Charge-coupled Device Linear Array Research Articles

A two-stage framework for pixel-level pavement surface crack detection

Surface crack is one of the most common distresses of pavement structure, impacting its serviceability and sustainability. Over the past decade, many efforts have been devoted to developing computer vision-based models (e.g., image processing- or deep learning-based) for the automatic detection of pavement surface crack. However, there is a great gap between the public image data taken by the phone or other portable devices and the real-world image data acquired by the linear array charge-coupled device (CCD) camera, which usually is high resolution and contains limited crack pixels per image. To improve the pavement surface crack detection efficiency and accuracy in engineering practice, we propose a novel two-stage framework for automatic pavement surface detection at the pixel level. In stage I, the images concluding pixel cracks are selected using a convolutional neural network (CNN)-based classification network. In stage II, the selected images are processed with our proposed separation-combination strategy and the second version of crack transformer (CTv2) for pavement surface crack detection at the pixel level. Comprehensive experimental investigation and comparison have been conducted on training performance and visualization results, validating the superiority of the developed framework. It paves the way for the large-scale application of automatic pavement crack detection in an efficient manner.

Deflection Basin Detection of Pavements Based on Linear Array Charge-Coupled Device (CCD) Photoelectric Sensors

Deflection is an important indicator of the overall pavement strength, and it is generally detected using the Falling Weight Deflectometer (FWD). In response to the shortcomings of FWD in use, a pavement deflection detection method based on a linear array charge-coupled device (CCD) photoelectric displacement sensor is proposed. Firstly, a detailed description is given of the working principle of the deflection detection photoelectric sensor for the center point of the deflection basin and other points. Secondly, a photoelectric displacement sensor using linear array CCD deflection detection is designed, including a laser, CCD signal processing module, CCD and its driver module, and upper computer communication module. Among them, the EPF10K20TC144-4 device of the FLEX 10K series from ALTERA company is used to generate CCD driving pulses; Two DM54LS245 are selected as the driving interface for CCD photoelectric sensors, and corresponding filtering and signal amplification circuits are designed to address the noise problem of CCD photoelectric signal injection. Finally, the fixed threshold method separates the background and image signals in the CCD photoelectric signal, and the microcontroller is connected to the serial port of the upper computer through the MAX232 chip. The displacement measurement experiment uses the designed linear array CCD photoelectric displacement sensor. The results show that the road deflection basin detection method by the linear array CCD photoelectric displacement sensor fully meets the actual detection requirements and can obtain dynamic deformation information of the tested road surface. It is helpful for a detailed understanding of the changes in the deflection basin of the road surface under load.

Sugarcane Node Detection Method Based on Photoelectric Sensor Vertical Projection Signal Processing

Highlights A linear array CCD sensor is utilized to obtain the contour signal of the vertical projection of the sugarcane. A method is provided for continuously identifying and locating sugarcane nodes. Examines the impact of scan speed and illumination on the accuracy of identification. The method performs well regarding identification rate, precision, and efficiency. Abstract. In order to achieve continuous and dynamic detection of sugarcane nodes, improve the automatic production efficiency of pre-cut sugarcane seed, and lower the cost of mechanized sugarcane production, a detection method based on linear array charge-coupled device (CCD) photoelectric sensor signal processing was developed. Firstly, the mechanical drive unit was controlled to drive the photoelectric detection system to acquire the signal of the vertical projection of the sugarcane profile. The projection information was then binarized into profile information using the Otsu algorithm. The profile signal was then decomposed using a variable mode decomposition algorithm optimized based on the sparrow search algorithm, and the component reflecting the node content was regarded as the feature signal. Finally, the position of the wave peaks above the judgment threshold in the normalized feature signal was considered the position of the sugarcane nodes. One-way and two-way experiments were conducted to investigate the effects of scan speed and illuminance on identification precision. The results showed that the identification rate, average response time, and average error values were 98.40%, 0.13 s, and 1.36 mm at a scan speed of 75 mm/s and an illuminance of 91.91 lx. Compared to other node identification methods discussed in this article, the proposed method has a high identification rate and accuracy with a high response speed, which can improve the automation efficiency of sugarcane seed production. Keywords: Identification accuracy, Non-contact detection, Photoelectric sensor, Precision agriculture, Seed production, Signal processing, Sugarcane node, Variational mode decomposition.

Obtaining Unfolded Image for Surface of Wire Rope Based on Image Processing and Splicing

A system of obtaining image of surface of wire rope is designed in this paper. Three linear-array charge-coupled device industrial cameras are used, separated by 120 degrees in the same plane. The acquisition is realized by receiving the synchronous pulse transmitted by the encoder. Considering that the wire rope is bent due to gravity, this paper restores the wire rope to the straightened state through image processing. The wire rope is then separated from the image. In order to obtain a complete surface unrolling diagram, this paper firstly corrects the projection of curved surface of image of the wire rope. Three unrolling diagrams of surface of wire rope with different angles are obtained, and then, the surface development image with different directions is aligned in axial and circumferential directions, respectively. At last, weighted average algorithm is used for image fusion. The experimental results show that the method proposed in this paper can obtain a complete, intuitive and non-dislocation surface development image of wire rope.

Micro-Distortion Detection of Lidar Scanning Signals Based on Geometric Analysis

When detecting micro-distortion of lidar scanning signals, current hardwires and algorithms have low compatibility, resulting in slow detection speed, high energy consumption, and poor performance against interference. A geometric statistics-based micro-distortion detection technology for lidar scanning signals was proposed. The proposed method built the overall framework of the technology, used TCD1209DG (made by TOSHIBA, Tokyo, Japan) to implement a linear array CCD (charge-coupled device) module for photoelectric conversion, signal charge storage, and transfer. Chip FPGA was used as the core component of the signal processing module for signal preprocessing of TCD1209DG output. Signal transmission units were designed with chip C8051, FT232, and RS-485 to perform lossless signal transmission between the host and any slave. The signal distortion feature matching algorithm based on geometric statistics was adopted. Micro-distortion detection of lidar scanning signals was achieved by extracting, counting, and matching the distorted signals. The correction of distorted signals was implemented with the proposed method. Experimental results showed that the proposed method had faster detection speed, lower detection energy consumption, and stronger anti-interference ability, which effectively improved micro-distortion correction.

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.

High-temperature fiber-optic Fabry-Perot interferometric sensors.

A photonic crystal fiber (PCF) based high-temperature fiber-optic sensor is proposed and experimentally demonstrated. The sensor head is a Fabry-Perot cavity manufactured with a short section of endless single-mode photonic crystal fiber (ESM PCF). The interferometric spectrum of the Fabry-Perot interferometer is collected by a charge coupled device linear array based micro spectrometer. A high-resolution demodulation algorithm is used to interrogate the peak wavelengths. Experimental results show that the temperature range of 1200 °C and the temperature resolution of 1 °C are achieved.

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.

Investigation of Digital Sun Sensor Technology with an N-Shaped Slit Mask

Nowadays sun sensors are being more widely used in satellites to determine the sunray orientation, thus development of a new version of sun sensor with lighter mass, lower power consumption and smaller size it of considerable interest. This paper introduces such a novel digital sun sensor, which is composed of a micro-electro-mechanical system (MEMS) mask with an N-shaped slit as well as a single linear array charge-coupled device (CCD). The sun sensor can achieve the measurement of two-axis sunray angles according to the three sun spot images on the CCD formed by sun light illumination through the mask. Given the CCD glass layer, an iterative algorithm is established to correct the refraction error. Thus, system resolution, update rate and other characteristics are improved based on the model simulation and system design. The test of sun sensor prototype is carried out on a three-axis rotating platform with a sun simulator. The test results show that the field of view (FOV) is ±60° × ±60° and the accuracy is 0.08 degrees of arc (3σ) in the whole FOV. Since the power consumption of the prototype is only 300 mW and the update rate is 14 Hz, the novel digital sun sensor can be applied broadly in micro/nano-satellites, even pico-satellites.

Rigorous Photogrammetric Processing of HiRISE Stereo Imagery for Mars Topographic Mapping

High-resolution (submeter) orbital imagers have opened up new possibilities for Mars topographic mapping with unprecedented precision. While the typical sensor model for Martian orbiters has been the linear-array charge-coupled device (CCD), the High-Resolution Imaging Science Experiment (HiRISE) instrument is based on a more complicated structure involving a combination of 14 separate linear-array CCDs. To take full advantage of this high-resolution capability without compromising imaging geometry, we have developed a rigorous photogrammetric model for HiRISE stereo image processing in which third-order polynomials are used to model the change in exterior-orientation parameters over time. A coarse-to-fine hierarchical matching approach was developed, and its performance was evaluated based on manually matched image points and manually measured features for a test area at the Mars Exploration Rover Spirit landing site. Using automatically selected tie points, we performed bundle adjustment (BA) to improve the accuracy of image pointing data and remove or reduce inconsistencies between the stereo pair and inconsistencies between overlapping CCDs in the same image mosaic. A method for the incorporation of jitter terms into the BA was developed and proved to be effective. We created a 1-m-resolution digital elevation model and an orthophoto using this methodology and compared them with topographic products from the U.S. Geological Survey.

Design and evaluation of a visible-to-near-infrared electronic slitless spectrograph

Most commercial diffraction grating based spectroscopic devices employ entrance slit and optics based on the conventional Czerny–Turner (CT) configuration. A study was undertaken to design and develop a novel lab-scale electronic slitless spectrograph (ESS). The developed ESS has a tuneable spectral detectable range from approximately 450–1100 nm and a scanning speed of 0.7 s per spectrum. It works under reflectance mode with external illumination. System design employed a fibre optic waveguide as the probe, several focusing and collimating lenses, a plane reflection diffraction grating and a linear array charge-coupled device (CCD) detector. A method using a single-mode diode laser to calibrate the wavelength and pixel relationship was applied to obtain a least-square regression equation. An argon lamp was used to validate the calibrated wavelength equation and a maximum wavelength error of 1.95 nm was reported. A procedure to estimate the instrumental optical band-pass using laser spectra with a limited number of sampling points was examined. An optical band-pass expressed as full-width-at-half-maximum (FWHM) of 6.71 nm was estimated using the proposed method on the spectrum of the single-mode diode laser. The test results suggest that the developed ESS system has the potential to serve as a rugged and cost-effective spectroscopic device for routine inspection. The prototype consists of no moving parts and the complete assembly measures 30 cm × 25 cm × 15 cm, which can be greatly reduced upon further development.

Optical sensor interrogation with a blazed fiber Bragg grating and a charge-coupled device linear array.

We present what is to our knowledge the first comprehensive investigation of the use of blazed fiber Bragg gratings (BFBGs) to interrogate wavelength division multiplexed (WDM) in-fiber optical sensor arrays. We show that the light outcoupled from the core of these BFBGs is radiated with sufficient optical power that it may be detected with a low-cost charge-coupled device (CCD) array. We present thorough system performance analysis that shows sufficient spectral-spatial resolution to decode sensors with a WDM separation of 75 rhom, signal-to-noise ratio greater than 45-dB bandwidth of 70 nm, and drift of only 0.1 rhom. We show the system to be polarization-state insensitive, making the BFBG-CCD spectral analysis technique a practical, extremely low-cost, alternative to traditional tunable filter approaches.

Compact focusing von Hamos spectrometer for quantitative x-ray spectroscopy

A compact focusing crystal spectrometer based on the von Hamos scheme is described. Cylindrically curved mica and graphite crystals with a radius of curvature of R=20 mm are used in the spectrometer. A front illuminated charge-coupled device (CCD) linear array detector makes this spectrometer useful for real-time spectroscopy of laser-produced plasma x-ray sources within the wavelength range of λ=1.8–10 Å. Calibration of crystals and the CCD linear array makes it possible to measure absolute photon fluxes. X-ray spectra in an absolute intensity scale were obtained from Mg, Ti, and Fe laser-produced plasmas, with a spectral resolution λ/δλ=800–2000 for the mica and λ/δλ=200–300 for graphite crystal spectrometers. The spectrometer has high efficiency in a wide spectral range, it is compact (40 mm diam, 150 mm length), easy to align, and flexible. The spectrometer is promising for absolute spectral measurements of x-ray radiation of low-intensity sources (femtosecond laser-produced plasmas, micropinches, electron-beam–ion-trap sources, etc.).

Novel two-dimensional position measurement method with linear array charge-coupled device

A new method for position measurement with CCDs is pre- sented. Two-dimensional position coordinates can be precisely mea- sured in a short time with a special optical system having two linear array CCDs. The experimental setup with a signal-processing unit is described in detail. Experimental results are shown, and the sources of error are analyzed. © 1998 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(98)00509-1)

Noncontact microstrain measurements in orthodontic wires.

A technique is presented that allows for highly sensitive and highly accurate measurements of microstrain in biomaterials. It is particularly useful for measuring strains in materials where the use of conventional extensometers or strain gauges is impracticable, such as reinforcement fibers and orthodontic wires and in hostile environments. The technique is based on the well known technique of observing translating laser speckle with a linear-array charge-coupled device (CCD) camera. However, it employs a relatively new data processing algorithm involving a two-dimensional frequency transform of the data. Advantages of the technique include: insensitivity to slow surface microstructure changes, insensitivity to zero-mean noise processes, compact design, modest resolution requirements, and the fact that it is truly noncontact. Strain rate measurements were made on an 0.028-gauge round stainless steel orthodontic wire as an example of this technique. The Young's modulus of the wire based on the speckle technique was 2.04 x 10(11) Nm(-2), which is very close to the textbook value.

Application of a CCD linear array camera in the quantification of tissue staining: NBT detection in ischaemic myocardium

A method was developed to quantify the intensity of tissue staining using a CCD (charge-coupled device) camera. Reflection spectra of NBT-stained (nitro-blue tetrazolium-stained) and unstained myocardium were recorded via fibre optics coupled to a CCD camera, connected to a microcomputer. The calculation of the intensity of staining was based on evaluation of the NBT-related changes of the reflectance spectrum. In each of six anaesthetized sheep, global ischaemia was induced by cross-clamping of the aorta. The hearts were removed and incubated at 35 degrees C. At predetermined times two sections of ventricular myocardium were taken, one of which was then stained with NBT, the other being left unstained. Evaluation of the reflectance spectra from stained sections during the first phase of ischaemia showed a slight loss of NBT colour intensity followed by a more rapid loss of staining until the values of the unstained sections were reached.

X-ray transmission grating spectrometer with CCD detector for laser plasma studies

A program is under way to develop methods and instrumentation based on charge-coupled device (CCD) sensors for hot plasma diagnostics. We have developed a new X-ray spectrometer in which a freestanding X-ray transmission grating is coupled to a CCD linear array detector with electronic digitized readout replacing film and its wet processing. This instrument measures time-integrated pulsed X-ray spectra with moderate spectral resolution (δλ ≤ 0.6 nm) over a broad spectral range (0.3–2 keV) with high sensitivity, linearity, and large dynamic range. The performance of the device was tested using laser plasma as the X-ray source.

Imaging system for morphometric assessment of absorption or fluorescence in stained cells.

An image acquisition and processing system has been developed for quantitative microscopy of absorption or fluorescence in stained cells. Three different light transducers are used in the system to exploit the best characteristics of these sensors for different biological measurements. A digital scanner, in the form of a linear array charge-coupled device (CCD), acquires data with high spatial and photometric resolution. A color (RGB) camera is employed when spectral information is required for the segmentation of cellular subcomponents. An image-intensified charged-injection device (CID) camera provides for very low light intensity measurements, primarily for fluorescence-labeled cells. Properties of these transducers, such as contrast transfer function, linearity, and photo-response nonuniformity, have been measured. Two dedicated image processing units were incorporated into the system. The front-end processor, based on a digital signal processor, provides functions such as object detection, raw image calibration, compression, artifact removal, and filtering. The second image processor is associated with the frame memory and includes a histogram processor, a dedicated arithmetic logic unit for image processing functions, and a graphics module for one-bit overlay functions. An interactive program was developed to acquire cell images and to experiment with a range of segmentation algorithms, feature extractions, and other image processing functions. The results of any image operation are displayed on the video monitor. Once a desired processing sequence is determined, the sequence may be stored to become part of a command library and can be executed thereafter as a single instruction.

<title>Integrated Optoelectronic Silicon Devices for Optical Signal Processing and Communications</title>

Integrated optoelectronic devices will be considered in which optical fibers are coupled to optical channel waveguides and in which both optical slab and channel waveguides are coupled to detectors. Use of Si02/Si substrates allows formation of low loss waveguides, smooth V-groove channels for both channel waveguides and fiber support channels and sophisticated detector configurations such as charge-coupled device (CCD) linear arrays. We will discuss a slab waveguide-CCD detector coupling structure which has been experimentally characterized by a high degree of uniformity along the linear array, minimal excessive optical scattering and very low charge transfer inefficiency. Coupling of light from optical fibers to channel waveguides and from an array of channel waveguides to a CCD linear array is demonstrated. Applications of the various device structures considered to integrated optical spectrum analysis, optical transversal filtering, and time multiplexing of a number of fiber optical communication channels are discussed.