共查询到20条相似文献,搜索用时 187 毫秒
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基于自适应光学的视网膜单细胞光学相干层析成像技术 总被引:2,自引:0,他引:2
介绍了一种基于CCD相机的并行光学相干层析成像技术,将所建立的层析成像系统和自适应光学视网膜相机结合。利用一维光学相干层析系统对人眼视网膜进行追踪并控制相干门在视网膜内的位置,利用基于CCD相机的二维光学相干层析成像系统记录视网膜的干涉图像。用眼模型和牛眼视网膜组织对系统进行了测试,通过将4幅干涉图像的获取时间控制在7 ms以内来减少视网膜运动对成像的影响;系统的轴向点扩展函数和灵敏度分别达到10 μm和76 dB。实验结果表明,所建立的基于自适应光学的视网膜光学相干层析成像系统的空间分辨率和灵敏度远远高于其它基于自适应光学的视网膜成像技术。 相似文献
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提高光学相干层析成像(OpticalCoherenceTomography:OCT)系统纵向分辨率的关键是选取合适的光源,本文将双SLD光源代替传统OCT系统中的单个SLD光源,通过理论分析和计算机仿真,表明双SLD光源能有效提高OCT系统纵向分辨率。 相似文献
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基于相关检测的多通道近红外光组织光学测量系统 总被引:2,自引:0,他引:2
研制了一套基于相关检测技术的三波长多通道近红外光信号采集系统。采用相敏检波模块CD505R有效提高信噪比。Delphi开发的上位机程序通过串口方式与单片机通信。使用光纤传递光源及探测信号,使系统具有更大的灵活性,适用于多种组织光学特性测量方式。模型实验的结果证明该系统准确可靠,前臂阻断实验表明系统对不同深度组织血氧状况具有较好的测量能力。 相似文献
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提出一种基于旋转偏振角的新的偏振光成像方法:改变入射线偏振光偏振角和检偏角,采集样品图像系列,总结出背向散射光2个正交偏振分量的光强差关于入射线偏振光偏振角和检偏角的函数关系式.通过对模拟散射介质,猪肉脂肪,猪肉骨骼肌和牛肉骨骼肌等样品进行实验,论证了偏振差函数式中各个参数与样品光学特性之间的联系,并从中提取出2个相互独立的参数,分别表征样品的纤维方向角和光学各向异性度,从而实现对样品浅表层光学特性进行定量测量.和普通光强图像相比,用这些独立的光学信息生成不同基色的图像,能更直观明了地区分组织结构差异,具有潜在的临床医学应用价值,如成为一种皮肤疾病、皮肤损伤的检测方法. 相似文献
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报道了一种非接触、宽频带、联合微型激光器和低相干迈克尔逊干涉仪的全光学光声显微镜(BD-AOPAM)、光学相干层析系统(OCT)的硬件用于光声信号的检测。目前全光学光声显微镜可检测到的带宽为67 MHz,用碳纤维测得系统的横向分辨率可以达到10.8μm。进一步的,利用包埋头发丝的模拟样品和在体小鼠耳朵血管来验证系统的成像能力。实验结果表明,这种全光学光声显微镜可以在体的实现组织高分辨率的成像,有望成为一种便携式非接触的光声显微镜应用于生物医学当中。 相似文献
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E. Götzinger M. Pircher B. Baumann C. Hirn C. Vass C. K. Hitzenberger 《Journal of biophotonics》2008,1(2):129-139
A polarization‐sensitive spectral domain optical coherence tomography (PS‐SD‐OCT) system is used to measure phase retardation and birefringence of the human retinal nerve fiber layer (RNFL) in vivo. The instrument records three parameters simultaneously: intensity, phase retardation and optic‐axis orientation. 3D data sets are recorded in the optic nerve‐head area of a healthy and a glaucomatous eye, and the results are presented in various ways: En‐face phase‐retardation maps of the RNFL are generated from the recorded 3D data and results are compared with scanning laser polarimetry (SLP). The depth information provided by OCT is used to segment the RNFL in the intensity image and measure the RNFL thickness. From the retardation and thickness data, 2D birefringence maps of the RNFL are derived. Circumpapillary plots of RNFL retardation and thickness obtained by PS‐SD‐OCT are quantitatively compared with those obtained by SLP. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Norman Lippok Boy Braaf Martin Villiger Wang‐Yuhl Oh Benjamin J. Vakoc Brett E. Bouma 《Journal of biophotonics》2019,12(1)
A full quantitative evaluation of the depolarization of light may serve to assess concentrations of depolarizing particles in the retinal pigment epithelium and to investigate their role in retinal diseases in the human eye. Optical coherence tomography and optical frequency domain imaging use spatial incoherent averaging to compute depolarization. Depolarization depends on accurate measurements of the polarization states at the receiver but also on the polarization state incident upon and within the tissue. Neglecting this dependence can result in artifacts and renders depolarization measurements vulnerable to birefringence in the system and in the sample. In this work, we discuss the challenges associated with using a single input polarization state and traditional depolarization metrics such as the degree‐of‐polarization and depolarization power. We demonstrate quantitative depolarization measurements based on Jones vector synthesis and polar decomposition using fiber‐based polarization‐sensitive optical frequency domain imaging of the retinal pigment epithelium in a human eye. 相似文献
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Ekaterina V. Gubarkova Varvara V. Dudenkova Felix I. Feldchtein Lidia B. Timofeeva Elena B. Kiseleva Sergei S. Kuznetsov Boris E. Shakhov Alexander A. Moiseev Valentin M. Gelikonov Gregory V. Gelikonov Alex Vitkin Natalia D. Gladkova 《Journal of biophotonics》2016,9(10):1009-1020
We combined cross‐polarization optical coherence tomography (CP OCT) and non‐linear microscopy based on second harmonic generation (SHG) and two‐photon‐excited fluorescence (2PEF) to assess collagen and elastin fibers and other vascular structures in the development of atherosclerosis, including identification of vulnerable plaques, which remains an important clinical problem and imaging application. CP OCT's ability to visualize tissue birefringence and cross‐scattering adds new information about the microstructure and composition of the plaque. However its interpretation can be ambiguous, because backscattering contrast may have a similar appearance to the birefringence related fringes. Our results represent a step towards minimally invasive characterization and monitoring of different stages of atherosclerosis, including vulnerable plaques. CP OCT image of intimal thickening in the human coronary artery. The dark stripe in the cross‐polarization channel (arrow) is a polarization fringe related to the phase retardation between two eigen polarization states. It is histologically located in the area of the lipid pool, however this stripe is a polarization artifact, rather than direct visualization of the lipid pool.
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An optical method for measuring the birefringence of muscle fibers was developed, which is realized on an automated Linnick interferometer microscope equipped with a laser. It was shown that the method has some advantages over the methods based on measurements of the intensity of light passing through a crossed polarizer, an analyzer, and a fiber (light polarized microscopy). The method involves direct phase measurements of optical path length at the parallel and perpendicular orientations of the polarization plane of probing radiation. The phase image is reconstructed automatically from interferograms with the use of the four-frame phase-shifting algorithm. The phase images of one and the same central part of the fiber at different orientations of the polarization plane represent two-dimensional numerical maps of the optical path length. The subtraction of these images gives a two-dimensional map of the phase shift, which includes information about the birefringence of the fiber. A formula for birefringence measurements was deduced, which has a certain advantage in comparison to that used earlier in that it does not take into account the thickness of a fiber that depends on the measurement point. The birefringence is normalized to a value of the half sum of phases, which are measured separately in the course of the experiment. 相似文献
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We propose a subwavelength quarter-waveplate composed of four L-shaped nanoparticles that act as optical nanoantennas and
investigate its optical properties using the finite-difference time-domain method. When polarization of the incident beam
is parallel to one arm of the antenna, polarization of the scattering light rotates 45° with respect to that of the incident
beam due to the symmetry of the L-shaped nanoantennas. Phase retardation is generated by changing the arm length of the antennas.
The influence of the distance between the L-shaped nanoantennas on the far-field radiation is also discussed. 相似文献
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Ouafa Sijilmassi José Manuel López-Alonso Aurora Del Río Sevilla María del Carmen Barrio Asensio 《Journal of biophotonics》2021,14(1):e202000288
The present article describes the development of a technique, applied to paraffin-embedded tissues, which uses three different wavelengths of monochromatic light (λ1 = 445 nm, λ2 = 540 nm and λ3 = 660 nm) for the measures of the degree of polarization, degree of linear polarization, degree of circular polarization and birefringence, all obtained from measurements of Stokes parameters by using polarized light. The goal of this study was to detect changes in developing embryonic mouse eye when pregnant mice fed diets without folic acid for variable periods compared with a healthy control group. We present a biomedical diagnostic technique based on polarized light detection applied to paraffin-embedded tissues to visualize the structural damage to aid us in the diagnosis before applying other techniques. Through this method, we can visualize and identify which parts of the tissue were altered with respect to the control group. 相似文献
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R Oldenbourg 《Biophysical journal》1991,60(3):629-641
We present an experimental and theoretical study of the phenomenon of edge birefringence that appears near boundaries of transparent objects which are observed with high extinction and high resolution polarized light microscopy. As test objects, thin flakes of isotropic KCl crystals were immersed in media of various refractive indices. The measured retardation near crystal edges increased linearly with both the crystal thickness (tested between 0.3 and 1 micron), and the difference in refractive indices n between crystal (n = 1.49) and immersion liquids (n between 1.36 and 1.62). The specific edge birefringence, i.e., the retardation per thickness and per refractive index difference, is 0.029 on the high refractive index side of the boundary and -0.015 on the low refractive index side. The transition through zero birefringence specifies the position of a boundary at a much higher precision than predicted by the diffraction limit of the optical setup. The theoretical study employs a ray tracing procedure modeling the change in phase and polarization of rays passing through the specimen. We find good agreement between the model calculations and the experimental results indicating that edge birefringence can be attributed to the change in polarization of light that is refracted and reflected by dielectric interfaces. 相似文献
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Quantitative studies on the polarization optical properties of living cells. I. Microphotometric birefringence detection system 总被引:1,自引:1,他引:0 下载免费PDF全文
《The Journal of cell biology》1981,89(1):115-120
A method of polarization optical analysis is described in which phase retardation attributable to birefringence of a minute area in a microscopic object is determined. The optical system consists of a polarizing microscope with "rectified" strain-free lenses, a photoelectric detector to determine the intensity of the light passing through a minute window located at the image plane of the specimen, and a stage that moves the specimen at appropriate velocities for scanning. The error resulting from any flare of light emerging from outside of the area to be measured is minimized by limiting the illuminated area. The specimen can be observed during the measurement of light intensity by illuminating the whole microscope field at a wavelength different from that of the light used for the measurement. The retardation of the specimen is determined by comparing the specimen and background intensities as functions of the azimuth of a Brace-Koherl compensator. Alternatively, retardation is obtained directly from the light intensity at a fixed compensator angle, using the theory of polarization optics. The basal noise level for the present apparatus is approximately 0.03 nm when measuring birefringence of a 4-micron2 area in 0.1 s, using a X 40, NA 0.65 objective. The noise decreases in inverse proportion to the square root of the area times the duration of measurement. 相似文献
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Qi Zhang Peiyu Li Yanying Li Xiaorong Ren Shuyun Teng 《Plasmonics (Norwell, Mass.)》2018,13(4):1129-1134
We propose a universal plasmonic polarization state analyzer consisting of rectangular holes arranged along an Archimedes spiral in silver film. The analyzer can detect different polarization states of light including linear, circular, radial and azimuthal polarizations. The theoretical analysis of its transmitted field is performed on the basis of the dipole radiations, and the analytic expressions of the electric field distributions under different polarized illuminations are provided. The numerical simulations of the near-field transmissions are also conducted to verify the analytic results. The significant differences between the field distributions predict the practicability of the universal plasmonic polarization state analyzer in determining the incident light polarization states. 相似文献
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Bernhard Baumann Danielle J. Harper Pablo Eugui Johanna Gesperger Antonia Lichtenegger Conrad W. Merkle Marco Augustin Adelheid Woehrer 《Journal of biophotonics》2021,14(4):e202000323
Polarization-sensitive optical coherence tomography (PS-OCT) enables three-dimensional imaging of biological tissues based on the inherent contrast provided by scattering and polarization properties. In fibrous tissue such as the white matter of the brain, PS-OCT allows quantitative mapping of tissue birefringence. For the popular PS-OCT layout using a single circular input state, birefringence measurements are based on a straight-forward evaluation of phase retardation data. However, the accuracy of these measurements strongly depends on the signal-to-noise ratio (SNR) and is prone to mapping artifacts when the SNR is low. Here we present a simple yet effective approach for improving the accuracy of PS-OCT phase retardation and birefringence measurements. By performing a noise bias correction of the detected OCT signal amplitudes, the impact of the noise floor on retardation measurements can be markedly reduced. We present simulation data to illustrate the influence of the noise bias correction on phase retardation measurements and support our analysis with real-world PS-OCT image data. 相似文献