Supercontinuum light source enables in vivo optical microangiography of capillary vessels within tissue beds

This Letter reports on the use of a supercontinuum light source to achieve ultrahigh resolution and ultrahigh sensitive optical microangiography (OMAG) imaging of microcirculations within tissue beds in vivo. After passing through a specially designed optical filter with a passband of 120 nm centered on 800 nm, the light source is coupled into an optic-fiber-based OMAG system that provides a measured axial resolution of ～3 μm over a ranging distance of 2 mm. Within this ranging distance, the system gives an averaged signal-to-noise ratio of 87 dB and a sensitivity roll-off of 7 dB at an A-scan rate of 70 kHz. We demonstrate the capability of the system to visualize a detailed microvascular perfusion map, including the single red blood cells within the capillaries, by imaging a mouse ear flap in vivo.     

Organization and quantification of the elements in the intertubular space in the adult jaguar testis (Panthera onca, LINNAEUS, 1758)

The endocrine portion of mammal testicle is represented by Leydig cells which, together with connective cells, leukocytes, blood and lymphatic vessels, form the intertubular space. The arrangement and proportion of these components vary in the different species of mammals and form mechanisms that keep the testosterone level – the main product of the Leydig cell – two to three times higher in the interstitial fluid than in the testicular blood vessels and 40–250 times higher in these than in the peripheral blood. Marked differences are observed among animal species regarding the abundance of Leydig cells, loose connective tissue, development degree and location of the lymphatic vessels and their topographical relationship with seminiferous tubules. In the jaguar about 13% of the testicular parenchyma is occupied by Leydig cells, 8.3% by connective tissue and 0.3% by lymphatic vessels. Although included in standard II, as described in the literature, concerning the arrangement of the intertubular space, the jaguar has grouped lymphatic vessels in the intertubular space instead of isolated ones. In the jaguar the average volume of the Leydig cell was 2386 μm3 and its average nuclear diameter was 7.7 μm. A great quantity of 2.3 μm diameter lipidic drops was observed in the Leydig cell cytoplasm of the jaguar. The Leydig cells in the jaguar occupy an average 0.0036% of the body weight and the average number per gram of testicle was within the range for most mammals: between 20 and 40 million.     

Full range complex ultrahigh sensitive optical microangiography

This Letter presents a useful method that combines the full range complex Fourier domain optical coherence tomography (OCT) with the ultrahigh sensitive optical microangiography (OMAG) to achieve full range complex imaging of blood flow within microcirculatory tissue beds in vivo. We propose to use the fast scanning axis to realize the full range complex imaging, while using the slow axis to achieve OMAG imaging of blood flow. We demonstrate the proposed method by using a high speed 1310?nm OCT/OMAG system running at 92?kHz line scan rate to image the flow phantoms in vitro, and the blood flows in tissue beds in vivo.     

Efficient delivery of Cre-recombinase to neurons in vivo and stable transduction of neurons using adeno-associated and lentiviral vectors

Background

As development proceeds the human embryo attains an ever more complex three dimensional (3D) structure. Analyzing the gene expression patterns that underlie these changes and interpreting their significance depends on identifying the anatomical structures to which they map and following these patterns in developing 3D structures over time. The difficulty of this task greatly increases as more gene expression patterns are added, particularly in organs with complex 3D structures such as the brain. Optical Projection Tomography (OPT) is a new technology which has been developed for rapidly generating digital 3D models of intact specimens. We have assessed the resolution of unstained neuronal structures within a Carnegie Stage (CS)17 OPT model and tested its use as a framework onto which anatomical structures can be defined and gene expression data mapped.

Results

Resolution of the OPT models was assessed by comparison of digital sections with physical sections stained, either with haematoxylin and eosin (H&E) or by immunocytochemistry for GAP43 or PAX6, to identify specific anatomical features. Despite the 3D models being of unstained tissue, peripheral nervous system structures from the trigeminal ganglion (~300 μm by ~150 μm) to the rootlets of cranial nerve XII (~20 μm in diameter) were clearly identifiable, as were structures in the developing neural tube such as the zona limitans intrathalamica (core is ~30 μm thick). Fourteen anatomical domains have been identified and visualised within the CS17 model. Two 3D gene expression domains, known to be defined by Pax6 expression in the mouse, were clearly visible when PAX6 data from 2D sections were mapped to the CS17 model. The feasibility of applying the OPT technology to all stages from CS12 to CS23, which encompasses the major period of organogenesis for the human developing central nervous system, was successfully demonstrated.

Conclusion

In the CS17 model considerable detail is visible within the developing nervous system at a minimum resolution of ~20 μm and 3D anatomical and gene expression domains can be defined and visualised successfully. The OPT models and accompanying technologies for manipulating them provide a powerful approach to visualising and analysing gene expression and morphology during early human brain development.     

Fast voice-coil scanning optical-resolution photoacoustic microscopy

We developed a photoacoustic imaging system that has real-time imaging capability with optical resolution. The imaging system is capable of scanning at 20 Hz over a 9 mm range and up to 40 Hz over a 1 mm scanning range. A focused laser beam provides a lateral resolution of 3.4 μm as measured in an optically nonscattering medium. Flows of micrometer-sized carbon particles or whole blood in a silicone tube and individual red blood cells (RBCs) in mouse ear capillaries were also imaged in real time, demonstrating the capability to image highly dynamic processes in vivo at a micrometer-scale resolution.     

A New 3D Digitizer by Cutting and Scanning Layer by layer

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A New 3D Digitizer by Cutting and Scanning Layer-by-layer

A crucial element in the reverse engineering process is to obtain 3D data of the part or its CAD model. A new method is presented in this paper, which combines layer-by-layer cutting and scanning on each cross-section of a part with a milling machine and an image scanner respectively. The method can capture the internal and external profile informations of a complex-shaped part at the same precision simultaneously. When data files of 2D edges are imported into the 3D CAD/CAM package, the 3D data or 3D CAD model is acquired. According to the customers' requirements, the system can reach the highest accuracy of 5.4 μm, and a resolution of 2.7 μm in obtaining the 2D edges. The product is completely made now, on which experiments are conducted, which demonstrate the higher accuracy and efficiency.     

高分辨率衍射图形的DMD并行激光干涉直写

通过将数字微反射镜（Digital Micro-mirror Device,DMD）输入阵列图形微缩干涉成像,激光干涉直写系统在光刻胶板上得到缩小的干涉光斑图形,像素特征尺寸3.5 μm,干涉条纹周期1 μm.控制刻蚀深度、干涉条纹取向和DMD输入图形的结构,系统能数字化完成2D/3D、3D光变图像、超微图形文字以及二元光学元件的制作,实现了超高分辨率图形与高效的干涉光刻.给出了实验结果.     

Reflection-mode photoacoustic microscopy using a hollow focused ultrasound transducer for in vivo imaging of blood vessels

A reflection-mode photoacoustic microscope using a hollow focused ultrasound transducer is developed for highresolution in vivo imaging.A confocal structure of the laser and the ultrasound is used to improve the system resolution.The axial and lateral resolutions of the system are measured to be ～ 32 μm and ～ 58 μm,respectively.Ex vivo and in vivo modes are tested to validate the imaging capability of the photoacoustic microscope.The adjacent vein and artery can be seen clearly from the reconstructed photoacoustic images.The results demonstrate that the reflectionmode photoacoustic microscope can be used for high-resolution imaging of micro-blood vessels,which would be of great benefit for monitoring the neovascularization in tumor angiogenesis.     

Development of phase-stabilized swept-source OCT for the ultrasensitive quantification of microbubbles

This paper describes the development of a novel-phase resolved system based on swept-source optical-coherence tomography (SSOCT) for the ultrasensitive imaging and monitoring of gas microbubbles in aqueous media. The developed phase-stabilized SSOCT (PhS-SSOCT) system has an axial resolution of 10 μm, a phase sensitivity of 0.03 rad, an imaging depth of up to 6 mm in air, and a scanning speed of 20 kHz for a single A line. The performance of the sensing system was evaluated in water-containing gas microbubbles with a different diameter. The obtained results demonstrate that bubbles with a diameter greater than 10 μm could be detected by both structural imaging and phase response, whereas bubbles with diameters of less than 10 μm could be detected by the phase response of the SSOCT with a high sensitivity. The accuracy for the measurement of the diameter of gas microbubbles is limited to 10 μm in structural imaging and 0.01 μm in phase-sensitive monitoring. The results from this study indicate that PhS-SSOCT could be used to detect fast-moving microbubbles in aqueous solutions and ultimately could be applied for rapid assessment in biofluids (e.g., blood) and tissues (e.g., skin) in vivo.     

One-dimensional Wolter optics with a sub-50 nm spatial resolution

We studied an imaging system consisting of an elliptical mirror and a hyperbolic mirror [i.e., one-dimensional (1D) Wolter optics] to realize an achromatic full-field hard x-ray microscopy with a resolution better than 50 nm. We report the performance of this 1D Wolter optical system when the mirrors were ultraprecisely figured by elastic emission machining. Experiments to form a demagnified image (demagnification factor of 385) of a 10 μm slit were conducted at an x-ray energy of 11.5 keV at BL29XUL of SPring-8. The system could form a demagnified image with a resolution better than 50 nm over a 12.1 μm field.     

适用于激光聚变实验的短焦距高放大倍率Wolter显微镜设计

围绕内爆压缩及阻滞阶段相关物理实验的诊断需求,提出了一种满足阿贝正弦条件的短焦距高放大倍率Wolter-Ⅲ型X射线显微镜的光学设计。详细介绍了Wolter-Ⅲ型显微镜的结构特点和设计方法,与Wolter-Ⅰ型相比可以通过将主平面向靠近物点方向移动的方式减小系统焦距,从而获得更大的放大倍数,实现显微镜与探测器的像质匹配,提高诊断系统的空间分辨。由光线追迹可以得出,在±190 μm的视场范围内,空间分辨率优于3 μm;在±240 μm范围内分辨率优于5 μm;在±300 μm范围内分辨率优于8 μm,几何集光立体角约为5×10?6 sr。     

用光学记录速度干涉仪测量自由面速度

 建立了一套光学记录速度干涉仪系统(ORVIS)，用于测量强激光产生的冲击波状态方程中的自由面速度。该光学记录速度干涉仪系统的时间分辨率为179 ps，可以测量自由面速度随时间变化的整个过程。在天光KrF高功率准分子激光装置上进行激光打靶实验，激光波长248.4 nm，脉冲宽度25 ns，最大输出能量158 J。在激光功率密度为6.24×10¹¹W·cm^-2的条件下，测得厚20 μm铁膜的自由面速度可达3.86 km/s；在激光功率密度为7.28×10¹¹W·cm^-2条件下，100 μm铝膜（靶前有100 μm的CH膜作为烧蚀层）的自由面速度可以达到2.87 km/s。     

基于辅助光学系统的KB显微镜瞄准方法

 研究了利用辅助可见光系统精确瞄准KB显微镜物点的方法。设计了工作能点8 keV的周期多层膜KB显微镜系统,通过光线追迹和X射线成像实验,得到5 μm空间分辨率所对应的视场和景深,进而计算出诊断实验对应的指向和景深要求。基于KB系统的物像关系和精度要求,设计了辅助的可见光成像系统,实现了可见光系统与X射线KB系统间的等效瞄准,利用耦合好的系统进行了瞄准和X射线成像实验。实验结果表明:辅助光路可以实现±20 μm的垂轴面和±300 μm的轴向定位精度,满足KB显微镜的瞄准要求。     

High-resolution cardiac imaging using an interleaved 3D double slab technique

A three-dimensional (3D) gradient-echo sequence with interleaved double-slab excitation was developed and optimized for the requirements in pediatric cardiac imaging. For this purpose high contrast between blood and myocardium signal should be obtained without the use of contrast agents. An acceptable measuring time for a large region examined with high spatial resolution should be achieved as well, especially with regard to the small structures of the heart and vessels of infants. The presented approach works with gradient moment nulling and a short echo time of 5.5 ms resulting in generally high signal intensity and only minor signal losses due to turbulent flow. The sequence allows simultaneous ECG-gated recording of two separately excited slabs with small thickness (10 mm) and with a distance of several centimeters between them. Thus, common effects of presaturation in 3D imaging can be avoided, although a relatively short measuring time is achievable. In order to get a 3D data set with good signal homogeneity of blood and of the other structures across a large volume of interest several double-slab measurements with suitable positions must be performed. The latter aspect is especially important for postprocessing techniques as multiple planar reconstruction and maximum intensity projection. Examples of applications of the new technique and appropriately postprocessed images are presented allowing demonstration even of subtle cardiac malformations.     

Passive ranging and three-dimensional imaging through chiral phase coding

We present a method for single-image passive ranging and three-dimensional (3D) imaging in incoherent light based on chiral phase coding. A chiral linear phase variation across the aperture of an optical system results in a frequency response with a characteristic pattern of fringes such that the spatial period and inclination of the pattern depend on the focusing error. From this dependency, the absolute focusing error and, hence, the distance to the object can be found. In the experiments a resolution of ~1.4 μm is achieved with a 20 mm aperture lens in a 4 mm interval at a distance of 140 mm from the lens. A resolution of ~0.7 mm is obtained at a distance of ~11 m with the range finder employing two 25.4 mm spherical mirrors spaced apart by ~140 mm. We also demonstrate 3D imaging of weakly textured objects.     

三维时域散斑动态干涉测量系统的集成化设计

三维电子散斑干涉技术（3D ESPI）具有非接触、高精度、高灵敏度和全场测量等优点，被广泛应用于许多领域。为了实现非接触动态全场三维测量，设计并建立了一个紧凑、完备的三维测量系统。用一个多波长光纤耦合激光器代替3个独立光源，产生的离面、面内散斑干涉图仅用一台彩色CCD相机就能捕捉和处理；整个测量系统采用笼式结构，具有高度的灵活性和稳定性；对基于小波变换的相位展开算法进行了编程，实现了被测物体三维位移信息的完整提取。实验证明该测量系统可以实时获取被测物体的三维位移，在测量实验中，获得的三维位移值17.68 μm、36.23 μm、13.85 μm，相比于实际位移值18.1 μm、36.4 μm、14.0 μm它们的绝对误差分别为0.42 μm、0.17 μm、0.15 μm，相对误差分别为2.3%、0.5%、1.1%。     

Doppler optical coherence tomography in cardiovascular applications

The study of flow dynamics in complex geometry vessels is highly important in various biomedical applications where the knowledge of the mechanic interactions between the moving fluid and the housing media plays a key role for the determination of the parameters of interest, including the effect of blood flow on the possible rupture of atherosclerotic plaques. Doppler Optical Coherence Tomography (DOCT), as a functional extension of Optical Coherence Tomography (OCT), is an optic, non-contact, noninvasive technique able to achieve detailed analysis of the flow/vessel interactions. It allows simultaneous high resolution imaging (∼10 μm typical) of the morphology and composition of the vessel and determination of the flow velocity distribution along the measured cross-section. We applied DOCT system to image high-resolution one-dimensional and multi-dimensional velocity distribution profiles of Newtonian and non-Newtonian fluids flowing in vessels with complex geometry, including Y-shaped and T-shaped vessels, vessels with aneurism, bifurcated vessels with deployed stent and scaffolds. The phantoms were built to mimic typical shapes of human blood vessels, enabling preliminary analysis of the interaction between flow dynamics and the (complex) geometry of the vessels and also to map the related velocity profiles at several inlet volume flow rates. Feasibility studies for quantitative observation of the turbulence of flows arising within the complex geometry vessels are discussed. In addition, DOCT technique was also applied for monitoring cerebral mouse blood flow in vivo. Two-dimensional DOCT images of complex flow velocity profiles in blood vessel phantoms and in vivo sub-cranial mouse blood flow velocities distributions are presented.     

Design of multi-spectrum BRDF measurement system

A multi-spectrum bidirectional reflectance distribution function (BRDF) measurement system was developed with the adoption of single reference standard measurement method. An arm-adjustable corner device was designed for the BRDF system. Changing the distance to the sample by moving the detector arm made the device applicable to different wavelengths. The system could be used for the spectrum range from visible light (0.6328 μm) to mid-far infrared (10.6 μm), the facular size between 0.8-3 cm.The rotating limit of detector arm was ±180°, the rotation range of sample holding table was 360°, and the angle resolution was 0.036°. A silicon carbide sample was measured using this system with reflectance zenith from -55° to +55°. According to the error analysis, the measurement uncertainty of this device was about 6.42%.     

Characterization of a 3D MEMS fabricated micro-solenoid at 9.4 T

We present for the first time a complete characterization of a micro-solenoid for high resolution MR imaging of mass- and volume-limited samples based on three-dimensional B(0), B(1) per unit current (B(1)(unit)) and SNR maps. The micro-solenoids are fabricated using a fully micro-electromechanical systems (MEMS) compatible process in conjunction with an automatic wire-bonder. We present 15 μm isotropic resolution 3D B(0) maps performed using the phase difference method. The resulting B(0) variation in the range of [-0.07 ppm to -0.157 ppm] around the coil center, compares favorably with the 0.5 ppm limit accepted for MR microscopy. 3D B(1)(unit) maps of 40 μm isotropic voxel size were acquired according to the extended multi flip angle (ExMFA) method. The results demonstrate that the characterized microcoil provides a high and uniform sensitivity distribution around its center (B(1)(unit) = 3.4 mT/A ± 3.86%) which is in agreement with the corresponding 1D theoretical data computed along the coil axis. The 3D SNR maps reveal a rather uniform signal distribution around the coil center with a mean value of 53.69 ± 19%, in good agreement with the analytical 1D data along coil axis in the axial slice. Finally, we prove the microcoil capabilities for MR microscopy by imaging Eremosphaera viridis cells with 18 μm isotropic resolution.