Instantaneous Imaging Research Articles

Electret Film-Enhanced Triboelectric Nanogenerator Matrix for Self-Powered Instantaneous Tactile Imaging

We report the first self-powered electronic skin that consists of light-emitting diode (LED) and triboelectric nanogenerator (TENG) arrays that can be utilized for spatially mapping applied instantaneous-touch events and tracking the movement location of the target object by recording the electroluminescent signals of the LEDs without external power sources. The electret film-based TENG can deliver an open-circuit voltage of about -1070 V, a short-circuit current density of 10 mA/m(2), and a power density of 288 mW/m(2) on an external load of 100 MΩ. The LEDs can be turned on locally when the back surface of the active matrix is touched, and the intensity of the emitted light depends on the magnitude of the applied local pressure on the device. A constructed active matrix of the LED-TENG array (8 × 7 pixels) can achieve self-powered, visual, and high-resolution tactile sensing by recording the electroluminescent signals from all of the pixels, where the active size of each pixel can be decreased to 10 mm(2). This work is a significant step forward in self-powered tactile-mapping visualization technology, with a wide range of potential applications in touchpad technology, personal signatures, smart wallpapers, robotics, and safety-monitoring devices.

Analysis of forest fires in Northeast China from 2003 to 2011

Wildfires, a common disturbance in ecosystems, can be an immediate and dominant source of interannual carbon variability. In this study, we used an instantaneous Moderate Resolution Imaging Spectroradiometer (MODIS) global disturbance index algorithm to explore continuous spatiotemporal patterns of forest fires in Northeast China. The forest fires that were sensed remotely were then validated by field records. The findings suggest that the disturbance index is effective in locating forest fires in Northeast China, as evidenced by a close match with field fire records. We found that the incidence of forest fires was closely linked to extreme conditions of climate warming and drought, and more fires occurred in dry years than in wet years. Among different forest types, shrublands, mixed forest, and deciduous needleleaf forests were more prone to wildfires because of their fire regime characteristics. The study demonstrates that the algorithm was effective in detecting forest fires from 2003 to 2011 in Northeast China, providing fundamental data for forest inventory and large-scale ecological applications.

Instantaneous microwave imaging with time‐domain measurements for breast cancer detection

A breast cancer imaging system with time-domain measurements is proposed. This system is based on complementary metal-oxide semiconductor circuits such that it is very cost-effective and the image is acquired in a very short time. It consists of ultra-wideband transceivers and a master controller for system control and data collection. Simulation results with a 3D FDTD hemi-spherical breast model show the proposed system can reconstruct the breast image in the presence of possible disturbances such as clock skew, clock jitter, and white noise.

Instantaneous 2D imaging of temperature in an engine cylinder with flame combustion

To improve internal combustion engines, it is critical to measure the temperature distribution of their walls. However, only a few studies have quantitatively visualized the instantaneous temperature distribution of a wall exposed to flames. Lifetime-based temperature imaging was performed using a simple measurement system consisting of a non-intensified high-speed CMOS camera, a pulsed UV laser, and a phosphor coated quartz glass covered with a thin metal film. The uncertainty in the temperature measurement was ±2.0°C for measurements of uniform temperature fields in the range 40–250°C. Single-shot wall temperature measurements were demonstrated for combustion by flames in an engine cylinder. This enabled inhomogeneous temperature distributions in the engine with or without flames to be visualized. Even under motoring conditions, there was a large temperature gradient across the side window at the highest position of the piston. The side window temperature decreased near the intake valve. The intake gas flow had a cooling effect and the intake pressure affected the temperature distribution. The engine speed and the coolant temperature increased the magnitude of temperature but they did not affect the overall temperature distribution, i.e. the spatial distribution and the spatial gradient of the temperature. The instantaneous temperature of the top of the piston was visualized in the transient process after firing had commenced.

THREE DIMENSIONAL RADAR COINCIDENCE IMAGING

Two dimensional (2D) radar coincidence imaging is an instantaneous imaging technique which can obtain 2D focused highresolution images using a single pulse without the limitation to the target relative motions. This paper extends the imaging method to three dimensions. Such a three-dimensional (3D) radar imaging technique does not rely on Doppler frequency for resolution and has an extremely short imaging time (shorter than a pulse width), resulting in two remarkable properties: 1) it does not require the relative rotation between targets and radar; 2) it can considerably avoid the image blurring in processing noncooperative targets without motion compensation. 3D radar coincidence imaging consequently can derive high-quality images for either the targets that are stationary with respect to radars or the ones in maneuvering 3D rotations. The validity of the proposed imaging technique is confirmed by numerical simulations.

A New Rang-Instantaneous Doppler ISAR Imaging Algorithm

ISAR imaging algorithm based on sparse representation has the advantages of high resolution, noise suppression and dealing with gapped data effectively. The method is based on the hypothesis that the imaging targets move smoothly. But the movement of ISAR imaging targets is usually of high maneuverability, which results in big phase error after motion compensation. Using the traditional RD imaging algorithm and the imaging algorithm based on sparse representation will make the resultant image fuzzy, and can't even be identified. This paper introduces a new range- instantaneous Doppler imaging algorithm based on sparse representation and time-frequency transform, which can effectively image the maneuvering target. The experimental results validate the feasibility of this approach.

Development of instantaneous temperature imaging in sooty flames

Development of instantaneous temperature imaging in sooty flames

Peripheral and Central Bone Mineral Density in Charcot’s Neuroarthropathy Compared in Diabetic and Nondiabetic Populations

This prospective study was performed to compare calcaneal and lumbar bone mineral density (BMD) in individuals with and without diabetes mellitus. We compared bone density with the time from onset of Charcot's neuroarthropathy (CN) in patients with unilateral, nonoperative, reconstructive-stage CN. The final purpose was to investigate the role that sex, age, and serum vitamin D level may have in osseous recovery. Thirty-three individuals were divided into three groups: controls and patients with diabetes mellitus with and without CN. Peripheral instantaneous x-ray imaging and dual-energy x-ray absorptiometry were performed. The calcaneal BMD of patients with diabetes mellitus and CN was lower than that of the control group (P < .01) but was not significantly lower than that of patients with diabetes mellitus alone. There was no statistically significant difference in lumbar T-scores between groups. Women demonstrated lower BMD than did men (P = .02), but patients 60 years and older did not demonstrate significantly lower BMD than did patients younger than 60 years (P = .135). A negative linear relationship was demonstrated between time and BMD in patients with CN. The results of this study suggest that lumbar BMD does not reflect peripheral BMD in patients with diabetes mellitus and reconstructive-stage CN. This study has clinical implications when reconstructive osseous surgery is planned in patients with CN.

Comparative evaluation of the image-reconstruction algorithms of single-shot phase-shifting digital holography

We comparatively evaluated two types of image-reconstruction algorithms in two types of single-shot phase-shifting digital holography techniques to investigate which algorithm is more suitable for high-quality and instantaneous three-dimensional imaging. Two types of image-reconstruction algorithms were proposed for each single-shot phase-shifting interferometry so far. One generates multiple phase-shifted holograms from the recorded single hologram by utilizing interpolation and derives the complex amplitude of the object wave by applying the calculation of phase-shifting interferometry to the multiple phase-shifted holograms. The other does not use interpolation but applies the calculation of phase-shifting interferometry to the neighboring pixels in the recorded hologram to derive the complex amplitude. We experimentally evaluated the qualities of the image reconstructed by the algorithms in each single-shot phase-shifting technique. It was clarified that the former algorithm is more effective for high-quality imaging free from the unwanted images in single-shot technique using an array of optical elements. In single-shot technique using spatial carrier, although the latter algorithm is able to reconstruct a brighter image for wide area than the former, spatial-filtering technique is needed for removing the conjugate image.

Time distribution characteristics of cat-eye reflected light from moving optical target

By using the Collins diffraction formula and expanding the aperture function into a finite sum of complex Gaussian functions, an analytical formula of the time light intensity distribution for oblique Gaussian beams passing through a moving cat-eye optical lens and going back along the entrance way is deduced. By numerical computation, the variation laws of the time intensity distributions of the cat-eye reflected light with the viewing angle, imaging distance, aperture and instantaneous field of view are given. The results show that the relationship between the light intensity at the return place and the detection time is linear, and it is of inverse proportion only when the viewing angle is very large. For the staring imaging optical lens, the nonlinear extent of the time distribution curve becomes larger with the decrease of the viewing angle. For the instantaneous imaging optical lens, there is still some cat-eye reflected light when the detection system is out of the viewing field of the target lens.

Effects of motion on optical properties in the spatial frequency domain

Spatial frequency domain imaging (SFDI) is a noncontact and wide-field optical imaging technology currently being used to study the optical properties and chromophore concentrations of in vivo skin including skin lesions of various types. Part of the challenge of developing a clinically deployable SFDI system is related to the development of effective motion compensation strategies, which in turn, is critical for recording high fidelity optical properties. Here we present a two-part strategy for SFDI motion correction. After verifying the effectiveness of the motion correction algorithm on tissue-simulating phantoms, a set of skin-imaging data was collected in order to test the performance of the correction technique under real clinical conditions. Optical properties were obtained with and without the use of the motion correction technique. The results indicate that the algorithm presented here can be used to render optical properties in moving skin surfaces with fidelities within 1.5% of an ideal stationary case and with up to 92.63% less variance. Systematic characterization of the impact of motion variables on clinical SFDI measurements reveals that until SFDI instrumentation is developed to the point of instantaneous imaging, motion compensation is necessary for the accurate localization and quantification of heterogeneities in a clinical setting.

Valve anatomy and function with transthoracic three-dimensional echocardiography: advantages and limitations of instantaneous full-volume color Doppler imaging

Three-dimensional echocardiography (3DE) is becoming part of everyday clinical practice worldwide. However, 3DE requires adequate electrocardiographic and respiratory gating and it complements instead of replacing bidimensional echocardiography (2D). The instantaneous full-volume echocardiography technique is trying to overcome some of these limitations and to present an effective alternative to 2D echocardiography. In this article we aim to review the contribution of 3DE to our knowledge of anatomic and functional valvular anatomy and the potential advantages of instantaneous full-volume color Doppler echocardiography.

Confocal laser endomicroscopy for the diagnosis of urothelial bladder neoplasia: a technology of the future?

To evaluate bladder urothelium by confocal laser endomicroscopy (CLE) and correlate microscopic findings with standard histopathology. Fresh bladder urothelium tissue specimens were topically stained with acriflavine for instantaneous microscopic imaging. A single-line laser in a handheld CLE probe delivered an excitation wavelength of 488 nm providing a high resolution of 0.7 µm and an adjustable imaging depth of 0-250 µm. Resection specimens of 18 patients were investigated with 1000-fold magnification and ex vivo findings were compared with targeted histopathology (haematoxylin and eosin staining). Typical tumour growth patterns such as altered nuclear to cytoplasmic ratio, pseudopapillar tissue stratification and neoangiogenesis were readily visible. Nuclear and subnuclear architecture of healthy bladder tissue could be discriminated against neoplastic tissue. In addition to white light cystoscopy, CLE is a promising novel tool for the in vivo microscopic visualization of bladder cancer; first results of the present study show its potential to define microscopic characteristics of bladder cancer tissue. Further in vivo studies are necessary to determine sensitivity and specificity of the technique.

Confocal Laser Endomicroscopy: Technical Advances and Clinical Applications

Since its introduction in 2004, confocal laser endomicroscopy (CLE) has emerged as a valuable tool for gastrointestinal endoscopic imaging. Endomicroscopy enables the endoscopist to obtain real time in vivo histology during ongoing endoscopy thereby creating “optical biopsies.” To date, numerous studies have shown potential applications of endomicroscopy in the clinical setting, including in vivo diagnosis of esophageal squamous cell carcinoma, Barrett’s esophagus, celiac disease, and colonic polyps. Moreover, recent data suggest the potential application of endomicroscopy in the field of molecular imaging. Additionally, in recent months new applications and developments in the field of confocal imaging were introduced including endomicroscopy of the liver, pancreatic, and bile ducts. Furthermore, by introducing a new needle-based confocal imaging system, which is small enough to be introduced through a 22gauge puncture needle, a wide field for new applications of endomicroscopic imaging has been opened. Currently, 2 CE- and US Food and Drug Administration (FDA)approved devices for endomicroscopy are available (Figures 1 and 2; Supplementary Table 1). In this review, we introduce both systems and discuss new technical advances and clinical applications of CLE.

Missile target automatic recognition from its decoys based on image time-series

As the development of the technology for radar target recognition, missile target automatic recognition has received considerable attention in recent years. Missile target, compared with the plane target, is hard to recognize for its smallness, feebleness and maneuver. In this paper, a new recognition method based on radar image time-series, which can significantly reduce the recognition time and classification error, is proposed. The image time-series are produced by range instantaneous Doppler imaging algorithm firstly, and then cross-range scaling of the images is processed. In particular, the inertia ratio, extracted from the obtained image time-series, is introduced to distinguish the missile from decoys. Furthermore, the effectiveness of this method is demonstrated by application to simulated data and it has been shown that this method has the potential to be used in a number of real-time applications.

3D photogrammetric analysis of the load-bearing foot

Surpisingly, little is know about how the foot carries load while walking. Motion of the bones or shape of the foot during load-bearing has been studied using video fluoroscopy, laser scanning phtogrammetry or modelled from static poses using finite element techniques. Also, pressure under the foot is regularly measured, but how the plantar surface changes during weight-bearing is unknown despite being relevant to shoe design and orthothic prescriiption for the normal and pathological foot. Close-range photogrammetry (CRP) has been used extensively in medical applications, such as craniofacial mapping and scoliosis screening to obtain three-dimensional data and provides a feasible method for measuring the plantar surface of the foot during gait. Advantages of this method over existing imaging techniques are that it is (i) non-contact and non-invasive, (ii) provides instantaneous imaging, (iii) is highly accurate, and (iv) allows for dynamic analysis of structures. This paper presents the development and application of a novel CRP technique for studying 3D shape of the plantar surfuace of the foot during gait.

Sensitivity Analysis of Multichannel Images Intended for Instantaneous Imaging Spectrometry Applications

This paper presents a sensitivity analysis of using instantaneous multichannel two-dimensional (2D) imaging to achieve instantaneous 2D imaging spectroscopy. A simulated multiple-filter mosaic was introduced and used to acquire multichannel data which were transformed into spectra. The feasibility of two different transformation approaches (the concrete pseudoinverse approach and a statistical approach) was investigated through extensive experimental tasks. A promising statistical method was identified to be used for accurate estimation of spectra from multichannel data. Comparison between estimated and measured spectra shows that higher estimation accuracy can be achieved when using a larger number of usable multiple-filter combinations in the mosaic.

逆合成孔径成像激光雷达数据采样技术

Inverse Synthetic Aperture Imaging LADAR can realize the instantaneous high-resolution imaging for moving target.Howerver,the ultra-wide bandwidth of the laser signal and the weakness of the echo signal brings some difficulties in the signal sampling.A method which combines the optical heterodyne detection technique and compressed sensing theory is proposed to solve this problem.The optical heterodyne detection technique is utilized to reduce the bandwidth of echo signal,then the compressed sensing theory is developed to realize sampling and reconstruction of the signal.Simulations demonstrate that high-quality images can be reconstructed even though the sampling rate is much lower than the Nyquist rate.

Low-frequency target strength and abundance of shoaling Atlantic herring (Clupea harengus) in the Gulf of Maine during the Ocean Acoustic Waveguide Remote Sensing 2006 Experiment

The low-frequency target strength of shoaling Atlantic herring (Clupea harengus) in the Gulf of Maine during Autumn 2006 spawning season is estimated from experimental data acquired simultaneously at multiple frequencies in the 300-1200 Hz range using (1) a low-frequency ocean acoustic waveguide remote sensing (OAWRS) system, (2) areal population density calibration with several conventional fish finding sonar (CFFS) systems, and (3) low-frequency transmission loss measurements. The OAWRS system's instantaneous imaging diameter of 100 km and regular updating enabled unaliased monitoring of fish populations over ecosystem scales including shoals of Atlantic herring containing hundreds of millions of individuals, as confirmed by concurrent trawl and CFFS sampling. High spatial-temporal coregistration was found between herring shoals imaged by OAWRS and concurrent CFFS line-transects, which also provided fish depth distributions. The mean scattering cross-section of an individual shoaling herring is found to consistently exhibit a strong, roughly 20 dB/octave roll-off with decreasing frequency in the range of the OAWRS survey over all days of the roughly 2-week experiment, consistent with the steep roll-offs expected for sub-resonance scattering from fish with air-filled swimbladders.

In Vivo Molecular Imaging of Colorectal Cancer With Confocal Endomicroscopy by Targeting Epidermal Growth Factor Receptor

Epidermal growth factor receptor (EGFR) is a therapeutic target for colorectal cancer (CRC). However, technical challenges have limited in vivo imaging of EGFR in CRCs. Confocal laser endomicroscopy (CLE) enables accurate microscopic visualization of CRC in patients during endoscopy. We evaluated the ability to use CLE in vivo for instantaneous molecular imaging of EGFR in CRC models. Tumors were grown in mice (n = 68) from human CRC cell lines that expressed high (SW480 cells) or low (SW620 cells) levels of EGFR. Tumors were visualized in vivo with a handheld CLE probe after injection of fluorescently labeled EGFR antibodies. EGFR-specific fluorescence was graded from 0 to 3+. Neoplastic and non-neoplastic specimens from human colorectal mucosa were examined. In vivo findings were correlated with histopathology, immunohistochemistry, and fluorescence microscopy analyses. CLE analysis of cell cultures confirmed the different expression levels of EGFR between cell lines. In living animals, CLE differentiated EGFR expression levels between tumor cell limes (mean fluorescence, 1.92 +/- 0.22 [SW480] and 0.59 +/- 0.21 [SW620], P = .0004). CLE analysis of EGFR expression in human specimens allowed distinction of neoplastic from non-neoplastic tissues (mean fluorescence, 2.0 +/- 0.37 vs 0.25 +/- 0.16, respectively, P = .0035). CLE can be used for in vivo, molecular analysis of CRC and to differentiate EGFR expression patterns in xenograft tumors and human tissue samples. Because CLE can be performed during endoscopy, in vivo molecular imaging might be used in diagnosis of CRC and to predict response to targeted therapies.