A Study Of Theory And Application On Periodic Structure Imaging

In recent years, since the importance of it in the fields of optics,electronic diffraction, electronic microscopy and optical communication,ones pay their attentions to diffractive characteristic of periodic structure.Diffractive characteristic of period objects were analyzed and generalizedby the photonics method. The photonic Fraunhofer diffraction at a annularaperture or a ultrasonic grating be explained from probability wave inquantum theory, the same conclusion with Huygens-Fresnel principle orFourier transform be obtained.Talbot effect is explained with the viewpoint of photonics, the sameconclusions to positive self-imaging, negative self-imaging and fractionimaging with Huygens-Fresnel principle or Fourier transform be obtained.The adjustable coefficient q for Talbot-effect is advanced, its actions forpositive self-imaging, negative self-imaging and fraction imaging, as wellas the phase relations between the object and the image be discussed.The self-imaging process is discussed in spatial-frequency domainwith Wigner transform function. Unified explanation of the effects due toTalbot and Montgomery effect is presented in spatial-frequency domain.Diffractive characteristic of periodic structure objects were analyzedand generalized by the principle of the recordation and reappearance forspatial information of object by photons. Ordinary Moiréeffect can beregarded as the limit of the coherent Moiréeffect. At the same time, thedirection of Moiréspatial frequency, spatial period of Moiréfringe andthe step of the measuring grating be given with the method used. Being itssimplicity in mathematics, the method suggested is easy to use widely,especially in the fields of information.When a periodic object with subwavelength structure be illuminatedby normal incident monochromatic light-beam, evanescent waves canoccur. Bing attenuated quickly, the object with subwavelength structurecan not be imaged by ordinary method. However, one-dimensionalperiodic object with sublambda structure can be corded by a grating sothat homogeneous waves can be obtained. Passing through the optics system designed specially, the well-distributed waves with evanescentwaves be enlarged so that it can be recognized by CCD camera. After that,the homogeneous waves with evanescent waves be decoded by a decodinggrating. By decoding, the information of encoding grating is filtered, theimage of the object with subwavelength structure can be reappeared in theimage plane. The imaging technique based on the conventional opticssetup is a novel technique, by that, superresolution image of object withsubwavelength structure can be obtained. Theoretical analysis of theimaging process for the object with subwavelength structure be given wellby photonics method. It be designed that where the encoding grating andthe decoding grating are placed, so does how to choose the tilt anglesbetween the two gratings and the object. At the same time, it be discussedthat the low pass filters used in the novel technique also. The results ofexperiment demonstrate that the theory which used is valid. Theoreticalanalysis and experimental design for the imaging process oftwo-dimensional object with subwavelength structure be also given byphotonics method.