摘要:

Laser transit anemometer cross-correlation functions acquired in the wakes of turbine blades in a linear transonic cascade have been observed to have an oscillatory form. Vortex shedding and spatially non-Poisson particle concentration arguments are proposed to account for this previously unobserved behaviour in the light scattering data.

ISSN:0030-3909    

DOI:10.1080/713820757

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

For an in-plane mounting, using a toroidal concave grating, we have found a condition giving stigmatic images for all wavelengths by means of the rotation of the grating and a slight movement of the incident and exit slits with increasing rotation angle, ε, of the grating. For this mounting, the central diffracted ray is at right angles to the central incident ray, and the distance,r′, between the exit slit and the centre of the grating is equal to the distance,r, between the incident slit and the grating centre. If the radius of curvature, R2, of the grating in the sagittal direction is chosen to be one-half of the radius of curvature, R1, in the tangential direction, and the relation r=(R1√2)sec & is maintained, a non-astigmatic image can be obtained regardless of the value of ε.

ISSN:0030-3909    

DOI:10.1080/713820764

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Optical phase changes of visible radiation in transmission through evaporated gold and tellurium thin films were determined using the Rayleigh-Lowe refractometer. The variation of the phase change in transmission with thickness was utilized to determine the absorption coefficient,ku, for both films as well as the refractive index,nu.

ISSN:0030-3909    

DOI:10.1080/713820754

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713820761

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713820765

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713820772

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/716099581a

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

From an algebraic modification of the Ewald microscopical theory of diffraction follows the dispersion relation valid from X-ray to visible-light regions. In the far-U.V. region we deduce from it an approximate dispersion relation and the generalized Snell law. The dependence of the refractive indices on the angle of incidence and the birefringence of a cubic crystal are demonstrated by numerical calculations based on our general formulae.

ISSN:0030-3909    

DOI:10.1080/713820760

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The measurement of the time-dependent spectrum of non-stationary radiation is of interest, for instance, in the field of ultrashort-time spectroscopy using picosecond lasers. The incident non-stationary radiation is characterized by the time-dependent input spectrum. The electric field strength of the radiation in the exit plane of a grating spectrometer and of a prism spectrometer is analysed in terms of its dependence on time and on the spectral coordinate. The action of the grating spectrometer is regarded as a special case of diffraction at an arbitrary diaphragm. The intensity registered by a square-law detector as a function of time and the spectral coordinate (output spectrum) is calculated as a function of the input spectrum. The input spectrum can be determined from the output spectrum by mathematical operations for cases important in practise (very short light-pulses, intrinsically stationary radiation). Moreover, the conditions are investigated under which the output spectrum resembles the input spectrum, taking into account the influence of noise. Two examples of intrinsically stationary radiation (bandwidth-limited pulse, fluorescence of a two-level system) are studied in more detail. For experimental verification the ouput spectrum of a single ultrashort light pulse has been measured under the condition of different spectrometer time constants.

ISSN:0030-3909    

DOI:10.1080/713820769

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Gabor's expansion of a signal into a discrete set of properly shifted and modulated versions of an elementary signal is introduced; several examples of elementary signals are considered. An arrangement is described which is able to generate Gabor's expansion coefficients of a one-dimensional signal by optical means. An important feature of the optical arrangement is that it accepts the one-dimensional signal on a raster format; hence, the two-dimensional nature of the optical processing system is fully utilized.

ISSN:0030-3909    

DOI:10.1080/713820771

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor