Wide Field Of View Research Articles

Design of a high-speed circular polarization converter with a large field of view and wavelength range.

A high-speed circular polarization converter (CPC) with a wide field of view (FOV) and wavelength range is designed and fabricated in this paper. The multi-waveplate combined structure is applied to constitute the basic configuration of the CPC for broadening the wavelength range. An electrically suppressed helix ferroelectric liquid crystal (ESHFLC) material with fast response is used as a medium for dynamic polarization operation. The compensation films are used to expand the FOV by attaching to the configuration. The simulation results demonstrate that the optimized CPC structure can achieve over 97% orthogonal circular polarization conversion efficiency in 300 nm bandwidth at a 90° viewing cone for both working states. Finally, we have experiments and the results show well consistency with the theoretical results.

High-energy X-ray micro-laminography to visualize microstructures in dense planar objects.

High-energy X-ray micro-laminography has been developed to observe inner- and near-surface structures in dense planar objects that are not suitable for observation by X-ray micro-tomography. A multilayer-monochromator-based high-intensity X-ray beam with energy of 110 keV was used for high-energy and high-resolution laminographic observations. As a demonstration of high-energy X-ray micro-laminography for observing dense planar objects, a compressed fossil cockroach on a planar matrix surface was analyzed with effective pixel sizes of 12.4 µm and 4.22 µm for wide field of view and high-resolution observations, respectively. In this analysis, the near-surface structure was clearly observed without undesired X-ray refraction-based artifacts from outside of the region of interest, a problem typical in tomographic observations. Another demonstration visualized fossil inclusions in a planar matrix. Micro-scale features of a gastropod shell and micro-fossil inclusions in the surrounding matrix were clearly visualized. When observing local structures in the dense planar object with X-ray micro-laminography, the penetrating path length in the surrounding matrix can be shortened. This is a significant advantage of X-ray micro-laminography where desired signals generated at the region of interest including optimal X-ray refraction effectively contribute to image formation without being disturbed by undesired interactions in the thick and dense surrounding matrix. Therefore, X-ray micro-laminography allows recognition of the local fine structures and slight difference in the image contrast of planar objects undetectable in a tomographic observation.

Target Detection Framework for Lobster Eye X-Ray Telescopes with Machine-learning Algorithms

Lobster eye telescopes are ideal monitors to detect X-ray transients because they could observe celestial objects over a wide field of view in the X-ray band. However, images obtained by lobster eye telescopes are modified by their unique point-spread functions, making it hard to design a high-efficiency target detection algorithm. In this paper, we integrate several machine-learning algorithms to build a target detection framework for data obtained by lobster eye telescopes. Our framework would first generate two 2D images with different pixel scales according to positions of photons on the detector. Then, an algorithm based on morphological operations and two neural networks would be used to detect candidates of celestial objects with different flux from these 2D images. Finally, a random forest algorithm will be used to pick up final detection results from candidates obtained by previous steps. Tested with simulated data of the Wide-field X-ray Telescope on board the Einstein Probe, our detection framework could achieve over 94% purity and over 90% completeness for targets with flux more than 3 mcrab (9.6 × 10−11 erg cm−2 s−1) and more than 94% purity and moderate completeness for targets with lower flux at acceptable time cost. The framework proposed in this paper could be used as references for data processing methods developed for other lobster eye X-ray telescopes.

High-Speed Imaging Receiver Design for 6G Optical Wireless Communications: A Rate-FOV Trade-Off

The design of a compact high-speed and wide field of view (FOV) receiver is challenging due to the presence of two well-known trade-offs. The first one is the area-bandwidth trade-off of photodetectors (PDs) and the second one is the gain-FOV trade-off due to the use of optics. The combined effects of these two trade-offs imply that the achievable data rate of an imaging optical receiver is limited by its FOV, i.e., a rate-FOV trade-off. In this paper, we propose an imaging receiver design in the form of an array of (PD) arrays. To control the area-bandwidth trade-off, small PDs are used in an array of arrays structure instead of a single large PD. Moreover, to achieve a reasonable receiver FOV, we use an array of focusing lenses that focus the light individually on each inner PD array. The proposed array of arrays structure provides an effective method to control both gain-FOV trade-off (via an array of lenses) and area-bandwidth trade-off (via arrays of small PDs). We first derive a tractable analytical model for the signal-to-noise ratio (SNR) of an array of PDs that is equipped with a focusing lens assuming maximum ratio combining (MRC). Then, we extend the model to the proposed array of arrays structure and the accuracy of the analytical model is verified based on several Optic Studio-based simulations. Next, we formulate an optimization problem to maximize the achievable data rate of the imaging receiver subject to a minimum required FOV. The optimization problem is solved for two commonly used modulation techniques, namely, on-off keying (OOK) and direct current (DC) biased optical orthogonal frequency division multiplexing (DCO-OFDM) with variable rate quadrature amplitude modulation (QAM). Our results show the limits of high speed wide-FOV imaging receivers that can support mobility. For example, it is demonstrated that a data rate of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 24$ </tex-math></inline-formula> Gbps with a FOV of 15° is achievable using OOK with a total receiver size of 2 cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\!\times \!\,\,2$ </tex-math></inline-formula> cm.

The Crystal Eye X and gamma-ray detector for space missions

Crystal Eye idea comes from the analysis of two gravitational waves events: GW170817 and GW190425. Both events were referred to neutron star mergers. In the first case Fermi-GBM and INTEGRAL claimed the detection of a short Gamma Ray Burst (GRB 170817A) and in order to follow up and target the GW electromagnetic counterparts, a huge effort has been made by other satellites and ground-based experiments. In the second case, only INTEGRAL claimed the detection of a faint GRB (GRB 190425) while Fermi satellite was in Earth occultation. Crystal Eye is a space-based X and γ ray all-sky monitor sensitive in the 10 keV - 30 MeV energy range. In its baseline configuration, it consists of a hemisphere, made by 112 pixels, with a wide (about 6 sr) field of view (FOV), a full sky coverage and a very large effective area (6 times Fermi-GBM at 1 MeV) in the energy range of interest. Given the pixel structure – a two-layer crystal scintillator and a plastic scintillator veto layer – and the hemispherical design, Crystal Eye concentrate the pointing capability of a γ-ray telescope and the sky coverage of an all-sky monitor in a single detector. Moreover, the use of Silicon Photomultiplier (SiPM) at the place of traditional PMs, besides being a challenge for their qualification for space missions, allows a more compact and less power-consuming design. A Crystal Eye pathfinder has been designed and realized to be tested in view of the mission on the Space Rider by ESA. The prototype is made by 4 pixels. The mission is aimed at testing in the space environment the LYSO crystals, the MPPC-arrays and the DAQ board.

3D Point Cloud Stitching for Object Detection with Wide FoV Using Roadside LiDAR

Light Detection and Ranging (LiDAR) is widely used in the perception of physical environment to complete object detection and tracking tasks. The current methods and datasets are mainly developed for autonomous vehicles, which could not be directly used for roadside perception. This paper presents a 3D point cloud stitching method for object detection with wide horizontal field of view (FoV) using roadside LiDAR. Firstly, the base detection model is trained by KITTI dataset and has achieved detection accuracy of 88.94. Then, a new detection range of 180° can be inferred to break the limitation of camera’s FoV. Finally, multiple sets of detection results from a single LiDAR are stitched to build a 360° detection range and solve the problem of overlapping objects. The effectiveness of the proposed approach has been evaluated using KITTI dataset and collected point clouds. The experimental results show that the point cloud stitching method offers a cost-effective solution to achieve a larger FoV, and the number of output objects has increased by 77.15% more than the base model, which improves the detection performance of roadside LiDAR.

Portable widefield fundus camera with high dynamic range imaging capability.

Fundus photography is indispensable for the clinical detection and management of eye diseases. Low image contrast and small field of view (FOV) are common limitations of conventional fundus photography, making it difficult to detect subtle abnormalities at the early stages of eye diseases. Further improvements in image contrast and FOV coverage are important for early disease detection and reliable treatment assessment. We report here a portable, wide FOV fundus camera with high dynamic range (HDR) imaging capability. Miniaturized indirect ophthalmoscopy illumination was employed to achieve the portable design for nonmydriatic, widefield fundus photography. Orthogonal polarization control was used to eliminate illumination reflectance artifacts. With independent power controls, three fundus images were sequentially acquired and fused to achieve HDR function for local image contrast enhancement. A 101° eye-angle (67° visual-angle) snapshot FOV was achieved for nonmydriatic fundus photography. The effective FOV was readily expanded up to 190° eye-angle (134° visual-angle) with the aid of a fixation target without the need for pharmacologic pupillary dilation. The effectiveness of HDR imaging was validated with both normal healthy and pathologic eyes, compared to a conventional fundus camera.

A dual channel decomposition and remapping fusion model for low illumination images with a wide field of view

In this paper, we investigate the problem of low illumination image enhancement under wide field of view condition. Our contribution consists of two parts: Firstly, we propose an adaptive two-parameter luminance remapping enhancement function (A2BREF) based on biological visual properties. Secondly, we propose a simple and effective noise suppression method for composite weighted map. In this paper, an image decomposition method based on the total variational energy is used to decompose the input image into structure and detail components. We apply luminance enhancement to the structure component and noise suppression to the detail component. The two components are processed in parallel without interfering with each other. First, we transform the structure component from RGB space to HSV space, and A2BREF combines the global and local luminance information of the input image to perform an adaptive luminance remapping of the V component. Then, the mapping result and the initial V component are fused with PCA in a specific order to enhance the image brightness. Secondly, the detail component contains a lot of noise and detail information of the input image. In this paper, we extract two weight maps from different stages of the detail component by means of improved adaptive Gaussian filters, and the two weight maps are combined to obtain the final weight map. After multiplying the weight maps with the initial detail components and stretching the contrast, the ideal detail components are obtained. Finally, the processed structure and detail components are combined to obtain the final result. The experimental results show that the proposed method has advantages over the contrast algorithm in terms of both subjective visual and objective metrics.

Determination of Platelet Count Estimation Factor on Peripheral Blood Smear Confirmation Using Field Number 22 Microscope

The automatic platelet count sometimes requires confirmation on the peripheral blood smear. Platelet count estimation can also be used for reporting platelet count if an automatic cell counter is not available, with an estimation factor according to the Field Number (FN) of the microscope used. This study aimed to determine the platelet count estimation factor based on peripheral blood smear confirmation using an FN 22 microscope. An observational cross-sectional study was carried out in patients who had routine hematological and peripheral blood smear examinations during September 2021 by determination of platelet count using the automatic cell counter method and an average number of platelet counts per field of view with 100x objective magnification. The estimation factor is the total ratio divided by sample size. The total ratio of 254 samples was 4.086. The platelet count estimation factor was 16, indicating that 1 platelet per field of view was equivalent to 16x103/µL. There was a very strong significant correlation between mean platelet count per field of view and platelet count using the automatic cell counter (p&lt;0.001, R&gt;0.750). The field number is the image diameter of the microscope eyepiece. The latest generations of microscope use FN 20 or more, which provides a wider field of view, enabling the observation of more platelets. Factor estimation was used to determine the estimated platelet count on a peripheral blood smear. A big difference between automatic cell counter and peripheral blood smear might indicate pre-analytic, analytic, and post-analytic errors. The platelet count estimation factor based on peripheral blood smear confirmation using the FN 22 microscope was 16. Each laboratory needs to determine the estimation factor according to the FN microscope used.

Tied-array beam localization of radio transients and pulsars

Abstract Multi-element interferometers such as MeerKAT, which observe with high time resolution and have a wide field of view, provide an ideal opportunity to perform real-time, untargeted transient and pulsar searches. However, because of data storage limitations, it is not always feasible to store the baseband data required to image the field of a discovered transient or pulsar. This limits the ability of surveys to effectively localize their discoveries and may restrict opportunities for follow-up science, especially of one-off events like some fast radio bursts. Here, we present a novel maximum-likelihood estimation approach to localizing transients and pulsars detected in multiple MeerKAT tied-array beams at once, which we call tied-array beam localization, as well as a Python implementation of the method named SeeKAT. We provide real-world examples of SeeKAT’s use as well as a Monte Carlo analysis to show that it is capable of localizing single pulses detected in beamformed MeerKAT data to (sub)arcsec precision.

Offline Calibration for Infant Gaze and Head Tracking across a Wide Horizontal Visual Field.

Most well-established eye-tracking research paradigms adopt remote systems, which typically feature regular flat screens of limited width. Limitations of current eye-tracking methods over a wide area include calibration, the significant loss of data due to head movements, and the reduction of data quality over the course of an experimental session. Here, we introduced a novel method of tracking gaze and head movements that combines the possibility of investigating a wide field of view and an offline calibration procedure to enhance the accuracy of measurements. A 4-camera Smart Eye Pro system was adapted for infant research to detect gaze movements across 126° of the horizontal meridian. To accurately track this visual area, an online system calibration was combined with a new offline gaze calibration procedure. Results revealed that the proposed system successfully tracked infants' head and gaze beyond the average screen size. The implementation of an offline calibration procedure improved the validity and spatial accuracy of measures by correcting a systematic top-right error (1.38° mean horizontal error and 1.46° mean vertical error). This approach could be critical for deriving accurate physiological measures from the eye and represents a substantial methodological advance for tracking looking behaviour across both central and peripheral regions. The offline calibration is particularly useful for work with developing populations, such as infants, and for people who may have difficulties in following instructions.

Enhancement of slope efficiency of a dually modulated photonic-crystal surface-emitting laser over a wide range of emission angles by introducing a backside reflector

Dually modulated photonic-crystal surface-emitting lasers (DM-PCSELs) are a new type of semiconductor laser that enable on-chip, mechanical-free, high-power, high-beam-quality 2D beam scanning over a wide field of view. These lasers are attracting attention for application in light detection and ranging, and the improvement of their slope efficiency is desired for this application. Thus far, the highest experimentally demonstrated slope efficiency is approximately 0.4 W/A at wavelengths of around 940 nm, which was limited by the fact that roughly half of the laser light was emitted toward and absorbed by the backside electrode. In this work, in order to improve the slope efficiency of DM-PCSELs, we utilize the light emitted toward the backside of the device by introducing a distributed Bragg reflector (DBR) as a backside reflector. In consideration of this laser’s ability to emit beams over a wide field of view, we design laser structures that facilitate a commensurate enhancement of efficiency at various emission angles. Next, we discuss the effect of the DBR on the confinement of transverse modes in thickness direction as well as the suppression of higher-order transverse modes. Then, we analyze the emission characteristics of a DM-PCSEL with a DBR and calculate that the theoretical slope efficiency is enhanced to 0.7–0.8 W/A, which is twice that of the device without a DBR, over a wide range of emission angles from 0° to 30°. We then fabricate the devices and experimentally demonstrate the emission of a single-lobed beam with a high slope efficiency of 0.7–0.8 W/A.

Design of a statically foveated display based on a perceptual-driven approach.

Foveated display technology has the potential to offer both a large field of view (FOV) and high spatial resolution for head-mounted display (HMD) systems, through allocating the limited resources differently between the region of interest (ROI) and the peripheral region. However, the common method used in the prior studies is based on a dual-resolution dynamic foveation scheme, which is inevitably complex and high cost due to the requirements for multiple display sources, a 2D steering mechanism, and an eye tracking device. We recently proposed a new perceptual-driven approach to design a statically foveated HMD with the goal of offering a wide FOV with nearly imperceptible or minimal degradation of the perceived image resolution within regions where frequent eye movement occurs. Compared to a dynamical dual-resolution foveation approach, it not only minimizes the hardware complexity by eliminating the need for an eyetracker, a scanning mechanism, and multiple display sources, but also offer continuous degradation in resolution to avoid visual artifacts. In this paper, a statically foveated display is designed by carefully controlling the spatial variation of optical magnification of the eyepiece optics, which covers an 80° FOV and achieves a peak resolution of 1.5 arcminutes per pixel. The angular resolution distribution of the prototype design closely matches the theoretical statically foveated scheme described in our previous work with excellent perceived performance. Finally, a foveated display prototype based on the design was experimentally demonstrated with excellent perceived performance matching the designed resolution distribution.

Full-color eye-box expansion via holographic volume gratings recorded in photo-thermo-refractive glass.

Conventional head-up displays (HUDs) suffer from a limited exit pupil and a lack of compactness mainly due to the use of bulky optics. HUDs need a high-quality image with a large field of view (FOV) in small packaging to gain commercial acceptability. Holographic HUDs are phase-only devices that allow vision correction and focus adjustment while having a wide FOV. However, the limited bandwidth of a spatial light modulator (SLM) imposes a trade-off between the FOV and eye-box size. Combining a holographic system with an image-replicating element eliminates such a tradeoff. For image replication, we designed and fabricated a compact 2D diffractive beam splitter formed from two perpendicular volume gratings operating in the Raman-Nath regime. The gratings were recorded holographically in photo-thermo-refractive (PTR) glass, with optimized index modulation, thickness, and period to provide uniform intensity distribution across all desired orders for the fundamental red, green and blue (RGB) colors. We demonstrated a full-color holographic projection with an eye-box expanded by the designed 2D diffractive beam splitters.

Towards the development of reliable and economical mHealth solutions: A methodology for accurate detection of Buruli ulcer for hard-to-reach communities

mHealth interventions have the potential to increase access to healthcare for the most hard-to-reach communities. For rural communities suffering disproportionately from skin-related NTDs, and Buruli ulcer, there is a need for low-cost, non-invasive and mobile tools for the early detection and management of disease. Dermoscopy is a noninvasive in-vivo technique that has been useful in improving the diagnostic accuracy of pigmented skin lesions based on anatomical features and morphological structures of lesions.ObjectivesUsing dermoscopy, this study develops the automated tools necessary for developing an effective mHealth intervention towards identifying BU lesions in the early stages. Methods: This imaging methodology relies on an external attachment, a dermoscope, which uses polarized light to cancel out skin surface reflections. In our initial studies we used a dermoscope with only crosspolarized white-light (DL100, 3Gen) but later we adopted a more advanced multispectral dermoscope (DLIIm, 3Gen). The latter employed additional monochromatic light at different wavelengths of the visible spectral range, specifically blue (470 nm), yellow (580 nm), and red (660 nm) color, to visualize pigmented structures of skin layers at different depths.ResultsResults obtained using a subset of 58 white-light images with confirmed diagnosis (16 lesions BU and 42 lesions non-BU) resulting in sensitivity of 100 and specificity of 88.10, with an overall accuracy of 94.05 at 95% CI. Performance obtained using a second dataset of 197 dermoscopic multispectral images (16 lesions BU and 181 lesions non-BU) resulted in sensitivity of 90.00% and specificity of 93.39% with a balanced accuracy of 91.69% (86.95% to 95.12% at 95% CI).ConclusionsThis system will continue to perform even as the technology evolves and newer dermoscopes are available. Subsequent studies involve the DL4 which provides more uniform and brighter illumination, higher lesion magnification, and wider field of view which, combined with the superb resolution of modern smartphones, can result in faster and more accurate lesion assessment. This is an important step for the development of mHealth tools for use by non-specialists in community settings for the early detection of Buruli ulcer, skin-NTDs, and other dermatologic conditions associated with disease, including wound healing and management of disease progression.

高分一号宽幅多光谱影像辐射定标偏差及其植被指数影响

PDF HTML阅读 XML下载 导出引用 引用提醒 高分一号宽幅多光谱影像辐射定标偏差及其植被指数影响 DOI: 10.5846/stxb202205241462 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划课题项目2019YFB2102004）；福建省自然科学基金项目（2021J011190）；厦门理工学院高层次人才项目（4010520004）；江西省水利科技项目（202224ZDKT11） Radiometric calibration bias of the Gaofen-1 WFV multispectral imagery and its influence on vegetation index Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:自2013年4月在轨运行以来，高分一号（GF-1）宽幅（WFV）多光谱相机已实现持续对地观测，为包括生态学在内的相关研究领域与行业应用提供了丰富的数据源。当前场地定标频次偏低以及定标参数更新、发布滞后的现状，一定程度上影响了GF-1 WFV多光谱数据的定量应用。然而，现有文献仅在数据预处理流程中谈及对GF-1 WFV影像的辐射定标处理，很少讨论定标参数选取不当甚至误用产生的可能影响。基于已公布的辐射定标参数（2014-2021年）和4景GF-1 WFV Level1A级影像产品数据，重点围绕辐射定标偏差及其对多光谱波段星上反射率和常用植被指数的影响等展开模型分析和讨论。结果显示：即使两个相邻年份间，在多数情况下误用辐射定标参数会导致不可忽视的波段星上反射率相对偏差；进而给不同类型植被指数的实际应用带来不同程度的挑战。因辐射定标偏差的影响，常用的两波段归一化型植被指数在监测稀疏植被覆盖区时会存在明显的误差；而对高植被覆盖区的监测时采用两波段简单比值型植被指数将面临更大的挑战。针对存档GF-1 WFV Level1A数据的应用需求，提出利用时间距离加权的线性内插法来修正基于公开定标参数的辐射定标结果，并通过案例分析表明了该处理方法的有效性。最后，希望研究结果能引起普通用户对卫星遥感影像辐射定标的关注和重视。 Abstract:Since its on-orbit operation in April 2013, the wide field of view (WFV) sensors onboard Gaofen-1 (GF-1), where "Gaofen" means high resolution in Chinese, have continuously collected multispectral imagery of the Earth's surface. The GF-1 WFV sensors have provided abundant data sources for many fields including ecology. The fact that insufficient site calibration (i.e. once a year) as well as the updates lag of calibration parameters might limit the quantitative application of the GF-1 WFV imagery to a certain extent. However, current literature has only mentioned radiometric calibration of the GF-1 WFV images as a pre-processing procedure, whereas has rarely discussed the possible impacts caused by improper selection or misuse of calibration parameters. Based on the radiometric calibration parameters published for the GF-1 WFV imagery (from 2014 to 2021) and four scenes of the Level1A data products, the issue on radiometric calibration bias was investigated. Furthermore, impacts of the radiometric calibration bias on the top of atmosphere (TOA) reflectance and on several vegetation indices commonly used were discussed accordingly. It showed that, generally, even the calibration difference between two neighboring years were considered, in most cases, improper selection of the calibration parameters could result in a significantly relative bias in the TOA reflectance. The bias in TOA reflectance further challenged different types of vegetation indices with varying degrees of patterns in practice. In particular, mainly due to the radiometric calibration biases, the obvious errors were more likely in the normalized difference vegetation index based on two bands, for monitoring sparse vegetation coverage area. Actually, the normalized difference vegetation index has been commonly used in assessing vegetation status as well as surface dynamics. At the same time, for monitoring high vegetation coverage area, the simple ratio vegetation index with two bands was possibly confronted with greater challenges. Consequently, to make full use of the GF-1 WFV Level1A products, it is critical to solve the radiometric calibration problems. In this study, a time weighted linear interpolation method was proposed. In the interpolation process for a specific GF-1 WFV imagery, both radiometric parameters obtained closely before and after the imagery acquisition were integrated. A case study suggested the effectiveness of the proposed processing to improve the radiometric calibration of the GF-1 WFV images in Level1A products, as compared against the results obtained merely based on public calibration parameters. Finally, general users should pay much attention to the radiometric calibration of satellite remotely sensed data (e.g., the GF-1 WFV multispectral imagery) for their quantitative applications, as discussed in this investigation. 参考文献 相似文献 引证文献

Speckle structured illumination endoscopy with enhanced resolution at wide field of view and depth of field

Structured illumination microscopy (SIM) is one of the most widely applied wide field super resolution imaging techniques with high temporal resolution and low phototoxicity. The spatial resolution of SIM is typically limited to two times of the diffraction limit and the depth of field is small. In this work, we propose and experimentally demonstrate a low cost, easy to implement, novel technique called speckle structured illumination endoscopy (SSIE) to enhance the resolution of a wide field endoscope with large depth of field. Here, speckle patterns are used to excite objects on the sample which is then followed by a blind-SIM algorithm for super resolution image reconstruction. Our approach is insensitive to the 3D morphology of the specimen, or the deformation of illuminations used. It greatly simplifies the experimental setup as there are no calibration protocols and no stringent control of illumination patterns nor focusing optics. We demonstrate that the SSIE can enhance the resolution 2–4.5 times that of a standard white light endoscopic (WLE) system. The SSIE presents a unique route to super resolution in endoscopic imaging at wide field of view and depth of field, which might be beneficial to the practice of clinical endoscopy.

Robust fully controlled nanometer liquid layers for high resolution liquid-cell electron microscopy.

Liquid cell electron microscopy (LCEM) has long suffered from irreproducibility and its inability to confer high-quality images over a wide field of view. LCEM demands the encapsulation of the in-liquid sample between two ultrathin membranes (windows). In the vacuum environment of the electron microscope, the windows bulge, drastically reducing the achievable resolution and the usable viewing region. Herein, we introduce a shape-engineered nanofluidic cell architecture and an air-free drop-casting sample loading technique, which combined, provide robust bulgeless imaging conditions. We demonstrate the capabilities of our stationary approach through the study of in-liquid model samples and quantitative measurements of the liquid layer thickness. The presented LCEM method confers high throughput, lattice resolution across the complete viewing window, and sufficient contrast for the observation of unstained liposomes, paving the way to high-resolution movies of biospecimens in their near native environment.

Imaging of calcium gradient oscillations in plant root hairs by light sheet fluorescence microscopy

Root hairs are a delicate single-cell system whose growth is regulated by a fine mechanism characterised by the presence of a tip-high Ca2+ gradient that shows regular oscillations in growing root hairs. We show a method based on the use of Light sheet fluorescence microscopy (LSFM) which allows the quasi-physiological analysis of Arabidopsis thaliana plant roots hairs with excellent spatial and temporal resolution over a wide field of view. We show how the healthy growing root hairs are linked to precise oscillations and how a disruption of this mechanism can be associated to specific genes.

Direct laser-writing of glass-based planar waveguide for fluorescence imaging

Fluorescent microscopic imaging technology has the characteristics of strong labeling capability, high signal strength, low experimental cost, simple imaging process, and imaging from living to in vitro, which is widely used in biological analysis imaging research such as tumor cell imaging, drug distribution in vivo detection, but how to simultaneously have both a wide field of view and a high resolution is a major difficulty in the current field of fluorescence microscopic imaging. Planar silicon waveguides have been found to be able to achieve a wide range of imaging of ultra-thin samples. However, they require sputtering deposition or ion beam etching and other preparation processes. The related processes are complex and equipment required is expensive. In this work, a planar-waveguide-type fluorescence microscope device based on direct picosecond-laser-writing is designed, in which picosecond laser is used to etch the glass surface to rapidly prepare micron sized grooves, and the low-cost and batch-preparation of glass based planar waveguides is further realized by spinning SU-8 photoresist. The waveguide diameter and depth can be customized by adjusting laser processing power, frequency, scanning speed and other parameters. The microscopic detection experiment with using Rhodamine B fluorescent molecule verifies that the direct laser-writing glass based planar waveguide fully meets the requirements for biological imaging with high resolution and large field of view. This simple and rapid processing method can effectively improve the the fluorescence imaging.