Image Dissector Research Articles

1548C27 - an interesting new cometary nebula

The object 1548C27, a faint cometary nebula of classical form, discovered by an examination of early Near Infrared Photographic Sky Survey (NIPSS) data (1979) is presented. Direct imaging and polarimetric, photometric, and spectroscopic observations are reported. Early survey test photographs show that the object lies at R.A. 19h40m48s, Decl. +23 deg 17 arcmin 09 arc sec (1950) in the Vulpecula constellation in the immediate vicinity of the complex H II region and galactic cluster NGC 6820/6823. From the photographs, the nebula was estimated to be 15 m visual and of color class one. The object was observed spectroscopically in the region 5700-6800 A using an Image Dissector Scanner with a 1.8 m reflector, and the spectral scan, obtained on November 4, 1978, is presented. New information on cometary nebulae may further illuminate the evolutionary importance of the objects.

The Use of a High Temperature Hollow Cathode Lamp for the Determination of Trace Elements in Steels, Nickel-Base Alloys, and Ferroalloys by Emission Spectrometry

A high temperature hollow cathode lamp from Applied Research Laboratories, Luton, was used for multielement determination of trace elements in steels, nickel-base alloys and ferroalloys. A 10-mg sample (chips) was placed inside a hollow graphite electrode in the lamp, which was filled with helium. It was possible to raise the power through the lamp linearly and automatically, so that the combined thermal and sputtering effect in the lamp atomized the different elements one after another according to their boiling points. This selective volatilization improved the precision and the limits of detection for the elements determined. Analysis results for Pb, Bi, Zn, Ag, Sb, and Ca in the concentration range 0.05 to 100 μg g−1 are discussed. Because of the effective atomization in the lamp, no matrix effects were observed for these elements. One of the main purposes of this investigation was to study the time dependence of the intensity for the different elements during the volatilization phase. This procedure gave very clean spectra. In this investigation a new computerized image dissector echelle spectrometer, was used as the registration system.

An All-Sky Imaging Photometer

A versatile optical instrument capable of all-sky auroral imaging at low light levels is described. The All-Sky Imaging Photometer uses as a detector an image dissector photomultiplier tube operating in a photon-counting mode. A miniprocessor interprets commands entered interactively by the operator through a terminal, and controls data acquisition and display. A motorized filter wheel holding up to six interference filters permits monitoring of auroral emis-sions at monochromatic wavelengths.

Nebuliser system for analysis of high salt content solutions with an inductively coupled plasma

A nebuliser system for analysis of high salt content steel samples using an inductively coupled plasma is described. Because of its design this nebuliser system is capable of continuous operation with solutions of up to 10% salt content without clogging. The fabrication of the nebuliser was effected in a new and simple way. The effects on line to background ratios for several element lines which increased in intensity with higher salt concentrations were studied. Comparisons were also made with a conventional nebuliser system; the new system gave higher line to background ratios for the same salt concentrations. Analytical results for various amounts of steels containing trace and normal contents of other elements are discussed. For trace contents the relative standard deviations of the determinations were improved when salt concentrations up to 10% were used. No memory effects were noticed and the nebuliser system had a rapid clean-out time. Analysis was carried out using a computerised image dissector echelle spectrometer.

A 'cluster' of quasi-stellar objects near M82

The discovery of a cluster of three quasars near the peculiar Irr/Sc galaxy M82 is reported. The three objects were detected by the grism technique to lie in a relatively compact group southeast of M82, with similar redshifts and emission line ratios. Image dissector scanner observations were performed to confirm the nature of the sources as quasars and the quasar redshifts of approximately 2. Consideration of the probability of the chance occurrence of three quasars at this redshift within an angular distance of less than 3.6 arcmin leads to the conclusion that the three quasars are physically associated with each other. If the redshifts of these objects are interpreted as cosmological, then they may make up a cluster of quasars of dimensions comparable to those of galactic clusters. If, on the other hand, the quasars are at the distance of M82, then the noncosmological process which produces their redshifts must be capable of producing them within a narrow range.

A FIBER-OPTICS DISSECTOR FOR SPECTROSCOPY OF NEBULOSITIES AROUND QUASARS AND SIMILAR OBJECTS

ABSTRACT It is noted that to extract optimally the available spectroscopic information in nebulosities of quasars, two-dimensional spatial resolution is required and that this can be conveniently achieved by an image dissector device using fiber optics. The prototype used in the test, which has more than 200 fibers of 100 micron diameter and 100 mm length, transforms a hexagonal field into a straight line which constitutes the entrance slit of the spectrograph. On the basis of comparisons with classical slit spectra of the same object, it is concluded that such devices, coupled to adequate spectrographs and detectors, could yield reliable data on the structure of quasars' nebulosities or other faint objects with moderate extent.

Photometric Characteristics of Image Dissector Tubes in Photon Counting Operation

Extensive studies on the photometric characteristics and the imaging capability of image dissector tubes, operated under a photon counting scheme in low light level image observation have been carried out. Anode pulse height distribution of the circular aperture (50 µm in diameter) type particularly, shows good agreement with Poisson statistics; its photon counting response as well as its signal-to-noise ratio is considerably better than that of the bigger aperture such the 200×1000 µm2 rectangular type. The spatial resolution is alterable by varying the sampling pixel density. It is, however, limited physically by the size and shape of the aperture. Patterns of various structures have been used in intensity resolution study. Luminous pattern in dark background is likely to give higher intensity resolution than that of dark pattern in luminous background. In general, both the spatial and intensity resolving power of the circular type (tiny aperture) are found to be practically appreciable.

Determination of size and position of fast moving gas bubbles in liquids by digital 3-D image processing of hologram reconstructions

An experimental setup for digital 3-D image processing from hologram reconstructions is described. The real image as obtained upon reconstruction of the hologram with its conjugated reference wave is scanned by a movable image dissector camera without imaging optics and serves as analog 3-D picture input storage to the computer. This scheme has been developed to analyze automatically fast moving bubble fields in liquids recorded by high speed holographic techniques. A computer code has been written combining standard methods like gradient filtering from the field of image processing with specially developed algorithms for speckle noise suppression to locate and count the bubbles in the image volume and to determine their morphological data.

The ionization structure of the ring nebula. I - Sulfur and argon

view Abstract Citations (72) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The ionization structure of the ring nebula. I. Sulfur and argon. Barker, T. Abstract Measurements of line intensities in the Ring Nebula have been made in four of the six positions observed by Hawley and Miller over a wider wavelength range. The conclusions of Hawley and Miller about the physical conditions and ionization of He, O, Ne, and N are generally confirmed. New observations of S and Ar line intensities have been made, and new ionization correction formulae for these elements are examined. Publication: The Astrophysical Journal Pub Date: August 1980 DOI: 10.1086/158210 Bibcode: 1980ApJ...240...99B Keywords: Argon; Gas Ionization; Line Spectra; Planetary Nebulae; Spectral Energy Distribution; Sulfur; Abundance; Gas Density; Gas Temperature; Image Dissector Tubes; Stellar Mass; Tables (Data); Telescopes; Wavelengths; Astrophysics full text sources ADS | data products SIMBAD (2) Related Materials (16) Part 2: 1982ApJ...253..167B Part 3: 1982ispn.rept.....B Part 4: 1983ApJ...267..630B Part 5: 1983ispn.rept.....B Part 6: 1984ApJ...284..589B Part 7: 1985ispn.rept.....B Part 8: 1985ApJ...294..193B Part 9: 1986ApJ...308..314B Part 10: 1986STIN...8717582B Part 11: 1987ApJ...322..922B Part 12: 1987ispn.rept.....B Part 13: 1988ApJ...326..164B Part 14: 1988ispn.rept.....B Part 15: 1989ApJ...340..921B Part 16: 1989STIN...9029274B Part 17: 1991ApJ...371..217B

The use of the Kitt Peak IDS in determining galaxy redshifts - Results for five clusters

view Abstract Citations (47) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The use of the Kitt Peak IDS in determing galaxy redshifts : results for five clusters. Hintzen, P. Abstract The redshifts of 71 galaxies in five clusters determined using the Kitt Peak Image Dissector Scanner (IDS) are presented and the accuracy of velocities determined with the IDS system is discussed. Data were obtained from observations of absorption or emission lines in the range 3600-5400 A using the IDS on a 2.1-m telescope and effective apertures of 3.8 x 10.3 arcsec from galaxies belonging to the AWM 7 = NGC 1129, A 1213, A 1795, A 2589 and A 2666 clusters. Wavelength errors due to mechanical flexure, off-center guiding and spectrum noise are estimated to provide an uncertainty of + or - 1.21 A or 92 km/sec in measurements of a given spectrum, and comparison of the velocities determined by the Kitt Peak IDS with those determined by the Lick IDS supports the error value. Implications of the mean heliocentric redshifts and relativistically correct velocity dispersions obtained for the structure and membership of the AWM 7 cluster are discussed. Publication: The Astronomical Journal Pub Date: June 1980 DOI: 10.1086/112721 Bibcode: 1980AJ.....85..626H Keywords: Astronomical Photography; Galactic Clusters; Image Dissector Tubes; Red Shift; Ultraviolet Absorption; Velocity Distribution; Absorption Spectra; Galactic Structure; Radial Velocity; Astronomy full text sources ADS | data products NED (76) SIMBAD (9)

CCD Star Sensor for Fine Pointing Control of Spaceborne Telescopes

A star sensor for measuring small pointing errors in astronomical telescopes is described. By using solid-state imaging arrays (CCD's) to track guide-star images, this design realizes a number of performance advantages relative to more conventional approaches. Specific topics include star image position measurement, CCD sensitivity including color effects, and performance simulation results. Experimental results for CCD's operating at temperatures below 100 K are also summarized. Two telescope configurations are considered to illustrate the range of possible applications of this technology: 1) a large orbiting telescope for general astronomy requiring a multi-CCD sensor, and 2) a Space^Shuttle-based infrared observatory operating at 20 K. Although the requirements and configurations of these applications are widely different, the CCD approach offers substantial advantages to both systems. INE pointing control of large astronomical telescopes in space requires star trackers of extreme accuracy and stability. Pointing errors as small as a few percent of a star image diameter must be measured and corrected to prevent the resulting image motion from significantly degrading image quality. In this paper, we describe a general fine pointing sensor (FPS) design approach which uses charge coupled device (CCD) imaging arrays to track focal plane star images. Since CCD's provide accurate positional information regardless of where the image falls within the field-of-view, the proposed sensor design can accommodate wide variations in guide-star geometry without moving parts. This advantage, coupled with the fact that several stars can be tracked simultaneously (using one or several CCD's), makes the CCD approach a strong candidate for application to a variety of future space-based astronomical telescopes now being planned by NASA. CCD imaging arrays have several qualities which make them attractive for star tracking. A natural coordinate system is defined by the array of photosensitiv e elements which are not dependent on electromagnet ic deflection fields (as in the case for vidicons and image dissectors). Other advantages include high sensitivity, low operating voltage and the ability to survive exposure to strong light. The quantum efficiency of these detectors, combined with their efficient use of signal integration time (all elements integrate simultaneously), makes the noise performance of CCD trackers generally competitive with other approaches limited only by quantum noise (photon counting). In many cases, further noise reductions may be achieved by tracking several stars, simultaneously, on a single CCD.! One potential limitation of using CCD's for star tracking is the limited number of sensing elements (pixels) available with present arrays. Currently, the maximum array size is in the

Magnetic Disturbances in Image Dissector Spectrometry and Means to Overcome their Influence

Applying an image dissector for measurements with high precision as in spectrometry it is necessary to eliminate or control disturbances of the magnetic fields for deflection and focusing. It is demonstrated how disturbances from external fields are eliminated by specially designed shielding of the tube and its coil assembly. Magnetic disturbances originated from memory effects are reduced by making the remanence field equal before each individual measurement. This is achieved by applying a sequence of strongly varied magnetic fields.It is shown that magnetic disturbances must be eliminated or controlled in order to successfully use an image dissector echelle spectrometer as a rapid random access instrument.

Design Considerations Regarding Echelle Spectographs for Image Dissector Tubes

In this paper the optimization of echelle spectrographs for use with image dissector tubes is discussed. With all degrees of freedom in the choice of design parameters a rule for the optimization is given. It is also shown that there is a need for high-resolution image dissector tubes with larger photocathodes than those of the tubes available at present

New Image Dissector Tube Designs With Capability for High Resolution and Large Deflection Angles

In this paper the imaging properties of the two types of image dissector tubes available on the market are studied. It is found that the vidissector type shows astigmatism even at small deflection angles. The ring-dissector, which in order to be highly resolving must be operated at very high accelerating voltages, shows no image distortion with deflection. New image dissector tube designs are proposed, which both preserve the deflection properties of the ring-dissector tube and give high resolution at much lower accelerating voltages. The new tube designs also make the construction of very compact tubes possible as high deflection angles can be used without loss of resolution. The paper is a theoretical study. The electron images of different tube designs have been calculated numerically and are illustrated by spot diagrams.

Image dissector for size and position of statically suspended particles

The use of an image dissector to size and determine the coordinates of suspended particles is described. The device uses a laser light source and 90 degrees scattering. Volume scanning is accomplished using the internal x-y dissector scan and a mechanically stepped movement in z. Current application is toward the Atmospheric Cloud Physics Laboratory under development by NASA for a series of Space Shuttle experiments.

Automatic fluorescence microphotometer using an image dissector tube

An automatic fluorescence microphotometer using an image dissector tube as the fluorescence detector is described. The image dissector tube is used in the photon-counting mode of operation to allow precise intensity measurements of weak fluorescent spots. With the support of a laboratory-built microcomputer system, the instrument can automatically search for cells stained with fluorescent dye in the microscope field; then the detected cells are individually put in the measuring probe region to have their fluorescence intensities measured. Finally a fluorescence distribution histogram of stained cells is automatically generated and graphically presented. The instrument also allows a fluorescence intensity mapping operation utilizing the conventional raster scanning technique. To demonstrate the system's performance, DNA in rat liver nuclei stained with Feulgen dye was measured.

Spectrophotometry of Hot White Dwarfs from the Palomar-Green Survey

The Palomar-Green Survey (1977) contains a list of some 3000 spectroscopically classified stellar objects, chosen on the basis of ultraviolet excess. The survey covers 10,000 square degrees of the sky above |b|=30° with δ≥10° down to an average limiting B=16.2. A significant subset of this sample is a new catalogue of over 700 newly discovered hot degenerates (Green 1979). The combination of selection by color only without regard to motion and the large area covered resulted in the discovery of some rare, luminous degenerates and pre-degenerate objects. We report here on the first observations in a program of more detailed spectroscopic study of these objects, and display representative groups of common spectral or physical properties. These scans at 1.5-2.5 Å resolution were obtained with either the KPNO 2.1-m and intensified image dissector scanner or the Palomar 1.5-m with SIT spectrograph.

Digital picture analysis of the renal tubulus

Image analysis of tissues has to cope with two difficulties: (a) Most tissue elements are indistinct and their border appears fuzzy, and (b) The vast amount of information to be dealt with. These call for special procedures which are applied here to analysis of the histological image of the renal tubulus. Kidney histological sections have been photographed on a black and white negative transparency which was then scanned under computer control by an image dissector. The software utilized consists of routines for on-line image analysis such as feature detection of nuclei and area measurement of connected shapes. To store the relevant pictures in the computer the digitized image was transformed into isophotes. Each isophote was then encoded into an octal digit chain and stored as such. This procedure reduces drastically the image information content while preserving its relevant features.

Herbig-Haro objects associated with NGC 2264

view Abstract Citations (32) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Herbig-Haro objects associated with NGC 2264. Adams, M. T. ; Strom, K. M. ; Strom, S. E. Abstract Two complexes of emission knots have been discovered near the center of the young cluster NGC 2264. Intensified image dissector scanner spectra of three of these emission knots exhibit line intensities characteristic of Herbig-Haro (HH) objects. In the case of one of these knots, velocities of two condensations were derived from a relatively high-resolution spectrogram. The measured values of +34 km/s and +60 km/s compare with heliocentric velocities of +16.4 km/s for the H II region excited by the early-type main-sequence stars of the cluster, and +22 km/s for the molecular cloud complex located behind the H II region. It appears likely that these knots are HH objects associated with the molecular cloud complex and represent signposts of a star-formation episode triggered by propagation of an ionization front. Publication: The Astrophysical Journal Pub Date: June 1979 DOI: 10.1086/182989 Bibcode: 1979ApJ...230L.183A Keywords: Main Sequence Stars; Nebulae; Star Clusters; Stellar Evolution; Astronomical Spectroscopy; H Ii Regions; High Resolution; Hydrogen Ions; Molecular Excitation; Spectral Energy Distribution; Astrophysics; Herbig-Haro Objects:Open Clusters full text sources ADS | data products SIMBAD (5)

Computer image analysis of kidney histopathological sections

Human renal histological sections have been photographed on a black and white transparency and digitized. The digitizing camera, an image dissector, converts a 2 cm 2 picture into 400 × 400 numbers each representing the grey level value of the sampled point. The grey levels are represented in the computer by numbers ranging between 0–255. In this scale ‘0’ stands for black and 255, for white. The program provides 2 grey level thresholds, which outline a window through which the picture is scanned. Only structures, whose grey level value lies in the window range, are taken into consideration. The thresholds are set during digitization from the console switches. Image analysis is performed on-line in real time.