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In this paper we describe the Kottamia Faint Imaging Spectro-Polarimeter (KFISP) that has been recently developed and designed to be mounted at the Cassegrain focus of the 1.88 m telescope at Kottamia Astronomical Observatory (KAO), Egypt. The optical design of KFISP is developed such that it can be used in various modes of operation. These are: direct imaging, spectroscopic, polarimetric imaging, and spectro-polarimetric. The KFISP is an all-refractive design to meet the polarimetric requirements and includes a focal reducer with a corrector section, collimator section, parallel beam section (containing various imaging components), and camera section. The corrector section gives an unvignetted Field-of-View of 8ʹ × 8ʹ and the collimator section has a focal length of 305 mm and matches the focal ratio of the input beam. The parallel beam section is 200 mm long and near the middle of it there is an image of the telescope pupil. The camera section includes 5 elements and has a focal length of 154.51 mm which gives an instrument effective final focal ratio of f/6.14 (acting as a telescope focal reducer of 1:2 ratio). The KFISP contains an internal calibration system which hosts the calibration light injection system, an integrating sphere equipped with the required calibration light sources. The opto-mechanical parts of KFISP contain a double-layered carbon fiber strut structure and comprises its subsystems of slit and guider assemblies, filter wheel drawer, grism wheel drawer, polarimetric components cubical box, and CCD camera which is integrated with camera optics. The CCD camera has 2048 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\times$$\end{document}× 2048 pixels with 13.5-micron square pixel size. The camera is cooled by liquid Nitrogen and is fixed to the KFISP through the integrated camera lens. The KFISP has been fully commissioned, mounted and is being tested in all modes of operation. In this paper we introduce the ambitious scientific goals, the optical setups of KFISP, its opto-mechanical implementation and the performance analysis of the instrument. In addition, we describe the camera system, its performance, and its software control. Finally, we present a sample of the first light observations obtained from the instrument.

Diffractive lens arrays with overlapping apertures can produce spot arrays with high numerical apertures (NAs). Combined with low-NA objectives, they can measure a large area with high lateral resolution. However, for surface measurements, the axial resolution of such setups is still fundamentally limited by the objectives. In this work, we propose a new design of diffractive optical elements (DOEs) to overcome this problem. The proposed Direct-imaging DOEs can perform 3D high-NA multi-spot surface measurements. Laterally, a non-vanishing contrast up to 1448 lp/mm is measured with a USAF resolution target. Axially, an average height of 917.5 nm with a standard deviation of 49.9 nm is measured with a calibrated step height target of 925.5 nm.

Diffractive lens arrays with overlapping apertures can produce spots with high numerical apertures (NAs). Such diffractive optical elements (DOEs) can replace high-NA objectives and measure a large area with high resolution in transmission microscopes. However, in reflection microscopes for surface measurements, the axial resolution is still limited by the objectives. Direct-imaging DOEs are proposed to solve the problem. They can perform high-NA multi-spot measurement in reflection configurations in both lateral and axial directions. Experiments demonstrate a lateral non-vanishing contrast up to 1448 lp/mm and an axial response on a plane mirror with a full width at half maximum (FWHM) of 2.24 μm.

Integrated differential phase-contrast scanning transmission electron microscopy (iDPC-STEM) is capable of directly probing guest molecules in zeolites, owing to its sufficient and interpretable image contrast for both heavy and light elements under low-dose conditions. This unique ability is demonstrated by imaging volatile organic compounds adsorbed in zeolite Silicalite-1; iDPC-STEM was then used to investigate molybdenum supported on various zeolites including Silicalite-1, ZSM-5, and mordenite. Isolated single-Mo clusters were observed in the micropores of ZSM-5, demonstrating the crucial role of framework Al in driving Mo atomically dispersed into the micropores. Importantly, the specific one-to-one Mo-Al interaction makes it possible to locate Al atoms, that is, catalytic active sites, in the ZSM-5 framework from the images, according to the positions of Mo atoms in the micropores.

Imaging finer structural details of atomically precise noble metal cluster crystals has been difficult with electron microscopy, owing to their extreme beam sensitivity. Here we present a simple method whereby lattice planes in single crystals of nanoclusters can be observed using a conventional transmission electron microscope, enabling further expansion of cluster research.

The growing interest in the human subcortex is accompanied by an increasing number of parcellation procedures to identify deep brain structures in magnetic resonance imaging (MRI) contrasts. Manual procedures continue to form the gold standard for parcellating brain structures and is used for the validation of automated approaches. Performing manual parcellations is a tedious process which requires a systematic and reproducible approach. For this purpose, we created a series of protocols for the anatomical delineation of 21 individual subcortical structures. The intelligibility of the protocols was assessed by calculating Dice similarity coefficients for ten healthy volunteers. In addition, dilated Dice coefficients showed that manual parcellations created using these protocols can provide high-quality training data for automated algorithms. Here, we share the protocols, together with three example MRI datasets and the created manual delineations. The protocols can be applied to create high-quality training data for automated parcellation procedures, as well as for further validation of existing procedures and are shared without restrictions with the research community.

Santa Cruz Array of Lenslets for Exoplanet Spectroscopy (SCALES) is an instrument being designed for direct imaging of exoplanets in the mid-infrared with the Adaptive Optics System of the W.M. Keck Observatory. The performance of SCALES will be largely affected by thermal emission from the instrument structures. Placement of a pupil stop can limit the emission of instrument structures such as primary mirror segment gaps, secondary structures, and spider arms. Here we proposed a cold stop design of a circular inner mask paired with a serrated outer mask. Taking into account the pupil nutation, we modeled the throughput and the background emission for the design to optimize the dimensions of the cold stop.

Exoplanet science is one of the most thriving fields of modern astrophysics. A major goal is the atmospheric characterization of dozens of small, terrestrial exoplanets in order to search for signatures in their atmospheres that indicate biological activity, assess their ability to provide conditions for life as we know it, and investigate their expected atmospheric diversity. None of the currently adopted projects or missions, from ground or in space, can address these goals. In this White Paper, submitted to ESA in response to the Voyage 2050 Call, we argue that a large space-based mission designed to detect and investigate thermal emission spectra of terrestrial exoplanets in the mid-infrared wavelength range provides unique scientific potential to address these goals and surpasses the capabilities of other approaches. While NASA might be focusing on large missions that aim to detect terrestrial planets in reflected light, ESA has the opportunity to take leadership and spearhead the development of a large mid-infrared exoplanet mission within the scope of the “Voyage 2050” long-term plan establishing Europe at the forefront of exoplanet science for decades to come. Given the ambitious science goals of such a mission, additional international partners might be interested in participating and contributing to a roadmap that, in the long run, leads to a successful implementation. A new, dedicated development program funded by ESA to help reduce development and implementation cost and further push some of the required key technologies would be a first important step in this direction. Ultimately, a large mid-infrared exoplanet imaging mission will be needed to help answer one of humankind’s most fundamental questions: “How unique is our Earth?”, Experimental Astronomy, 54 (2-3), ISSN:0922-6435, ISSN:1572-9508

To obtain the ophthalmic findings for diagnosis and treatment, the ophthalmologist has been allowed to observe with a handheld ophthalmoscope in which the medical photos of findings cannot be recorded. Here, the simple optical system has been designed and implemented a prototype using 3D printing that can adapt to the smartphone with conventional app camera for direct imaging retinal blood vessels. A plano-convex lens of +20D was used to adjust the lens power of the smartphone camera. The lens wheel containing 16 lenses ranging from-8D to +8D and blank of 0D was used to compensate for tolerances and errors in human-eye sight. As a result, the prototype was constructed and able to capture images of the retinal blood vessels (RBV) in subject’s eyes having been either nearsighted or farsighted vision. Using this optical technique can provide the simple, portable and inexpensive prototype adapted to smartphone and can take advantage of global networks resource for telemedicine.

Terahertz radiation sources are currently one of the most widely used non-ionizing illumination mechanisms for security applications and also find increasing utilization in quality control of commercial products. Presently, a majority of these applications rely on scanning rather than direct imaging and implicitly suffer from temporal latency due to post processing. The monetary and temporal cost associated with procuring commercially manufactured optics that are suitable for imaging leads to fundamental limitations in the ability to rapidly develop application-specific imaging modalities using terahertz sources. Herein, we show a novel method for the rapid prototyping of metallic coated poly-methacrylate parabolic reflectors fabricated by stereolithographic 3D printing. Images comparing the performance of a commercially available off-axis parabolic reflector to our metalized poly-methacrylate prototype, which was designed to be identical to the commercially available mirror, are subsequently presented. The images show that at 530 GHz it is possible to produce a metalized poly-methacrylate off-axis paraboloid whose spatial beam profile is nearly identical to that of a commercially available equivalent.

Droplet microfluidics have a great potential in chemical and biomedical applications, due to their high throughput, versatility, and massive parallelism. To enhance their throughput, many devices based on the droplet microfluidics are using a flow-through configuration, in which the droplets are generated, transported, and analyzed in a continuous stream with a high velocity. Direct imaging of moving droplets is often necessary to characterize the spatiotemporal dynamics of the chemical reaction and physical process in the droplets. However, due to the motion blur caused by the movement of the droplets during exposure, an expensive high-speed camera is required for clear imaging, which is cost prohibitive in many applications. In this paper, we are presenting ‘Moving shot’ to demonstrate direct imaging of fast-moving droplets in microfluidic channels at an affordable cost. A microfluidic device is translated at the same velocity but in the opposite direction of moving droplets in it, so that the droplets are stationary with respect to the objective lens. With this approach, we can image fluorescent droplets moving at 0.34 cm s−1 with an exposure time up to 2 s without motion blur. We strongly believe that the proposed technique can enable cost-effective and high-throughput imaging of fast-moving droplets in a microfluidic channel.

Direct imaging of exoplanets is usually limited by quasi-static speckles. These uncorrected aberrations in a star’s point-spread function (PSF) obscure faint companions and limit the sensitivity of high-contrast imaging instruments. Most current approaches to processing differential imaging sequences like angular differential imaging and spectral differential imaging produce a self-calibrating data set that is combined using a linear least-squares solution to minimize the noise. Due to temporal and chromatic evolution of a telescope’s PSF, the best correlated reference images are usually the most contaminated by the planet, leading to self-subtraction and reducing the planet throughput. In this paper, we present an algorithm that directly optimizes the nonlinear equation for planet signal-to-noise ratio (S/N). This new algorithm does not require us to reject adjacent reference images and optimally balances noise reduction with self-subtraction. We then show how this algorithm can be applied to multiple images simultaneously for a further reduction in correlated noise, directly maximizing the S/N of the final combined image. Finally, we demonstrate the technique on an illustrative sequence of HR8799 using the new Julia-based Signal to Noise Analysis Pipeline. We show that S/N optimization can provide up to a 5× improvement in contrast close to the star. Applicable to both new and archival data, this technique will allow for the detection of fainter, lower mass, and closer-in companions, or achieve the same sensitivity with less telescope time.

Fluorescence lifetime imaging (FLI) has become an increasingly popular method in molecular imaging as it provides unique insights into the biological processes. However, despite its popularity and profound impact, FLI is not a direct imaging modality and datasets need to be postprocessed to quantify fluorescence lifetime or lifetime-based parameters. Such technical implementations can be complex, computationally expensive, require high level of expertise as well as user inputs. Herein, we will report on the development and validation of DL models as fast and user-friendly image formation tools for FLI, including outputting the quantitative lifetime image from raw FLI measurements without iterative solvers and user input, performing FLI topography corrected by the tissue optical properties and performing end-to-end 3D optical reconstructions.

We developed a quantum-inspired adaptive algorithm using spatial-mode-demultiplexing measurements to read incoherently illuminated barcodes at large distances. In simulations, our scheme accurately discriminates barcodes in 20x less time than direct imaging at a standoff of 1 km.

SHARK-NIR in an instrument that will provide direct imaging, coronagraphic imaging, dual band imaging and low resolution spectroscopy in Y, J and H bands, and it will be soon installed at the Large Binocular Telescope. Used in combination with SHARK-VIS (operating in V band) and LMIRCam of LBTI (operating from K to M bands), SHARKNIR will exploit coronagraphic simultaneous observations in three different wavelengths. Exoplanets search and characterization, young stellar systems, jets and disks are the main science cases, but the extreme performance of the LBT AO systems, above all in the faint end regime, will allow to open to science difficult to be achieved from other similar instruments, such as AGN and QSO morphological studies. A variety of coronagraphic techniques have been implemented, as the Gaussian Lyot, Shaped Pupil and Four Quadrant masks, with the aim to possibly have a suitable coronagraphic masks for each science case, since the coronagraphic requirement in term of contrast and inner and outer working angle are depending on the target and on the science to be achieved. We report here about the SHARK-NIR status, that should be installed at LBT in mid-2021

IMSP is the versatile first-light instrument under construction for the 4m telescope in China. The special feature of IMSP is the multimode operation modes and high-efficiency. Direct imaging mode is designed to work in a synchronous multi-color bands covering from 360 to 1700 nm using two dichroic mirrors with a 3’x3’ field of view (FOV). Long-slit spectrograph mode supports two spectral resolutions operation modes (R=1000 and 5000) via different combination of Volume Phase Holographic Prisms to cover the whole spectrum in visible. High resolution spectrograph mode (R=30000-60000) with wavelength range from 380 to 800 nm is reserved using fiber link system connected from Nasmyth foci to the enviroment controled room. The IMSP is planned to strart commssion at the end of 2021. In this paper, the lastest status of IMSP development will be given, including the final optical design and the integration of each sub-system.

The Gemini Planet Imager (GPI) is a high-contrast imaging instrument designed to directly image and characterize exoplanets. GPI is currently undergoing several upgrades to improve performance. In this paper, we discuss the upgrades to the GPI IFS. This primarily focuses on the design and performance improvements of new prisms and filters. This includes an improved high-resolution prism which will provide more evenly dispersed spectra across y, J, H and K-bands. Additionally, we discuss the design and implementation of a new low-resolution mode and prism which allow for imaging of all four bands (y, J, H and K-bands) simultaneously at R≈10. We explore the possibility of using a multiband filter which would block the light between the four spectral bands. We discuss possible performance improvements from the multiband filter, if implemented. Finally we explore the possibility of making small changes to the optical design to improve the IFS’s performance near the edge of the field of view., SPIE Astronomical Telescopes + Instrumentation, December 14-18, 2020, Online Only, United States, Series: Proceedings of SPIE

Remote sensing of Earth at ultraviolet wavelengths offers the capability to retrieve key environmental parameters that provide remarkable insight into space weather conditions. The miniaturized UV imager (MUVI) instrument is a currently funded NASA technology development effort that expands on capability developed from recent flight experience to build and qualify a small, relatively simple UV imager that can be tuned for a range of purposes. The goal is to revisit earlier designs of suppressive imagers, obviating the need for gratings, slits, and long optical paths, redeveloping a direct imaging capability in a CubeSat type form-factor. Combining high heritage components with improved imaging technologies, MUVI provides science performance comparable to high-performance imagers developed and flown for prior research missions at much lower mass and cost points. A compelling scientific design for future missions will be to make space-based observations from multiple vantage points from one or more orbit planes. Multiple-observatory mission designs, including those implemented using the CubeSat form-factor, are more accessible now due to a great deal of research and commercial work toward miniaturization of spacecraft subsystems. It is likely that small scientific payloads will greatly benefit upcoming Heliophysics missions if appropriate technologies are developed. An overview of the MUVI instrument is described here, along with development status after year 1 of funding.

There is a growing motivation for imaging regional lung ventilation. Global measures of lung function such as spirometry are not able to distinguish patterns of obstruction and regional reversibility in response to intervention. Advantages of MRI for lung imaging include use of nonionizing radiation and flexibility for acquiring dynamic, multidimensional signal changes in response to changes in lung function. For these reasons, MRI is particularly attractive for longitudinal studies of chronic lung disease, especially in pediatric populations. There are two broad classes of ventilation imaging methods using MRI, which have matured over the past decade: proton-based methods and direct imaging of exogenous gases using multinuclear MRI and spectroscopy. This chapter will provide a review of the theory and rationale of ventilation imaging with MRI, results of clinical research in ventilation MRI, and emerging methods of ventilation imaging. Proton MRI ventilation imaging techniques covered in this chapter include deformable image registration, Fourier decomposition, and oxygen-enhanced methods. This chapter also covers ventilation techniques utilizing MRI of visible gas nuclei, including hyperpolarized gas MRI and perfluorinated gas MRI.

Astronomy and science are fields in which specific groups remain under-represented despite multiple studies that investigate this issue and propose solutions. In this article, we analyze the demographics and social behavior of the exoplanet direct imaging community. Our focus is on identifying possible under-representation among this group, and quantifying inappropriate social behaviors. During the Spirit of Lyot conference 2019 (Tokyo, Japan), we conducted a survey that gathered a participation rate of 53\%. We analyzed the data collected under the prisms of gender balance and seniority representation. The proportions of women and of non-binary persons reveal a more diverse community in comparison to the other scientific groups (e.g. the IAU members), but still far from a balanced representation of all genders. Early-career scientists appear to have a lower visibility in the field than permanent researchers, with PhD students being under-represented at international conferences, and postdocs being excluded from conference Science Organizing Committees. Regarding social relations, the results are alarming, in particular when it comes to self-censoring of women or to unprofessional behavior, which was experienced by 54\% of this community (gender-biased behavior: 29\%; oral interruption: 33\%; inappropriate behavior: 33\%), and in particular by women. We recommend the community to become pro-active to build a safe environment and to continue its inclusion efforts. One aspect could be to systematically include socio-demographic surveys in conference registration forms to monitor the evolution of the community, in particular at larger scales. To do so, the survey questions available on GitHub., Comment: 17 pages, 14 figures

Following earlier proposals for optical stellar interferometer concepts in space and on the Moon, the improved ‘hypertelescope’ version capable of direct high-resolution imaging with a high limiting magnitude became tested on Earth, proposed for space, and is now also proposed for the Moon. Many small mirrors can be dilutely arrayed in a lunar impact crater spanning 10–25 km. And a larger version, modified for a flat lunar site and spanning up to several hundred kilometres can be built later if needed for a higher resolution and limiting magnitude. Even larger versions, at the scale of many thousand kilometres, also appear feasible in space at some stage, in the form of a controlled flotilla of mirrors. Among the varied science targets considered with the imaging resolution expected, reaching 100 nano-arcseconds on the Moon, are: (a) the early detection and resolved imaging of Near Earth Objects, and their monitoring for eventual collision avoidance by orbital deflection; (b) multi-pixel imaging of exoplanets as part of the search for exolife by mapping local seasonal spectral variations; (c) the physics of neutron stars and black holes at the galactic centre and in other Active Galactic Nuclei; and (d) distant galaxies of cosmological interest.This article is part of a discussion meeting issue ‘Astronomy from the Moon: the next decades’.

The x-z cross-sectional profiles of fluorescent objects can be distorted in confocal microscopy, in large part due to mismatch between the refractive index of the immersion medium of typical high numerical aperture objectives and the refractive index of the medium in which the sample is present. Here, we introduce a method to mount fluorescent samples parallel to the optical axis. This mounting allows direct imaging of what would normally be an x-z cross-section of the object, in the x-y plane of the microscope. With this approach, the x-y cross-sections of fluorescent beads were seen to have significantly lower shape-distortions as compared to x-z cross-sections reconstructed from confocal z-stacks. We further tested the method for imaging of nuclear and cellular heights in cultured cells, and found that they are significantly flatter than previously reported. This approach allows improved imaging of the x-z cross-section of fluorescent samples. LAY DESCRIPTION: Optical distortions are common in confocal microscopy. In particular, the mismatch between the refractive index of the immersion medium of the microscope objective and the refractive index of the sample medium distorts the shapes of fluorescent objects in the x-z plane of the microscope. Here, we introduced a method to eliminate the shape-distortion in the x-z cross-sections. This was achieved by mounting fluorescent samples on vertical glass slides such that the cross-sections orthogonal to the glass surface could be imaged in the x-y plane of the microscope. Our method successfully improved the imaging of nuclear and cellular heights in cultured cells and revealed that the heights were significantly flatter than previously reported with conventional approaches.

Monitoring a large active region in the farside of the Sun is important for space weather forecasting. However, direct imaging of the farside is currently not available and usually physicists rely on seismic holography to infer farside magnetograms. On other hand, mapping between holography and magnetic images is non-trivial. In this work, Generative Adversarial Network (GAN) is used; which consists of a pyramid of modified pixel2pixel architectures to capture internal distributions at different scales with higher quality. Generative model is trained and evaluated using frontside of Solar Dynamic Observatory (SDO): Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) magnetograms. Farside solar magnetograms from Extreme UltraViolet Imager (EUVI) farside data is also generated. The generative model successfully generates frontside solar magnetograms and outperforms state-of-the art method. It also help to monitor the magnetic changes from farside to frontside using generated solar magnetograms.

The generalized Hough transform (GHT) is a well-established technique for the recognition of geometrical fea- tures out of images corrupted by noise, with disconnected boundaries or where the target is partially occluded. As an alternative to the conventional procedure of direct imaging of the scene of interest and mapping to an accumulator or Hough parameter space, we can directly obtain the image transformed under GHT in an incoherently illuminated optical architecture where the pupil is codified according to the target of interest. Parallel processing inherent of optical devices then allows for real-time performance and shift-invariant pattern recognition. Besides, by exploiting the redundancy derived from multiview sensing of the input and its out- of-focus capture with an adequate pupil array, we can obtain in a snapshot the GHT with invariance to target shift, scale, and orientation. Finally, in order to enhance the robustness of the original algorithm in detecting an object out of a single image, we can also consider matching of a pair of corresponding (according to a perspective shift) templates to a given stereo pair of a 3d scene, since the redundancy that results from the simultaneous transformation of both images can overcome the drawbacks (resulting for example from occlusion) that affect the separate matching of an individual template to a given image.

We present a technique for squeezed light detection based on direct imaging of the displaced-squeezed-vacuum state using a CCD camera. We show that the squeezing parameter can be accurately estimated using only the first two moments of the recorded pixel-to-pixel photon fluctuation statistics, with accuracy that rivals that of the standard squeezing detection methods such as a balanced homodyne detection. Finally, we numerically simulate the camera operation, reproducing the noisy experimental results with low signal samplings and confirming the theory with high signal samplings., Comment: 5 pages, 4 figures, supplemental information included, comments are very welcome

Rapid development in biomedical science, consumer electronics, and software algorithm, has led to the fast growth in smartphone-based diagnostics. Given the advantages of cost-effectiveness, easy sample handling, and rapid readout of results, smartphone devices have become an ideal candidate in the application of point-of-care (POC) diagnostics. In this chapter, fundamental principles and clinical applications of smartphone-based diagnostics are discussed. Optical methods remain to be the dominant approach in smartphone-based detection. A number of imaging and quantitative analysis methods, including bright-field imaging, fluorescence imaging, computational imaging, colorimetric sensing, and fluorometric sening, are introduced. Quantification of biomarker concentrations, as well as direct imaging of pathogenic microbes and cells, provide essential information in disease diagnostics. Based on these techniques, various diagnostic applications of smartphone devices are surveyed, including detection of nutrient ions, small molecules, proteins, nucleic acids, bacteria, parasites, and human cells. This transformative tool timely fills the gap between advanced diagnostic technologies and patients in resource-limited settings.

Summary High resolution FWI shows the potential to evolve from a tool for velocity model building into a tool for direct imaging and direct interpretation. The use of incomplete physics (i.e. inverting for acoustic or visco-acoustic properties) and the associated leakage of unexplained elastic and anisotropic parameters into compressional velocity can be somewhat mitigated by access to well logs for validation and/or correction of the model generated. In the long run we hope to see FWI incorporating more-realistic physics, but careful analysis of high-resolution acoustic velocity models – coupled with a clear understanding of their limitations – can in the meantime still add tremendous value to asset teams.

Higher indium incorporation in self-organized triangular nanoprisms at the edges of InGaN/GaN core-shell nanorods is directly evidenced by spectral cathodoluminescence microscopy in a scanning transmission electron microscope. The nanoprisms are terminated by three 46 nm wide a-plane nanofacets with sharp interfaces forming a well-defined equilateral triangular base in the basal plane. Redshifted InGaN luminescence and brighter Z-contrast are resolved for these structures compared to the InGaN layers on the nanorod sidewalls, which is attributed to at least 4 % higher indium content. Detailed analysis of the inner optical and structural properties reveals luminescence contributions from 417 nm up to 500 nm peak wavelength proving the increasing indium concentration inside the nanoprism towards the nanorod surface.

The detection of exoplanets is a hot topic in international astronomy nowadays. The methods of exoplanets detection are mainly divided into indirect detection and direct imaging. Direct imaging of exoplanets is being pursued by a number of research groups around the world. In this paper, the research status of space-based direct imaging technologies for exoplanets detection is reviewed, and the advantages and disadvantages of related technologies are analyzed and summarized. The most advantageous and promising space-based nulling interferometry technologies are described in detail, including some laboratory verification studies based on ground-based astronomical telescopes. With the continuous development of spacecraft micro-Newton propulsion and high-precision positioning control, ultra-high-precision laser measurement, adaptive optics, integrated optics, etc., space-based direct imaging technologies for exoplanets detection will continue to make breakthroughs.

Introduction Today, rapid technical and clinical developments result in an increasing number of treatment options for oncological diseases. Thus, decision support systems are needed to offer the right treatment to the right patient. Imaging biomarkers hold great promise in patient-individual treatment guidance. Routinely performed for diagnosis and staging, imaging datasets are expected to hold more information than used in the clinical practice. Radiomics describes the extraction of a large number of meaningful quantitative features from medical images, such as computed tomography (CT) and positron emission tomography (PET). Due to the non-invasive nature and ability to capture 3D image-based heterogeneity, radiomic features are potential surrogate markers of the cancer phenotype. Several radiomic studies are published per day, owing to encouraging results of many radiomics-based patient outcome models. Despite this comparably large number of studies, radiomics is mainly studied in proof of principle concept. Hence, a translation of radiomics from a hot topic research field into an essential clinical decision-making tool is lacking, but of high clinical interest. Evidence acquisition Herein, we present a literature review addressing the clinical evidence of CT and PET radiomics. An extensive literature review was conducted in PubMed, including papers on robustness and clinical applications. Evidence synthesis We summarize image-modality related influences on the robustness of radiomic features and provide an overview of clinical evidence reported in the literature. Today, more evidence has been provided for CT imaging, however, PET imaging offers the promise of direct imaging of biological processes and functions. We provide a summary of future research directions, which needs to be addressed in order to successfully introduce radiomics into clinical medicine. In comparison to CT, more focus should be directed towards harmonization of PET acquisition and reconstruction protocols, which is important for transferable modelling. Conclusions Both CT and PET radiomics are promising pre-treatment and intra-treatment biomarkers for outcome prediction. Most studies are performed in retrospective setting, however their validation in prospective data collections is ongoing.

To utilize the 3D inversion recovery prepared ultrashort echo time with cones readout (IR-UTE-Cones) MRI technique for direct imaging of lamellar bone with comparison to the gold standard of computed tomography (CT). CT and MRI was performed on 11 shoulder specimens and three patients. Five specimens had imaging performed before and after glenoid fracture (osteotomy). 2D and 3D volume-rendered CT images were reconstructed and conventional T1-weighted and 3D IR-UTE-Cones MRI techniques were performed. Glenoid widths and defects were independently measured by two readers using the circle method. Measurements were compared with those made from 3D CT datasets. Paired-sample Student’s t tests and intraclass correlation coefficients were performed. In addition, 2D CT and 3D IR-UTE-Cones MRI datasets were linearly registered, digitally overlaid, and compared in consensus by these two readers. Compared with the reference standard (3D CT), glenoid bone diameter measurements made on 2D CT and 3D IR-UTE-Cones were not significantly different for either reader, whereas T1-weighted images underestimated the diameter (mean difference of 0.18 cm, p = 0.003 and 0.16 cm, p = 0.022 for readers 1 and 2, respectively). However, mean margin of error for measuring glenoid bone loss was small for all modalities (range, 1.46–3.92%). All measured ICCs were near perfect. Digitally registered 2D CT and 3D IR-UTE-Cones MRI datasets yielded essentially perfect congruity between the two modalities. The 3D IR-UTE-Cones MRI technique selectively visualizes lamellar bone, produces similar contrast to 2D CT imaging, and compares favorably to measurements made using 2D and 3D CT.

Purpose Individuals with velopharyngeal dysfunction (VPD) often present with hypernasality and airflow distortions during speech that negatively affect communication skills. Direct imaging allows f...

Fresnel incoherent correlation holography (FINCH) is a self-interference incoherent digital holography technique. It possesses a higher lateral resolution than an equivalent incoherent imaging system. However, FINCH has lower axial resolution than the direct imaging systems with the same numerical aperture. A decade after the FINCH invention, a different incoherent holographic method named coded aperture correlation holography (COACH) was developed with improved axial resolution but with the same lateral resolution as direct imaging. In this study, we propose and demonstrate a variant of COACH called coded aperture with FINCH intensity responses (CAFIR) with an improved lateral resolution that is similar to the FINCH system while maintaining its high axial resolution similar to the direct imaging system. CAFIR is implemented with coded phase masks to generate an ensemble of quasi-randomly distributed FINCH-like responses. Point spread holograms and object holograms are recorded under identical conditions, and they are cross-correlated to obtain the image reconstruction. Imaging of a multiplane object is studied to compare the axial resolution of CAFIR with FINCH and direct imaging systems.

Simulations of exoplanet albedo profiles are key to planning and interpreting future direct imaging observations. In this paper we demonstrate the use of the Planetary Spectrum Generator to produce simulations of reflected light exoplanet spectra. We use PSG to examine multiple issues relevant to all models of directly imaged exoplanet spectra and to produce sample spectra of the bright, nearby exoplanet $\upsilon$ Andromedae d, a potential direct imaging target for next-generation facilities. We introduce a new, fast, and accurate subsampling technique that enables calculations of disk-integrated spectra one order of magnitude faster than Chebyshev-Gauss sampling for moderate- to high-resolution sampling. Using this method and a first-principles-derived atmosphere for $\upsilon$ And d, we simulate phase-dependent spectra for a variety of different potential atmospheric configurations. The simulated spectra for $\upsilon$ And d include versions with different haze and cloud properties. Based on our combined analysis of this planet's orbital parameters, phase-and illumination-appropriate model spectra, and realistic instrument noise parameters, we find that $\upsilon$ And d is a potentially favorable direct imaging and spectroscopy target for the Coronagraph Instrument (CGI) on the Nancy Grace Roman Space Telescope. When a noise model corresponding to the Roman CGI SPC spectroscopy mode is included, PSG predicts the time required to reach a signal-to-noise ratio of 10 of the simulated spectra in both the central wavelength bin of the Roman CGI SPC spectroscopy mode (R=50 spectrum) and of the Band 1 HLC imaging mode is approximately 400 and less than 40 hr, respectively. We also discuss potential pathways to extricating information about the planet and its atmosphere with future observations and find that Roman observations may be able to bound the interior temperature of the planet., 23 pages, 14 figures

We introduce qualitative methods for locating small objects using time dependent acoustic near field waves. These methods have reduced data collection requirements compared to typical qualitative imaging techniques. In particular, we only collect scattered field data in a small region surrounding the location from which an incident field was transmitted. The new methods are partially theoretically justified and numerical simulations demonstrate their efficacy. We show that these reduced data techniques give comparable results to methods which require full multistatic data and that these time dependent methods require less scattered field data than their time harmonic analogs.

PET/MR is a new promising multi-modality imaging approach. Attenuation is by far the largest correction required for quantitative PET imaging. MR based attenuation correction have been extensively pursued, especially for brain imaging in the past several years. In this article, we will focus on reviewing atlas and direct imaging MR based PET attenuation correction methods. The technical principles behind these methods are detailed and the advantages and disadvantages of these methods are discussed.

Colorectal cancer (CRC) is the third most common cancer in both males and females in the UK giving rise to approximately 40,000 new cancer cases per year. It arises from polyps as part of the adenoma-carcinoma sequence. Early detection can aid treatment and improve outcomes. Faecal occult blood (FOBt) and direct imaging using colonoscopy/sigmoidoscopy has been shown to be advantageous in the detection of polyps and earlier cancer. We review the evidence and provide summaries of current strategies as well as future potential developments.