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排序方式: 共有175条查询结果,搜索用时 31 毫秒
1.
OCT图像散斑的形成机理和清除方法 总被引:4,自引:1,他引:3
根据光相干层析成像(OCT)的光学和光电检测系统特点,结合现有的理论模型,分析了OCT成像和散斑形成机理。指出失去相干性的多次散射光部分会被滤波电路排除,散斑是由高散射组织相干长度之内的不同散射截面上的若干具有nπ光程差的相干散射光彼此叠加形成的。最后讨论了消除散斑的方法。 相似文献
2.
Nowadays in the medical field, imaging techniques such as Optical Coherence Tomography (OCT) are mainly used to identify retinal diseases. In this paper, the Central Serous Chorio Retinopathy (CSCR) image is analyzed for various stages and then compares the difference between CSCR before as well as after treatment using different application methods. The first approach, which was focused on image quality, improves medical image accuracy. An enhancement algorithm was implemented to improve the OCT image contrast and denoise purpose called Boosted Anisotropic Diffusion with an Unsharp Masking Filter (BADWUMF). The classifier used here is to figure out whether the OCT image is a CSCR case or not. 150 images are checked for this research work (75 abnormal from Optical Coherence Tomography Image Retinal Database, in-house clinical database, and 75 normal images). This article explicitly decides that the approaches suggested aid the ophthalmologist with the precise retinal analysis and hence the risk factors to be minimized. The total precision is 90 percent obtained from the Two Class Support Vector Machine (TCSVM) classifier and 93.3 percent is obtained from Shallow Neural Network with the Powell-Beale (SNNWPB) classifier using the MATLAB 2019a program. 相似文献
3.
Nina Kobal Tjaa Kraovec Maja utar Marija Volk Borut Peterlin Marko Hawlina Ana Fakin 《International journal of molecular sciences》2021,22(4)
Mutations in rhodopsin gene (RHO) are a frequent cause of retinitis pigmentosa (RP) and less often, congenital stationary night blindness (CSNB). Mutation p.G90D has previously been associated with CSNB based on the examination of one family. This study screened 60 patients. Out of these 60 patients, 32 were affected and a full characterization was conducted in 15 patients. We described the clinical characteristics of these 15 patients (12 male, median age 42 years, range 8–71) from three families including visual field (Campus Goldmann), fundus autofluorescence (FAF), optical coherence tomography (OCT) and electrophysiology. Phenotypes were classified into four categories: CSNB (N = 3, 20%) sector RP (N = 3, 20%), pericentral RP (N = 1, 6.7%) and classic RP (N = 8, 53.3% (8/15)). The phenotypes were not associated with family, sex or age (Kruskal–Wallis, p > 0.05), however, cystoid macular edema (CME) was observed only in one family. Among the subjects reporting nyctalopia, 69% (22/32) were male. The clinical characteristics of the largest p.G90D cohort so far showed a large frequency of progressive retinal degeneration with 53.3% developing RP, contrary to the previous report. 相似文献
4.
介绍了光学电流互感器的基本原理,与传统的电磁型电流互感器相比,基于Faraday磁旋光效应原理的光学电流互感器在测量原理上不存在测量频带问题,无磁饱和问题。通过比较两种串联运行的电流互感器的现场运行数据,分析其直流分量、基波和谐波含量,得出光学电流互感器具有优良的动态测量特性的结论。 相似文献
5.
6.
Ancong Wang Wenliu Qi Tianxin Gao Xiaoying Tang 《International journal of molecular sciences》2022,23(6)
The growing need to understand the molecular mechanisms of diseases has prompted the revolution in molecular imaging techniques along with nanomedicine development. Conventional optical coherence tomography (OCT) is a low-cost in vivo imaging modality that provides unique high spatial and temporal resolution anatomic images but little molecular information. However, given the widespread adoption of OCT in research and clinical practice, its robust molecular imaging extensions are strongly desired to combine with anatomical images. A range of relevant approaches has been reported already. In this article, we review the recent advances of molecular contrast OCT imaging techniques, the corresponding contrast agents, especially the nanoparticle-based ones, and their applications. We also summarize the properties, design criteria, merit, and demerit of those contrast agents. In the end, the prospects and challenges for further research and development in this field are outlined. 相似文献
7.
B. Chakraborty 《International Journal of Electronics》2013,100(7):671-682
This paper describes a phase locked loop employing a low voltage VCO using modified ECL inverter cells. The VCO circuit employed, features a positive feed back scheme to improve the operating frequency. The phase detector used in the PLL also uses a positive feedback scheme to improve the locked range and to reduce supply voltage of operation of the entire circuit. An improvement of locked range of around 35% was obtained from circuit simulation (using PSPICE) as well as from practical circuit, using discrete components. The minimum supply voltage required here is 2.5 volts. Some biomedical applications of this PLL are also proposed. 相似文献
8.
9.
Muneki Nakada Changho Chong Atsushi Morosawa Keiji Isamoto Takuya Suzuki Hiroyuki Fujita Hiroshi Toshiyoshi 《IEEJ Transactions on Electrical and Electronic Engineering》2014,9(4):448-458
This paper presents a novel device architecture for optically actuated microelectromechanical systems (MEMS) endoscopes for optical coherence tomography (OCT) measurement. A 10‐mW infrared light beam at a wavelength of 1.5 µm is transferred through the single‐mode fiber to provide a scanning MEMS mirror with the drive voltage (maximum 11 V) by exciting a photovoltaic cell, while also providing with a secondary light beam at a wavelength of 1.3 µm for the OCT measurement. An electrostatic vertical comb‐drive optical scanner (1.5 mm × 2.0 mm × 0.5 mm) has been developed by using the deep reactive ion etching (DRIE) of a silicon‐on‐insulator (SOI) wafer. The design of the scanner module is discussed, along with the experimental results of electrostatic operation. An equivalent circuit model for the optical scanner is developed to explain the behavior of the optically powered actuation mechanism, including the hysteresis loop in the frequency response and the voltage dependence of oscillating angle (mechanical peak ±3.2°/7 V around the resonance frequency of 250 Hz). OCT measurement of a tissue is demonstrated to reconstruct the cross‐sectional image of a fingerprint at a resolution of lateral 40 µm × vertical 8 µm and penetration depth of 2.5 mm. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
10.
建立了一个光纤结构的扫描延时的光学相关层析成像(OCT)系统。扫描平台速度不稳会影响成像质量。介绍了用付立叶变换方法将采样信号转换到频域处理的过程中,合理选择信号频域分布的质心位置和频带宽度等参数,可消除由于扫速不稳造成的图像失真。 相似文献