Showing papers in "Journal of Modern Optics in 1973"
91 citations
TL;DR: Counterfeiting of valuable papers and identification documents made of paper or plastics, such as banknotes, credit cards, passports, etc., is presently inhibited through the use of inks of many colours, intricate engraved designs on special papers which sometimes contain watermarks or embedded coloured paper platelets or metal threads.
Abstract: Counterfeiting of valuable papers and identification documents made of paper or plastics, such as banknotes, credit cards, passports, etc., is presently inhibited through the use of inks of many colours, intricate engraved designs on special papers which sometimes contain watermarks or embedded coloured paper platelets or metal threads. These methods have not always offered adequate protection. It is proposed to use optical multilayer coatings to validate such documents. One property of such coatings is that their spectral characteristics vary with the angle of incidence of the light. For most applications this variation is a decided disadvantage and efforts are often made to minimize it. But by this property optical multilayers differ essentially from all known types of dyes, inks, pigments and paints used in printing, photography and colour-copying machines. This angular variation can be made use of to enable the man in the street to distinguish at a glance an authentic document bearing such a coating f...
81 citations
TL;DR: In this paper, Fourier transform and their physical applications are discussed in the context of Optica Acta and International Journal of Optics: Vol. 20, No. 11, pp. 915-915.
Abstract: (1973). Fourier Transforms and Their Physical Applications. Optica Acta: International Journal of Optics: Vol. 20, No. 11, pp. 915-915.
60 citations
TL;DR: In this article, an exact analytical formula for the flux density (energy per unit area per unit time) over an arbitrary receiver surface for rays which have been reflected from or refracted through an arbitrary curved surface is derived.
Abstract: An exact, analytical formula for the flux density (energy per unit area per unit time) over an arbitrary receiver surface for rays which have been reflected from or refracted through an arbitrary curved surface is derived. The change in flux density is associated with the geometrical concentration or spreading of the beam produced by the curvature of the deflecting surface. The formula is expressed in terms of the intrinsic geometry of the deflecting surface (Gaussian curvature, mean curvature, and normal curvature). An equation for the caustic surface is also derived. The general formulas are applied to calculate the flux density on an image plane when light from a point source is reflected from and refracted into a spherical surface. Equations are also given for the associated caustic surfaces. These yield, for paraxial rays, the standard mirror and lens formulas.
58 citations
49 citations
TL;DR: In this article, the first-order probability density function of laser speckle patterns observed through finite size apertures is theoretically studied, and an exact solution is obtained through the use of a two-dimens...
Abstract: The first-order probability density function of laser speckle patterns observed through finite size apertures is theoretically studied. An exact solution is obtained through the use of a two-dimens...
48 citations
TL;DR: In this article, a new technique of superresolution which makes use of a multi-exposed image hologram is described, where the basic idea is to use the hologram as storage medium for complex amplitude of the image of an object to be superresolved and to add up the complex amplitudes of the images of different spatial frequency ranges.
Abstract: A new technique of superresolution which makes use of a multi-exposed image hologram is described. The basic idea of this method is to use the hologram as storage medium for complex amplitude of the image of an object to be superresolved and to add up the complex amplitudes of the images of different spatial frequency ranges by multiple exposure on the hologram to synthesize the superresolved image. In this paper, a detailed analysis of the theory of this method, and the results of experiments for one-dimensional and two-dimensional objects, are presented. As a whole, the bandwidth of the optical system could be extended to the theoretically expected value.
29 citations
27 citations
TL;DR: In this paper, the authors described the extraction of design data for the low-pass dielectric multilayer according to Tschebysheff performance by analogy with electric-circuit design, and can then be given numerical refinement which is also described.
Abstract: The extraction of design data for the lowpass dielectric multilayer according to Tschebysheff performance is described. The extraction proceeds initially by analogy with electric-circuit design, and can then be given numerical refinement which is also described. Agreement with the Tschebysheff desideratum is satisfactory. The multilayers extracted by this procedure are of fractional thickness, symmetric with regard to their central layers.
27 citations
TL;DR: In this article, the authors presented advances in Electronics and Electron Physics (e.g., advances in electronics and electron physics) with the aim of improving the performance of their experiments.
Abstract: (1973). Advances in Electronics and Electron Physics. Optica Acta: International Journal of Optics: Vol. 20, No. 9, pp. 746-747.
TL;DR: Several factors associated with the high linear velocity of the emitters contribute to linewidths in the spectra of fast ion beams, such as broadening associated with acceptance angles determined by the spectrometer's collimator and slit, diffraction at the entrance slit, decollimation due to scattering and external fields, and the limited time during which an ion can emit into the Spectrometer as mentioned in this paper.
Abstract: Several factors associated with the high linear velocity of the emitters contribute to linewidths in the spectra of fast ion beams. These include broadening associated with the acceptance angles determined by the spectrometer's collimator and slit, diffraction at the entrance slit, decollimation due to scattering and external fields, and the limited time during which an ion can emit into the spectrometer. We discuss the observations of the known effects and those likely to appear, and consider methods for reducing them.
TL;DR: In this article, a simulation par le calcul sur ordinateur permet de montrer que l'influence des erreurs de realisation de chaque couche, sur le resultat final, depend du procede de controle utilise.
Abstract: Pour controler la formation de couches d'epaisseurs optiques ne egales ou multiples d'une meme valeur u0/4, on utilise couramment des methodes optiques. Il est en particulier commode de reperer, au cours de l'evaporation, pour la longueur d'onde de centrage du filtre u0, les extremums du facteur de transmission T. Mais on doit bien distinguer les extremums correspondant a T/ e=0 des extremums du profil spectral (T/u=0) observables pendant le depot de chaque couche. La simulation par le calcul sur ordinateur permet de montrer que l'influence des erreurs de realisation de chaque couche, sur le resultat final, depend du procede de controle utilise. Le reperage des zeros de T/u ne permet pas de beneficier d'une compensation des erreurs aussi exceptionnelle que celui des zeros de T/e. On souligne ainsi l'interet du choix d'un controle ‘stable’ ou l'influence des erreurs cumulatives est telle que leurs effets se compensent parfaitement. Les tolerances de realisation des filtres interferentiels sont alor...
TL;DR: In this paper, values provided by three different theories of the diffraction by gratings are compared with measurements made at millimetre wavelengths, based on the integral equation method of Pavage.
Abstract: Values provided by three different theories of the diffraction by gratings are compared with measurements made at millimetre wavelengths. The results based on the integral equation method of Pavage...
TL;DR: In this paper, the irradiance probability distribution for the phase structure function having a quadratic form and for the wave beam having a circular or elliptical cross-section was analyzed for a few typical cases.
Abstract: The irradiance probability distribution is analytically derived for the phase structure function having a quadratic form and for the wave beam having a circular or elliptical cross-section, and is illustrated for a few typical cases. When the relevant parameter E, representing the magnitude of wave fluctuation, has sufficiently small values in the range of E 1, the irradiance distribution can be close to the log-normal distribution. When E d 1, on the other hand, it gives rise to the so-called spot-dancing, and the log-irradiance is uniformly distributed in the important range of values of interest. The saturation phenomenon is also investigated for both irradiance and log-irradiance scintillations; it is found that the normalized variance of the irradiance scintillation shows a clear saturation in a wide range of the parameter E, although the variance ultimately does not tend to a finite value as E M X. On the other hand, the variance of the log-irradiance does not show any saturation.
TL;DR: In this article, the authors describe a new method of optical processing which is one of the principal topics of study in our laboratory, which consists of the detection of the difference between two images, the multiplexing of images, contrast reversal of the reconstructed images in carrier frequency photography, the coding and decoding of a message and the reconstruction of colour images from black and white recordings.
Abstract: In this article we describe a new method of optical processing which is one of the principal topics of study in our laboratory. This consists of the detection of the difference between two images, the multiplexing of images, the contrast reversal of the reconstructed images in carrier frequency photography, the coding and decoding of a message and the reconstruction of colour images from black and white recordings. The signal, modulated by a random diffuser with high spatial frequencies, is recorded at least twice on the same photographic plate with a small displacement of the plate between the exposures. The required information can be extracted by spatial filtering of the spectrum of the recorded signals. This spectrum is modulated by a system of interference fringes which determines the nature of the filter. The recording can be done in white light whereas the reconstruction is made in the laboratory using coherent light.
TL;DR: In this article, a phenomenological approach for the observation of non-linear magneto-optical effects such as frequency mixing of laser beams and optical harmonics generation in the presence of a d.c. magnetic field, as well as nonlinear magnetoroptical birefringence and rotation at Faraday or Voigt configurations, is discussed.
Abstract: Possibilities for the observation, in crystals and liquids, of new non-linear magneto-optical effects such as frequency mixing of laser beams and optical harmonics generation in the presence of a d.c. magnetic field, as well as non-linear magneto-optical birefringence and rotation at Faraday or Voigt configurations, are discussed in a phenomenological approach. The processes are described by axial non-linear magneto-electric susceptibility tensors Xijkl eeem and Xijkln eeeem, whose non-zero and independent elements are calculated by group theoretical methods for all crystallographical classes.
TL;DR: In this paper, a method is described, using exact ray-tracing, for calculating the wavefront aberration which arises from a change in geometry or wavelength between the recording and reconstructing processes, of a holographic image point, in the case of a plane hologram.
Abstract: A method is described, using exact ray-tracing, for calculating the wavefront aberration which arises from a change in geometry or wavelength between the recording and reconstructing processes, of a holographic image point, in the case of a plane hologram. The wavefront aberration value is needed to assess the image quality of a holographic system possessing magnification. In the present treatment a single hologram has been considered, but if necessary simple transfer formulae could extend this treatment to a multihologram system. Values of the wavefront aberration obtained from the theoretical calculation have been compared with experimental results and good agreement has been found.
TL;DR: The problem of determining the form of the triangular profile for a diffraction grating which gives high efficiency over the widest possible spectral region is investigated theoretically, for a large range of grating periods as mentioned in this paper.
Abstract: The problem of determining the form of the triangular profile for a diffraction grating which gives high efficiency over the widest possible spectral region is investigated theoretically, for a large range of grating periods. It is shown that rectangular profiles are generally to be preferred to those having higher apex angles (as suggested by Stroke [2]). A theoretical demonstration is given of an experimental result concerning the wavelength shift due to polarization, and a new phenomenon linking efficiency maxima and Wood anomalies is described.
TL;DR: In this article, two separate approaches have been put forward to account for the moire pattern produced by two overlapping zone plates, and the analysis has then been extended to include the case of three overlapping zone plate.
Abstract: Two separate approaches have been put forward to account for the moire pattern produced by two overlapping zone plates. The analysis has then been extended to include the case of three overlapping zone plates. Several new relationships regarding the formation of the moire pattern have been deduced and these are expected to find a more general application, particularly in the interpretation of images formed in the field-ion microscope.
TL;DR: In this article, simple expressions for the transmittance and absorptance of all-dielectric filters in terms of the width of their passband are derived. But these expressions are not applicable to weakly absorbing layers.
Abstract: The general expression for the potential transmittance of a layer, first derived by Berning and Turner [1], is simplified by the use of approximations applicable to weakly absorbing layers, and then used to describe the optical performance of mirrors and narrow-band filters consisting of such layers. In particular, simple expressions are obtained for the transmittance and absorptance of all-dielectric filters in terms of the width of their passband. These provide useful guides to the design of filters with minimum reduction of transmittance due to absorption in the layers, and also allow the absorptance and scattering contributions to be separated in measurements of the total loss.
TL;DR: In this paper, a Verfahren beschrieben, with dem die Abweichungen zweier unbekannter Testflachen von einer Referenzkugel bestimmt werden konnen.
Abstract: Es wird ein Verfahren beschrieben, mit dem die Abweichungen zweier unbekannter Testflachen von einer Referenzkugel bestimmt werden konnen. Auser den zu bestimmenden Testflachen befinden sich, im Gegensatz z.B. zu Shearing-Verfahren, keine optischen Elemente im Interferenzstrahlengang. Es braucht nur bei geringen Gangunterschieden gearbeitet zu werden, wobei Vielstrahlinterferenzen verwendet werden konnen. Minimal werden 3 Interferenzbilder benotigt, in denen sich die beiden Testflachen in verschiedenen Positionen relativ zueinander befinden (die Interferenzbilder konnen z.B. fotografiert oder abgetastet werden). Man erhalt die Abweichungen jeder Testflache von ihrer Referenzkugel in einem Ensemble von Mespunkten, die die Kugelflache in beiden Dimensionen besetzen.
TL;DR: In this article, the authors considered the process of the generation of stimulated Mandel'stam-Brillouin radiation and of stimulated Raman radiation in the laser itself at an arbitrary number of components generated for the case where only one axial mode in each component is excited.
Abstract: In this paper we consider the process of the generation of stimulated Mandel'stam-Brillouin radiation and of stimulated Raman radiation in the laser itself at an arbitrary number of components generated for the case where only one axial mode in each component is excited. The expressions for the steady-state radiation intensities of all the components generated versus the speed of active particle excitation in laser material, as well as the expressions for threshold values of this speed necessary to generate a given number of components, have been obtained. The conditions of possible effective conversion of laser light into radiation of stimulated scattering components have been cleared out. The feasibility of producing super-short light pulses due to synchronization of stimulated Mandel'stam-Brillouin radiation components by introducing a non-linear absorber into a resonator has been established.
TL;DR: In this article, the amplitude and phase variations across the reconstructed wavefront of a thick transmission hologram were derived for the purpose of describing the field variations in the region of the Gaussian image point or alternatively.
Abstract: Expressions are derived for the amplitude and phase variations across the reconstructed wavefront of a thick transmission hologram. The expressions can be used to describe the field variations in the region of the Gaussian image point or, alternatively. to describe the wavefront as it emerges from the hologram surface. Comparison with the ideal, Gaussian ‘reference’ sphere centred on the image point allows a pupil function to be defined. This differs from the pupil function of lens aberration theory in that it possesses spatial amplitude variations, as well as phase variations. Some predictions of the theory are illustrated by graphical examples. Experimental results are given.
TL;DR: In this article, the results of the computation of 26 higher-order modes of a Fabry-Perot resonator were presented, having a Fresnel number N = 12·25.
Abstract: The results are described of the computation of 26 modes of a Fabry-Perot resonator, having a Fresnel number N = 12·25. A comparison is also presented between these modes and those derived from the approximate theory of Wainstein. A first part of the paper is devoted to the description of the procedure used for the evaluation of higher-order modes. This general procedure is based on the orthogonality of the modes and can be applied to resonators of any shape. An analysis is also made of the influence, on the m th mode, of the unaccuracy by which the preceding m m 1 modes are computed.
TL;DR: In this article, the effects of absorption on the theoretical accuracy of the turning value method of film thickness monitoring in the production of thin-film all-dielectric narrow band optical filters are investigated.
Abstract: The effects of absorption on the theoretical accuracy of the turning value method of film thickness monitoring in the production of thin-film all-dielectric narrow band optical filters are investigated. It is shown that the performance of the method is at least as good as it is in the absence of absorption, although care must be taken in the interpretation of the monitoring signals for certain critical layers.
TL;DR: The lag of accommodation and the transfer function of accommodation computed from the response to a sudden shift in target distance were measured with the apparatus.
Abstract: An apparatus is described that automatically measures the course of the accommodation of the human eye with infra-red light. The principle of measurement is based on the spreading of the image of a test target on the retina when the eye is defocused. The measuring technique is an autocollimating one. Each single measurement tests the state of accommodation over a range from −7 to +2 D. Targets with a complicated structure such as gratings can be used to get a better criterion for defocusing. The apparatus gives 50 measurements of accommodation per second. Compared to the slow changes of accommodation this is an effectively continuous registration. The lag of accommodation and the transfer function of accommodation computed from the response to a sudden shift in target distance were measured with the apparatus.
TL;DR: The Remote Sensing of Earth Resources and the Environment-Proceedings of the S.I.P.E. as discussed by the authors, Vol. 20, No. 7, pp. 583-584.
Abstract: (1973). Remote Sensing of Earth Resources and the Environment-Proceedings of the S.P.I.E. Optica Acta: International Journal of Optics: Vol. 20, No. 7, pp. 583-584.
TL;DR: In this paper, a generalization of the plate diagram is given which permits the calculation of the aberrations of off-axis systems, taking into account anamorphosis due to the grating.
Abstract: A generalization of the plate diagram is given which permits the calculation of the aberrations of off-axis systems, taking into account anamorphosis due to the grating. It is preferable to work with the deformations of the wavefront rather than Seidel coefficients because in this way anamorphosis can be treated in a simple form. As examples, the aberrations of the Ebert and the Czerny-Turner spectrographs are calculated.