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  • 1985-1989  (2)
  • 1960-1964  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Retinal visual acuity with pattern VEP normal subjects and reproducibility (1986)
    Springer
    Graefe's archive for clinical and experimental ophthalmology 224 (1986), S. 160-164 
    Details
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Retinal visual acuity was determined using an objective method by means of VEP. Sixty subjects with subjective visual acuity ranging from 20/25 to 20/12 were measured with a computer-controlledlaser interferometer, using interference fringes modulated in counterphase as pattern-reversal stimulus. Steady-state VEPs taken at different spatial frequencies were evaluated byFourier analysis andlinear regression. Objective retinal acuity was calculated as the intersection between the linear regression line and the linear scaled spatial frequency axis. In 68% of all cases, the difference between objective and subjective visual acuity was less than ±5.1 cycles per degree (c/d) (±15.4% referred to subjective acuity); in 86%, the difference was less than ±7.7 c/d (±23.1%).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02141491
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Die Anwendung des normierten Vašiček-Verfahrens bei nichtabsorbierenden Einfachaufdampfschichten auf Glasträgern (1962)
    Springer
    The European physical journal 170 (1962), S. 376-392 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The author has modifiedVašiček's polarimetric theory to a graphic method for determination of optical constants of thick homogeneous films on glass carriers. The method is verified for single layers deposited by heating salts. The kind of salt determines the gradient of the refractive index. This gradient and the state of the surface of the glass are responsible for deviations from the theoretical curves. A suitable method has been found for determining the refractive index and the thickness of the deposited film. In a modified form the method can also be used for inhomogeneous films. Sometimes it is possible to determine even a change in thickness less than 10 Å during the deposition of the film. The thickness can be calculated accurately only by measuring at three different light-frequencies, because the curves are periodical. The values for the different light-frequencies agree well with each other differing only by about 5%. The agreement is much better for films thicker than 10000 Å. The thickness of the films as obtained by applying this method is almost identical with the one given by an interference microscope.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01378475
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Über ein graphisches Verfahren zur polarisationsoptischen Bestimmung von Dicke und Brechungsindex beliebig dicker, nichtabsorbierender, homogener Schichten auf Glas (1962)
    Springer
    The European physical journal 168 (1962), S. 353-369 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Vašiček's universal method for determining the optical constants of nonabsorbing, homogeneous layers of any thickness on glass has been limited to the special case of ligth incidence under the polarizing angle of the glass carrier. This enables one to base the measurements on a reference glass carrier of well known refractive index, and simplifies the relationship of the variables. After calculating all parameters and computing some normalizing curves for this particular reference carrier, it is possible, to evaluate graphically all polarimetric measurements for any kind of glass carrier or wavelength and for all data of the layers as thickness or refractive index. The feasibility of the normalizing process has been proved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01387033
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Die Erprobung des normierten Vašiček-Verfahrens bei inhomogenen, nichtabsorbierenden Schichten auf Glasträgern (1962)
    Springer
    The European physical journal 170 (1962), S. 393-408 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract By the use ofVašiček's polarimetric method for a single layer differences from the theoretical curves have been observed, which can not be theoretically explained. These differences can be increased experimentically by the deposition of double films. The author suggests four rules, by which the inhomogenity of the films can be calculated from the measured curves. It is possible to determine the thickness and refractive index quantitatively and the index gradient approximately. For the same salt all the four possible types of inhomogenity can be produced. With the rules the differences in the results can be eliminated. The fifth rule limits the applicability of the four other rules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01378476
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    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Electrophysiological assessment of the human depth-perception threshold (1987)
    Springer
    Graefe's archive for clinical and experimental ophthalmology 225 (1987), S. 429-436 
    Details
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The cortical response to stereoscopic stimuli was measured as a function of disparity using visual evoked potentials (VEP). The stereoscopic stimulus consisted of a dynamic random-dot pattern that portrayed a three-dimensional horizontal grating. Disparity of the grating was variable between 0 and 18 arc min, step size being 4.22 arc s. Evoked responses were recorded using a “random-sequence sweep technique.” The VEP amplitude increased approximately linearly with the logarithm of disparity and allowed an estimation of the stereo threshold by linear extrapolation. The evoked potential estimates of the stereo threshold of 16 subjects were compared to psychophysically obtained thresholds. Several threshold-estimation techniques are discussed. Evoked potential and psychophysical threshold estimates had the lowest discrepancy when the VEP amplitude was linearly extrapolated to the logarithmic disparity axis. The difference between the evoked potential estimate and the psychophysical threshold was less than 20% in 56% of all cases; 16 of 18 cases (89%) agreed within a factor of 2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02334171
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    Paper (German National Licenses)
    Fulltext
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