Real-time heterodyne imaging interferometry: focal-plane amplitude and phase demodulation using a three-phase correlation image sensor

A method of real-time heterodyne imaging interferometry using a three-phase correlation image sensor (3PCIS) is proposed. It simultaneously demodulates the amplitude and phase images of an incident interference pattern at an ordinary frame rate with good accuracy, thus overcoming the trade-off among measurement time, spatial resolution, and demodulation accuracy suffered in conventional interferometry. An experimental system is constructed with a 64x64 3PCIS camera operated at 30 frames/s and a two-frequency He-Ne laser with a beat frequency of 25 kHz. The results obtained for a scanning mirror and heated silicone oil confirm the proposed method.     

Four-Channel, 8 x 8 Bit, Two-Dimensional Parallel Transmission by use of Space-Code-Division Multiple-Access Encoder and Decoder Modules

We experimentally demonstrate four-channel multiplexing of 64-bit (8 x 8) two-dimensional (2-D) parallel data links on the basis of optical space-code-division multiple access (CDMA) by using new modules of optical spatial encoders and a decoder with a new high-contrast 9-m-long image fiber with 3 x 10(4) cores. Each 8 x 8 bit plane (64-bit parallel data) is optically encoded with an 8 x 8, 2-D optical orthogonal signature pattern. The encoded bit planes are spatially multiplexed and transmitted through an image fiber. A receiver can recover the intended input bit plane by means of an optical decoding process. This result should encourage the application of optical space-CDMA to future high-throughput 2-D parallel data links connecting massively parallel processors.     

Image fiber optic space-CDMA parallel transmission experiment using 8 x 8 VCSEL/PD arrays

We experimentally demonstrate space-code-division multiple access (space-CDMA) based twodimensional (2-D) parallel optical interconnections by using image fibers and 8 x 8 vertical-cavity surface-emitting laser (VCSEL)/photo diode (PD) arrays. Two spatially encoded four-bit (2 x 2) parallel optical signals were emitted fiom 2-D VCSEL arrays and transmitted through image fibers. The encoded signals were multiplexed by an image-fiber coupler and detected by a 2-D PD array on the receiver side. The receiver recovered the intended parallel signal by decoding the signal. The transmission speed was 64 Mbps/ch (total throughput: 512 Mbps). Bit-error-rate (BER) measurement with a laterally misaligned PD array showed the array had a misalignment tolerance of 25 microm for a BER performance of 10(-9).     

Optimization of fringe pattern calculation with direct correlations in speckle interferometry

A direct correlation technique is used to calculate correlation fringe patterns from consecutive speckle patterns acquired with a dual-beam electronic speckle interferometer. Although more calculations are required than in standard image differencing routines, an advantage of the method is that the illumination over the surface of the object need not be uniform. In the method, Pearson's coefficient of correlation between the intensities within a set of adjacent pixels is calculated. This has the added advantage of being directly related to the theoretical phase-dependent correlation. A mapping of this measure of correlation results in the correlation fringe pattern. Laboratory tests were carried out with in-plane translations ranging from 5 to 45 mum. The correlation calculations were carried out by using cells (square sets of pixels) in the raw speckle images with dimensions ranging from 2 pixels x 2 pixels to 19 pixels x 19 pixels. Both cell dimension and translation magnitude dependent decorrelation effects influence the quality of the correlation fringe patterns.     

论汉字的书写速度

随着科学技术的进步，越来越多的工作变成丁脑力劳动类型的工作。由于汉字是人们在工作中进行信息交流的基本媒介之一，因此研究汉字的使用效率问题对研究脑力工作的效率就显得十分必要。本文研究的是一个最基本的问题，即汉字的书写速度。34个大学生作为被试者参加丁在我们实验室进行的汉字书写速度试验，他们被要求用3种不同的方式书写4个笔划不同的汉字，每个汉字重复写1分钟。试验数据分析表明，写字的速度随字的笔划的多少和书写方式变化很大。如果用正常速度(行书的方式)，根据汉字的平均笔划，我们算出每分钟大约可以写25个字左右。我们还给出了在不同书写方式下写汉字的速度与汉字笔划的一元线性回归方程，最后我们对数据的实用范围和注意事项进行了讨论。     

Determination of neutron energy spectra inside a water phantom irradiated by 64 MeV neutrons

A NE230 deuterated liquid scintillator detector (25 mm diameter x 25 mm) has been used to investigate neutron energy spectra as a function of position in a water phantom under irradiation by a quasi-monoenergetic 64 MeV neutron beam. Neutron energy spectra are obtained from measurements of pulse height spectra by the NE230 detector using the Bayesian unfolding code MAXED. The experimentally measured energy spectra are compared with spectra calculated by Monte Carlo simulation using the code MCNPX.     

Feature-extracted joint transform correlation

A new technique for real-time optical character recognition that uses a joint transform correlator is proposed. This technique employs feature-extracted patterns for the reference image to detect a wide range of characters in one step. The proposed technique significantly enhances the processing speed when compared with the presently available joint transform correlator architectures and shows feasibility for multichannel joint transform correlation.     

EMS表单中手写体中文识别图像预处理方法研究

目的在脱机手写体文字识别系统中,由于自由书写的字符不可避免地受到图像背景不均匀、图像倾斜和字符粘连及大小不一等因素的影响,为了确保字符切分和识别的正确性,对EMS表单中手写体汉字字符图像预处理方法进行探讨,展示了EMS表单图像预处理的全过程。方法采用最小二乘法作拟合直线的方法,对目标图像进行定位和分割,用基于大津阈值的分块阈值算法处理目标图像的背景不均问题,并减少噪声干扰。结果该图像预处理方法在1020张真实EMS图像上进行测试,识别正确率达到了86.3%。结论该方法有一定的灵活性和抗干扰性,减少了图像噪声对汉字字符切分和识别的影响。     

Performance analysis of multiple-input multiple-output orthogonal frequency division multiplexing systems under the influence of antenna mutual coupling effect

The effect of antenna mutual coupling on signal correlation and bit error rate (BER) of a multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system has been modelled. A MIMOOFDM model with correlated channels is presented. The correlation matrices are determined with the antenna mutual coupling taken into account. The effect of antenna mutual coupling is characterised using the receiving and transmitting mutual impedances. A rigorous expression for the BER of the system employing quadrature phase-shift keying digital modulation is derived. A 2 x 2 MIMO-OFDM system using the Alamouti space?time block code for OFDM symbol transmission over 64 sub-channels spanning a 20 MHz band centred at 5.2 GHz is simulated. The simulated results show that the antenna mutual coupling has a significant effect on the BER performance, especially when the spacing between the antenna elements is small.     

Volumetric ultrasound imaging using 2-D CMUT arrays

Recently, capacitive micromachined ultrasonic transducers (CMUTs) have emerged as a candidate to overcome the difficulties in the realization of 2-D arrays for real-time 3-D imaging. In this paper, we present the first volumetric images obtained using a 2-D CMUT array. We have fabricated a 128 x 128-element 2-D CMUT array with through-wafer via interconnects and a 420-microm element pitch. As an experimental prototype, a 32 x 64-element portion of the 128 x 128-element array was diced and flip-chip bonded onto a glass fanout chip. This chip provides individual leads from a central 16 x 16-element portion of the array to surrounding bondpads. An 8 x 16-element portion of the array was used in the experiments along with a 128-channel data acquisition system. For imaging phantoms, we used a 2.37-mm diameter steel sphere located 10 mm from the array center and two 12-mm-thick Plexiglas plates located 20 mm and 60 mm from the array. A 4 x 4 group of elements in the middle of the 8 x 16-element array was used in transmit, and the remaining elements were used to receive the echo signals. The echo signal obtained from the spherical target presented a frequency spectrum centered at 4.37 MHz with a 100% fractional bandwidth, whereas the frequency spectrum for the echo signal from the parallel plate phantom was centered at 3.44 MHz with a 91% fractional bandwidth. The images were reconstructed by using RF beamforming and synthetic phased array approaches and visualized by surface rendering and multiplanar slicing techniques. The image of the spherical target has been used to approximate the point spread function of the system and is compared with theoretical expectations. This study experimentally demonstrates that 2-D CMUT arrays can be fabricated with high yield using silicon IC-fabrication processes, individual electrical connections can be provided using through-wafer vias, and flip-chip bonding can be used to integrate these dense 2-D arrays with electronic circuits for practical 3-D imaging applications.     

Time-resolved Fourier transform infrared spectroscopy of chemical reactions in solution using a focal plane array detector

A Fourier transform infrared (FT-IR) microscope equipped with a single as well as a 64 x 64 element focal plane array MCT detector was used to measure chemical reaction taking place in a microstructured flow cell designed for time-resolved FT-IR spectroscopy. The flow cell allows transmission measurements through aqueous solutions and incorporates a microstructured mixing unit. This unit achieves lamination of the two input streams with a cross-section of 300 x 5 microm each, resulting in fast diffusion-controlled mixing of the two input streams. Microscopic measurement at defined positions along the outlet channel allows time-resolved information of the reaction taking place in the flow cell to be obtained. In this paper we show experimental results on the model reaction between formaldehyde and sulfite. Using the single-point MCT detector, high-quality FT-IR spectra could be obtained from a spot size of 80 x 200 microm whereas the FPA detector allowed recording light from an area of 260 x 260 microm focused on its 64 x 64 detector elements. Therefore, more closely spaced features could be discerned at the expense of a significantly lower signal-to-noise (S/N) ratio per spectrum. Multivariate curve resolution-alternating least squares was used to extract concentration profiles of the reacting species along the outlet channel axis.     

Spatial analysis of time of flight-secondary ion mass spectrometric images by ordinary kriging and inverse distance weighted interpolation techniques

Ordinary kriging and inverse distance weighted (IDW) are two interpolation methods for spatial analysis of data and are commonly used to analyze macroscopic spatial data in the fields of remote sensing, geography, and geology. In this study, these two interpolation techniques were compared and used to analyze microscopic chemical images created from time of flight-secondary ion mass spectrometry images from a patterned polymer sample of fluorocarbon (C(x)F(y)) and poly(aminopropyl siloxane) (APS, a.k.a. siloxane). Data was eliminated from the original high-resolution data set by successive random removal, and the image file was interpolated and reconstructed with a random subset of points using both methods. The statistical validity of the reconstructed image was determined by both standard geographic information system (GIS) validation statistics and evaluating the resolution across an image boundary using ASTM depth and image resolution methodology. The results show that both ordinary kriging and IDW techniques can be used to accurately reconstruct an image using substantially fewer sample points than the original data set. Ordinary kriging performed better than the IDW technique, resulting in fewer errors in predicted intensities and greater retention of original image features. The size of the data set required for the most accurate reconstruction of the original image is directly related to the autocorrelation present within the data set. When 10% of the original siloxane data set was used for an ordinary kriging interpolation, the resulting image still retained the characteristic gridlike pattern. The C(x)F(y) data set exhibited stronger spatial correlation, resulting in reconstruction of the image with only 1% of the original data set. The removal of data points does result in a loss of image resolution; however, the resolution loss is not directly related to the percentage of sample points removed.     

Finite element formulation for a digital image correlation method

A finite element formulation for a digital image correlation method is presented that will determine directly the complete, two-dimensional displacement field during the image correlation process on digital images. The entire interested image area is discretized into finite elements that are involved in the common image correlation process by use of our algorithms. This image correlation method with finite element formulation has an advantage over subset-based image correlation methods because it satisfies the requirements of displacement continuity and derivative continuity among elements on images. Numerical studies and a real experiment are used to verify the proposed formulation. Results have shown that the image correlation with the finite element formulation is computationally efficient, accurate, and robust.     

Experimental systems implementation of a hybrid optical-digital correlator

A high-speed hybrid optical-digital correlator system was designed, constructed, modeled, and demonstrated experimentally. This correlator is capable of operation at approximately 3000 correlations/s. The input scene is digitized at a resolution of 512 x 512 pixels and the phase information of the two-dimensional fast Fourier transform calculated and displayed in the correlator filter plane at normal video frame rates. High-fidelity reference template images are stored in a phase-conjugating optical memory placed at the nominal input plane of the correlator and reconstructed with a high-speed acousto-optic scanner; this allows for cross correlation of the entire reference data set with the input scene within one frame period. A high-speed CCD camera is used to capture the correlation-plane image, and rapid correlation-plane processing is achieved with a parallel processing architecture.     

基于模糊非线性回归算法的图像复原

为了利用多幅具有相似降质特性的退化图像信息恢复出原图像,提出了一种新的基于模糊参量非线性回归估计的图像盲复原算法。 该算法充分利用多幅图像具有的相似降质特征,首先给出一种非理想光照分布参数的模糊非线性回归估计方法,然后通过估计出的参数得到与原图同样大小的非理想光照分布图,最后通过观测图像与非理想光照分布图相消的方法,对退化图像进行复原。 实验结果表明,该算法运算快速,对边缘细节及平滑区域均有良好的修复能力,在修复效果上明显优于一般图像修复算法。     

基于生成对抗网络的风格化书法图像生成

目的为修复书法图像中的残缺字体,提出一种提取书法图像特征并自动生成风格化书法图像的方法。方法首先针对书法作品的灰度图像利用变分自编码器提取字体的形状特征,同时将书法图像转换至Lab颜色空间中,通过四层卷积神经网络模型对L通道进行深度学习,提取书法字体中的风格特征;然后将风格特征作为条件输入,与形状特征一起输入生成对抗网络的生成器中进行联合训练,使生成的字体带有特定风格。研究过程中构建一个包含不同风格书法字体的中国书法字体生成数据集(CCGD-2019)用作模型训练。结果提出了一种基于变分自编码与生成对抗网络的书法字体图像生成模型,能够从标准字体或随机噪声自动生成风格化书法字体图像。结论人眼主观评价及Fréchet初始距离计算结果表明,生成字体的识别率和视觉质量均达到了令人满意的效果。     

Kinetics of antigen binding to arrays of antibodies in different sized spots

A fluorescence-based array biosensor has been developed which can measure the binding kinetics of an antigen to an immobilized antibody in real time. A patterned array of antibodies immobilized on the surface of a planar waveguide was used to capture a Cy5-labeled antigen present in a solution that was continuously flowed over the surface. The CCD image of the waveguide was monitored continuously for 25 min. The resulting exponential rise in fluorescence signal was determined by image analysis software and fitted to a reaction-limited kinetics model, giving a kf of 3.6 x 10(5) M(-1) s(-1). Different spot sizes were then patterned on the surface of the waveguide using either a PDMS flow cell or laser exposure, producing width sizes ranging from 80 to 1145 microm. It was demonstrated that under flow conditions, the reduction of spot size did not alter the association rate of the antigen with immobilized antibody; however, as the spot width decreased to < 200 nm, the signal intensity also decreased.     

Kernel-based spectral color image segmentation

In this work, we propose a new algorithm for spectral color image segmentation based on the use of a kernel matrix. A cost function for spectral kernel clustering is introduced to measure the correlation between clusters. An efficient multiscale method is presented for accelerating spectral color image segmentation. The multiscale strategy uses the lattice geometry of images to construct an image pyramid whose hierarchy provides a framework for rapidly estimating eigenvectors of normalized kernel matrices. To prevent the boundaries from deteriorating, the image size on the top level of the pyramid is generally required to be around 75 x 75, where the eigenvectors of normalized kernel matrices would be approximately solved by the Nystr?m method. Within this hierarchical structure, the coarse solution is increasingly propagated to finer levels and is refined using subspace iteration. In addition, to make full use of the abundant color information contained in spectral color images, we propose using spectrum extension to incorporate the geometric features of spectra into similarity measures. Experimental results have shown that the proposed method can perform significantly well in spectral color image segmentation as well as speed up the approximation of the eigenvectors of normalized kernel matrices.     

Spatially resolved detection of attomole quantities of organic molecules localized in picoliter vials using time-of-flight secondary ion mass spectrometry.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) has been utilized to detect femtomole and attomole quantities of organic species from within silicon nanovials. By using high-density arrays (10,000 nanovials/cm2) it is possible to chemically characterize diverse sample sets within a single chemical image. Molecular sensitivities, for the compounds investigated, very between 85 attomoles and 25 femtomoles, and typical acquisition times are approximately 100 ms per nanovial. These vials are fabricated using photolithography and KOH etching of Si[001] wafers to create wells, with a pyramidal cross section, ranging in size from 25 to 5625 micron 2. The volume ranges from 30 femtoliters to 100 picoliters, respectively. A drawn glass microinjector and solenoid-driven dispenser are utilized to array picoliter volumes of organic compounds into individual silicon nanovials. Solution concentrations typically range from 1 x 10(-2) to 1 x 10(-4) M allowing femtomole and even attomole quantities of material to be dispensed into each vial.     

Dynamic optical coupled system employing even-numbered dammann gratings

Dammann gratings are well known for their ability to generate arrays of uniform-intensity beams from an incoming monochromatic beam. We apply the even-numbered Dammann grating to achieve dynamic optical coupled technology. A 1 x N dynamic optical coupled system is developed by employing two complementary even-numbered Dammann gratings. With this system we can achieve a beam splitter and combiner as a switch between them according to the relative shift between the gratings. Also, this system is a preferable approach in integral packaging. More importantly, this device has the potential to be applied to the splitting of a large array, e.g., 8 x 16 array and 64 x 64 array, which is difficult to be realized with conventional splitting methods. We experimentally demonstrated a 1 x 8 coupler at the wavelength of 1550 nm. Furthermore we analyze the effects of the alignment errors between gratings and the wavelength-dependent error on efficiency and uniformity. The experimental results and the influence of alignment error and wavelength-dependent error are analyzed in detail.