Results 191 to 200 of about 5,049 (222)

Nanometer displacement measurement using Fresnel diffraction

Applied Optics, 2012
We introduce a relatively simple and efficient optical technique to measure nanoscale displacement based on visibility variations of the Fresnel diffraction fringes from a two-dimensional phase step. In this paper we use our technique to measure electromechanical expansions by a thin piezoelectric ceramic and also thermal changes in the diameter of a ...
Ali Akbar, Khorshad, Khosrow, Hassani, Mohammad Taghi, Tavassoly   +2 more
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Computation of Fresnel diffraction

American Journal of Physics, 1986
A review and commentary is given of practical methods for computing the Fresnel diffraction patterns of circular and linear apertures. The general problem of approximating transcendental functions is also considered.
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Fresnel–Kirchhoff Diffraction Theory

2019
In this chapter we present the Fresnel theory of diffraction and its justification and improvement by Kirchhoff . In particular, we reproduce the calculation of the diffraction by the half-plane in the Fresnel-Kirchhoff theory .
Alexander Komech, Anatoli Merzon
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Fresnel diffraction supercontinuum generation

IEEE Journal of Selected Topics in Quantum Electronics, 2004
White supercontinuum (SC) produced from Fresnel diffraction was demonstrated in BK7 glasses using femtosecond laser pulses. For input pulse energy below the threshold for the onset of self-focusing and SC generation, an aperture was placed into the beam before the BK7 glass to redistribute the intensity by diffraction along the propagation axis to ...
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Efficient Fresnel-transform algorithm based on fractional Fresnel diffraction

Journal of the Optical Society of America A, 1995
The efficient Fresnel-transform algorithm (EFTA) is a computational tool that facilitates diffracted field analysis. The computational improvement that is achieved with the EFTA relative to the conventional double fast-Fourier-transform (FFT) algorithm results from the properties of fractional Fresnel diffraction.
H. Hamam, J. L. de Bougrenet de la Tocnaye   +1 more
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Fresnel vector diffraction integral

Technical Physics Letters, 1997
The Huygens-Fresnel principle modified for electromagnetic waves is used to achieve matching by generalizing the wave number to a complex value. In this way, it is possible to describe the field directly beyond a diffracting object.
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Partially coherent Fresnel diffraction by a slit aperture. III. Fresnel diffraction patterns

Optics Communications, 1973
Abstract The intensity distribution in the Fresnel diffraction pattern of a slit aperture illuminated with partially coherent light is obtained, as a function of the coherence condition across the aperture, by evaluating the formula developed in a previous paper.
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Fresnel diffraction with small apertures

Optical Society of America Annual Meeting, 1991
Fresnel diffraction experiments were conducted with small apertures and a spatially filtered He-Ne beam. The beam was left uncollimated so that a diverging wave was incident on the aperture. This allowed the input radius of curvature to have an effect in determining the location of the Fresnel patterns.
A. D. Struckhoff, J. L. Carlsten, Hal G. Kraus   +2 more
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Fresnel approximation applicability to ultrasonic diffraction

Applied Optics, 1980
A method based on Fresnel or parabolic approximation of the Helmholtz scalar wave equation is presented for calculating the diffracted amplitude when a plane monochromatic light wave is incident on a vessel filled with liquid irradiated by ultrasound. The intensities of the diffracted orders are calculated and compared with the Raman-Nath and Brillouin
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Edge-ringing and Fresnel Diffraction

Optica Acta: International Journal of Optics, 1975
Using the diffraction theory of aberrations, it is shown that edgeringing and Fresnel diffraction may be described as different regimes of the same physical process. Quantitative results are given, and some implications are briefly discussed.
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