用预抽气真空腔法测量及补偿空气折射率的研究

空气折射率的补偿效果在高精度激光干涉测量中起着“瓶颈”作用。分析了空气折射率的补偿原理,回顾了几种空气折射率的测量方法及特点。在此基础上,深入研究了用预抽气真空腔测量与补偿空气折射率的测量原理、方法和装置。该方法保持了干涉法测量空气折射率能充分反映所有导致折射率变化的环境因素的特点,避免了测量过程中由于抽气过程给测量带来的干扰。通过空气折射率测量及补偿实验,证实了该方法的可行性,测量结果经补偿后可使精度提高一个数量级。     

Measuring opto‐thermal parameters of basalt fibers using digital holographic microscopy

A method for studying the effect of temperature on the optical properties of basalt fiber is presented. It is based on recording a set of phase‐shifted digital holograms for the sample under the test. The holograms are obtained utilizing a system based on Mach–Zehnder interferometer, where the fiber sample inserted in an immersion liquid is placed within a temperature controlled chamber. From the recorded digital holograms the optical path differences which are used to calculate the refractive indices are determined. The accuracy in the measurement of refractive indices is in the range of 4 × 10^?4. The influence of temperature on the dispersion parameters, polarizability per unit volume and dielectric susceptibility are also obtained. Moreover, the values of dispersion and oscillation energies and Cauchy's constants are provided at different temperatures.     

Images of absolute retardance L.Δn, using the rotating polariser method

Modulation techniques for measuring changes in optical birefringence, such as the rotating-polariser method (Wood & Glazer, 1980, J. Appl. Crystallogr . 13, 217), allow one to determine |sin δ|, δ = 2π L Δ n /λ, Δ n = double refraction, L  = light path and λ = wavelength. However, they generally suffer from not providing absolute values of the optical retardance or are limited to relatively low retardance values. In addition, knowledge of the absolute phase is required when establishing the correct values of optical orientation information. In this paper, it is shown how the phase δ, and thus optical retardance, can be extracted from combining measurements of |sin δ| at different wavelengths. The new approach works on each single point of a 2-D picture without the need to correlate with neighbouring points. There is virtually no limit to the retardance, and the computational efforts are small compared with other methods (e.g. Ajovalasit et al. 1998, J. Strain Analysis 33 , 75). When used with imaging techniques, such as the rotating polariser method of Glazer, Lewis & Kaminsky 1996 ( Proc. R. Soc. London Series A452 , 2751) this process has the potential to identify automatically optically anisotropic substances under the microscope. The algorithm derived in this paper is valid not only for birefringence studies, but can be applied to all studies of interfering light waves.     

A novel dynamic opto‐thermo‐mechanical stress testing device 1: Design of the device

This article presents a dynamic opto‐thermo‐mechanical stress testing device to characterize fiber properties. The device has multi‐modes and consists of many functions. These modes include stretching, bending, rotating, twisting, and heating processes. Every process can be controlled by micro‐controller unit via software programs specially designed for this purpose. The micro‐controller unit can execute two different processes at the same time. Such as, dynamic stretching process under the effect of thermal treatment, dynamic stretching process and relaxation, bending process under the effect of thermal treatment, and so forth. Software programs with their flow charts are designed for the application of these processes. The advantage of this device is that it can be done statically and dynamically to characterize all types of fibers (polymer and optical). The device is designed to be attached with two‐beam polarizing interference microscope to investigate the dynamic opto‐thermo‐mechanical properties of the tested fiber under the effect of different applied stresses. Isotactic polypropylene, iPP, fiber is used for some applications of this device, as examples, in stretching, rotation, and twisting modes. Interferograms and graphs are given for illustration.     

一种溶液浓度分布测量方法简介

提出了一种在纹影法的基础上加以改进后能够对溶液的浓度轮廓进行观察与测量的新的显微成像测量方法——暗场纹影法。同时给出了该方法原理性实验的观察结果 ,并与微分干涉显微镜的观察结果进行了对比     

Three‐dimensional analysis of injury conditions of single muscle fibers in small animals using phase‐contrast X‐ray imaging

Muscle damage can reduces the biological functions and lead to ultimately a disease state. For the reason, it is important to accurately check the state of an injury such as atrophy, and it is required to identify the state of fibers constituting the muscle. This study describes a novel method of analyzing single muscle fibers with injury conditions in three‐dimensions. The muscle fibers of the mice were visualized using phase‐contrast X‐ray projection the microstructure. In additions, it was possible to confirm the status by quantitatively analyzing the injury severity of muscle fibers. Significantly, the muscle conditions of multiple individuals were individually determined. This study could contributes to areas where it is very important to identify microdetailed and quantitative changes of state, such as new drug development.     

一种精确测量微量液体折射率的新方法

摘 要：本文介绍了一种用玻璃毛细管精确测量微量液体折射率的新方法。这种方法基于共轴球面光学系统的成像原理,通过读数显微镜对吸入待测液体后毛细管的焦点位置进行单一参数的测量,进而计算出待测液体的折射率。用此方法测量了纯水、乙醇、乙二醇、丙三醇的折射率,各种待测样品的需要量小于0.002 ml;对纯水和乙醇样品,折射率测量精度优于0.0003;对乙二醇和丙三醇样品,折射率测量精度优于0.0007。选用适当的毛细管参数,可以进一步提高这种测量方法的测量精度,扩展折射率的测量范围。该方法具有待测液体用量极少、使用的设备简单、操作方便和折射率测量精度高的特点。论文对实验测量误差以及进一步提高测量精度作了详细的分析和讨论。     

A microinterferometric method for analysis of rotation-symmetric refractive-index gradients in intact objects

A new method for measuring refractive-index gradients in rotation-symmetric objects is described. Interference micrographs of intact objects, with the symmetry axis perpendicular to the optical axis of the microscope, are used to obtain a phase-shift profile, which is converted into a refractive-index profile by a computer program. The conversion calculations are based on iterative approximations of the gradient slope in a number of presumed shells in the object. The method is fast, convenient and yields highly accurate results even when only a small number of phase shift values can be obtained. The new method is especially advantageous for analysing many invertebrate eyes but it can also be used for measuring manufactured graded-index optical fibres.     

Advantages and pitfalls of using free‐hand sections of frozen needles for three‐dimensional analysis of mesophyll by stereology and confocal microscopy

The anatomical structure of mesophyll tissue in the leaf is tightly connected with many physiological processes in plants. One of the most important mesophyll parameters related to photosynthesis is the internal leaf surface area, i.e. the surface area of mesophyll cell walls exposed to intercellular spaces. An efficient design‐based stereological method can be applied for estimation of this parameter, using software‐randomized virtual fakir test probes in stacks of optical sections acquired by a confocal microscope within thick physical free‐hand sections (i.e. acquired using a hand microtome), as we have shown in the case of fresh Norway spruce needles recently. However, for wider practical use in plant ecophysiology, a suitable form of sample storage and other possible technical constraints of this methodology need to be checked. We tested the effect of freezing conifer needles on their anatomical structure as well as the effect of possible deformations due to the cutting of unembedded material by a hand microtome, which can result in distortions of cutting surfaces. In the present study we found a higher proportion of intercellular spaces in mesophyll in regions near to the surface of a physical section, which means that the measurements should be restricted only to the middle region of the optical section series. On the other hand, the proportion of intercellular spaces in mesophyll as well as the internal needle surface density in mesophyll did not show significant difference between fresh and frozen needles; therefore, we conclude that freezing represents a suitable form of storage of sampled material for proposed stereological evaluation.     

A modified method for accurate correlation between the craze density and the optomechanical properties of fibers using pluta microscope

A modified method was suggested to improve the performance of the Pluta microscope in its nonduplicated mode in the calculation of the areal craze density especially, for relatively low draw ratio (low areal craze density). This method decreases the error that is resulted from the similarity between the formed crazes and the dark fringes of the interference pattern. Furthermore, an accurate method to calculate the birefringence and the orientation function of the drawn fibers via nonduplicated Pluta polarizing interference microscope for high areal craze density (high draw ratio) was suggested. The advantage of the suggested method is to relate the optomechanical properties of the tested fiber with the areal craze density, for the same region of the fiber material. Microsc. Res. Tech. 79:422–430, 2016. © 2016 Wiley Periodicals, Inc.     

Three-dimensional morphometry in scanning electron microscopy: a technique for accurate dimensional and angular measurements of microstructures using stereopaired digitized images and digital image analysis

A method for accurate dimensional and angular measurements of microstructures analysed in the scanning electron microscope is described. The method considers central and parallel projections and involves (a) digital image acquisition of stereopaired images from the scanning electron microscope's photodisplay, (b) generation of 3D-image representations, (c) setting of measuring points in the digitized stereopaired images, (d) computation of exact space coordinates ( x / y / z ) from the corresponding point coordinates ( x _L/ y _L; x _R/ y _R), (e) determination of distances and angles between consecutive corresponding points using vector equations, and (f) transfer of computed data into spreadsheets of the data analysis software using dynamic data exchange with simultaneous graphical display of the frequency distribution of variables.
Measurements performed on specimens with known dimensions (grid with 10 μm wide square meshes, polystyrene beads with 0.33 μm diameter) and angles (synthetic crystals of K(Al,Cr)[SO₄], CuSO₄.5H₂O and NaCl) revealed a high accuracy in dimensional as well as angular measurements (total error 1 ± 0.5%).
In Monte Carlo experiments the overall error was found to depend strongly on the size of the measured structure relative to the size of the measurement field (field width).     

A method for structure analysis of nanomaterials by electron diffraction: Phase identification and unit cell determination

We report a quick and easy method for a random selected area electron diffraction (SAED) pattern without rotating and tilting the specimen to perform phase identification and unit cell determination by combined with the XRD softwares. If your TEM is well aligned and camera length is carefully corrected, two‐dimensional (2D)‐SAED pattern can be directly transformed to 1D‐profile after the center determination of pattern, this profile is then imported to XRD analysis packages. Finally, phase identification and unit cell determination can be performed after peak search or precise peak position determined by profile fitting. Two examples, flaky‐like TiO₂ nanomaterial and TiO₂ nanotubes precipitated by the silver nanoparticles, were tested and verified for the validation of phase identification and unit cell determination using this method; the successful crystallographic analysis of one single gold nanocrystal indicates it is still validate for the nanocrystals with the smaller diffraction volume, but need two or more random tilt SAED patterns. This method could be further used in the quantitative phase analysis, structure determination and Rietveld refinement for the nanomaterials if the reliable integrated intensity can be extracted. Microsc. Res. Tech. 76:641–647, 2013. © 2013 Wiley Periodicals, Inc.     

Rapid in‐focus corrections on quantitative amplitude and phase imaging using transport of intensity equation method

Transport of intensity equation (TIE) method can acquire sample phase distributions with high speed and accuracy, offering another perspective for cellular observations and measurements. However, caused by incorrect focal plane determination, blurs and halos are induced, decreasing resolution and accuracy in both retrieved amplitude and phase information. In order to obtain high‐accurate sample details, we propose TIE based in‐focus correction technique for quantitative amplitude and phase imaging, which can locate focal plane and then retrieve both in‐focus intensity and phase distributions combining with numerical wavefront extraction and propagation as well as physical image recorder translation. Certified by both numerical simulations and practical measurements, it is believed the proposed method not only captures high‐accurate in‐focus sample information, but also provides a potential way for fast autofocusing in microscopic system.     

A new method for the accurate measurement of higher-order frequency response functions of nonlinear structural systems

Higher-order frequency response functions (FRFs) are important to the analysis and identification of structural nonlinearities. Though much research effort has been devoted recently to their potential applications, practical issues concerning the difficulty and accuracy of higher-order FRF measurement have not been rigorously assessed to date. This paper presents a new method for the accurate measurement of higher-order FRFs. The method is developed based on sinusoidal input, which is ideal for exciting a nonlinear structure into desired regimes with flexible control, and the correlation technique, which is a novel signal processing method capable of extracting accurate frequency components present in general nonlinear responses. The correlation technique adopted is a major improvement over Fourier transform based existing methods since it eliminates leakage and aliasing errors altogether and proves to be extremely robust in the presence of measurement noise. Extensive numerical case studies have been carried out to critically assess the capability and accuracy of the proposed method and the results achieved are indeed very promising. Interesting nonlinear behavior such as frequency shift and jump have been observed in first-, second- and third-order FRFs, as well as solitary islands which have been identified over which higher-order FRFs virtually do not change as input force amplitude varies. Higher-order FRFs over such solitary islands are essentially their theoretical counterparts of Volterra transfer functions which can be measured with very low input force and can be profitably employed for the identification of physical parameters of structural nonlinearities. Subsequently, a nonlinear parameter identification method has also been developed using measured higher-order FRFs and results are presented and discussed.     

Application of micro‐CT: A new method for stone drilling research

Drilling is one of the most complex techniques for making ancient stone implement or adornment. For smaller perforations, it is very difficult to effectively observe drilling marks under microscope, SEM, or to obtain negative silicone rubber cast. In this report, a new exclusive nondestructive method was first introduced to resolve the observation difficulty. Virtual 3D reconstruction by using micro CT (μCT) was successfully applied to disclose drilling tool marks on the inner wall of one small perforation and its relative drilling technique was deduced, which implied that μCT has great potential to understand ancient stone drilling. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.     

A tracking‐based nanoimaging method for fast detection of surfaces' inhomogeneities using gold nanoparticles

The localization of surfaces inhomogeneities is central to many areas of technology, chemistry and biology, ranging from surface defects in industry to the identification and screening of early bio‐defects inside cells. The development of methods that enable direct, sensitive, and rapid detection of those inhomogeneities is both relevant and timely. To address this challenge, we developed a far‐field nanoimaging method to detect the presence of surface's nanodefects that modify the signal emitted by gold nanoparticles (AuNPs) under laser irradiation. Our technique is based on the formation of hot spots due to the confinement of light in the proximity of the AuNP, whose positions depend on the polarization direction of the incident beam. An inhomogeneity is detected as an increase in the intensity collected from the hot spots when a laser beam is orbiting the nanoparticle and the incident polarization direction of the laser beam is changed periodically.     

Application of autofluorescence robotic histology for quantitative evaluation of the 3‐dimensional morphology of murine articular cartilage

Murine models of osteoarthritis (OA) are increasingly important for understating pathogenesis and for testing new therapeutic approaches. Their translational potential is, however, limited by the reduced size of mouse limbs which requires a much higher resolution to evaluate their articular cartilage compared to clinical imaging tools. In experimental models, this tissue has been predominantly assessed by time‐consuming histopathology using standardized semi‐quantitative scoring systems. This study aimed to develop a novel imaging method for 3‐dimensional (3D) histology of mouse articular cartilage, using a robotic system—termed here “3D histocutter”—which automatically sections tissue samples and serially acquires fluorescence microscopy images of each section. Tibiae dissected from C57Bl/6 mice, either naïve or OA‐induced by surgical destabilization of the medial meniscus (DMM), were imaged using the 3D histocutter by exploiting tissue autofluorescence. Accuracy of 3D imaging was validated by ex vivo contrast‐enhanced micro‐CT and sensitivity to lesion detection compared with conventional histology. Reconstructions of tibiae obtained from 3D histocutter serial sections showed an excellent agreement with contrast‐enhanced micro‐CT reconstructions. Furthermore, osteoarthritic features, including articular cartilage loss and osteophytes, were also visualized. An in‐house developed software allowed to automatically evaluate articular cartilage morphology, eliminating the subjectivity associated to semi‐quantitative scoring and considerably increasing analysis throughput. The novelty of this methodology is, not only the increased throughput in imaging and evaluating mouse articular cartilage morphology starting from conventionally embedded samples, but also the ability to add the third dimension to conventional histomorphometry which might be useful to improve disease assessment in the model.