摘要:

One method which has been suggested for reducing speckle in the holographically reconstructed image of a diffusing object is the use of a moving aperture in the pupil plane of the imaging lens (this is equivalent to sampling the spatial frequency spectrum of the object). An expression is derived for the average power spectrum of the speckle in the image of a coherently illuminated diffusing object when a number of exposures are superimposed with a shift of the sampling aperture located in the spatial frequency plane between successive exposures, and experimental results are presented which confirm that an appreciable reduction in speckle can be obtained even when the shift of the sampling aperture between two exposures is less than its dimensions. This analysis is then extended to the case of a rectangular sampling aperture which is moving continuously for the duration of the exposure. The results show that, for a given range of movement, an exposure with a continuously moving aperture should be more effective in suppressing speckle than a series of exposures with the aperture moved in steps by its own width between exposures.

ISSN:0030-3909    

DOI:10.1080/713818900

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Plane wave volume holograms have been stored in KCl: Na utilizing the dichroic properties of FAcentres. Diffraction efficiences, up to 5·4 per cent, resulting predominantly from phase modulation have been measured for 496·5 nm. The observed results are explained in terms of the dispersion theory, and maximally achievable diffraction efficiencies are predicted for the entire FAabsorption range.

ISSN:0030-3909    

DOI:10.1080/713818898

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Von einem Protanomalen wurden spektrale und entsättigte Farbreize an einem visuellen Farbmeßgerät abgeglichen; diese Abgleiche wurden von einem Protanopen, einem Deuteranopen und einem Deuteranomalen beurteilt. Ergebnisse: (1) Protanomale und Deuteranomale stehen sicherlich nicht im gegenseitigen Verhältnis einer Reduktionsform. (2) Auf der Beschreibungsebene der Farbart (Chromatizität) herrscht im mittel- und langwelligen Spektralbereich Übereinstimmung zwischen den Farbgleichungen des Protanomalen und Protanopen wie auch zwischen den Farbgleichungen des Protanomalen und Deuteranopen. Eine vollständige Klärung von (2) unter Einschluß der Helligkeitsverhältnisse erfolgt in der anschließenden Arbeit [37].

ISSN:0030-3909    

DOI:10.1080/713818906

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Farbabgleiche eines Protanomalen wurden von einem Protanopen und einem Deuteranopen insbesondere auch der Helligkeit nach beurteilt. Zu diesem Zwecke wurden die ermittelten Farbvalenzen in ein Chrominanz-Luminanz-System transformiert. In diesem ist ersichtlich, daß weder der Protanop noch der Deuteranop die Farbgleichungen des Protanomalen für uR 550 nm genau anerkannten. Daraus wurde geschlossen, daß die untersuchte Protanomalie durch zwei alterierte (oder ‘anomale’) Sehpigmente charakterisiert ist.

ISSN:0030-3909    

DOI:10.1080/713818899

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Dans cette note on donne des indications sur les possibilités d'une nouvelle méthode de mesure que les auteurs ont commencé d'appliquer. On présente l'utilisation de fibres optiques dans un cas d'étude microscopique en hydrodynamique des milieux poreux. D'autres applications sont évoquées. Une amorce est faite dans la perspective d'un traitement numérique des informations que cette méthode permet d'acquérir.

ISSN:0030-3909    

DOI:10.1080/713818907

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Modulation transfer functions of the dioptrics of the human eye for white (equal energy distribution) light were calculated for different pupil sizes from experimental data on the aberrations. The largest aberration is the chromatic difference of focus. Since this aberration is well known quantitatively and is subject to small individual differences only, the calculated modulation transfer functions can be considered as representative for human eyes in general. The present calculations, the fundus reflection measurements of the line-spread function by Campbell and Gubisch [1], and the measurements of retinal scattering by Ohzu and Enoch [2] confirm each other. Modulation transfer functions were also calculated for just noticeable focusing errors, and may be informative on the tolerance limit to visual image quality. The calculations have been extended to the special conditions of vision at low luminances.

ISSN:0030-3909    

DOI:10.1080/713818902

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Theoretical counterparts are presented for the experimental efficiency curves obtained by Hutley and Bird in the visible region for a holographic grating covered consecutively with films of silver, aluminium and gold. It is thus shown that the recently developed formulation of Maystre, which takes into account the finite conductivity of the grating surface, gives results in quantitative agreement with experiment. This not only validates the theory, but also demonstrates that the difficulties associated with profile determination and oxide films, which have in the past led some experimenters to renounce the visible region and perform measurements on millimetre-wave gratings, are not in fact insuperable. It is also shown that only a theoretical model which takes into account groove depth effects can hope to predict accurately the locations of regions of enhanced energy absorption by gratings.

ISSN:0030-3909    

DOI:10.1080/713818903

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713818901

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/716099346a

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor