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The system is based on combined detector: scintillating plate+image intensifier+CCD matrix. The sensitivity of the detector allows the detection of single photon with energy higher than 60 keV. The hexagonal URA masks of ranks 6 and 9 are used for coded mask imaging; transparent elements of mask are cylindrical holes of diameter 1.3–2.2 mm). The im...
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... industrial GammaVisor prototype consists of the measuring unit and the control computer. The measuring unit (Fig. 1) includes the measuring head, the rotation gear and the TV camera. In the version of the imager shown, the rotation gear provides the turning of the measuring head in a ver- tical plane in limits !45° to #45°. Digitized optical images are used for identification of the radioactive objects. For this purpose superimpos- ing of optical and ...
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Several techniques can be used to determine the total efficiency including Monte Carlo simulations, semi-empirical methods and experimental measurements. The first technique requires a good definition of the geometry and materials, including window thickness together with an accurate set of cross-sections. The second technique requires two differen...
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... The coded aperture method has been used on spacecraft to image astrophysical X-ray sources [17][18][19] . It has also been used in laboratory to produce time-integrated images of stationary radioactive sources 12,20,21 . However, it has not previously been used to produce time-resolved images of transient, low-intensity, suprathermal X-rays from laboratory plasma experiments. ...
A PIN-diode-based 1D x-ray camera and a scintillator-based 1D x-ray camera, both with a microsecond to submicrosecond time resolution, have been developed to perform time-resolved imaging of transient, low-intensity, suprathermal x-rays associated with magnetohydrodynamic instabilities disrupting a plasma jet. These cameras have a high detection efficiency over a broad x-ray band, a wide field of view, and the capability to produce [Formula: see text] time-resolved frames with a [Formula: see text] μs time resolution. The x-ray images are formed by a pinhole or by a coded aperture placed outside a vacuum chamber in which the plasma jet is launched. The 1D imaging shows that the location of the x-ray source is either a few centimeters away from an inner disk electrode or near a spatially translatable metal frame that is 30–40 cm away from the electrode. Compared to a pinhole, a coded aperture increases the signal collection efficiency but also introduces unwanted artifacts.
... Pinhole cameras have been used extensively in scientific imaging applications [20][21][22], and serve as the basis for the camera model which underpins many geometric vision algorithms [23]. However, papers which leverage actual pinhole cameras, as opposed to the model, for computer vision have been sparse in the literature. ...
Modern machine learning has enhanced the image quality for consumer and mobile photography through low-light denoising, high dynamic range (HDR) imaging, and improved demosaicing among other applications. While most of these advances have been made for normal lens-based cameras, there has been an emerging body of research for improved photography for lensless cameras using thin optics such as amplitude or phase masks, diffraction gratings, or diffusion layers. These lensless cameras are suited for size and cost-constrained applications such as tiny robotics and microscopy that prohibit the use of a large lens. However, the earliest and simplest camera design, the camera obscura or pinhole camera, has been relatively overlooked for machine learning pipelines with minimal research on enhancing pinhole camera images for everyday photography applications. In this paper, we develop an image restoration pipeline of the pinhole system to enhance the pinhole image quality through joint denoising and deblurring. Our pipeline integrates optics-based filtering and reblur losses for reconstructing high resolution still images (2600 × 1952) as well as temporal consistency for video reconstruction to enable practical exposure times (30 FPS) for high resolution video (1920 × 1080). We demonstrate high 2D image quality on real pinhole images that is on-par or slightly improved compared to other lensless cameras. This work opens up the potential of pinhole cameras to be used for photography in size-limited devices such as smartphones in the future.
... Pinhole cameras have been used extensively in scientific imaging applications [47,20,30]. Computer vision owes a large debt to the pinhole camera, particularly in the camera model that underpins many geometric vision algorithms [54]. ...
The lensless pinhole camera is perhaps the earliest and simplest form of an imaging system using only a pinhole-sized aperture in place of a lens. They can capture an infinite depth-of-field and offer greater freedom from optical distortion over their lens-based counterparts. However, the inherent limitations of a pinhole system result in lower sharpness from blur caused by optical diffraction and higher noise levels due to low light throughput of the small aperture, requiring very long exposure times to capture well-exposed images. In this paper, we explore an image restoration pipeline using deep learning and domain-knowledge of the pinhole system to enhance the pinhole image quality through a joint denoise and deblur approach. Our approach allows for more practical exposure times for hand-held photography and provides higher image quality, making it more suitable for daily photography compared to other lensless cameras while keeping size and cost low. This opens up the potential of pinhole cameras to be used in smaller devices, such as smartphones.
... In the past, coded aperture imaging is widely used in the field where X-ray and gamma-ray imaging system [37]- [41]. Because X-ray and gamma-ray are difficult to be refracted or reflected by common optical elements like lens or mirrors, one solution for X-ray and gamma-ray detection is the pinhole camera. ...
... However, tiny pinholes account for low light transmittance and hence the low signal-to-noise ratio. To address the problem, the scatter-hole cameras [38] and many coded-aperture cameras [37], [39]- [41]. are proposed. ...
Conventional stereoscopic displays suffer from vergence-accommodation conflict which cause visual fatigue. Integral imaging-based (II) displays resolves this problem by directly projecting light field sub-views into the eye using microlens arrays. However, II-based light field displays has inherent trade-off between angular and spatial resolutions. In this paper, we propose a novel display concept called coded time-division light field display (C-TDM-LFD), which projects encoded light field sub-views to the viewers' eyes, offering correct cues for vergence-accommodation reflex. By jointly optimizing display inputs and pattern of coded apertures, our pipeline can render high resolution refocused images from sparse light field sub-views with minimal aliasing effects. By simulating light transport and image formation with Fourier optics, we can learn display inputs and coded aperture patterns via deep learning in an end-to-end fashion. To our knowledge, we are among the first to optimize the light field display pipeline with deep learning. We verify our concept with objective image quality metrics (PSNR, SSIM) and optics software simulation, and perform extensive studies on the various customizable design variables in our display pipeline. Experiments results show that our method can generate refocused images with higher quality both quantitatively and qualitatively compared to baseline display designs.
... It however poses several restrictions from the practical point of view, due to the heavy weight of the instrument in question, as well as the lowest amount of incident photons allowed through such a small frond-end opening. In order to improve all these aspects, the implementation of a coded aperture technique was first tested by the Kurchatov Institute [79] and then by CEA [80]. ...
This paper reports on the state-of-the-art of the main non-destructive assay (NDA) techniques usually used for in-situ radiological characterization of nuclear facilities subject to a decommissioning programme. For the sake of clarity and coherence, they have been classified as environmental radiation monitoring, surface contamination measurements, gamma spectrometry, passive neutron counting and radiation cameras. Particular mention is also made here to the various challenges that each of these techniques must currently overcome, together with the formulation of some proposals for a potential evolution in the future.
... It however poses several restrictions from the practical point of view, due to the heavy weight of the instrument in question, as well as the lowest amount of incident photons allowed through such a small frond-end opening. In order to improve all these aspects, the implementation of a coded aperture technique was first tested by the Kurchatov Institute [79] and then by CEA [80]. ...
In this paper, in-situ radiological characterisation by means of non-destructive techniques is studied and analysed in the context of the different constrained environments (identified as radioactivity, materials, accessibility and other hazards) that may be encountered in the nuclear facilities undergoing decommissioning and dismantling. As a complement to a previous paper (Aspe et al., 2020), the present one gives a global guidance to assist with the decision making process regarding the selection of in-situ measurement techniques that could be applied in such constrained environments.
In addition, from the definition of the investigation objectives, and for each one of the most common in-situ measurement techniques, a brief description is given about the impact of the above constraints and how to integrate them onto the system definition, including the experimental design, the mechanical integration and the data management, to properly define the best radiological characterization methodology.
Moreover, complementing this general view, all the phases – from initial to final – of a D&D programme were taken into account to provide basic recommendations, together with some particular dispositions, for the appropriate implementation of the chosen instruments.
Strengths and weaknesses of the common detectors used for the different in-situ measurement techniques, as well as their recommended applications in nuclear facilities are also outlined.
... MeV x-rays, requiring aperture perforation diameters of 1.3-2.2 mm [21]. Here, we demonstrate that the resolution limit may be extended by orders of magnitude, since the decoding process is able to discard A c c e p t e d M a n u s c r i p t the background arising from imperfect attenuation. ...
Laser-plasma x-ray sources have garnered interest from various communities due to their ability to generate high photon-energies from a small source size. The passive imaging of high energy x-rays and neutrons is also a useful diagnostic in laser-driven fusion capsules as well as laboratory astrophysics experiments which aim to study small samples of transient electron-positron plasmas. Here we study a coded aperture with scatter and partial attenuation included, which we call a 'CASPA', and compare them to the more common method of pinhole imaging. As well as discussing the well-known increased throughput of coded apertures, we also show that the decoding algorithm relaxes the need for a thick substrate. We simulate a 511 keV x-ray source through ray-tracing and Geant4 simulations to show how incomplete attenuation of the source by the mask may be less detrimental to imaging using a CASPA than to using a standard pinhole system.
... On the world market there are first commercially produced cameras [8,9,24]. The last two decades were time of the research and development to create a lighter and more comfortable in use cameras [13,14,[19][20][21][27][28][29]. Finally, in recent years, very compact and lightweight cameras [24 -26] weighing about 2-3 kilograms arisen. ...
The results of work on dismantling the graphite masonry and reactor structures of the RFT research reactor at the National Research Center Kurchatov Institute are presented. Remote-controlled technology and remote-sensing measurements of contamination levels were used to perform the operations of removing radioactive structures. Such methods have significantly reduced the impact of the radiation on the workers, the general public living in nearby urban areas, and the environment. The measurements of the dose rate in the masonry channels are presented and the total 137Cs activity in the graphite is determined.
... This fraction can be incremented only by increasing the diameter of the pinhole, thus significantly degrading the spatial resolution of the gamma images obtained. In order to improve the sensitivity and meanwhile the overall signal-to-noise ratio of the radiation images obtained, CEA developed in collaboration with the Kurchatov Institute [44] a gamma camera based on the coded aperture technique [8]. ...
A coded aperture gamma camera for retrieving the three-dimensional (3-D) position of radioactive sources is presented. This is of considerable interest for a wide number of applications, ranging from the reconstruction of the 3-D shape of radioactive objects to augmented reality systems. Current portable γ-cameras only provide the relative angular position of the hotspots within their field of view. That is, they do not provide any metric information concerning the located sources. In this study, we propose two approaches to estimate the distance of the surrounding hotspots, and to autonomously determine if they are occluded by an object. The first consists in combining and accurately calibrating the gamma camera with a structured-light depth sensor. The second approach allows the estimation of the source-detector distance by means of stereo gamma imaging. To geometrically align the images obtained by the gamma, depth, and optical cameras used, a versatile calibration procedure has been designed and carried out. Such procedure uses a calibration phantom intentionally easy to build and inexpensive, allowing the procedure to be performed with only one radioactive point source. Experimental results showed that our calibration procedure yields to sub-pixel accuracy both in the re-projection error and the overlay of radiation and optical images. A quantitative analysis concerning the accuracy and resolution of the retrieved source-detector distance is also provided, along with an insight into the respective most influential factors. Moreover, the results obtained validated the choice of the geometry of the pinhole model for a coded aperture gamma camera.
... On the world market there are first commercially produced cameras [8,9,24]. The last two decades were time of the research and development to create a lighter and more comfortable in use cameras [13,14,[19][20][21][27][28][29]. Finally, in recent years, very compact and lightweight cameras [24 -26] weighing about 2-3 kilograms arisen. ...
With the examples of developments carried out in the Kurchatov Institute and by the world leaders in the field the presentation considers the devices and methods to obtain remotely information on the distribution of radioactivity in radwaste and SNF. It describes the different types of light portable gamma cameras. The application of scanning spectrometric systems is considers also. The methods of recording UV radiation for detection of alpha contamination with the luminescence of air are presented. We discuss the scope and tasks that can be solved using remote and non-destructive methods.
