Moire Fringes Research Articles

Moire fringe measurement method for Young modulus

In this paper, a device is introduced to enlarge micro deformation of steel wire by using Moire fringe formed by double grating, and then measure the Young modulus. Since the angle of the double grating in the device is difficult to control accurately, and it is difficult to accurately achieve the desired magnification, we chose to calculate the magnification by measuring the width of the Moire fringe, and then conducted subsequent measurement. The experimental device proposed in this article has a simple structure and low cost, and can be used as a combination of optical and mechanics experiment content for undergraduate students.

Research on intelligent recognition of Moire fringe effective area

Research on intelligent recognition of Moire fringe effective area

Manipulation of surface plasmon polariton fields excitation at quantum-size slit in a dielectric and graphene interface

The dispersion relation of surface plasmon polaritons is controlled and modified at the interface of atomic and Graphene medium. The beats patterns and moire fringes spacing are modified from vectorial character of the waves and parameters of the driving fields coupled with system energy levels. The beats patterns are investigated with the influence of control fields and its parameters. It is reported that the phase shifts Φ1,2 are the strong functions of the probe detuning and distance x along the interface. The light and surface plasmon polariton waves polarization is a strong oscillation function of both the position and time variation as well as driving fields parameters. The maximum value of phase sensitivity SΦ1 is 600 and SΦ2 is 400 radian per unit change of refractive index of the atomic medium at x=20λ. This work is particularly useful for surface plasmon resonance sensors technology.

Application of Moire Profilometry in Three-Dimensional Profile Reconstruction of Key Parts in Railway.

Moire profilometry (MP) is one of the three-dimensional (3D) topography measurement methods of structured light, which has the advantages of single frame reconstruction, high speed, no contact and high precision, and is suitable for dynamic measurement scenes. In this article, the digital MP is applied to the wheel tread measurement, the virtual grating is generated by computer to project to the object surface, the moire fringe pattern of the object is obtained by filtering, and finally the continuous phase pattern is obtained by phase unwrapping. The 3D shape reconstruction of the wheel tread is realized, and a new method of wheel tread detection is provided. At the same time, in this paper, the results of using different filters are compared, and the significance of the frequency domain filtering to MP is proved. It is necessary to choose a suitable filtering method according to different environmental conditions. At present, digital MP can be used in industrial static detection, and it can be extended to the dynamic detection of rolling wheels in the future, so as to improve the detection efficiency and realize the automatic detection of trains.

The analysis of Influencing Factors of Morie Fringe based on 3D Imaging Simulation and experiment measurement

We propose a three-dimension imaging construction scheme based on Moire fringe and investigate the influencing factors for the fringe generation. Specifically, the principle of the Moire fringe is introduced and a corresponding proof-of-principle experiment is designed and accrued out accompanying with corresponding programming codes subsequently. Four-step phase-shift method and Fourier transform are applied in the experiment to obtain the phase information. Afterwards, the Fourier transformation is added up to a model that shows the surface of the object in terms of the unwrap the phase package. According to the results, the ability of Moire fringe to image is confirmed, which pave a path for various applications, e.g., medical treatment and cryptology.

XRD and TEM analyses of a simulated leached rare earth ore deposit: Implications for clay mineral contents and structural evolution

The types, contents, and microstructures of clay minerals play important roles in controlling the adsorption and desorption of ion-absorbed type rare earth ores and heavy metals. By selecting a typical rare earth ore profile, we conducted a leaching experiment and used XRD (X-ray diffraction) and TEM (Transmission electron microscopy) analyses to determine the clay mineral types and microstructural changes after various leaching periods. The XRD phase analyses showed that the main minerals in the simulated rare earth ore were quartz, potassium feldspar, kaolinite, and illite. TEM images showed that the mineral aggregates were broken, disintegrated, and transformed by the leaching process, and a large number of moire fringes were visible. With continuous leaching, REEs (Rare Earth Elements) were gradually re-solved and leached. The results of the leaching experiment indicate that fine-grained minerals in rare earth ores, such as potassium feldspar and clay minerals, migrated downward with the leaching solution. Leaching also promoted the alteration of potassium feldspar to clay minerals, as well as mutual alteration of clay minerals. Under acidic or neutral conditions during the early stage, potassium feldspar was altered to kaolinite or illite, whereas during the middle and late stages of leaching it was altered as follows: illite → mixed-layer illite–kaolinite → kaolinite → mixed-layer kaolinite–illite → illite. This transformation has an important effect on the release of REEs and heavy metals and provides insights into improving the leaching process and explaining heavy metal pollution in rare earth mining areas.

Study on High Precision Fabric Density Measuring Instrument and Measuring Method Based on Moire Fringe

With the continuous development of science and the continuous progress and reform of fabric knitting technology, all kinds of fabrics continue to appear. Linear density is one of the most important physical and geometric characteristics of knitted fabrics, which affects the physical and mechanical properties, feel and style of textiles, and is one of the important bases for fabric design and manufacturing process parameters.In this paper, a device and method is developed, which is not affected by the width and density of fabric lines, and can accurately measure the density of fabric. The invention puts forward a method of measuring fabric density from a new point of view. Using the phenomenon of moire fringes, the fabric density of the fabric to be measured is calculated by measuring the angle. The device has the advantages of simple structure, low production cost, and is not affected by the width and density of cloth lines. it can measure fabrics with high line density or wide lines, and has the advantages of high precision and convenient operation. and the gratings with different grating constants can be selected according to the characteristics of the fabric, which has a very wide range of application.

Utilization of 3-T fetal magnetic resonance imaging in clinical practice: a single-institution experience.

As the safety and efficacy of fetal magnetic resonance imaging (MRI) at 3 tesla (T) continues to evolve, understanding its potential benefits and limitations is becoming increasingly important. We aim to compare the image quality of fetal MRI between 1.5T and 3T in routine clinical practice. Fetal MRIs performed at 3T between Jan. 1, 2019, and Dec. 31, 2019, at our institution were retrospectively reviewed by four fellowship-trained subspecialty radiologists. Imaging quality by system, sequence and artifacts were compared with matched controls at 1.5T and rated using a modified Likert scale. Thirty-three fetal MRIs at 3T were reviewed, and a control group of studies for the same clinical indication and equivalent gestational age were selected for comparison. Two of the four radiologists preferred 3-T image quality of the brain with slight agreement among the four reviewers (k=0.19, P=0.01). Three of the four radiologists had no preference for 1.5T vs. 3T in the majority of cases in evaluating the chest and abdomen. In the overall assessment, 3T was preferred in less than half of cases by all four radiologists (k=0.07, P=0.26). In the evaluation of standing wave, moire fringe and magnetic susceptibility artifacts, 3T was not preferred in the majority of studies by all four radiologists. Total exam time was significantly longer in the 3-T fetal MRIs (75.0±15.1min) compared to the 1.5-T fetal MRIs (55.5±13.3min, P<0.001). While 3T is a feasible alternative to 1.5T for fetal MRI, the increased artifacts and longer exam times observed at 3T without clear improvement in overall image quality make 1.5T preferable for fetal MRI in routine clinical practice.

Fringe Pattern Denoising Using Two-Dimensional Variational Mode Decomposition (2D-VMD) Method for Inspection of Flatness of Reduced Surfaces

The flatness is a major element for any functional precision surface. It becomes extremely important in the miniaturization of the systems, which require the components of reduced sizes. There is a need to develop appropriate methods to solve measurement problems in industrial design, manufacturing of production and process monitoring. In this work, we used an optical method based on the moire interferometry for topography in full-field and to control the flatness of the reduced surfaces having a size of 30 mm2 and more. This technique makes it possible to palpate optically the surface and to give an instantaneous topography of surface in real-time. We have developed an optical set-up which it is possible to inspect in a nondestructive way and without contact, the surface quality. Unfortunately, the moire fringes taken by camera contain excessive noise. That is why we proposed to use the Two-Dimensional Variational Mode Decomposition (2D-VMD) method to reduce the random noise from the fringe patterns and to ameliorate the profiles and the residual images from which we can control the presence of defects flatness of reduced surfaces. We have also used three objective image quality evaluation methods (PSNR, SNR and correlation coefficient) to compare between the denoising results given by 2D-VMD with those obtained by the Bidimensional Empirical Mode Decomposition (BEMD).

Analysis and Comparison of Three Classical Color Image Interpolation Algorithms

With the development of society, the progress of science and technology, the level of computer has been improved. Digital imaging technology has also achieved unprecedented development. The most commonly used digital cameras are Charge-coupled device (CCD) and Complementary Metal Oxide Semiconductor (CMOS) image sensors. Bayer filters are often used to help sensors capture color information. However, only one component can be achieved per pixel. Full-color images must be obtained by color interpolation. Therefore, the color interpolation algorithm has attracted the attention of the academic community. In this paper, three classical color interpolation algorithms- Bilinear interpolation algorithm, COK Algorithm, Gradient Interpolation Algorithm- are compared and studied. The Optimal Algorithm is selected by comparing false color, noise and color moire fringe. After comparison, it is found that the three basic algorithms will have color moire fringes appear. But the gradient interpolation algorithm has the least moire fringe and noise. COK Algorithm, second of all. But the COK Algorithm has color overflows.

Dynamic out-of-plane displacement measurement using the instantaneous analysis phase-shifting method

This paper presents an instantaneous analysis shadow moire method for dynamic out-of-plane displacement measurement. The shadow moire method is widely applied to the measurement of the out-of-plane displacement, such as the deformation or warpage on the surface of the objects. Generally, the method of phase shifting is used to analyze the phases of the shadow moire fringes and to obtain the out-of-plane displacement. To generate accurate phase shifting, the grating must be moved step by step precisely. However, the step motion provided by the conventional mechanical device is neither accurate nor prompt. In this study, a novel stair-structured plate consisting of a series of 4-step-height sets is designed to produce shadow moire fringes with the quadrature phase. The quadrature-phase fringes are utilized to extract instantaneously the shadow moire phase for measurement of the dynamic out-of-plane displacement of an object. Experiments show that our method can effectively detect the dynamic out-of-plane displacement with a micrometric scale resolution and is capable of suppressing the discrepancy of displacement to 0.83 $$\%$$ . The proposed measurement method of the out-plane displacement is suitable for the pressure sensing or application of the tactile sensor.

Implementation of Talbot–Lau x-ray deflectometry in the pulsed power environment using a copper X-pinch backlighter

A Talbot–Lau x-ray deflectometer can map electron density gradients in high energy density plasmas, as well as provide information about plasma elemental composition through single-image x-ray refraction and attenuation measurements. A new adaptation to a pulsed power environment used backlighting from copper X-pinches, allowing for electron density mapping of a low-Z object. Even though the X-pinch backlighter is not properly optimized for emitting x-rays in terms of source size and photon fluence, Moire fringe patterns with contrast up to 14% and fringe shift due to refraction on a beryllium object are obtained. Due to the proximity of the deflectometer with the X-pinch (∼6 cm), it is shown that a protective filter is required to avoid damage in the closest (i.e., source) grating due to both plasma debris and mechanical shock. Regarding grating survival, these did not show any damage due to the intense magnetic field or heating induced by plasma radiation. Electron density on beryllium was measured with a difference lower than 16%. The areal electron density mapping of the sample was limited by source size characteristics, in similarity to transmission radiography. These results show the potential of plasma electron density as well as material mapping through Talbot–Lau x-ray deflectometry in a pulsed power environment.

Fourier transform phase retrieval for x-ray phase-contrast imaging based on cascaded Talbot–Lau interferometers

Long exposure time is one of the major limitations in x-ray phase-contrast imaging (XPCI). Therefore, we demonstrate a promising alternative method for grating-based XPCI coupled with cascaded Talbot–Lau interferometers (TLIs). A Fourier analysis of the moire fringe patterns generated by the interferometers was used to obtain the multicontrast images (such as absorption, differential phase-contrast, and normalized visibility-contrast images) with a single exposure. The cascaded configuration with TLI and inverse TLI using large-period absorption gratings was established to verify the effectiveness of the algorithm and three multicontrast images of a polytetrafluoroethylene (PTFE) tube were obtained experimentally. The groove structures in the PTFE can be clearly identified in the differential phase-contrast image. This method shows potential for application of cascaded TLI in medical imaging.

High-resolution imaging of organic pharmaceutical crystals by transmission electron microscopy and scanning moiré fringes.

SummaryFormulation processing of organic crystalline compounds can have a significant effect on drug properties, such as dissolution rate or tablet strength/hardness. Transmission electron microscopy (TEM) has the potential to resolve the atomic lattice of these crystalline compounds and, for example, identify the defect density on a particular crystal face, provided that the sensitivity of these crystals to irradiation by high‐energy electrons can be overcome. Here, we acquire high‐resolution (HR) lattice images of the compound furosemide using two different methods: low‐dose HRTEM and bright‐field (BF) scanning TEM (STEM) scanning moiré fringes (SMFs). Before acquiring HRTEM images of furosemide, a model system of crocidolite (asbestos) was used to determine the electron flux/fluence limits of low‐dose HR imaging for our scintillator‐based, complementary metal‐oxide semiconductor (CMOS) electron camera by testing a variety of electron flux and total electron fluence regimes. An electron flux of 10 e−/(Å2 s) and total fluence of 10 e−/Å2 was shown to provide sufficient contrast and signal‐to‐noise ratio to resolve 0.30 nm lattice spacings in crocidolite at 300 kV. These parameters were then used to image furosemide which has a critical electron fluence for damage of ≥10 e−/Å2 at 300 kV. The resulting HRTEM image of a furosemide crystal shows only a small portion of the total crystal exhibiting lattice fringes, likely due to irradiation damage during acquisition close to the compound's critical fluence. BF‐STEM SMF images of furosemide were acquired at a lower electron fluence (1.8 e−/Å2), while still indirectly resolving HR details of the (001) lattice. Several different SMFs were observed with minor variations in the size and angle, suggesting strain due to defects within the crystal. Overall BF‐STEM SMFs appear to be more useful than BF‐STEM or HRTEM (with a CMOS camera) for imaging the crystal lattice of very beam‐sensitive materials since a lower electron fluence is required to reveal the lattice. BF‐STEM SMFs may thus prove useful in improving the understanding of crystallization pathways in organic compounds, degradation in pharmaceutical formulations and the effect of defects on the dissolution rate of different crystal faces. Further work is, however, required to quantitatively determine properties such as the defect density or the amount of relative strain from a BF‐STEM SMF image.

3-DOF measurement method for non-diffracting Moiré fringes based on CGH

Aiming at the motion errors of the linear stage, a measurement method for the determination of three-degree-of-freedom (3-DOF) error motions is proposed based on non-diffracting Moire fringes produced by computer-generated holograms (CGHs). A liquid crystal spatial light modulator (SLM) is used to generate non-diffracting beams, and two non-diffracting beams form Moire fringes. A 3-DOF measuring optical path of non-diffracting Moire fringes is designed. Meanwhile, a 3-DOF mathematical model of motion errors is established, and three kinds of motion errors (yaw angle, roll angle and pitch angle) are separated by geometric analysis method. A rotary table is used to simulate the 3-DOF motion errors on different conditions. The NDB and non-diffracting Moire fringe patterns are obtained by CCD1 and CCD2 respectively. Experimental results show that the motion errors calculated by the positions of the central points agree well with the theoretical value with the error less than 0.0104°, which can verify the feasibility and correctness of the 3-DOF measurement system for non-diffracting Moire fringes.

Design of a Roll Angle Measuring Sensor

Aiming at the measurement of roll deformation between two devices, we propose a novel scheme and elaborate the structure design in this paper. The scheme can realize the relative measurement of roll angle even if the system does not provide a reference datum, which effectively solves the problems of limited measurement range of moire fringes and accuracy guarantee only in an extremely small angle range. First, the principle of measuring the roll angle by moire fringes is introduced, and the effects of various error sources in the system are comprehensively considered. Then, the combined measurement scheme and the entire system composition structure are analyzed in detail. In addition, an experimental setup is designed to verify the accuracy of roll deformation measurement. The measurement results show that the root mean square (RMS) error can reach $6.9^{\prime \prime }$ within 3°, and is less than $7.8^{\prime \prime }$ in the range of 0°-90°. Hence, our proposed scheme has a good measurement stability in a large roll range.

Measurement method of axicon cone angle based on moire fringes of non-diffracting beam

为了准确地测量轴锥透镜锥角值，根据无衍射光同心圆环间距不随距离改变的特点和莫尔条纹放大的特性，提出了一种基于无衍射光莫尔条纹的轴锥透镜锥角的测量方法。当无衍射光束经分束器分光合束后形成莫尔条纹，平移其中一束光在图像传感器上的位置，实现莫尔条纹数量的变化，通过记录不同莫尔条纹下的中心距离计算出轴锥透镜锥角。实验以锥角为0.5°的轴锥透镜作为被测对象，与CMM测量结果进行比较，该文提出的方法相对测量误差近似为0.54%，重复性为0.86″，验证了该文方法测量轴锥透镜锥角的可行性。

Color modulation by selective excitation activated defects and complex cation distribution in Zn1-xMgxAl2O4 nanocrystals.

Complex cation distribution in spinel solid solution, fosters defect generation and permutates the optical properties. To scrutinize the effect on structural properties, viz. the cation distribution and defect states upon substitution of Zn with Mg; and to tune the emission properties, Zn1-xMgxAl2O4 (0.01 ≤ x ≤ 0.30) nanocrystals are synthesized. The nanocrystals show increased inversion and generation of multiple defects, namely zinc vacancies, zinc interstitials, oxygen vacancies and antisite defects with increasing Mg content, which thereby impacts the optical band gap. Pentahedral coordination in addition to tetra- and octahedral coordination of Al has been observed, which infers the presence of oxygen vacancies and dangling bonds. Moire fringes formation has intimated the presence of two or more crystal lattices with higher Mg substitution. Band-to-band and defect-assisted photoluminescence shows the role of multiple defects, especially defect clusters, in deciphering the properties of the resulting crystals. Color change from bluish-white to pink has been achieved depending upon the excitation wavelength and emission mechanism, as proposed through a band model schematic. The presented study may be beneficial for designing the Zn1-xMgxAl2O4 nanocrystals with optimized emission properties.

Synthesis of CdS/CdSe Core/Shell Heterostructures Using Ultrasonic Assisted Sol–Gel Method

Inverted type CdS/CdSe core/shell heterostructures were synthesized using ultrasonic assisted low cost and environmentally friendly sol–gel route. Cadmium chloride, thiourea and selenium dioxide were used as Cd, S and Se precursors, respectively. The core/shell heterostructures were analyzed by various techniques like X-ray diffraction, high resolution transmission electron microscope (HRTEM), photoluminescence and optical studies. X-ray diffractograms exhibit the cubic phase structure with its peaks shifting towards the lower angle due to compressive strain. Moire fringes are observed in HRTEM images of CdS/CdSe core/shell heterostructure due to lattice mismatch between CdS and CdSe. The interplanar spacing of moire fringes is found to be around 2.38 nm. Photoluminescence studies show the peak shifts towards the higher wavelength due to lattice mismatch between CdS and CdSe. Shift in absorption peak towards the higher wavelength makes them suitable for dye synthesized solar cells.

2D/3D mixed display based on integral imaging and a switchable diffuser element.

In this paper, we present a 2D/3D mixed system with high image quality based on integral imaging and a switchable diffuser element. The proposed system comprises a liquid crystal display screen, lens array, switchable diffuser element and projector. The switchable diffuser element can be controlled to present 2D/3D mixed images or 2D and 3D images independently, and can reduce the Moire fringe and black grid. In addition to the improved display quality, the proposed system has advantages of a simple structure and is low cost, which contribute to the portability and practicability.