Compact Image Research Articles

An Area-Efficient and Low-Power Logarithmic A/D Converter for Current-Mode Sensor Array

This paper presents an area-efficient and low-power current-mode logarithmic analog-to-digital converter (LADC) that can be potentially used for large-scale CMOS sensor array applications. The core of the proposed LADC consists of a novel analog functional block and a reference transistor working in the subthreshold region, which encodes the input sensor currents into logarithmically compressed voltage outputs. The LADC core has been implemented in standard 0.18 ¿m CMOS process with a total area of 55 ¿m × 55 ¿m and a power consumption of less than 9.7 ¿W. A 7-bit digital counter and an external discrete ramp generator, typically shared among all sensor unit cells in the future sensor array implementation, complete the LADC configuration. Measurement results have presented a dynamic range of 80 dB with 5 KS/s conversion rate. The proposed LADC is ideally suited for compact and low-power CMOS biomedical sensor arrays or CMOS image sensor applications.

Effect of Silicon Sol on Anodic Oxidation Film of Titanium Alloys

In this paper, the anodic oxidation film was prepared in the 1~3mol/L NaAlO2 solution with and without silicon sol added. The film thickness, high temperature oxidation resistance, corrosion resistance, and SEM image, element composition in the film were investigated. The results show that there were obvious improvement in high temperature oxidation resistance and corrosion resistance of the film on titanium alloys after adding silicon sol into the NaAlO2 solution, and with the sol percentage in the solution increased, the foregoing protection abilities of the anodic oxidation film became better, while the film thickness was little affected with the sol percentage difference. The reason was discussed and the effective factor was the silicon composition and more even and compact image in the film.

GRAIN GROWTH AND DENSITY DISTRIBUTION OF THE YOUNGEST PROTOSTELLAR SYSTEMS

We present dust opacity spectral indexes (beta) of the youngest protostellar systems (so-called Class 0 sources), L1448 IRS 2, L1448 IRS 3, and L1157, obtained between 1.3 mm and 2.7 mm continua, using the Combined Array for Research in Millimeter-wave Astronomy (CARMA). The unprecedented compact configuration and image fidelity of CARMA allow a better detection of the dust continuum emission from Class 0 sources, with a less serious missing flux problem normally associated with interferometry. Through visibility-modeling at both 1.3 mm and 2.7 mm simultaneously, as well as image- and visibility-comparison, we show that beta of the three Class 0 sources are around or smaller than 1, indicating that dust grains have already significantly grown at the Class 0 stage. In addition, we find a radial dependence of beta, which implies faster grain growth in the denser central regions and/or dust segregation. Density distributions of the Class 0 sources are also addressed by visibility-modeling.

Age‐related differences in the time it takes to form auditory images of broadband noises.

When correlated noises are presented over earphones to the two ears, listeners typically form a fused compact image of the noise. However, when the noises presented to the two ears are independent, listeners tend to hear two noises: one on the left and the other on the right. In Experiment 1 we determined the minimum duration required to form auditory images by asking listeners to distinguish between a 1‐s presentation of independent noises to the left and right ears, and another 1‐s presentation in which the noise was correlated for x ms before switching to two independent noises. In Experiment 2, one of the noises was correlated throughout the 1‐s presentation; the other started off uncorrelated before switching to correlated. Younger adults performed better than older adults in both experiments. However, the performance of younger adults was better in Experiment 2 than in Experiment 1, whereas the reverse was true for older adults. The implications of these results for age‐related changes in auditory scene analysis will be discussed. [This work was supported by the National Natural Science Foundation of China, the Natural Sciences and Engineering Research Council of Canada, and the Canadian Institutes of Health Research.]

Development of a compact x-ray particle image velocimetry for measuring opaque flows

A compact x-ray particle image velocimetry (PIV) system employing a medical x-ray tube as a light source was developed to measure quantitative velocity field information of opaque flows. The x-ray PIV system consists of a medical x-ray tube, an x-ray charge coupled device camera, a programmable shutter for a pulse-type x ray, and a synchronization device. Through performance tests, the feasibility of the developed x-ray PIV system as a flow measuring device was verified. To check the feasibility of the developed system, we tested a tube flow at two different mean velocities of 1 and 2 mm/s. The x-ray absorption of tracer particles must be quite different from that of working fluid to have a good contrast in x-ray images. All experiments were performed under atmospheric pressure condition. This system is unique and useful for investigating various opaque flows or flows inside opaque conduits.

Enhanced output current density of an active-matrix high-efficiency electron emission device array with 13.75μmpixels

An active-matrix array of high-efficiency electron emission device (HEED) with a sufficient output density has been developed for the use as imaging probe in a high-gain avalanche rushing amorphous photoconductor target. Previously, it was demonstrated that a prototyped image sensor with 20×20μm2pixels could pick up a high definition image with an ultrahigh sensitivity under low-light-level condition. Based on it, an efficient active-matrix HEED with 13.75×13.75μm2pixels is fabricated for pursuing higher sensitivity and resolution. The improvement in the device isolation method enables to enlarge the relative emitting area, and then the emission current density per pixel reaches 3.6A∕cm2 that is about four times of that obtained from the previous one. The active-matrix HEED array with small pixels is available for application to the compact ultrahigh-sensitivity image sensor without affecting on the image definition.

Auto-focusing actuator and camera module including flexible diaphragm for mobile phone camera and wireless capsule endoscope

Recent cellular phones have high-resolution, compact digital camera modules that have several millions of pixels. Although being small, such several mega-pixel camera modules definitely need to be able to execute auto-focusing and/or optical zooming in order to obtain precise images. Hence, image photographing devices having driving mechanisms that can move a lens group in the direction parallel to an optical axis have appeared such as piezoelectric type, linier motor type, and voice coil motor type. Although these technologies are already popular in existing digital cameras, driving mechanism for camera modules in cellular phones needs to be extremely improved because their requirements are totally different from usual digital cameras. Compact image photographing devices, which are installed in mobile apparatuses, should improve portability by reducing their sizes and weights and increase use-time of a battery by reducing power consumption. Weakened suspension (e.g. thickness is 0.02 mm or less) in order to minimize an elastic coefficient for drastic decrease of driving current frequently occurs permanent step-out of a lens group by plastic deformation of the metal suspensions when it comes to getting shocks from accidental drops of a handset. The proposed auto-focusing actuator using conductive polyimide as a flexible diaphragm satisfies these requirements of ultra slim cell phones. This polyimide suspension shows ultimate toughness when it comes to drop-test of cell phones. This actuator also shows high performance quite enough for several mega-pixel camera modules for ultra slim cellular phones; the moving range is up to 0.35 mm, the DC sensitivity is 0.2 mm/140 mA, and the resistance at the terminal is 22 Ohm, whereas the aperture is 6.8 mm, and the overall size is 10 × 10 × 3.95 mm. Most of all, the robustness against drop and shock has been dramatically increased, with no change of reliability under high temperature and high humidity condition, because of the flexibility of the conductive polyimide suspension.

感覚共有と小型人型ロボット操縦のためのコンパクトな画像安定化システム(機械力学,計測,自動制御)

感覚共有と小型人型ロボット操縦のためのコンパクトな画像安定化システム(機械力学,計測,自動制御)

Development of ultrahigh-sensitivity compact image sensor with field emitter array and avalanche photoconductor

Development of ultrahigh-sensitivity compact image sensor with field emitter array and avalanche photoconductor

Artificial compound eye zoom camera

We demonstrate a highly compact image capturing system with variable field of view but without any mechanically moving parts. The camera combines an ultra-thin artificial apposition compound eye with one variable focal length liquid lens. The change of optical power of the liquid lens when applying a voltage results in a change of the magnification of the microlens array imaging system. However, its effect on focusing of the individual microlenses can be neglected due to their small focal length.

Parametrization of the Teichmüller space of bordered surface NEC groups

A non-Euclidean crystallographic group Γ (NEC group, for short) is a discrete subgroup of isometries of the hyperbolic plane Open image in new window , with compact quotient space Open image in new window /Γ. These groups uniformize Klein surfaces, surfaces endowed with dianalytic structure. These surfaces can be seen as a generalization of Riemann surfaces.

Compact image stabilization system using camera posture information

AbstractA teleoperated robot that works in unstructured environments such as disaster sites is mainly controlled based on images obtained from cameras mounted on the robot. Because the robot runs on rough terrains, the images from the mounted camera are nonsteady ones. These nonsteady images will make it difficult for the operator to understand the surrounding information and will cause the camera motion sickness. We have developed an image stabilization system using camera posture information for a mobile robot that moves on uneven terrains. Because the camera posture information is detected by a three‐dimensional‐motion sensor separately from the camera image, this system works even in bad light condition environments and is robust for light condition changes. The wide‐field‐of‐view images obtained by the fish‐eye‐lens camera are used to handle a large‐amplitude disturbance. The sphere mapping and the image shifting of a region of © 2008 Wiley Periodicals, Inc.

Compact Ultrasensitive FEA Image Sensor with HARP Target

Compact Ultrasensitive FEA Image Sensor with HARP Target

Development of an Ultra-highly Sensitive Image Sensor with a Field Emitter Array and a HARP Film

A 640×480 pixel image sensor, which consisted of an integrated field emitter array (FEA) equipped with an active drive circuit and a high-gain avalanche rushing amorphous photoconductor (HARP) film, in close proximity to each other, was fabricated and tested as a step toward the development of ultrahigh-sensitivity compact image sensors. Our experimental results revealed that the prototype sensor provided both high sensitivity due to the avalanche multiplication effect of the HARP film and sufficient resolution as a VGA image sensor.

Laparoscopic treatment of a calcium fluorophosphate stone within a seminal vesicle cyst

Stones in the seminal vesicles are extremely rare. We present a 62-year-old patient with a stone within a seminal vesicle cyst, who was cured by laparoscopic treatment. The operative time was 80 min, and the estimated blood loss was 90 mL. Scanning electron microscope examination of the stone showed a compact crystal image externally and sparse spherical crystal structure in kernel. Composition of the stone was calcium fluorophosphate on X-ray diffractometer. The follow-up time was 15 months with no recurrence of cyst or stone. To our knowledge, this case is the first to describe laparoscopic removal of a stone within a seminal vesicle cyst, and the first to describe calcium fluorophosphate as the composition of seminal vesicle stones.

Inversion of deep-sea vertical electric soundings using the correlational similarity method

A method is proposed for the inversion of marine vertical electric sounding (VES) data in a tomographic approximation. A 2.5-D inversion is based on the correlational similarity method; this method is a natural stabilizer of the solution and provides the most compact image of an anomaly carrier. The algorithm possesses a high convergence rate. The inversion reduces to the expansion of anomalous stresses in orthogonal reference functions that are spatial focusing coefficients of a VES configuration. The coefficients were calculated with the help of a new method of contracting mappings allowing one to construct efficient algorithms for calculating electromagnetic fields on a dense spatial grid. Results of experimental in situ data inversion refined the morphology of deep-sea polymetallic sulfides of the Logachev-1 orefield in the Atlantic Ocean.

Level Set Hyperspectral Image Classification Using Best Band Analysis

We present a supervised hyperspectral classification procedure consisting of an initial distance-based segmentation method that uses best band analysis (BBA), followed by a level set enhancement that forces localized region homogeneity. The proposed method is tested on two hyperspectral images of an urban and rural nature. The proposed method is compared to the maximum likelihood (ML) method using BBA. Quantitative results are compared using segmentation and classification accuracies. Results show that both the initial classification using BBA features and the level set enhancement produced high-quality ground cover maps and outperformed the ML method, as well as previous studies by the authors. For example, with the compact airborne spectrographic imager image, the ML method resulted in accuracies les95.5%, whereas the level set segmentation approach resulted in accuracies as high as 99.7%.

Compact and self-aligned all-optical image correlator based on third-harmonic generation

We demonstrate a compact optical correlator using a diffractive optical element (DOE) beam splitter for 2D optical image processing. Image frequency conversion and correlation are demonstrated using third-harmonic generation (THG) in an organic film with a 1550 nm femtosecond laser. Spatial and temporal alignment of the femtosecond pulses are obtained by imaging the DOE onto the organic film.

Adaptive-Quantization Digital Image Sensor for Low-Power Image Compression

The recent emergence of new applications in the area of wireless video sensor network and ultra-low-power biomedical applications (such as the wireless camera pill) have created new design challenges and frontiers requiring extensive research work. In such applications, it is often required to capture a large amount of data and process them in real time while the hardware is constrained to take very little physical space and to consume very little power. This is only possible using custom single-chip solutions integrating image sensor and hardware-friendly image compression algorithms. This paper proposes an adaptive quantization scheme based on boundary adaptation procedure followed by an online quadrant tree decomposition processing enabling low power and yet robust and compact image compression processor integrated together with a digital CMOS image sensor. The image sensor chip has been implemented using 0.35-mum CMOS technology and operates at 3.3 V. Simulation and experimental results show compression figures corresponding to 0.6-0.8 bit per pixel, while maintaining reasonable peak signal-to-noise ratio levels and very low operating power consumption. In addition, the proposed compression processor is expected to benefit significantly from higher resolution and Megapixels CMOS imaging technology

１インチ２５６×１９２画素アクティブ駆動型ＨＥＥＤ冷陰極ＨＡＲＰ撮像板

We made an active-matrix high-efficiency electron emission device (HEED) that had scanning driver circuits fabricated with conventional MOS planer technology.A 1-in 256x192 pixel image sensor,consisting of the active-matrix HEED and a high-gain avalanche rushing amorphous photoconductor (HARP) target,was fabricated and tested as a step toward the development of ultrahigh-sensitivity compact image sensors with a large number of pixels.The experimental results show that the prototype sensor can be used to obtain clear images even under dark lighting conditions,such as in moonlight,and that the active-matrix HEED is a promising highspeed image pick-up device.