Enhancing seismic resolution is a key component in seismic data processing, which plays a valuable role in raising the prospecting accuracy of oil reservoirs. However, in noisy situations, existing resolution enhancem...Enhancing seismic resolution is a key component in seismic data processing, which plays a valuable role in raising the prospecting accuracy of oil reservoirs. However, in noisy situations, existing resolution enhancement methods are difficult to yield satisfactory processing outcomes for reservoir characterization. To solve this problem, we develop a new approach for simultaneous denoising and resolution enhancement of seismic data based on convolution dictionary learning. First, an elastic convolution dictionary learning algorithm is presented to efficiently learn a convolution dictionary with stronger representation capability from the noisy data to be processed. Specifically, the algorithm introduces the elastic L1/2 norm as a sparsity constraint and employs a steepest gradient descent strategy to efficiently solve the frequency-domain linear system with substantial computational cost in a half-quadratic splitting framework. Then, based on the learned convolution dictionary, a weighted convolutional sparse representation paradigm is designed to encode the noisy data to acquire an optimal sparse approximation of the effective signal. Subsequently, a high-resolution dictionary with a broadband spectrum is constructed by the proposed parameter scaling strategy and matched filtering technique on the basis of atomic spectrum modeling. Finally, the optimal sparse approximation of the effective signal and the constructed high-resolution dictionary are used for data reconstruction to obtain the seismic signal with high resolution and high signal-to-noise ratio. Synthetic and field dataset examples are executed to check the effectiveness and reliability of the developed method. The results indicate that this method has a more competitive performance in seismic applications compared with the conventional deconvolution and spectral whitening methods.展开更多
A scheme for fourth-order double-slit ghost interference with a pseudo-thermal light source is proposed. It is shown that not only can the visibility be dramatically enhanced compared to the third-order case, but also...A scheme for fourth-order double-slit ghost interference with a pseudo-thermal light source is proposed. It is shown that not only can the visibility be dramatically enhanced compared to the third-order case, but also higher resolution is demonstrated if we scan two of three reference detectors in opposite directions with the same speed, meanwhile another two in identical directions where the speed of one reference detector is twice the other. The results show that the visibility and resolution improvement of the fourth-order ghost interference fringe can be applied to the Nth-order ghost imaging.展开更多
Digital holographic microscopy(DHM),which combines digital holography with optical microscopy,is a wide field,minimally invasive quantitative phase microscopy(QPM)approach for measuring the 3D shape or the inner struc...Digital holographic microscopy(DHM),which combines digital holography with optical microscopy,is a wide field,minimally invasive quantitative phase microscopy(QPM)approach for measuring the 3D shape or the inner structure of transparent and translucent samples.However,limited by diffraction,the spatial resolution of conventional DHM is relatively low and incompatible with a wide field of view(FOV)owing to the spatial bandwidth product(SBP)limit of the imaging systems.During the past decades,many efforts have been made to enhance the spatial resolution of DHM while preserving a large FOV by trading with unused degrees of freedom.Illumination modulation techniques,such as oblique illumination,structured illumination,and speckle illumination,can enhance the resolution by adding more high-frequency information to the recording system.Resolution enhancement is also achieved by extrapolation of a hologram or by synthesizing a larger hologram by scanning the sample,the camera,or inserting a diffraction grating between the sample and the camera.For on-chip DHM,spatial resolution is achieved using pixel super-resolution techniques.In this paper,we review various resolution enhancement approaches in DHM and discuss the advantages and disadvantages of these approaches.It is our hope that this review will contribute to advancements in DHM and its practical applications in many fields.展开更多
In optical scanning holography, one pupil produces a spherical wave and another produces a plane wave. They interfere with each other and result in a fringe pattern for scanning a three-dimensional object. The resolut...In optical scanning holography, one pupil produces a spherical wave and another produces a plane wave. They interfere with each other and result in a fringe pattern for scanning a three-dimensional object. The resolution of the hologram reconstruction is affected by the point spread function(PSF) of the optical system. In this paper, we modulate the PSF by a spiral phase plate, which significantly enhances the lateral and depth resolution. We explain the theory for such resolution enhancement and show simulation results to verify the efficacy of the approach.展开更多
We propose a single-pixel imaging(SPI)method to achieve a higher-resolution image via the Hadamard transform matrix.Unlike traditional SPI schemes,this new method recovers images by correlating single-pixel signals wi...We propose a single-pixel imaging(SPI)method to achieve a higher-resolution image via the Hadamard transform matrix.Unlike traditional SPI schemes,this new method recovers images by correlating single-pixel signals with synchronized transformed patterns of Hadamard bases that are actually projected onto the digital micromirror device.Each transform pattern is obtained through the inverse Fourier transform of the pattern acquired by Gaussian filtering of each Hadamard basis in the frequency domain.The proposed scheme is based on a typical SPI experimental setup and does not add any hardware complexity,enabling the transformation of Hadamard matrices and image reconstruction through data processing alone.Therefore,this approach could be considered as an alternative option for achieving fast SPI in a diffraction-limited imaging system,without the need for additional hardware.展开更多
High accuracy and time resolution optical transfer delay(OTD)measurement is highly desired in many multi-path applications,such as optical true-time-delay-based array systems and distributed optical sensors.However,th...High accuracy and time resolution optical transfer delay(OTD)measurement is highly desired in many multi-path applications,such as optical true-time-delay-based array systems and distributed optical sensors.However,the time resolution is usually limited by the frequency range of the probe signal in frequency-multiplexed OTD measurement techniques.Here,we proposed a time-resolution enhanced OTD measurement method based on incoherent optical frequency domain reflectometry(I-OFDR),where an adaptive filter is designed to suppress the spectral leakage from other paths to break the resolution limitation.A weighted least square(WLS)cost function is first established,and then an iteration approach is used to minimize the cost function.Finally,the appropriate filter parameter is obtained according to the convergence results.In a proof-of-concept experiment,the time-domain response of two optical links with a length difference of 900 ps is successfully estimated by applying a probe signal with a bandwidth of 400 MHz.The time resolution is improved by 2.78times compared to the theoretical resolution limit of the inverse discrete Fourier transform(iDFT)algorithm.In addition,the OTD measurement error is below±0.8 ps.The proposed algorithm provides a novel way to improve the measurement resolution without applying a probe signal with a large bandwidth,avoiding measurement errors induced by the dispersion effect.展开更多
We describe a post resolution-enhancement-technique verification method for use in manufacturing data flow. The goal of the method is to verify whether designs function as intended,or more precisely, whether the print...We describe a post resolution-enhancement-technique verification method for use in manufacturing data flow. The goal of the method is to verify whether designs function as intended,or more precisely, whether the printed images are consistent with the design intent. The process modeling is described for the model-based verifi cation method. The performance of the method is demonstrated by experiment.展开更多
Based on dual-frequencies dual-apertures spaceborne SAR （Synthetic Aperture Radar）, a new SAR system with four receiving channels and two operation modes is presented in this paper, SAR imaging and Moving Target Ind...Based on dual-frequencies dual-apertures spaceborne SAR （Synthetic Aperture Radar）, a new SAR system with four receiving channels and two operation modes is presented in this paper, SAR imaging and Moving Target Indication （MTI） are studied in this system. High resolution imaging with wide swath is implemented by the Mode Ⅰ, and MTI is completed by the Mode Ⅱ. High azimuth resolution is achieved by the Displaced Phase Center （DPC） multibeam technique. And the Coherent Accumulation （CA） method, which combines dual channels data of different carrier frequency, is used to enhance the range resolution. For the data of different carrier frequency, the two aperture interferometric processing is executed to implement clutter cancellation, respectively. And the couple of clutter suppressed data are employed to implement Dual Carrier Frequency Conjugate Processing （DCFCP）, then both slow and fast moving targets detection can be completed, followed by moving target imaging. The simulation results show the validity of the signal processing method of this new SAR system.展开更多
We introduce a phase-only hologram generation method based on an integral imaging, and propose an enhancement method in representable depth interval. The computational integral imaging reconstruction method is modifie...We introduce a phase-only hologram generation method based on an integral imaging, and propose an enhancement method in representable depth interval. The computational integral imaging reconstruction method is modified based on optical flow to obtain depth-slice images for the focused objects only. A phaseonly hologram for＇ multiple plane images is generated using the iterative Fresnel transform algorithm. In addition, a division method in hologram plane is proposed for enhancement in the representable minimum depth interval.展开更多
Microwave radiometers have many applications because of their penetration ability. However, two major problems remain that obstruct the development of microwave research. One factor that limits their commercial applic...Microwave radiometers have many applications because of their penetration ability. However, two major problems remain that obstruct the development of microwave research. One factor that limits their commercial application is the relatively low resolution of microwave radiometers. The other is the non-uniform spatial resolution for each frequency of the radiometer. The resolution mismatch becomes a critical consideration when observations at two or more frequencies must be combined. In this paper, we have used the Backus-Gilbert method to solve these two problems, while AMSR-E is chosen as the research object. First, we derived the Backus-Gilbert method in detail. The simulated data were then used to decide the optimum parameters in the Backus-Gilbert method. To enhance the resolution, the Backus-Gilbert method has been applied to the AMSR-E data, which covered the Mexico Gulf and the Amazon River. After resolution was enhanced, detailed information was obtained and compared with visible high resolution data. To match the resolution, the AMSR-E data from the Oklahoma Little Washed were used to compute the Microwave Vegetation Index (MVI), which was developed by J. C. Shi. Compared to the original MVIs, the information contained in the MVIs that were processed by the Backus-Gilbert method is more reliable.展开更多
This study presents a high-accuracy,all-fber mode division multiplexing(MDM)reconstructive spectrometer(RS).The MDM was achieved by utilizing a custom-designed 3×1 mode-selective photonics lantern to launch disti...This study presents a high-accuracy,all-fber mode division multiplexing(MDM)reconstructive spectrometer(RS).The MDM was achieved by utilizing a custom-designed 3×1 mode-selective photonics lantern to launch distinct spatial modes into the multimode fber(MMF).This facilitated the information transmission by increasing light scattering processes,thereby encoding the optical spectra more comprehensively into speckle patterns.Spectral resolution of 2 pm and the recovery of 2000 spectral channels were accomplished.Compared to methods employing single-mode excitation and two-mode excitation,the three-mode excitation method reduced the recovered error by 88%and 50%respectively.A resolution enhancement approach based on alternating mode modulation was proposed,reaching the MMF limit for the 3 dB bandwidth of the spectral correlation function.The proof-of-concept study can be further extended to encompass diverse programmable mode excitations.It is not only succinct and highly efcient but also well-suited for a variety of high-accuracy,high-resolution spectral measurement scenarios.展开更多
基金This work is supported by the Laoshan National Laboratoryof ScienceandTechnologyFoundation(No.LSKj202203400)the National Natural Science Foundation of China(No.41874146).
文摘Enhancing seismic resolution is a key component in seismic data processing, which plays a valuable role in raising the prospecting accuracy of oil reservoirs. However, in noisy situations, existing resolution enhancement methods are difficult to yield satisfactory processing outcomes for reservoir characterization. To solve this problem, we develop a new approach for simultaneous denoising and resolution enhancement of seismic data based on convolution dictionary learning. First, an elastic convolution dictionary learning algorithm is presented to efficiently learn a convolution dictionary with stronger representation capability from the noisy data to be processed. Specifically, the algorithm introduces the elastic L1/2 norm as a sparsity constraint and employs a steepest gradient descent strategy to efficiently solve the frequency-domain linear system with substantial computational cost in a half-quadratic splitting framework. Then, based on the learned convolution dictionary, a weighted convolutional sparse representation paradigm is designed to encode the noisy data to acquire an optimal sparse approximation of the effective signal. Subsequently, a high-resolution dictionary with a broadband spectrum is constructed by the proposed parameter scaling strategy and matched filtering technique on the basis of atomic spectrum modeling. Finally, the optimal sparse approximation of the effective signal and the constructed high-resolution dictionary are used for data reconstruction to obtain the seismic signal with high resolution and high signal-to-noise ratio. Synthetic and field dataset examples are executed to check the effectiveness and reliability of the developed method. The results indicate that this method has a more competitive performance in seismic applications compared with the conventional deconvolution and spectral whitening methods.
基金Supported by the National Basic Research Program of China under Grant No 2012CB921804the National Natural Science Foundation of China under Grant Nos 61078002,61078020,11104214,61108017,11104216 and 61205112+2 种基金the Research Funds for the Doctoral Program of Higher Education of China under Grant Nos 20110201110006,20110201120005 and 20100201120031the Fundamental Research Funds for the Central Universities of Ministry of Education of China under Grant Nos 2012jdhz05,2011jdhz07,xjj2011083,xjj2011084,xjj2012080 and xjj2013089the China Postdoctoral Science Foundation under Grant No2012M521773
文摘A scheme for fourth-order double-slit ghost interference with a pseudo-thermal light source is proposed. It is shown that not only can the visibility be dramatically enhanced compared to the third-order case, but also higher resolution is demonstrated if we scan two of three reference detectors in opposite directions with the same speed, meanwhile another two in identical directions where the speed of one reference detector is twice the other. The results show that the visibility and resolution improvement of the fourth-order ghost interference fringe can be applied to the Nth-order ghost imaging.
基金the National Key Research and Development Program of China(2021YFF0700300)the National Natural Science Foundation of China(NSFC 62075177,62175112)+1 种基金the Natural Science Foundation of Shaanxi Province(2020JM-193 and 2020JQ-324)the Fundamental Research Funds for the Central Universities(XJS210503,XJS210504,JC2112,and JB210513).
文摘Digital holographic microscopy(DHM),which combines digital holography with optical microscopy,is a wide field,minimally invasive quantitative phase microscopy(QPM)approach for measuring the 3D shape or the inner structure of transparent and translucent samples.However,limited by diffraction,the spatial resolution of conventional DHM is relatively low and incompatible with a wide field of view(FOV)owing to the spatial bandwidth product(SBP)limit of the imaging systems.During the past decades,many efforts have been made to enhance the spatial resolution of DHM while preserving a large FOV by trading with unused degrees of freedom.Illumination modulation techniques,such as oblique illumination,structured illumination,and speckle illumination,can enhance the resolution by adding more high-frequency information to the recording system.Resolution enhancement is also achieved by extrapolation of a hologram or by synthesizing a larger hologram by scanning the sample,the camera,or inserting a diffraction grating between the sample and the camera.For on-chip DHM,spatial resolution is achieved using pixel super-resolution techniques.In this paper,we review various resolution enhancement approaches in DHM and discuss the advantages and disadvantages of these approaches.It is our hope that this review will contribute to advancements in DHM and its practical applications in many fields.
基金supported in part by the Research Grants Council of the Hong Kong Special Administrative Region,China, under project 7131–12Ethe NSFC RGC grant under project N–HKU714–13
文摘In optical scanning holography, one pupil produces a spherical wave and another produces a plane wave. They interfere with each other and result in a fringe pattern for scanning a three-dimensional object. The resolution of the hologram reconstruction is affected by the point spread function(PSF) of the optical system. In this paper, we modulate the PSF by a spiral phase plate, which significantly enhances the lateral and depth resolution. We explain the theory for such resolution enhancement and show simulation results to verify the efficacy of the approach.
基金Project supported by the National Key Research and Development Program of China (Grant No.2018YFB0504302)。
文摘We propose a single-pixel imaging(SPI)method to achieve a higher-resolution image via the Hadamard transform matrix.Unlike traditional SPI schemes,this new method recovers images by correlating single-pixel signals with synchronized transformed patterns of Hadamard bases that are actually projected onto the digital micromirror device.Each transform pattern is obtained through the inverse Fourier transform of the pattern acquired by Gaussian filtering of each Hadamard basis in the frequency domain.The proposed scheme is based on a typical SPI experimental setup and does not add any hardware complexity,enabling the transformation of Hadamard matrices and image reconstruction through data processing alone.Therefore,this approach could be considered as an alternative option for achieving fast SPI in a diffraction-limited imaging system,without the need for additional hardware.
基金supported by the National Natural Science Foundation of China(Nos.62075095 and 62271249)the Key Research and Development Program of Jiangsu Province(No.BE2020030)。
文摘High accuracy and time resolution optical transfer delay(OTD)measurement is highly desired in many multi-path applications,such as optical true-time-delay-based array systems and distributed optical sensors.However,the time resolution is usually limited by the frequency range of the probe signal in frequency-multiplexed OTD measurement techniques.Here,we proposed a time-resolution enhanced OTD measurement method based on incoherent optical frequency domain reflectometry(I-OFDR),where an adaptive filter is designed to suppress the spectral leakage from other paths to break the resolution limitation.A weighted least square(WLS)cost function is first established,and then an iteration approach is used to minimize the cost function.Finally,the appropriate filter parameter is obtained according to the convergence results.In a proof-of-concept experiment,the time-domain response of two optical links with a length difference of 900 ps is successfully estimated by applying a probe signal with a bandwidth of 400 MHz.The time resolution is improved by 2.78times compared to the theoretical resolution limit of the inverse discrete Fourier transform(iDFT)algorithm.In addition,the OTD measurement error is below±0.8 ps.The proposed algorithm provides a novel way to improve the measurement resolution without applying a probe signal with a large bandwidth,avoiding measurement errors induced by the dispersion effect.
文摘We describe a post resolution-enhancement-technique verification method for use in manufacturing data flow. The goal of the method is to verify whether designs function as intended,or more precisely, whether the printed images are consistent with the design intent. The process modeling is described for the model-based verifi cation method. The performance of the method is demonstrated by experiment.
基金Supported by the National Natural Science Foundation of China (NSFC) (No.60772103)China National Key Laboratory of Microwave Imaging Technology Foundation (No.9140C1903050804)
文摘Based on dual-frequencies dual-apertures spaceborne SAR （Synthetic Aperture Radar）, a new SAR system with four receiving channels and two operation modes is presented in this paper, SAR imaging and Moving Target Indication （MTI） are studied in this system. High resolution imaging with wide swath is implemented by the Mode Ⅰ, and MTI is completed by the Mode Ⅱ. High azimuth resolution is achieved by the Displaced Phase Center （DPC） multibeam technique. And the Coherent Accumulation （CA） method, which combines dual channels data of different carrier frequency, is used to enhance the range resolution. For the data of different carrier frequency, the two aperture interferometric processing is executed to implement clutter cancellation, respectively. And the couple of clutter suppressed data are employed to implement Dual Carrier Frequency Conjugate Processing （DCFCP）, then both slow and fast moving targets detection can be completed, followed by moving target imaging. The simulation results show the validity of the signal processing method of this new SAR system.
基金supported by the Brain Korea 21 Program (Information Technology of Seoul National University)
文摘We introduce a phase-only hologram generation method based on an integral imaging, and propose an enhancement method in representable depth interval. The computational integral imaging reconstruction method is modified based on optical flow to obtain depth-slice images for the focused objects only. A phaseonly hologram for＇ multiple plane images is generated using the iterative Fresnel transform algorithm. In addition, a division method in hologram plane is proposed for enhancement in the representable minimum depth interval.
基金supported by Chinese Special Funds for National Basic Research Project of China (Grant No. 2007CB714403)National High Technology Research and Development Program of China (Grant Nos. 2007AA12Z135, 2008AA12Z110)Chinese Academy of Sciences (Grant No. KZCX2-YW-Q10-2)
文摘Microwave radiometers have many applications because of their penetration ability. However, two major problems remain that obstruct the development of microwave research. One factor that limits their commercial application is the relatively low resolution of microwave radiometers. The other is the non-uniform spatial resolution for each frequency of the radiometer. The resolution mismatch becomes a critical consideration when observations at two or more frequencies must be combined. In this paper, we have used the Backus-Gilbert method to solve these two problems, while AMSR-E is chosen as the research object. First, we derived the Backus-Gilbert method in detail. The simulated data were then used to decide the optimum parameters in the Backus-Gilbert method. To enhance the resolution, the Backus-Gilbert method has been applied to the AMSR-E data, which covered the Mexico Gulf and the Amazon River. After resolution was enhanced, detailed information was obtained and compared with visible high resolution data. To match the resolution, the AMSR-E data from the Oklahoma Little Washed were used to compute the Microwave Vegetation Index (MVI), which was developed by J. C. Shi. Compared to the original MVIs, the information contained in the MVIs that were processed by the Backus-Gilbert method is more reliable.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant No.62305391)Hunan Innovative Province Construction Project(No.2019RS3017)Scientifc Fund of National University of Defense Technology(No.22-061).
文摘This study presents a high-accuracy,all-fber mode division multiplexing(MDM)reconstructive spectrometer(RS).The MDM was achieved by utilizing a custom-designed 3×1 mode-selective photonics lantern to launch distinct spatial modes into the multimode fber(MMF).This facilitated the information transmission by increasing light scattering processes,thereby encoding the optical spectra more comprehensively into speckle patterns.Spectral resolution of 2 pm and the recovery of 2000 spectral channels were accomplished.Compared to methods employing single-mode excitation and two-mode excitation,the three-mode excitation method reduced the recovered error by 88%and 50%respectively.A resolution enhancement approach based on alternating mode modulation was proposed,reaching the MMF limit for the 3 dB bandwidth of the spectral correlation function.The proof-of-concept study can be further extended to encompass diverse programmable mode excitations.It is not only succinct and highly efcient but also well-suited for a variety of high-accuracy,high-resolution spectral measurement scenarios.
