Color Dispersion Research Articles

Multiwavelength Methods in Holographic Interferometry

Abstract Techniques are presented which take advantage of the wavelength dependence of various phenomena in holographic interferometry. Image-plane interferograms illuminated with light containing multiple wavelengths exhibit colour dispersion of the fringes. From this dispersion, we extract full-field information concerning displacement components which are not disclosed by monochromatic illumination.

Display of ordinary transmission holograms with a white light source

A method for displaying ordinary transmission holograms with a white light source is described, based on compensating the color dispersion in a broad band of the visible spectrum. Although some degree of image blur remains because of the size of the source, sharp and bright images at 30 cm from the hologram plane have been reconstructed.

Type I supernovae in the infrared and their use as distance indicators

New infrared data for 11 Type I supernovae are presented. These results, when combined with other published data for Type I supernovae, show that the light curves fall into two well-defined groups. The first more common type - Type Ia - shows strong, variable, unexplained absorption at 1.2 μm and probably at 3.5 μm, while the second type - Type Ib - shows no such absorption and a slower decline after maximum. The light curves of the Type Ia supernovae appear to have a dispersion in color and absolute magnitude of ±0.2 mag or less, making them potentially valuable for distance determination within the Local Supercluster.

The period-luminosity-abundance relations for galactic Cepheids

view Abstract Citations (21) References (56) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The period-luminosity-abundance relations for galactic Cepheids. Eggen, O. J. Abstract The median photometric parameters from intermediate and H-beta photometry of 106 Cepheids are used to test the Sandage-Tammann result that dispersions in the PL and PC relations are correlated with the amplitude of the light curves, as measured by the amplitude defect F(B). The correlation of both color and luminosity dispersions from mean PL and PC relations with F(B) are found to be the result of a correlation between abundance and amplitude. The short-period Cepheids (SPC) are distinctly divided between type C and normal Cepheids, with type C variables defined by F(B). The C-type and normal SPC are separated by 0.65 mag at a given period and abundance, or about 300 K at a given luminosity, with the C-type Cepheids being fainter and bluer, respectively. The light curves of nine-day Cepheids with strong humps may be misinterpreted in that the hump has mistakenly been taken for maximum light. Publication: The Astronomical Journal Pub Date: July 1985 DOI: 10.1086/113835 Bibcode: 1985AJ.....90.1278E Keywords: Abundance; Cepheid Variables; Stellar Luminosity; Astronomical Photometry; Light Curve; Milky Way Galaxy; Stellar Color; Astrophysics full text sources ADS | data products SIMBAD (103)

An experimental study of twin-screw extrusion-cooking of maize grits

The use of a twin-screw extrusion-cooker to process maize grits is described. The expansion, bulk density, colour and aqueous dispersion rheology have been related to the extrusion cooking variables: screw speed, feed rate, moisture content and barrel zone temperature. A pseudo-viscosity quantity has been defined to describe the extrudate viscosity at the die which was also related to the extrusion-cooking variables. The pressure and temperature profiles in the extruder were recorded together with the mechanical and thermal energy consumption as a function of the extrusion-cooking variables. These experiments with a highly instrumented cooking-extruder indicate the condition of the material in the barrel prior to formation of the product.

Some constraints on the color-magnitude diagram of giants in the galactic spheroid

view Abstract Citations (18) References (32) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Some constraints N the color-magnitude diagram of giants in the galactic spheroid. Bahcall, J. N. ; Soneira, R. M. ; Morton, D. C. ; Tritton, K. P. Abstract The color-magnitude diagram of giants in the Galactic spheroid is shown to be important in determining the number-color histogram of stars brighter than B = 19 mag. This result is demonstrated by comparing a standard Galaxy model with observations of 391 stars in a field in the direction of Aquarius (l = 36.5 deg, b = -51.1 deg). More than 80 percent of the spheroid stars and 40 percent of all stars in this magnitude range and direction are predicted to be giants. At most, a few percent of the spheroid stars in the current sample can lie on the main sequence bluer than the turn-off onto the giant branch near B - V approximately 0.4. The available observations suggest that the blue tip of the horizontal branch of the spheroid must be sparsely populated about a factor of 10 less than would be expected if the color-magnitude diagram of the spheroid were the same as diagrams for any of the globular clusters M3, M13, or M92. The total dispersion in colors (measurement errors and intrinsic dispersion) has a standard deviation in B - V color that is less than 0.2 mag. Publication: The Astrophysical Journal Pub Date: September 1983 DOI: 10.1086/161325 Bibcode: 1983ApJ...272..627B Keywords: Color-Magnitude Diagram; Galactic Structure; Giant Stars; Hertzsprung-Russell Diagram; Stellar Color; Stellar Magnitude; Subgiant Stars; Data Acquisition; Histograms; Late Stars; Spheroids; Stellar Structure; Astrophysics full text sources ADS | data products SIMBAD (6)

絵具および筆記具における分散

絵具および筆記具における分散

Projection-type white-light reconstruction of 3-D images from a strip-shaped hologram

Projection-type unidirectional holography is a promising three-dimensional imaging technique. However, the high cost of lasers in the reconstruction degrades its usefulness. This paper proposes a white-light-reconstruction version of the projection-type holography. The principle, design theory, and experiments are described. When a hologram is illuminated by a white light, the diffracted light exhibits color dispersion. The proposed method features the use of a holographically prepared diffraction grating for the compensation of the dispersion and of a simple device (called an optical channel) to cut off the nondiffracted components. Photographs of the reconstructed images show good agreement with the theory.

Measurement of Surface Color and Color Difference of Tablet Colorants by Tristimulus Colorimetry

The surface color of a series of color dispersions containing from one to three FD&C or D&C dyes suspended in a sucrose syrup was examined using tristimulus colorimetry. CIE (x, y) and Hunter (a, b) chromaticity data, determined directly from an integrating sphere colorimeter or from reflectance spectra and suitable calculations, were used to order materials by color on expanded chromaticity diagrams. Color difference was evaluated quantitatively from Hunter (a, b) data using the Judd color difference formula. Quality control specifications were established either by defining areas of acceptable color by applying limits to the chromaticity coordinates of color standards or by requiring the Judd color difference to be less than a specific number of National Bureau of Standards standard units. This method eliminates the subjective character of color evaluation and permits the quantitation of visual color difference. These differences can be used, in conjunction with defined color standards, to develop color specifications for tablet colorants, finished tablets, and liquid and cream pharmaceutical preparations.

The structure of late type stars and the Hayashi track

A topological approach in the HR diagram is given for the occurrence and the characteristics of convective envelopes in population II stars. The location of the Hayashi track and of the Red Giants branch are both investigated for various assumed masses of the stars and chemical compositions of the convective layers. An analysis is performed on the influence of the assumed mixing length. The observational consequences of a possible mass loss is discussed for both the Red Giants and the Asymptotic branches. Possible causes for separation between these two branches are briefly examined. The case of the globular cluster ω Cen is investigated, in order to give some suggestions for a large dispersion in colours observed among the giants belonging to this cluster.

The Horizontal Branch and the Cosmic Abundance of Helium

Stellar models deriving their luminosities from helium burning in the core and hydrogen burning in a shell are investigated for helium core masses of 0.425, 0.450, and 0.475 M/sub sub solar /, and for total masses ranging from 1.35 M/sub sub solar / down to the respective core masses. The investigated helium and heavy-element abundances lie within the ranges (0.25, 0.45) and (0.0001, 0.06) respectively. The readjustment of the hydrogen bunning shell on the horizontal branch is studied. The effect of a changing core mass as a function of the width of this hydrogen profile is used to extend the validity of previous zero-age-horlzontal-branch computations with steep profiles into the regime of broadened, typical horizontal-branch profiles. The color dispersion of stars along the horizontal branch is found to be about twice as sensitive to a core-mass spread than to an equal spread in total mass. Preliminary evidence for the existence of a core-mass spread along the blue horizontal branches of globular clusters is presented. A new method for determining the helium abundances of horizontal-branch stars is presented. The method is shown to be independent of the heavy-element abundance, of the mixing length, of small changes in the hydrogen composition profile,more » and independent of the main effects of evolution during the core-helium burning phase. Comparisons with available observations indicate that the helium abundance of the halo population of the Galaxy is greater than 0.30 plus or minus 0.04 by mass fraction. The helium abundances of seven open clusters average to 0.23, with an uncertainty of 0.10 to 0.20. This inverse correlation between the helium abundance and angular momentum of the populations in our Galaxy is supported by a preliminary study of helium abundances obtained from other methods. The cosmological implications of this inverse'' helium composition gradient suggest that either some helium enriching mechanism acted during the protogalactic collapse in regions of high density and low metal abundance or (and) the chemical inhomogeneities were created in the primeval fireball. (auth)« less

Newton's search for a mechanistic model of colour dispersion: A suggested interpretation

1. Early Attempts Newton's earliest notebook, dating from 1664-5, contains some evidence showing that closely upon his discovery of the multiple indices of refraction, he was trying to construct some mechanistic models to explain it. Two features stand I wish to express my deepest gratitude to D. T. Whiteside for the many exciting discussions we had, for his deeply enlightening constant criticism, and for the incessant and generous help he extended to me towards the writing of this paper. I wish also to thank R. Westfall and S. Sambursky who read and criticised an early version of this paper, and finally my friend Y. Elk an a whose help actually enabled me to write the present version. 1 Arch. Hist. Exact Sci., Vol. 1 1

Hologram Reconstruction by Incoherent Light. II. Experimental Results

The characteristics of holograms reconstructed by incoherent light being emitted by high-pressure mercury arc lamp, GaAs laser diode and GaAs electroluminescent diode are experimentally exhibited mainly in the arrangement of lensless Fourier transform after having been recorded by coherent light of He–Ne or Ar laser. The degree of image blur from color dispersion and by the size of the reconstructing light source confirms the theoretical foundation described in the preceding paper. Furthermore, the degree of the improvement of the compensated images with a proper diffraction grating (or hologram) is clearly shown. The reconstructed images of transparent objects are obtained with or without the compensating grating. The experiments on the magnification and the distortion caused by the wavelength ratio of reconstructing to recording light are also performed.

Hologram Reconstruction by Incoherent Light. I. Theoretical Foundation

Theoretical considerations are presented on characteristics of holograms reconstructed by incoherent light after recorded by coherent light. The following problems are discussed: (1) The generalized formula for the reconstructed image by incoherent light, (2) image blur from color dispersion (the lack of temporal coherence) and by the reconstructing light source size (the lack of spatial coherence), (3) the distortion of the reconstructed images depending on the wavelength ratio of reconstructing to recording light, (4) the degree of the improvement for the achromatized reconstructed images with the diffraction grating (or hologram) for compensating color dispersion.

Primary Stabilization of a 1 MeV Electron Accelerator

Chromatic aberration is a major obstacle in the attempt to achieve near atomic resolution in electron microscopes. In analogy to dispersion of colors in a glass lens, nonuniform velocities of the illuminating electrons will reduce the resolution of an electron microscope lens. Instability of the accelerating potential is an important cause of these nonuniformities. To achieve resolution on the order of 1 to 5 Å, accelerating voltage must be stable to approximately 3 parts per million. To achieve these resolutions, a highly stabilized 1 MeV linear electron accelerator was developed. One of its two 15 in. (38 cm) accelerating tubes will provide a velocity stabilized electron beam source for a high resolution electron microscope. Electron acceleration occurs through a constant potential divider. A Van de Graaff type charge carrying pellet string provides the accelerating voltage. The primary or coarse control system for the linear electron accelerator compares the high voltage terminal voltage as detected with an accurate voltage divider to a reference cell voltage. Error signals are amplified to control the voltage on a capacitive liner. Control is accomplished by a voltage control of the cylindrical capacitive liner surrounding the high voltage terminal. The low frequency fluctuations in accelerator voltage maintained by this primary loop are less than 0.1% to permit utilization of a fine control loop with a spectrometer beam analysis control to achieve fine voltage stability of 3 parts per million.

Experimentum crucis

Chronology 1620 Instantice Crucis as introduced by Bacon 1648 Uni-coloured rays sent through prisms (Marci) 1665 Colour dispersion behind pinholes (Grimaldi) 1665 Hooke coins the phrase Experimentum Crucis 1 666- Newton dissects sunrays with prisms and pinholes 1672 Newton publishes an Experimentum Crucis 1672- Controversies about the experiment 1681 Mariotte rejects it 1704 Is there any Experimentum Crucis in the ? 1715- Desaguliers exhibits variants o f the experiment 1722 A Paris edition o f the Opticks. Its prefaces 1722 A final substitute (?) for the Experimentum Crucis Introduction From 1666 onwards Newton planned and executed a great variety of prism experiments, but in his celebrated treatise about ‘Light and Colors’ (1) he described only three of them. If we trust in Newton’s ‘historicall narration’ (2) his curiosity was first aroused by the oblong shape of the solar image, which according to traditional geometrical optics should have been circular . Newton said that he figured out several hypotheses to account for this anomaly, and by removing these ‘suspitions’ systematically he was led to an Experimentum Crucis , which proved ‘that Light consists of Rays differently refrangible’. His narrative seems to imply that he carried out the whole investigation within a few sunny days in spring 1666.

Vat Dyeing of Cotton Fabric by Pigmentation Methods

A brief survey of practical vat pigment padding procedures is supplemented with data on the physical properties of suitable dyes. The effect of particle size on rate of reduction is discussed in relation to its practical implications, as well as factors such as colour yield, dispersion stability and migration effects during drying. The use of a new organic polyelectrolyte as a migration inhibitor is described.

Colors of elliptical and spiral nebulae in the Corona Borealis cluster.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Colors of elliptical and spiral nebulae in the Corona Borealis cluster. Whitford, A. E. Abstract Colors of four elliptical and seven spiral nebulae in the Corona Borealis cluster have been measured photoelectrically at Mount Wilson. The previous colors in clusters of nebulae reported by Stebbins and Whitford1 showed an unexplained color excess, but the objects measured were all elliptical nebulae, and therefore represented pure population II. The spiral objects in the Corona Borealis cluster were selected as the most remote examples of population I with a known distance; spirals have not been resolved in the Bootes cluster. For the four ellipticals the international color excess is O.28 mag., of which 0.15 mag. is not accounted for by the red shift. Intermediate type spirals also show a residual excess, but the interpretation is clouded by uncertainty about the classification. The four spirals classified as type Sc, with the largest proportion of population I, show a mean excess of O.09 mag., which with a calculated red-shift effect of o.15 mag., leaves a residual of -o.o6 mag. The negative residual is probably not significant, on account of the intrinsic color dispersion of the objects and the observational difficulties in measuring faint diffuse spirals. But the difference between ellipticals and late spirals favors the hypothesis that the unexplained excess is a time effect in population II, as suggested by Schwarzschild, and not a space-reddening effect caused by intergalactic material. The red super- giant stars which have burned themselves out and faded in nearby ellipticals, but which were present 130 million years ago in the Corona nebulae, would add only slightly to the mass and to the photographic luminosity. In evaluating nebular counts to the faintest magnitude limits, however, a very appreciable luminosity correction would be necessary, particularly on red plates. I. A. J. 53, 206, 1942; Ap. J. io8, 413, 1948. Washburn Observatory, Madison, Wis. Publication: The Astronomical Journal Pub Date: 1949 DOI: 10.1086/106311 Bibcode: 1949AJ.....54S.138W full text sources ADS |

Discussions of Color Index and Spectral Type.

view Abstract Citations (9) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Discussions of Color Index and Spectral Type. Seares, Frederick H. ; Joyner, Mary C. Abstract Color indices from the Mt. W. Polar Catalogue and numerous observations of spectral types made at Upsala, Harvard, Bergedorf, Yerkes, and Mount Wilson give the following results: 1. Information on the consistency of the color indices-For stars brighter than m = 9.0 and types earlier than GO the colors require a correction depending on the magnitude (Fig. 3). 2. A determination of the spectrum-color relation (Table 7, Fig. 4; international system for color, HD for spectra).-Freed from the effects of space absorption, C for A0 is -0.15 mag., in agreement with results from stars in unobscured regions. 3. A determination of the mean color excess E as afunction of distance (Table 11, Fig. 5).-To 400 parsecs (distance corrected for absorption) E increases at the rate of about 0.06 mag. per 100 parsecs. From 450 to about 700 parsecs it has an approximately constant value of 0.27 mag., as though the obscuring cloud ended a little beyond 400 parsecs. The corresponding absorptions for photographic and photovisual light (X' law) are 1.3 and 1.0 mag., respectively. The foregoing results leave for each star a residual (about 1350 in all) which includes the influence of deviations from the mean absorption E, of dispersion in color for stars of the same spectrum, and of ob- servational errors in color and in spectrum. The statistical relationships are such that these influences can be partially separated and estimated. Local zero-point errors (ME) in C for the Mt. W. Polar Catalogue are about ± 0.015 mag. (Table 12, relation [19]). Deviations from the mean E are appreciable but apparently local; the obscuring cloud extends over the polar cap north of +80° with little evidence of progressive change from side to side (Table 12, Figs. 6, 7). Except for types later than about K2, the dispersion in color for the same spectrum averages less than ± 0.035 mag. (Table 13, relation [25]). For late K and M giants it seems to be 0.1 mag. or more. Spectral-classification errors (Tables 14-14b) for early A's and for gK stars are generally smaller than for intermediate fypes. Slit spectrograms naturally show a higher precision than objective-prism plates; the errors for MW (only 53 stars available) average from 0.6 to 0.8 those for the HD in the polar re- gion, which for most types seem to be less than the average for the HD as a whole Publication: The Astrophysical Journal Pub Date: November 1943 DOI: 10.1086/144572 Bibcode: 1943ApJ....98..261S full text sources ADS | Related Materials (1) Reprint: 1943CMWCI.684....1S

Color Dispersion in the Astigmatic Eye

Color Dispersion in the Astigmatic Eye