摘要:

In the present paper we have studied the propagation of optical beams in a circularly curved graded-index fibre. A closed-form expression for the kernel has been obtained, from which one can determine the field distribution at any point inside the fibre. For the special case of a Gaussian beam incident on the face of a fibre, an analytic expression for the intensity distribution has been obtained from which one can easily determine the path of the centre of the beam. Several incident conditions have been considered and it is shown that the beam, in general, follows a skew path, though there are specific cases when it stays in the meridional plane only. In practical cases the ellipticity introduced due to the bending of the fibre, is very small.

ISSN:0030-3909    

DOI:10.1080/713819681

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Formation of interference fringes in the holographic measurement of displacement distribution on a rough surface or flow velocity distribution on a section plane in a fluid is analysed using the concept of random process and the stationary phase method. The displacement or velocity is assumed to vary slowly on the surface. Restrictions are not severe in other respects: the rough surface may be curved; the illumination wave need not be plane; the entrance pupil of the observing optical system may be located at a finite distance from the object; many types of holographic interferometry such as multiple-exposure or time average method are taken into consideration. The analysis is made for two cases: one is when the observation point is far from the rough surface and the other is when it is far from the entrance pupil of the observing system, including the observation near the rough surface. In the former case the resultant intensity at the observation point can be considered as the superposition of the constituent fringe intensity arising from the displacement of each contributing point on the rough surface. In the latter case the intensity can be obtained as the integral of the contributing part of the constituent fringe intensity over the entrance pupil.

ISSN:0030-3909    

DOI:10.1080/713819682

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Nous avons réalisé des filtres interférentiels étroits pour le proche ultraviolet (280 nm) en prenant comme bas indice la cryolithe et comme haut indice le fluorure de plomb. Les résultats obtenus (Tmax= 60 pour cent, j u = 27 +) sont reproductibles et les empilements conservent leurs caractéristiques durant un an et plus. Nous avons néanmoins rencontré quelques difficultés dans le contrôle de l'évaporation, notamment des inversions du sens de variation de la transmission, que nous avons tenté d'expliquer.

ISSN:0030-3909    

DOI:10.1080/713819686

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The paper uses a general treatment for obtaining the expressions of the scattered field and intensity in the Fraunhofer space, within the range of validity of the quasi-monochromatic approximation. As a result, the relation between the object wave and the object is obtained. It is suggested that the coherence characteristics of the object wave are best described by a volume average of the two-point coherence factor normally used, and an expression of the deterioration of coherence in a random medium is obtained. The paper suggests that the definition of mutual intensity ought to be analysed.

ISSN:0030-3909    

DOI:10.1080/713819679

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Based on the theory of coupled waves the amplitude of the first-order diffracted wave and the diffraction efficiency is calculated for sequentially superposed plane gratings that are stored in dielectric transmission volume holograms. Using suitable approximations, both the Bragg-angle incidence and any deviations can be described. The grating interaction effects make it possible to couple the incident energy from one wave to another and to build up beam-couplers and splitters with certain coupling parameters. These coupling properties are adjustable in a definite manner by the recording process.

ISSN:0030-3909    

DOI:10.1080/713819684

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713819676

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713819685

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713819683

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713819678

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713819687

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor