Journals > > Topics > Imaging Systems and Image Processing
Imaging Systems and Image Processing|59 Article(s)
High-resolution single-pixel holography for biological specimens
Zhiyong Wang, Yazhen Wang, Yuecheng Shen, Dalong Qi, Yunhua Yao, Lianzhong Deng, Zhenrong Sun, and Shian Zhang
Single-pixel imaging (SPI) is a computational imaging technique that is able to reconstruct high-resolution images using a single-pixel detector. However, most SPI demonstrations have been mainly focused on macroscopic scenes, so their applications to biological specimens are generally limited by constraints in space-bandwidth-time product and spatial resolution. In this work, we further enhance SPI’s imaging capabilities for biological specimens by developing a high-resolution holographic system based on heterodyne holography. Our SPI system achieves a space-bandwidth-time product of 41,667 pixel/s and a lateral resolution of 4–5 μm, which represent state-of-the-art technical indices among reported SPI systems. Importantly, our SPI system enables detailed amplitude imaging with high contrast for stained specimens such as epithelial and esophageal cancer samples, while providing complementary phase imaging for unstained specimens including molecular diagnostic samples and mouse brain tissue slices, revealing subtle refractive index variations. These results highlight SPI’s versatility and establish its potential as a powerful tool for advanced biomedical imaging applications. Single-pixel imaging (SPI) is a computational imaging technique that is able to reconstruct high-resolution images using a single-pixel detector. However, most SPI demonstrations have been mainly focused on macroscopic scenes, so their applications to biological specimens are generally limited by constraints in space-bandwidth-time product and spatial resolution. In this work, we further enhance SPI’s imaging capabilities for biological specimens by developing a high-resolution holographic system based on heterodyne holography. Our SPI system achieves a space-bandwidth-time product of 41,667 pixel/s and a lateral resolution of 4–5 μm, which represent state-of-the-art technical indices among reported SPI systems. Importantly, our SPI system enables detailed amplitude imaging with high contrast for stained specimens such as epithelial and esophageal cancer samples, while providing complementary phase imaging for unstained specimens including molecular diagnostic samples and mouse brain tissue slices, revealing subtle refractive index variations. These results highlight SPI’s versatility and establish its potential as a powerful tool for advanced biomedical imaging applications.
Chinese Optics Letters
- Publication Date: Apr. 17, 2025
- Vol. 23, Issue 4, 041103 (2025)
Compressed sensing reflection matrix optical coherent tomography
Kang Liu, Jia Wu, Jing Cao, Rusheng Zhuo, Kun Li, Xiaoxi Chen, Qiang Zhou, Pinghe Wang, and Guohua Shi
The reflection matrix optical coherence tomography (RM-OCT) method has made significant progress in extending imaging depth within scattering media. However, the current method of measuring the reflection matrix (RM) through uniform sampling results in relatively long data collection time. This study demonstrates that the RM in scattering media exhibits sparsity. Consequently, a compressed sensing (CS)-based technique for measuring the RM is proposed and applied to RM-OCT images. Experimental results show that this method requires less than 50% of the traditional sampling data to recover target information within scattering media, thereby significantly reducing data acquisition time. These findings not only expand the theory of the RM but also provide a more efficient measurement approach. This advancement opens up broader applications for CS techniques in RM-OCT and holds great potential for improving imaging efficiency in scattering media. The reflection matrix optical coherence tomography (RM-OCT) method has made significant progress in extending imaging depth within scattering media. However, the current method of measuring the reflection matrix (RM) through uniform sampling results in relatively long data collection time. This study demonstrates that the RM in scattering media exhibits sparsity. Consequently, a compressed sensing (CS)-based technique for measuring the RM is proposed and applied to RM-OCT images. Experimental results show that this method requires less than 50% of the traditional sampling data to recover target information within scattering media, thereby significantly reducing data acquisition time. These findings not only expand the theory of the RM but also provide a more efficient measurement approach. This advancement opens up broader applications for CS techniques in RM-OCT and holds great potential for improving imaging efficiency in scattering media.
Chinese Optics Letters
- Publication Date: Apr. 11, 2025
- Vol. 23, Issue 4, 041102 (2025)
Feature fusion and variational autoencoder based deep coded aperture design for a CUP-VISAR diagnostic system
Miao Li, Chenyan Wang, Xi Wang, Lingqiang Zhang, Chaorui Chen, Zhaohui Guo, and Xueyin Zhao
In this Letter, a coding aperture design framework is introduced for data sampling of a CUP-VISAR system in laser inertial confinement fusion (ICF) research. It enhances shock wave velocity fringe reconstruction through feature fusion with a convolutional variational auto-encoder (CVAE) network. Simulation and experimental results indicate that, compared to random coding aperture, the proposed coding matrices exhibit superior reconstruction quality, achieving more accurate fringe pattern reconstruction and resolving coding information aliasing. In the experiments, the system signal-to-noise ratio (SNR) and reconstruction quality can be improved by increasing the light transmittance of the encoding matrix. This framework aids in diagnosing ICF in challenging experimental settings. In this Letter, a coding aperture design framework is introduced for data sampling of a CUP-VISAR system in laser inertial confinement fusion (ICF) research. It enhances shock wave velocity fringe reconstruction through feature fusion with a convolutional variational auto-encoder (CVAE) network. Simulation and experimental results indicate that, compared to random coding aperture, the proposed coding matrices exhibit superior reconstruction quality, achieving more accurate fringe pattern reconstruction and resolving coding information aliasing. In the experiments, the system signal-to-noise ratio (SNR) and reconstruction quality can be improved by increasing the light transmittance of the encoding matrix. This framework aids in diagnosing ICF in challenging experimental settings.
Chinese Optics Letters
- Publication Date: Apr. 10, 2025
- Vol. 23, Issue 4, 041101 (2025)
Single frame memory-effect based bispectral analysis for high-resolution imaging through scattering media
Pan Zhang, Yuanyuan Liu, and Qiwen Zhan
Imaging through scattering media remains a formidable challenge in optical imaging. Exploiting the memory effect presents new opportunities for non-invasive imaging through the scattering medium by leveraging speckle correlations. Traditional speckle correlation imaging often utilizes a random phase as the initial phase, leading to challenges such as convergence to incorrect local minima and the inability to resolve ambiguities in object orientation. Here, a novel method for high-quality reconstruction of single-shot scattering imaging is proposed. By employing the initial phase obtained from bispectral analysis in the subsequent phase retrieval algorithm, the convergence and accuracy of the reconstruction process are notably improved. Furthermore, a robust search technique based on an image clarity evaluation function successfully determines the optimal reconstruction size. The study demonstrates that the proposed method can obtain high-quality reconstructed images compared with the existing scattering imaging approaches. This innovative approach to non-invasive single-shot imaging through strongly scattering media shows potential for applications in scenarios involving moving objects or dynamic scattering imaging scenes. Imaging through scattering media remains a formidable challenge in optical imaging. Exploiting the memory effect presents new opportunities for non-invasive imaging through the scattering medium by leveraging speckle correlations. Traditional speckle correlation imaging often utilizes a random phase as the initial phase, leading to challenges such as convergence to incorrect local minima and the inability to resolve ambiguities in object orientation. Here, a novel method for high-quality reconstruction of single-shot scattering imaging is proposed. By employing the initial phase obtained from bispectral analysis in the subsequent phase retrieval algorithm, the convergence and accuracy of the reconstruction process are notably improved. Furthermore, a robust search technique based on an image clarity evaluation function successfully determines the optimal reconstruction size. The study demonstrates that the proposed method can obtain high-quality reconstructed images compared with the existing scattering imaging approaches. This innovative approach to non-invasive single-shot imaging through strongly scattering media shows potential for applications in scenarios involving moving objects or dynamic scattering imaging scenes.
Chinese Optics Letters
- Publication Date: Mar. 25, 2025
- Vol. 23, Issue 3, 031103 (2025)
Robust two-step Fourier single-pixel imaging
Rui Sun, Yi Ding, Jingjing Cheng, Jian Pan, Jiekai Zhuo, and Xiaoqun Yuan
Existing two-step Fourier single-pixel imaging (FSPI) suffers from low noise-robustness, and three-step FSPI and four-step FSPI improve the noise-robustness but at the cost of more measurements. In this Letter, we propose a method to improve the noise-robustness of two-step FSPI without additional illumination patterns or measurements. In the proposed method, the measurements from base patterns are replaced by the average values of the measurement from two sets of phase-shift patterns. Thus, the imaging degradation caused by the noise in the measurements from base patterns can be avoided, and more reliable Fourier spectral coefficients are obtained. The imaging quality of the proposed robust two-step FSPI is similar to those of three-step FSPI and four-step FSPI. Simulations and experimental results validate the effectiveness of the proposed method. Existing two-step Fourier single-pixel imaging (FSPI) suffers from low noise-robustness, and three-step FSPI and four-step FSPI improve the noise-robustness but at the cost of more measurements. In this Letter, we propose a method to improve the noise-robustness of two-step FSPI without additional illumination patterns or measurements. In the proposed method, the measurements from base patterns are replaced by the average values of the measurement from two sets of phase-shift patterns. Thus, the imaging degradation caused by the noise in the measurements from base patterns can be avoided, and more reliable Fourier spectral coefficients are obtained. The imaging quality of the proposed robust two-step FSPI is similar to those of three-step FSPI and four-step FSPI. Simulations and experimental results validate the effectiveness of the proposed method.
Chinese Optics Letters
- Publication Date: Mar. 26, 2025
- Vol. 23, Issue 3, 031102 (2025)
Single-shot double-pulse range-gated 3D imaging
Junquan Sun, Yongkai Yin, Hua Fan, Xiaolei Zhang, and Baoqing Sun
Range-gated imaging has the advantages of long imaging distance, high signal-to-noise ratio, and good environmental adaptability. However, conventional range-gated imaging utilizes a single laser pulse illumination modality, which can only resolve a single depth of ranging in one shot. Three-dimensional (3D) imaging has to be obtained from multiple shots, which limits its real-time performance. Here, an approach of range-gated imaging using a specific double-pulse sequence is proposed to overcome this limitation. With the help of a calibrated double-pulse range-intensity profile, the depth of static targets can be calculated from the measurement of a single shot. Moreover, the double-pulse approach is beneficial for real-time depth estimation of dynamic targets. Experimental results indicate that, compared to the conventional approach, the depth of field and depth resolution are increased by 1.36 and 2.20 times, respectively. It is believed that the proposed double-pulse approach provides a potential new paradigm for range-gated 3D imaging. Range-gated imaging has the advantages of long imaging distance, high signal-to-noise ratio, and good environmental adaptability. However, conventional range-gated imaging utilizes a single laser pulse illumination modality, which can only resolve a single depth of ranging in one shot. Three-dimensional (3D) imaging has to be obtained from multiple shots, which limits its real-time performance. Here, an approach of range-gated imaging using a specific double-pulse sequence is proposed to overcome this limitation. With the help of a calibrated double-pulse range-intensity profile, the depth of static targets can be calculated from the measurement of a single shot. Moreover, the double-pulse approach is beneficial for real-time depth estimation of dynamic targets. Experimental results indicate that, compared to the conventional approach, the depth of field and depth resolution are increased by 1.36 and 2.20 times, respectively. It is believed that the proposed double-pulse approach provides a potential new paradigm for range-gated 3D imaging.
Chinese Optics Letters
- Publication Date: Mar. 20, 2025
- Vol. 23, Issue 3, 031101 (2025)
In vivo whole brain photoacoustic microscopy through a transparent ultrasound transducer
Chen Liang, Junwei Wu, Hangbing Peng, Lijun Deng, Yiqin Lin, Zhongwen Cheng, Lüming Zeng, and Xuanrong Ji
Brain imaging techniques provide in vivo insight into structural and functional phenotypes that are physiologically and clinically relevant. However, most existing brain imaging techniques suffer from balancing trade-offs among the temporal and spatial resolutions as well as the field of view (FOV). Here, we proposed a high-resolution photoacoustic microscopy (PAM) system based on a transparent ultrasound transducer (TUT). The system not only retains the advantage of the fast imaging speed of pure optical scanning but also has an imaging FOV of up to 20 mm × 20 mm, which can easily enable rapid imaging of the whole mouse brain in vivo. Based on experimental validation of brain injury, glioma, and cerebral hemorrhage in mice, the system has the capability to visualize the vascular structure and hemodynamic changes in the cerebral cortex. TUT-based PAM provides an important research tool for rapid multi-parametric brain imaging in small animals, providing a solid foundation for the study of brain diseases. Brain imaging techniques provide in vivo insight into structural and functional phenotypes that are physiologically and clinically relevant. However, most existing brain imaging techniques suffer from balancing trade-offs among the temporal and spatial resolutions as well as the field of view (FOV). Here, we proposed a high-resolution photoacoustic microscopy (PAM) system based on a transparent ultrasound transducer (TUT). The system not only retains the advantage of the fast imaging speed of pure optical scanning but also has an imaging FOV of up to 20 mm × 20 mm, which can easily enable rapid imaging of the whole mouse brain in vivo. Based on experimental validation of brain injury, glioma, and cerebral hemorrhage in mice, the system has the capability to visualize the vascular structure and hemodynamic changes in the cerebral cortex. TUT-based PAM provides an important research tool for rapid multi-parametric brain imaging in small animals, providing a solid foundation for the study of brain diseases.
Chinese Optics Letters
- Publication Date: Mar. 05, 2025
- Vol. 23, Issue 2, 021102 (2025)
Phase unwrapping by a multi-level grid method for moiré fringes
Yunyun Chen, Chengxing He, Weihao Cheng, and Wenzhuo Xie
Phase unwrapping is a crucial process in the field of optical measurement, and the effectiveness of unwrapping directly affects the accuracy of final results. This study proposes a multi-level grid method that can efficiently achieve phase unwrapping. First, the phase image of the package to be processed is divided into small grids, and each grid is unwrapped in multiple directions. Then, a level-by-level coarse-graining mesh method is employed to eliminate the new data “faults” generated from the previous level of grid processing. Finally, the true phase results are obtained by iterating to the coarsest grid through the unwrapping process. In order to verify the effectiveness and superiority of the proposed method, a numerical simulation is first applied. Further, three typical flow fields are selected for experiments, and the results are compared with flood-fill and multi-grid methods for accuracy and efficiency. The proposed method obtains true phase information in just 0.5 s; moreover, it offers more flexibility in threshold selection compared to the flood-fill and region-growing methods. In summary, the proposed method can solve the phase unwrapping problems for moiré fringes, which could provide possibilities for the intelligent development of moiré deflection tomography. Phase unwrapping is a crucial process in the field of optical measurement, and the effectiveness of unwrapping directly affects the accuracy of final results. This study proposes a multi-level grid method that can efficiently achieve phase unwrapping. First, the phase image of the package to be processed is divided into small grids, and each grid is unwrapped in multiple directions. Then, a level-by-level coarse-graining mesh method is employed to eliminate the new data “faults” generated from the previous level of grid processing. Finally, the true phase results are obtained by iterating to the coarsest grid through the unwrapping process. In order to verify the effectiveness and superiority of the proposed method, a numerical simulation is first applied. Further, three typical flow fields are selected for experiments, and the results are compared with flood-fill and multi-grid methods for accuracy and efficiency. The proposed method obtains true phase information in just 0.5 s; moreover, it offers more flexibility in threshold selection compared to the flood-fill and region-growing methods. In summary, the proposed method can solve the phase unwrapping problems for moiré fringes, which could provide possibilities for the intelligent development of moiré deflection tomography.
Chinese Optics Letters
- Publication Date: Mar. 10, 2025
- Vol. 23, Issue 2, 021101 (2025)
Computational ghost holography with Laguerre-Gaussian modes|On the Cover
Liyuan Xu, Zizhuo Lin, Ruijian Li, Yin Wang, Tong Liu, Zhengliang Liu, Linlin Chen, and Yuan Ren
Computational ghost holography is a single-pixel imaging technique that has garnered significant attention for its ability to simultaneously acquire both the amplitude and phase images of objects. Typically, single-pixel imaging schemes rely on real-value orthogonal bases, such as Hadamard, Fourier, and wavelet bases. In this Letter, we introduce a novel computational ghost holography scheme with Laguerre–Gaussian (LG) modes as the complex orthogonal basis. It is different from the traditional methods that require the number of imaging pixels to exactly match the number of modulation modes. Our method utilizes 4128 distinct LG modes for illumination. By employing the second-order correlation (SOC) and TVAL3 compressed sensing (CS) algorithms, we have successfully reconstructed the amplitude and phase images of complex objects, and the actual spatial resolution obtained by the experiments is about 70 µm. Due to the symmetry of the LG modes, objects with rotational symmetry can be recognized and imaged using fewer modes. The difference between bucket detection and zero-frequency detection is analyzed theoretically and verified experimentally. Moreover, in the process of object reconstruction, the advanced image processing function can be seamlessly integrated via the preprocessing of the LG modes. As such, it may find a wide range of applications in biomedical diagnostics and target recognition. Computational ghost holography is a single-pixel imaging technique that has garnered significant attention for its ability to simultaneously acquire both the amplitude and phase images of objects. Typically, single-pixel imaging schemes rely on real-value orthogonal bases, such as Hadamard, Fourier, and wavelet bases. In this Letter, we introduce a novel computational ghost holography scheme with Laguerre–Gaussian (LG) modes as the complex orthogonal basis. It is different from the traditional methods that require the number of imaging pixels to exactly match the number of modulation modes. Our method utilizes 4128 distinct LG modes for illumination. By employing the second-order correlation (SOC) and TVAL3 compressed sensing (CS) algorithms, we have successfully reconstructed the amplitude and phase images of complex objects, and the actual spatial resolution obtained by the experiments is about 70 µm. Due to the symmetry of the LG modes, objects with rotational symmetry can be recognized and imaged using fewer modes. The difference between bucket detection and zero-frequency detection is analyzed theoretically and verified experimentally. Moreover, in the process of object reconstruction, the advanced image processing function can be seamlessly integrated via the preprocessing of the LG modes. As such, it may find a wide range of applications in biomedical diagnostics and target recognition.
Chinese Optics Letters
- Publication Date: Jan. 21, 2025
- Vol. 23, Issue 1, 011101 (2025)
Arbitrary n-step phase-shifting Fourier single-pixel imaging
Zongguo Li, Biao Wang, Zhandong Liu, Kai Xu, Jinyi Jia, and Hongguo Li
In this Letter, we innovatively present general analytical expressions for arbitrary n-step phase-shifting Fourier single-pixel imaging (FSI). We also design experiments capable of implementing arbitrary n-step phase-shifting FSI and compare the experimental results, including the image quality, for 3- to 6-step phase-shifting cases without loss of generality. These results suggest that, compared to the 4-step method, these FSI approaches with a larger number of steps exhibit enhanced robustness against noise while ensuring no increase in data-acquisition time. These approaches provide us with more strategies to perform FSI for different steps, which could offer guidance in balancing the tradeoff between the image quality and the number of steps encountered in the application of FSI. In this Letter, we innovatively present general analytical expressions for arbitrary n-step phase-shifting Fourier single-pixel imaging (FSI). We also design experiments capable of implementing arbitrary n-step phase-shifting FSI and compare the experimental results, including the image quality, for 3- to 6-step phase-shifting cases without loss of generality. These results suggest that, compared to the 4-step method, these FSI approaches with a larger number of steps exhibit enhanced robustness against noise while ensuring no increase in data-acquisition time. These approaches provide us with more strategies to perform FSI for different steps, which could offer guidance in balancing the tradeoff between the image quality and the number of steps encountered in the application of FSI.
Chinese Optics Letters
- Publication Date: Aug. 21, 2024
- Vol. 22, Issue 8, 081101 (2024)
Topics
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20