摘要:

The transfer function of the human lens system appears to be strongly influenced by the possibility to predict the input signal. Owing to this the accommodating system can respond very rapidly to a change in target distance when anticipation is used, and it is relatively slow when the subject is unable to anticipate the input signal. An optimal and a minimal transfer function is determined assuming that possibility to anticipate the input signal is relevant. The two aforementioned transfer functions are compared with sinusoidal responses which were strongly influenced by the extent of training and the attention of the subject.

ISSN:0030-3909    

DOI:10.1080/713818858

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The formation and the contrast of Fourier images of a periodic object, especially a sinusoidally transparent object, are investigated under partially coherent illumination. It becomes apparent that the spatial coherence of light affects seriously the contrast of Fourier images and the positions of the Fourier image planes.

ISSN:0030-3909    

DOI:10.1080/713818860

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

An electromagnetic beam is defined using mathematical properties of the associated angular spectrum of plane waves. It is found that the usual paraxial theory for the Hermite Gaussian or Laguerre Gaussian beams, produced by some lasers, can be replaced by a more general theory which is precise according to Maxwell's equations. In this theory the beams exhibit an amplitude distribution over any plane normal to the direction of propagation which can be described using prolate spheroidal wave functions. As the degree of collimation is increased, these beams asymptotically take on the familiar Gaussian amplitude cross section. However, as the divergence from focus is increased, these beams asymptotically approach modified dipole fields. It is found that two, mutually exclusive, classes of beam fields exist. For each beam in one class there is always a complementary beam in the other class. As the degree of collimation is increased, complementary beams become almost identical. Complementary beams contain electromagnetic components which are related to one another in the same manner as between the fields of similar electric and magnetic multipoles.

ISSN:0030-3909    

DOI:10.1080/713818856

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Bragg diffraction of light by a standing sound wave is described. The frequency spectrum and the harmonic components of the diffracted and the undiffracted beams are obtained. These results cannot be obtained by superposing the diffraction effects due to the two travelling waves that make up the standing wave—not even when the acoustic power is low. Successive Bragg diffraction by two identical but oppositely travelling sound waves is also considered. It is shown that ‘simultaneous’ and ‘successive’ Bragg diffraction yield the same instantaneous irradiance of the diffracted and the undiffracted beams in the limit of low acoustic power ; however, the frequency spectrum of the undiffracted beams is always different in the two cases.

ISSN:0030-3909    

DOI:10.1080/713818857

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713818862

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Attention is drawn to possible inconsistencies in the familiar asterisk notation for convolutions and a simple alternative notation is proposed.

ISSN:0030-3909    

DOI:10.1080/713818859

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713818861

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor