摘要:

The use of a moving, random aperture in the plane of a hologram has been recently suggested for reducing speckle in the reconstructed image of a diffusing object. A theoretical analysis shows that while the attenuation of the power spectrum of the speckle is proportional to the square of the average transmittance of the random aperture, the power spectrum of the signal is also attenuated by the same factor, resulting in a loss of image contrast. Because of this there is no overall gain. Some experimental results are presented which support these conclusions.

ISSN:0030-3909    

DOI:10.1080/713818950

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713818945

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A new view of the problem of continuing a given segment of the spectrum of a finite object is presented. Based on this, the problem is restated in terms of reducing a defined ‘error energy’ which is implicit in the truncated spectrum. A computational procedure, which is readily implemented on general purpose computers, is devised which must reduce this error. It is demonstrated that by so doing, resolution well beyond the diffraction limit is attained. The procedure is shown to be very effective against noisy data.

ISSN:0030-3909    

DOI:10.1080/713818946

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713818948

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The frequency responses of eight apodized systems with circular aperture have been investigated. The apodization has been done by dividing the aperture into two and three rings of different areas either by using a π -phase distribution or by amplitude transmittance variations in the different rings. It is found that the response of the system can be improved in any desired range of frequencies by selecting its special form, its obstruction ratios and transmittances in the different rings, as the case may be.

ISSN:0030-3909    

DOI:10.1080/713818943

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/716099348a

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713818940

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713818951

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713818947

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713818952

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor