摘要:

The attenuation of a near horizontal beam from a fourth harmonic YAG laser at 266 nm has been determined as a function of visual range as determined by the transmissivity at 532 nm. The measurements in the range up to 11 km-1are accounted for by Mie and Rayleigh scatter and by optical absorption, probably due to ozone. Turbulence measurements are in agreement with Tatarski's theory.

ISSN:0030-3909    

DOI:10.1080/713819264

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Für Michelson-Interferometer, die in der Fourier-Spektroskopie verwendet werden, wird die Fehlerfunktion für Spiegelverkippungen berechnet. Sie hängt von der Wellenzahl, dem Kippwinkel und dem Spiegelradius ab. Zur Verringerung der strengen Forderungen an die mechanischen Spiegelführungen wird eine numerische Korrektur der Kippfehler angestrebt. Dazu genügt die Kenntnis der Fehlerfunktion und der Beträge der Dejustierungen an den Interferogrammabtaststellen. Je nach Voraussetzung werden eine Korrekturmethode für konstante Dejustierung, eine für den allgemeinen Fall und eine Näherungsmethode für schmale Spektralbereiche angegeben und erprobt. Diese Methoden können eine komplizierte elektronisch geregelte Spiegelführung ersetzen oder deren Einsatzbereich erweitern. Es können Kippfehler toleriert werden, die ohne Korrekturrechnung zu unbrauchbaren Meßergebnissen führen würden. Die maximal zulässige Verkippung wird durch die Abnahme des Signal-Rausch-Verhältnisses bestimmt.

ISSN:0030-3909    

DOI:10.1080/713819262

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

A vector Kirchhoff diffraction theory is used to obtain the Fraunhofer diffraction patterns and total power transmissions of circular apertures illuminated by partially coherent light, characterized only by the mutual intensity function in the aperture. The results are shown to agree with experimental results previously reported in the literature, and to be valid in and beyond the paraxial region. The results for both complete coherence and complete incoherence are recovered by using the appropriate limits for the mutual intensity function.

ISSN:0030-3909    

DOI:10.1080/713819266

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

In a previous paper [1] we obtained an asymptotic expression for the irradiance fluctuations of a finite beam propagating in a random medium in the strong-scattering case (i.e. the characteristic diffraction length is large compared to the characteristic scattering length). The solution was given as the product of a plane wave portion and a finite beam correction. We show here that if the statistics of the fluctuations of the infinite and finite beams are assumed to be gaussian (in which case the fourth-order coherence function may be expressed in terms of second-order coherence functions), then the finite beam result obtained is in disagreement with our previous result. Consequently, we conclude that the statistics of a finite beam cannot be gaussian. However, assuming that the statistics of the infinite beam are gaussian leads to no contradiction. This result is an indication of the importance of finite beam size effects in irradiance fluctuation studies.

ISSN:0030-3909    

DOI:10.1080/713819268

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The effects on accuracy of incremental change during filter manufacture is discussed, in the situation of an anti-reflected receptor surface and layers which are otherwise absentee. A formula is presented by means of which corrections can be applied to some layers as compensation for ‘growth’ increments occurring in other layers.

ISSN:0030-3909    

DOI:10.1080/713819255

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

This paper presents an investigation of the self-focusing of a high power electromagnetic beam in a plasma/semiconductor in the presence of a static magnetic field when the extraordinary and ordinary modes are present simultaneously. The non-uniform heating and consequent redistribution of carriers by the Gaussian beam has been taken as the source of non-linearity in the plasma and parabolic semiconductor (e.g. Ge). In the non-parabolic semiconductor (e.g.n-InSb) the dependence of an effective electron mass on temperature has been taken as the mechanism of non-linearity. The non-linearity leads to the mutual coupling of the two modes; they support the self-focusing of each other. In a particular case where one mode is weak and the second is propagating in a self-made uniform waveguide, the weak mode propagates in an oscillatory waveguide. When both the modes have initially equal intensity, the rates of self-focusing of the two modes are different and this leads to the beam being elliptically polarized. It has also been seen that in the presence of coupling of the two modes ellipticity is increased approximately three times more than without coupling at a distance of Z = 1·2 Rd+on the axis of the beam in a plasma for the typical parameters. The phenomenon of Faraday rotation is unaffected by the self-focusing.

ISSN:0030-3909    

DOI:10.1080/713819254

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713819267

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713819261

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713819263

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/716099394a

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor