Reasearch On Speckle Suppression Of Digital Holographic Microscopy Imaging Based On Rotating Double Diffusers

With the development of digital holography,how to get high quality reconstructed image has become a very important problem in the research and application of digital holography.Because of the high coherence of laser as a light source,speckle noise is considered to be one of the urgent problems in coherent imaging.In the experiment of digital holography,the existence of speckle noise covers up some fine structures of micro objects,which will greatly affect the quality of reconstructed images.In this paper,a speckle suppression method based on the rotating double diffusers is designed.A series of non-coherent holograms are obtained by rotating the double diffusers to suppress the speckle noise.This method is simple,easy to implement,and improves the imaging quality of the reconstructed image.On the basis of single diffuser and the moving-static double diffusers to suppress speckle,the method to suppress speckle noise by rotating double diffusers is analyzed theoretically.Through the theoretical and simulation analyses of time-space correlation function for rotating double diffusers,the moving-static double diffusers and single diffuser,their uncorrelated periods and decorrelation rates are compared.It can be seen that the effect of rotating double diffusers is obviously better than the other two methods,which provides a theoretical basis for the experiments.The speckle suppression system of digital holographic microscopy imaging based on rotating double diffusers is designed.According to the design requirements and parameters,the key devices are selected and the system parameters such as transverse resolution and field of view are analyzed.The software flows of the system are described,and the software functions of hologram recording,hologram numerical reconstruction and speckle suppression results analyses are introduced.The research on experiments of digital holographic microscopy imaging with rotating double diffusers are carried out,including the calibration experiment of system transverse resolution,the speckle suppression experiments of manual rotating diffusers and the speckle suppression experiments of automatic rotating diffusers.By comparing with average value and standard deviation,the experimental results show that the speckle suppression effect of rotating double diffusers is better than that of single diffuser.The speckle suppression method of automatic rotating double diffusers provides a new idea for the speckle noise suppression of digital holographic imaging,which can be used in dynamic measurement applications such as vibration and biology.