Showing papers in "Journal of Modern Optics in 1957"
TL;DR: A simple but accurate method of measuring the Depth of field of the eye is described and evidence that the retinal direction effect modifies depth of field has been obtained by measurement with fields of different colour but similar luminance.
Abstract: 1. A simple but accurate method of measuring the depth of field of the eye is described. 2. At a fixed pupil size the hyperfocal distance was found to increase directly with the log of the background luminance. 3. If the retinal illumination is held constant and the pupil size is altered, the depth of field varies approximately inversely with the pupil diameter. With pupil diameters greater than 2.5 mm the observed deviation from theoretical expectation can be accounted for by the operation of the retinal direction effect of Stiles and Crawford. 4. Further evidence that the retinal direction effect modifies depth of field has been obtained by measurement with fields of different colour but similar luminance. 5. The correction of chromatic aberration in the eye by means of an achromatizing lens decreases depth of field. 6. The minimum estimate for depth of field obtained under optimum conditions was ± 0.3 D at a pupil diameter of 3 mm. 1. Description d'une methode simple mais exacte permettant de measurer ...
343 citations
74 citations
TL;DR: The subjective disappearance of peripherally fixated objects has usually been regarded merely as an obstacle to satisfactory observation as discussed by the authors, however, the subjective image vanishing outside the paracentral region has been found to be characteristic of both rod and cone units.
Abstract: The subjective disappearance of peripherally fixated objects has usually been regarded merely as an obstacle to satisfactory observation. The course of local adaptation of a stimulus subtending 40 × 80 minutes of arc on a dark ground has been investigated for the dark adapted extra-foveal retina under conditions of steady fixation, with variation of intensity, wavelength and eccentricity, and for several observers. A time delay of a few seconds followed by a rapid reduction of subjective brightness was always found, the subjective image vanishing outside the paracentral region. It appears that the process is characteristic of both rod and cone units. The origin of the effect is discussed. La disparition subjective des objets en vision peripherique continue n'a ete ordinairement consideree que comme un obstacle a une observation satisfaisante. L'adaptation locale du stimulus de 40 × 80 minutes d'arc en fond obscur, dans les conditions d'observation continue et de fixation soutenue, a ete etudiee pour la re...
56 citations
TL;DR: In this paper, the authors defined the contrast of a self-luminous or incoherently illuminated object as a function of the size of the object (or the spacial frequency), the relative aperture of the imaging system and its state of correction.
Abstract: The contrast K of a self-luminous or incoherently illuminated object is defined by K = (J max - J min)/(J max + J min) where J is the intensity of illumination. When an optical system forms an image of the object, the contrast is reduced, due to diffraction, aberrations, and veiling-glare. The reduction of contrast is a function of the size of the object (or the spacial frequency), the relative aperture of the imaging system and its state of correction. An apparatus is described for measuring this contrast transmission function for miniature camera lenses. The objective to be tested projects on to a narrow slit the image of a rotating grating having varying frequencies, and K = 1. A photomultiplier gives an output proportional to the intensity of transmitted light and a cathode ray oscillograph synchronised with the rotation of the grating gives a stationary representation of the light distribution in the image. Results obtained with this apparatus from miniature camera lenses are given and discussed for ...
17 citations
TL;DR: In this article, the amount of light required for the detection of parallel line grating patterns was measured with a variety of wavelength distributions of the test light, and the results indicated that when the visual angle subtended by the smallest elements of detail in a grating pattern is 5 minutes of arc or less, detection of the pattern is based primarily on the function of the cones.
Abstract: The amount of light required for the detection of parallel line grating patterns was measured with a variety of wavelength distributions of the test light. Grating patterns ranging from very coarse lines to very fine lines were used. All measurements were made with the eyes of observers adapted to darkenss and were based on short flash presentations of the test pattern. The results are interpreted to indicate that when the visual angle subtended by the smallest elements of detail in a grating pattern is 5 minutes of arc or less, detection of the pattern is based primarily on the function of the cones. For progressively coarser patterns, the receptor population upon which detection depends may consist primarily of cones, of a combination of rods and cones, or primarily of rods. Restriction of the illumination to longer wavelengths will emphasize cone function; the use of other distributions of illumination may emphasize rod function, or the combined function of both rods and cones. La quantite de lumiere n...
15 citations
TL;DR: In this paper, a more exact treatment of the off-centre cases for circular and rectangular apertures for interferometry has been proposed, and the results show that approximate formulae can give quite incorrect results at path difference and obliquity values which still allow fringes to be observed when isotopic light sources are used.
Abstract: Recent papers by Bruce [1] and Thornton [2] have described the influence of oblique rays on the measurement of length by interferometry. On-centre apertures were treated with adequate exactness but off-centre apertures were treated approximately. This paper deals with a more exact treatment of the off-centre cases for circular and rectangular apertures. The treatment is adequate for all cases that may occur in practice and the expressions for on-centre cases are quickly derivable. The results show that approximate formulae can give quite incorrect results at path difference and obliquity values which still allow fringes to be observed when isotopic light sources are used. Fringe displacement curves have been drawn to show the main characteristics of the obliquity effects, and these have been confirmed experimentally. Deux recents articles de Bruce [1] et Thornton [2] ont traite de l'influence des rayons obliques sur les mesures interjerometriques de longueurs. Le cas des ouvertures centrees y etait traite...
12 citations
TL;DR: In this paper, a system of great relative aperture is calculated using scalar diffraction theory, giving a new expression for light intensity, following Green and Wolf, and the aberration-free diffraction image is studied in detail.
Abstract: Es werden Systeme grosser relativer Offnung mit Hilfe der skalaren Beugungstheorie behandelt. Wesentlich ist dabei ein im Anschluss an Green und Wolf aufgestellter neuer Ausdruck fur die Lichtintensitat. Das aberrationsfreie Beugungsbild wird eingehend untersucht. Systems of great relative aperture are calculated using scalar diffraction theory, giving a new expression for light intensity, following Green and Wolf. The aberration-free diffraction image is studied in detail. Des systemes a grande ouverture relative sont calcules a l'aide de la theorie scalaire de la diffraction. En meme temps, une nouvelle expression de l'intensite de la lumiere est etablie, d'apres Green et Wolf. L'image de diffraction, sans aberrations, est etudiee.
9 citations
TL;DR: In this paper, the structural resolving power of an optical system with annular apertures was investigated and it was concluded that the image of an extended object showing low-contrast fine structure begins to show visible deterioration when the reduction in the structural resolution power of the optical system by aberrations or by central obstruction reaches about 20 per cent.
Abstract: A brief account is given of the reasons why the classical notion of resolving power fails to provide a satisfactory quality criterion of optical systems designed to form images of extended objects. The discussion indicates that a quantity here called the structural resolving power, which is formally identical with an assessment proposed independently by Schade (1952) and Fellgett (1953), seems well suited to replace the old notion of resolution limit in evaluating the images of extended objects. On the basis of known results about images by systems with annular apertures, and of the rather close relation between the structural resolving power of an optical system and its information-passing capacity, it is concluded that the image of an extended object showing low-contrast fine structure begins to show visible deterioration when the reduction in the structural resolving power of the optical system by aberrations or by central obstruction reaches about 20 per cent. L'auteur rappelle brievement les raisons ...
9 citations
6 citations
TL;DR: In this article, the authors investigate how the size of the aperture through which the light enters the interferometer affects the visibility of the fringes, in the case of a narrow slit and a circular aperture.
Abstract: The visibility of two-beam interference fringes is of interest in the measurement of long lengths, as well as being one of the earliest means of analysing the fine structure of spectral lines. The aim of this paper is to investigate how the size of the aperture through which the light enters the interferometer affects the visibility of the fringes, in the case of a narrow slit and a circular aperture. La visibilite des franges d'interference a deux faisceaux est interessante pour la mesure de longues distances, de meme qu'elle a ete l'un des moyens utilise en premier lieu pour l'analyse de la structure fine des raies spectrales. Le but du travail presente dans cet article est de rechercher comment la dimension de l'ouverture a travers laquelle la lumiere penetre dans l'interferometre affecte la visibilite des franges dans le cas d'une fente fine et dans celui d'une ouverture circulaire. Zweistrahl-Interferenzen finden bei der Messung grosser Langen Anwendung und sing uberdies eines der ersten Mittel bei d...
TL;DR: The binocular matching technique, in which the sensation of brightness of an after-image formed in one eye only is balanced by a comparison light stimulus in the other eye, has been used for further studies of the positive after- image.
Abstract: The binocular matching technique, in which the sensation of brightness of an after-image formed in one eye only is balanced by a comparison light stimulus in the other eye, has been used for further studies of the positive after-image. By dark-adapting each eye in turn, it is shown that the cone receptors in the retina are mainly responsible for the after-image, whereas the matching stimulus acts mainly on the rods. The decay curves of the after-image in white light for two observers are given, with a discussion of the region in which after-image effects follow a reciprocity law. The after-images formed by monochromatic stimuli give exponential decay curves, compared with power-law decay curves for white light stimuli. It is suggested that the origin of positive after-images may be the electrotonic polarisation of the axons of the ganglion cells. La technique de fusionnement binoculaire dans laquelle la sensation de brillance d'une « image consecutive » formee dans un œil est compensee par un stimulus lum...
TL;DR: In this article, the Quelques Proprietes Optiques des Milieux Stratifies Symetriques (QPOMS) are used to define symetria.
Abstract: (1957). Quelques Proprietes Optiques des Milieux Stratifies Symetriques. Optica Acta: International Journal of Optics: Vol. 4, No. 1, pp. 42-43.
TL;DR: In this article, the distribution of light in the images of edges, strips and gratings in the presence of spherical aberration is calculated using wave theory, and its influence on image quality is illustrated by examples.
Abstract: Die Lichtverteilung im Bild von Kante, Streifen und Gitter wird unter Berucksichtigung des Offnungsfehlers auf wellenoptischer Grundlage theoretisch berechnet und sein Einfluss auf die Bildgute an Beispielen gezeigt. La repartition de la lumiere dans l'image de tests (bord, bandes ou grille) est calculee theoriquement en fonction de l'aberration spherique, a partir de l'optique ondulatoire et son influence sur la qualite de l'image est montree dans plusieurs exemples. The distribution of light in the images of edges, strips and gratings in the presence of spherical aberration is calculated using wave theory, and its influence on image quality is illustrated by examples.
TL;DR: In this paper, explicit formulae for transmission and reflection of a system of plane parallel thin films are given for coupling effects arising in various possible arrangements, described by coupling factors.
Abstract: Fur die Durchlassigkeit und Reflexion eines Schichtsystems, bestehend aus planparallelen Teilsystemen, werden explizite Formeln angegeben. Die durch die spezielle Art der Zusammensetzung bedingten Kopplungseffekte werden durch « Kopplungsfaktoren » beschrieben. Explicit formulae are given for the transmission and reflection of a system of plane parallel thin films. Coupling effects arising in various possible arrangements are described by coupling factors. Des formules explicites sont donnees ici pour le calcul de la transmission et reflexion d'un systeme de couches minces plan-paralleles. Les effets de couplage resultant des diverses dispositions possibles sont decrits a l'aide des facteurs de couplage.
TL;DR: In this paper, Chandrasekhar's approximate method of resolution is summarized; this method is applied to a layer of haze and to the sea and the approximations are discussed; the equation governing the penetration of radiation in a scattering medium is given.
Abstract: Apres avoir rappele l'equation regissant la penetration du rayonnement dans un milieu diffusant et resume la methode de resolution approchee de Chandrasekhar, nous donnons des exemples d'application de cette methode a une couche de brouillard et a la mer, et nous discutons les approximations faites. Die Gleichung fur das Eindringen einer Strahlung in ein streuendes Medium wird aufgestellt und. kurz die Methode von Chandrasekhar fur eine Naherungslosung angegeben. Dann folgen Anwendungsbeispiele dieses Verfahrens auf eine Nebelschicht und auf das Meer und schliesslich eine Diskussion uber die erzielten Naherungen. The equation governing the penetration of radiation in a scattering medium is given and Chandrasekhar's approximate method of resolution is summarised; this method is applied to a layer of haze and to the sea and the approximations are discussed.
TL;DR: In this article, weitere Sehscharfenmessungen with fernrohrbewaffnetem Auge berichtet, deren Auswertung eine unmittelbare Aussage gestattet, in welcher Weise Fernrohrvergrosserung und Objektivoffnung in die Sehleistung im Dammerungs-und Nachtsehen eingehen eingeshen.
Abstract: Es wird uber weitere Sehscharfenmessungen mit fernrohrbewaffnetem Auge berichtet, deren Auswertung eine unmittelbare Aussage gestattet, in welcher Weise Fernrohrvergrosserung und Objektivoffnung in die Sehleistung im Dammerungs-und Nachtsehen eingehen Der alte Meinungsstreit, ob im Gebiet des Dammerungssehens eine Fernrohrubervergrosserung vorteilhaft ist oder nicht, wird dahingehend entschieden, dass bei gleicher Objektivoffnung eine starkere Vergrosserung eine Erhohung der Sehscharfe fast im gesamten Anwendungsgebiet der Feldstecher bewirkt Der Vorteil ist am grossten beim Tagessehen (uber 10 asb), ist im Dammerungssehen (100-10-2, Mondschein etwa 100,5 asb) immer noch betrachtlich Bei etwa 10-3 asb ist die Fernrohrleistung von der Vergrosserung unabhangig, erst unterhalb dieser Leuchtdichte wirkt sich eine Ubervergrosserung nachteilig auf die Sehleistung aus, die Fernrohraustrittspupille sollte hier also die Grosse der Augenpupille haben, zumindest nicht wesentlich kleiner sein Die Sehscharfenmessu
TL;DR: In this paper, the phase shift caused by boundary reflections when a transparent film is interposed between the interferometer flats was calculated and represented in diagrams with rolling circles, and the results agreed satisfactorily with the calculations.
Abstract: Multiple-beam interferences show a remarkable effect owing to boundary reflections when a transparent film is interposed between the interferometer flats Similar conditions occur in all interferometric thickness measurements of transparent films The phase shift so caused is calculated and represented in diagrams with rolling circles Measurements were made with multiple-beam interference on zinc sulphide films deposited on silver, and the results agreed satisfactorily with the calculations If the boundary reflections are neglected in the case of multiple-beam interference the error in the determination of the film thickness is at most about λ / 2 π, even if the difference in refractive index is small The consequences of this are considered for the interferometric measurement of biological specimens Les interferences a ondes multiples donnent lieu a un effet remarquable propre aux reflexions limites quand une lame transparente est interposee entre les plans de l'interferometre Ces phenomenes se produ
TL;DR: In this paper, an interference photometer is described which measures the distribution of intensity and phase in the image of a point source, and is essentially an analogue computor for the evaluation of diffraction integrals.
Abstract: SUMMARY. - An interference photometer is described which measures the distribution of intensity and phase in the image of a point source. It is a simple modification of the MACH-ZEHNDER type of interferometer, and is essentially an analogue computor for the evaluation of diffraction integrals. The photometric advantage of this method has been discussed in relation to the method of direct scanning. This interference method also gives the distribution of phase directly — a measurement which was not previously possible. The accuracy of the method is found to be greater than that to be expected from direct scanning methods. The effect of a finite size of source has also beenstudied inrespect of the visibility of fringes and its influence on the results obtained. SOMMAIRE. - Description d'un photometre interferometrique permettant de mesurer la distribution d'inlensite de phase dans l'image d'un point lumineux. C'est une modification simple de l'interferometre du type MACH-ZEHNDER. Calculateur analogique pour ...
TL;DR: In this article, the number of rods per sensory unit under these conditions has been calculated, using two luminous points, of extra foveal visual acuity and its relation to the density of sensory units in darkness.
Abstract: Nous etudions l'acuite visuelle sur l'extrafovea en utilisant deux points lumineux et sa relation avec la densile des unites sensorielles dans l'obscurite. Nous faisons le calcul du nombre de bâtonnets par unite sensorielle dans l'obscurite. A study has been made, using two luminous points, of extra foveal visual acuity and its relation to the density of sensory units in darkness. The number of rods per sensory unit under these conditions has been calculated. An zwei leuchtenden Punkten wird die extrafoveale Sehscharfe und ihr Verhattnis zur Empfindungseinheit beim Nachtsehen untersucht. Die Zahl der Stabchen lasst sich aus der Empfindungseinheit beim Nachtsehen berechnen.
TL;DR: In this article, a study of the relationship between the real and subjective world, limited by visual perception, shows that subjective space is constructed from visual sense data, and that subjective spaces are constructed from a logishehen Begrundung der realen Welt and an exakte Beschreibung der Gestalt der visuellen Umwelt.
Abstract: Die Untersuchung der Zusammenhange zwischen realer Welt und Sinnenwelt, beschrankt auf die visuelle Wahrnehmung, zeigt, dass der subjektive Raum durch Informationen aufgebaut wird, die die menschliche Sehapparatur aus dem objektiven Raum erhalt. Daraus ergibt sich einerseits der Versuch einer logisehen Begrundung der realen Welt und andererseits eine exakte Beschreibung der Gestalt der visuellen Umwelt, d. h. des Sehraumes. Dieser ist endlich und fuhrt eine pulsierende Bewegung mit Halbtagsperiode aus. Dabei erfahren Sonne und Mond schwankende Wahrnehmungsgrossen, die sich streng errechnen lassen. Ferner wird bewiesen, dass im Nahbereich, dem eigentlichen Lebensraum des Menschen, die aus Grunden der Orientierung zu fordernde Ubereinstimmung zwischen objektivem und subjektivem Raum gegeben ist. Study of the relationship between the real and the subjective world, limited by visual perception, shows that subjective space is constructed from visual sense data. From this an attempt can be made to establish a l...