Charge-coupled Device Research Articles

Novel RFID Multi-Label Network Location Measurement by Dual CCD and Non-Local Means–Harris Algorithm

To improve the performance of Radio Frequency Identification (RFID) multi-label systems, the multi-label network structure needs to be quickly located and optimized. A multi-label location measurement method based on the NLM–Harris algorithm is proposed in this paper. Firstly, multi-label geometric distribution images are obtained through a label image acquisition system of a multi-label semi-physical simulation platform with two vertical Charge-Coupled Device (CCD) cameras, and Gaussian noise is added to the image to simulate thermoelectric interference. Then, a fast NLM algorithm that optimizes the kernel coefficient acquisition speed is used for image denoising. Finally, the Harris corner algorithm is used to obtain the corner points of the images. After screening the diagonal points, the pixel coordinates of the preset origin and the four corners of the labels are obtained. Furthermore, the actual coordinates of the labels are obtained according to the pixel relationship. The results show that the average absolute errors of x, y, and z coordinates are 0.773 mm, 0.782 mm, and 0.807 mm, respectively. In addition, the relative errors are 1.659%, 2.260%, and 0.258%, which shows the high location accuracy of the multi-label network. It is of great significance to measure and optimize the performance of multi-label systems.

PROSTATE CANCER DIAGNOSTICS MODELING USING THE INFRARED IMAGING METHOD.

Imaging plays an important role in the identification of prostate cancer (PCa). However, a shortcoming of the current imaging techniques is their inability to detect PCa at an early stage of development when tumor volume is small. This led us to explore new and improved imaging methods. The phenomenon that infrared (IR) light penetrates biological tissues caused our efforts to utilize IR rays for PCa visualization. The aim of this study was to conduct model experiments to demonstrate how IR light could be used in the future to detect PCa in vivo. Experiments were carried out on prostates obtained after radical prostatectomy. The study was approved by the ethical commission of the Georgia-Israel Joint Clinic "Gidmedi". We developed a device that uses IR light to illuminate a prostate from the inside. In order to get IR images of the prostate, we developed a device with an IR-sensitive charge-coupled device (CCD) camera. The model experiments showed that the intensity of IR light passing through noncancerous and malignant prostate tissues is significantly different allowing their distinguishment. The visualization device can detect PCa lesions as small as several millimeters. These results suggest that our device could be useful for the detection of small PCa lesions.

Study on discharge characteristics of low-temperature sub-atmospheric pressure under steep change rate voltage

Aiming at the gas discharge problem in electric aircraft, this work studies the gas discharge characteristics at low-temperature sub-atmospheric pressure. A gas discharge shooting platform was built, and the discharge process was photographed by intensified charge-coupled device (ICCD). A two-dimensional axisymmetric model of needle-plate electrode gas discharge was established, and three sets of Helmholtz equations were used to solve the photoionization. The results show that under the same voltage, the electric field intensity in the discharge process increases first, then decreases and finally increases again. The discharge speed increases with the increase of altitude, and the electron density in the streamer decreases with the increase of altitude. The development speed of the streamer in the middle stage is higher than that in the early stage, and the speed increases more obviously with the increase of altitude. The development speed of the streamer in the later stage is lower than that in the middle stage, but with the increase of altitude, the development speed of the streamer in the later stage is higher than that in the middle stage.

Luminescent Tactile Sensor System for Robots: Enhancing Human-Computer Interaction in Complex Dark Environments.

In order to achieve interaction and collaboration with humans, robots need to have the ability for tactile perception of simulating human. Traditional methods use electrically connected sensors with complex arrays, leading to intricate wiring, high manufacturing costs, and demanding current environments. A flexible sensor with simple structure, easy preparation process, and low cost based on triboluminescence effect is proposed in this paper, which avoids the complex array and wiring of traditional sensors. The study discusses the relationship between luminescent intensity and factors such as luminescent particle content, luminescent layer thickness, encapsulation layer thickness, and friction layer thickness. It also analyzes the mechanism of luminescence. A micro charge-coupled device is configured for the luminescent unit to collect optical information and is integrated with the robot's manipulator for testing. A simple sensing system is constructed to demonstrate environmental perception, acquiring, and feeding back shape and size information of contact objects in the dark. The system successfully identifies and judges target objects in complex dark environments, offering insights for applications such as unmanned assembly lines. It overcomes the challenge of intricate electrical connections, paving new avenues for intelligent object recognition research in human-computer interaction.

Long-term properties of coronal off-limb structures

Extracting plasma structures in the solar corona (e.g. jets, loops, prominences) from spacecraft imagery data is essential in order to ascertain their unique properties and for our understanding of their evolution. Hence, our aim is to detect all coronal off-limb structures over a solar cycle and to analyse their statistical properties. In particular, we investigated the intensity and density evolution of these coronal structures, with a specific focus on active longitudes in the corona, that is, longitudinal regions where the solar activity is unequivocally dominant. We developed a methodology based on mathematical morphology (MM) algorithms to extract these coronal structures from extreme ultraviolet (EUV) images taken by the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) in the 304 wavelength channel during Solar Cycle (SC) 24. The resulting dataset consists of $877,843$ structures spanning the whole period from June 2010 to December 2021 with a three-hour cadence. We assessed the main characteristics of these coronal off-limb structures, such as their length, width, area, perimeter, latitude, and longitude (evaluated at the centre of the structures), as well as their intensity corrected for the charge-coupled device (CCD) sensitivity degradation of the AIA instrument. Regarding most of these properties, we find similar trends to the behaviour of the on-disk features, including the butterfly diagram and the structures that migrate towards the polar regions (also referred to as `rush-to-the-poles' structures) expanding during the rising phase of SC 24 until the reversal of the magnetic field at the solar poles. We uncover an interesting distribution: lower-intensity coronal structures seem to behave differently with respect to higher-intensity structures. The butterfly diagram is clearly shaped by the high-intensity structures, while the lower-intensity structures are more dispersed and survive during the declining phase of SC 24. We also find evidence of the existence of active longitudes in the corona and of their dependence on differential rotation and latitude.

DNA Hybridization Kinetics Observed at the Single-Molecule Level Using Graphene Near-Field Effects.

We present the development of an advanced sensing platform using a monolayer of graphene functionalized with fluorophore-labeled DNA hairpins to detect the kinetics of single hairpins during the hybridization reaction. The near-field photonic effects of graphene induce a distance-dependent quenching effect on the attached fluorescent labels, resulting in distinct optical signals in response to axial displacements resulting from DNA hybridization. Employing a wide-field Total Internal Reflection Fluorescence (TIRF) optical setup coupled with a sensitive Electron-Multiplying Charge-Coupled Device (EM-CCD) camera, we successfully detected fluorescent signals of individual or a low number of individual DNA hairpins within a low-concentration environment DNA target (tDNA). These signals were used to determine the optical setup's Point Spread Function (PSF) in a novel approach to super-resolution reconstruction. Combining these techniques, the subpixel localization of single hairpin molecules and their respective intensity profiles were extracted, enabling a kinetic assessment of individual DNA hairpins, with estimated unfolding times of approximately 7 s. Observations of kinetic phenomena unveiled intermediate partially hybridized states, extending the time required to unfold the hairpin probes by more than a factor of 2. Furthermore, a developed semiempirical model allowed the conversion of fluorescent signals into fluorophore-graphene distances. At the nanometer scale, we observed a step-like unfolding process characterized by intermittent metastates of unfolding and static periods, which can be attributed to nucleation events in some cases. Our graphene-based sensing platform and optical methodologies can be adopted for further research into the kinetics of different biomolecules under diverse environmental conditions.

Intelligent calibration of dual liner CCD intersection testing system based on Backpropagation neural network

Abstract In order to improve the measurement accuracy and calibration efficiency of the dual liner Charge Couple Device (CCD) intersection measurement system, a calibration technique based on Backpropagation (BP) neural network is proposed. This calibration method does not consider the parameters of the linear CCD camera and treats the entire dual liner CCD intersection measurement system as a whole for calibration. In the testing of the dual liner CCD intersection measurement system, the pixel coordinates of the measured target in the pixel plane of the linear CCD camera will change with the actual position of the measured target. The position of the measured target is continuously changed multiple times to construct a training sample set. The BP neural network is trained using the constructed training samples, and the strong nonlinear mapping ability of the BP neural network is utilized to obtain the mapping relationship between the pixel coordinates of the measured target and the actual coordinates of the measured target in the dual liner CCD intersection measurement system. A dual liner CCD intersection measurement system was constructed, and calibration experiments were designed to compare and analyse the experimental data. The results show that the proposed method can improve the testing accuracy and stability of the dual liner CCD intersection measurement system, while also improving calibration efficiency.

Streamer propagation in CO2 and N2/CO2 mixtures at atmospheric pressure

Abstract This study investigated streamer discharge in CO₂ and N2/CO2 mixtures. Experiments were conducted at atmospheric pressure and room temperature conditions by using a point-to-plane electrode configuration. A repetitive pulse discharge at 50 Hz was used to stabilise the discharge in CO₂. Under these conditions, the discharge current and intensified charge-coupled device (ICCD) camera images were systematically analysed during streamer evolution in CO2. The results revealed that streamer propagation and electrical properties were considerably influenced by the N₂ concentration in CO₂. Analysis of the emission of secondary streamers indicated that the emission ratio of primary streamers and secondary streamers in CO2 differed considerably from that in air. The onset delay time of streamer discharge was measured and statistically processed based on previous studies of streamer onset processes. Findings indicated an increase in the discharge delay time and its dispersion when N₂ was added to CO2, which indicated that variations in the initial electron content affected the inception process of streamer discharge.

Optical Automatic Contour Tracing (O-ACT) - A novel optical image-guided contour tracing method for electron beam shaping.

Electron therapy, vital for treating skin lesions and superficial tumors, demands precise electron cutouts to ensure accurate dose delivery. Traditional manual tracing methods introduce uncertainties and inefficiencies, necessitating innovative solutions for custom block creation. To introduce and validate the Optical Automatic Contour Tracing (O-ACT) method, enhancing electron cutout generation's accuracy and efficiency through optical imaging and software automation. Utilizing a 3D-printed holder, a centrally-mounted charge-coupled device (CCD) camera on the electron applicator secured two distinct perspective images of the skin's contour at varying heights. Through image binarization and skeletonization, we identified the clinical target contour's region-of-interests (ROIs) in each setup image. Employing distances from each ROI's center, assessed at 5-degree intervals from both images, we reconstructed the target contour on the skin. The magnification factor, set at a 95cm source-to-point distance, determined the final cutout shape. We crafted an in-house software in MATLAB for camera calibration and image processing and juxtaposed our results against the standard clinical cutout from the treatment planning system (TPS) using a correlation coefficient based on masked binary images' mutual information. Additionally, we performed dosimetric evaluations using abstract shapes to compare O-ACT with other methods. Our methodology yielded cutout shapes exhibiting remarkable alignment with the TPS clinical cutout. O-ACT demonstrated superior precision in generating cutout shapes that closely align with the contours in TPS, improving upon other methods in terms of adaptability to patient body shapes and contour accuracy. Dosimetric evaluations showed minimal differences between methods, with O-ACT providing slightly more consistent results. Dose profile analyses in penumbra regions indicated O-ACT's improved accuracy compared to conventional methods. Pushing the boundaries of traditional practices, our O-ACT offers a more accurate, efficient, and reproducible method for custom electron cutout creation from clinical setup images. This innovation promises not only to streamline clinical workflow but also to potentially uplift clinical outcomes in radiation oncology by providing more accurate patient-specific treatment accessary.

Improving charge transfer efficiency in CCDs: A SILVACO-based numerical study

In this study, we investigate the charge transfer efficiency (CTE) of a radiation-damaged charge-coupled device (CCD) subjected to proton radiation levels typical of space-borne experiments, nuclear imaging, and particle detection. The primary factor affecting CTE in such damaged CCDs is the trapping of charge carriers by bulk states. Our analysis examines CTE as a function of temperature, and radiation-created traps (trap levels). We employed a two-dimensional numerical model using the SILVACO semiconductor simulation software to simulate the dynamic transfer process in a buried-channel CCD (BCCD) with a three-phase clock pulse driver. After setting the appropriate physical models and the suggested deep traps levels in the channel region. The simulations demonstrate that the CTE shows a nonlinear dependence on temperature, with a charge transfer inefficiency (CTI) peaking at 7x10-6 at 135 K and reaching a minimum value of 2x10-6 around 200 K. These simulated results closely match the experimental data found in the literature, providing a comprehensive understanding of the impact of radiation-induced traps on the dynamic charge transfer processes in CCDs.

Inverse Design of Aberration-Corrected Hybrid Metalenses for Large Field of View Thermal Imaging Across the Entire Longwave Infrared Atmospheric Window.

Long wave infrared (LWIR) cameras play a pivotal role across diverse applications due to their distinctive features. The growing demand for high-performance thermal imaging optics, characterized by a broad working bandwidth, large field of view (FOV), aberration-free design, lightweight construction, compactness, and cost-effectiveness, poses significant challenges for LWIR lens design. Here, we propose an inverse design method for LWIR hybrid metalenses, specifically aiming to achieve aberration-corrected thermal imaging with both a large FOV and a broad working bandwidth. Our approach involves optimizing phase profiles of metalens' unit cells guided by a loss function that compares the hybrid lens design to diffraction-limited results for various incident angles and wavelengths. As a result, we demonstrate an aberration-corrected thermal camera with a 30° FOV and an achromatic working bandwidth spanning the entire LWIR atmospheric window (8 to 14 μm). Significantly, the total optical path length, the entrance pupil to the sensor plane of the charge-coupled device (CCD), is a mere 13.6 mm. Our work merits advantages in the FOV, working bandwidth, and compactness, which surpass state-of-the-art LWIR hybrid metalens designs and find numerous imaging and sensing applications.

Rapid and specific screening of monoclonal antibodies in hybridoma supernatants by an enzyme-based dipstick immunoassay

Hybridoma technology remains a cornerstone of monoclonal antibody (mAb) discovery. Classical screening practices such as ELISA, western blot, and dot blot require laborious, time-consuming procedures, rendering them inefficient in time-restricted decision-making. Additionally, due to these assays’ practical and technical limitations, specificity testing of the mAbs is usually omitted during the primary screening of hybridoma libraries. Herein, we present a rapid, dipstick immunoassay (DIA) designed for mAbs screening in cell culture supernatant. The integrated proprietary setup is based on antibody capture and comprises accessible materials such as conjugate pad, nitrocellulose membrane, and absorbent pad. The critical element of this technology is the design of the assay. During the assay run, dipsticks are inserted into supernatant-containing microtiter wells, initiating capillary flow of mAbs towards the conjugate pad where a pre-dried HRP-labeled anti-host species antibody is embedded. This interaction forms an immunocomplex, which migrates to the nitrocellulose membrane and binds to the pre-immobilized target antigen while simultaneously encountering immobilized putative cross-reacting proteins in a multiplex-line fashion. Upon addition of HRP-oxidizable substrate, signal acquisition is performed using a simple camera (colorimetry) or a CCD sensor (chemiluminescence). The system was quantitative up to 2500 ng mL−1 and showed a minimum detectable concentration of 0.61 ng mL−1. Compared to the gold-standard ELISA, the sensitivity was 8-fold higher, while the dynamic range was similar. Critically, the assay allows for the concurrent assessment of antibody specificity in one run. This immunoassay’s unique configuration, simplicity, and rapidity can facilitate antibody discovery.

Modeling the Wavelength Dependence of Pixel Response Nonuniformity of a CCD Sensor

Precision measurements in astronomy require stringent control of systematics such as those arising from imperfect correction of sensor effects. In this work, we develop a parametric method to model the wavelength dependence of pixel response nonuniformity (PRNU) for a laser-annealed backside-illuminated charge-coupled device. The model accurately reproduces the PRNU patterns of flat-field images taken at nine wavelengths from 290 to 950 nm, leaving the rms residuals no more than 0.2% in most cases. By removing the large-scale nonuniformity in the flat fields, the rms residuals are further reduced. This model fitting approach gives more accurate predictions of the PRNU than cubic-spline interpolation does with fewer free parameters. It can be applied to make PRNU corrections for individual objects according to their spectral energy distribution to reduce the photometry errors caused by the wavelength-dependent PRNU, if sub-percent level precision is required.

Cooling Trapped Ions with Phonon Rapid Adiabatic Passage

In recent demonstrations of the quantum charge-coupled device computer architecture, circuit times are dominated by cooling. Some motional modes of multi-ion crystals take orders of magnitude longer to cool than others because of low coolant ion participation. Here we demonstrate a new technique, that solves this issue by coherently exchanging the thermal populations of selected modes on timescales short compared to direct cooling. Using this method, which we call “phonon rapid adiabatic passage,” we can achieve subquanta temperatures from initial states with occupations as high as n¯∼200 quanta. Analogous to adiabatic rapid passage, we quasistatically couple these slow-cooling modes with fast-cooling modes using dc electric fields. When the crystal is then adiabatically ramped through the resultant avoided crossing, nearly complete phonon population exchange results. We demonstrate this on two-ion crystals, and show the indirect ground-state cooling of all radial modes—achieving an order of magnitude speedup compared to direct cooling. We also show the technique’s insensitivity to trap potential and control field fluctuations, and find that it still achieves subquanta temperatures starting as high as n¯∼200. Published by the American Physical Society 2024

Design and fabrication of a dual laser Raman spectrometer with a single one-dimensional CCD detector

The combination of two spectrometers in dual-laser Raman devices without the need for moving parts represents a significant advancement. This study focuses on design and fabrication of a dual spectrometer with no moving components, allowing data to be gathered using a single detector. This instrument consists of two Czerny–Turner optical arrangements which is symmetrically merged. Dual spectrometer single detector has two light inputs, each of them, concentrating the light separately on a one linear charge-coupled device detector through two independent optical paths. In this innovative spectrometer design, no optical moving parts are used, and therefore, the wavelength displacement error in repeating the spectroscopic experiment is zero. The independent nature of the optical paths enables the optimization of each spectrometer arrangement without affecting the other. The final spectrometer has a spectral resolution of 4.6 and 6.11 cm− 1 for Full Width at Half Maximum across the wavelength ranges of 532 to 708 nm and 784.65 to 1100 nm, respectively. Switching between the two different acquisition setups can be done seamlessly and quickly, with the ability to record approximately 2000 spectra per second. Standard neon and mercury-argon lamps’ atomic radiation spectra, along with Raman scattering data from a cyclohexane standard sample, were successfully recorded using laser wavelengths of 532 nm and 784.65 nm.

Multisource data fusion for defect detection in composite additive manufacturing using explainable deep neural network

Composite additive manufacturing has the potential to replace traditional composite manufacturing for aerospace applications. Additive manufacturing provides greater adaptability to complex designs, reduce material waste, and streamline the production process. However, in comparison to conventional composite manufacturing methods, additive manufacturing is inherently more susceptible to processing anomalies and defects, primarily due to the novelty of the process and the absence of applied pressure. To effectively capitalize on the benefits of additive manufacturing, a quality and reliability assurance system is critical. In this study, we have generated multisource data to analyze the inner layer thermography and surface quality, employing a multi-camera system including thermal and charge-coupled device cameras. This multisource data is utilized in an explainable zero bias deep neural network framework to detect manufacturing defects. This deep learning algorithm introduces a new zero bias layer following the regular dense layer. After being trained on normal (defect-free) samples of each data stream, the trained model is transformed into an anomaly detector by extracting low dimension features from the zero-bias layer. This allowed identification various anomalies without having to train the model on any defective inputs. As a result, the model's accuracy to detect multiple types of anomalies is higher with multisource data compared to models based on single data source. Anomaly detection accuracy was 99.72% when using data from multiple sources, 98.28% when using only CCD images, and 95% when using only thermal camera data.

Charge-coupled device readout by digital-correlated double sampling

Charge-coupled devices (CCDs) play crucial roles in astronomy owing to their widespread use in the optical band, offering high sensibility, low noise, high dynamic range, and high spatial resolution. Recent advancements in CCDs have focused on improving the sub-electron noise levels for particle detection and enhancing readout speeds through simulation studies. The main objective of this study is to replace the analog processing of CCD signals using the digital-correlated double sampling (DCDS) technique. DCDS allows post-acquisition noise correction through intermittent sampling of an internal reference voltage to provide compact and flexible performance. In this study, DCDS was evaluated using two digital processing systems, namely, a 2.5 mega-samples per second (MSPS) 24-bit analog-to-digital converter (ADC) board and a 250 MSPS 16-bit ADC field-programmable-gate-array( FPGA)-based buffer memory board. The readout noise value at 74 kpix/s (7.1 e) was a significant improvement over that obtained with analog processing (9.7 e). The DCDS implementation demonstrates optimal signal-to-noise ratio for a wide range of readout speeds. Parameters such as the sample positions per pixel, number of samples, and number of pixels were identified to be essential in achieving an accurate gain value. Finally, hardware implementation of the DCDS IP core algorithm on a Xilinx Zynq-7000 AP system-on-a-chip (SoC) showed a significant improvement in power dissipation (7.1 W) compared to the analog Monsoon correlated double sample (CDS) circuit (13.6 W). The DCDS IP core implementation also showed a background noise reduction of up to 34% compared to DCDS offline readout processing using a Python algorithm.

Enhancing Long-Term Robustness of Inter-Space Laser Links in Space Gravitational Wave Detection: An Adaptive Weight Optimization Method for Multi-Attitude Sensors Data Fusion

The stable and high-precision acquisition of attitude data is crucial for sustaining the long-term robustness of laser links to detect gravitational waves in space. We introduce an effective method that utilizes an adaptive weight optimization approach for the fusion of attitude data obtained from charge-coupled device (CCD) spot-positioning-based attitude measurements, differential power sensing (DPS), and differential wavefront sensing (DWS). This approach aims to obtain more robust and lower-noise-level attitude data. A system is designed based on the Michelson interferometer for link simulations; validation experiments are also conducted. The experimental results demonstrate that the fused data exhibit higher robustness. Even in the case of a single sensor failure, valid attitude data can still be obtained. Additionally, the fused data have lower noise levels, with root mean square errors of 9.5%, 37.4%, and 93.4% for the single CCD, DPS, and DWS noise errors, respectively.

Ultra-compact on-chip camera based on optoelectronic compound eyes with nonuniform ommatidia

Abstract Compound eyes (CEs) that feature ultra-compact structures and extraordinary versatility have revealed great potential for cutting-edge applications. However, the optoelectronic integration of CEs with available photodetectors is still challenging because the planar charge-coupled device (CCD)/complementary metal oxide semiconductor (CMOS) detector cannot match the spatially distributed images formed by CE ommatidia. To reach this end, we report here the optoelectronic integration of CEs by manufacturing 3D nonuniform ommatidia for developing an ultra-compact on-chip camera. As a proof-of-concept, we fabricated microscale CEs with uniform and nonuniform ommatidia through femtosecond laser two-photon photopolymerization, and compared their focusing/imaging performance both theoretically and experimentally. By engineering the surface profiles of the ommatidia at different positions of the CE, the images formed by all the ommatidia can be tuned on a plane. In this way, the nonuniform CE can be directly integrated with a commercial CMOS photodetector, forming an ultra-compact CE camera. Additionally, we further combine the CE camera with a microfluidic chip, which can further serve as an on-chip microscopic monitoring system. We anticipate that such an ultra-compact CE camera may find broad applications in microfluidics, robotics, and micro-optics.

Light curve modeling of the eclipsing binary systems V0876 Lyr, V3660 Oph, and V0988 Mon

Abstract Photometric study and light curve modeling for the systems V0876 Lyr, V3660 Oph, and V0988 Mon were carried out by means of their first charge-coupled device observations and the Wilson–Devinney code based on model atmospheres by Kurucz (1993. In: Milone, E. (Ed.), Light curve modeling of eclipsing binary stars. New York: Springer-Verlag. p. 93). The accepted models reveal physical parameters that show that all the primary components of the studied systems are more massive and hotter than the secondary ones. The systems V0876 Lyr and V0988 Mon were classified as over contact, with mass ratios of 0.8940 and 0.3904, respectively, while the system V366Oph was classified as detached, with a mass ratio of 0.1181. The evolutionary state of the system components was investigated, and their spectral types were adopted. Both components of the system V0876 Lyr and secondary components of the systems V3660 Oph and V0988 Mon show lower radii and luminosities than expected for Zero Age Main Sequence (ZAMS). Secondary components of the system, V3660 Oph and V0988 Mon, deviated from ZAMS and the Terminal-age Main Sequence (TAMS) with a higher radius and luminosity than expected for ZAMS and TAMS.