Optoelectronic Imaging System Research Articles

Research progress of laser protection technology for optoelectronic imaging system (invited)

Research progress of laser protection technology for optoelectronic imaging system (invited)

A diamond voltage imaging microscope

Technologies that capture the complex electrical dynamics occurring in biological systems, across fluid membranes and at solid–liquid interfaces are important for furthering fundamental understanding and innovation in diverse fields from neuroscience to energy storage. However, the capabilities of existing voltage imaging techniques utilizing microelectrode arrays, scanning probes or optical fluorescence methods are limited by resolution, scan speed and photostability, respectively. Here we report an optoelectronic voltage imaging system that overcomes these limitations by using nitrogen-vacancy defects as charge-sensitive fluorescent reporters embedded within a transparent semiconducting diamond device. Electrochemical tuning of the diamond surface termination enables photostable optical voltage imaging with a quantitative linear response at biologically relevant voltages and timescales. This technology represents a major step towards label-free, large-scale and long-term voltage recording of physical and biological systems with sub-micrometre spatial resolution.

Extraction of Trap Energy Distribution in Proton-Irradiated Focal Plane Arrays Using a High-Precision Random Telegraph Noise Detection Algorithm

Random telegraph noise (RTN) is a type of low-frequency noise that degrades the sensitivity of focal plane arrays (FPAs) and other electronics. Careful analysis of RTN provides information about the material defects generating this noise and ultimately may lead to a solution to eliminate this noise source from the optoelectronic imaging system. The focus of this effort is the definition and demonstration of a simple histogram-based detection algorithm, which evaluates the shape of the pixel output histogram in order to detect RTN pixels and extract the energy levels of the defects. The algorithm sensitivity and precision statistics are benchmarked as a function of the detection threshold. Applying the algorithm to a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1280\times1024$ </tex-math></inline-formula> infrared FPA irradiated with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.2\times 10^{11}$ </tex-math></inline-formula> protons/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (63 MeV) shows a maximum 84% increase in the number of pixels exhibiting RTN from preradiation to post-300 K anneal. The distribution of preradiation trap energies shows clusters at 13 meV above the Fermi level and 14 and 44 meV below the Fermi level. The radiation-induced defects, however, exhibit a different energy distribution with an increased concentration at the Fermi level, suggesting different energy distributions for the traps created during the manufacturing process compared to those created by proton radiation.

Thermodynamic parameters of helium under shock-wave and quasi-isentropic compressions at pressures up to 4800 GPa and compression ratios up to 900

The thermodynamic parameters of a strongly nonideal helium plasma obtained in experimental devices of hemispherical and spherical geometries are presented. Under shock-wave loading in the hemispherical device, the helium plasma was compressed to a density ρ ≈ 0.76 g cm–3 by a pressure P ≈ 83 GPa at a temperature T ≈ 51000 K. Two-cascade spherical experimental devices of two types were used under quasi-isentropic helium plasma compression. In the devices of the first type at the same initial gas pressure in both cavities of the shells, the helium plasma was compressed approximately by a factor of 200 to a density ρ ≈ 8 g cm–3 by a pressure P ≈ 4800 GPa. In the devices of the second type at a ratio of the initial gas pressures in the cavities of about 9: 1, the thermodynamic parameters of a nonideal helium plasma compressed by a factor of 900 to a density ρ ≈ 5 g cm–3 by a pressure P ≈ 3700 GPa were determined. The compressed-plasma pressure was determined from the results of gasdynamic computations. An X-ray radiograph consisting of three betatrons and a multichannel optoelectronic X-ray imaging system was used to determine the positions of the boundaries of the gaseous-helium-compressing steel shell.

Spastic diparetic does not directly affect the capacity to ascend and descend access ramps: three-dimensional analysis

Abstract Introduction: Diplegic children have difficulties in gait and therefore ramps are used as strategies of accessibility. Objective: The present study investigated the influence of an inclined surface (ascending and descending) on the kinematic characteristics during gait of the diplegic group (DG) when compared to typically developing children of the control group (CG). Methods: Study participants included 20 children (10 with DG and 10 CG) matched by age, which were evaluated in three experimental conditions (horizontal and inclined ascending and inclined descending surfaces of 7º) through an optoelectronic imaging system. Results: Among the linear kinematic variables, only step width differed among groups, however, without influence of the surface. The foot height differed among the groups only in the descending phase, where DG had greater difficulty in raising the foot. The 3-dimensional gait analyses could not provide more evidences of differences in kinematics variables, especially in transverse plane, between DG and CG, but provide some evidence to support that hip range of motion (ROM) during the gait cycle, hip flexion-extension in initial contact, knee ROM and the 2nd anterior-posterior trunk peak amplitude of the DG were influenced on descent by their flexor pattern. Conclusion: The DG was most affected by the inclination plane than CG especially on descent. Although a hip and knee flexor pattern is evident for DG on inclination of 7º, this angle is accessible since it allows independent gait functional activity.

Design of Motion Control Card on PXI Bus

The article introduces the design scheme of a motion control card on PXI bus. A detailed description of PCI interface module, FPGA module, DSP module, serial transceiver module and analog acquisition module is also given in this paper. Tests of data transfer rate between host and motion control card are adopted, the results suggest that the PXI local bus can get a high-rate communication. The motion control card is applied to control the two-dimensional turntable of an optoelectronic imaging and tracking system. The experiments indicate that the motion control card based on PXI can meet the requirements of real-time control. The performance of control is also acceptable.

Color imaging with an integrated compound imaging system

Color-imaging methods with an integrated compound imaging system called TOMBO (Thin observation module by bound optics) are presented. The TOMBO is a compact optoelectronic imaging system for image capturing based on compound-eye imaging and post digital processing. First, a general description of the TOMBO system is given, and then two configurations for color imaging are described. Experimental comparison of these configurations is made by use of an experimental TOMBO system. The characteristics and the performance on the proposed methods are briefly discussed.

Trunk posture:: reliability, accuracy, and risk estimates for low back pain from a video based assessment method

It has been recently reported that both dynamic movement characteristics, as well as the duration of postures adopted during work, are important in the development of low back pain (LBP). This paper presents a video-based posture assessment method capable of measuring trunk angles and angular velocities in industrial workplaces. The inter-observer reliability, system accuracy, and the relationship of the measured exposures to the reporting of low back pain are reported. The video analysis workstation consisted of a desktop computer equipped with digital video capture and playback technology, a VCR, and a computer game type joystick. The operator could then use a joystick to track trunk flexion and lateral bending during computer-controlled video playback. The joystick buttons were used for binary input of twisting. The inter-observer reliability for peak flexion and percentage of time spent in posture category variables were excellent (ICC>0.8). Lower reliability levels were observed for peak and average velocity and movement related variables. The video analysis system time series data showed very high correlation to the criterion optoelectronic imaging system ( r=0.92). Root mean square errors averaged 5.8° for the amplitude probability distribution function data. Trunk flexion variables including peak level, peak velocity, average velocity indicators, and percent time in flexion category indicators all showed significant differences between cases and controls in the epidemiological study. A model consisting of the measures peak trunk flexion, percent time in lateral bend and average lateral bending velocity emerged after multivariable analysis for relationship to low back pain. Relevance to industry Risk of injury for the low back is multifactorial. The trunk position and movement velocity are emerging as important parameters. This analysis confirms the importance of these factors and demonstrates the utility of a video-based method to measure them in industrial settings.

Methods for the deconvolution of defocused-image pairs recorded separately on two CCD cameras: application to particle sizing

An optoelectronic in-line imaging system for particle sizing is described. The images are scanned by two CCD cameras viewing the same object field that is illuminated with two pulses. One of the cameras is double exposed and the other is activated only during the second pulse. Two successive analogical subtractions between the video output signals gives the sign of the transverse velocity vector. Out-of-focus images are deconvolved with the assumption of a Gaussian point-spread function (PSF) whose spatial parameter ς increases with the defocusing distance z. In the case of low particle density, an algorithm based on the exploitation of the power spectral density is used to estimate the particle diameter. This method can be applied to the case of fast-moving particles (e.g., v < 500 m/s). The accuracy of the size measurement is better than 10% in the diameter range 20-160 μm. The main result is that this accuracy is obtained with an amount of defocusing in the range [-2, 2] mm. Thus, the depth of field is significantly extended in comparison with a conventional microscopic imaging system.

An optoelectronic imaging system for particle characterization

An optoelectronic imaging system for particle characterization in gas turbines is described. This system includes two CCD cameras viewing the same object field. One of these cameras is double exposed and the second is only open during the second pulse. An analogical subtraction between the output signals of these cameras gives the sign of the transverse velocity vector. Out of focus images are deconvolved by assuming a Gaussian point spread function (PSF) whose spatial parameter sigma increases with the defocusing distance z. The sign ambiguity on z is removed by comparing the power spectrum of the two different defocused images. The amount of defocusing is deduced from the intensity distribution slopes. The measurement accuracy of the size d is better than 10% for d>or=10 mu m through a sample volume with a depth of 4 mm.