Showing papers in "Journal of Modern Optics in 1978"
TL;DR: In this paper, Ellipsometry and Polarized Light are discussed in terms of polarized light and ellipsometry in the context of the International Journal of Optics (IJO).
Abstract: (1978). Ellipsometry and Polarized Light. Optica Acta: International Journal of Optics: Vol. 25, No. 3, pp. 270-271.
515 citations
TL;DR: In this article, the effect of partial coherence of both the source and the detector in a scanning microscope is investigated and the transfer function for the system is derived and various special cases discussed.
Abstract: The effect of partial coherence of both the source and the detector in a scanning microscope is investigated. The transfer function for the system is derived and various special cases discussed. If the effective source and effective detector are coherent and incoherent, respectively, the microscope (Type 1) is of the form of the scanning transmission electron microscope (STEM). If the effective source and the effective detector are both coherent, the microscope (Type 2) is of the form of the scanning acoustic microscope. Scanning optical microscopes of both these types may be constructed. The effect of using a Type 2 scanning microscope in dark-field is discussed. This arrangement has the advantage over the Type 1 dark-field microscope that imaging for weak contrast specimens may be made linear.
125 citations
TL;DR: In this paper, a method is described by which optical diffusing surfaces may be formed using photoresist materials and the distribution of surface heights in the surfaces has been determined using an interferometric method.
Abstract: A method is described by which optical diffusing surfaces may be formed using photoresist materials. These surfaces have a surface profile which is smoothly modulated and thus amenable to theoretical modelling. The distribution of surface heights in the surfaces has been determined using an interferometric method. Typical results are given, together with comparisons with both the expected (gamma function) and desired (gaussian) forms of distribution.
90 citations
TL;DR: In this article, a number of beam-splitter designs utilizing thin metal films are discussed, and it is shown that, using conventional techniques, the required phase difference can be readily achieved using, for example, combinations of gold, chromium and aluminium films.
Abstract: The measurement of displacement using a Michelson-type interferometer requires a beam-splitter coating that ideally produces two signals in phase quadrature. In this paper a number of beam-splitter designs utilizing thin metal films are discussed. Problems associated with film deposition and monitoring are considered, and it is shown that, using conventional techniques, the required phase difference can be readily achieved using, for example, combinations of gold, chromium and aluminium films.
54 citations
TL;DR: In this article, the equivalent index method is applied to the design of metal-dielectric thin-film optical coatings, provided some simple approximations are made, which can be treated in exactly the same way as all dielectric periods.
Abstract: This paper describes the application of the equivalent index method to the design of metal-dielectric thin-film optical coatings. It is shown that, provided some simple approximations are made, metal-dielectric periods can be treated in exactly the same way as all-dielectric periods. Illustrations of the application of the technique to the design of a range of types of coating are given.
40 citations
TL;DR: In this article, the recording and reconstruction characteristics of the thick hologram grating recorded in such a medium are described, taking into account of the absorption of the recording medium, and the profile of the grating is described and the influence of absorption upon the diffraction efficiency and the angular sensitivity for both the transmission and reflection holograms is calculated using a coupled wave theory.
Abstract: The light beam is attenuated inside the recording medium. The recording and reconstruction characteristics of the thick hologram grating recorded in such a medium are described, taking into account of the absorption of the recording medium. The profile of the hologram grating is described and the influence of the absorption upon the diffraction efficiency and the angular sensitivity for both the transmission and reflection holograms is calculated using a coupled wave theory. The calculated results are supported with the experimental data obtained with 649F and dichromated gelatin plates.
39 citations
TL;DR: In this paper, the amplitude of the first-order diffracted wave and the diffraction efficiency are calculated for sequentially superposed plane gratings that are stored in dielectric transmission volume holograms.
Abstract: Based on the theory of coupled waves the amplitude of the first-order diffracted wave and the diffraction efficiency is calculated for sequentially superposed plane gratings that are stored in dielectric transmission volume holograms. Using suitable approximations, both the Bragg-angle incidence and any deviations can be described. The grating interaction effects make it possible to couple the incident energy from one wave to another and to build up beam-couplers and splitters with certain coupling parameters. These coupling properties are adjustable in a definite manner by the recording process.
31 citations
26 citations
TL;DR: In this paper, the authors considered the dielectric slab as a system of classical dipoles fixed on the lattice points of N + 1 parallel planes of a simple cubic 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 simple cubic lattice. The dipoles interact with retarded electromagnetic and non-retarded mechanical forces. Thus the media with spatial dispersion are taken into account, too. The problem of reflection and transmission of light by this system is solved in two steps. First, the amplitudes of the dipole moments are evaluated as a function of the incident electromagnetic wave. Then the electromagnetic field generated by the vibrating dipoles of the entire slab is calculated. The resulting formulae for the angle of refraction and for the intensity of the reflected and transmitted waves coincide with the classical Snell law and Fresnel formulae, if the wavelength of the incident light is much greater than the lattice constant of the slab. A generalized proof of the Ewald extinction theorem valid for all wavelengths and for spatially dispersive media is given.
26 citations
TL;DR: In this paper, a new formalism for diffraction gratings consisting of a single grating surface surrounded by a number of planar films is presented, and the diffraction problem is shown to reduce to the solution of a Fredholm integral equation of the first kind.
Abstract: A new formalism for diffraction gratings consisting of a single grating surface surrounded by a number of planar films is presented. The diffraction problem is shown to reduce to the solution of a Fredholm integral equation of the first kind. The numerical implementation has been thoroughly tested using the constraints of energy conservation and reciprocity. A new constraint relating the phases and efficiencies of the propagating orders excited when a lossless symmetric transmission grating is operated in a first-order Littrow mount has been derived theoretically and verified numerically. The theory has been used to optimize the selective performance of a solar absorber consisting of a thin graphite layer deposited on a copper substrate. The superposition of a grating absorption feature on the primary resonance minimum of the absorptivity curve is shown to improve the integrated absorptivity by approximately 10 per cent.
26 citations
TL;DR: In this paper, the evolution of the polarization state of an elliptically polarized laser beam crossing a nonlinear medium is studied for a wide range of laser input powers surrounding the self-focusing or stimulated Raman threshold.
Abstract: The evolution of the polarization state of an elliptically polarized laser beam crossing a non-linear medium is studied for a wide range of laser input powers surrounding the self-focusing or stimulated Raman threshold. For powers inferior to that of the self-focusing threshold, the values of the real and imaginary parts of the xxyyx (y = y + y m y) component of the non-linear susceptibility tensor of several liquids are measured and the influence of two photon's absorption on the polarization state is studied. It is shown that for input powers near the self-focusing threshold, the ellipticity remains constant during self-focusing in the absence of non-linear absorption and diffusions. The influence of the stimulated Raman scattering on the polarization state of the exciting beam is observed for input powers larger than the Raman threshold.
TL;DR: In this article, image analysis and evaluation is used to evaluate the performance of image analysis in terms of image quality and image quality, and the results are presented in International Journal of Optics: Vol. 25, No. 11, pp. 1092-1092.
Abstract: (1978). Image Analysis and Evaluation. Optica Acta: International Journal of Optics: Vol. 25, No. 11, pp. 1092-1092.
TL;DR: In this paper, a photon correlation spectroscopy and Velocimetry method was proposed for image correlation spectrographs and it was shown that the method can be used for both image correlation and velocimetric analysis.
Abstract: (1978). Photon Correlation Spectroscopy and Velocimetry. Optica Acta: International Journal of Optics: Vol. 25, No. 3, pp. 271-272.
TL;DR: In this article, the authors compared the exact wave-equation solution results obtained by ray-optics and geometric optics for the dimensionless waveguide parameter V. Even when the effects of dispersion are included, the WKB condition gave exactly the same transit times as the more physically intuitive rayoptics technique.
Abstract: Transit times and eigenvalue equations found using ray-optics methods are compared with the exact wave-equation solution results. Geometric optics gives excellent accuracy for commonly used values of the dimensionless waveguide parameter V. Even when the effects of dispersion are included, the WKB condition gives exactly the same transit times as the more physically intuitive ray-optics technique.
TL;DR: In this paper, a theoretical analysis of two allied laser speckle interferometric techniques for measuring surface displacement and strain was carried out for the cases when a generalized deformation of the surface under study takes place.
Abstract: This article deals with a theoretical analysis of two allied laser speckle interferometric techniques for measuring surface displacement and strain. One technique uses a Double Aperture Speckle Camera, and the other uses a similar interferometer called a Double Aperture Speckle Shearing Camera. These techniques, although developed elsewhere, had not been analysed for the cases when a generalized deformation of the surface under study takes place. Such an analysis was done and is presented here in an abbreviated form. It results in ‘new’ equations governing the formation of fringes by the two cameras. Various solution methods of these equations are outlined and discussed.
TL;DR: The classical theory of first-order chromatic aberrations neglects terms of paraxial order in aperture and powers higher than the first in glass dispersions as discussed by the authors, leading to the erroneous conclusio...
Abstract: The classical theory of first-order chromatic aberrations neglects terms of paraxial order in aperture and powers higher than the first in glass dispersions. This has led to the erroneous conclusio...
TL;DR: The Elements of Wave Propagation in Random Media as mentioned in this paper is a seminal work in the field of wave propagation in random media, which is used in the present paper, as well.
Abstract: (1978). The Elements of Wave Propagation in Random Media. Optica Acta: International Journal of Optics: Vol. 25, No. 4, pp. 358-358.
TL;DR: In this article, a generalized long-baseline amplitude interferometer which operates in pupil space is examined, and the advantages of working in pupilspace are considered by comparison with image space methods.
Abstract: A generalized long-baseline amplitude interferometer which operates in pupil space is examined. The advantages of working in pupil space are considered by comparison with image space methods. In the absence of chromatic incoherence the pupil space interferometer gives immunity against guiding errors and arbitrarily good signal to noise ratios with arbitrarily large telescope pupils. Chromatic effects, when combined with random guiding errors, set an upper limit to the pupil size which may be used with a given bandwidth, but the pupil space design remains less sensitive to guiding errors than image space designs.
TL;DR: In this article, a self-addition process for complex optical signals is described without the aid of any optical accesories such as lenses or spatial filters, and the properties of periodic optical objects are used for coherently illuminating a suitable periodic object.
Abstract: In the present work addition or/and subtraction of complex optical signals is obtained without the aid of any optical accesories such as lenses or spatial filters In the self-addition process the properties of periodic optical objects are used The principle of self-addition involves coherently illuminating a suitable periodic object The object is composed of several various transmittances which represent the optical signals which are to be added The transmittances are grouped and periodically spaced in sets of mutually shifted sublattices of the compound object When the object is coherently transilluminated, then the images of the sum and difference of the transmittances appear in its diffraction light field The effect of forming multiple images, called compacted autoidolons, in the diffraction light field of periodic transmittances is here described and demonstrated experimentally
TL;DR: In this paper, the birefringence localisee se manifeste comme une ligne brillante extremement fine apparaissant quel que soit le sens de rotation des cylindres lorsque certaines conditions (de vitesse angulaire, de masse moleculaire, de viscosite, de geometrie, de deformabilite…) sont reunies.
Abstract: On etudie experimentalement la birefringence d'ecoulement apparaissant aux differents regimes de vitesses de rotation de deux cylindres d'axes paralleles places dans des solutions de macromolecules. Cette birefringence localisee se manifeste comme une ligne brillante extremement fine apparaissant quel que soit le sens de rotation des cylindres lorsque certaines conditions (de vitesse angulaire, de masse moleculaire, de viscosite, de geometrie, de deformabilite…) sont reunies. Cet effet pourrait s'expliquer par la presence d'un gradient elongationnel qui, outre une tendance a l'orientation, se traduirait par une deformation importante des macromolecules.
TL;DR: In this article, the theory of multilayer dielectric mirrors with residual absorptance is re-examined to determine whether lower absorptances and therefore higher reflectances can be achieved than with the usual type of alternating quarter-wave system.
Abstract: The theory of multilayer dielectric mirrors with residual absorptance is re-examined to determine whether lower absorptances and therefore higher reflectances can be achieved than with the usual type of alternating quarter-wave system. It is shown that considerable improvements are indeed possible if the layers of the material with high refractive index and residual absorption are made with optical thickness less than a quarter-wave, and the other layers with correspondingly greater optical thickness. Simple formulae are derived for the factor of improvement and the required optical thickness of the films of low refractive index. Moreover, by applications of the concept of potential transmittance and the principle of equivalent layers, a relationship is established between the desired limiting reflectance of the system and the necessary number of layers.
TL;DR: In this paper, the authors generalize a previous theory to study the phenomenon of absorption of plane waves by a grating working with several spectral orders, which allows predicting, with the aim of a simple formula, the shape of various kinds of grating anomalies.
Abstract: The authors generalize a previous theory to study the phenomenon of absorption of plane waves by a grating working with several spectral orders. The theory allows predicting, with the aim of a simple formula, the shape of various kinds of grating anomalies, as well as the shape of the total diffracted energy curve. The use of a convenient matrix, called S*S, leads to the introduction of the efficiency hyperellipsoid. This enables one to predict in a simple way a phenomenon of total absorption of a finite number of plane waves by a grating.
TL;DR: A hybrid image processing system with active feedback is capable of producing patterns that oscillate in space and time, and one goal is to study the generation of these fascinating picture oscillations.
Abstract: A hybrid image processing system with active feedback is capable of producing patterns that oscillate in space and time. The term ‘hybrid’ implies a combination of optical and TV-electronic components in our feedback system, where the TV camera looks at its own monitor. Some of the observed oscillating patterns are without precedence, especially if the imaging process from monitor to camera target is ‘non-congruent’. The term ‘non-congruent’ implies that the signal from a given point on the monitor will not return to its former place after passing through the loop. Image rotation and magnification mismatch are prominent examples of ‘non-congruent’ processes in that context. One goal is to study the generation of these fascinating picture oscillations. Another goal is to learn how to prevent these oscillations in situations where they are undesirable, as, for example, in transfer-function synthesis by active feedback.
TL;DR: In this article, an analysis of the contrast in speckle patterns produced by slightly rough diffusers is carried out without making use of the central limit theorem, and the results obtained explain an effect observed in previous experimental work.
Abstract: An analysis of the contrast in speckle patterns produced by slightly rough diffusers is carried out without making use of the central limit theorem. The results obtained explain an effect observed in previous experimental work. A comparison with the behaviour of the contrast predicted by a gaussian approximation is presented.
TL;DR: In this paper, a two-wavelength speckle-pattern interferometry technique was proposed to compare complex objects of nominally identical geometries, where the inspection object (usually of non-specular finish) is illuminated by a smooth master wavefront at wavelength u 1.
Abstract: This paper demonstrates that two-wavelength speckle-pattern interferometry may be used to compare complex objects of nominally identical geometries. The principle of the technique is that the inspection object (usually of non-specular finish) is illuminated by a smooth 'master wavefront' at wavelength u 1. The u 1 interferogram formed between the speckle image of this object and an in-line reference beam is then subtracted from the corresponding pattern observed at a second wavelength u2. (u2 m u1 is typically 10 nm.) Speckle pattern correlation fringes observed in the subtracted pattern define differences between the inspection object and master wavefront of magnitude Gu1u2/(u2 m u1), where G is a function of the object geometry. Master wavefronts of complex geometry are reconstructed by holographic elements which initially record the light field reflected from a specular master component. This field is reconstructed to form the required illumination wavefront by re-illuminating the hologram with a wavef...
TL;DR: In this article, different sources of scattered light from diffraction gratings are considered, together with Fraunhofer diffraction in the wings of the spectral line, and the conditions necessary for an unambiguous specification are listed.
Abstract: The different sources of scattered light from diffraction gratings are considered, together with Fraunhofer diffraction in the wings of the spectral line, and the conditions necessary for an unambiguous specification are listed. Measurements of scattered light made with a helium-neon laser are quoted for a number of gratings and comparisons are made between interference (holographic) and ruled gratings.
TL;DR: In this paper, a Gaussian quadrature-based program for the calculation of the optical transfer function (OTF) using symmetry considerations is described. But the program uses considerations of symmetry to save computer time, and several means of checking intermediate results are described.
Abstract: A program for the calculation of the optical transfer function, using Gaussian quadrature, is described. The program uses considerations of symmetry to save computer time, and several means of checking intermediate results are described. The program may be used to calculate either monochromatic or heterochromatic values of the OTF.
TL;DR: In this article, the authors examined the special difficulties associated with the application of optical inspection techniques to a dull metallic surface at line speeds of up to 50 ms m 1 and discussed some of the optical, mechanical and electronic constraints imposed by the inspection requirement.
Abstract: In collaboration with the British Steel Corporation, Sira Institute Ltd is currently pursuing the development of sophisticated equipment for the automatic inspection of cold rolled steel strip. This paper will examine the special difficulties associated with the application of optical inspection techniques to a dull metallic surface at line speeds of up to 50 ms m 1. The development work has centred on the use of high-speed scanned laser systems, unique in their ability to provide diffraction-limited resolution with intrinsically high optical throughput. In order to detect and delineate all significant defects down to the most subtle imperfections, the polar scattering characteristics of the surface have been exploited and optimum signal processing techniques are being identified. The paper will discuss some of the optical, mechanical and electronic constraints imposed by the inspection requirement.