Structured Illumination Imaging Technique Based On Rochi Grating

Phase distribution is essential when measuring the surface shape and the details of sample in an optical diffraction system.Therefore,the calculation of phase retrieval is a focused issue in the field physics.The core of phase retrieval problem is reconstructing the complex amplitude of objective optical field through the measured amplitude information.Holographic or iterative diffractive method both can achieve the reconstruction.Especially iterative phase retrieval algorithm,because of its simple optical installation,has raised more and more attention.The phase retrieval algorithms proposed in recent years have innovation in the aspect of scanning mode or constraint settings.But changing the illumination pattern in phase retrieval system has not been studied widely.Hence the main research content is to introduce structured illumination into phase retrieval system,which is called structured illumination imaging based on Ronchi grating.The main research contents are as follows:Firstly,imaging optical path is designed and the principle and process of imaging system are analyzed.The parameter and position of optical element are arranged.After studying the character of Ronchi grating,the similarities and differences between Ronchi grating and sinusoidal gratin,the paper discuss es how the Ronchi grating modulates the illumination structure.Then the imaging system proposed by this paper is simulated.According to the result of simulation,the accuracy and speed of reconstructing image are analyzed.In order to get a better test of this image system,a recently presented method called in-line holography with Talbot grating illumination is used to be compared with.Secondly,the factors which influent the quality of imaging system are analyzed,including wave length,inclined diffraction,grating character s and axial direction diffractive distance.The grating characters include grating modulation,grating position and grating periods.Using various simulation parameters,how these factors affect imaging result is discussed.The optimal range of these parameters is selected from the analytical results to reduce the influence.Therefore,the influences are amended to get a better reconstructed image.Finally,the experimental system is set up to validate the proposed imaging system and method.Under the conditions that experimental equipment and the environment allowed,the appropriate parameters are selected.The correction of the inclined illumination is carried out to obtain better experimental results.After the images are collected in the experimental system,the algorithm is verified and the experimental results are analyzed.