Lensless fiber endoscopes are of great importance for keyhole imaging. Coherent fiber bundles (CFB) can be used in endoscopes as remote phased arrays to capture images. One challenge is to image at high speed while co...
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Lensless fiber endoscopes are of great importance for keyhole imaging. Coherent fiber bundles (CFB) can be used in endoscopes as remote phased arrays to capture images. One challenge is to image at high speed while correcting aberrations induced by the CFB. We propose the combination of digital optical phase conjugation, using a spatial light modulator, with fast scanning, for which a 2D galvo scanner and an adaptive lens are employed. We achieve the transmission of laser and image scanning through the CFB. Video-rate imaging at 20 Hz in 2D with subcellular resolution is demonstrated in 3D with 1 Hz. The sub-millimeter-diameter scanning endoscope has a great potential in biomedicine, for manipulation, e.g., in optogenetics, as well as in imaging. (C) 2020 Optical Society of America
Single particle interferometric reflectance (SPIR) microscopy has been studied as a powerful imaging platform for label-free and highly sensitive biological nanoparticle detection and characterization. SPIR's inte...
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Single particle interferometric reflectance (SPIR) microscopy has been studied as a powerful imaging platform for label-free and highly sensitive biological nanoparticle detection and characterization. SPIR's interferometric nature yields a unique 3D defocus intensity profile of the nanoparticles over a large field of view. Here, we utilize this defocus information to recover high signal-to-noise ratio nanoparticle images with a computationally and memory efficient reconstruction framework. Our direct inversion approach recovers this image from a 3D defocus intensity stack using the vectorial-optics-based forward model developed for sub-diffraction-limited dielectric nanoparticles captured on a layered substrate. We demonstrate proof-of-concept experiments on silica beads with a 50 nm nominal diameter. (C) 2020 Optical Society of America
Understanding turbulence effects on laser beam propagation is critical to the emerging design, study, and test of many long-range free space optical (FSO) communication and directed energy systems. Conventional studie...
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Understanding turbulence effects on laser beam propagation is critical to the emerging design, study, and test of many long-range free space optical (FSO) communication and directed energy systems. Conventional studies make the prevalent assumption of isotropic turbulence, while more recent results suggest anisotropic turbulence for atmospheric channels within a few meters elevation above the ground. As countless FSO systems have been and continue to be deployed in such channels, analysis of anisotropic modelings has become one of the fastest growing areas in FSO research. This in turn motivates new tools that can distinguish anisotropic characteristics to improve both modeling accuracy and physical interpretations. Wavefront sensors such as Shack-Hartmann sensors, interferometers, and plenoptic sensors have been devised and used in experiments;however, they all require rigid alignments that lack resilience against temperature gradient buildup and beam wander. We find that by using a light field camera (LFC) that extracts perturbation of individual light rays, the wave structure function of turbulence can be retrieved with high reliability. Furthermore, we find through experiments that the outer scales of near-ground turbulence tend to be a magnitude smaller than conventional theoretical assumptions, agreeing with new findings by others but being absent in current theoretical modelings. As a result, we believe that the LFC is an ideal candidate in the frontier of turbulence research;it is both commercially available and easy to adapt to turbulence experiments. (C) 2020 Optical Society of America
Projector calibration is one of the most essential steps for structured light systems. Some methods have high precision but require a complicated calibration procedure, such as the method based on phase-shifting. Othe...
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Projector calibration is one of the most essential steps for structured light systems. Some methods have high precision but require a complicated calibration procedure, such as the method based on phase-shifting. Other methods take advantage of simple implementation but cannot meet the accuracy requirement, for example, the method based on homography. In this paper, we proposed a compensation method for flexible and accurate projector calibration. To make the calibration procedure easy to operate, the homographic matrix between the projector and camera is established through feature points projected. Then, the 2D image points compensation method based on the re-projection error iteration algorithm was carried out, and a modified bundle adjustment (BA) algorithm is put forward to refine the calibration parameters of the system. Finally, the feature point reconstruction experiment is implemented to verify the high flexibility and accuracy performance of the proposed method. (c) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
In this paper, we proposed a sub-pixel measurement algorithm based on intensity integration threshold (IIT). The proposed method can localize the sub-pixel edges in an inexpensive way by calculating the integration of...
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In this paper, we proposed a sub-pixel measurement algorithm based on intensity integration threshold (IIT). The proposed method can localize the sub-pixel edges in an inexpensive way by calculating the integration of the intensity across the edge and finding the point where the integration reaches the threshold. Comparative tests show our method realized better efficiency and robustness in practical applications than other state-of-the-art algorithms. (c) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Laser speckle contrast imaging (LSCI) can be used to observe dynamic changes in the tissue microcirculation in vivo according to the dynamic interaction between red blood cells and coherent light. In this study, a dua...
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Laser speckle contrast imaging (LSCI) can be used to observe dynamic changes in the tissue microcirculation in vivo according to the dynamic interaction between red blood cells and coherent light. In this study, a dual-wavelength LSCI system based on a microscope was developed for in vivo observation of the microvascular pattern and measurement of the blood flow change in the animal model. Additionally, based on the dual-wavelength setup, including 635 and 855 nm wavelengths, the oxygenation of biological tissue was evaluated. Finally, the developed LSCI microscope was implemented for the studies of tissue microcirculation. The results indicate that the developed LSCI microscope could be a potential tool for in vivo observation of the tissue microcirculation and quantitative evaluation of hemodynamics in animal experiments. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Practical stellar interferometry for space domain awareness is challenged by the relative motions of orbital objects and telescope arrays that require array phasing using guide stars. Anorbital object's image sens...
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Practical stellar interferometry for space domain awareness is challenged by the relative motions of orbital objects and telescope arrays that require array phasing using guide stars. Anorbital object's image sensitivity to the location and brightness of the guide star is problematic, possibly resulting in a degraded resolution or loss of image content when both objects fall within the interferometer's field of view. We characterized an orbital object's visibility using visibility contrast to noise ratios (CNR Delta v) as a performance metric for orbital object image quality. Experimental validations included orbital object visibility measurements for dual binary pinholes that were scaled in size and brightness individually to match expected interferometer data collection scenarios. We show agreement in CNR Delta v results, indicating resolvable orbital object signals during periods of collection when signal contributions from both the orbital object and guide star are present. Expanding presented results to imaging interferometers, we discuss how dual object imaging could degrade performance under the scenarios examined. (C) 2021 Optical Society of America
In recent, performances of smartphones are highly developed and they can acquire high resolution image with high framerates. The objective of this study is the development of smartphone-based laryngoscope to reduce th...
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ISBN:
(数字)9781943580767
ISBN:
(纸本)9781943580767
In recent, performances of smartphones are highly developed and they can acquire high resolution image with high framerates. The objective of this study is the development of smartphone-based laryngoscope to reduce the cost of device and demonstrate possibility of highspeed vocal cord imaging by utilizing high performance smartphone camera. We designed customized smartphone adapter for combining clinical laryngoscope and Samsung smartphone. By attaching conventional clinical probes into our customized smartphone adaptor, the high- speed vocal cord endoscopic images were acquired. We could confirm the high-speed digital images of 940fps were acquired from 5 healthy volunteers as a preliminary study. (C) 2020 The Author(s)
For the first time, we demonstrate 40-m range detection and 3D depth scan up to 20 m using a silicon-photonic optical phased array with integrated amplifiers, promising a high-performance solid-state light-detection a...
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ISBN:
(数字)9781943580767
ISBN:
(纸本)9781943580767
For the first time, we demonstrate 40-m range detection and 3D depth scan up to 20 m using a silicon-photonic optical phased array with integrated amplifiers, promising a high-performance solid-state light-detection and ranging (LiDAR) system. (c) 2020 The Author(s)
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