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  • 1
    Electronic Resource
    Electronic Resource
    Borrmann-like anomalous effects in volume holography (1980)
    Springer
    Applied physics 22 (1980), S. 335-353 
    Details
    ISSN: 1432-0630
    Keywords: 42.30 ; 42.10 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In this review, a surgey of the evidence for the appearance in volume holography of certain anomalous effects (akin to the Borrmann effect in x-ray crystallography) is conducted, with reference to both experimental observations and theoretical models. The main part of the paper is devoted to the application of a recently-developed two-dimensional coupled-wave theory (an extension of Kogelnik's one-dimensional theory) to the modelling of such anomalous phenomena. Extensive calculations based upon this theory, for the case of Gaussian wave incidence on a uniform mixed grating for various boundary conditions, are presented in a unified two-dimensional description of Borrmann-like effects in volume holography. In particular, certain qualitative predictions of the dynamical theory of x-ray diffraction are expressed quantitatively in the two-dimensional theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00901055
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Thick grating focussing-device-design using poynting-vector-optics (1981)
    Springer
    Applied physics 26 (1981), S. 37-42 
    Details
    ISSN: 1432-0649
    Keywords: 42.80 ; 42.82 ; 42.10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Novel thick grating focussing and de-focussing devices are described which employ uniform phase gratings with special boundary shapes. The analysis used is based upon an eigenmodal approach to Kogelnik's coupled-wave equations, akin to the dynamical theory of x-ray diffraction. The relationship between the direction of phase progression of the coupled-waves at Bragg incidence, and the direction of the Poynting vector is carefully delineated. As a consequence, a new technique-Poynting Vector Optics — is suggested as potentially an important means of designing thick gratings to fulfil certain beam processing roles, especially in integrated optics applications. The two-dimensional coupled-wave equations are briefly employed to illustrate the effectiveness of a particular focussing device.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00702685
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  • 3
    Electronic Resource
    Electronic Resource
    Bragg diffraction of gaussian beams by thick gratings: Numerical evaluations by plane-wave decomposition (1982)
    Springer
    Applied physics 28 (1982), S. 383-390 
    Details
    ISSN: 1432-0649
    Keywords: 42.10 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The validity of 2-D coupled-wave theory is investigated for the case of Bragg diffraction of a Gaussian beam by a thick unslanted phase grating in transmission mode. Fourier plane wave decomposition theory, as presented in a companion article, is used to test 2-D coupled-wave theory under circumstances when its validity is in question, namely when the incident distribution is very narrow or fast-varying, or when the parameterv o, due to Kogelnik (1969), which is proportional to the product of coupling rate and grating thickness, is very large. Numerical evaluations of the field patterns at output from the grating, obtained using plane-wave decomposition, are used to explore the effect of the gradual violation of the conditions (from the previous article) under which 2-D coupled-wave theory is valid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686370
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  • 4
    Electronic Resource
    Electronic Resource
    Bragg diffraction of finite beams by thick gratings: Two rival theories (1982)
    Springer
    Applied physics 28 (1982), S. 63-72 
    Details
    ISSN: 1432-0649
    Keywords: 42.10 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Two rival techniques used in the analysis of Bragg diffraction of two-dimensional light beams by thick unslanted phase gratings, namely Fourier plane wave decomposition and 2-D coupled-wave theory, are compared. The advantages and regions of applicability of each are discussed, and the conditions found under which they yield identical results. In particular, the results of plane-wave decomposition are used to provide quantitative conditions for validity of 2-D coupled-wave theory. These conditions are not easily derived using any other technique, and set quantitative limits to how narrow or fast-varying the incident distribution may be before 2-D coupled-wave theory fails. It is also shown that 2-D coupled-wave theory is inadequate when the parameterv 0, due to Kogelnik (1969), which is proportional to the product of coupling rate and grating thickness, is very large.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00693894
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  • 5
    Electronic Resource
    Electronic Resource
    Thick-grating non-divergent focussing device: 2-D analysis (1981)
    Springer
    Applied physics 26 (1981), S. 89-98 
    Details
    ISSN: 1432-0649
    Keywords: 42.80 ; 42.82 ; 42.10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The two-dimensional analysis of a recently reported thick grating Bragg diffraction focussing device is carried out using Solymar's coupled-wave approach. It is shown that the device is capable of operating as a non-divergent lens with beam contraction ratios of better than 100:1, and conversion efficiencies of nearly 100%. It is also shown that it can operate as a novel kind of Fourier spectrum analyser, the focussed diffracted intensity being proportional (as a function of Bragg condition violation) to the modulus squared of the Fourier transform of the incident finite beam. The focussing properties are studied as functions of incident beam profile, width and position, grating strength and Bragg condition violation. Poynting vector optics is used successfully to predict (in conjunction with the dispersion surfaces of x-ray dynamical theory) the off-Bragg behaviour in the focal plane. It is likely that the device could be used as avariable ratio beam contractor in integrated optics, where the grating strength could be controlled (interdigital electrode system) electrooptically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01284908
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  • 6
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    Dust in space and comets; Proceedings of the Topical Meeting, Graz, Austria, June 25-July 7, 1984 (1984)
    In:  Other Sources
    Details
    Publication Date: 2016-03-09
    Description: Consideration is given to: the mass loading of planetary magnetospheres by rocky satellites; the effects of electrostatic forces on the vertical structure of planetary rings; and dust motion in Jupiter's tilted magnetic field. Other topics include: IRAS observations of cometary dust; dust environment models for Comet P/Halley; plasma processes and solar wind interaction; and cometary interplanetary field enhancements in the solar wind. Consideration is also given to: the impact of dust grains on fast fly-by spacecraft; EUV observations of Comet Halley; and the thermal model and thermo-mechanical stresses in cometary nuclei.
    Keywords: ASTROPHYSICS
    Type: (ISSN 0273-1177)
    Format: text
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  • 7
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    A possible observation of a cometary bow shock (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: In February, 1982, an unusual enhancement of the IMF was observed by the Pioneer Venus orbiter at 0.72 AU. The three discontinuities within this large disturbance, previously suggested to be due to the possible passage of a comet, are examined in view of the alternative possibility of their representing the first observation to date of a cometary shock. It is noted that number density, temperature, and velocity changes, as well as the magnetic structure of the discontinuities, are consistent with this hypothesis.
    Keywords: ASTROPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 11; 1022-102
    Format: text
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  • 8
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    Multiple spacecraft observations of interplanetary shocks Four spacecraft determination of shock normals (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: ISEE 1, 2, 3, IMP 8, and Prognoz 7 observations of interplanetary shocks in 1978 and 1979 provide five instances where a single shock is observed by four spacecraft. These observations are used to determine best-fit normals for these five shocks. In addition to providing well-documented shocks for future investigations these data allow the evaluation of the accuracy of several shock normal determination techniques. When the angle between upstream and downstream magnetic field is greater than 20 deg, magnetic coplanarity can be an accurate single spacecraft method. However, no technique based solely on the magnetic measurements at one or multiple sites was universally accurate. Thus, the use of overdetermined shock normal solutions, utilizing plasma measurements, separation vectors, and time delays together with magnetic constraints, is recommended whenever possible.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; June 1
    Format: text
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  • 9
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    Upstream waves and particles /Tutorial Lecture/ (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The plasma waves, MHD waves, energetic electrons and ions associated with the proximity of the region upstream from terrestrial, planetary and interplanetary shocks are discussed in view of observations and current theories concerning their origin. These waves cannot be separated from the study of shock structure. Since the shocks are supersonic, they continually overtake any ULF waves created in the plasma in front of the shock. The upstream particles and waves are also of intrinsic interest because they provide a plasma laboratory for the study of wave-particle interactions in a plasma which, at least at the earth, is accessible to sophisticated probing. Insight may be gained into interstellar medium cosmic ray acceleration through the study of these phenomena.
    Keywords: ASTROPHYSICS
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  • 10
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    Far-infrared polarization of the Kleinmann-Low Nebula (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Further data on the polarization of the far-infrared (wavelength greater than 40 microns) emission from the Orion Nebula shows no evidence for polarized emission by aligned grains. Results at wavelength about 71-115 microns are consistent with a small (about 1.5%) absorption-induced polarization with about the same position angle on the sky as the polarization measured at shorter wavelengths.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 85; Oct. 198
    Format: text
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