Optical data-processing is generally considered to have begun with Abbe's theory of image formation in the microscope. Since then the subject has expanded greatly until at this point in time it includes a plethora of techniques ranging from the simplest one-lens Fourier analysers and multipliers through coherently and incoherently illuminated correlators and processors to electro-optic devices and computer processing of optically logged data.
To review the complete range of techniques and applications adequately is not possible within this article which is restricted, therefore, to a discussion of optical imaging techniques employing coherent illumination that are designed to process the input signal by the inclusion of masks and spatial frequency filters that control the system transfer function. Emphasis will be put on the characteristics of those spatial frequency filters and the processed images produced with them. The article will introduce the basic theory of coherently illuminated optical systems in terms of the Fourier transform relationships that exist between specific planes of those systems, including a discussion in general terms of the influence of masks and filters on the imaging characteristics of those systems. The major portion of the article will present a detailed examination of the properties of specific spatial frequency filters. They will be discussed firstly under a classification of filter types where their individual data processing characteristics will be elaborated and then, in summary, they will be reviewed within a classification of data processing function. Finally an appendix is included which further elaborates the theory of coherently illuminated optical systems, detailing the exact relationships between the complex amplitude distributions occurring in the principle and other planes of such optical systems.
Source : http://www.iop.org/EJ/abstract/0034-4885/35/3/305
To review the complete range of techniques and applications adequately is not possible within this article which is restricted, therefore, to a discussion of optical imaging techniques employing coherent illumination that are designed to process the input signal by the inclusion of masks and spatial frequency filters that control the system transfer function. Emphasis will be put on the characteristics of those spatial frequency filters and the processed images produced with them. The article will introduce the basic theory of coherently illuminated optical systems in terms of the Fourier transform relationships that exist between specific planes of those systems, including a discussion in general terms of the influence of masks and filters on the imaging characteristics of those systems. The major portion of the article will present a detailed examination of the properties of specific spatial frequency filters. They will be discussed firstly under a classification of filter types where their individual data processing characteristics will be elaborated and then, in summary, they will be reviewed within a classification of data processing function. Finally an appendix is included which further elaborates the theory of coherently illuminated optical systems, detailing the exact relationships between the complex amplitude distributions occurring in the principle and other planes of such optical systems.
Source : http://www.iop.org/EJ/abstract/0034-4885/35/3/305
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