Research For Digital Holographic Tomography Reconstruction With Few—View Date

Digital holographic tomography(DHT) is a new technique emerged few years ago, it obtains scattered field date from different views by digital holographic microscopy(DHM), and then calculates the3D(Three-dimensional) distribution of refractive index of sample by optical diffraction tomography algorithm. It can efficiently reconstruct the3D refractive index of some tiny samples such as biological cells or micro-optics, and it is promising in life science-. Materials Testing and some other areas.Optical diffraction tomography requires scattered field date from many different views to reconstruct the object function. There are two commonly used ways to acquire the scattered field date from different views. One is changing the direction of incident light with sample fixed; The other one is whirling the sample with direction of light unchanging. Howerer, no matter which one is used, it will cost long time to record holograms from large number of views. This is the key factor that limits the application of DHT. In this artical we propose a frequency-iterative regulation method based on the research of DHT. It combines regulation method and fourier mapping method, and achieves the purpose of regular iteration with light diffraction taken into consideration. The results of both numerical simulation and experiment show that our method is effective in DHT reconstructing with few-view date.Our article is consist of these following sections:In section one we firstly summarized the development of DHT, including DHM and tomography, then introduced the present research status of DHT. On this basis, we analysised the key problems existed in DHT at present, then proposed the research priorities of this article.In section two we introduced the basic principle of DHT at first; and then discussed two typical reconstruction algorithms—filtered back projection algorithm(FBP) and diffraction tomography algorithm, also introduced the application of these two algorithms in DHT. At last we compared these two algorithms. Because FBP is based in the premise that light transmits through object linearly, and ignore the problem of diffraction, its reconstruction accuracy is lower than diffraction tomography algorithm.In section three we did some research on tomography algorithm which only needs few-view date, proposed a frequency-iterative regulation method, which combined regulation method and fourier mapping method, achieved the purpose of regular iteration based on few-view date with the light diffraction taken into consideration. We used edge-preserving regular constraint, and added positive constraint to the iterative process in order to improve the accuracy of reconstruction. At last we tested and verified the feasibility of this algorithm. Numerical simulation confirmed the effectiveness of this method used in reconstruction with few-view date.In section four we did experiment reasearch on DHT reconstructing with few-view date based on the research of theory and algorithm. We set up a system of DHT with the structure of whirling the sample. We uesed polarization maintaining fiber and photonic crystal fiber to test respectively, recorded holograms with objective light illuminating from different views, and calculated the corresponding scattered fields date. We reconstructed the internal refractive index of optical fiber with few-view date by our method,and achieved the nearly same result as fourier mapping method with full-view date. The result of experiment showed that our method was efficient in DHT reconstructing with few-view date.In section five we proposed a summary and outlook, summarized the work we have done in this artical and put forward the problems that should be done in our future work.