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Optical Imaging and Sensing

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Sensing and Imaging".

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 7755

Special Issue Editor


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Guest Editor
School of Physics, Xi’an Jiaotong University, Xi'an 710049, China
Interests: optical imaging; optical probes; biomedical applications; multiphoton fluorescence imaging

Special Issue Information

Dear Colleagues,

Optical imaging and sensing technologies are fundamental tools for chemical analyte detection and biological discovery. Fluorescence-based probes are widely used as sensors to detect and monitor various chemical and biological agents and activities due to their excellent selectivity, stability, reliability, and sensitivity. Fluorescent sensors can be classified into genetically encoded proteins, organic fluorophores, inorganic probes, and so on. In particular, fluorescent nanoparticles (e.g., gold- and carbon-based nanomaterials, quantum dots, upconverting nanoparticles, and metal-organic frameworks) have shown excellent optical properties and functionalities for optical imaging and sensing. In recent years, with the development of advanced optical imaging technologies such as multiphoton fluorescence imaging, super-resolution imaging, and near-infrared-II fluorescence imaging, various fluorescent sensors have been developed and applied for sensing metal ions, amino acids, enzymes, toxins, biomarkers, neurotransmitters, proteins, antibodies, drugs, nucleic acids, gaseous species, and so on through optical imaging in vitro and in vivo. This Special Issue is addressed to all types of fluorescence-based sensors designed for chemical and biological imaging and sensing.

Prof. Dr. Shaowei Wang
Guest Editor

Manuscript Submission Information

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Keywords

  • fluorescence-based sensors
  • fluorescent probes
  • optical imaging
  • fluorescence imaging
  • biosensors
  • chemical sensors
  • reactivity-based probes
  • optical probes

Published Papers (4 papers)

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Research

15 pages, 4141 KiB  
Article
Automatic Suppression Method for Water Surface Glints Using a Division of Focal Plane Visible Polarimeter
by Meishu Wang, Su Qiu, Weiqi Jin and Jie Yang
Sensors 2023, 23(17), 7446; https://doi.org/10.3390/s23177446 - 26 Aug 2023
Cited by 2 | Viewed by 952
Abstract
To address the problem of water surface detection imaging equipment being susceptible to water surface glints, this study demonstrates a method called De-Glints for suppressing glints and obtaining clear underwater images using a division of focal plane (DoFP) polarimeter. Based on the principle [...] Read more.
To address the problem of water surface detection imaging equipment being susceptible to water surface glints, this study demonstrates a method called De-Glints for suppressing glints and obtaining clear underwater images using a division of focal plane (DoFP) polarimeter. Based on the principle of polarization imaging, the best polarization angle and the image corresponding to the minimal average gray level of each pixel are calculated. To evaluate the improvement in image quality, the index E was designed. The results of indoor and outdoor experiments show that the error of the angle calculation of this method is within 10%, and the minimum error is only 3%. The E index is positively improved and can be relatively improved by 8.00 under the interference of strong outdoor glints, and the method proposed in this paper shows a good adaptive ability to the dynamic scene. Full article
(This article belongs to the Special Issue Optical Imaging and Sensing)
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12 pages, 3090 KiB  
Article
Underwater Target Detection Utilizing Polarization Image Fusion Algorithm Based on Unsupervised Learning and Attention Mechanism
by Haoyuan Cheng, Deqing Zhang, Jinchi Zhu, Hao Yu and Jinkui Chu
Sensors 2023, 23(12), 5594; https://doi.org/10.3390/s23125594 - 15 Jun 2023
Cited by 6 | Viewed by 1746
Abstract
Since light propagation in water bodies is subject to absorption and scattering effects, underwater images using only conventional intensity cameras will suffer from low brightness, blurred images, and loss of details. In this paper, a deep fusion network is applied to underwater polarization [...] Read more.
Since light propagation in water bodies is subject to absorption and scattering effects, underwater images using only conventional intensity cameras will suffer from low brightness, blurred images, and loss of details. In this paper, a deep fusion network is applied to underwater polarization images; that is, the underwater polarization images are fused with intensity images using the deep learning method. To construct a training dataset, we establish an experimental setup to obtain underwater polarization images and perform appropriate transformations to expand the dataset. Next, an end-to-end learning framework based on unsupervised learning and guided by an attention mechanism is constructed for fusing polarization and light intensity images. The loss function and weight parameters are elaborated. The produced dataset is used to train the network under different loss weight parameters, and the fused images are evaluated based on different image evaluation metrics. The results show that the fused underwater images are more detailed. Compared with light intensity images, the information entropy and standard deviation of the proposed method increase by 24.48% and 139%. The image processing results are better than other fusion-based methods. In addition, the improved U-net network structure is used to extract features for image segmentation. The results show that the target segmentation based on the proposed method is feasible under turbid water. The proposed method does not require manual adjustment of weight parameters, has faster operation speed, and has strong robustness and self-adaptability, which is important for research in vision fields, such as ocean detection and underwater target recognition. Full article
(This article belongs to the Special Issue Optical Imaging and Sensing)
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14 pages, 4439 KiB  
Article
Freeform Wide Field-of-View Spaceborne Imaging Telescope: From Design to Demonstrator
by Luca Schifano, Michael Vervaeke, Dries Rosseel, Jef Verbaenen, Hugo Thienpont, Steven Dewitte, Francis Berghmans and Lien Smeesters
Sensors 2022, 22(21), 8233; https://doi.org/10.3390/s22218233 - 27 Oct 2022
Cited by 6 | Viewed by 2492
Abstract
Wide field-of-view imaging optics offer a huge potential for space-based Earth observation enabling the capture of global data. Reflective imaging telescopes are often favored, as they do not show chromatic aberrations and are less susceptible to radiation darkening than their refractive counterparts. However, [...] Read more.
Wide field-of-view imaging optics offer a huge potential for space-based Earth observation enabling the capture of global data. Reflective imaging telescopes are often favored, as they do not show chromatic aberrations and are less susceptible to radiation darkening than their refractive counterparts. However, the main drawback of reflective telescopes is that they are limited with respect to field-of-view while featuring large dimensions. We propose the use of freeform optics to maximize the field of view while maintaining diffraction-limited image quality and minimizing system dimensions. In this paper, we present a novel freeform wide field-of-view reflective telescope, starting from the optical design, and continuing to tolerancing analysis and manufacture, towards a proof-of-concept demonstrator. The novel telescope features a full field-of-view of 120° while showing an exceptional spatial resolution of 2.6 km and fitting within 1 CubeSat unit. To the best of our knowledge, this is the widest field-of-view that has ever been realized for a space-based telescope, nearly reaching Earth observation from limb to limb from an altitude of about 700 km. We hope this design paves the way for future space missions enabling improved Earth observation and leading to enhanced monitoring of climate and climate change. Full article
(This article belongs to the Special Issue Optical Imaging and Sensing)
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16 pages, 7052 KiB  
Article
Equivalent Calibration Method Based on a Blackbody Baffle Substitution for a Large External Surface-Source Blackbody
by Xinyu Pang, Yi Yu, Zhou Li, Zhiyuan Sun, Chun Li and Guoqing Yang
Sensors 2022, 22(15), 5844; https://doi.org/10.3390/s22155844 - 4 Aug 2022
Cited by 2 | Viewed by 1788
Abstract
Highly accurate measurements of infrared systems cannot be achieved without precise radiometric calibrations. In order to correctly interpret and process infrared images and monitor the performance of infrared cameras, their radiometric calibration is also required periodically. In this paper, an equivalent calibration method [...] Read more.
Highly accurate measurements of infrared systems cannot be achieved without precise radiometric calibrations. In order to correctly interpret and process infrared images and monitor the performance of infrared cameras, their radiometric calibration is also required periodically. In this paper, an equivalent calibration method is proposed based on an internal blackbody baffle. It is used for the replacement of a large surface-source blackbody covering the aperture for the field calibration of large-aperture equipment. Subsequently, the expressions of the equivalent calibration conversion function (ECCF) are derived based on the grayscale response of the camera and the calibration models of the two methods, and experimental measurements and fits are performed using a cooled mid-wave infrared camera. The results show that the measured functional form is consistent with the physical meaning. Moreover, in the target imaging experiments, the results of the inversion using the equivalent calibration conversion function and the results of the direct calibration of the external blackbody are largely consistent with the average error of 0.198% between the two, and the maximum error is within 1%. The maximum error between the inversion result of radiation brightness and the actual value of the target is 6.29%, and the accuracy fully meets the radiometric measurement requirements. Full article
(This article belongs to the Special Issue Optical Imaging and Sensing)
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