摘要:

General equations describing holographic fringe patterns have been derived in an earlier publication. In this paper an experimental investigation of the equations is described. The fringe patterns resulting from known surface displacements are observed from two positions and the measured fringe spacings are compared with those predicted theoretically. Two forms of displacement are considered: (i) rigid-body translations, (ii) linear displacement gradients. Results indicate that experimental observations are in close agreement with those predicted theoretically. The observation of plane strain is demonstrated in order to give a practical example of a problem involving a combination of the displacement classes (i) and (ii).

ISSN:0030-3909    

DOI:10.1080/713818888

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The method of the caustic, as used in testing optical systems or surfaces, has been examined for two measuring techniques, namely bisecting slit images with a wire and photographic recording of slit images for later measurement. Diffraction effects have been considered and the sensitivity of the methods estimated. Both techniques have been shown to be more accurate than when using a wire as spatial filter, the better results being obtained with the photographic method. The incidence of errors from misalignment of the measuring equipment has also been considered and a tolerance derived.

ISSN:0030-3909    

DOI:10.1080/713818894

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

When a perpendicularly stretched thread is fixated at its centre with the eyes in symmetrical convergence, the thread has to be tilted around the fixated point with its top away from the observer for it to appear perpendicular. This fact was recognized by a number of investigators as early as the 1850's. For this reason both Hering and Helmholtz described the horopter as an ‘upside-down’ cone. The present investigation employs a twin point-light source apparatus to estimate the orientation and the shape of a subjective equidistant line that lies in the median plane of the observer. Since the method of measurement depends on retinal disparity clues, this locus corresponds to the stereoscopic frame of reference in the median plane. The results are in qualitative agreement with previous findings. Quantitatively, however, they show a much smaller tilt of the reference plane than the ones reported by Helmholtz and others. The stereoscopic sensitivities of the retinal regions at the various elevations above and below the fovea show an orderly variation. The implications of the findings are discussed with reference to past theories on cyclo-torsional eye movements as well as concepts regarding the shape of the horopter in general and the vertical horopter in particular.

ISSN:0030-3909    

DOI:10.1080/713818889

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The principle of the arrangement and measurement results obtained by means of a reflectometer for measurements of reflectivity of dielectric mirrors are described. The device permits the measurement of the transmittance of mirrors and light scattering on the surface and will allow the investigation of the properties of dielectric mirrors designed especially for lasers. The accuracy of the device is better than - 0·1 per cent and the spectral range covers the visible and the near infra-red regions.

ISSN:0030-3909    

DOI:10.1080/713818890

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The model representing a powdered sample as a collection of uniformly sized rough-surfaced spherical particles is used to derive expressions for the reflectance properties of luminescent powders. The three cases treated are spontaneous emission, emission induced by an exponentially attenuated beam of radiation, and emission induced by light. The equations obtained are compared with those obtained using the differential equation method.

ISSN:0030-3909    

DOI:10.1080/713818891

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

In contrast to ordinary light diffraction, it is established here that in Fresnel diffraction of gaussian mode laser beams of finite size at a straight edge there is a theoretical limitation in the total number of fringes seen; besides, there is a minimum permissible focusing of the laser beam, beyond which the diffraction fringes are washed out to an exponential fall-out. These conclusions justify the results obtained earlier [3].

ISSN:0030-3909    

DOI:10.1080/713818896

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Definitions of the coherence time, coherence area and coherence volume are proposed for superposed coherent and chaotic radiation, such as laser radiation above the threshold, on the basis of the photon statistics of the radiation. Such definitions may contribute to a unified judgment of the coherence properties of the radiation in any order, while the definitions usually used are connected with interferometric measurements of the second-order coherence properties. A close relationship to the definitions proposed earlier in the literature for chaotic radiation is shown.

ISSN:0030-3909    

DOI:10.1080/713818895

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713818893

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713818892

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor