Showing papers in "Journal of Modern Optics in 1980"
TL;DR: In this article, a non-linear optical system with a mode coupled to its second harmonic, exhibiting a rich variety of non-equilibrium steady-state transitions is analyzed, and a semiclassical analysis is used to examine the steady states and their stability, and thus predict the existence of various instabilities.
Abstract: In this, the first of two papers on the subject, we present an analysis of a non-linear optical system with a mode coupled to its second harmonic, exhibiting a rich variety of non-equilibrium steady-state transitions. Here we use a semiclassical analysis to examine the steady states and their stability, and thus predict the existence of various instabilities. We find that this system exhibits both first- and second-order phase transition-like behaviour, as well as having a hard mode transition. The application of this system as a switching device is also considered.
245 citations
TL;DR: In this paper, the theory of the noise in optical fibres excited by partially coherent sources is presented, following the basic guidelines of the speckle theory, and it is shown that the noise can be modelled as a Gaussian distribution.
Abstract: Modal noise has been observed in optical fibres excited by partially coherent sources. In this paper the theory of this noise is presented. Following the basic guidelines of the speckle theory, the...
49 citations
TL;DR: In this paper, electric, optical and acoustic interactions in dielectrics are discussed. But they do not consider the effect of noise on the electrical properties of the dielectric components.
Abstract: (1980). Electric, Optic and Acoustic Interactions in Dielectrics. Optica Acta: International Journal of Optics: Vol. 27, No. 6, pp. 732-733.
46 citations
TL;DR: In this article, the maximum number of degrees of freedom which can be used without the fit becoming unstable due to ill-conditioning is considered and an effective model for fitting a whole range of photon correlation data is described.
Abstract: Effective models for fitting a whole range of photon-correlation data are described. They incorporate the maximum number of degrees of freedom which may be used without the fit becoming unstable due to ill-conditioning and lead to a computer program which is extremely fast and may readily be implemented on a minicomputer. The results of some preliminary calculations on laser anemometry and macromolecular polydispersity are presented.
44 citations
39 citations
39 citations
TL;DR: In this paper, it is shown that suitable superpositions of mutually uncorrelated spatially coherent contributions can drastically reduce the spatial coherence of the resulting field without affecting the far-zone intensity distribution.
Abstract: The same directionality properties as a laser field or, indeed, as any coherent field can be obtained with sources that are nearly spatially incoherent This has been proved by Collett and Wolf Here, it is shown that such a result can be made clear intuitively by realizing that suitable superpositions of mutually uncorrelated spatially coherent contributions can drastically reduce the spatial coherence of the resulting field without affecting the far-zone intensity distribution Practical methods for obtaining such superposition fields starting from spatially incoherent sources are discussed
39 citations
TL;DR: In this paper, it is shown that the Meecham-Yasuura numerical method is not a valid indicator of the possibilities of the Rayleigh theory and that the application of the Fourier method enables the theory of the latter to be used, with success, for attaining at least 0·35, regardless of the polarization.
Abstract: It is shown that the Meecham-Yasuura numerical method is not a valid indicator of the possibilities of the Rayleigh theory. In this way, Petit showed that the Rayleigh theory is useful only if the amplitude/period (h/d) ratio does not exceed approximately 0·144. Actually, the application of the Fourier method, proposed by Rayleigh himself, enables the theory of the latter to be used, with success, for h/d attaining at least 0·35, regardless of the polarization. This is demonstrated by comparisons with results obtained by other authors from rigorous integral equation methods.
35 citations
33 citations
TL;DR: In this article, the authors studied the scattering of electromagnetic waves by dielectric cylinders and, in particular, by optical fibres through integral equations and established the convergence of the iterations of the integral equations under certain conditions.
Abstract: The scattering of electromagnetic waves by dielectric cylinders and, in particular, by optical fibres is studied through integral equations. The convergence of the iterations of the integral equations is established under certain conditions. The latter are satisfied for long wavelengths, and for optical fibres and wavelengths, when the dielectric permeability variation is rather small. An approximate eikonal solution is applied to optical fibres, and its reliability is discussed. A systematic procedure for estimating corrections to the eikonal approximation is proposed.
33 citations
TL;DR: In this paper, the authors presented the Semiconductor Devices for Optical Communications (SDE) for optical communications, which is a family of semiconductor devices designed for optical communication.
Abstract: (1980). Semiconductor Devices for Optical Communications. Optica Acta: International Journal of Optics: Vol. 27, No. 10, pp. 1398-1399.
TL;DR: In this article, the nonlinear Optics of Free Atoms and Molecules (NOMA) of free atoms and molecules is discussed. But the authors do not discuss the relationship between the NOMA and free atoms.
Abstract: (1980). Nonlinear Optics of Free Atoms and Molecules. Optica Acta: International Journal of Optics: Vol. 27, No. 6, pp. 731-731.
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TL;DR: In this paper, the authors trace les courbes de birefringence d'ecoulement en fonction du debit en differents points du champ and pour different concentrations, mettant ainsi en evidence la necessite d'un gradient elongationnel minimum for obtenir le deploiement des macromolecules dissoutes.
Abstract: Dans certaines conditions, l'action d'un gradient elongationnel permet d'obtenir une deformation tres importante des macromolecules souples se traduisant par l'apparition de birefringence d'ecoulement tres localisee. On montre que des ecoulements, a l'arriere d'obstacles, peuvent produire de tels effets. Dans le cas d'un diedre a angle droit, on a trace les courbes de birefringence d'ecoulement en fonction du debit en differents points du champ et pour differentes concentrations, mettant ainsi en evidence la necessite d'un gradient elongationnel minimum pour obtenir le deploiement des macromolecules dissoutes. On note egalement la difference de comportement entre particules rigides et deformables.
TL;DR: In this article, the single interval statistics of an integrated gamma-distributed variable with lorentzian spectrum were derived directly from a rate equation for the process, as a special case, the integrated photon statistics predicted by a model for single-mode thermal radiation in a cavity.
Abstract: Intensity fluctuations arising from a random walk in 2α dimensions are governed by the gamma-distribution of parameter α. When 2α is fractional, conventional methods of calculating statistical properties of the integrated intensity, based on a gaussian noise theory approach, can no longer be used. In this paper the single interval statistics of an integrated gamma-distributed variable with lorentzian spectrum are derived directly from a rate equation for the process. The results include, as a special case, the integrated photon statistics predicted by a model for single-mode thermal radiation in a cavity.
TL;DR: In this article, an arrangement in which the beam in a microscope traverses the object more than once was proposed, which results in the image of a single point for two passes through the object being 2·4 times as sharp as that in a conventional microscope, the side lobes also being extremely small.
Abstract: An arrangement is proposed in which the beam in a microscope traverses the object more than once. This results in the image of a single point for two passes through the object being 2·4 times as sharp as that in a conventional microscope, the side lobes also being extremely small. In the microscope in which the beam passes through the object twice the image amplitude behaves similarly to the image intensity in a conventional partially coherent microscope. Theoretical images of various objects are calculated, and the effects of using annular lenses discussed.
TL;DR: In this article, the appearance of higher order diffracted modes for thick one-dimensional phase gratings is investigated and criteria, determining the significance of the higher modes, are discussed and their validity illustrated by means of computer calculations.
Abstract: The appearance of higher order diffracted modes is investigated for thick one-dimensional phase gratings. The criteria, determining the significance of the higher modes, are discussed and their validity illustrated by means of computer calculations.
TL;DR: In this article, different sets of coupled differential equations describing the steady-state fields inside the Fabry-Perot cavity are solved analytically within the framework of the theories of absorptive bistability.
Abstract: Within the framework of the theories of absorptive bistability recently proposed by various authors, the different sets of coupled differential equations describing the steady-state fields inside the Fabry-Perot cavity are solved analytically. Expressions are obtained for the bistability equation, which links the incident and transmitted fields, for different ranges of the mirror transmission coefficient. Comparison is made with the mean-field theory of Bonifacio and Lugiato. Conditions for stationary points in the bistability curve are derived.
TL;DR: In this paper, Raman spectra in the region of the OH stretching mode are studied in ZnBr 2 solutions, as a function of concentration, and it is shown that the spectra continuously change from that of pure water on that of the hydrated crystal.
Abstract: Raman spectra in the region of the OH stretching mode are studied in ZnBr 2 solutions, as a function of concentration. It is shown that the spectra continuously change from that of the pure water on that of the hydrated crystal. According to a new model, the spectra can be obtained as a suitable superposition of the latter. The meaning of such a superposition is discussed in terms of structural properties, and turns out to be consistent with previous results obtained by a wide variety of experimental techniques.
TL;DR: In this paper, the effects of the distortion on the peak intensity of a focal spot are evaluated by using the normalized intensity function i(P) as a performance figure, expanding the distorted mirror aberration function in a series of Zernike polynomials.
Abstract: The thermal deformation of a metallic mirror used for focusing on or simply directing a laser beam to a workpiece is investigated. The displacement of the front surface is evaluated by using a rapidly converging Dini series. The effects of the distortion on the peak intensity of a focal spot are evaluated by using the normalized intensity function i(P) as a performance figure. Expanding the distorted mirror aberration function in a series of Zernike polynomials, the dependence of i(P) on the mirror illumination and physical parameters is assessed. The results of many calculations illustrate the potential of this analysis.
TL;DR: In this paper, a new formulation of Miller's regularization theory is proposed for object restoration problems, which is particularly suitable for object recovery problems and can be used for precise valuations of the resolution attainable in a given problem.
Abstract: We propose a new formulation of Miller's regularization theory, which is particularly suitable for object restoration problems. By means of simple geometrical arguments, we obtain upper and lower bounds for the errors on regularized solutions. This leads to distinguish between ‘Holder continuity’ which is quite good for practical computations and ‘logarithmic continuity’ which is very poor. However, in the latter case, one can reconstruct local weighted averages of the solution. This procedure allows for precise valuations of the resolution attainable in a given problem. Numerical computations, made for object restoration beyond the diffraction limit in Fourier optics, show that, when logarithmic continuity holds, the resolution is practically independent of the data noise level.
TL;DR: In this paper, an analysis of photon correlation measurements for fluorescent light from a beam of two-level atoms is given where the number of pulse pairs n(τ) with time separation τ is recorded using a time-to-digital converter.
Abstract: An analysis of photon correlation measurements for fluorescent light from a beam of two-level atoms is given where the number of pulse pairs n(τ) with time separation τ is recorded using a time-to-digital converter. These measurements are shown to correspond precisely to a subsequently normalized second-order correlation function (i.e. the normalization is performed after time averaging).
TL;DR: In this article, the Optical Design of Reflectors (ODD) is discussed. But the focus is on the optical design of reflectors and not on the design of the reflector itself.
Abstract: (1980). The Optical Design of Reflectors. Optica Acta: International Journal of Optics: Vol. 27, No. 9, pp. 1305-1305.
TL;DR: In this article, light beating spectroscopy experiments were performed on concentrated W/O microemulsions located in the vicinity of the gel phase on the phase diagram, and the most interesting feature is the non-exponential behaviour of the self-correlation function g (1)(K, τ) of the scattered field.
Abstract: Light beating spectroscopy experiments were performed on concentrated W/O microemulsions located in the vicinity of the gel phase on the phase diagram New results are reported: the most interesting feature is the non-exponential behaviour of the self-correlation function g (1)(K, τ) of the scattered field The initial decay rate of g (1)(K, τ) is not directly proportional to K 2; whereas the long time decay is found fairly exponential
TL;DR: In this article, the dielectric slab is considered as a system of classical dipoles fixed on the lattice points of N + 1 parallel planes of a general primitive crystal lattice.
Abstract: The dielectric slab is considered as a system of classical dipoles fixed on the lattice points of N + 1 parallel planes of a general primitive crystal lattice. The dipoles interact with retarded electromagnetic and non-retarded mechanical forces. Thus media with spatial dispersion are also taken into account. Formulae are deduced for the intensity of the electromagnetic wave, reflected or transmitted by the dielectric slab. The resulting formulae are valid for all wavelengths where the dipole approximation is appropriate. Thus they include both the effects known in the dynamical theory of X-ray diffraction as well as Snell's law and Fresnel's formulae for visible light and the effects caused by spatial dispersion.
TL;DR: In this article, a Methode zur Absolutprufung optischer Flachen, bezuglich ihrer Abweichungen von einer idealen Kugel, wird im einzelnen beschrieben und experimentell erprobt.
Abstract: Eine Methode zur Absolutprufung optischer Flachen bezuglich ihrer Abweichungen von einer idealen Kugel, die in den letzten Jahren entwickelt wurde [9, 10], wird im einzelnen beschrieben und experimentell erprobt. Sie eignet sich zur genauen Messung von Spharizitatsnormalen. Von verschiedenen Paaren von Normalen mit unbekannten Spharizitatsabweichungen wurden Interferogramme in vier verschiedenen Positionen aufgenommen und im Computer, unter Anwendung von Fehlerausgleichsmethoden, ausgewertet. Der Computer liefert die Spharizitatsabweichungen der Normale in Form von Hohenlinien, perspektivischen Darstellungen und der mittleren quadratischen Deformation sowie Angaben uber die erreichte Genauigkeit. Die Fehler bei der Absolutbestimmung der Spharizitatsabweichungen betrugen im Mittel ±λ /200.
TL;DR: In this article, a quantum model of single-mode multi-photon laser, subharmonic with respect to the difference in energy between the two levels, is proposed on the assumption of a onephoton loss mechanism and stable solutions of the set of equations of motion for the mean values of the intensive, slowly-varying operators characterizing the system are obtained.
Abstract: A quantum model of single-mode multi-photon laser, subharmonic with respect to the difference in energy between the two levels, is proposed on the assumption of a one-photon loss mechanism. Stationary solutions of the set of equations of motion for the mean values of the intensive, slowly-varying operators characterizing the system are obtained. Their stability is analysed, proving the occurrence of a first-order phase transition and determining the existence condition for many-photon lasing.
TL;DR: The optical function of the deep symmetrical convexiclivate purecone fovea of deep-sea notosudids has been examined within the limits of geometrical optics, assuming, inter alia, that the full lens aperture is available for formation of foveal images and that the spherical aberration of the lens is negligible.
Abstract: The optical function of the deep symmetrical convexiclivate purecone fovea of deep-sea notosudids has been examined within the limits of geometrical optics, assuming, inter alia, that the full lens aperture is available for formation of foveal images, that the spherical aberration of the lens is negligible, and that the refractive index of the retina is slightly higher than that of the vitreous. Refraction at the vitreo-retinal boundary in the deep part of the fovea distorts a decentred image of a point source into an elongated spot, almost a double spot, while light from an extended source (residual daylight) will produce uneven illumination within the fovea, with a ring-shaped area of least illumination concentric with the foveal centre. It is suggested that the main optical function of the notosudid fovea is to break the camouflage of mesopelagic animals using small photophores for countershading. The theory implies the angular distribution of the photophore light to differ from that of the residual da...