Measuring Research Of Micro- And Nano-scale Geometry Based On Digital Holographic Microscopy

With the characteristics of high precision,non-contact and real-time measurement,digital holographic microscopy(DHM)has become a significant optical technique in measurement of micro-scale or nano-scale geometry.The resolution of DHM can be micro-even submicron-scale in in-plane measurement and nano-scale in axial measurement.Therefore,DHM is widely applied in micro-and nano-technology,material science and life science.However,with the development in technology,the measuring requirements of smaller scale and higher accuracy are more and more demanded.Hence there is plenty of room to progress in measuring resolution,field-of-view and efficiency when DHM is used in micro-and nano-scale measurement.This paper focuses on the improvements in the three factors above by theory analysis and experimental testing.The main research is about,1.The principle and numerical techniques of DHM are analyzed.The digital image-plane holographic microscopy(DIPHM)is introduced as a special case of DHM,which can collect more information of the optical system.2.To improve the in-plane resolution,we use angular multiplexing method to synthesize aperture to achieve the super-resolution measurement.3.Signal-to-noise ratio is important to the axial resolution in DHM.Therefore,DIPHM is used to decrease noise in DHM.4.DIPHM is used to enlarge the measuring field-of-view of DHM to truly 100% full field-of-view.5.A novel method based on optical path length difference is proposed to apply in particle tracking.This method improves the efficiency of classical DHM.The measuring limitation of classical DHM is avoided by using this method.6.The experimental setups according to the tested samples are developed based on the principle of DHM.With the experiments on micro-and nano-scale structures,living cells and particles,the DIPHM is proved to be a technique with truly full field-of-view and low noise level.The optical path length difference method is also demonstrated to improve the measuring efficiency of DHM.