摘要:

The results are presented of a study of the spectroscopic properties of blazed interference diffraction gratings for wavelengths between 121.6 and 351 nm. It is found that they combine the high efficiency of ruled gratings with the spectral purity of gratings produced interferometrically.

ISSN:0030-3909    

DOI:10.1080/713818956

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

It is shown how the contrast of a polychromatic speckle pattern can be calculated from the spectral coherence of the scattered amplitude. For gaussian surfaces and relatively narrow spectral profiles an analytical relationship between speckle contrast and r.m.s. surface roughness is derived. The theoretical results are compared with available experimental data and discrepancies are explained.

ISSN:0030-3909    

DOI:10.1080/713818954

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

In this paper we discuss the reconstruction of a weak phase-amplitude object from its intensity image. This problem occurs in electron microscopy where the weak object approximation holds for not too low accelerating voltages (E≳ 100 keV). Isoplanatic imaging is assumed. The illumination is supposed to be quasi-monochromatic and coherent. This reconstruction problem has often been treated in the literature [11, 12]. The assumption which has tacitly been made in these articles is that the background wavefunction is real. This is not true in general. E.g., when tilted illumination is used and/or non-isoplanatic aberrations are present the background wavefunction is complex. This makes a reconsideration of the traditional approaches necessary. The quantities to be reconstructed are the phase shift and amplitude attenuation due to the object. The reconstruction proceeds in two steps. The first step is essentially the determination of the complex amplitude in the exit pupil from the intensity distribution in the image plane. For a mixed phase-amplitude object we need two exposures in order to calculate this complex amplitude. For a pure phase or amplitude object one exposure is sufficient. The complex amplitude arises as the (unique) solution of two coupled Volterra integral equations. The traditional difficulties (Blaschke factors) do not occur. In the second step the phase shift and amplitude attenuation are determined from the complex amplitude in the plane of the exit pupil. Phase shift and amplitude attenuation can be determined with arbitrary accuracy if noise may be neglected.

ISSN:0030-3909    

DOI:10.1080/716099350

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The results obtained in the preceding paper [1] are generalized to deal with non-isoplanatic imaging using an extension of a mathematical technique due to Cauchy.

ISSN:0030-3909    

DOI:10.1080/716099350a

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A Fourier-series representation of a Fresnel zone plate is set up and used, with a paraxial approximation, to predict features of the image-forming and Fourier-transforming properties of the plate. These properties are compared and contrasted with those of a lens, and examples of a Fraunhofer diffraction pattern from a plate and a lens are illustrated.

ISSN:0030-3909    

DOI:10.1080/713818955

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Scattering diagrams, calculated from a rigorous theory, are presented for wavelengths comparable to the characteristic dimensions of the protuberances.

ISSN:0030-3909    

DOI:10.1080/713818960

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A holographic method for reconstructing the polarization of light from a photoelastic model is presented. Three typical patterns associated with the principal stresses, that is, Nisida and Saito's pattern in a Mach-Zehnder inter-ferometer, Fourney and Mate's pattern in double-exposure holographic inter-ferometry and dark-field isochromatics in conventional photoelasticity, are obtained from one double-exposure hologram by observing the reconstructed image having information of the original model's polarization. Though the experimental condition is more stringent than that of Fourney and Mate's method, the intensity pattern obtained here is simpler than theirs. The present method can completely separate dark-field isochromatics from other patterns and does not require an optically flat and parallel plane model. The analytical description of the method and the experimental verification are described.

ISSN:0030-3909    

DOI:10.1080/713818961

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The simplified particle model theory of diffuse reflectance spectroscopy disagrees with Melamed's more sophisticated particle model theory for samples with large index of refraction values. The simplified particle model theory was corrected for the direction of reflection of light externally incident on a particle. Diffuse reflectance values calculated using the corrected equation agree very well with those calculated by Melamed's equations.

ISSN:0030-3909    

DOI:10.1080/713818962

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/716099352a

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/716099351a

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor