Imaging Characteristics And Application Research Of Fresnel Incoherent Correlation Holography

Incoherent light is used by Fresnel incoherent holography(FINCH)imaging systems to complete the holographic recording,and then the interferograms are reconstructed by computer algorithms.The traditional FINCH imaging system has the characteristics of super resolution imaging,but there are interference of twin image and zero-order term in its reconstructed image,which will lead to image blurring.A clear image can be reconstructed after linear superposition of holograms by using the three-step phase-shifting technology,it means that the test object of multiple shots is almost stationary,so this technique is not suitable for real-time imaging of living cells and moving objects.In order to improve the recording speed of this system,two-step phase-shifting technology is introduced into the reconstruction process,but this method cannot remove those interference terms,and the quality of the reconstruction is poor.With the pursuit of imaging speed,the application of single-shot technology has become a research hot spot of holography.Therefore,the research focus of this paper is to propose a schemes to improve the main imaging characteristics of the image based on two-shot and to realize the single-shot technology in the microscopic system.(1)Study on the imaging resolution.This paper presents two methods to improve the resolution: two-step optimization algorithm and discrete wavelet transform.According to the interference theory to derive the two-step optimization algorithm,and the experimental results prove that this algorithm can not only improve the resolution of reconstructed images,but also eliminate the reconstruction algorithm progress.The second scheme is to use the theory of discrete wavelet transform to achieve the purpose.It is proved by experiments that this filtering method can also improve the resolution.(2)Study on the imaging quality.Noise has always been the main factor that affects the imaging quality.This paper introduces two denoising techniques based on traditional two-step phase-shifting technology.According to the background subtraction method theory,the corresponding surface mesh diagrams are drawn for a series of experimental data,and the objective evaluation is carried out to prove that this method can effectively remove the environmental noise.Then according to the concept and the expression of adaptive spatial averaging,the optimal number of merged pixels in the experimental system is found.The experimental results are compared with the commonly used filtering algorithms to prove its effectiveness.(3)The application of single-shot technology in FINCH microscopic system.Through the simulation of different objects,the suitable objects of two-step phase-shifting technology are studied.It shows that two-step phase-shifting technology has advantages in microscopic system.Based on the theoretical part of this article,the data show the role of background subtraction in single-shot FINCH microscopic imaging system.Then analyzing the resolution and the field of view of two plant cells.Finally,the recording of onion epidermis cells is carried out to demonstrate the feasibility of the single-shot method based on FINCH microscopic system.