Showing papers in "Journal of Optics in 1978"
TL;DR: In this article, a new theory is presented to study the diffraction and absorption of an electromagnetic wave by a two dimensional grating, in order to optimize the geometrical effects of absorbing surfaces.
Abstract: A new theory is presented to study the diffraction and absorption of an electromagnetic wave by a two dimensional grating, in order to optimize the geometrical effects of absorbing surfaces. A computer program is developed, and is verified using various tests.
57 citations
TL;DR: In this paper, the index profile of a dielectric layer backed by a perfectly conducting plane is analyzed in a rigorous manner and it is explained why the problem is ill posed in the sense of Hadamard (1932).
Abstract: An attempt is made to determine a diffracting object from a diffraction pattern. Specifically the index profile of a dielectric layer backed by a perfectly conducting plane is required. The mathematical difficulties are analysed in a rigorous manner and it is explained why the problem is 'ill posed' in the sense of Hadamard (1932). A weak error on the data can produce on extreme error on the object determination. To overcome this difficulty, recent work by Tikhonov (1976) was consulted. On several examples it is shown that the numerical program used permits the index profile to be determined without hypothesis of their shapes.
44 citations
TL;DR: In this article, it is shown that highly contrasted fringes can be obtained for any rotation angle, by cementing an appropriate phase plate to the entrance face of each roof-prism.
Abstract: The variation with rotation angle, of the fringe visibility at the output of a rotation shearing interferometer illuminated with unpolarised light, is investigated both theoretically and experimentally. It is shown that highly contrasted fringes can be obtained for any rotation angle, by cementing an appropriate phase plate to the entrance face of each roof-prism. Neither a polarizer nor an analyzer is necessary. The method can be applied to any interferometer using roof-prisms.
35 citations
TL;DR: In this article, a technique of spatial filtered pseudocolor holographic imaging is described, where the encoding process takes place at the spatial frequency plane together with the one-step rainbow holographic process.
Abstract: A technique of spatial filtered pseudocolor holographic imaging is described. The encoding process takes place at the spatial frequency plane together with the one-step rainbow holographic process. The pseudocolor hologram imaging is obtained by the white light reconstruction of the multiplexed rainbow hologram. This technique provides a simple encoding procedure and offers a wide range of pseudocolor holographic images. The potential applications of this pseudocolor holographic imaging can range from aerial photography for remote sensing to X-ray transparencies for medical diagnosis. Experimental setup of this pseudocolor encoding process is illustrated. Some experimental demonstrations of the pseudocolor encoding hologram images are also provided.
29 citations
TL;DR: The STEM arrangement and a generalization of it are discussed in some detail and some STEM analogues of psychography are proposed.
Abstract: Half-plane apertures in transmission electron microscopy (TEM) and split detectors in scanning transmission electron microscopy (STEM) can provide useful information about the phase and amplitude components of the specimen transparency. A procedure involving structured incident illumination (psychography) in TEM has so far proved difficult to apply in practice. The STEM arrangement and a generalization of it are discussed in some detail and some STEM analogues of psychography are proposed.
25 citations
TL;DR: In this paper, a numerical approach of the reconstruction of an inhomogeneous slab is described, the relative permittivity or the index of which are unknown, and a solution of this inverse problem is based upon a space-time discretization of a field integral formulation, in time domain.
Abstract: A numerical approach of the reconstruction of an inhomogeneous slab is described, the relative permittivity or the index of which are unknown. This one-dimensional dielectric medium is assumed to be linear, isotropic and non-magnetic, its conductivity being known, generally equal to zero. Its frequency independent permittivity arbitrarily varies, normally to its interfaces. A TEM plane wave of arbitrary causal time dependence illuminates this slab. A solution of this inverse problem is based upon a space-time discretization of a field integral formulation, in time-domain. A checked iterative process makes it possible to determine the index profile step by step. Some examples are given to illustrate the main features of this reconstruction method; simulation of experimental errors is considered with a special attention.
22 citations
TL;DR: In this paper, the optical transfer function (OTF) of a perfect lens with zonal masking of the lens aperture with polarisation devices has been studied and it is shown that the OTF of such system can be varied continuously by varying state of polarisation of the input beam and also by changing the orientation of the analyser placed at the output side.
Abstract: The optical transfer function (OTF) of a perfect lens with zonal masking of the lens aperture with polarisation devices has been studied. It is seen that the OTF of such system can be varied continuously by varying state of polarisation of the input beam and also by changing the orientation of the analyser placed at the output side.
21 citations
TL;DR: In this paper, the authors proposed four automation schemes with polarizing/analyzing optics that consist of rotating polarizer, depolarizer, rotating half-wave retarder and fixed polarizer.
Abstract: Photometric (autocollimation) return path ellipsometers (RPE) are described that operate at oblique and/or normal incidence for the examination of optically isotropic and anisotropic surfaces and thin films. Four automation schemes are proposed with polarizing/analyzing optics that consist of: 1) a rotating polarizer, 2) rotating polarizer and depolarizer, 3) rotating half-wave retarder and fixed polarizer, or 4) rotating polarizer and fixed polarizer. In all cases, it can be shown how the surface ellipsometric parameters ( psi and Delta ) can be retrieved from a photoelectric signal by simple Fourier analysis.
12 citations
TL;DR: In this article, the Fourier transform of the spectral distribution of energy from a source illuminating a double beam interferometer with transverse splitting by dividing luminance is used for spectral correlation.
Abstract: The general correlation principles for spectra and spectra derivatives are studied by using the Fourier transform of the spectral distribution of energy from a source illuminating a double beam interferometer with transverse splitting by dividing luminance. In this correlation technique, the use of such an interferometer has the advantage of greater luminosity as compared with a slit spectrometer. However, the correlation example indicates that it is necessary to adapt the correlator to the particular case considered, in order to obtain the best gain in the signal to noise ratio. In the case of sulfur dioxide detection, a very simple mounting which could be used in some interesting industrial applications was developed. This mounting can be used each time that the substance to be analyzed has a quasi-periodic absorption spectrum: in particular this is often the case with absorption spectra of gases, and a mounting identical to the one described for sulfur dioxide proved to be effective in the detection of nitrogen oxides.
12 citations
TL;DR: In this paper, a curve of growth method was used to determine the line strengths from spectra obtained by Fourier Spectrometry (FSA) for lines of H216O and H218O molecules.
Abstract: A method is proposed to determine line strengths from spectra obtained by Fourier Spectrometry. Details of the methods to deduce, from the spectrum, the data necessary to calculate the line strengths are given. The author has adapted the curve of growth method to deduce the line strengths from, either the equivalent widths, or the heights of the lines. Examples of application to lines of the H216O and H218O molecules are presented.
TL;DR: In this paper, a theoretical study of the diffraction of a plane Gaussian wave truncated by annular aperture has been performed, where Kirchhoff's integral has been evaluated to obtain the irradiance distribution in the diffracted field.
Abstract: A theoretical study of the diffraction of a plane Gaussian wave truncated by annular aperture. Kirchhoff's integral has been evaluated to obtain the irradiance distribution in the diffracted field. Results of the calculations conducted for optimum size of the annular aperture for various values of the Gaussian spot size have been presented graphically.
TL;DR: In this paper, the displacement of a light ray at a dielectric-vacuum interface is studied by means of Fermat's principle, and it is shown that given any two points in the denser medium, there might be two, one, or no way of joining them by the light ray, according to the geometry.
Abstract: The reflection of a light ray at a dielectric-vacuum interface is studied by means of Fermat's principle. Allowing for propagation in the rarer medium in the form of evanescent waves and using for these waves the group velocity previously derived by one of the authors, one obtains the displacement of the reflected ray known as the Goos and Hanchen effect (1949). The expression for the displacement arrived at in this way coincides with that derived by other methods by Artmann (1949) Fragstein (1949) and more recently by Agudin (1968). It is shown further that given any two points in the denser medium, there might be two, one, or no way of joining them by a light ray, according to the geometry.
TL;DR: In this paper, color images are stored on black and white film and three fundamental components are extracted by means of color filters, each component in turn is placed in contact with a grid, and in the Fourier plane, a mask selects two diffracted orders.
Abstract: Color images are stored on black and white film. Three fundamental components are extracted by means of color filters. Each component in turn is placed in contact with a grid, and in the Fourier plane, a mask selects two diffracted orders. Thus in the image plane each component modulates a different spatial carrier. The plate on which the three components are recorded diffracts as three superposed sinusoidal gratings, and the color image is retrieved by placing a demodulating mask-with appropriate color filters-in the Fourier plane of the plate. Considerations are given concerning the quality of the retrieved image, in particular the color fidelity.
TL;DR: In this paper, one-dimensional autocorrelation functions for the angle-of-arrival fluctuations are estimated in real time using a linear photodiode array and a numerical correlator.
Abstract: One-dimensional autocorrelation functions for the angle-of-arrival fluctuations are estimated in real time using a linear photodiode array and a numerical correlator. The results are found to be in agreement with the inertial model of turbulence for spatial shifts up to 25 cm in daytime conditions and up to 1.10 m in nighttime conditions. The Fried's seeing parameter r0 and the integral integral CN2dh of the structure constant CN2 for the fluctuations of the refractive index of the air are evaluated over the lower atmosphere. Crosscorrelation function estimations allow localisation of atmospheric turbulence. For the observations performed in daytime, a simple CN2-profile model assuming a strong turbulence in the telescope dome and a much weaker turbulence along the sight line in free atmosphere gives a reasonable account of the experimental results. For nighttime observations, a noticeable turbulence is detected at altitudes higher than approximately 500 m while turbulence in the dome is relatively weak.
TL;DR: In this paper, the method of moments is used to investigate the diffraction properties of a doubly periodic grating whose mutually orthogonal axes of periodicity lie in separated planes.
Abstract: The method of moments is used to investigate the diffraction properties of a doubly periodic grating whose mutually orthogonal axes of periodicity lie in separated planes. A new constraint relating the electric field amplitudes in a Littrow mount has been discovered. This relation has been shown to be valid for any symmetric biperiodic grid. Numerical studies using the formalism have shown the structure to be capable of providing a/e ratios of the order of 30 and thus to be potentially useful in solar selective systems.
TL;DR: In this article, the edge effect in thermoplastic-photoconductor media has been studied and it was found that edge effect is in proportion to both the light intensity and the spatial frequency of the holograms, and is more remarkable in the PLA method than the conventional simultaneous method.
Abstract: An edge effect in thermoplastic-photoconductor media has been studied and it is found that the edge effect is in proportion to both the light intensity and the spatial frequency of the (holograms, and is more remarkable in the PLA method than the conventional simultaneous method. These results suggest that the edge effect is caused by the electric field which is bent by the uneven surface charges, the trapped charges and the localized charges in the photoconductor medium.
TL;DR: In this article, the process of speckle averaging in the imaging step in sub-channel holography has been studied experimentally, and the calculated probability density functions and the values of specckle contrast have been presented.
Abstract: The process of speckle averaging in the imaging step in Sub-channel holography has been studied experimentally. First order statistics of the recorded speckle patterns have also been considered and the calculated probability density functions and the values of speckle contrast have been presented. Good agreement between the experimental speckle patterns and the first order statistics is found to exist. A model analysis of the integrated speckle pattern is given in which the randomness introduced by the photographic recording has been considered ia terms of a ‘screen’ function.
TL;DR: In this article, it was shown that the photographic recording of two radially shifted speckle patterns displays, when illuminated by a parallel beam of laser light, interference rings, real on the one hand and virtual on the other hand.
Abstract: It is shown that the photographic recording of two radially shifted speckle patterns displays, when illuminated by a parallel beam of laser light, interference rings, real on the one hand and virtual on the other hand. The radii of the rings are in arithmetical progression and the sets of rings of radius r0 are generated by an annular area of the plate of mean radius r0/2. Each of the rings is localized in a particular plane and there are only two planes symmetrical with respect to H in which it is possible to observe a limited number of rings with maximum contrast.
TL;DR: Experimental results show the variation with wavelength of the location of this maximum efficiency point, regarded as the effective center of the pupil, and its interpreted with regard to a few specific aspects of color localization.
Abstract: After a short review of studies made on the Stiles-Crawford effect I and its relation to wavelength, the author concentrates more specifically on the location and significance of the Stiles-Crawford function peak. This is followed by experimental results which show the variation with wavelength of the location of this maximum efficiency point, regarded as the effective center of the pupil. For three wavelengths (blue lambda =470 nm, green lambda =536 nm, red lambda =653 nm), and seven observers representing both forms of color stereoscopy, a peak shift is revealed with regard to the pupil's geometric center (C). This shift varies from one subject to the next, and is different for each eye in the same subject. After analyzing the optical and dynamic factors of this variation, it is interpreted with regard to a few specific aspects of color localization (horopter and stereoscopy).
TL;DR: In this paper, the reflection and the refraction of plane uniformly heterogeneous waves on a plane boundary between two homogeneous isotropic and inactive medium are governed by generalized Snell's law.
Abstract: The reflection and the refraction of plane uniformly heterogeneous waves on a plane boundary between two homogeneous isotropic and inactive medium are governed by generalized Snell's law. If the equiamplitudes are perpendicular to the plane of incidence, the transmitted, and reflected waves are transverse if the incident wave is also. The energetic balance is established in the case of a transparent incident medium. The sum of reflectivity and transmissivity factors can differ from one. This result specifical to heterogeneous waves is analysed. Simple cases where an energetic flow goes from the second medium to the first are discussed.
TL;DR: In this paper, the state-of-the-art of computer generated holography (CGH) can be found in various coding schemes to record both the amplitude and phase of the field at the hologram plane.
Abstract: The article reviews the state of art of the computer generated holography. Sec. 2 deals with the various coding schemes to record both the amplitude and phase of the field at the hologram plane. Special emphasis is given to those coding schemes which are used for the generation of binary holograms. The theory of discrete Fourier transform (DFT) hologram and its optical reconstruction are treated in Sec. 3. The introdution of randomizer in front of the object while computing the D.F.T. and its influence on the reconstructed image have been discussed. Sec. 4 contains some of the major applications of the computer generated holograms (CGH). For examples, the generation of filters for coherent optical processing, fabrication of CGH’s for testing unconventional optics and GGH’s as generalised optical elements etc. have been discussed in detail.
TL;DR: In this article, a complex spinor satisfying the spinor Helmholtz equation was used to prove the reciprocity theorem in free space and average reciprocity in a weakly turbulent medium.
Abstract: At the Fresnel approximation, a polarized laser beam can be described by a complex spinor satisfying the spinor Helmholtz equation. This spinor formulation makes easy in free space the proof of the reciprocity theorem while an average reciprocity theorem is proved in a weakly turbulent medium.
TL;DR: Compared with an equidistant-ruled classical grating, a holographic grating offers four supplementary geometrical parameters, which gives a better mounting with improved stigmatism, and allows the formulation of satisfactory solutions for non-classical mountings.
Abstract: Compared with an equidistant-ruled classical grating a holographic grating offers four supplementary geometrical parameters, which gives a better mounting with improved stigmatism, and allows the formulation of satisfactory solutions for non-classical mountings. The author gives as an example such a calculation for the 'Nebular Spectrograph' designed for the Very Wide Field Camera (VWFC).
TL;DR: In this paper, the first and second order spectrograph mount efficiencies of triangular and sinusoidal groove gratings were examined theoretically and it was shown that near Littrow mountings yield optimum performance.
Abstract: The first and second order spectrograph mount efficiencies of triangular and sinusoidal groove gratings are examined theoretically. It is shown that near Littrow mountings yield optimum performance.
TL;DR: In this article, a basic relation presented in a previous paper is more generally demonstrated and thus can be extended to interfaces other than plane ones, e.g. cylindrical or spherical.
Abstract: A basic relation presented in a previous paper (see ibid., vol.8, p.127 (1977)) is more generally demonstrated and thus can be extended to interfaces other than plane ones, e.g. cylindrical or spherical. Some corrections to be made are given and one of the last equations is discussed again.
TL;DR: The behavior of the charge carriers in the thermoplastic-photoconductor system has been studied by the measurement of the diffraction efficiency instead of the usual current measurement, and the followings are found.
Abstract: The behavior of the charge carriers in the thermoplastic-photoconductor system has been studied by the measurement of the diffraction efficiency instead of the usual current measurement, and the followings are found. (1) The charge carriers are injected from the transparent conductor to the photoconductor and the minus charge injection depth is estimated to 0.1 mu m for 1:10 TNF:PVK complex and 0.3 mu m for 4:10 TNF:PVK complex. (2) A kind of rectification effect is analogous to that of the p-type semiconductor-metal system exists at the photoconductor transparent conductor interface.
TL;DR: In this paper, the authors compared the two-step imaging techniques of holography and radio astronomy aperture synthesis and concluded that coherent optical reconstruction of radio data as an alternative to digital reconstruction is possible.
Abstract: The strong parallels which exist between the two-step imaging techniques of holography and radio astronomy aperture synthesis suggest coherent optical reconstruction of radio data as an alternative to digital reconstruction. The holographic approach is described and some of its advantages and disadvantages are assessed. Data from the Westerbork aperture synthesis array are optically reconstructed.
TL;DR: In this paper, an unidimensional correlation function is computed whether applying the definition of these functions, or using a fast Fourier transform algorithm and He Wiener-Kinchine theorem.
Abstract: Numerical unidimensional correlation functions are computed whether applying the definition of these functions, or using a fast Fourier transform algorithm and He Wiener-Kinchine theorem. The processed signals have positive mean values; estimation problems of these mean values are considered when a finite number of samples are provided. An intercorrelation function estimation is examined; its bias is computed and its variance estimated in an approximated way. Thus it is shown that estimation errors could be important when shifts appearing in correlation functions computation are large.
TL;DR: In this article, the trajectories of the reflected and transmitted beams in the oblique tunnel effect in optics are studied and it is shown that both beams are parallel displaced away from their commonly accepted geometrical trajectories.
Abstract: The trajectories of the reflected and transmitted beams in the oblique tunnel effect in optics are studied. It is shown that both beams are parallel displaced away from their commonly accepted geometrical trajectories. When the gap tends to infinite, one obtains the ordinary Goos and Hanchen effect. When the gap goes from infinite to zero, the maximum in the parallel displacements of the reflected and transmitted beams is transferred from critical incidence to grazing incidence. The effect is polarization dependent, so that in the general case of random polarization there will be a splitting of both the transmitted and reflected beams.