT-TDLAS
摘要： We measured methane (CH4) concentration distribution in a semiconductor process chamber by using the computed tomography-tunable diode laser spectroscopy (CT-TDLAS). We designed the CT-TDLAS measurement system with a 32-laser-path. The CH4 concentration distribution was measured by the CT-TDLAS based on the 32 absorption spectra which were collected by scanning the laser wavelength around the CH4 absorption peak of 1653.7 nm. We checked linearity of the measurement, validity of the algorithm, and resolution of the computed tomography (CT) reconstructed distribution. In the algorithm check, we measured a simple concentration distribution generated in a ?ve-fold concentric cylinder. Next, we designed a semiconductor process chamber in which the 32-laser-path was installed. After quantitative evaluations of the CT reconstructed distributions by comparing the simulated results of computational ?uid dynamics, we actually measured the CH4 concentration distribution in the chamber when we streamed 10% CH4 from one of four inlet ports and nitrogen from other three ports into the chamber. The measured distributions were obviously different in accordance with the CH4 inlet location, although all the inlet ports were located cyclic-symmetrically. Those results indicated that the ?ow impedances of the four exhaust holes on the susceptor were different depending their locations.
关键词： computed tomography,semiconductor process chamber,CT-TDLAS,methane concentration distribution,tunable diode laser spectroscopy
更新于2025-09-11 14:15:04
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Clinical Outcomes of Micropulsed Transcleral Cyclophotocoagulation in Moderate to Severe Glaucoma
摘要： Purpose: The purpose of this study is to evaluate the safety and effectiveness of a new micropulsed transcleral continuous wave diode laser in a clinical setting of patients diagnosed with open angle glaucoma, ranging from mild glaucoma to severe. Methods: Twenty-six eyes of thirteen patients were treated by a single surgeon at a single private practice center. Results were reviewed retrospectively. Each subject was treated with preset MP3 setting according to recommended treatment guidelines. Results: At baseline, patients were on an average of 3.3 topical glaucoma medications with an average IOP of 25.6 mmHg. At POD1 IOP was reduced by 20%, by 34% at POD7, 8% at POD28 and decreased 30% from baseline at the final postop visit 6-12 months after the procedure. Average medication use decreased from 3.3 to 1.8 from baseline to final post op visit. There were no serious adverse events. Conclusion: Micropulsed transcleral diode laser is a safe and effective alternative for glaucoma therapy for patients with open angle glaucoma. Patients can expect significant IOP lowering along with reduction in number of topical glaucoma medications required for IOP control.
关键词： Transcleral cyclophotocoagulation,Micropulse diode laser MP3 laser,Glaucoma
更新于2025-09-10 09:29:36
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A solid (state) success
摘要： James McKenzie reflects on the impact of the solid-state laser, a device in its infancy when it became the subject of one of the first articles in Physics World. The article discusses the evolution of solid-state lasers from their early days to their widespread use in various applications such as compact discs, DVDs, Blu-ray discs, and optical communications. It also speculates on the future of solid-state lasers and their continued relevance in emerging technologies.
关键词： compact discs,DVDs,Blu-ray discs,solid-state laser,optical communications,diode laser
更新于2025-09-09 09:28:46