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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) - Modeling of the Ultra-Stable Operating Regime in Fourier Domain Mode Locked (FDML) Lasers
摘要： Fourier domain mode locked (FDML) ?ber lasers are broadband wavelength-swept ring systems with record sweep speeds. Lasing is achieved by synchronizing the roundtrip time of the optical ?eld in the ?ber delay cavity with the sweep period of a tunable Fabry-P′erot (FP) bandpass ?lter. Since their invention in 2006, FDML lasers have dramatically enhanced the capabilities of optical coherence tomography (OCT) and various sensing applications. However, the physical coherence limits, such as the maximum achievable coherence length, are yet unknown. An important breakthrough in reaching this limit is a recently experimentally demonstrated highly coherent operation mode over a bandwidth of more than 100 nm [1], referred to as the sweet spot. The sweet spot operation mode is characterized by nearly shot-noise limited ?uctuations in the intensity trace of the laser with signi?cantly enhanced coherence properties, whereas in conventional FDML laser systems the intensity trace is distorted by high frequency noise which negatively affects the coherence length. This ultra-low noise operating regime was generated by an almost perfect compensation of the ?ber dispersion with a manually ?ne tuned chirped ?ber Bragg grating and a highly synchronized sweep rate of the FP ?lter with an accuracy in the range of mHz. Polarization effects were controlled with a polarization maintaining semiconductor optical ampli?er (SOA) gain medium and a polarization controller.
关键词： Fourier domain mode locked (FDML) lasers,sweet spot operation mode,coherence length,semiconductor optical amplifier (SOA),polarization controller,optical coherence tomography (OCT)
更新于2025-09-11 14:15:04
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Ganglion cell layer thickening in well‐controlled patients with type 1 diabetes: an early sign for diabetic retinopathy?
摘要： Purpose: To evaluate early changes in retinal layers using optical coherence tomography (OCT) in patients with long-standing type 1 diabetes (DM1) receiving intensi?ed insulin therapy. Methods: In a cross-sectional case–control study 150 patients with DM1 and 150 age- and sex-matched healthy control participants underwent OCT imaging. Scans of both eyes were analysed for di?erent layers (NFL, GCL (+IPL), INL, outer layer complex (OLC, including OPL, ONL and ELM) and photoreceptors (PR)) in all sub?elds of an ETDRS grid. All analyses were performed semi-automatically using custom software by certi?ed graders of the Vienna Reading Center. ANOVA models were used to compare the mean thickness of the layers between patients and controls. Results: Six hundred eyes with 512 datapoints in 49 b-scans in each OCT were analysed. Mean thickness in patients/controls was 31.35 lm/30.65 lm (NFL, p = 0.0347), 76.7 lm/73.15 lm (GCL, p ≤ 0.0001), 36.29 lm/37.13 lm (INL, p = 0.0116), 114.34 lm/112.02 lm (OLC, p < 0.0001) and 44.71 lm/44.69 lm (PR, p = 0.9401). When evaluating the ETDRS sub?elds separately for clinically meaningful hypotheses, a signi?cant swelling of the GCL in patients could be found uniformly and a central swelling for the OLC, whereas the distribution of NFL and INL thickening suggests that their statistical signi?cance was not clinically relevant. Conclusion: These preliminary results demonstrate that preclinical retinal changes in patients with long-standing DM1 can be found by retinal layer evaluation. However, the changes are layer-speci?c, with signi?cant thickening of the GCL and less so of the OLC suggesting a role as an early sign for di?use swelling and the evolution of DME even in well-controlled diabetes.
关键词： diabetic retinopathy – early detection – early disease – image analysis – OCT
更新于2025-09-11 14:15:04
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Retinal and Choroidal Perfusion Status in the Area of Laser Scars Assessed With Swept-Source Optical Coherence Tomography Angiography
摘要： To evaluate the perfusion status of the retina and choriocapillaris in the area of laser scars on swept-source optical coherence tomography angiography (OCTA) images of eyes previously treated with panretinal photocoagulation (PRP).
关键词： diabetic retinopathy,OCT angiography,laser photocoagulation,choriocapillaris
更新于2025-09-11 14:15:04
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Intravital imaging of adriamycin-induced renal pathology using two-photon microscopy and optical coherence tomography
摘要： Adriamycin (doxorubicin), a common cancer chemotherapeutic drug, can be used to induce a model of chronic progressive glomerular disease in rodents. In our studies, we evaluated renal changes in a rat model after Adriamycin injection using two-photon microscopy (TPM), optical coherence tomography (OCT) and Doppler OCT (DOCT). Taking advantage of deep penetration and fast scanning speed for three-dimensional (3D) label-free imaging, OCT/DOCT system was able to reveal glomerular and tubular pathology noninvasively and in real time. By imaging renal pathology following the infusion of °uorophore-labeled dextrans of di?erent molecular weights, TPM can provide direct views of glomerular and tubular °ow dynamics with the onset and progression of renal disease. Speciˉcally, glomerular permeability and ˉltration, proximal and distal tubular °ow dynamics can be revealed. 6–8 weeks after injection of Adriamycin, TPM and OCT/DOCT imaging revealed glomerular sclerosis, compromised °ow across the glomerular wall, tubular atrophy, tubular dilation, and variable intra-tubular °ow dynamics. Our results indicate that TPM and OCT/DOCT provide real-time imaging of renal pathology in vivo that has not been previously available using conventional microscopic procedures.
关键词： Two-photon Microscopy (TPM),Chronic kidney disease (CKD),Tubular Atrophy,glomerulosclerosis,Optical Coherence Tomography (OCT)
更新于2025-09-11 14:15:04
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Clinical Characteristics, Mutation Spectrum, and Prevalence of ?land Eye Disease/Incomplete Congenital Stationary Night Blindness in Denmark
摘要： PURPOSE. To assess clinical characteristics, foveal structure, mutation spectrum, and prevalence rate of ?Aland eye disease (AED)/incomplete congenital stationary night blindness (iCSNB). METHODS. A retrospective survey included individuals diagnosed with AED at a national low-vision center from 1980 to 2014. A subset of affected males underwent ophthalmologic examinations including psychophysical tests, full-?eld electroretinography, and spectral-domain optical coherence tomography. RESULTS. Over the 34-year period, 74 individuals from 35 families were diagnosed with AED. Sixty individuals from 29 families participated in a follow-up study of whom 59 harbored a CACNA1F mutation and 1 harbored a CABP4 mutation. Among the subjects with a CACNA1F mutation, subnormal visual acuity was present in all, nystagmus was present in 63%, and foveal hypoplasia was observed in 25/43 subjects. Foveal pit volume was signi?cantly reduced as compared to normal (P < 0.0001). Additionally, outer segment length at the fovea was measured in 46 subjects and found to be signi?cantly reduced as compared to normal (P < 0.001). Twenty-nine CACNA1F variations were detected among 34 families in the total cohort, and a novel CABP4 variation was identi?ed in one family. The estimated mean birth prevalence rate was 1 per 22,000 live-born males. CONCLUSIONS. Our data support the viewpoint that AED, iCSNB, and X-linked cone–rod dystrophy 3 are designations that refer to a broad, continuous spectrum of clinical appearances caused in the majority by a variety of mutations in CACNA1F. We argue that the original designation AED should be used for this entity.
关键词： prevalence,iCSNB,?Aland eye disease,CSNB2A,CACNA1F,OCT,CABP4
更新于2025-09-11 14:15:04
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Lateral resolution enhancement using programmable phase modulator in optical coherence tomography
摘要： Adaptive optics plays an important role in the correction of high-order aberrations to enhance lateral resolution. An OCT system coupled with a programmable phase modulator is designed to verify lateral resolution improvement. The Hamamatsu high-resolution, non-pixelized, optically addressed light modulator (PAL-SLM) PPM X7550 series is used to correct aberrations, utilizing a simple method based on phase information from OCT images. The advantages of this method are its high simplicity and low cost. A raster scanning technique is adopted to scan samples covered with scattering suspension. Metal lines covered with scattering suspension are imaged, and a respective correction is applied to remove the aberration. Results demonstrate an improvement in lateral resolution on metal grid samples.
关键词： lateral resolution,PAL-SLM,adaptive optics,aberration correction,OCT
更新于2025-09-11 14:15:04
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Revealing structural modifications in thermomechanical reshaping of collagenous tissues using optical coherence elastography
摘要： Moderate heating of such collagenous tissues as cornea and cartilages by IR-laser irradiation is an emerging technology for non-destructive modification of the tissue shape and microstructure for a variety of applications in ophthalmology, otolaryngology, etc. Post-irradiation high-resolution microscopic examination indicates the appearance of microscopic either spheroidal or crack-like narrow pores depending on the tissue type and irradiation regime. Such examinations usually require special tissue preparation (e.g., staining, drying that affect microstructure themselves) and are mostly suitable for studying individual pores, whereas evaluation of their averaged parameters, especially in situ, is challenging. Here, we demonstrate OCT’s ability to visualize areas of pore initiation and evaluate their averaged properties by combining visualization of residual irradiation-induced tissue dilatation and evaluation of the accompanying Young-modulus reduction by OCT-based compressional elastography. We show that the averaged OCT-based data obtained in situ fairly well agree with the microscopic examination results. The results obtained develop the basis for effective and safe applications of novel non-destructive laser technologies of tissue modification in clinical practice.
关键词： OCT elastography,strain mapping,Optical coherence tomography,laser-tissue interaction,phase-resolved OCT,thermo-mechanical cornea reshaping
更新于2025-09-10 09:29:36
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Assessment of Circumferential Angle Closure with Swept-Source Optical Coherence Tomography: a community based study
摘要： Purpose: To evaluate the diagnostic performance of swept-source optical coherence tomography (SS-OCT, CASIA SS-1000, Tomey Corporation, Nagoya, Japan) for angle closure detection, in comparison with gonioscopy in a community setting. Design: Reliability analysis. Methods: A total of 2027 phakic subjects aged ≥50 years, with no previous history of glaucoma, laser (including peripheral iridotomy), intraocular surgery or ocular trauma, were consecutively recruited from a community polyclinic in Singapore. Gonioscopy was performed by a single trained ophthalmologist. SS-OCT angle scans, which obtain radial scans for the entire circumference of the angle, were analyzed by a single examiner, masked to the subject’s clinical details. On SS-OCT images, angle closure was defined as contact between the iris and any part of the angle wall anterior to the scleral spur. Different cut off values of the degree of circumferential angle closure (≥35%, ≥50% and ≥75%) were taken for analysis to assess SS-OCT performance in detecting angle closure. Results: 1857 subjects (91.6%) were included in the final analysis after excluding poor quality SS-OCT scans. Almost 90% of the subjects were Chinese, with a mean age of 61.8 ± 6.7 years, and more than half were women (63.5%). The overall AUC of SS-OCT manual grading against gonioscopy was 0.84 (CI 95% 0.81-0.88). The prevalence of angle closure on SS-OCT was 26.1% for the ≥35% definition, with an AUC of 0.80 (0.77-0.84), sensitivity of 82.5% (75.3-88.4) and specificity of 78.5% (76.5-80.4). The AC1 statistics for the 2-quadrant gonioscopic definition of angle-closure with corresponding ≥35%, ≥50% and ≥75% angle closure definitions for SS-OCT were good at 0.89 (0.83 - 0.93), 0.88 (0.842 - 0.93) and 0.88 (0.831 - 0.99) respectively. Conclusions: In this large community-based study, SS-OCT exhibited moderate performance for angle closure detection compared to gonioscopy as the reference standard.
关键词： angle closure,community-based study,swept-source optical coherence tomography,gonioscopy,SS-OCT
更新于2025-09-10 09:29:36
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Thickness Measurement and Three-Dimensional Structure Imaging of Oil Slick on Water by Optical Coherence Tomography
摘要： Spectral Domain Optical Coherence Tomography (SD-OCT) with 1300 nm wavelength is employed to detect three-dimensional (3-D) volumetric structure, surficial characteristic and thickness of oil slicks on water surface. The results show that petroleum slick possesses bigger diffusion area but much thinner than diesel slick at the same volume on water. Through reconstructing the thickness of oil slick by single-pixel optical intensity of SD-OCT structure image, the axial depth accuracies of reconstructed dataset image with 2.2 μm in petroleum slick and 2.6 μm in diesel slick were obtained, respectively. To our knowledge, it is the first time to obtain 3-D structure and surficial characteristic of oil slick on water by using SD-OCT imaging, and employing single-pixel optical intensity for reconstructing the thickness of oil slick with higher accuracy.
关键词： Oil slick,Reconstruction thickness,3-D image,SD-OCT
更新于2025-09-10 09:29:36
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[IEEE 2017 XVII Workshop on Information Processing and Control (RPIC) - Mar del Plata (2017.9.20-2017.9.22)] 2017 XVII Workshop on Information Processing and Control (RPIC) - Feasibility and analysis of a system of two in tandem interferometers for optical coherence tomography
摘要： A signal obtained from a combined system of two interferometers of low coherence in the frequency domain is presented and analyzed. This system allows to expand the range of measurement offered by the conventional optical tomography system of a single interferometer with a spectrometer as a detector.
关键词： dynamics range,large depth,optics tomograpfy,FD-OCT,Interferometry
更新于2025-09-10 09:29:36