Concept Of Camera Research Articles

Image Mosaicking Approach for a Double-Camera System in the GaoFen2 Optical Remote Sensing Satellite Based on the Big Virtual Camera.

The linear array push broom imaging mode is widely used for high resolution optical satellites (HROS). Using double-cameras attached by a high-rigidity support along with push broom imaging is one method to enlarge the field of view while ensuring high resolution. High accuracy image mosaicking is the key factor of the geometrical quality of complete stitched satellite imagery. This paper proposes a high accuracy image mosaicking approach based on the big virtual camera (BVC) in the double-camera system on the GaoFen2 optical remote sensing satellite (GF2). A big virtual camera can be built according to the rigorous imaging model of a single camera; then, each single image strip obtained by each TDI-CCD detector can be re-projected to the virtual detector of the big virtual camera coordinate system using forward-projection and backward-projection to obtain the corresponding single virtual image. After an on-orbit calibration and relative orientation, the complete final virtual image can be obtained by stitching the single virtual images together based on their coordinate information on the big virtual detector image plane. The paper subtly uses the concept of the big virtual camera to obtain a stitched image and the corresponding high accuracy rational function model (RFM) for concurrent post processing. Experiments verified that the proposed method can achieve seamless mosaicking while maintaining the geometric accuracy.

A Multimodality Hybrid Gamma-Optical Camera for Intraoperative Imaging.

The development of low profile gamma-ray detectors has encouraged the production of small field of view (SFOV) hand-held imaging devices for use at the patient bedside and in operating theatres. Early development of these SFOV cameras was focussed on a single modality—gamma ray imaging. Recently, a hybrid system—gamma plus optical imaging—has been developed. This combination of optical and gamma cameras enables high spatial resolution multi-modal imaging, giving a superimposed scintigraphic and optical image. Hybrid imaging offers new possibilities for assisting clinicians and surgeons in localising the site of uptake in procedures such as sentinel node detection. The hybrid camera concept can be extended to a multimodal detector design which can offer stereoscopic images, depth estimation of gamma-emitting sources, and simultaneous gamma and fluorescence imaging. Recent improvements to the hybrid camera have been used to produce dual-modality images in both laboratory simulations and in the clinic. Hybrid imaging of a patient who underwent thyroid scintigraphy is reported. In addition, we present data which shows that the hybrid camera concept can be extended to estimate the position and depth of radionuclide distribution within an object and also report the first combined gamma and Near-Infrared (NIR) fluorescence images.

The 2π charged particles analyzer: All‐sky camera concept and development for space missions

AbstractIncreasing the temporal resolution and instant coverage of velocity space of space plasma measurements is one of the key issues for experimentalists. Today, the top‐hat plasma analyzer appears to be the favorite solution due to its relative simplicity and the possibility to extend its application by adding a mass‐analysis section and an electrostatic angular scanner. Similarly, great success has been achieved in MMS mission using such multiple top‐hat analyzers to achieve unprecedented temporal resolution. An instantaneous angular coverage of charged particles measurements is an alternative approach to pursuing the goal of high time resolution. This was done with 4‐D Fast Omnidirectional Nonscanning Energy Mass Analyzer and, to a lesser extent, by DYMIO instruments for Mars‐96 and with the Fast Imaging Plasma Spectrometer instrument for MErcury Surface, Space ENvironment, GEochemistry, and Ranging mission. In this paper we describe, along with precursors, a plasma analyzer with a 2π electrostatic mirror that was developed originally for the Phobos‐Soil mission with a follow‐up in the frame of the BepiColombo mission and is under development for future Russian missions. Different versions of instrument are discussed along with their advantages and drawbacks.

Feasibility study of a ``4H'' X-ray camera based on GaAs:Cr sensor

A multilayer stacked X-ray camera concept is described. This type of technology is called `4H' X-ray cameras, where 4H stands for high-Z (Z>30) sensor, high-resolution (less than 300 micron pixel pitch), high-speed (above 100 MHz), and high-energy (above 30 keV in photon energy). The components of the technology, similar to the popular two-dimensional (2D) hybrid pixelated array detectors, consists of GaAs:Cr sensors bonded to high-speed ASICs. 4H cameras based on GaAs also use integration mode of X-ray detection. The number of layers, on the order of ten, is smaller than an earlier configuration for single-photon-counting (SPC) mode of detection [1]. High-speed ASIC based on modification to the ePix family of ASIC is discussed. Applications in X-ray free electron lasers (XFELs), synchrotrons, medicine and non-destructive testing are possible.

Experimental Comparison of Knife-Edge and Multi-Parallel Slit Collimators for Prompt Gamma Imaging of Proton Pencil Beams

More and more camera concepts are being investigated to try and seize the opportunity of instantaneous range verification of proton therapy treatments offered by prompt gammas emitted along the proton tracks. Focusing on one-dimensional imaging with a passive collimator, the present study experimentally compared in combination with the first, clinically compatible, dedicated camera device the performances of instances of the two main options: a knife-edge slit (KES) and a multi-parallel slit (MPS) design. These two options were experimentally assessed in this specific context as they were previously demonstrated through analytical and numerical studies to allow similar performances in terms of Bragg peak retrieval precision and spatial resolution in a general context. Both collimators were prototyped according to the conclusions of Monte Carlo optimization studies under constraints of equal weight (40 mm tungsten alloy equivalent thickness) and of the specificities of the camera device under consideration (in particular 4 mm segmentation along beam axis and no time-of-flight discrimination, both of which less favorable to the MPS performance than to the KES one). Acquisitions of proton pencil beams of 100, 160, and 230 MeV in a PMMA target revealed that, in order to reach a given level of statistical precision on Bragg peak depth retrieval, the KES collimator requires only half the dose the present MPS collimator needs, making the KES collimator a preferred option for a compact camera device aimed at imaging only the Bragg peak position. On the other hand, the present MPS collimator proves more effective at retrieving the entrance of the beam in the target in the context of an extended camera device aimed at imaging the whole proton track within the patient.

INTRODUCTION OF A PHOTOGRAMMETRIC CAMERA SYSTEM FOR RPAS WITH HIGHLY ACCURATE GNSS/IMU INFORMATION FOR STANDARDIZED WORKFLOWS

Abstract. In this paper we present the evaluation of DLR’s modular airborne camera system MACS-Micro for remotely piloted aircraft system (RPAS) with a maximum takeoff weight (MTOW) less than 5kg. The main focus is on standardized calibration and test procedures as well as on standardized photogrammetric workflows as a proof of feasibility for this aerial camera concept. The prototype consists of an industrial grade frame imaging camera and a compact GNSS/IMU solution which are operated by an embedded PC. The camera has been calibrated pre- and post- flight using a three dimensional test field. The validation of the latest prototype is done by a traditional photogrammetric evaluation of an aerial survey using 39 ground control points. The results, concerning geometric and radiometric features of the present system concept as well as the quality of the aero triangulation, fulfill many of the aimed keyspecifications.

INTRODUCTION OF A PHOTOGRAMMETRIC CAMERA SYSTEM FOR RPAS WITH HIGHLY ACCURATE GNSS/IMU INFORMATION FOR STANDARDIZED WORKFLOWS

In this paper we present the evaluation of DLR’s modular airborne camera system MACS-Micro for remotely piloted aircraft system (RPAS) with a maximum takeoff weight (MTOW) less than 5kg. The main focus is on standardized calibration and test procedures as well as on standardized photogrammetric workflows as a proof of feasibility for this aerial camera concept. The prototype consists of an industrial grade frame imaging camera and a compact GNSS/IMU solution which are operated by an embedded PC. The camera has been calibrated pre- and post- flight using a three dimensional test field. The validation of the latest prototype is done by a traditional photogrammetric evaluation of an aerial survey using 39 ground control points. The results, concerning geometric and radiometric features of the present system concept as well as the quality of the aero triangulation, fulfill many of the aimed keyspecifications.

Temporal Imaging of Incoherent-Light Intensity Waveforms Based on a Gated Time-Lens System

We experimentally demonstrate temporal imaging of incoherent-light intensity waveforms using a combination of a temporal gating process and a time lens. This design allows one to set the system temporal field of view and resolution in an independent fashion, thus overcoming the intrinsic time–bandwidth product tradeoff of previous incoherent-light schemes based on the temporal pinhole camera concept. In a proof-of-concept experiment, we report incoherent-light temporal compression of intensity waveforms by a factor of 2.86, with a time–bandwidth product exceeding 300, i.e., resolution of ∼26 ps (approximately fourfold improvement over the corresponding pinhole-only design) along a temporal field of view of ∼8 ns, using a basic linear-optics setup.

Comparison of LSO and BGO block detectors for prompt gamma imaging in ion beam therapy

A major weakness of ion beam therapy is the lack of tools for verifying the particle range in clinical routine. The application of the Compton camera concept for the imaging of prompt gamma rays, a by-product of the irradiation correlated to the dose distribution, is a promising approach for range assessment and even three-dimensional in vivo dosimetry. Multiple position sensitive gamma ray detectors arranged in scatter and absorber planes, together with an imaging algorithm, are required to reconstruct the prompt gamma emission density map. Conventional block detectors deployed in Positron Emission Tomography (PET), which are based on Lu2SiO5:Ce (LSO) and Bi4Ge3O12 (BGO) scintillators, are suitable candidates for the absorber of a Compton camera due to their high density and absorption efficiency with respect to the prompt gamma energy range (several MeV). We compare experimentally LSO and BGO block detectors in clinical-like radiation fields in terms of energy, spatial and time resolution. The high energy range compensates for the low light yield of the BGO material and boosts significantly its performance compared to the PET scenario. Notwithstanding the overall superiority of LSO, BGO catches up in the field of prompt gamma imaging and can be considered as a competitive alternative to LSO for the absorber plane due to its lower price and the lack of intrinsic radioactivity.

The Temporal PET Camera: A New Concept With High Spatial and Timing Resolution for PET Imaging

This contribution proposes a new temporal PET camera concept yielding a precise spatio-temporal localization of a scintillation event within a monolithic scintillator. This concept is promising for PET imaging. The key idea behind this concept is the ability of the system to accurately localize the region of detected un-scattered photons on the Si-PMT detector plane. Then, by ray tracing, an accurate estimate of the depth and timing of the scintillation event is provided. An estimation of the potential performance of such a system, based on extensive Monte Carlo simulations, is also presented.

A new modality of bidimensional Compton camera.

The concept of Compton camera originates from the need to improve sensitivity in Single Photon Emission Imaging, which uses hole collimators. It advocates electronic collimation which registers radiation emitted by the radiating object and scattered by a scattering detector placed before an absorption detector. The data consists of three dimensional conical projections of the activity density of a radio-tracer. An analytic reconstruction method of this density is presently not available. To evaluate its imaging power, we consider a particular two-dimensional Compton camera in which the collected data consists of the set of integrals of the density on rotating V-lines. In this communication, we present simulation results obtained from an algebraic reconstruction technique, which illustrate and validate the imaging capability of this Compton camera modality.

Фотография в стоматологической практике

<p>In the practice of dentistry picture continues to gain new perspective and tends to expand in many new indications: as photo document; Dental portfolio; facilitates the relationship between doctors and laboratories; to explain to the patient the specific method of dental care; part of the record in court cases; marketing tool; promotional aspect; contact with insurance companies; research work; fixation unusual (exclusive clinical) cases or features of health care; for registration of the reporting documentation; Diagnostic photographs.</p><p>Fixing the dental status of the patient is carried out using a camera or intra-oral camera.</p><p> Select the type of camera is debatable aspect of this problem, especially in a legal matter.</p>The concept of intra-oral camera is used to inform, prepare documentation, improve inspection in complex cases, treatment of visibility when it is impossible to directly examine the working area

Single photon detection and localization accuracy with an ebCMOS camera

The CMOS sensor technologies evolve very fast and offer today very promising solutions to existing issues facing by imaging camera systems. CMOS sensors are very attractive for fast and sensitive imaging thanks to their low pixel noise (1e-) and their possibility of backside illumination. The ebCMOS group of IPNL has produced a camera system dedicated to Low Light Level detection and based on a 640 kPixels ebCMOS with its acquisition system. After reminding the principle of detection of an ebCMOS and the characteristics of our prototype, we confront our camera to other imaging systems. We compare the identification efficiency and the localization accuracy of a point source by four different photo-detection devices: the scientific CMOS (sCMOS), the Charge Coupled Device (CDD), the Electron Multiplying CCD (emCCD) and the Electron Bombarded CMOS (ebCMOS). Our ebCMOS camera is able to identify a single photon source in less than 10ms with a localization accuracy better than 1µm. We report as well efficiency measurement and the false positive identification of the ebCMOS camera by identifying more than hundreds of single photon sources in parallel. About 700 spots are identified with a detection efficiency higher than 90% and a false positive percentage lower than 5. With these measurements, we show that our target tracking algorithm can be implemented in real time at 500 frames per second under a photon flux of the order of 8000 photons per frame.These results demonstrate that the ebCMOS camera concept with its single photon detection and target tracking algorithm is one of the best devices for low light and fast applications such as bioluminescence imaging, quantum dots tracking or adaptive optics.

Recent progress of MPPC-based scintillation detectors in high precision X-ray and gamma-ray imaging

The multi-pixel photon counter (MPPC) is a promising light sensor for various applications, not only in physics experiments but also in nuclear medicine, industry, and even high-energy astrophysics. In this paper, we present the current status and most recent progress of the MPPC-based scintillation detectors, such as (1) a high-precision X-ray and gamma-ray spectral image sensor, (2) next-generation PET detectors with MRI, TOF, and DOI measurement capabilities, and (3) a compact gamma camera for environmental radiation surveys. We first present a new method of fabricating a Ce:GAGG scintillator plate (1 or 2mm thick) with ultra-fine resolution (0.2mm/pixel), cut using a dicing saw to create 50μm wide micro-grooves. When the plate is optically coupled with a large-area MPPC array, excellent spatial resolution of 0.48mm (FWHM) and energy resolution of 14% (FWHM) are obtained for 122keV gamma rays. Hence, the detector can act as a convenient “multi-color” imaging device that can potentially be used for future SPECT and photon-counting CT. We then show a prototype system for a high-resolution MPPC-based PET scanner that can realize ≃1mm (FWHM) spatial resolution, even under a strong magnetic field of 4.7T. We develop a front-end ASIC intended for future TOF-PET scanner with a 16-channel readout that achieves a coincidence time resolution of 489ps (FWHM). A novel design for a module with DOI-measurement capability for gamma rays is also presented by measuring the pulse height ratio of double-sided MPPCs coupled at both ends of scintillation crystal block. Finally, we present the concept of a two-plane Compton camera consisting of Ce:GAGG scintillator arrays coupled with thin MPPC arrays. As a result of the thin and compact features of the MPPC device, the camera not only achieves a small size (14×14×15cm3) and light weight (1.9kg) but also excellent sensitivity, compared to the conventional PMT-based pinhole camera used in Fukushima. Finally, we briefly describe a new product recently developed in conjunction with Hamamatsu Photonics K.K. that offers improved sensitivity and angular resolution of Δθ~8° (FWHM) at 662keV, by incorporating DOI-segmented scintillator arrays.

Compact camera for multispectral and conventional imaging based on patterned filters.

A multispectral camera concept is presented. The concept is based on using a patterned filter in the focal plane, combined with scanning of the field of view. The filter layout has stripes of different bandpass filters extending orthogonally to the scan direction. The pattern of filter stripes is such that all bands are sampled multiple times, while minimizing the total duration of the sampling of a given scene point. As a consequence, the filter needs only a small part of the area of an image sensor. The remaining area can be used for conventional 2D imaging. A demonstrator camera has been built with six bands in the visible and near infrared, as well as a panchromatic 2D imaging capability. Image recording and reconstruction is demonstrated, but the quality of image reconstruction is expected to be a main challenge for systems based on this concept. An important advantage is that the camera can potentially be made very compact, and also low cost. It is shown that under assumptions that are not unreasonable, the proposed camera concept can be much smaller than a conventional imaging spectrometer. In principle, it can be smaller in volume by a factor on the order of several hundred while collecting the same amount of light per multispectral band. This makes the proposed camera concept very interesting for small airborne platforms and other applications requiring compact spectral imagers.

Compressive holography with a single-pixel detector

This Letter develops a framework for digital holography at optical wavelengths by merging phase-shifting interferometry with single-pixel optical imaging based on compressive sensing. The field diffracted by an input object is sampled by Hadamard patterns with a liquid crystal spatial light modulator. The concept of a single-pixel camera is then adapted to perform interferometric imaging of the sampled diffraction pattern by using a Mach-Zehnder interferometer. Phase-shifting techniques together with the application of a backward light propagation algorithm allow the complex amplitude of the object under scrutiny to be resolved. A proof-of-concept experiment evaluating the phase distribution of an ophthalmic lens with compressive phase-shifting holography is provided.

Hemispherical Multiple Camera System for High Resolution Omni-Directional Light Field Imaging

Inspiration from light field imaging concepts has led to the construction of multi-aperture imaging systems. Using multiple cameras as individual apertures is a topic of high relevance in the light field imaging domain. The need for wide field-of-view (FOV) and high-resolution video for applications in areas of surveillance, robotics and automotive systems has driven the idea of omni-directional vision. Recently, the Panoptic camera concept has been presented that mimics the eyes of flying insects using multiple imagers. The Panoptic camera utilizes a novel methodology for constructing a spherically arranged wide FOV plenoptic imaging system whereas omni-directional image quality is limited by low resolution sensors. In this paper, a very-high resolution light field imaging and recording system inspired from the Panoptic approach is presented. Major challenges consisting of managing the huge amount of data as well as maintaining a scalable system are addressed. The proposed system is capable of recording omni-directional video at 30 fps with a resolution exceeding 9000 2400 pixels. The system is capable of capturing the surrounding light field in a FOV. This important feature opens the door to various post processing techniques such as quality-enhanced 3D cinematography, very high resolution depth map estimation and high dynamic-range applications which are beyond standard stitching and panorama generation.

A Gaseous Compton Camera using a 2D-sensitive gaseous photomultiplier for Nuclear Medical Imaging

A new Compton Camera (CC) concept based on a High Pressure Scintillation Chamber coupled to a position-sensitive Gaseous PhotoMultiplier for Nuclear Medical Imaging applications is proposed. The main goal of this work is to describe the development of a ϕ25×12cm3 cylindrical prototype, which will be suitable for scintimammography and for small-animal imaging applications. The possibility to scale it to an useful human size device is also in study. The idea is to develop a device capable to compete with the standard Anger Camera. Despite the large success of the Anger Camera, it still presents some limitations, such as: low position resolution and fair energy resolutions for 140keV. The CC arises a different solution as it provides information about the incoming photon direction, avoiding the use of a collimator, which is responsible for a huge reduction (10−4) of the sensitivity. The main problem of the CC's is related with the Doppler Broadening which is responsible for the loss of angular resolution. In this work, calculations for the Doppler Broadening in Xe, Ar, Ne and their mixtures are presented. Simulations of the detector performance together with discussion about the gas choice are also included .

Mixel camera––a new push-broom camera concept for high spatial resolution keystone-free hyperspectral imaging

Current high-resolution push-broom hyperspectral cameras introduce keystone errors to the captured data. Efforts to correct these errors in hardware severely limit the optical design, in particular with respect to light throughput and spatial resolution, while at the same time the residual keystone often remains large. The mixel camera solves this problem by combining a hardware component--an array of light mixing chambers--with a mathematical method that restores the hyperspectral data to its keystone-free form, based on the data that was recorded onto the sensor with large keystone. A Virtual Camera software, that was developed specifically for this purpose, was used to compare the performance of the mixel camera to traditional cameras that correct keystone in hardware. The mixel camera can collect at least four times more light than most current high-resolution hyperspectral cameras, and simulations have shown that the mixel camera will be photon-noise limited--even in bright light--with a significantly improved signal-to-noise ratio compared to traditional cameras. A prototype has been built and is being tested.

The Flutter Shutter Paradox

Photography is the art of acquiring as many photons as possible of a given scene. In classic cameras, the aperture time is irremediably limited by the risk of a motion blur when the camera and the scene are in relative motion. Nevertheless, two recent camera concepts, the Agrawal et al. flutter shutter and the Levin et al. motion-invariant photography permit one to extend indefinitely the exposure time while guaranteeing an invertible motion blur. In this paper, a complete mathematical theory of these new technologies is proposed. Modeling the capture noise, the theory furnishes explicit formulas for the signal to noise ratio $(SNR)$ of the final image after deconvolution when the motion is uniform. It puts in evidence the existence of two variants, the analog flutter shutter and the numerical flutter shutter. The results of the resulting quantitative comparison are slightly paradoxical. First, it is shown that the best camera aperture strategies are always flutter shutters, even when the aperture time is a priori fixed. Second, it is shown that the $SNR$ increase obtained by using a flutter shutter in the presence of a known motion remains bounded, even with an infinite exposure time. Incidentally, the theory gives the formula of the optimal classic snapshot in the presence of motion and compares its performance to the optimal flutter shutter.