Showing papers in "Journal of Modern Optics in 1960"

A Study of Troxler's Effect

Abstract: (1960). A Study of Troxler's Effect. Optica Acta: International Journal of Optics: Vol. 7, No. 3, pp. 219-236.

Small-field Tritanopia and the Effects of Voluntary Fixation

Abstract: Recently published wavelength discrimination curves for point sources have shown no tritanopic confusion of blue and green, and it has been suggested that this was because the observers scanned the field, instead of fixating on it. Curves measured by the author, also without fixation, but over a different range of field sizes and luminances, do show tritanopic confusion, although it is not as marked as in the older investigations. The curves also show that lowering the luminance, at a given field size, produces a different effect, and that discrimination between blue and violet, at 430 mμ, can be very good when fixation is avoided.

Extra-foveal Colour Metrics

Abstract: A series of monochromatic equal-brightness stimuli of subtense 40′ x 80′ was established through the spectrum by direct comparison with a neighbouring 530 mμ patch of retinal illumination 10-8 phot...

Colour Confusion Produced by Voluntary Fixation

Abstract: When an observer stares at a colour-matching field, he may lose a great deal of his colour discrimination. Some find it possible to match any pair of spectral colours. Prolonged staring is not necessary, but the colours must be exactly matched in brightness. A systematic study of the fixation effects indicates that they are not due to a photochemical bleaching of pigments, but rather to the reduction of eye movements. Blue-green discrimination is affected more than yellow-red.

Nouveaux Dispositifs de Spectroscopie à Grande Luminosité

Abstract: Les trois dispositifs decrits ici permettent, lorsque le bruit de photons n'est pas preponderant, d'effectuer une analyse spectrale avec une luminosite tres superieure a celle d'un spectrometre a fentes. Le premier dispositif est un interferometre a polarisation adapte a la spectroscopie par la methode de la transformee de Fourier. Il est tres lumineux et d'un emploi commode mais ne permet pas d'atteindre un pouvoir de resolution tres eleve. Avec les deux autres dispositifs, le spectre est obtenu directement, sans calcul a posteriori. D'autre part, la disposition generale des appareils a fentes est conservee. L'idee commune aux deux dispositifs est de remplacer les fentes d'entree et de sortie par deux systemes, images l'un de l'autre a travers l'appareil, constitues de fentes multiples, de largeurs inegales et separees par des intervalles inegaux. L'element spectral privilegie qui fournit de l'organe d'entree une image superposee a l'organe de sortie est ‘filtre’ par l'organe de sortie, grâce a une propr...

Restitution des Images Aberrantes par le Filtrage des Fréquences Spatiales

Abstract: On restitue l'image prise par un objectif, dont le facteur de transmission des frequences spatiales peut etre negatif et nul, par un filtrage des frequences spatiales a l'aide de la combinaison d'un filtre absorbant et d'un filtre dephasant. On trouve qu'une image parasite apparait dans 'image restituee par suite des zeros du facteur de transmission des frequences spatiales de l'objectif de prise de vue.

Mesure Pyrométrique du Seuil Visuel Absolu

Abstract: On mesure le seuil visuel absolu en quanta lumineux de 520 mμ, au niveau de la cornee. L'energie du faisceau est determinee au moyen d'une methode pyrometrique tres precise. Les resultats confirment grosso modo ceux de Hecht, Shlear et Pirenne. On est autorise a conclure que l'absorption de sept quanta par les recepteurs retininens peut suffire a declencher une sensation liminaire.

Influence du Nombre de Traits des Mires sur la Precision des Mesures du Facteur de Transmission

Abstract: A l'ancienne notion de ‘;limite de resolution’ d'un instrument d'optique, on tend a substituer, de plus en plus, celle de 'facteur de transmission' en fonction de la frequence spatiale, qui renseigne evidemment beaucoup mieux sur la qualite de l'instrument. Dans les dispositifs utilises pour la mesure de ce facteur, une cause d'erreur peut etre le faible nombre de traits des mires ‘periodiques’ utilisees. On etudie ci-dessous l'influence de ce nombre de traits sur la precision des mesures, et les moyens de limiter l'erreur qui peut en resulter.

Phase Dispersion in Interferometry

Abstract: It is shown that the interference equation for interferometers exhibiting phase-change effects should take the form Mλ = 2d — λv/~, where v is (β — π) and β is the phase-change at reflection for one reflecting surface. Several recent treatments of the phase-change on reflection are critically examined and it is shown that the phase-dispersion deduced from them is inconsistent with generally accepted experimental results for interferometers with silver films.

A Monochromator for the Vacuum Ultra-violet

Abstract: The design and construction of a vacuum ultra-violet monochromator suitable for photo-electric spectrophotometry and photo-ionization studies at short wavelengths is described. It incorporates a device for moving the exit slit along the beam to keep the spectrum in focus as the grating is rotated. The tank is divided transversely into two sections for permitting easy adjustment or interchange of gratings without disturbing the driving mechanism. An elaborate system of baffles is used to reduce scattered radiation to a very low value. A variety of attachments fit on to the exit slit for the examination of solid, liquid or gaseous samples and for photoelectric or photo-ionization measurements.

Contrast Transmission and the Image Evaluation Problem

Abstract: A discussion is given, with the help of contrast-transmission theory, of the relative merits of the ray-theoretic moment of inertia, of the Strehl definition, and of the so-called photographic Strehl definition as quality evaluations of astrographic cameras and of camera lenses producing images with the familiar core-and-halo structure. The ‘interferometer quality’ assessment of Coleman et al. [1] is also considered. The general discussion is supplemented in §§ 3 and 4 by a fairly detailed examination of the effects of applying the second and third evaluations to a system with primary spherical aberration. It is concluded that, when a system with primary spherical aberration forms images with a core-and-halo structure, the image quality near best focus depends critically on the properties of the image core, where diffraction effects may be dominant even when the total wave aberrations are large, and the inference is drawn that in evaluating the performance of a photographic system forming core-and-halo im...

Changes in the Positions of the Invariant Colours with the State of Adaptation of the Eye

Abstract: The colours which retain their daylight appearances to each of five observers under three cases of chromatic adaptation and one case of white adaptation are determined from binocular matching data The assumption of the linearity of the relationship between the tristimulus values of the corresponding colours which underlies the analytical treatment of the data is shown to be fulfilled in all the cases, the evidence being the agreement between the observed matches and those computed from the linear transformation The invariant colours under each of the adaptation conditions were calculated for each observer and also from the mean matches of all the observers The scatter of the individuals' invariants about the invariants obtained from the mean matches provides a criterion for testing the significance of the changes of the latter from one state of adaptation to the other The analysis clearly reveals significant changes of the invariants in two regions

Temperaturmessungen an Einer Russflamme

Abstract: Die wahre Temperatur einer durch Russ leuchtenden Flamme kann erst dann angegeben werden, wenn die optische Dicke der Flamme bestimmt worden ist. Dazu sind im wesentlichen zwei Methoden bisher genannt und durchgefuhrt worden. Entweder werden schwarze und Farbtemperatur, oder die schwarze Temperatur der einfachen und der durch Spiegelung verdoppelten Flamme gemessen. Es sind aber noch weitere Methoden, vor allen Dingen die der Messung der Farbtemperatur von einfacher und gespiegelter Flamme, denkbar. Rechnungen dazu und Messungen an der Hefnerflamme werden ausgefuhrt. Die Ergebnisse werden verglichen und die einzelnen Methoden auch in bezug auf ihre Fehlerquellen diskutiert.

Constantes Optiques et Variations de Phase de L'or en Couches Minces

Abstract: On a mesure pour 18 couches minces d'or d'epaisseurs massiques comprises entre 0,6 et 95 mμ les variations de phase d'une onde lumineuse lorsqu'elle se reflechit normalement dans l'air sur le metal (Δr) ou dans le quartz sur le metal (Δr′). Ces mesures, jointes a celles precedemment rapportees [1] des facteurs de reflexion et de transmission, ont permis de determiner les constantes optiques de ces couches d'or par la methode de Male.

Spectral Line Broadening Measured by Shearing Interferometric Methods

Abstract: A shearing interference method for determining spectral line widths and shapes from the visibility curve of two-beam interferences as a function of the path difference between the interfering wavefronts is described. The visibility is the Fourier transform of the intensity curve of the spectral line. In each measurement a limited number of points of the visibility curve is determined, but this is sufficient to give a rough estimation of the whole curve if the points are properly chosen. The image is preferably registered by a photographic plate which is then measured in a microdensitometer. Hence light sources of very low intensities can be investigated. Two slightly different shearing interferometers have been used, one with a Savart plate combined with an entrance slit and the other with a Wollaston-type compensating prism for large apertures. In the latter case, no entrance slit is necessary and combinations with a wide band monochromator can be made without any serious loss of intensity. The green lin...

Nachweis für Die überschreitbarkeit der von den Sampling-Expansion-Theoremen Postulierten Informationsschranken

Abstract: Wahrend in einer kurzlich erschienenen Arbeit in A.E.U. 13 (1959), ein Verfahren zur beliebig genauen Berechnung der Objekteigenschaften aus Bildbeobachtungen trotz endlicher Abbildungsapertur beschrieben wurde, wird hier ein durchsichtigerer Beweis fur die grundsatzliche Moglichkeit dieser Berechnung mitgeteilt. Damit werden die Sampling-Expansion-Theoreme, die prinzipielle Informationsschranken auch fur den Grenzfall gegen Null gehender Messfehler errichteten, als uberschreitbar und zugleich die vom Verfasser a.a.0. beschriebenen Verfahren zur Auflosungsverbesserung uber die Abbe-Grenze hinaus als legal erwiesen. Uber das Objekt wird nicht vorausgesetzt, dass die Anzahl seiner Freiheitsgrade endlich und a priori bekannt ist. Messbare endliche Schranken fur Intensitat und Ausleuchtungsbreite der koharenten Beleuchtung werden angenommen, wie das den praktischen Moglichkeiten fur jeden Fall koharenter Beleuchtung entspricht.

Eine Methode Zur Schnellen Prüfung der Leistungsfähigkeit von Objektiven

Abstract: Die Messung der Helligkeitsverteilung im Bilde von Spalten stellt eine brauchbare Methode zur schnellen Prufung von Objektiven dar. Die Spaltbreiten und der Abbildungsmasstab lassen sich so wahlen, das die Ortsfrequenzen im Bild den wichtigsten Zeitfrequenzen im Videobereich von 1-10 MHz entsprechen. Die Grenzfrequenz erhalt man aus der Steilheit der Anstiegsflanke im Oszillogramm. Die asymmetrischen Kurven erlauben mittels einer besonderen Vorrichtung eine genauere Bestimmung der Phasenfehler. Durch zusatzliche Verwendung von geeigneten Tiefpasfiltern last sich der Einflus eines Objektivs auf das Fernsehbild direkt erkennen und darstellen.

Calculation of Wavelengths from Reflecting Echelon Patterns

Abstract: Wavelengths are calculated from measurements of reflecting echelon patterns by a simplified procedure which can be carried out conveniently, using a digital computer. By measuring to the position of the centre of the envelope, rather than to an arbitrary mirror image as hitherto, it is shown that envelope correction is automatically applied and a very simple correction for non-linearity of dispersion may be made where necessary.

Einführung in das Korrigieren Optischer Systeme

Abstract: (1960). Einfuhrung in das Korrigieren Optischer Systeme. Optica Acta: International Journal of Optics: Vol. 7, No. 4, pp. 405-405.

Visibility of a Fine Line in Intermittent Illumination

Abstract: The visibility of a fine line in intermittent illumination has been examined in detail for one subject. It is shown that there are deviations from a regular response and that these effects can be associated with certain physiological frequencies exhibited by the subject, notably the tremor motions of the eyeball and the α-rhythm of the subject's cortical activity.

Einige Bemerkungen zum Problem der Optischen Bildgütebeurteilung

Abstract: Es wird die Frage nach geeigneten Kriterien und Methoden zur Bildgutebeurteilung behandelt und dabei insbesondere auf die Schwierigkeiten eingegangen, die durch die Besonderheiten der Bildubertragung durch das Betrachterauge entstehen.

Le Solide de Tolérances D'un Système Optique Travaillant à de Faibles Fréquences Spatiales†

Abstract: Nous avons trouve la condition generale de tolerance sur l'ensemble des aberrations d'un systeme optique travaillant a de faibles frequences spatiales, en utilisant la methode et le critere de Hopkins. Les resultats sont appliques a un objectif photographique et a un instrument pour la vision de nuit. Les tolerances pour ce cas se trouvent en multipliant celles de la vision de jour par un facteur fonction du contraste objet. On a fait une verification experimentale de quelques resultats. L'application de ces tolerances au calcul optique fait penser a une amelioration photometrique des instruments, par simplification du systeme et sans modifier sa performance.