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With the large-scale application and high-quality development demands of optical fiber cables, higher requirements have been placed on the corresponding measurement technologies. In recent years, optical fiber testing has played a crucial role in evaluating cable performance, as well as in the deployment, operation, maintenance, fault repair, and upgrade of optical networks. The Optical Time-Domain Reflectometer (OTDR) is a fiber fault diagnostic tool recommended by standards such as the International Telecommunication Union and the International Electrotechnical Commission. It is used to certify the performance of new fiber links and monitor the status of existing ones, detecting and locating fault events with advantages including simple operation, rapid response, and cost-effectiveness. First, this paper introduces the working principle and system architecture of OTDR, along with a brief discussion of its performance evaluation metrics. Next, a comprehensive review of improved OTDR technologies and systems is provided, categorizing different performance enhancement methods, including the enhanced measurement distance with simple structure and low cost in 2024, and the high spatial resolution measurement of optical fiber reflection events and non-reflection events in 2025. Finally, the development trends and future research directions of OTDR are outlined, aiming to achieve the development of low-cost, high-performance OTDR systems.
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http://dx.doi.org/10.3390/s25144284 | DOI Listing |
Transl Vis Sci Technol
September 2025
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, People's Republic of China.
Purpose: The purpose of this study was to estimate the correlations between macular optical coherence tomography (OCT)-derived metrics and incident glaucoma risk in myopic eyes.
Methods: This longitudinal observational study included 24,181 individuals with myopia (spherical equivalence [SE] ≤ -0.5 diopters [D]) from the UK Biobank study.
Chem Rec
September 2025
School of Physics and Mechanics, Wuhan University of Technology, Wuhan, 430070, Hubei, P. R. China.
The development of sensors for monitoring breath acetone, a key biomarker for ketosis in diabetes mellitus, represents a critical frontier in medical diagnostics, promising a painless alternative to invasive blood tests. This review provides a comprehensive and critical evaluation of the state-of-the-art in acetone gas sensing technologies, including chemiresistive, optical, electrochemical, conductometric, and microwave platforms. We focus specifically on recent breakthroughs driven by advanced materials, analyzing how novel nanostructures from two-dimensional (2D) materials such as MXenes to porous metal-organic frameworks (MOFs) are engineered to push performance to clinically relevant parts-per-billion (ppb) sensitivity.
View Article and Find Full Text PDFInt J Biol Macromol
September 2025
Department of Chemical Engineering, Faculty of Engineering, University of Isfahan, Isfahan, Iran.
The persistent presence of Metronidazole (MTZ), a commonly used antibiotic, in water bodies is a serious environmental and health concern because of its genotoxic and carcinogenic potential. Here, we report an effective visible-light photocatalyst system comprising an S-scheme glycine-modified TiO/FeO heterojunction immobilized on chitosan-polyacrylonitrile nanofibers. The photocatalyst nanocomposite was synthesized through a sol-gel and ultrasonication process coupled with electrospinning-assisted immobilization.
View Article and Find Full Text PDFOphthalmol Glaucoma
September 2025
Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA. Electronic address:
Purpose: To assess the clinical outcomes of Hydrus Microstent implantation with cataract extraction for the treatment of open angle glaucoma (OAG) over a maximum of 4 years.
Design: Retrospective, single-center, single-arm, longitudinal cohort study.
Subjects: 308 patients (464 eyes) with OAG who underwent Hydrus Microstent implantation with cataract extraction between February 2019 and December 2021, followed for a median (interquartile range, IQR) of 2.
Int Ophthalmol
September 2025
Beijing Tongren Eye Center, Beijing Tongren Hospital, Beijing key Laboratory of Intraocular Tumor Diagnosis and Treatment, Beijing Ophthalmology and Visual Sciences Key Lab, Medical Artificial Intelligence Research and Verification Key Laboratory of the Ministry of Industry and Information Technolog
Purpose: To analyze macular microvascular networks and investigate correlations between visual acuity and quantitative parameters in patients with Leber's hereditary optic neuropathy (LHON) using optical coherence tomography angiography (OCTA).
Methods: An observational, cross-sectional study was conducted, including 25 eyes from 25 genetically confirmed chronic LHON patients and 25 eyes from 25 age-matched healthy controls. Images were obtained using a spectral domain OCTA system.