Linear Charge-coupled Device Research Articles

General Model of Photon-Pair Detection with an Image Sensor.

We develop an analytic model that relates intensity correlation measurements performed by an image sensor to the properties of photon pairs illuminating it. Experiments using an effective single-photon counting camera, a linear electron-multiplying charge-coupled device camera, and a standard CCD camera confirm the model. The results open the field of quantum optical sensing using conventional detectors.

A Gradient Grating Period Guided-Mode Resonance Spectrometer

This paper reports a compact spectrometer based on a guided-mode resonance (GMR) filter mounted on a linear charge-coupled device (CCD). The GMR is specially designed to exhibit gradient grating periods (GPPs) laterally to ensure that the GMR functions as a linear-variable bandstop filter. Each period corresponds to a resonant wavelength such that this wavelength is reflected back at its corresponding resonant period and transmitted to all other periods. Consequently, when a resonant wavelength is incident on the GGP-GMR attached to a linear CCD, the CCD pixel underneath its resonant period receives the minimum intensity, and the other pixels receive higher intensities. In terms of the wavelength range of interest, by scanning a single wavelength at a time, a transmission efficiency matrix that contains the transmission efficiency of each wavelength at each pixel can be established. An unknown incident spectrum can be reconstructed using the established transmission efficiency matrix and the intensity measured using the CCD. In this study, a GGP-GMR spectrometer less than 3 mm long that can achieve a wavelength detection range of 200 nm was demonstrated to reconstruct various incident spectra, including a single wavelength of light with a resolution of 0.5 nm, a single wavelength of light with varying intensity levels, and dual incident light sources.

Research on Geometric Calibration of Spaceborne Linear Array Whiskbroom Camera.

The geometric calibration of a spaceborne thermal-infrared camera with a high spatial resolution and wide coverage can set benchmarks for providing an accurate geographical coordinate for the retrieval of land surface temperature. The practice of using linear array whiskbroom Charge-Coupled Device (CCD) arrays to image the Earth can help get thermal-infrared images of a large breadth with high spatial resolutions. Focusing on the whiskbroom characteristics of equal time intervals and unequal angles, the present study proposes a spaceborne linear-array-scanning imaging geometric model, whilst calibrating temporal system parameters and whiskbroom angle parameters. With the help of the YG-14—China’s first satellite equipped with thermal-infrared cameras of high spatial resolution—China’s Anyang Imaging and Taiyuan Imaging are used to conduct an experiment of geometric calibration and a verification test, respectively. Results have shown that the plane positioning accuracy without ground control points (GCPs) is better than 30 pixels and the plane positioning accuracy with GCPs is better than 1 pixel.

A capillary blood flow velocity detection system based on linear array charge-coupled devices

In order to detect the flow characteristics of blood samples in the capillary, this paper introduces a blood flow velocity measurement system based on field-programmable gate array (FPGA), linear charge-coupled devices (CCD) and personal computer (PC) software structure. Based on the analysis of the TCD1703C and AD9826 device data sheets, Verilog HDL hardware description language was used to design and simulate the driver. Image signal acquisition and the extraction of the real-time edge information of the blood sample were carried out synchronously in the FPGA. Then a series of discrete displacement were performed in a differential operation to scan each of the blood samples displacement, so that the sample flow rate could be obtained. Finally, the feasibility of the blood flow velocity detection system was verified by simulation and debugging. After drawing the flow velocity curve and analyzing the velocity characteristics, the significance of measuring blood flow velocity is analyzed. The results show that the measurement of the system is less time-consuming and less complex than other flow rate monitoring schemes.

High-throughput imaging of zebrafish embryos using a linear-CCD-based flow imaging system.

High-throughput imaging and screening is essential for biomedical research and drug discovery using miniature model organisms such as zebrafish. This study introduces a high-speed imaging system which illuminates zebrafish embryos flowing through a capillary tube with a sheet of light and captures them using a linear charge-coupled device (CCD). This system can image dozens of zebrafish embryos per second. An image algorithm was developed to recognize each embryo and to perform automatic analysis. We distinguished dead and living embryos according to the gray level distribution and conducted statistics of morphological characteristics of embryos at different growing stages.

Detection and Estimation of Along-Track Attitude Jitter From Ziyuan-3 Three-Line-Array Images Based on Back-Projection Residuals

High-resolution satellite images (HRSIs) obtained from linear array charge-coupled device sensors always suffer from geometric instability in the presence of attitude jitter. Therefore, detection and compensation of spacecraft attitude jitter in both the cross-track and along-track directions are crucial to improve the geometric accuracy of HRSIs. A number of reports have been made on the detection and estimation of cross-track attitude jitter. However, the detection of the attitude jitter in the along-track direction is more complicated due to the impact of topographic change. This paper presents a novel approach to achieve accurate estimation of the along-track attitude jitter by eliminating the influence of topographic information based on the back-projection residuals of three-line-array (TLA) images. The principle of detection and estimation of along-track attitude jitter is described, and the proposed approach consists of three main components as follows: 1) dense image matching of the TLA images using a comprehensive matching strategy; 2) detection of the back-projection residuals in the line direction caused by attitude jitter; and 3) estimation of the along-track attitude jitter from the back-projection residuals using a genetic algorithm. Experiments were conducted using China’s Ziyuan-3 (ZY-3) TLA images, and the experimental results reveal that the frequency of the attitude jitter in the along-track direction ranges between 0.6 and 0.7 Hz, which is consistent with the frequency in the cross-track direction observed in our previous study. In addition, a comparison of the results of the proposed approach with those from direct attitude observations shows good consistency, with as little as 0.1-pixel disparity, which demonstrates the feasibility and reliability of the proposed approach. Furthermore, the geometric accuracy is further improved from a pixel level to a subpixel level and the periodic trend is removed with the compensation of the estimated attitude jitter in addition to the conventional affine compensation, which validates the potential of the proposed approach for geometric accuracy improvement with ZY-3 TLA images.

Design of the CCD-TCD2964BFG Drive and Sampling Based on FPGA

This technology is mainly focused on the charge coupled device (CCD)TCD2964BFG as image sensor and using AD9826 as sampling chip, which introduces a design of driving and sampling circuit based on the FPGA of Altera Corporation. It discusses the design of driving and control timing by using FPGA chip EP4CE30F23C7N technology. Then it describes the design of the CCD driver board and the CCD mounting board in detail. This is a pivotal design to high-precision measurement, color image scanning and so on. Its highest accuracy can be reached 4800DPI with high resolution when it works and its output signal can be more reliable, more stable by being processed by AD9826, so it is very important for high-precision measurement, color image scanning ,etc. While making it into sub-circuit board physical model by using integrated circuit form, meanwhile, it’s very convenient to connect with a variety of FPGA core boards and it can be applied on various occasions by outgoing interface signals. The design is known for its flexibility, high integration, easy to update, convenient to apply and so on. The observed results indicate that the design of driving timing and circuit can meet the normal demands for the color linear CCD.

Versatile CCD‐based spectrometer with field programmable gate array controller core

The design and implementation of a novel room temperature charge-coupled device (CCD) spectrometer is presented. The timing generator and data acquisition circuits driving a 16,020 photodiode linear tricolour CCD detector capable of 24 dots per millimetre are described. Linear detection of ultraviolet, infrared and visible wavelengths over total wavelength range of 300 to 1000 nm of total wavelength range is possible by using three-colour array multiplexing. The field programmable gate array logic processing realises a low-cost, high-speed digital spectrometer with USB interface. A finite state automaton is used to generate low-skew, high-speed complex clocks to drive the system. The output of the instrument is 8 bit array intensity versus wavelength array acquired using semi-flash, 20 Mb/s analogue-to-digital converter, realising a 1.23 Gb/s per colour readout rate on the CCD. The resulting spectrometer is capable of USB 2.0 communication with high-level processing programmes.

Autoinducer-2 analogs and electric fields - an antibiotic-free bacterial biofilm combination treatment

Bacterial biofilms are a common cause of chronic medical implant infections. Treatment and eradication of biofilms by conventional antibiotic therapy has major drawbacks including toxicity and side effects associated with high-dosage antibiotics. Additionally, administration of high doses of antibiotics may facilitate the emergence of antibiotic resistant bacteria. Thus, there is an urgent need for the development of treatments that are not based on conventional antibiotic therapies. Presented herein is a novel bacterial biofilm combination treatment independent of traditional antibiotics, by using low electric fields in combination with small molecule inhibitors of bacterial quorum sensing - autoinducer-2 analogs. We investigate the effect of this treatment on mature Escherichia coli biofilms by application of an alternating and offset electric potential in combination with the small molecule inhibitor for 24h using both macro and micro-scale devices. Crystal violet staining of the macro-scale biofilms shows a 46% decrease in biomass compared to the untreated control. We demonstrate enhanced treatment efficacy of the combination therapy using a high-throughput polydimethylsiloxane-based microfluidic biofilm analysis platform. This microfluidic flow cell is designed to reduce the growth variance of in vitro biofilms while providing an integrated control, and thus allows for a more reliable comparison and evaluation of new biofilm treatments on a single device. We utilize linear array charge-coupled devices to perform real-time tracking of biomass by monitoring changes in optical density. End-point confocal microscopy measurements of biofilms treated with the autoinducer analog and electric fields in the microfluidic device show a 78% decrease in average biofilm thickness in comparison to the negative controls and demonstrate good correlation with real-time optical density measurements. Additionally, the combination treatment showed 76% better treatment efficacy compared to conventional antibiotic therapy. Taken together these results suggest that the antibiotic-free combination treatment described here may provide an effective alternative to traditional antibiotic therapies against bacterial biofilm infections. Use of this combination treatment in the medical and environmental fields would alleviate side effects associated with high-dosage antibiotic therapies, and reduce the rise of antibiotic-resistant bacteria.

Evaluation of the Degradation on a COTS Linear CCD Induced by Total Ionizing Dose Radiation Damage

The evaluation of the degradation on a COTS linear Charge Coupled Device (CCD) induced by total ionizing dose (TID) radiation damage was presented. The radiation experiments were carried out at a60Coγ-ray source. The parameters of DALSA’s linear CCD were measured at the CCD test systems as the EMVA1288 standard before and after the radiation. The dark current, dark signal nonuniformity (DSNU), photo response nonuniformity (PRNU), saturation output, full-well capacity (FWC), quantum efficiency (QE), and responsivity versus the TID were analyzed. The behavior of the tested CCD had shown a remarkable degradation after radiation. The degradation mechanisms of the CCD induced by TID damage were also discussed.

Effect of correction methods of radiochromic EBT2 films on the accuracy of IMRT QA

Radiochromic films are dosimeters with more favorable characteristics than other two-dimensional (2D) radiation detectors. Transmission film scanners using a linear charge-coupled device (CCD) array have a drawback of variation in response along the detector array, which may result in a nonuniform transmission of signal over the scanned image. This study uses 2D gamma index analysis to compare two methods for correcting the nonuniform response of EBT2: the first method was based on the new red:blue method proposed by the manufacturer (to compensate for small nonuniformities in the film coating) and the second method, proposed by Menegotti et al. (2008), was based on dose-dependent matrix correction factors. The gamma index analysis shows that both the methods are comparably accurate for all the criteria values used for evaluation (1mm/1%, 2mm/2%, 3mm/3%). Centers around the world use both the methods to correct EBT2 local heterogeneities, but it is important to note that the former method has several advantages such as less time consumption and easy implementation.

Low-resolution continuum source simultaneous multi-element electrothermal atomic absorption spectrometry: steps into practice

The theory and practical problems of continuum source simultaneous multi-element electrothermal atomic absorption spectrometry (SMET AAS) are discussed by the example of direct analysis of underground water. The experimental methodology is based on pulse vaporization of the sample in a fast heated graphite tube and measurement of transient absorption of continuum spectrum radiation from D2 and Xe lamps within 200–400nm wavelengths range with a low resolution spectral instrument and linear charge-coupled device. The setup permits the acquisition of 200 spectra during 1s atomization pulse. Respective data matrix absorbance vs wavelength/time is employed for the quantification of elements in the sample. The calculation algorithm developed includes broad band and continuum background correction, linearization of function absorbance vs. concentration of atomic vapor and integration of thus modified absorbance at the resonance lines of the elements to be determined. Practical application shows that the method can be employed for the direct simultaneous determination of about 20 elements above microgram per liter level within 3–5 orders of the magnitude concentration range. The investigated sources of measurement errors are mainly associated with the atomization and vapor transportation problems, which are aggravated for the simultaneous release of major and minor sample constituents. Respective corrections concerning the selection of analytical lines, optimal sampling volume, matrix modification and cleaning of the atomizer have been introduced in the SMET AAS analytical technology. Under the optimized experimental conditions the calibration curves in Log-Log coordinates for all the investigated analytes in the single or multi-element reference solutions are approximated by the first order equations. The use of these equations as permanent characteristics of the setup enables instant quantification of Al, Ca, Co, Cr, Cu, Fe, Mg, Mn and Ni in the underground water samples with an accuracy of 30%.

Study on the Time-grating Displacement Sensor of the Static Light Field Type Based on Linear Charge-coupled Device

According to the design ideology of time-grating sensor, continuing with the research foundation of the magnetic field type and electronic field type in the past, a time-grating sensor of light field type is put forward and analyzed. In addition, the principle and implementation plans are proposed. On the basis of measurement principle of time-grating, exploratory presented a method of uniform scanning by using photoelectric detector of timing driven, to convert the displacement detection of the object into measured time difference. To verify the validity of the scheme, a charge-coupled device(CCD) time-grating prototype is designed by a circular array which is constituted by multiple linear CCD of the same type. After multiplied the time difference variation of the output electric signal on the adjacent CCD and the uniform scanning speed value, through proper transformation, size and direction of the relative shaft angular displacement would be got. By measuring compare with circular grating which measurement accuracy reach within ±1″, measuring errors with a developed prototype are controlled within ±6° in the range of entire circumference. A reliable basis of theoretic and practical is provided for the further study on the time-grating of light field type.

Research of the Rice Image Segmentation Based on Color Linear Array CCD

Using color linear array CCD (Charge Coupled Device) to collect the information of image has an important meaning in the research of the machine vision processing. It now becomes the focus of study on CCD image acquisition using FPGA (Field Programmable Gate Array) to implement color linear array CCD-driven design. The image acquisition and processing of the rice color sorter as the research background in this paper, by using FPGA to achieve the color linear array CCD driven control, as well as simulated with Quartus II 8.0. In order to be able to extract the color linear array CCD output useful information of the color images, through study the RGB model and the HSI (Huge, Saturation, Intensity) model of color space model, the HSI space mode is selected as the color image processing space model, and design the suitable algorithm-FCM (Fuzzy CMeans) clustering algorithm in HSI space for color image segmentation, through a fuzzy Toolbox in MATLAB to accomplish the FCM algorithm, at the same time, through the simulation realized the FCM algorithm. The simulation shows that the algorithm can segment the image useful information well.

Design of High-Resolution FPD System Based on Doglegged Sampling

For the shortcomings of methods used to improve the image spatial resolution of current linear charge coupled device (CCD) FPD System, a new sampling method is proposed, and a high-resolution FPD System is designed. Two same linear CCD cameras arc fixed with specific spatial arrangement, namely both camera 1 and camera 2's CCD scan the object with a tilt angle B, and image correction and pixel interpolation arc also used for getting high-resolution image. The experimental results show that, compared with the regular scanning mode equipped with a signal camera and =0¡ã, in our method cameras with slant angle =60¡ãenables the image spatial resolution doubled, and keeps the field of view unchanging. It is easy to realize the designed system in engineering, very economical and convenient to maintain it, and only using the existing imaging device to obtain higher-resolution images.

Optical Layout and Alignment Methods for Visible Tomography and Emission Spectroscopy Diagnostics in SPIDER

SPIDER, a prototype negative ion source with low voltage extraction for the ITER neutral beam injector will be equipped with a set of diagnostics to qualify and optimize the neutral beam for ITER. In particular, the visible tomography diagnostic will estimate the uniformity of the beam using a set of linear charge-coupled device cameras, while emission spectroscopy will measure the spatial variation of plasma parameters in the RF plasma source and evaluate the divergence of the extracted beam, analyzing the spectrum collected over multiple lines of sight (LOS). This paper presents the optical layout of the LOS and detection heads of tomography and spectroscopy and the required accuracy in their alignment, proposing also alignment criteria.

A novel automatic measurement method of laser beam divergence angle based on two linear array charge coupled devices

We propose a scanning imaging measurement method using two linear array charge coupled devices (CCD) to evaluate the transmission performance of the linear laser beam of 90° × 2°. The two linear array CCDs are placed at two positions in the far field separated by a definite angle. The beam divergence angles in the view direction are measured by linear fitting because the beam width conforms to the linear relationship in the far field. This method has the ability for real-time testing and is appropriate for the complicated beam shapes with a wide measurement range.

Real-time Alignment of Infrared CCD Based on the Assembly Precision

Aiming at the overly dependent on the splicing apparatus precision and low efficiency of splicing of infrared linear charge-coupled device(CCD). A real-time alignment of infrared CCD based on the assembly precision is proposed. The spatial position of the assembled chip is got in real time. The overall assembly precision model of CCD will be constructed according to the requirements of the CCD spatial position. then the chip coordinate information which will be fitted is determine through the ant colony algorithm, guide the actual assembly and adjust tooling adjustments. It is effectively to achieve real-time monitoring and rapid alignment of the splicing process. Through the experiments of the prototype system alignment, the time of CCD alignment can be controlled in 3 days, have remarkable increase efficiency compared with traditional methods, while lap error is no more than 6 μm, straightness is no more than 8 μm, parallelism is no more than 10 μm, meeting the project requirements.

Defective kernel detection using a linear colour CCD

This study was aimed at detecting defective wheat (Triticum durum Desf) with a machine vision system of linear colour charge-coupled device. One thousand one hundred and sixty-nine images were captured for sound kernels, 710 for black germ kernels and 627 for broken kernels. A software package was developed to extract various morphological, colour and texture features from the images captured. Then the experimental data were subjected to multivariate analysis. Principal component analysis was employed to differentiate samples from different categories. Partial least square discriminant analysis and venetian blinds cross-validation were used to develop classification models. The best detection accuracies of samples were 92·7, 88·0 and 89·6% for black germ kernels, broken kernels and sound kernels. The results have proved that it is feasible and effective to employ partial least square discriminant analysis for feature selection and defective kernel detection.

Measurement of UV from a Microplasma by a Microfabricated Amorphous Selenium Detector

We spectrally demonstrate for the first time that an amorphous selenium metal-semiconductor-metal detector can be used for the measurement of ultraviolet photons (200-400 nm) generated from a portable battery-operated microplasma that is used as a light source. An advantage of this low-cost detector is that the device structure allows photons to strike the light-sensitive layer directly rather than through electrodes or blocking layers. Another advantage is that despite operation at high electric fields of up to 43 V/μm, the dark current of the detector at room temperature is 3 pA/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Therefore, detector cooling is not required, and this facilitates portability for measurements on-site (i.e., in the field and away from a laboratory). Spectral response was monitored using a scanning monochromator, and it was compared with that obtained by a portable spectrometer fitted with a linear charge-coupled device detector. To demonstrate detector responsivity, emission signals with an appreciable signal-to-noise ratio were obtained by introducing nanogram amounts of the sample into the microplasma.