Charge-coupled Device Image Sensor Research Articles

Visualization of microvessels by angiography using inverse-Compton scattering X-rays in animal models

The fundamental performance of microangiography has been evaluated using the S-band linac-based inverse-Compton scattering X-ray (iCSX) method to determine how many photons would be required to apply iCSX to human microangiography. ICSX is characterized by its quasi-monochromatic nature and small focus size which are fundamental requirements for microangiography. However, the current iCSX source does not have sufficient flux for microangiography in clinical settings. It was determined whether S-band compact linac-based iCSX can visualize small vessels of excised animal organs, and the amount of X-ray photons required for real time microangiography in clinical settings was estimated. The iCSX coupled with a high-gain avalanche rushing amorphous photoconductor camera could visualize a resolution chart with only a single iCSX pulse of ∼3 ps duration; the resolution was estimated to be ∼500 µm. The iCSX coupled with an X-ray cooled charge-coupled device image sensor camera visualized seventh-order vascular branches (80 µm in diameter) of a rabbit ear by accumulating the images for 5 and 30 min, corresponding to irradiation of 3000 and 18000 iCSX pulses, respectively. The S-band linac-based iCSX visualized microvessels by accumulating the images. An iCSX source with a photon number of 3.6 × 10(3)-5.4 × 10(4) times greater than that used in this study may enable visualizing microvessels of human fingertips even in clinical settings.

Three-dimensional step–height measurement using sinusoidal wavelength scanning interferometer with four-step phase-shift method

A sinusoidal wavelength scanning interferometer with the four-step phase-shift method is demonstrated for a three-dimensional profile measurement. The interference phase-shift signal generated by the sinusoidal wavelength scanning contains information about optical path difference covering a nm-μm scale structure. The interference phase-shift signal was obtained by the four-step phase-shifting method. The sinusoidal wavelength shifting with a frequency of approximately 180 Hz and tunable range of 5.7 nm was performed by the Littman–Metcalf external resonator-type tunable laser with a center of 772.1 nm. The full-field surface profile measurement was conducted by a charge coupled device image sensor with an accuracy on a nm scale. The surface profiles of gauge blocks with a step height up to about 10 μm were successfully measured with a surface profile irregularity of 3.8×10−2 μm. The deviations of two measured surfaces of upper and lower steps were estimated to be 1.6×10−2 μm and 3.1×10−2 μm, respectively.

Design of a hardware/software FPGA-based driver system for a large area high resolution CCD image sensor

A hardware/software field programmable gate array (FPGA)-based driver system was proposed and demonstrated for the KAF-39000 large area high resolution charge coupled device (CCD). The requirements of the KAF-39000 driver system were analyzed. The structure of “microprocessor with application specific integrated circuit (ASIC) chips” was implemented to design the driver system. The system test results showed that dual channels of imaging analog data were obtained with a frame rate of 0.87 frame/s. The frequencies of horizontal timing and vertical timing were 22.9 MHz and 28.7 kHz, respectively, which almost reached the theoretical value of 24 MHz and 30 kHz, respectively.

CCD image sensor induced error in PIV applications

The readout procedure of charge-coupled device (CCD) cameras is known to generate some image degradation in different scientific imaging fields, especially in astrophysics. In the particular field of particle image velocimetry (PIV), widely extended in the scientific community, the readout procedure of the interline CCD sensor induces a bias in the registered position of particle images. This work proposes simple procedures to predict the magnitude of the associated measurement error. Generally, there are differences in the position bias for the different images of a certain particle at each PIV frame. This leads to a substantial bias error in the PIV velocity measurement (∼0.1 pixels). This is the order of magnitude that other typical PIV errors such as peak-locking may reach. Based on modern CCD technology and architecture, this work offers a description of the readout phenomenon and proposes a modeling for the CCD readout bias error magnitude. This bias, in turn, generates a velocity measurement bias error when there is an illumination difference between two successive PIV exposures. The model predictions match the experiments performed with two 12-bit-depth interline CCD cameras (MegaPlus ES 4.0/E incorporating the Kodak KAI-4000M CCD sensor with 4 megapixels). For different cameras, only two constant values are needed to fit the proposed calibration model and predict the error from the readout procedure. Tests by different researchers using different cameras would allow verification of the model, that can be used to optimize acquisition setups. Simple procedures to obtain these two calibration values are also described.

Adaptive Front Lighting System Using CCD

This paper analyzed features of headlamps of vehicle when turning the corner. When vehicle is driven on curved road headlamps turns as per vehicle body hence it has limited illumination. The adaptive front lightning system (AFS) improves visibility during night time driving. This project developed a new type of AFS (adaptive front-lighting system) based on CCD (charge-coupled device) which was better than traditional AFS. The main aim is to find curvature of road ahead in advance before turning the corner so as to adjust turning angle and steering accordingly. This new AFS used CCD image sensor to detect information about the corner and then sent curvature radius to control unit in advance. Meanwhile, accurate rotation angle of headlamps would calculated by control unit through curvature radius, and send it to servomotor to adjust headlamps to get the lighting beam which was suitable for the corner. By using this way, it could avoid blind spot caused by the fixed lighting area when coming into the corner, and improve driving safety.

Exquisite Design of a CCD Analog Front End Module

One of the key technologies for high-resolution camera is the analog front end (AFE) design, which is between the lens and image system process (ISP). The 2 major evaluations of AFE are to evaluate the noise and the ratio between the RGB pixels. Hence, based on the charge coupled device (CCD) image sensor, we present our proposed AFE design to evaluate the CCD noise of the output image with a lower dark current. Our proposed AFE board design is to employee the 1080p (1920×1080) CCD image sensor and its corresponding timing controller with the digital-analog converter (ADC). Our results indicate that our design has the high performance among 6 different digital brands in the low noise applications. Moreover, the CCD sensors with the different resolutions can be installed within the same socket of our AFE board, which can also simultaneously support 3 types, Bayer, Truesense, and Black/White, color filter array.

Surface Defect Detection and Classification Based on Statistical Filter and Decision Tree

Industrial quality inspection is a major issue due to the growing of market competitiveness which requires the product to be checked in terms of online defect detection. Meanwhile, labor inspection has been eliminated due to its limitation that restricts the speed of manufacturing process. Hence, automated inspection process is inevitable to preserve the industrial health and lift human function into management tasks. There are huge efforts on Automated Visual Inspection (AVI) research area, particularly in plain surfaces such as ceramics and fabrics. The inspection modeling includes statistical-based, model-based and color analysis. Most systems are well studied and tested on Charge-Coupled Device (CCD) image sensor. However, only few approaches are carried out for Complementary Metal Oxide Semiconductor (CMOS) imaging modality. This study presents an inspection scheme to detect defect in plain fabric based on statistical filter and geometrical features on CMOS-based image input. The advantage of this technology is obvious regarding to its affordable development especially for small and medium industries. We showed that it is suitable for defect inspection applications that does not require specialized lighting environment. In addition, a classification approach is developed based on decision tree framework. The result for static image shows the classification achieve 99% accuracy.

Experimental Demonstration of 4×4 MIMO Wireless Visible Light Communication Using a Commercial CCD Image Sensor

We report an experimental demonstration of 4 × 4 multiple-input multiple-output (MIMO) wireless visible light communications (VLC) using a charge-coupled device image sensor receiver instead of a photodiode receiver. An image sensor is a kind of digital camera, which is used in most mobile devices such as smart phones or laptop computers and a promising commercial candidate for a VLC receiver. The transmission distance of the experimental result is over 10 m, enough for most indoor communication applications. We expect that the MIMO VLC technique based on image sensor receivers can be widely used with the development of high-speed image sensors.

Two-dimensional single-shot tomography using a virtually imaged phased array and a spatial phase modulator

A virtually imaged phased array (VIPA) installed optical interferometer has been expanded to the two-dimensional (2D) tomography from the previous one-dimensional single-shot imaging technique with keeping the resolution and the measurement range. A single-shot measurement has been realized by a spatial phase modulator installed in the optical interferometer and tracing the delay time to pixel numbers on a 2D charge-coupled device (CCD) image sensor. The flexibility of the sample position was experimentally confirmed to be >25 mm, in relation to the VIPA coherency, for which the number of the interference order was confirmed to be 35. As a demonstration, a surface profile of stacked gauge blocks was observed. The repeatability of the surface position was 5 μm for the surface profilometry. In addition, a multilayer structure was observed using a glass plate. The experimental resolution was 53 μm when the amplified spontaneous emission light generated by the optical fiber amplifier was used for the light source. The single-shot measurement was confirmed by the 2D-CCD at a frame rate of 30 frames per second (FPS), and it provided evidence that the 2D scanless profilometry was successfully achieved using the VIPA optical device.

Recording Image with Software Setup on Dental Inspection

This paper provided an endoscopic oral observation devices, which combines with IR LED (Infrared Rays Light Emitting Diode) and IR CCD (Charge Coupled Device) image sensor to transfer the images to such monitors as television, computers and other media in order to know the situation immediately. While providing user-friendly software interface, allow the users to more easily observe the situation inside the mouth and save the file for the next patient, and even discuss their problems and the improvement progress with the dentist based on the images. The combination of special coated glass and flexible structured CCD observation pen can replace the traditional mouth mirror used by the dentist; in addition, the user can monitor the oral health under the insufficient light condition.

Theoretical Models of Modulation Transfer Function, Quantum Efficiency, and Crosstalk for CCD and CMOS Image Sensors

This paper proposes analytical models of modulation transfer function (MTF), quantum efficiency (QE), and crosstalk for charge-coupled device (CCD) and CMOS image sensors. A unified MTF model for a CCD sensor built on an epitaxial layer deposited on a highly doped substrate was developed by Stevens. The Stevens model uses sinusoidal illumination to calculate the sensor MTF degradation due to charge diffusion and sampling aperture as a function of spatial frequency. The drawback of this approach is the difficulty to evaluate analytically the electrical crosstalk distribution, which can be a good tool for predicting the detector performances, particularly for smaller pixels. In this paper, we use point-source illumination to evaluate the pixel response function (PRF). This approach is applied to the case of CMOS sensors and buried channel CCD sensors. The MTF model includes the impact of pixel size and charge diffusion. The QE model and crosstalk distribution are directly derived from the PRF expression. The models can take into account an electric field induced by a doping gradient.

A Flexible Front-End Signal Processor for High-Speed Image Sensor Readout

Abstract The High-Speed Image Pre-Processor with Oversampling (HIPPO) is a prototype image sensor readout integrated circuit designed for both high performance and enhanced flexibility. HIPPO's initial target application is the instrumentation of bufferless, column-parallel, soft x-ray Charge-Coupled Device (CCD) image sensors operating at column rates up to 10 MHz, enabling 10,000 frames-per-second (fps) video rates. HIPPO's architecture is flexible and allows design tradeoffs between speed, accuracy, and area. This architectural flexibility will enable the fast development of related image sensor and particle detector readout ICs based on HIPPO technology. HIPPO contains 16 channels, each comprising a charge amplifier, a dual-slope correlated double sampler, a sample-and-hold, a multiplexed 12b, 80 MS/s pipelined ADC (one ADC for every 4 channels), and a 480 Mb/s output serializer. HIPPO achieves 35 e-read noise at 10,000 fps for a 1 Mpixel sensor, improving to 24 e-at 5000 fps. HIPPO's charge-domain input obviates the source follower amplifier used in most CCDs and enables the implementation of a fully column-parallel CCD architecture. HIPPO was specifically designed to be flexible in both the sequencing of its operations and in its ability to accommodate input rates potentially varying over an order of magnitude.

Therapeutic Dosing of Fingolimod (FTY720) Prevents Cell Infiltration, Rapidly Suppresses Ocular Inflammation, and Maintains the Blood-Ocular Barrier

Fingolimod (FTY720) is an FDA-approved therapeutic drug with efficacy demonstrated in experimental models of multiple sclerosis and in phase III human multiple sclerosis trials. Fingolimod prevents T-cell migration to inflammatory sites by decreasing expression of the sphingosine-1 phosphate receptor normally required for egress from secondary lymphoid tissue. As a preclinical model of human uveitis, experimental autoimmune uveoretinitis permits assessment of immunotherapeutic efficacy. Murine experimental autoimmune uveoretinitis is induced by activation of retinal antigen-specific CD4(+) T cells that infiltrate the eye. High-dose fingolimod treatment administered before disease onset reduces ocular infiltration within hours of administration and suppresses clinicopathologic expression of experimental autoimmune uveoretinitis. In the present investigation of the efficacy of fingolimod treatment for established disease, single-dose treatment was effective and immunosuppressive ability was maintained through a dose range, demonstrating significant and rapid reduction in CD4(+) cell infiltration at clinically relevant therapeutic doses of fingolimod. A repeated-treatment regimen using a dose similar to that in current multiple sclerosis patient protocols significantly reduced infiltration within 24 hours of administration; importantly, repeated doses did not compromise the vascular integrity of the blood-ocular barrier. On withdrawal of fingolimod, drug-induced remission was lost and recrudescence of clinical disease was observed. These results support a strong therapeutic potential for fingolimod as an acute rescue therapy for the treatment of ocular immune-mediated inflammation.

Multimodal bio-image sensor for real-time proton and fluorescence imaging

A multimodal bio-image sensor has been devised for proton concentration (pH) imaging and filterless fluorescence imaging. A prototype of the devised sensor was fabricated using complementary metal-oxide semiconductor (CMOS) silicon integrated circuit technology. Both pH and fluorescence images were successfully obtained in the same area in real time, without the use of optical filters or gratings. In the devised sensor, a pH sensor that uses charge-coupled device (CCD) image sensor technology is combined with a filterless fluorescence detector in the same pixel. One of the applications of this sensor is intra- and extracellular recording.

Noninvasive biosensor for cathepsin L in the stratum corneum

The objective is to propose an on-site testing biosensor of cathepsin L (CatL) activity in the stratum corneum, which can be used for the evaluation of skin conditions noninvasively and easily. The biosensor comprises of a disposable test strip and a desktop-sized reader (260 × 150 × 290 mm(3), 1.9 kg), incorporating a charge-coupled device image sensor (CCD) unit to measure the reflectance of the test strip. A novel immuno-chromatographic test strip was proposed for CatL analysis in the stratum corneum. In order to realize the test strip, a colloidal gold technique was selected as the molecular recognition method for the CatL. A human skin sample was collected noninvasively by adhesive tape stripping. Based on optimal assay conditions, the sensitivity of the biosensor was evaluated. It required 10 min from a sample dropping to appear the test line on the test strip. The optical density was proportion to the CatL. Bioanalytical validation indicated that, within the biosensor's detection limit (172.2 μU/mL), its accuracy (R(2) = 0.94), and precision (CV = 15%) approach more elaborate laboratory-based analyzers. In addition, the truncated sampling-reporting cycle (<15 min) allows speedy reporting of CatL levels. It was indicated that this noninvasive and easy-to use biosensor might be a novel tool for the semi-quantitative analysis of CatL in the stratum corneum.

Residual bulk image quantification and management for a full frame charge coupled device image sensor

Residual bulk image (RBI) is significant in the KAF09000 CCD. Residual images are observed 2 h after illumination at −20C. Trap leakage and capacity are studied as a function of temperature. A flood-flush protocol is evaluated for eliminating RBI artifacts. A substrate trap fixed pattern noise is observed and is removed by dark-subtraction. An increase of dark current shot noise due to trap leakage will occur but can be minimized by deep cooling. Operating temperature targets are set as a function of target noise levels. An operating temperature of -87C for a 30 min exposure is projected to support a read noise constraint of 5 e-.

Characterization of the Influence of Moisture Content on the Morphological Features of Single Wheat Kernels Using Machine Vision

The objective of this study was to quantify changes in morphological features of kernels of western Canadian wheat classes caused by moisture increase using a machine vision system. One hundred single wheat kernels for each of eight western Canadian wheat classes were successively conditioned from 12% to 20% (wet basis) moisture contents using potassium hydroxide (KOH) concentrations which regulated relative humidity. A digital camera of 7.4 7.4-m pixel resolution with an inter-line transfer charge-coupled device (CCD) image sensor was used to acquire images of single kernels. A machine vision algorithm developed at the Canadian Wheat Board Centre for Grain Storage Research, University of Manitoba, was implemented to extract seven morphological features (area, perimeter, major axis length, minor axis length, maximum radius, minimum radius, and mean radius) from the wheat kernel images. All the seven features of Canada Western Red Spring, Canada Western Amber Durum, Canada Prairie Spring White, Canada Prairie Spring Red, Canada Western Extra Strong, Canada Western Red Winter, Canada Western Hard White Spring, and Canada Western Soft White Spring wheat kernels were significantly (a = 0.05) different as the moisture content increased from 12% to 20%. All seven features showed a linearly increasing trend with an increase in moisture content.

Quantified Temperature Effect in a CMOS Image Sensor

In recent years, CMOS image sensors (CISs) have increasingly become major players in the solid-state imaging market, a market in which charge-coupled device image sensors were once the dominant product. Exceptional circuit integration capability makes CMOS imagers suitable for implementation in a single-chip imaging system while inducing the temperature variation of an image sensor. In this paper, global and local high-leakage nonuniformities induced by on-chip temperature variations were controlled by both a Peltier junction device and on-chip resistors. Two test chips were fabricated using TSMC 0.13-?m CIS processes and TSMC 1-poly 6-metal 0.18-?m process technology, respectively. As expected, fixed-pattern noise increased with temperature. To quantify the influence of temperature, the maximum depth of an affected region was defined as DAR. The experimental results revealed that the DAR index increased with either an increase in power consumption or a space reduction between the resistor and the pixel array. The DAR index not only characterized affected regions in the experiment but also provided a valuable reference regarding temperature protection for future imager designs.

Fibre-optic coupling to high-resolution CCD and CMOS image sensors

We describe a simple method of gluing fibre-optic faceplates to complementary metal oxide semiconductor (CMOS) active pixel and charge coupled device (CCD) image sensors and report on their performance. Cross-sectional cuts reveal that the bonding layer has a thickness close to the diameter of the individual fibres and is uniform over the whole sensor area. Our method requires no special tools or alignment equipment and gives reproducible and high-quality results. The method maintains a uniform bond layer thickness even if sensor dies are mounted at slight angles with their package. These fibre-coupled sensors are of particular interest to X-ray imaging applications but also provide a solution for compact optical imaging systems.

High speed single charge coupled device Cranz-Schardin camera

This article describes an ultrahigh speed visualization system based on a miniaturization of the Cranz-Schardin principle. It uses a set of high power light emitting diodes (LEDs) (Golden Dragon) as the light source and a highly sensitive charge coupled device (CCD) camera for reception. Each LED is fired in sequence and images the refraction index variation between two relay lenses, on a partial region of a CCD image sensor. The originality of this system consists in achieving several images on a single CCD during a frame time. The number of images is 4. The time interval between successive firings determines the speed of the imaging system. This time lies from 100 ns to 10 micros. The light pulse duration lies from 100 ns to 10 micros. The principle and the optical and electronic parts of such a system are described. As an example, some images of acoustic waves propagating in water are presented.