High-resolution CCD Camera Research Articles

A light-efficient and versatile multiplexing method for snapshot spectral imaging

The study of rapid and stochastic events that involve multiple species, such as chemical reactions and plasma dynamics, requires means to capture multispectral information in two dimensions at both high temporal- and spatial resolution. Commercially available cameras that provide high temporal resolution are based on either signal intensification or rapid data acquisition. Intensified cameras provide extremely short acquisition times using intensification by means of micro channel plates, but the conversion between electrons and photons makes these cameras inherently monochrome. In contrast, high-speed cameras can achieve color-sensitivity through integrated Bayer filters but suffer from a reduced light collection efficiency and a fixed spectral composition. In this article we present a non-integrated optical arrangement for instantaneous multispectral imaging based on FRAME image multiplexing. By spectrally separating the signal using lossless dichroic mirrors, a 16-fold increase in light-collection efficiency is gained (compared to past solutions), resulting in an equivalent increase in temporal resolution. This improvement provides new avenues for multispectral imaging of rapid events. We demonstrate the system’s versatility and suitability for studies of such processes by applying it for (i) temperature mapping using a high-resolution CCD camera, (ii) high-speed videography up to 10 kHz at four spectral channels and (iii) dual-species visualization in a plasma discharge using an intensified sCMOS camera.

Contrastive Analysis of Interferometric Techniques for Small Channel Temperature Measurements

This research employs a state-of-the-art digital interferometric technique to investigate the temperature distribution within a confined rectangular channel, with a hydraulic diameter of 3 mm. The experimental setup incorporates an optical glass channel, with nanofluids (Aluminium oxide) as the test fluid at 0.001% volume concentration. To induce controlled heating, a heater filament is strategically placed along the bottom wall of the channel. Simultaneously, a T-type thermocouple is carefully placed to measure the temperature along the upper wall. Two distinct interferometric methods, namely the Michelson interferometer and the Mach-Zehnder interferometer, are employed to capture the complex details of fringes resulting from the evolving temperature field within the test section. A high-resolution CCD camera is employed to capture these fringes, and sophisticated digital image processing techniques are subsequently applied for in-depth fringe analysis. The culmination of these efforts results in the origin of a comprehensive localized temperature distribution map within the small-sized channel. The obtained temperature profiles are meticulously compared, providing valuable insights into the effectiveness and reliability of the Michelson and Mach-Zehnder interferometric techniques in this specific experimental context. This detailed comparative analysis contributes to the broader understanding of interferometric methods for temperature measurements in confined fluidic systems.

Investigation of renal calculi fragmented tracer particles in lithotripsy model by laser speckle technique

We have developed a laser sheet method to evaluate micro-sized fragmented calcium oxalate granular particles created kidney stones suspended in a Newtonian fluid in an in vitro model. These tracer particles are examined by laser optical techniques. An optical setup is configured with a laser sheet to conduct image velocimetry on these calcium oxalate seed particles in the urine environment. The experimental setup involves the application of ultrasonic waves to fragment the calcium oxalate tiny stones of varying sizes and disperse them in random directions in the fluid. The data acquisition process employs double frame-single exposure imaging, which captures images at specified time intervals using a high-resolution CCD camera. This provides information regarding particle displacement and track the flow path within the Newtonian fluid. In addition, the bigger fragmented particles are identified, and their sizes are also measured.

Study on CO2* chemiluminescence of CH4/O2 co-flow diffusion flame based on the chemical kinetic mechanism

Chemiluminescence of CO2* is suitable for characterizing flame properties such as flame structure, equivalence ratio and heat release rate. However, experimental studies and numerical simulations of CO2* are not yet complete. In this work, the two-dimensional distributions of CO2* chemiluminescence were obtained by a high-resolution CCD camera. Numerical simulation results of CO2* were performed based on the detailed reaction kinetics mechanism of CO2* and were in good agreement with that of experiments. The differences of CO2* reactions at different axial positions were studied. The main CO2* formation reaction R2(CH + O2 = CO2*+H) at the burner outlet and R1(O + CO + M = CO2*+M) at the core reaction zone were determined. On the fuel side, the R1 reaction rate was mainly affected by temperature. On the oxidizer side, the R1 reaction rate was affected by temperature and reactant mole fraction. The main quenching reaction was R5(CO2*+H2O = CO2 + H2O). The oxygen-fuel equivalence ratio changed the reaction rate of formation and quenching reactions mainly by affecting temperature and reactant mole fraction.

B-PO05-081 SIMULTANEOUS ULTRA-HIGH RESOLUTION OPTICAL MAPPING AND CATHETER MAPPING IN A LANGENDORFF-PERFUSED SWINE HEART MODEL TO IDENTIFY ATRIAL FIBRILLATION ROTORS BY CATHETER MAPPING

The accuracy of atrial fibrillation (AF) rotor identification by catheter mapping (CM) has not been validated. To obtain simultaneous ultra-high resolution optical mapping (OM) and high resolution CM during AF in a Langendorff perfused swine heart model to test the feasibility of identifying AF rotors by CM. Langendorff preparation was performed in 3 swine. The isolated heart was stained with a voltage-sensitive dye, illuminated by LED. Two high resolution CCD cameras (26,624 pixels, each) simultaneously recorded fluorescence from the RA and LA free-wall (spatial resolution <0.1mm). Two mapping catheters (48 electrodes, 2 mm spacing, and one central non-contact reference electrode for close unipolar EGMs, OCTARAY, Biosense Webster, Fig) was sutured on the RA and LA, covering 3x3 cm area, respectively (total 96 close unipolar EGMs). An anatomical shell of RA and LA was formed using the CARTO3 system. AF was induced by rapid atrial pacing during atrial stretch. Optical signals (membrane potential map and phase map) and catheter epicardial atrial EGMs (AF activation map) were recorded simultaneously during AF. (Fig.) During AF, OM identified stable and/or unstable rotors in all 14 AF episodes (all 3 swine), often located at the base of RA or LA appendage. Compared to unstable rotors, stable rotors had shorter cycle length (median 105 ms vs 114 ms, p<0.05). CM identified corresponding rotational activities (spiral reentry) when the rotor was located close to the center of the electrodes. There was no false positive rotor detection by CM. Close unipolar CM identifies AF rotors, but only when rotor centers are located within the mapping area.

3D flow structures behind a wall-mounted short cylinder

A high-resolution Tomographic particle image velocimetry (Tomo-PIV), which consists of four high-resolution double-exposure CCD cameras, was used to measured three-dimensional (3D) flow structures behind a wall-mounted short cylinder of an aspect ratio 1 at Reynolds number 10,720 in a water tunnel. Based on the measured instantaneous 3D velocity distribution, 3D velocity fields, the vorticity, the Q criterion, the rear separation region and the characteristic of arch type vortex and tip vortices are first discussed. In order to evaluate 3D multi-scale wake flow structures and energetic flow structures, the 3D orthogonal wavelet multi-resolution technique and proper orthogonal decomposition (POD) are applied to analyze instantaneous 3D velocity fields of Tomo-PIV. A 3D W-type arch vortex behind the short cylinder is found, which is originated by the interaction between upwash and downwash flows. The head shape of arch vortex structure is associated with the aspect ratio of the cylinder. By using the 3D orthogonal wavelet multi-resolution analysis, the instantaneous arch vortex and streamwise vortices are extracted in the large-scale structures of the wavelet level 1. It also found that the intermediate-scale upwash flows play an important role in originating the head of W-type arch vortex. Strong small-scale structures appeared in the shear layer and were contained in the intermediate-scale structures. The POD analysis indicates that the first two modes account for 13.3% of the total turbulent fluctuating energy, and the first four POD modes exhibit several large-scale streamwise vortices.

New neutron imaging facility at the WWR-SM reactor: Design and first results

The goal of this article is to describe the new neutron imaging facility constructed on the 5th radial beamline of the WWR-SM research reactor at the Institute of Nuclear Physics of the Academy of Sciences of the Republic of Uzbekistan (Tashkent, Republic of Uzbekistan). The neutron beam with the dimensions of 90 × 90 mm2 is formed by the collimator system, the characteristic parameter L/D is 600. The two mirror detector system is based on the 6LiF/Zn(Cd)S:Ag scintillation screen and the high-resolution ProLine PL-09000 CCD camera. The design of the experimental facility, the main parameters, and recently obtained results of the neutron radiography and tomography experiments are presented.

High-resolution Three-dimensional Surface Imaging Microscope Based on Digital Fringe Projection Technique

Abstract The three-dimensional (3-D) micro-scale surface imaging system based on the digital fringe projection technique for the assessments of microfiber and metric screw is presented in this paper. The proposed system comprises a digital light processing (DLP) projector, a set of optical lenses, a microscope, and a charge coupled device (CCD). The digital seven-step fringe patterns from the DLP projector pass through a set of optical lenses before being focused on the target surface. A set of optical lenses is designed for adjustment and size coupling of fringe patterns. A high-resolution CCD camera is employed to picture these distorted fringe patterns. The wrapped phase map is calculated by seven-step phase-shifting calculation from these distorted fringe patterns. The unwrapping calculation with quality guided path is introduced to compute the absolute phase values. The dimensional calibration methods are used to acquire the transformation between real 3-D shape and the absolute phase value. The capability of complex surface measurement for our system is demonstrated by using ISO standard screw M1.6. The experimental results for microfiber with 3 μm diameter indicate that the spatial and vertical resolutions can reach about 3 μm in our system. The proposed system provides a fast digital imaging system to examine the surface features with high-resolution for automatic optical inspection industry.

Optical anisotropy measurement in normal and cancerous tissues: backscattering technique.

Investigating the deformation of tissue architecture is one of the most important clinical methods for cancer diagnosis. Optical methods are now widely developed for rapid, precise, and real-time assessment of these alterations at the microscopic scale. One of the proposed methods is enhanced backscattering (EBS) technique that allows in-vivo measurement of the optical scattering characteristics. Here, EBS technique is employed to evaluate the optical anisotropy of human epithelial tissues as a measure to distinguish between normal and cancerous one. Orientation dependence of the mean scattering length is assessed in healthy and cancerous tissues of five different human organs i. e. uterus, bladder, colon, kidney, and liver. Helicity preserving channel and rotating ground glass diffuser are utilized to eliminate the polarization induced anisotropy and the background speckle noises respectively. Analysis of the backscattering cones recorded by a high-resolution CCD camera reveals the modification of the strength and degree of optical anisotropy in different tissues during cancer progression. Pathology data affirm the correlation between the experimental results and the morphological alteration of the epithelial cells in each carcinoma type. In general, tissues with fibrous constructional cells are subject to a decrease in anisotropy due to cancer, whereas those with cuboidal cells experience an increase in anisotropy. This complementary information enhances the potency of the EBS technique as a fast, non-destructive, and easily accessible tool for real-time tissue diagnosis.

High-Temperature Interaction of Molten Gray Cast Iron with Al2O3-ZrO2-SiO2 Ceramic

High-temperature interaction between molten conventional gray cast iron (wt.%: 4.1 C; 1 Si; 0.20 Mn; 0.03 S; 0.04 P, the rest—Fe) and multiphase Al2O3-ZrO2-SiO2 ceramic substrate (wt.%: 51.5 Al2O3, 33.8 ZrO2, 13.3 SiO2, ~ 1 NaO2, 0.15 Fe2O3 + TiO2 + CaO) was examined at a temperature of 1450 °C for 15 min under inert flowing gas atmosphere (Ar, 850-900 hPa) using a sessile drop method coupled with contact heating procedure. Melting, wetting behavior and solidification of gray cast iron sample were continuously recorded with a high-speed high-resolution CCD camera. Under conditions of this study, selected gray cast iron alloy does not wet the Al2O3-ZrO2-SiO2 ceramic forming the final contact angle with average value of θf ~ 135°. The wetting kinetic curve was not smooth and its shape suggests the effect of substrate chemical heterogeneity due to multiphase composition of the substrate material. After the sessile drop test, the solidified drop was easily detached from the ceramic substrate along the drop-side interface showing a lack of bonding between the drop and the substrate. Structural characterization of the drop/substrate couple evidenced the nucleation and growth of graphite at the drop surface and at the drop/substrate interface taken place during solidification and resulting into the formation of discontinuous interfacial graphite layer.

Resolution limits of a single crystal scintillator based X-ray micro-radiography camera

Recently, high resolution micro-radiography became of great interest. Very thin scintillator layers of about 5–20 micrometres are used to achieve spatial resolution below one micrometre in application for low energy X-ray micro-radiography [1]. Such thin screens are mainly used in micro-XCT and nano-XCT systems (X-ray Computed Tomography) with either micro-focus X-ray tubes or with synchrotron sources [2]. This work deals with a high-resolution CCD camera together with different optical systems and different single crystal scintillators in application for low energy X-ray micro-radiography. The light distribution on the screen is re-imaged by an optical system (usually represented by classical microscope objective together with a field lens) to a high-resolution CCD or CMOS chip. A theoretical modelling and practical comparison of a camera set-up has been done to investigate the system resolution limits. Thin screens were prepared from YAG:Ce scintillator. The resolution is presented on test patterns. As recent optical systems are limited to the classical microscopy objectives only, we further investigate a possibility to develop a custom-made objective fully dedicated to X-ray imaging application.

Design of a high frame rate driver circuit for a 22 M-pixel high-resolution large-area array CCD camera and its nonuniformity correction

When using a high-resolution full-frame area array charge-coupled device (CCD) FTF4052M as the aerial image sensor of a camera, the frame rate is generally below 1 frame / second (fps), which cannot meet the requirements of applications with high frame rates. First, the FTF4052M drive circuit is introduced. Next, an improved driver circuit of the CCD 4052M is proposed. Using the CCD to output four amplifiers simultaneously yielded a maximum frame rate of 3.4 fps. Then, the timing of the CCD driver, the front-end processing circuit, the DC bias circuit, and the interface circuit of the four outputs are designed. The improved driver circuit could meet the application requirements of various aerial cameras. In addition, the FTF4052M nonuniformity is analyzed, and a nonuniformity response detection system is established. Using this system, the FTF4052M array’s nonuniformity among the four quadrants and among the pixels is tested. Based on the CCD’s linear responsivity, two correction algorithms are proposed to correct the nonuniformity. Finally, using the correction, the four quadrants’ standard deviations of the response sensitivity are reduced by a factor of 1 / 13, and the responsive nonuniformity among all pixels is reduced by a factor of 1 / 10. Through the reshooting of the identified rate board, it is found that the nonuniformity of the CCD array is markedly improved.

License Plate Detection and Facial Analysis Using TensorFlow Deep Learning Algorithm

Nowadays license plate recognition has been applied in car access control, toll collection and other applications. Even though they exist, car thefts and illegal use of other proprietor’s license plate remain a problem. To deal with this, a computational programmed controlled framework is being developed. Also, facial analysis algorithm is implemented so as to create awareness among the common public. The way forward is to use an improved technology combination of License Plate Detection and Facial Analysis using artificial intelligence, in which vehicle image is captured by high resolution CCD camera and the license plate region is determined by image processing algorithms and facial analysis is done by using FaceNet and TensorFlow. The characters of the license plate is separated by segmentation and processed using the Canny Edge and Blob Coloring algorithm and the facial analysis is done using Facenet of TensorFlow.

High-Temperature Interaction of Liquid Gd with Y2O3

The sessile drop method combined with contact heating procedure was applied for the investigation of high-temperature interaction between liquid Gd and Y2O3 substrate. Real-time behavior of Gd sample in flowing inert gas (Ar) atmosphere upon heating to and at temperature of 1362 °C was recorded using high-speed high-resolution CCD camera. The results evidenced that molten Gd wets Y2O3 substrate (the contact angle θ < 90°) immediately after melting of metal sample observed at T = 1324 °C (Tm = 1312 °C). During the first 3 min of the sessile drop test, the contact angle dropped from θ = 52° to θ = 24° and then stabilized at the final value of θf* = 33°. The solidified Gd/Y2O3 couple was subjected to structural characterization using optical microscopy, scanning electron microscopy coupled with x-ray energy-dispersive spectroscopy. The results evidenced that the wettability in the Gd/Y2O3 system has a reactive nature and the leading mechanism of the interaction between liquid Gd and Y2O3 is the dissolution of the ceramic in the liquid metal responsible for the formation of a deep crater in the substrate under the drop. Therefore, the final contact angle θf*, estimated from the side-view drop image, should be considered as an apparent value, compared to the more reliable value of θf = 70° measured on the cross section of the solidified couple.

Uniaxial compression of calcite single crystals at room temperature: insights into twinning activation and development

Abstract. E-twinning is a common plastic deformation mechanism in calcite deformed at low temperature. Strain rate, temperature and confining pressure have negligible effects on twinning activation which is mainly dependent on differential stress. The critical resolved shear stress (CRSS) required for twinning activation is dependent on grain size and strain hardening. This CRSS value may obey the Hall–Petch relation, but due to sparse experimental data its actual evolution with grain size and strain still remains a matter of debate. In order to provide additional constraints on twinning activation and development, new mechanical tests were carried out at room temperature on unconfined single crystals of calcite, with different sizes and crystallographic orientations. Uniaxial deformation was performed at a controlled displacement rate, while the sample surface was monitored using optical microscopy and a high-resolution CCD (charge-coupled device) camera. The retrieved macroscopic stress–strain behavior of the crystals was correlated with the surface observations of the deformation process. Results show (1) the onset of crystal plasticity with the activation of the first isolated mechanical twins during the strain hardening stage, and (2) the densification and thickening of twin lamellae during the steady-state flow stress stage. Such thickening of twin lamellae at room temperature emphasizes that calcite twin morphology is not controlled solely by temperature. The different values for the CRSS obtained for the activation of isolated twins and for the onset of twin densification and thickening raises questions regarding the appropriate value to be considered when using calcite twin data for stress inversion purposes.

Void fraction measurement using an imaging and phase isolation method in horizontal annular flow

A new imaging method was proposed to measure the void fraction of annular flow based on phase isolation technology in a horizontal circular tube. As the gas–liquid mixture passes through the phase isolation device, which is arranged upstream, a strong swirl flow is created due to centrifugal effect. The liquid phase is pushed to the tube wall and forms a uniform liquid film, while the gas phase is concentrated to the tube center and forms a gas core. This rectified core-annular flow has a more smooth and clear phase interface than that of natural annular flow, which makes the accurate measurement of some inherent flow parameters of gas–liquid two-phase flow possible and much easier to perform. A backlight-collimated illumination and high-resolution CCD camera were employed to capture the gas core and liquid film. A calibration experiment was conducted to acquire an accurate edge detection criterion for recognition of the phase interface. The morphological image characteristics of the core-annular flow and the beam path diagram of imaging procedure were analyzed in detail and a corresponding image processing algorithm was developed. The working fluids were air and water and the ranges of void fraction covered in the sexperiment were 0.736–0.978(Usg = 4.35 m s−1–39.12 m s−1, Usl = 0.016 m s−1–0.504 m s−1). For each experiment condition, about 800 raw images were processed to obtain an average result. Comparisons to a representative model of void fraction of natural annular flow showed that the void fraction of the core-annular flow rectified by the phase isolation device remains well consistent with that of natural annular flow in the range of low-gas volume fraction, while the void fraction of core-annular flow becomes a little lower than that of natural annular flow as the gas volume becomes very high.

Gamma beam collimation system and profile imager for ELI-NP

ELI-NP-GBS is a high-brilliance gamma source that will produce monochromatic beams in the energy range 0.2–19.5 MeV through inverse Compton scattering . In order to obtain a monochromatic beam a collimation of the emission is necessary. Depending on the energy, the angular aperture required to provide the design bandwidth Δ E/E=0.5% is between 70 and 700 μ rad. This collimation is provided by a stack of 14 tungsten slits, arranged with a relative rotation around the beam axis, so that the overlap will be a continuously adjustable aperture. To monitor the operation and alignment of the collimation, a set of detectors will provide a complete characterization of the gamma beam, including the measurement of the transverse spatial distribution. For this task a gamma beam profile imager based on a thin scintillator screen and a high-resolution CCD-camera was developed. In this work we briefly present the status of the collimation system and beam profile imager, which were designed, assembled and are currently under test at INFN-Ferrara laboratories.

Time-of-Flight Sensor in a Book Reader System Design for Persons With Visual Impairment and Blindness

This paper integrates a time-of-flight (ToF) sensor to a high-resolution charge-coupled device camera in a new and fully automated book reader design for individuals with visual impairment and blindness. This cost-effective and portable book reader design integrates, in a unique way, a 3-D map extracted by a low-resolution ToF sensor and a high-resolution image as means to correct the page curvature of bound books. This is achieved by a seamless registration process of two imaging modalities, so that the low-resolution ( $160 \times 120$ pixels) depth map accurately reflects the entire book spread as captured by the high-resolution camera ( $3072 \times 2304$ pixels). As part of the automated registration process, the book reader will give the user a warning message if the book is misplaced within its field of view. The reading accuracy is further improved by a mathematical framework formulating the flattening and extension operations, which together optimally dewarp the book spread images. This correction process is resilient to potential misplacement of the book within the book reader platform. The testing phase led to a reading accuracy of over 95%, involving an unprecedented acquisition and processing of 200 pages. A database consisting of all the 200 high-resolution book spread images together with their respective extracted depth maps are made available to the research community for further developments.

A versatile facility for investigating field-dependent and mechanical properties of superconducting wires and tapes under cryogenic-electro-magnetic multifields.

To investigate the field-dependent and mechanical properties of superconducting wires and tapes as a function of cryogenic temperature, transport current, and magnetic field, we designed and constructed a versatile facility capable of providing cryogenic-electro-magnetic multifields. The facility comprises several relatively independent systems to acquire multiple fields and explore various properties for superconductors. A superconducting racetrack magnet is manufactured to generate a transverse background field up to 3.5 T in a relatively large space of a homogeneous region of ∅200 mm × H 150 mm. A cryogenic system consisting of a vacuum Dewar vessel with a visible window cooled by two Gifford-McMahon (GM) cryocoolers for providing refrigeration was built to accommodate the background magnet and testing devices, in which one GM cryocooler cools the magnet at an operation temperature of about 4 K and the other maintains a cryogenic environment for specimens in conduction mode with the cryocooler head directly contacting the fixtures. The continuous variations of temperature (4-293 K) and transport current (0-1000 A) in the superconducting wires and tapes that were tested are, respectively, implemented by an integration differentiation temperature control with an optional temperature sweep rate and a DC high-power supply. Most prominently, the facility can measure the field-dependent and mechanical properties for superconducting wires and tapes, which is implemented by a mechanical loading and measuring system equipped with a universal testing machine possessing a specific design of widening and heightening size and a noncontact digital image correlation method with a high-speed, high-resolution CCD camera for real-time recording and full-field deformation of specimens. The preliminary results of tests verify the multifield functionalities of the versatile facility and illustrate the performance of the facility for studying the properties of superconducting wires and tapes as a function of magnetic field, cryogenic temperature, transport current, and mechanical loading.

Interaction Between Liquid Silver and Graphene-Coated SiC Substrate

Wettability between liquid Ag and graphene-coated SiC single crystal has been investigated by dispensed drop method at T = 970 °C under vacuum accompanied with subsecond recording of the drop/substrate images (100 frames per second) by high-speed high-resolution CCD camera. Non-contact heating method coupled with capillary purification of the Ag drop procedure has been applied. Scanning electron microscopy combined with EDS analysis and scanning probe microscopy combined with Raman spectroscopy techniques has been utilized for microstructure and surface characterization of samples before and after high-temperature wetting tests. Immediately after its detachment from the capillary, the Ag drop showed non-wetting behavior (θ > 90°) forming a high contact angle of θ = 114°. Surface characterization of the drop surface after wettability tests evidenced the presence of graphene and Si transferred from the substrate to the top of Ag drop. These findings suggest chemical interaction phenomena occurring at the interface. Locally, an intimate contact between liquid Ag and SiC substrate was allowed by the appearance of discontinuities in the graphene layer basically produced by thermomechanical stress. Local dissolution of carbon into liquid Ag and its reorganization (by segregation, nucleation and growth) as secondary graphene layer at the Ag surface was also observed.