Showing papers on "Moiré pattern published in 2013"

Scanning moiré fringe imaging for quantitative strain mapping in semiconductor devices

Abstract: The development of a method for the precise measurement of strain fields in semiconductor devices has become a critical requirement because the electrical performances of the devices are greatly influenced by the strain induced in their structures. We applied scanning moire fringe imaging to demonstrate the quantitative strain mapping of a Si/Si1−xGex interfacial layer. The strain field was measured at a nano-meter scale spatial resolution, with a detection precision of 0.1%. The maximum value of the strain was measured to be 1.1% ± 0.1%, which is consistent with the direct measurement by high-resolution scanning transmission electron microscopy image.

Radiographic phase-contrast imaging apparatus

Abstract: A radiographic phase-contrast imaging apparatus obtains a phase-contrast image using two gratings including the first grating and the second grating. The first and second gratings are adapted to form a moire pattern when a periodic pattern image formed by the first grating is superimposed on the second grating. Based on the moire pattern detected by the radiographic image detector, image signals of the fringe images, which correspond to pixel groups located at different positions with respect to a predetermined direction, are obtained by obtaining image signals of pixels of each pixel group, which includes pixels arranged at predetermined intervals in the predetermined direction, as the image signal of each fringe image, where the predetermined direction is a direction parallel to or intersecting a period direction of the moire pattern other than a direction orthogonal to the period direction. Then, a phase-contrast image is generated based on the obtained fringe images.

Tilted elemental image array generation method for moiré-reduced computer generated integral imaging display

Abstract: In this paper, we propose a tilted elemental image array generation method for computer generated integral imaging display with reduced moire patterns. The pixels of the tilted elemental image array are divided into border pixels and effective pixels. According to the optimal tilted angle, the effective pixels are arranged with uniform arrangement. Also, a pixel mapping method is proposed. Appropriate experiments are carried out and the experimental results show that not only the color moire patterns are reduced remarkably, but also the resolution of the reconstructed 3D images are improved through the proposed method.

Four-quadrant gratings moiré fringe alignment measurement in proximity lithography

Abstract: This paper aims to deal with a four-quadrant gratings alignment method benefiting from phase demodulation for proximity lithography, which combines the advantages of interferometry with image processing. Both the mask alignment mark and the wafer alignment mark consist of four sets of gratings, which bring the convenience and simplification of realization for coarse alignment and fine alignment. Four sets of moire fringes created by superposing the mask alignment mark and the wafer alignment mark are highly sensitive to the misalignment between them. And the misalignment can be easily determined through demodulating the phase of moire fringe without any external reference. Especially, the period and phase distribution of moire fringes are unaffected by the gap between the mask and the wafer, not excepting the wavelength of alignment illumination. Disturbance from the illumination can also be negligible, which enhances the technological adaptability. The experimental results bear out the feasibility and rationality of our designed approach.

Conductive film, display device incorporating the same, and conductive film pattern determination method

Abstract: PROBLEM TO BE SOLVED: To provide a conductive film which can restrain the occurrence of moire and can greatly improve visibility, and a method for determining a conductive film pattern.SOLUTION: A wiring pattern is the one to which are imparted irregularities in a designated range conforming to the rhombic shape of a rhombic wiring pattern where, with respect to moire frequencies and intensities derived by exerting effects of visual response characteristics of human beings upon moire frequency information and intensity information calculated from the peak frequency and peak intensity of a two-dimensional Fourier spectrum of the permeability image data of the wiring pattern and of the permeability image data of a pixel arrangement pattern, respectively, the sum of the moire intensities at which the moire frequencies fall within a designated frequency range determined according to the visual response characteristics is equal to or less than a designated value.

Shadow moiré technology based fast method for the measurement of surface topography

Abstract: We present a fast phase-shifting shadow moire device for surface topography measurement. In our setup, multiple light sources located at different positions are controlled to illuminate the grating sequentially. Therefore, the phase shift across the field of view shadow moire is introduced by changing the distance between the light source and the camera. Thanks to the necessity for mechanical movement being omitted here, the proposed setup can capture the phase-shifting fringe patterns at a high speed. However, affected by the bias modulation and amplitude modulation of the captured fringe patterns, the phase of interest cannot be demodulated by the standard phase-shifting algorithm directly. Thus the principal component analysis (PCA) demodulation approach is used to extract the wrapped phase map. In addition, we develop an iterative procedure to reduce the detuning error introduced by the PCA algorithm. The proposed method implements a fast way to determine the topography of a surface through a simple experimental setup. It is applied to obtain an external surface of a specimen. Both the simulation results and the experimental results show the validity of the proposed technique.

Target-Driven Moire Pattern Synthesis by Phase Modulation

Abstract: This paper investigates an approach for generating two grating images so that the moire pattern of their superposition resembles the target image. Our method is grounded on the fundamental moire theorem. By focusing on the visually most dominant (1,-1)-moire component, we obtain the phase modulation constraint on the phase shifts between the two grating images. For improving visual appearance of the grating images and hiding capability the embedded image, a smoothness term is added to spread information between the two grating images and an appearance phase function is used to add irregular structures into grating images. The grating images can be printed on transparencies and the hidden image decoding can be performed optically by overlaying them together. The proposed method enables the creation of moire art and allows visual decoding without computers.

Strain Analysis of Semiconductor Device by Moiré Fringes in STEM Image

Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

At-wavelength metrology using the moiré fringe analysis method based on a two dimensional grating interferometer

Abstract: A two-dimensional (2D) grating interferometer was used to perform at-wavelength metrology. A Fast Fourier Transform (FFT) of the interferograms recovers the differential X-ray beam phase in two orthogonal directions simultaneously. As an example, the X-ray wavefronts downstream from a Fresnel Zone plate were measured using the moire fringe analysis method, which requires only a single image. The rotating shearing interferometer technique for moire fringe analysis was extended from one dimension to two dimensions to carry out absolute wavefront metrology. In addition, the 2D moire fringes were extrapolated using Gerchberg's method to reduce the boundary artifacts. The advantages and limitations of the phase-stepping method and the moire fringe analysis method are also discussed.

Dynamic deformation measurement of real bridge using sampling moire camera

Abstract: Sampling moire method is one of the convenient phase analysis methods. The accuracy of phase difference analysis is from 1/100 to 1/1000 of the grating pitches. This method is useful to a real-time measurement because the phase analysis can be performed from a single-shot image. In this paper, we developed a sampling moire camera which can analyze grating phase in real-time. This camera can measure dynamic deformation of a structure in real-time. Applications for dynamic deformation measurement of a real bridge are demonstrated.

Moiré Fringe Phase Difference Measurement Based on Spectrum Zoom Technology

Abstract: Grating displacement measurement technique is an important means to achieve precise displacement measurement of nanometer scale. Moire fringe phase difference measurement is the basis of grating displacement measurement technique. Traditional Moire fringe subdivision method based on DFT algorithm has low frequency resolution relatively when extracting Moire fringe fundamental frequency spectral line, which causes frequency and phase measurement errors of Moire fringe fundamental frequency. CZT spectrum zoom technique can improve the frequency resolution of frequency band near Moire fringe fundamental frequency and get fundamental frequency spectrum lines more exactly, which can solve the problem of low frequency resolution of DFT. The paper studies the relation of Moire fringe phase difference and grating displacement, and analyzes the working principles of DFT and CZT spectrum zoom method. DFT and CZT spectrum zoom are used for Moire fringe spectrum analysis and phase difference calculation respectively. Simulation results show measurement error of Moire fringe phase difference with DFT algorithm is in 10 -3 degree scale, while measurement error with CZT spectrum zoom algorithm is approximate 0 degree. The comparison results show CZT spectrum zoom method has better performance and applicability, which improves the phase difference measurement accuracy of Moire fringe effectively. DOI: http://dx.doi.org/10.11591/telkomnika.v11i10.3461

Image forming apparatus that uses laser beam

Abstract: An image forming apparatus which is capable of properly correcting a scanning length while suppressing occurrence of moire fringes to reduce degradation of image quality. A laser drive device generates laser beam by driving a laser beam source on an auxiliary pixel basis according to a lighting pattern that defines a pattern for turning on or off the laser beam on an auxiliary pixel basis. A CPU sets the scanning magnification of a photosensitive member in a main scanning direction. Further, the CPU sets the lighting pattern, based on the image data, according to the set scanning magnification, pixel by pixel basis such that the lighting pattern becomes aperiodic in a sequence of pixels. The CPU outputs the lighting pattern to the laser drive device.

Accurate and fast in-plane displacement measurement method for large-scale structures by utilizing repeated pattern

Abstract: Imaging based nondestructive monitoring systems are critical for evaluation of large-scale infrastructures. In this study, an accurate and fast in-plane displacement measurement method based imaging technique is developed for the purpose of health monitoring of large-scale infrastructures such as high building, long bridge, etc. The build-in repeated patterns on infrastructure facade, such as tile, checker, and brick wall pattern is used to measure the in-plane displacement distribution accurately. By performing down-sampling and intensity interpolation image processing to the images captured before and after deformations, multiple phase-shifted moire fringe can be obtained simultaneously. The phase distribution of the moire fringe is calculated using the phase shifting method and discrete Fourier transform technique. In the present study, both the fundamental and high frequency components are considered to analyze the repeated patterns. The in-plane displacement distribution can be obtained from the phase differences of the moire fringe before and after deformations. Compared with conventional displacement methods and sensors, the main advantages of the method developed herein are high-resolution, accurate, fast, low-cost, and easy to implement. The principle of the proposed inplane displacement measurement is presented. The effectiveness of our method is confirmed by a simple displacement measurement experiment. Experimental result showed that a sub-millimeter displacement could be successfully detected for the field of view with meter-scale.

Moire fringe filtering method and device

Abstract: The invention provides a moire fringe filtering method and device. The moire fringe filtering method includes S1, subjecting current images to moire fringe detection, and executing S2 if moire fringes are detected; otherwise, ending the process; and S2, subjecting current images to Gaussian smoothing by using a preset window, and switching to S1 to perform next round of filtering of the moire fringes until preset round numbers are reached, wherein the size of the preset window used in S2 during each round of filtering of the moire fringes is increase progressively. According to the moire fringe filtering method and device, accidental damage on images is reduced as far as possible when the images have no moire fringes, problems of incomplete filtering or excessive filtering caused by improper selection of filtering methods are reduced as far as possible, and overall image distinguishing effects based on moire fringe filtering are improved.

Holographic motherboard manufacturing method and hologram based on moire fringe technology

Abstract: The invention relates to the field of optical holography anti-counterfeiting and in particular to a hologram with a special optical anti-counterfeiting effect generated on the basis of dynamic moire technology and a manufacturing method of a holographic motherboard. According to the moire fringe generated by the invention, fringe grating information is manufactured into a photoetching color graph and a photoetching gray graph by a computer processing means on the basis of a dynamic moire technology principle and then dynamic moire fringe information is transferred to the photoetching motherboard by using laser photoetching equipment. The dynamic moire effect obtained by the method can be identified under natural light; and in addition, the dynamic effect of moire fringe can be controlled, so that higher accuracy and convenience for anti-counterfeiting check of products are realized.

Two-dimensional sampling moiré method for fast and accurate phase analysis of single fringe pattern

Abstract: Phase analysis plays a role in optical science and technology. For instance, phase analysis technique has been widely used for 3-D shape and deformation measurement by fringe projection profilometry. To analyze the phase distribution of a single fringe pattern, various fringe pattern analysis methods such as a Fourier transform, a wavelet transform, and the windowed Fourier transform have been developed. In this study, a fast phase analysis technique, i.e., two-dimensional sampling moire method, is proposed to determine accurately the phase distribution of a single fringe pattern by using two-dimensional intensity information. In this method, we record diagonally a single fringe pattern image by using a CCD camera, and perform the image processing of down-sampling with a sampling pitch and intensity interpolation in both x- and y- directions to generate a two-dimensional phase-shifted moire fringe. Then, the phase distribution of the moire fringe can be determined by using phase-shifting method and a two-dimensional discrete Fourier transform (DFT) algorithm. Finally, the desired phase distribution of the original fringe pattern can be obtained by adding the phase of the sampling point to the phase of the moire pattern. By the proposed method, the phase error caused by the random noise of the camera can be dramatically decreased because the intensity information is much richer than one-dimensional intensity data, which utilizes a two-dimensional DFT algorithm. The fundamental principle and primary simulation and experimental results are presented. Theses results show that phase analysis can be performed under extremely low signal-to-noise ratio measurement condition.

Halftone screening and information hiding algorithm based on the location of dots

Abstract: To solve the defects of interference fringes( namely moire in printing) in printed image that caused easily in information hiding of halftone screening An algorithm was given based on the location of halftone dots which use MQAM( Multiple Quadrature the Amplitude Modulation) to complete information hiding in halftone screening This method not only can solve the moireproblems effectively and optimize the printed image quality,but the information hiding capacity can also be greatly improved The moire can be eliminated by using pseudo-random scrambling and a specific pseudo-random dot template to which encrypt the plaintext information and arrange the location of dots

An image domain approach to the interpretation of the visible moiré phenomenon

Abstract: An approach to the interpretation of the visible moire phenomenon in the image domain has been proposed. The analysis of the Fourier series expansion presents an initial criterion for distinguishing the real moire and pseudo-moire cases. A geometric calculation of the superposed grating lines is utilized to obtain the parameters for describing the real and pseudo-moire cases. On the basis of the study, the average intensities of the waveforms of the real moire and pseudo-moire cases are calculated in order to provide the interpretation. It indicates that different moire cases result from the garbled discernment of human eyes, which is introduced by the microstructure versus macrostructure effects. The variations of intensity and average intensity in the microstructure result in the confusion of the average intensities of the real moire and pseudo-moire waveforms. The interpretation is significant for the visible real and pseudo-moire effects, both in the multiplicative superposition and in the additive superposition composed from periodic cosinusoidal gratings and binary gratings in the image domain. The approach also considers the coexistence of the real moire and pseudo-moire cases. The rule for their coexistence has been summarized in the image domain.

Moiré interferometry method for numerical simulation and applications in three-dimensional metrology-3d

Abstract: The question that dominates and dictates the vision of this work is formed by the low spatial frequencies may appear in the combination of the light distribution of a periodical. The paper describes a method that allows the accurate prediction of the fringe localization in moire. In the case of objects moving as a whole, Moire can be applied thus as a metrological tool. The following applications are considered: study of mechanical vibrations and deformation, micro geometrical properti es of surfaces. Several applications are emphasized: plane, cylindrical and spherical objects. Theoretical predictions are compared with experimental results.

Method for measuring object surface three-dimensional morphology

Abstract: The present invention relates to a method for measuring an object surface three-dimensional morphology. The method belongs to the photomechanics technology field, and comprises the steps of inclining the angle of a scanning electron microscope sample table; obtaining the scanning moire images of a tested sample under different angles; carrying out the moire fringe processing on two images of different inclination angles separately to obtain the displacement fields under the two angles; determining the three-dimensional morphology diagram of the tested sample by utilizing a stereoscopic analysis model formula in a scanning electron microscope and according to the displacement fields. The method for measuring the object surface three-dimensional morphology of the present invention integrates the advantages of high measurement sensitivity and large view field of a scanning moire technology, and can measure the three-dimensional morphology of the object having a micro-nano scale. The method for measuring the object surface three-dimensional morphology of the present invention makes up the insufficient that a conventional scanning electron microscope method only can measure the in-surface information, expands the application range of a scanning moire method, and possesses a very good effect on the measurement of the three-dimensional morphology of the object of micro-nano scale.

Method and device for measuring displacement distribution of an object using repeated pattern, and program for the same

Abstract: In the present invention, conventional problems that the scheme is not suitable for nano/micro materials or large structures, and that if the scheme is applied to a regular pattern with two or more cycles of arbitrary repetition, a large error is generated are solved by using a higher order frequency of moire fringes generated using an arbitrary regular pattern having one-dimensional or two-dimensional repetition artificially produced on a surface of an object or previously present on the surface of the object, or phase information in a plurality of frequency components, and improvement of measurement precision and a dramatic increase in a limit of a measurement scale are achieved.

Focus detecting device based on double-grating moire fringes

Abstract: The invention relates to a focus detecting device based on double-grating moire fringes. The focus detecting device comprises an incident beam, an extender lens, an object grating, wedge-shaped plates, 4f projection systems, rhombic prisms, a detecting grating and a detector, wherein incident light is perpendicularly projected on the object grating by the extender lens; the 4f systems couple an image of the object grating with the detecting grating to form the moire fringes; the height of a silicon wafer can be obtained by detecting movement of the moire fringes; and inclination of the two gratings in the imaging process can be compensated by matching of a double-wedge mirror. The focus detecting device can achieve high-precision and non-contact measurement of the defocusing amount of the silicon wafer.

Color CCD micro moire method for surface deformation measurement

Abstract: The invention discloses a color CCD micro moire method for surface deformation measurement, and belongs to the technical field of experimental mechanics. The color CCD micro moire method for surface deformation measurement is technically characterized in that a standard holographic grating is used for being manufactured into a high-elastic thin film grating, a surface test piece grating is formed after the thin film grating is adhered to the surface of a surface test piece to be measured, a Bayer optical filter in front of a target surface of a color CCD camera is treated as a reference grating, color moire fringes can be formed when the pitch of the image of the surface test piece grating is matched with six lines of units of the Bayer optical filter in the color CCD camera, and a deformation field of the surface test piece is obtained after calculation. The color CCD micro moire method is applied to surface deformation measurement for the first time, therefore, the quality of the CCD moire fringes is improved, and the application range of the moire method is widened. Compared with a strain gage method, the color CCD micro moire method has the advantages that non-contact continuous measurement can be achieved, the measurement area can be smaller, and the efficiency is higher.

Dynamic Shape and Strain Measurements of Rotating Tire in Time-Series

Abstract: Shape measurement and strain distribution measurement are important to analyze the behavior of a rotating tire. A dynamic shape and strain measurement system by the sampling moire method was developed. Recently, phase analysis method using phase-shifting moire patterns generated in a computer from a grating image is proposed. This method is very suitable for dynamic measurement because the phase can be obtained from a one-dimensional or two-dimensional grating image with high accuracy. It is possible to analyze strain distribution and shape measurement of a moving object using a grating pattern attached on the specimen surface. A dynamic shape and strain measurement system by the sampling moire method is developed. In this paper, we applied high-speed cameras to this method. The behavior when a tire got over a projection with high-speed rotating was observed as time-series data. The principle and experimental results are shown.