Scanning near-field optical images of ordered polystyrene particle layers in transmission and luminescence excitation modes

Scanning near-field optical images of hexagonally close-packed layers of polystyrene spherical particles with a diameter of 1.0 microm have been investigated. The layers were composed of particles that were doped either totally or partially with an organic fluorescent dye. Observations were made in the transmission and luminescence excitation modes with a scanning near-field optical microscope (SNOM) with a spatial resolution shorter than the wavelength of light. The patterns observed in the SNOM images are significantly dependent on the microstructures of layers, that is, the layers are either single or double layered, and the particles are either totally or partially doped. These results are discussed in terms of specific modes of electromagnetic waves transmitting across and along the layers after the local excitation at the tip end of the scanning microprobe.     

Fluorescence multicolor hologram recorded by using a macrolens array

We present a new efficient method for obtaining multicolor digital Fresnel holograms of three-dimensional (3-D) objects emitting incoherent fluorescent light. For each emitted fluorescent light wavelength, a single monochromatic digital modified Fresnel hologram of the 3-D scene is generated. Using a macrolens array, only nine projections of the 3-D scene are captured in a single camera shot and are then digitally processed to yield the hologram. The 3-D reconstructed images from all the monochromatic holograms are composed into a single multicolor image of the 3-D scene. The proposed holographic technique is demonstrated by experiments.     

Spatial Fourier-decomposition optical fluorescen tomography-theoretical investigation

A new three-dimensional (3D) optical fluorescent tomographic imaging scheme is proposed with structured illumination and spatial Fourierdomain decomposition methods for the first time. In this spatial Fourier-decomposition optical fluorescence tomography (SF-OFT), the intensity of focused excitation light from an objective lens is modulated to be a cosine function along the optical axis of the system. For a given position in a two-dimensional (2D) raster scanning process, the spatial frequency of the cosine function along the optical axis sweeps in a proper range while a series of fluorescence intensity are detected accordingly. By making an inverse discrete cosine transformation of these recorded intensity profiles, the distribution of fluorescent markers along the optical axis of a focused laser beam is obtained. A 3D optical fluorescent tomography can be achieved with this proposed SF-OFT technique with a simple 2D raster scanning process.     

“禁戒光”近场光学显微镜原理与系统

扫描近场光学显微术是８０年代后期发展起来的一种分辨率超过衍射极限的新型光学显微镜技术。本文介绍了国外最近出现的“禁戒光”近场光学显微镜系统的工作原理及结构。透射式ＳＮＯＭ中部分光沿着光轴向前传播；部分光沿着大于全内反射临界角的方向传播。前者称为允许光；后者称为禁戒光。应用“禁戒光”近场光学显微镜可同时获得三幅图像，即允许光像、禁戒光像和反映样品表面形貌的剪切力图像。禁戒光图像能够提供很好的对比度和分辨率。     

最近邻域与无邻域算法结合空间滤波实现显微光切片

运用最近邻域与无邻域算法,并结合空间滤波方法,可去除显微切层图像的离焦模糊成份,可获得高成像速度、高质量的显微光切片。对各种显微图像进行了光切片处理,并与由现有去卷积处理、结构光照明等方法获得的光切片图像进行了对比,验证了该算法在去除模糊信息方面有更好的效果,提高了图像处理效率,获得了令人满意的光切片图像。在此基础上研制出了显微光切片图像处理系统。运用最近邻与无最近邻算法,结合空间滤波方法,采用简便可调的卷积模糊算子代替点扩散函数的估计过程,图像处理方便快捷,可较好地去除离焦平面的模糊信息。     

Nanoscale resolution in the focal plane of an optical microscope

Utilizing single fluorescent molecules as probes, we prove the ability of a far-field microscope to attain spatial resolution down to 16 nm in the focal plane, corresponding to about 1/50 of the employed wavelength. The optical bandwidth expansion by nearly an order of magnitude is realized by a saturated depletion through stimulated emission of the molecular fluorescent state. We demonstrate that en route to the molecular scale, the resolving power increases with the square root of the saturation level, which constitutes a new law regarding the resolution of an emerging class of far-field light microscopes that are not limited by diffraction.     

染料掺杂液晶可调谐光纤荧光光源的研究

本文提出了染料掺杂液晶填充空心光纤构造荧光可调谐光源.基于染料分子能级结构理论分析B4400荧光光谱依赖温度的变化特性,采用脉宽8 ns,波长为532 nm YAG倍频脉冲激光器抽运,向列相液晶作基体,实验分析染料B4400掺杂液晶填充空心光纤荧光光谱选择性荧光放大规律及温度调谐特性.结果表明:通过控制染料浓度可控制荧光输出功率水平;当温度升高时,中心波长发生红移,中心波长调谐范围为590—605 nm;荧光谱宽呈单调展宽,调制范围为228—236 nm;染料掺杂液晶填充空心光纤荧光光源可实现一定范围内的温度调谐.     

Quantum teleportation of optical images with frequency conversion

A new version of quantum teleportation of optical images in continuous variables is considered. The new scheme is based on quantum entanglement in continuous variables between light fields of different frequencies and allows wavelength conversion between input and teleported images. The protocol of quantum teleportation with frequency conversion can be used as a combined part of light/matter interface in quantum parallel data processing and in a parallel quantum memory.     

Laser computed tomography of opaque industrial products measured by coherent detection imaging method

The coherent detection imaging method with a low-power He–Ne laser as the source is used to obtain transillumination laser computed tomographic and two-dimensional (2D) images of opaque industrial products such as fluorescent lamps and electric light bulbs. This method is principally based on the optical heterodyne detection technique that has the highest sensitivity along with excellent selectivity in terms of coherence, polarization and high directionality. Structures of the filament and electrode enclosed in the opaque glass were clearly identified with submillimeter resolution.     

Low-cost fibered fluorescence spectroscopic probe designed for biomolecular film characterization

We present a new combination of a fluorescent film deposited onto a chip and a new kind of low-cost optical fluorescence probe. The probe consists of an optical fiber which guides the excitation beam to the chip and a second one which collects the fluorescence light toward a spectrometer slotted into a PC. The resulting data are then processed to extract the pertinent information. This system is designed for the detection of DNA but, at present, we have achieved the detection of functionalized lipidic vesicles and studied the photobleaching process of such films.     

长时程双光子成像技术

双光子成像(Two-Photon Imaging)技术以其优越特性被广泛用于活细胞动态三维成像,但光功率极高的短脉冲光对焦平面荧光分子严重的光漂白极大地影响了双光子长时间成像的图像质量,针对双光子荧光漂白问题,本文提出一种优化光照的双光子(Optimized Lighting-Two Photon,OL-TP)成像技术。通过预扫描获取双光子图像分析高低阈值,以预设的高低阈值为标准优化一幅图像中不同区域的光照时长,利用扫描过程中记录的荧光信息和光照时间信息可以重建OL-TP图像,既保证信噪比又降低荧光漂白。重建的OL-TP图像与传统双光子图像基本一致,信噪比略有降低,但图像并未失真。对110 nm的荧光小球样本分别连续取30幅普通双光子和优化光照的双光子图像,到第30幅图时,重建后的优化光照双光子图像比普通双光子图像荧光漂白降低了28.86%。OL-TP通过优化光照时间大幅降低双光子成像的荧光漂白,使双光子荧光显微镜能够更好地对生物样本进行长时间观测。     

新生儿黄疸治疗仪光源的光生物安全

为了研究不同黄疸治疗仪光源的发光光谱对新生儿产生紫外辐射、热辐射等潜在的光生物安全问题,本文利用光辐射安全测定系统OST-300对传统蓝光荧光灯、普通蓝光LED灯以及经简单遗传算法计算与拟合的蓝光LED灯进行了测试与对比分析。实验结果表明:传统蓝光荧光灯在315,330,365 nm的紫外光处有明显的波峰出现,且峰值波长在365 nm处较为明显;传统蓝光荧光灯在老化后其蓝光光谱光衰严重,且存在大量的红外光线;而基于简单遗传算法计算与拟合的蓝光LED发光光谱与体内胆红素的吸收光谱相吻合,能避免对新生儿的光辐射危害。因此,本文提出的蓝光LED是治疗新生儿黄疸的理想光源。     

Dual-wavelength linear regression phase unwrapping in three-dimensional microscopic images of cancer cells

We present a study of the three-dimensional structure of cancer cells using dual-wavelength phase-imaging digital holographic microscopy. Phase imaging of objects with optical height variation greater than the wavelength of light is ambiguous and causes phase wrapping. By comparing two phase images recorded at different wavelengths, the images can be accurately unwrapped. The unwrapping method is computationally fast and straightforward, and it can process complex topologies. Additionally, the limitations on the total optical height are significantly relaxed. This new methodology is widely applicable to other phase-imaging techniques as well as in applications beyond optical microscopy.     

Scanning Near-Field Optical Microscopy and Microspectroscopy of Green Fluorescent Protein in Intact Escherichia coli Bacteria

Scanning near-field optical microscopy (SNOM) yields high-resolution topographic and optical information and constitutes an important new technique for visualizing biological systems. By coupling a spectrograph to a near-field microscope, we have been able to perform microspectroscopic measurements with a spatial resolution greatly exceeding that of the conventional optical microscope. Here we present SNOM images of Escherichia coli bacteria expressing a mutant green fluorescent protein (GFP), an important reporter molecule in cell, developmental, and molecular biology. Near-field emission spectra confirm that the fluorescence detected by SNOM arises from bacterially expressed GFP molecules.     

Minimizing the effects of unmodulated light and uneven intensity profile on the holographic images reconstructed by pixelated spatial light modulators

A simple and effective approach is proposed to minimize the effect of unmodulated light and uneven intensity caused by the pixelated structure of the spatial light modulator in a holographic display. A more uniform image is produced by purposely shifting the holographic images of multiple reconstructed lights with different incident angles from the zero-diffraction-order and overlapping those selected different orders. The simulation and optical experimental results show that the influence of the zero-diffraction-order can be reduced, while keeping the good uniformity of the target images by this new approach.     

Pulsed ultrasound-modulated light tomography

Ultrasound-modulated light tomography is a new technique that combines laser light and ultrasound to provide a representation of the light density inside turbid media. We present a method that can produce two- or three-dimensional light density representations with standard ultrasonic pulses. This technique should allow simple, direct fusion of ultrasonic images with optical tomography.     

上转换纳米晶标记适配子的新型光开关

适配子是对靶分子有高特异性和亲合力的单链寡核苷酸.由于其结构特性,常用于生物检测.目前的适配子光传感器多采用染料或量子点为标记物,存在背景高,不稳定等缺点.新型的荧光材料上转换纳米晶(UCNPs)因其特殊的发光性质颇受关注.与传统的下转换材料相比,它是近红外光激发,避免产生背景荧光和杂散光.利用聚乙酰亚胺为表面配体,水...     

共焦扫描光学显微镜的高分辨率

讨论了共焦扫描光学显微镜的高分辨率性质,指出共焦扫描显微镜由于采用点探测器,因而视场大大减小,信噪比大大提高,同时每幅图像逐点扫描形成,在光学系统信息能力不变的前提下,系统的空间域通带宽度增加和时域通带宽度减小。因而可成高分辨率的像,特别是其独特的深度分辨率特性使得可以实现光学断层扫描成像。给出了所研制的共焦扫描荧光显微镜所获得光学断层扫描图像     

Quantitative measurements of micro- and macromixing in a stirred vessel using Planar Laser-Induced Fluorescence

The Planar Laser-Induced Fluorescence (PLIF) technique enables measurement of the local degree of deviation in an arbitrary plane inside the mixing vessel. This is achieved by injecting a mixture of an inert dye and a reacting fluorescent into the vessel. The inert dye serves as a tracer for the macromixing. The fluorescent characteristics of the reacting dye change while undergoing a fast chemical reaction with the vessel content and it therefore shows the micromixing indirectly. The concentration fields of the dyes are measured simultaneously. For that a laser beam is expanded into a thin light sheet which illuminates an arbitrary plane in the mixing vessel, exciting the fluorescent dye in this area. The emitted light is detected by a CCD-camera which is positioned vertical to the measurement plane. The fluorescent light passes through two optical filters which are suitable for separating the fluorescent light of the two dyes. The light is then projected on half of the camera chip each so that the same display window is detected twice, and thus the local concentration of the two dyes can be measured simultaneously. Low Reynolds number measurements are performed in a mixing vessel equipped with a Rushton turbine. The lamellar structure is clearly resolved. Areas of micromixing are detected by calculating the local degree of deviation from the concentration fields. These areas are mainly found in the boundary layer of the lamellas.     

新型双通道差分偏振干涉成像系统

针对Wollaston棱镜和Savart偏光镜(SP)组合的差分成像光谱系统存在光线溢出和无法改变系统光程等问题,设计了一种新型双通道差分偏振干涉成像系统.此系统不仅可获取正交偏振图像,还可以通过调整Savart偏光镜的厚度来改变系统光程.介绍了该系统的结构、理论原理,并利用琼斯矩阵推导出四束偏振光线的复振幅及其相干光干涉强度表达式.分析了宽视场Savart偏光镜(WSP)和可调光程的Savart偏光镜(MSP)的分束特性,得出WSP相较于SP具有更好的剪切能力和WSP可优化系统光路的结论.获得了不同楔形结构角下MSP的光程差、横向剪切量随楔形移动量的变化曲线.通过实验验证,获取了不同剪切量下的干涉图像和复色光下平行、垂直分量的空间图像,进而获得了总的强度图像和差分强度图像.得出差分强度图像相较于偏振强度图像具有较高对比度的结论.研究结果对双通道成像光谱系统的性能优化具有一定的参考意义.