Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “CCD”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

High-resolution CCD imagers using area-array CCD's for sensing spectral components of an optical line image

CCD imagers with a novel replicated-line-imager architecture are abutted to form an extended line sensor. The sensor is preceded by optics having a slit aperture and having an optical beam splitter or astigmatic lens for projecting multiple line images through an optical color-discriminating stripe filter to the CCD imagers. A very high resolution camera suitable for use in a satellite, for example, is thus provided. The replicated-line architecture of the imager comprises an area-array CCD, successive rows of which are illuminated by replications of the same line segment, as transmitted by respective color filter stripes. The charge packets formed by accumulation of photoresponsive charge in the area-array CCD are read out row by row. Each successive row of charge packets is then converted from parallel to serial format in a CCD line register and its amplitude sensed to generate a line of output signal.

Elabd, Hammam↗
NASA NTRS1975

Development of a CCD for ultraviolet imaging using a CCD photocathode combination

CCD in the electron-in mode, coupled with a bi-alkali photocathode to produce UV photon conversion, provides the following desirable features: (1) high UV response of the bi-alkali photocathode; (2) excellent imaging quality of a CCD area array; and (3) high signal-to-noise ratio due to the EBS (electron bombarded silicon) gain of the CCD operating in a tube configuration. This paper describes the rationale and progress made in developing a CCD for use as an UV imager.

Collins, D. R.↗
NASA NTRS1989

A programmable CCD driver circuit for multiphase CCD operation

A programmable CCD (charge-coupled device) driver circuit was designed to drive CCDs in multiphased modes. The purpose of the drive electronics is to operate developmental CCD imaging arrays for NASA's tiltable moderate resolution imaging spectrometer (MODIS-T). Five objectives for the driver were considered during its design: (1) the circuit drives CCD electrode voltages between 0 V and +30 V to produce reasonable potential wells, (2) the driving sequence is started with one input signal, (3) the driving sequence is started with one input signal, (4) the circuit allows programming of frame sequences required by arrays of any size, (5) it produces interfacing signals for the CCD and the DTF (detector test facility). Simulation of the driver verified its function with the master clock running up to 10 MHz. This suggests a maximum rate of 400,000 pixels/s. Timing and packaging parameters were verified. The design uses 54 TTL (transistor-transistor logic) chips. Two versions of hardware were fabricated: wirewrap and printed circuit board. Both were verified functionally with a logic analyzer.

Ewin, Audrey J.↗
NASA NTRS1986

CCD imager with photodetector bias introduced via the CCD register

An infrared charge-coupled-device (IR-CCD) imager uses an array of Schottky-barrier diodes (SBD's) as photosensing elements and uses a charge-coupled-device (CCD) for arranging charge samples supplied in parallel from the array of SBD's into a succession of serially supplied output signal samples. Its sensitivity to infrared (IR) is improved by placing bias charges on the Schottky barrier diodes. Bias charges are transported to the Schottky barrier diodes by a CCD also used for charge sample read-out.

Kosonocky, Walter F.↗
NASA NTRS1992

CCD data acquisition systems at Lick and Keck Observatories

This paper will describe and compare two distinct but related CCD data acquisition systems (DAS) currently under development at Lick and Keck Observatories. Although these two systems have a number of major architectural differences, they share a considerable amount of common hardware and software. Both of these new systems build on a large body of proven software that is the foundation of the existing CCD DAS currently in use at Lick Observatory. Both will provide support for reading up to four on-chip amplifiers per CCD and/or reading out mosaics of CCD chips. In addition, they will provide the capability for interactive, real-time adjustment of CCD waveforms for engineering purposes. Each of these two systems is composed of three major subsystems: (1) an instrument computer and its software; (2) a data capture computer and its software; and (3) a CCD/dewar controller and its software. The instrument computer is a Unix workstation, and the functions it provides include user interfaces, the interactive real-time display of CCD images, and the recording of image and FITS header data to disk and/or tape. The data capture computer is responsible for the packaging and high-speed transfer of the CCD pixel data stream into a bulk RAM, and the subsequent transfer of this data to the instrument computer. The CCD/dewar controller generates the waveforms for clocking the CCD, digitizes the pixel data, and transmits it via high-speed link to the data capture computer. It is also responsible for monitoring and controlling the dewar temperature and cryogen levels. Given the number of different types of processors and high-speed data links employed in both systems, a major emphasis of this paper will be on the various forms of interprocessor communications utilized for data transfer and distributed process synchronization.

Kibrick, R. I.↗
NASA NTRS1979

Large area CCD image sensors for space astronomy

The Defense Advanced Research Projects Agency (DARPA) has a substantial program to develop a 2200 x 2200 pixel CCD (Charge Coupled Device) mosaic array made up of 400 individual CCD's, 110 x 110 pixels square. This type of image sensor appeared to have application in space and ground-based astronomy. Under this grant a CCD television camera system was built which was capable of operating an array of 4 CCD's to explore the suitability of the CCD's to explore the suitability of the CCD for astronomical applications. Two individual packaged CCD's were received and evaluated. Evaluation of the basic characteristics of the best individual chips was encouraging, but the manufacturer found that their yield in manufacturing this design is two low to supply sufficient CDD's for the DARPA mosaic array. The potential utility of large mosaic arrays in astronomy is still substantial and continued monitoring of the manufacturers progress in the coming year is recommended.

Schwarzschild, M.↗
NASA NTRS1981

CCD correlated quadruple sampling processor

A correlated quadruple sampling processor for improved signal-to-noise ratio in the output of a charge-coupled device (CCD) is comprised of: switching means for momentarily clamping a CCD signal line at a first reference level A before a CCD data pulse and then obtaining a first data sample B with respect to the reference A during a CCD data pulse, and storing the positive sample B-A; switching means for momentarily clamping the CCD signal line a second time at the level C during the presence of the CCD data pulse and then obtaining a second data sample D with respect to the reference level C after the CCD data pulse, and storing the negative sample D-C; and means for obtaining the difference between the stored samples +(B-A) and -(D-C), thus increasing the net signal amplitude by a factor of about 2 while the noise would be increased by only a factor of square root of 2 since there will be no correlation in the noise between the double samples +(B-A) and -(D-C) effectively added.

Gaalema, S. D.↗
NASA NTRS1989

CCD TV focal plane guider development and comparison to SIRTF applications

It is expected that the SIRTF payload will use a CCD TV focal plane fine guidance sensor to provide acquisition of sources and tracking stability of the telescope. Work has been done to develop CCD TV cameras and guiders at Lick Observatory for several years and have produced state of the art CCD TV systems for internal use. NASA decided to provide additional support so that the limits of this technology could be established and a comparison between SIRTF requirements and practical systems could be put on a more quantitative basis. The results of work carried out at Lick Observatory which was designed to characterize present CCD autoguiding technology and relate it to SIRTF applications is presented. Two different design types of CCD cameras were constructed using virtual phase and burred channel CCD sensors. A simple autoguider was built and used on the KAO, Mt. Lemon and Mt. Hamilton telescopes. A video image processing system was also constructed in order to characterize the performance of the auto guider and CCD cameras.

Rank, David M.↗
NASA NTRS1992

Mosaic CCD method: A new technique for observing dynamics of cometary magnetospheres

On April 29, 1990, the plasma tail of Comet Austin was observed with a CCD camera on the 105-cm Schmidt telescope at the Kiso Observatory of the University of Tokyo. The area of the CCD used in this observation is only about 1 sq cm. When this CCD is used on the 105-cm Schmidt telescope at the Kiso Observatory, the area corresponds to a narrow square view of 12 ft x 12 ft. By comparison with the photograph of Comet Austin taken by Numazawa (personal communication) on the same night, we see that only a small part of the plasma tail can be photographed at one time with the CCD. However, by shifting the view on the CCD after each exposure, we succeeded in imaging the entire length of the cometary magnetosphere of 1.6 x 10(exp 6) km. This new technique is called 'the mosaic CCD method'. In order to study the dynamics of cometary plasma tails, seven frames of the comet from the head to the tail region were twice imaged with the mosaic CCD method and two sets of images were obtained. Six microstructures, including arcade structures, were identified in both the images. Sketches of the plasma tail including microstructures are included.

Saito, T.↗
NASA NTRS1991

Calibration Tests of Industrial and Scientific CCD Cameras

Small format, medium resolution CCD cameras are at present widely used for industrial metrology applications. Large format, high resolution CCD cameras are primarily in use for scientific applications, but in due course should increase both the range of applications and the object space accuracy achievable by close range measurement. Slow scan, cooled scientific CCD cameras provide the additional benefit of additional quantisation levels which enables improved radiometric resolution. The calibration of all types of CCD cameras is necessary in order to characterize the geometry of the sensors and lenses. A number of different types of CCD cameras have been calibrated a the NASA Langley Research Center using self calibration and a small test object. The results of these calibration tests will be described, with particular emphasis on the differences between standard CCD video cameras and scientific slow scan CCD cameras.

Shortis, M. R.↗
NASA NTRS1984

Experience with 800 x 800 virtual phase and 500 x 500 three-phase CCD imagers

A description of the Galileo/Institute for Astronomy charge-coupled device (CCD) imaging system and its initial operation has been presented previously. Originally designed to operate a 500 x 500 backside illuminated three-phase CCD, the system has been modified to allow use of either the 500 x 500 sensor or the TI 800 x 800 virtual phase CCD. The modifications for the operation of the virtual phase CCD and current system performance with each type of sensor are discussed. A description is given of the implementation of various techniques discovered at the Jet Propulsion Laboratory that improve imager performance. These techniques include tri-level clocking of the virtual phase CCD to eliminate spurious charge generation in the serial register, the use of ultraviolet light flood with the backside thinned 500 x 500 three-phase device to dramatically improve the quantum efficiency in the blue, and the practical elimination of deferred charge in the three-phase device. Results of astronomical observations with each sensor are presented.

Hlivak, R. J.↗
NASA NTRS1988

CCD camera system for cometary research

The objective is to upgrade the NASA/GSFC 36 inch telescope instrumentation, primarily with a new charge coupled device (CCD) camera system, to permit an effective monitoring program of cometary activity by means of narrowband imaging and spectroscopic techniques. Researchers have twice taken delivery of the CCD camera system from Princeton Scientific Instruments and twice returned it within six weeks for repair. During the times they had the camera system in the lab, they measured the instrumental performance of the TEK 512 x 512 CCD chip (e.g., readout noise, dark current, etc) and developed the complete operational software for the camera system plus several useful observing and data reduction routines for use at the telescope. The CCD camera system is controlled by an IBM-AT computer. The peripheral equipment and software to permit the efficient transfer of large amounts of data to the LASP's computers (VAXs) and subsequent timely reductions are also in place. The Io torus (S II) emission was monitored with a Fabry-Perot scanning spectrometer, in conjunction with the International Jupiter Watch. The CCD camera system will be coupled to a narrowband interference filter imager and a long-slit spectrograph to provide regular and well-calibrated spatial and spectral observations of comets.

Oliversen, R. J.↗
NASA NTRS1990

A laboratory measurement of CCD photometric and dimensional stability

The sun exhibits periodic and quasi-periodic variability in its total luminosity, which provides information about its internal structure and dynamics. Variability ranges from a few minutes to many-year time scales, with amplitudes as small as a few ppm in the milliHz band. Extension of this analysis to a large sample of outer stars would be interesting: a panoramic detector such as a CCD could record many stars at once. To meet this objective, a ppm time-series differential precision is required. Laboratory CCD photometric measurements presented here are promising for such an instrument. Normalizing the response from a portion of the CCD area removes most of the individual-frame variability. When a trend attributed to a thermal transient in the CCD dewar is removed, the individual-frame photometric precision is about 0.0001, limited by photoelectron counting statistics. The time-series power spectrum is flat within the desired frequency domain. Analysis of the dimensional stability of the CCD within the same data set indicates better than ppm performance, when first-order bulk motion and magnification changes are removed.

Buffington, Andrew↗
NASA NTRS1992

Astronomical CCD observing and reduction techniques

CCD instrumentation and techniques in observational astronomy are surveyed. The general topics addressed include: history of large array scientific CCD imagers; noise sources and reduction processes; basic photometry techniques; introduction to differential time-series astronomical photometry using CCDs; 2D imagery; point source spectroscopy; extended object spectrophotometry; introduction to CCD astrometry; solar system applications for CCDs; CCD data; observing with infrared arrays; image processing, data analysis software, and computer systems for CCD data reduction and analysis. (No individual items are abstracted in this volume)

Howell, Steve B.↗
NASA NTRS1994

Versatile Controller For CCD's

General-purpose controller for charge-coupled device (CCD) programmed to accommodate variety of CCD designs. In operation of controller, software used to specify CCD-clock waveforms, available in great diversity. Includes timing-signal generator controlled by microcomputer. Flexibility and speed makes it versatile tool for laboratory testing and for variety of applications. Controller operates existing CCD's and able to operate CCD's expected to be developed in foreseeable future.

Novello, J.↗
NASA NTRS1992

The University of Hawaii Institute for Astronomy CCD camera control system

The University of Hawaii Institute for Astronomy CCD Camera Control System consists of a NeXT workstation, a graphical user interface, and a fiber optics communications interface which is connected to a San Diego State University CCD controller. The UH system employs the NeXT-resident Motorola DSP 56001 as a real time hardware controller. The DSP 56001 is interfaced to the Mach-based UNIX of the NeXT workstation by DMA and multithreading. Since the SDSU controller also uses the DPS 56001, the NeXT is used as a development platform for the embedded control software. The fiber optic interface links the two DSP 56001's through their Synchronous Serial Interfaces. The user interface is based on the NeXTStep windowing system. It is easy to use and features real-time display of image data and control over all camera functions. Both Loral and Tektronix 2048 x 2048 CCD's have been driven at full readout speeds, and the system is intended to be capable of simultaneous readout of four such CCD's. The total hardware package is compact enough to be quite portable and has been used on five different telescopes on Mauna Kea. The complete CCD control system can be assembled for a very low cost. The hardware and software of the control system has proven to be quite reliable, well adapted to the needs of astronomers, and extensible to increasingly complicated control requirements.

Jim, K. T. C.↗
NASA NTRS1992

Wilbur: A low-cost CCD camera system for MDM Observatory

The recent availability of several 'off-the-shelf' components, particularly CCD control electronics from SDSU, has made it possible to put together a flexible CCD camera system at relatively low cost and effort. The authors describe Wilbur, a complete CCD camera system constructed for the Michigan-Dartmouth-MIT Observatory. The hardware consists of a Loral 2048(exp 2) CCD controlled by the SDSU electronics, an existing dewar design modified for use at MDM, a Sun Sparcstation 2 with a commercial high-speed parallel controller, and a simple custom interface between the controller and the SDSU electronics. The camera is controlled from the Sparcstation by software that provides low-level I/O in real time, collection of additional information from the telescope, and a simple command interface for use by an observer. Readout of the 2048(exp 2) array is complete in under two minutes at 5 e(sup -) read noise, and readout time can be decreased at the cost of increased noise. The system can be easily expanded to handle multiple CCD's/multiple readouts, and can control other dewars/CCD's using the same host software.

Metzger, M. R.↗
NASA NTRS2001

Using a delta-doped CCD to determine the energy of a low-energy particle

The back surface of a thinned charged-coupled device (CCD) is treated to eliminate the backside potential well that appears in a conventional thinned CCD during backside illumination. The backside of the CCD includes a delta layer of high-concentration dopant confined to less than one monolayer of the crystal semiconductor. The thinned, delta-doped CCD is used to determine the energy of a very low-energy particle that penetrates less than 1.0 nm into the CCD, such as a proton having energy less than 10 keV.

Nikzad, Shouleh↗