CMOS 图像传感器的发展现状

目的　了解当前 CMOS图像传感器的发展状况 .方法　详细介绍了图像传感器的历史背景、发展现状、像素单元的结构、工作原理以及 CMOS图像传感器芯片的整体结构 ,并比较了 CMOS图像传感器和 CCD图像传感器的优、缺点 .结果　指出了 CMOS图像传感器发展趋势 .结论　 CMOS图像传感器具有美好的发展前途     

CMOS图像传感器的消噪技术

目的　介绍 CMOS图像传感器的消噪技术 .方法　比较了 CMOS图像传感器与CCD图像传感器的优缺点 ,分析了 CMOS图像传感器消噪技术的方法 ,介绍了其研制现状及发展趋势 .结果　目前采用的消噪技术有效地降低了噪声 ,提高了信噪比 .结论　预见了CMOS图像传感器消噪技术的发展趋势 .     

Wavelet diagnostics for detection of coherent structures in instantaneous turbulent flow imagery: A review

A review of work over the last decade shows that 2D wavelet techniques applied on flow imagery can provide powerful insights into the nature and lifecycle of coherent structures (the latter through wavelet movies) in turbulent shear flows. The advantage of wavelet techniques in often being able to infer the nature of coherent motion from a single image is emphasized. The techniques are first calibrated by using them on well-known results in the turbulent mixing layer. They are then applied to jets and plumes, and it is shown how off-source heating in such flows can disrupt the coherent structures in the unheated flow. A suitably reduced version of the present method, using discrete wavelet transforms on signals from a finite array of sensors, could be a useful diagnostic tool in near-real-time detection of coherent structures or patterns for the purpose of selecting appropriate control signals to the actuators in a flow-control system.     

The influence of electric-field bending on the nonlinearity ofcapacitive sensors

Three-layered electrode structures are often employed in multiple-electrode capacitive position sensors. Even when advanced algorithms and well-designed guarding electrodes are used, the electric-field-bending effect is still one of the major contributors to the nonlinearity of capacitive position sensors. In this paper, the effects of electric-field bending on linearities of five capacitive linear-position sensors have been studied based on a physical model of the capacitive sensor. It is shown that the effect of electric-field bending on linearities strongly depends on the sensor structures, and that it is significantly reduced when advanced sensor structures and algorithms are used. The results are very useful for optimizing the sensor structure according to its application     

Characterization of Wire Rope Defects with Gray Level Co-occurrence Matrix of Magnetic Flux Leakage Images

Magnetic flux leakage (MFL) techniques are used extensively for non-intrusively detecting and characterizing wire rope defects. Traditionally, MFL signals are captured with induction coil sensors. However, the output of coil sensors is related to the wire rope speed, and they can only provide the axial distribution along the wire rope. Hall sensors array are designed due to the limitation of coil sensors. In this paper, a Hall sensors array was designed to capture the MFL signals both axially and circumferentially. 30-channel data from Hall sensors are processed to compose a MFL image. A digital image process technique is introduced to preprocess the MFL image, the MFL images from different types of defects show different texture characteristics. Gray level co-occurrence matrix is utilized for feature extraction of the texture in the MFL image. Five typical eigenvalues (contrast, correlation, energy, homogeneity and entropy) are used as the inputs of back propagation (BP) networks. After training with typical samples, the BP networks show good performance in the quantitative recognition of different defects. The result of this work shows that texture analysis method for MFL image is suitable for feature extraction and quantitative detection of wire rope defects.     

Recent progress in the ZnO nanostructure-based sensors

This review focuses on the sensors based on zinc oxide (ZnO) nanostructures, which have fascinating properties including large specific surface area, good biocompatibility, high electron mobility and piezoelectricity. Due to these versatile characteristics, ZnO nanostructures can be based upon to construct gas sensors, chemical sensors, biosensors, UV sensors, pH sensors and other sensors with different sensing mechanisms. The main structures of the sensors and factors influencing the sensitivity are also discussed.     

Design Considerations for Two CCD-based Star Sensors

Solid-state image sensors such as charge-coupled devices (CCD) are being considered as the detectors in future star sensors required for the high-accuracy attitude control of spacecraft. Such detectors are adequate in respect of their electro-optical properties, and offer a fundamental advantage in geometrical stability in addition to their obvious practical advantages over other types of image scanner. However, imperfections inherent in present semiconductor processing technology necessitate complex calibration procedures if their full performance is to be realized. Other properties, such as the small image formats, complicate the optical design. Measures taken to overcome such design difficulties must be considered in relation to their impact on the strict weight, size, power and reliability specifications imposed on star sensors. These problems are illustrated with reference to two specific requirements: for a general-purpose star sensor with 1 arc second accuracy and for a 10 to 30 arc second Polaris sensor.     

Polymer–Silicon Flexible Structures for Fast Chemical Vapor Detection

Vladimir Tsukruk and co‐workers demonstrate on p. 4248 the application of plasma‐polymerized organic/silicon bimaterial structures as highly sensitive and agile chemical sensors. Owing to their unique nanoscale topology, highly crosslinked structure, and precise choice of the precursors, polymer films coated on microcantilevers exhibited record sensitivity to water vapor and other volatile organic compounds in conjunction with fast response times. The inside cover image by Brian Schrank shows the bimaterial structure deflection in the presence of a stimuli vapor.     

Research Advances in Microfiber Humidity Sensors

An overview of the numerous latest research in microfiber humidity sensors is carried out with a specific focus on measurement methods, humidity sensitive materials, probe structures, and sensing properties of different sensors. First, five mainstream measurement structures, including taper, fiber grating, coupler, resonator, and interferometer are reviewed. It is concluded that these measurement structures sense the physicochemical property variations of microfibers or sensitive films and exhibit the change of optical signal when exposed to environment. Second, the basic preparation methods, humidity‐sensing properties, and their advantages and disadvantages as humidity sensitive material are addressed. Then, the advantages and disadvantages of all the above sensing structures are also discussed and compared. Finally, the main existing problems and potential solutions of microfiber humidity sensors are pointed out.     

Flexible strain sensors fabricated using carbon-based nanomaterials: A review

Flexible strain sensors have experienced growing demand due to their several potential applications, such as personalized health monitoring, human motion detection, structural health monitoring, smart garments, and robots. Recently, several academic results have been reported concerning flexible and stretchable strain sensors. These reports indicate that the materials and design methods have an important influence on the performance of strain sensors. Carbon-based nanomaterials including carbon-based nanofibers, carbon nanotubes, graphene, and carbon black nanoparticles play a key role in the fabrication of flexible strain sensors with excellent properties. In terms of design, carbon-based nanomaterials are generally combined with polymers to maintain the flexibility and stability of a strain sensor. Various combined methods were successfully developed using different assembly structures of carbon-based nanomaterials in polymers, such as uniform mixing and ordered structures, including films, fibers, nanofiber membranes, yarns, foams, and fabrics. The working mechanisms of the flexible strain sensors, including changing the conductive network between overlapped nanomaterials, tunneling effect, and crack propagation, are also different compared with that of traditional semiconductor and metal sensors. The effects of the carbon-based nanomaterial structures in polymers on the strain sensing performance have been comprehensively studied and analyzed. The potential applications of flexible strain sensors and current challenges have been summarized and evaluated. This review provides some suggestions for further development of flexible and stretchable strain sensors with outstanding performance.     

有机/聚合物图像传感材料的研究进展

总结了有机/聚合物图像传感器材料的主要特点,对几类典型的材料体系,如共轭聚合物/C60复合体系、共轭聚合物/无机半导体纳米微粒复合体系、酞菁类和生物材料进行了重点评述,讨论了给/受体的电子结构、光致电荷转移过程、复合材料的相分离行为对传感器光敏性的影响。指出了目前有机/聚合物图像传感材料研究中亟待解决的关键科学问题。     

Optical modeling in Testbed Environment for Space Situational Awareness (TESSA)

We describe optical systems modeling in the Testbed Environment for Space Situational Awareness (TESSA) simulator. We begin by presenting a brief outline of the overall TESSA architecture and focus on components for modeling optical sensors. Both image generation and image processing stages are described in detail, highlighting the differences in modeling ground- and space-based sensors. We conclude by outlining the applicability domains for the TESSA simulator, including potential real-life scenarios.     

Equiresolution catadioptric sensors

A prominent characteristic of most catadioptric sensors is their lack of uniformity of resolution. We describe catadioptric sensors whose associated projections from the viewing sphere to the image plane have constant Jacobian determinants and so are equiresolution in the sense that any two equal solid angles are allocated the same number of pixels in the image plane. We show that in the orthographic case the catoptric component must be a surface of revolution of constant Gaussian curvature. We compare these equiresolution sensors in both the perspective and orthographic cases with other sensors that were proposed earlier for treating the uniformity-of-resolution problem.     

CCD和CMOS图像传感器的异同剖析

不管是在静止图像还是在运动图像领域,所采用的图像传感器不外乎CCD和CMOS两种,文章首先介绍了两种传感器的工艺结构和工作特点,然后给出了二者在制造工艺及性能参数等方面的主要差异,其中对两种传感器光敏单元的作用和能否实现片上系统方面作了重点强调。     

Small‐Scale Biological and Artificial Multidimensional Sensors for 3D Sensing

A vast majority of existing sub‐millimeter‐scale sensors have a planar, 2D geometry as a result of conventional top‐down lithographic procedures. However, 2D sensors often suffer from restricted sensing capability, allowing only partial measurements of 3D quantities. Here, nano/microscale sensors with different geometric (1D, 2D, and 3D) configurations are reviewed to introduce their advantages and limitations when sensing changes in quantities in 3D space. This Review categorizes sensors based on their geometric configuration and sensing capabilities. Among the sensors reviewed here, the 3D configuration sensors defined on polyhedral structures are especially advantageous when sensing spatially distributed 3D quantities. The nano‐ and microscale vertex configuration forming polyhedral structures enable full 3D spatial sensing due to orthogonally aligned sensing elements. Particularly, the cubic configuration leveraged in 3D sensors offers an array of diverse applications in the field of biosensing for micro‐organisms and proteins, optical metamaterials for invisibility cloaking, 3D imaging, and low‐power remote sensing of position and angular momentum for use in microbots. Here, various 3D sensors are compared to assess the advantages of their geometry and its impact on sensing mechanisms. 3D biosensors in nature are also explored to provide vital clues for the development of novel 3D sensors.     

A fiber-optic frequency transducer of variable pressure in gaseous and liquid media

Fiber-optic sensors of variable pressure are proposed and implemented on fiber lasers with microoptomechanical resonance structures generating in automodulation regimes. Possibilities of sound pressure monitoring in gaseous and liquid media are considered, and the sensitivity of these fiber-optic sensors is estimated.     

Clusters of Spikes in CMOS Image Sensors Irradiated by Protons and Neutrons

The distribution of pixels with high-value dark current in CMOS image sensors irradiated by protons with the energy of 1000 MeV and neutrons with a continuous spectrum simulating the energy spectrum of atmospheric neutrons is explored. Data on generation of spike clusters in the irradiated sensors and the exposure time influence on the cluster parameters are obtained.     

Intracore fiber bragg gratings for strain measurement in embedded composite structures

An intracore Bragg grating written on a photosensitive fiber core is used for strain measurement in composite specimens under load. The strain information is directly related to the absolute change in the Bragg-reflected wavelength. Fiber Bragg grating (FBG) sensors (fibers with intracore gratings) are thus sensitive to strain that is caused by changes in temperature as well as to load-induced changes. Thus these sensors can be made to be independent of source intensity variations and losses. FBG sensors used for load-induced strain sensing in composite structures and the effects of temperature on them are discussed. A detailed account of the use of such embedded structures as self-monitoring nondestructive testing devices is given.     

特殊结构露点传感器的校准特点

露点仪、露点传感器作为环境湿度的检测仪器,广泛使用于工农业生产、工业自动化和生活的各个领域。本文通过对露点传感器校准的现状分析,指出了目前的校准方法中存在的尚不具体明确之处。本文分析了特殊露点传感器结构原理,由此改进了特殊结构露点传感器的校准方法。     

An object detection strategy for uncooled infrared imagery

Abstract

An overall strategy for the very difficult problem of object detection using uncooled infrared (UCIR) sensors is discussed. The UCIR sensors are based on micro-bolometer technology and thus differ significantly from cooled infrared sensors that employ photon-counting detectors. As such, UCIR imagery tends to be very low contrast, since the sensor operates over a broad spectral band; and blurry, because of the long integration times. Ideally, the UCIR imagery would be preprocessed using an appropriate image reconstruction/restoration algorithm. If the sources of image degradation are understood and lend themselves to accurate modelling, the image reconstruction can be solved as an inverse problem. Most often this is not the case and the problem is solved using minimization approaches, such as blind deconvolution. Because image reconstruction/restoration approaches tend to be very throughput intensive, they are rarely performed in a tactical environment. More typically, a detection algorithm is applied directly to the UCIR imagery. In this paper, Local Singular Value Decomposition (LSVD) is evaluated for anomaly detection. LSVD uses local statistics to identify anomalous regions and is very good at identifying local texture differences; it appears to work quite well on UCIR imagery. Target detection results are presented for a simulated data set.