Browse Topic: Charge coupled devices
With speeds of over 1-million frames per second, high-speed imaging is an invaluable research tool capable of capturing the most fleeting events in scientific and engineering applications. Yet, achieving this speed comes with strings attached. Most high-speed cameras are designed to achieve a maximum gigapixel/second (Gpx/sec) throughput, offered in a trade-off of frame rate to resolution. For example, a 25 Gpx/sec camera reaches 25,700 frames per second (fps) at a resolution of 1280 × 800 pixels and can achieve a higher frame rate of 28,500 at a smaller resolution of 1280 × 720. Both combinations have almost the same throughput. Very high frame rates such as 1-million fps are accompanied by very small resolutions, making it more challenging to see the subject matter
In a state-of-the-art lean-burn spark ignition engine, a strong in-cylinder flow field with enhanced turbulence intensity is formed, and understanding the wall heat transfer mechanism of such a complex flow is required. The flow velocity and temperature profiles inside the wall boundary layer are strongly related to the heat transfer mechanism. In this study, two-dimensional three-component (2D3C) velocity distribution near the piston top surface was measured during the compression stroke in a strong tumble flow using a rapid compression and expansion machine (RCEM) and a stereoscopic micro-PIV system. The bore, stroke, compression ratio, and compression time were 75 mm, 128 mm, 15, and 30 ms (equivalent to 1000 rpm), respectively. A double-pulse Nd:YAG laser sheet was introduced from the intake side, and PIV images were captured near the piston surface around the TDC under motored conditions with a measurement region of 5.2 mm × 6.9 mm (1200 × 1600 pixel, 4.3 μm/pixel) using two CCD
The first sCMOS (scientific Complementary Metal Oxide Semiconductor) cameras were introduced some 10 years ago and are now the dominant sensor technology used in microscopy imaging cameras. In recent years, a new generation of sCMOS camera models based on back-illuminated sCMOS sensors has appeared. This new iteration of sCMOS camera technology promises even higher sensitivity than prior designs, and therefore may displace previous generations of front-illuminated sCMOS cameras and further push EMCCD (Electron Multiplying Charge Coupled Device) cameras to more niche applications
One of the most important safety issues for automotive engineering is to avoid any fire due to the ignition of flammable liquids, which may result from leaks. Fire risk is a combination of hot temperature, fast vaporisation and accumulation of vapor in a cavity. In IC engines, potentially flammable liquids are fuel and oil. To guarantee safety, flammable liquids must not come into contact with hot parts of the engine. Consequently, shields are designed to guide the flow path of possible leakages and to take any flammable liquid out of the hot areas. Simulation is a great help to optimize the shape of the shield by investigating a large number of possible leakages rapidly. Recent breakthroughs in numerical methods make it possible to apply simulations to industrial design concepts. The employed approach is based on the Lagrangian Smoothed Particle Hydrodynamics (SPH) method. The SPH method is an efficient method to capture the rivulets on highly complex geometries and thus determine the
This SAE Aerospace Recommended Practice (ARP) contains methods used to measure the optical performance of airborne electronic flat panel display (FPD) systems. The methods described are specific to the direct view, liquid crystal matrix (x-y addressable) display technology used on aircraft flight decks. The focus of this document is on active matrix, liquid crystal displays (LCD). The majority of the procedures can be applied to other display technologies, however, it is cautioned that some techniques need to be tailored to different display technologies. The document covers monochrome and color LCD operation in the transmissive mode within the visual spectrum (the wavelength range of 380 to 780 nm). These procedures are adaptable to reflective and transflective displays paying special attention to the source illumination geometry. Photometric and colorimetric measurement procedures for airborne direct view CRT (cathode ray tube) displays are found in ARP1782. Optical measurement
ARP5061A provides guidelines for optical performance testing of short haul fiber optic inter-connection systems used in aerospace vehicles. The focus of this document is to introduce the proper testing tools and establish common pre- and post-installation test methods and troubleshooting methodologies
This SAE Aerospace Standard (AS) standardizes inspection and test procedures, workmanship criteria, and minimum training and certification requirements to detect Suspect/Counterfeit (SC) Electrical, Electronic, and Electromechanical (EEE) parts. The requirements of this document apply once a decision is made to use parts with unknown chain of custody that do not have pedigree back to the original component manufacturer or have been acquired from a broker or independent distributor, or when there are other known risk elements that result in the User/Requester to have concerns about potential SC EEE parts. The tests specified by this standard may also detect occurrences of malicious tampering, although the current version of this standard is not designed specifically for this purpose. This standard ensures consistency across the supply chain for test techniques and requirements based on assessed risk associated with the application, component, supplier, and other relevant risk factors
This SAE Aerospace Standard (AS) standardizes inspection and test procedures, workmanship criteria, and minimum training and certification requirements to detect Suspect/Counterfeit (SC) Electrical, Electronic, and Electromechanical (EEE) parts. The requirements of this document apply once a decision is made to use parts with unknown chain of custody that do not have pedigree back to the original component manufacturer, or have been acquired from a broker or independent distributor, or when there are other known risk elements that result in the User/Requester to have concerns about potential SC EEE parts. The tests specified by this standard may also detect occurrences of malicious tampering, although the current version of this standard is not designed specifically for this purpose. This standard ensures consistency across the supply chain for test techniques and requirements based on assessed risk associated with the application, component, supplier, and other relevant risk factors
If a vehicle is left in a humid environment, the coefficient of friction between the brake pads and discs increases, generating a discomforting noise during braking called brake squeal. It is assumed that this increase in the coefficient of friction in a humid environment is the effect of moisture penetrating between the brake friction surfaces. Therefore, this paper analyzes the factors causing coefficient of friction variation with moisture between the friction surfaces by dynamic observation of these surfaces. The observation was achieved by changing the disc materials from cast iron to borosilicate glass. One side of the glass brake disc was pushed onto the brake pad and the sliding surface was observed from the opposite side by a charge coupled device (CCD) camera. First, a preliminary test was carried out in a dry state using two pad materials with different wear properties to select the appropriate pad for observing the friction surfaces. Then, the characteristics of coefficient
Many users of CCD sensors are asking about the advantages of the latest CMOS sensors, particularly if they have been using CCD-based cameras. The two sensor technologies, a comparison of the new CMOS sensors and existing CCD sensors, and tips for when it makes sense to select a new camera with CMOS sensors are provided in this article, as well as what to expect after integration
A paper describes a new technique designed to increase significantly the sensitivity for finding and tracking small, dim, and fast-moving near Earth asteroids (NEAs). The technique relies on a combined use of a novel data processing approach and a new generation of high-speed CCD cameras. These new cameras have very low readout noise (≈le–) and allow taking short exposures of moving objects at high frame rates, effectively “freezing” their motion on the CCD. A long-exposure image is synthetically created as if the telescope were tracking the object with a significantly higher SNR — an approach called “synthetic tracking.” By changing the shift/add vector, multiple dim objects moving in different directions can be detected in the same data set
Traditional methods of photometry rely on the use of a goniometer to rotate the test item around two axes at right angles. This method is satisfactory for most situations but has certain disadvantages: a Point-by-point measurements with a goniometer may be slow. With more advanced requirements, particularly for headlamps, where the entire beam pattern is of concern, isocandela measurements are becoming increasingly needed. Such testing can be very time consuming. b For production quality assurance, the speed of a goniometer may not allow testing to keep pace with the production line if a large quantity of lamps must be sampled. c High Intensity Discharge (HID) lamps are becoming commonly used. Such lamps are orientation sensitive, changing in both lumen output and intensity distribution when tilted. This can introduce significant inaccuracies in test results when testing is performed using a goniometer. There is a need for alternative test techniques which can achieve very high speed
This SAE Recommended Practice establishes the minimum interface compatibility requirements for electric vehicle (EV) inductively coupled charging for North America. This part of the specification is applicable to manually connected inductive charging for Levels 1 and 2 power transfer. Requirements for Level 3 compatibility are contained in Appendix B. Recommended software interface messaging requirements are contained in Appendix A. This type of inductively coupled charging is generally intended for transferring power at frequencies significantly higher than power line frequencies. This part of the specification is not applicable to inductive coupling schemes that employ automatic connection methods or that are intended for transferring power at power line frequencies
Imagine a CCD camera operating on a long exposure and seeing only 1 electron per pixel every 16 minutes. That equates to dark current of less than 0.000001 electrons/pixel/sec. Imagine the same camera delivering less than 1.75 electrons readout noise with minimal hot spots and blemishes while delivering a peak QE of 77%. To hit these specs it would need to be cooled significantly
Natural gas has been considered as one promising alternative fuel for internal combustion (IC) engines to meet strict engine emission regulations and reduce the dependence on petroleum oil. Although compressed natural gas (CNG) intake manifold injection has been successfully applied into spark ignition (SI) engines in the past decade, natural gas direct injection compression ignition (DICI) engine with new injection system is being pursued to improve engine performance. Gas jet behaves significantly different from liquid fuels, so the better understanding of the effects of gas jet on fuel distribution and mixing process is essential for combustion and emission optimization. The present work is aimed to gain further insight into the characteristics of low pressure gas jet. An experimental gas jet investigation has been successfully conducted using tracer-based planar laser-induced fluorescence (PLIF) technique. For safety reason, nitrogen (N₂) was instead of CNG in this study. Vapor
This SAE Recommended Practice covers a procedure for evaluating plastic and multiple-layer coatings exposed to gravelometer testing (as defined in SAE J400) with an optical imaging and analysis system. The intent of the procedure is to detect, count and characterize instances of damage in the coated surface that fracture the top coat layer or penetrate through multiple layers of the coating system. It may be possible to extend this methodology of coating damage evaluation to specimens that have undergone test procedures or exposures that produce similar, discrete damage sites in the coating system. If so applied, evaluation results must be interpreted with respect to the limitations and intent implied by the original evaluation procedure and its associated rating system, if applicable
This SAE Aerospace Recommended Practice (ARP) contains methods used to measure the optical performance of airborne electronic flat panel display (FPD) systems. The methods described are specific to the direct view, liquid crystal matrix (x-y addressable) display technology used on aircraft flight decks. The focus of this document is on active matrix, liquid crystal displays (LCD). The majority of the procedures can be applied to other display technologies, however, it is cautioned that some techniques need to be tailored to different display technologies. The document covers monochrome and color LCD operation in the transmissive mode within the visual spectrum (the wavelength range of 380 to 780 nm). These procedures are adaptable to reflective and transflective displays paying special attention to the source illumination geometry. Photometric and colorimetric measurement procedures for airborne direct view CRT (cathode ray tube) displays are found in SAE ARP1782. Optical measurement
A two-tracer planar laser-induced fluorescence (PLIF) diagnostic technique was developed and applied to visualize the in-cylinder evaporation and distribution of different volatility fuel components in an optical spray-guided spark-ignition direct-injection (SIDI) engine. An image doubling and filtering system was designed so that LIF signals from the two tracers could be effectively separated and recorded simultaneously with one intensified charge coupled device (ICCD) camera. Cycle-resolved measurements were performed in the optical engine operated under late injection mode at different intake temperatures and pressures to assess the significance of sequential evaporation. The results demonstrate that the evaporation process under current experimental conditions is diffusion-controlled and the effects of sequential evaporation are insignificant on fuel distribution stratification. An order-of-magnitude estimate based on a Peclet number analysis supports this finding
A proposed multiloop power supply would generate a potential as high as 1.25 kV with rise and fall times <100 μs. This power supply would, moreover, be programmable to generate output potentials from 20 to 1,250 V and would be capable of supplying a current of at least 300 μA at 1,250 V. This power supply is intended to be a means of electronic shuttering of a microchannel plate that would be used to intensify the output of a charge-coupled-device imager to obtain exposure times as short as 1 ms. The basic design of this power supply could also be adapted to other applications in which high voltages and high slew rates are needed. At the time of reporting the information for this article, there was no commercially available power supply capable of satisfying the stated combination of voltage, rise-time, and fall-time requirements
A method of noncontact, optical monitoring of the surface temperature of a tire has been devised to enable the use of local temperature rise as an indication of potential or impending failures. The method involves the use of temperature-sensitive paint (or filler): Temperature-sensitive luminescent dye molecules or other luminescent particles are incorporated into a thin, flexible material coating the tire surface of interest. (Alternatively, in principle, the luminescent material could be incorporated directly into the tire rubber, though this approach has not yet been tested.) The coated surface is illuminated with shorter-wavelength light to excite longer-wavelength luminescence, which is observed by use of a charge-coupled-device camera or a photodetector (see Figure 1
A prototype optoelectronic system measures the three dimensional relative coordinates of objects of interest or of targets affixed to objects of interest in a workspace. The system includes a charge-coupled-device video camera mounted in a known position and orientation in the workspace, a frame grabber, and a personal computer running image-data-processing software. Relative to conventional optical surveying equipment, this system can be built and operated at much lower cost; however, it is less accurate. It is also much easier to operate than are conventional instrumentation systems. In addition, there is no need to establish a coordinate system through cooperative action by a team of surveyors
A paper introduces the concept of a stellar gyroscope, currently at an early stage of development, for determining the attitude or spin axis, and spin rate of a spacecraft. Like star trackers, which are commercially available, a stellar gyroscope would capture and process images of stars to determine the orientation of a spacecraft in celestial coordinates. Star trackers utilize charge coupled devices as image detectors and are capable of tracking attitudes at spin rates of no more than a few degrees per second and update rates typically <5 Hz. In contrast, a stellar gyroscope would utilize an active pixel sensor as an image detector and would be capable of tracking attitude at a slew rate as high as 50°/s, with an update rate as high as 200 Hz. Moreover, a stellar gyroscope would be capable of measuring a slew rate up to 420°/s. Whereas a Sun sensor and a three-axis mechanical gyroscope are typically needed to complement a star tracker, a stellar gyroscope would function without them
A process for n-type (electron-donor) delta (d) doping has shown promise as a means of modifying back-illuminated image detectors made from n-doped high-purity silicon to enable them to detect high-energy photons (ultraviolet and x-rays) and low-energy charged particles (electrons and ions). This process is applicable to imaging detectors of several types, including charge-coupled devices, hybrid devices, and complementary metal oxide/semiconductor detector arrays
Precision X-Y stages were developed for integration into a new analytical measurement tool for use in the development of digital inks or other fluids to be jetted from ink jet print heads. The Drop Watcher III system provides repeatable and exact measurements of drop formation (e.g., distance and time from the start of the drop ejection), drop size, and flight characteristics of opaque or transparent fluid drops. In addition to X-Y stages, the system consists of a monochrome CCD camera with a zoom lens providing magnification from 0.75X to 4X. Magnification from 2.5X to 10X is achievable when using the high-magnification option, yielding fields of view from 640 µm to 2.56 mm
The beamviewer is an optical device designed to be attached to a charge-coupled-device (CCD) image detector for measuring the spatial distribution of intensity of a beam of light (the "beam profile ") at a designated plane intersecting the beam. The beamviewer-and-CCD combination is particularly well suited for measuring the radiant-power profile (for a steady beam) or the radiant-energy profile (for a pulsed beam) impinging on the input face or emerging from the output face of a bundle of optical fibers. The beamviewer-and-CCD combination could also be used as a general laboratory instrument for profiling light beams, including beams emerging through small holes and laser beams in free space
An improved process that includes a high-temperature bonding subprocess has been developed to enable the fabrication of robust, flat, silicon-based charge-coupled devices (CCDs) for imaging in ultraviolet (UV) light and/or for detecting low energy charged particles. The CCDs in question are devices on which CCD circuitry has already been formed and have been thinned for back-surface illumination. These CCDs may be delta doped, and aspects of this type of CCD have been described in several prior articles in NASA Tech Briefs. Unlike prior low-temperature bonding subprocesses based on the use of epoxies or waxes, the high-temperature bonding subprocess is compatible with the delta-doping process as well as with other CCD-fabrication processes
A charge-coupled-device (CCD) based high-speed imaging system, called a real-time, event-driven (RARE) camera, is undergoing development. This camera is capable of readout from multiple subwindows [also known as regions of interest (ROIs)] within the CCD field of view. Both the sizes and the locations of the ROIs can be controlled in real time and can be changed at the camera frame rate. The predecessor of this camera was described in "High-Frame-Rate CCD Camera Having Subwindow Capability"(NPO-30564) NASA Tech Briefs, Vol. 26, No. 12 (December 2002), page 26. The architecture of the prior camera requires tight coupling between camera control logic and an external host computer that provides commands for camera operation and processes pixels from the camera. This tight coupling limits the attainable frame rate and functionality of the camera
The simple addition of a charge-coupled-device (CCD) camera to a theodolite makes it safe to measure the pointing direction of a laser beam. The present state of the art requires this to be a custom addition because theodolites are manufactured without CCD cameras as standard or even optional equipment
An improved and expanded method of stereo imaging velocimetry (SIV) for diagnosing three-dimensional flows of gases, liquids, and other fluids involves the use of standard charge-coupled-device cameras positioned orthogonally to each other. In addition to providing a full-field, quantitative, three-dimensional map of any optically transparent flow seeded with tracer particles, this SIV method incorporates a camera-calibration technique, in which rotation and translation of camera lenses and optical distortion generated in the lenses are taken into account by use of an accurate two-dimensional-to-three-dimensional mapping function
Efforts are under way to develop back-surface-illuminated, thinned silicon charge-coupled devices (CCDs) with delta doping and integral optical filters to be used as image detectors in the ultraviolet wavelength range. The concept of delta doping of back-surface-illuminated, thinned silicon CCDs as part of an overall design to make CCDs sensitive to ultraviolet light is not new in itself. Delta-doped CCDs were invented at NASA's Jet Propulsion Laboratory in 1992, and it is well established that this process produces ultraviolet-sensitive CCDs with stable and uniform 100-percent internal quantum efficiency. The novelty lies in the proposed fabrication of such CCDs in which both delta doping and optical filter layers would be deposited as integral parts of unitary device structures
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