Tous les articles par Jacques

FOCUSING OF 52-GHZ BEAMS BY CYLINDRICAL MIRRORS (SHORT PAPERS)

J. A. Arnaud, J. T. Ruscio, D. C. Hogg

Microwave Theory and Techniques, IEEE Transactions on  (Volume:20 ,  Issue: 5 ), 344 – 345, May 1972

ABSTRACT

The possibility of using inexpensive commercial glass mirrors for refocusing and redirecting millimeter-wave beams has already been investigated; such beams would be useful for distributing large quantities of information in cities. Interference is expected to be minimal as a result of the close confinement of the beams. We report preliminary experiments made in the 50-55-GHz band, using a swept backward-wave oscillator (BWO) as a source.

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MODE COUPLING IN FIRST ORDER OPTICS

J. Arnaud

Journal of the Optical Society of America,  Vol. 61,  Issue 6, pp. 751-758,  (1971)

ABSTRACT

A simple procedure is described to obtain the modes of propagation in square-law lens-like media. This procedure consists of evaluating the geometrical-optics field created by a point source at the input plane of an optical system (called mode-generating system) with nonuniform losses. An expansion of the field in power series of the coordinates of the point source gives the modes of propagation. In the case of optical resonators, the mode-generating system is described by the modal matrix of the resonator round-trip ray matrix. This representation of modes by point sources allows the coupling factor between two modes with different parameters (beam radii, wave-front curvatures, and axes) to be evaluated without integration. Only matrix algebra is used. In the general three-dimensional case, the coupling factor is expressed as a product of Gauss functions and Hermite polynomials in four complex variables. The quantities introduced are generalized ray invariants.

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NONORTHOGONAL OPTICAL WAVEGUIDES AND RESONATORS

J. A. Arnaud

Bell System Technical Journal, Volume 49, Issue 9, pages 2311–2348, November 1970

ABSTRACT

The modes of propagation in optical systems which do not possess meridional planes of symmetry (nonorthogonal systems) are investigated in the case where the effect of apertures and losses can be neglected. The fundamental mode of propagation is obtained with the help of a complex ray pencil concept. An integral transformation of the field, based on a quasi-geometrical optics approximation and a first-order expansion of the point characteristic of the optical system, is given; it shows that the complex (three-dimensional) wavefront of the fundamental mode is transformed according to a generalized “ABCD law.” A simple expression is also obtained for the phase-shift experienced by the beam. The higher order modes of propagation are obtained from a power series expansion of the fundamental mode. These higher order modes are expressed, in oblique coordinates, as the product of the fundamental solution and finite series of Hermite polynomials with real arguments. In the special case of systems with rotational symmetry, these series reduce to the well-known generalized Laguerre polynomials. The theory is applicable to media such as helical gas lenses and optical waveguides suffering from slowly varying deformations in three dimensions. Nonorthogonal resonant systems are also investigated. An expression for the resonant frequencies, applicable to any three-dimensional resonator, is derived. Numerical results are given for the resonant frequencies and the resonant field of a twisted path cavity which exhibits interesting properties: the usual polarization degeneracy is lifted and the intensity pattern of all of the modes possesses a rotational symmetry.

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FOCUSING AND DEFLECTION OF OPTICAL BEAMS BY CYLINDRICAL MIRRORS

J. A. Arnaud, J. T. Ruscio

Applied Optics, vol 9, number 10, october 1970

ABSTRACT

An optical system incorporating two closely spaced cylindrical mirrors is described. By properly orienting the mirrors in space, an incident beam can be focused at any desired point within a large volume. This simple periscopic system, which provides variable focal lengths and deflection angles, is applicable to optical or milimeter wave transmission systems lying along irregular paths. A paraxial ray theory of the system is given, as well as ewperimental results.

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DEGENERATE OPTICAL CAVITIES : III EFFECT OF ABERRATIONS

J. A. Arnaud

Applied Optics, vol. 9, Page 1192, may 1970

ABSTRACT

The capability of degenerate optical cavities to transmit faithfully incident optical signals with arbitrary wavefronts is limited primarily by geometrical optics aberrations. This capability is expressed by an acceptance factor which is calculated for various types of cavities lacking first-order degeneracy, or suffering from primary aberrations. It is found that the acceptance factors of spherically symmetric cavities are larger, by orders of magnitude, than the acceptance factors of cavities possessing only rotational symmetry (such as the well-known confocal cavity). The correction of primary aberrations for both types of cavities is discussed. Acceptance factors of the order of 107 with finesses of the order of 100 can be obtained. The mechanical accuracy required is, however, a few orders of magnitude higher than in conventional optical instruments.

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LASER AND OPTICAL RESONATORS WITH BEAM TWISTING

J. A. Arnaud

BREVET

5 août 1969

ABSTRACT

Optical resonateors and regenarative laser amplifiers are disclosed. In all cases, the resonateors are made fully degenerate, in order to be useful in processing multiple modes or amplifying images. Full degeneracy is accomplished with relatively few lenses by inverting any bundle of resonated rays at planar reflectors. The resonators typically employ one or more rooftop reflectors or corner reflectors arranged to provide ray inversion.

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