Research On Digital Holographic Microscopy Technology Basing On Hilbert-Huang

According to the difference separation of zero-frequency component,real image and conjugate image in the spectral domain,digital holography can be divided into on-axis,off-axis and slightly off-axis technology.And among them,off-axis digital holography has been widely favored in the field of real-time three-dimensional quantitative measurement because of its single-time exposure imaging.However,due to the interference of the zero-frequency component,the resolution of the off-axis phase image recovered by the traditional Fourier transform method is not high and the accuracy is limited;The phase image recovered by the phase-shifting method has higher resolution accuracy,but needs to acquire multiple images at the cost of time resolution or imaging field of view;Although image processing techniques such as wavelet transform can improve the quality of phase recovery,it is necessary to select wavelet bases and the like,and lacks adaptability.The existence of these problems makes digital holography unable to balance the quality and speed of imaging.Therefore,how to achieve high-resolution,adaptive three-dimensional imaging measurement in off-axis digital holography has important research value.In this paper,Hilbert-Huang technique is introduced to effectively suppress zero-order and noise interference in the phase reconstruction of off-axis phase diffraction phase microscopy system,which can not guarantee the phase recovery accuracy,computational efficiency and adaptability at the same time.Based on an off-axis hologram,phase resolution and adaptive reconstruction are realized,and then refractive index measurement such as organization is completed.The main contents of this article are as follows:Firstly,according to the basic principle of phase recovery of off-axis digital holography technology,two-dimensional empirical mode decomposition is introduced by its spectral characteristics,and an adaptive phase reconstruction technique based on fast two-dimensional empirical mode decomposition is proposed to achieve the suppression of zero-frequency components.The superiority of the method was verified by experiments and simulations,the reconstruction accuracy of the phase-shifting method can be approached only by a single exposure.Secondly,aiming at the time-consuming problem in the process of two-dimensional empirical mode decomposition,based on the characteristics of digital holographic image,the fast method is further improved.Combined with the Hilbert spiral transformation,an adaptive phase reconstruction technique based on improved Hilbert Huang is proposed.On the one hand,it solves the time-consuming problem,and on the other hand,it improves the quality of the reconstructed image.Finally,the feasibility,rapid adaptability and universality of the proposed algorithm are verified by experiments and simulations.On the basis of quantitative phase imaging,the phase information obtained by the improved Hilbert Huang algorithm is combined with the spatial refractive index distribution to realize phase-based refractive index measurement under the premise of unknown sample thickness,and to extract medical specimen optics for the future.Characteristic information and information on obtaining tissue lesions provide new ideas.