- 标题
- 摘要
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- 实验方案
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Hyperspectral holographic microscopy of bio-objects based on a modified Linnik interferometer
摘要： We present a modified Linnik microinterferometer that can register image-plane hyperspectral holograms in reflection of various microobjects in incoherent light. A voice coil was integrated into the reference arm of the interferometer to enable mirror displacement. A set of interferograms is registered in each pixel of a high-speed CMOS camera. Post processing yields spectrally resolved image-plane holograms of the object. Quantitative phase images of red blood cells are obtained for each spectral component σ = 1/λ.
关键词： microscopy,Linnik interferometer,holography,white light interferometry,Fourier transform microspectroscopy
更新于2025-09-23 15:23:52
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Research on the acquisition of time‐reversed electromagnetic waves based on Fourier transform theory
摘要： This paper mainly researches on the realization of time reversal mirror (TRM) based on the analog signal processing technology. Using chirped dispersive delay lines (CDDL) and based on Fourier transform theory, the solution for achieving time reversal (TR) waveform transformation has been concept proposed and theoretically analyzed. Furthermore, using two designed delay lines with the slope of ?0.4 ns/GHz, the paper experimentally achieves time-reversed waveform for a microwave signal with the time length of 1 ns. Compared to conventional implementation scheme systems with CDDLs, the newly suggested one is more stable with higher time-bandwidth products and is able to process longer time duration and wider bandwidth, which provide theoretical basis for physically achieving time-reversed systems.
关键词： dispersive delay line,time reversal mirror,Fourier transform theory,time reversal
更新于2025-09-23 15:23:52
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An Extension of Phase Correlation-Based Image Registration to Estimate Similarity Transform Using Multiple Polar Fourier Transform
摘要： Image registration is a core technology of many different image processing areas and is widely used in the remote sensing community. The accuracy of image registration largely determines the effect of subsequent applications. In recent years, phase correlation-based image registration has drawn much attention because of its high accuracy and ef?ciency as well as its robustness to gray difference and even slight changes in content. Many researchers have reported that the phase correlation method can acquire a sub-pixel accuracy of 1/10 or even 1/100. However, its performance is acquired only in the case of translation, which limits the scope of the application of the method. However, there are few reports on the estimation of scales and angles based on the phase correlation method. To take advantage of the high accuracy property and other merits of phase correlation-based image registration and extend it to estimate the similarity transform, we proposed a novel algorithm, the Multilayer Polar Fourier Transform (MPFT), which uses a fast and accurate polar Fourier transform with different scaling factors to calculate the log-polar Fourier transform. The structure of the polar grids of MPFT is more similar to the one of the log-polar grid. In particular, for rotation estimation only, the polar grid of MPFT is the calculation grid. To validate its effectiveness and high accuracy in estimating angles and scales, both qualitative and quantitative experiments were carried out. The quantitative experiments included a numerical simulation as well as synthetic and real data experiments. The experimental results showed that the proposed method, MPFT, performs better than the existing phase correlation-based similarity transform estimation methods, the Pseudo-polar Fourier Transform (PPFT) and the Multilayer Fractional Fourier Transform method (MLFFT), and the classical feature-based registration method, Scale-Invariant Feature Transform (SIFT), and its variant, ms-SIFT.
关键词： similarity transform,image registration,Polar Fourier Transform,phase correlation,Log-polar Fourier Transform
更新于2025-09-23 15:22:29
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Double Quantum Image Encryption Based on Arnold Transform and Qubit Random Rotation
摘要： Quantum image encryption offers major advantages over its classical counterpart in terms of key space, computational complexity, and so on. A novel double quantum image encryption approach based on quantum Arnold transform (QAT) and qubit random rotation is proposed in this paper, in which QAT is used to scramble pixel positions and the gray information is changed by utilizing random qubit rotation. Actually, the independent random qubit rotation operates once, respectively, in spatial and frequency domains with the help of quantum Fourier transform (QFT). The encryption process accomplishes pixel confusion and diffusion, and finally the noise-like cipher image is obtained. Numerical simulation and theoretical analysis verify that the method is valid and it shows superior performance in security and computational complexity.
关键词： quantum image representation,quantum Fourier transform,quantum image encryption,Arnold transform,information security
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Detection of Uniformly Accelerated Spinning Target Based on OAM Beams
摘要： In recent years, it has been validated that electromagnetic (EM) wave carrying orbital angular momentum (OAM) can be exploited to detect the angular velocity of spinning targets with uniform velocity. In this paper, the detection method of uniformly accelerated spinning target using OAM beams is studied. The time-frequency analysis approaches, including the Wigner-Ville distribution (WVD) and the fractional order Fourier transform (FRFT), are used to analyze the rotational Doppler frequency shift caused by spinning targets. Simulation results indicate that the resolution of acceleration is dependent on the spectrum width of time-frequency diagrams of the echo signal.
关键词： OAM beams,rotational Doppler frequency shift,uniformly accelerated spinning target,Wigner-Ville distribution,fractional order Fourier transform
更新于2025-09-23 15:22:29
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[IEEE 2018 41st International Conference on Telecommunications and Signal Processing (TSP) - Athens, Greece (2018.7.4-2018.7.6)] 2018 41st International Conference on Telecommunications and Signal Processing (TSP) - Improvement of Optic Disc Localization using Gabor Filters
摘要： The paper presents a supervised technique for the detection and localization of the optic disc (OD) in retinal images. The proposed processing technique is based on Discrete Fourier Transform (DFT) and Gabor filters (GFs). The algorithm of image patch processing and classification has two phases: the learning phase for the OD class definition and the testing phase for the patch processing and classification. Two features are used to check if a patch contains the OD: the magnitude and the phase values computed on the result of the convolution between the DFT of the patch and the bank of Gabor filters. Over 100 images from MESSIDOR database were tested and comparing with other similar works. The proposed algorithm gave better results in terms of accuracy of the OD localization for all types of OD.
关键词： Gabor filter,feature extraction,Discrete Fourier Transform,patch decomposition,optic disc localization
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Highly Squinted Imaging for Diving SAR with 3-Dacceleration
摘要： A uniform linear motion is generally assumed in traditional synthetic aperture radar(SAR) processing algorithms. However, it is inevitable that if there is 3-D acceleration, the image formulation processing complexity will be significantly increased, especially in highly squinted situations. This paper aims to handle the imaging problems in the highly squinted SAR with three-dimensional acceleration, which utilizes the Taylor formula to expand the distance equation and further resolve it. Based on the formulated range formula, we further utilize the two-dimensional non-uniform Fast Fourier Transform (2D-NUFFT) to obtain focused SAR imagery. The proposed methods are verified with simulation results.
关键词： 2D-NUFFT algorithm,highly squinted,synthetic aperture radar (SAR),nonuniform fast Fourier transform (NUFFT),3-D acceleration model
更新于2025-09-23 15:22:29
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Green method by diffuse reflectance infrared spectroscopy and spectral region selection for the quantification of sulphamethoxazole and trimethoprim in pharmaceutical formulations
摘要： An alternative method for the quantification of sulphametoxazole (SMZ) and trimethoprim (TMP) using diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and partial least square regression (PLS) was developed. Interval Partial Least Square (iPLS) and Synergy Partial Least Square (siPLS) were applied to select a spectral range that provided the lowest prediction error in comparison to the full-spectrum model. Fifteen commercial tablet formulations and forty-nine synthetic samples were used. The ranges of concentration considered were 400 to 900 mg g-1 SMZ and 80 to 240 mg g-1 TMP. Spectral data were recorded between 600 and 4000 cm-1 with a 4 cm-1 resolution by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The proposed procedure was compared to high performance liquid chromatography (HPLC). The results obtained from the root mean square error of prediction (RMSEP), during the validation of the models for samples of sulphamethoxazole (SMZ) and trimethoprim (TMP) using siPLS, demonstrate that this approach is a valid technique for use in quantitative analysis of pharmaceutical formulations. The selected interval algorithm allowed building regression models with minor errors when compared to the full spectrum PLS model. A RMSEP of 13.03 mg g-1 for SMZ and 4.88 mg g-1 for TMP was obtained after the selection the best spectral regions by siPLS.
关键词： green analytical method,diffuse reflectance infrared Fourier transform spectroscopy,interval partial least squares (iPLS),chemometrics,synergy partial least squares (siPLS),high performance liquid chromatography
更新于2025-09-23 15:22:29
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The feasibility of applying NIR and FT-IR fingerprinting to detect adulteration in black pepper
摘要： Black pepper is the most widely used spice in the world. Spices are highly vulnerable to economically motivated adulteration as they are high value products and traded along complex supply chains. The main fraud opportunity is to add cheaper bulking materials. Near and Fourier-Transform Infrared Spectroscopy has been combined with chemometrics to screen for the substitution of black pepper with papaya seeds, chili and with non-functional black pepper material such as black pepper husk, pinheads and defatted spent materials. A good separation performance between black pepper and adulterated samples could be shown. After running a binary classification model with an external test set an area under the receiver operator characteristic curve of 0.98 for both, the NIR and FT-IR model was obtained. This study shows the huge potential for a fast and rapid screening method that can be used to prove the authenticity of black pepper and detect adulterants.
关键词： Black Pepper,Screening method,Adulteration,Fourier transform infrared,Near infrared,Authenticity
更新于2025-09-23 15:22:29
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Optical properties and colorimetry of gelatine gels prepared in different saline solutions
摘要： Gelatine has been widely used in many multidisciplinary research fields due to its biocompatibility. Using saline solutions in the gelation of gelatine allows for new properties to be incorporated into the prepared gels. This study examined the optical and colour properties of gelatine gels prepared in saline solutions, containing three different metal chlorides (NiCl2·6H2O, CoCl2·6H2O, and CrCl3·6H2O) with concentrations of up to 50%, to prepare three groups of gels. FTIR spectroscopy indicated a loss in the helical structure of the metal-containing gelatine gels, and a shift in the amide bands towards lower wavenumbers. From the thermogravimetric analysis (TGA), the starting degradation temperatures (SDTs) of the prepared gelatine gels were found to be correlated to the concentration of the gelling solutions. All SDTs were above 250 °C, making these gels suitable for standing temperatures beyond the daily range. UV–vis spectroscopy showed that d-d transitions were responsible for the colour properties of the metal-containing gelatine gels. It is concluded that the studied properties and the measured parameters were found to depend on both salt type and concentration. With the current findings, the prepared gels can be used as optical thermometers, colour-selective corner cube retroreflectors, laser components, and coatings for OLEDs.
关键词： Colour parameters,Fourier transform infrared spectroscopy,Optical properties,Gelatine,Transition metals,Thermogravimetric analysis
更新于2025-09-23 15:22:29