Showing papers on "Physical optics published in 1968"
TL;DR: In this article, the authors studied the effect of nonlinear optical effects on self-focusing beams in the field of self-focus and Parametric Amplification in a nonlinear medium.
Abstract: CONTENTS 1. Introduction 609 2. Geometrical Optics of a Nonlinear Medium (Equations, Focal Points, Nonlinear Aberrations, Nonstationary Processes) 617 3. Wave Optics of a Nonlinear Medium (Diffraction Corrections to the Self-focusing Length, Formation of Proper Optical Waveguide, Nonstationary Processes) 624 4. Nonlinear Optical Effects in the Field of Self-focusing Beams (Stimulated Scattering in Liquids, Experimental Data, Self-focusing and Parametric Amplification) 629 5. Conclusion (Unsolved Problems, Diffraction in Nonlinear Interactions) 632 Cited Literature 634
881 citations
TL;DR: In this article, the equivalence of the angular-spectrum representation and one of Rayleigh integral transforms is demonstrated, making use of conditions under which the integral formula exists as the unique solution to a certain class of boundary-value problems.
Abstract: The representation of the electromagnetic field as an angular spectrum of plane waves is becoming increasingly popular in the treatment of certain problems in physical optics. In this paper the equivalence of the angular-spectrum representation and of one of Rayleigh’s integral transforms is demonstrated. Making use of conditions under which the Rayleigh integral formula exists as the unique solution to a certain class of boundary-value problems, conditions under which the angular-spectrum representation is valid are discussed.
106 citations
01 Oct 1968
TL;DR: In this paper, the integral for the average scattered power from a rough surface obtained from physical optics is shown to be proportional to the joint probability density function for the surface slopes in the high-frequency limit.
Abstract: The integral for the average scattered power from a rough surface obtained from physical optics is shown to be proportional to the joint probability density function for the surface slopes in the high-frequency limit.
66 citations
TL;DR: In this article, an integral equation method is used to calculate intensities of the first-order lines scattered by longitudinal and transverse acoustic waves in an infinite slab of birefringent crystal.
Abstract: The theory of Brillouin scattering is extended to incorporate birefringence. The necessary modifications to the Bragg laws are derived by the methods of physical optics. An integral equation method is used to calculate intensities of the first-order lines scattered by longitudinal and transverse acoustic waves in an infinite slab of birefringent crystal. This calculation also differs from those of previous authors in taking full account of internal reflection. Depletion of the incident beam is accounted for. No restriction is made to acoustic propagation parallel to the crystal faces. The intensity formulas for various cases of acoustic mode and incident optical polarization are found to differ in geometrical structure, and the differences can alter the intensities substantially.
36 citations
01 Oct 1968
TL;DR: In this article, the scattering of plane waves from perfectly conducting cylinders is studied, using the condition that the total field inside the cylinders must be zero, and it is shown that the surface current density can always be expressed as a sum of proper modes.
Abstract: The scattering of plane waves from perfectly conducting cylinders is studied, using the condition that the total field inside the cylinders must be zero. It is shown that the surface current density can always be expressed as a sum of proper modes. In general, fewer modes are required for calculating the scattered far field than are required for calculating the surface current density to the same accuracy. Two new approximate methods are introduced. These methods complement the method of physical optics, and the more accurate of them is suitable for calculating the scattering over a wide range of bistatic angles.
23 citations
18 citations
TL;DR: The feasibility of using a direct numerical integration of physical optics fields for computing radiation patterns of ground-based HF-VHF antennas in the presence of known ground irregularities is examined in this article.
Abstract: The feasibility of using a direct numerical integration of physical optics fields for computing radiation patterns of ground-based HF-VHF antennas in the presence of known ground irregularities is examined The initial study treats a special case of a line source above a perfectly conducting plane with a semicylindrical boss This case permits a comparison of results computed using physical optics formulations to the exact values The agreement is gratifyingly close, which justifies an extension of such a study to a three-dimensional case
12 citations
01 Jan 1968
TL;DR: In this paper, a high-frequency method for the electromagnetic scattering by two perfectly conducting spheres is presented which employs conventional geometric optics and a modified geometric diffraction theory, and the method is believed applicable for spheres of radius equal to or greater than λ/2.
Abstract: A high-frequency method for the electromagnetic scattering by two perfectly conducting spheres is presented which employs conventional geometric optics and a modified geometric diffraction theory. Numerical results indicate good agreement with experiment and theoretical results using a different approach. The method is believed applicable for spheres of radius equal to or greater than λ/2.
9 citations
TL;DR: In this paper, an expression for n in terms of known numerical aperture of the objective was derived for the uniaxial crystal KH 2 PO 4 and the expression takes nonparaxial behavior into account.
Abstract: Math., an expression for n is derived in terms of known numerical aperture of the objective. The expression takes nonparaxial behavior into account. Uncor. and cor. values of n measured with polarized 589-mmu light for the uniaxial crystal KH 2 PO 4 are tabu lated and agree well with literature values. -- AATA
8 citations
TL;DR: In this article, it was shown that consistent results can be obtained in first-order optics when the ray coordinates are assumed to be infinitesimal at the outset, but only after the exact relations have, in principle, been obtained.
Abstract: Contradictory results may be obtained in first-order optics when the ray coordinates are assumed to be infinitesimal at the outset. Consistency is assured if the approximations of first-order optics are made only after the exact relations have, in principle, been obtained. This is illustrated, for the case of imagery in a neighborhood of an arbitrary base ray lying in the plane of symmetry of a plane-symmetric system, by a discussion of the astigmatism of a first-order pencil.
4 citations
TL;DR: In this paper, a graphical comparison between exact and approximate backscattering widths for dielectric cylinders with both polarizations, up to relatively high frequencies, is shown, and some of the phenomena responsible for the behavior of the scattering cross section are examined and interpreted physically.
Abstract: A graphical comparison is shown between exact and approximate backscattering widths for dielectric cylinders with both polarizations, up to relatively high frequencies. Some of the phenomena responsible for the behavior of the scattering cross section are examined and interpreted physically.
01 Jan 1968
01 May 1968
TL;DR: In this article, the authors describe a digital computer program which uses the physical optics approximation to calculate the scattering properties of convex perfectly conducting targets with arbitrary shape, such as spheroids, ogive, and cone.
Abstract: : This report describes a digital computer program which uses the physical optics approximation to calculate the scattering properties of convex perfectly conducting targets with arbitrary shape. The target shape is described in terms of the coordinates of a large number of points on the surface. The program handles bistatic as well as backscattering problems. The input data specify the frequency, the incidence angles and the scattering angles. In the CW case, the output data give the complex elements in the scattering matrix. The program also handles the pulse case where the incident waveform has a finite number of cycles. Graphs are included to illustrate typical results for the following target shapes: sphere, spheroids, ogive, and cone.
TL;DR: In this article, the authors deduced a formula for the classical cross-section in the scattering of particles by fields of force with a term which is a random function of time.
Abstract: We deduce a formula for the classical cross-section in the scattering of particles by fields of force with a term which is a random function of time. The results are generalized to geometrical optics, and some examples for which the formulas hold are mentioned.