Study Of Phase-Shifting Interferometric Digital Holography

Phase-shifting interference digital holographic microscopy is a new technology developed in recent years for the microscopic imaging of tiny objects combined with digital technology.It is a hot spot in the field of optical measurement.It mainly uses a photosensitive device(such as CCD,CMOS,etc.)to replace the traditional optical holographic dry plate to record the holographic image of the sample to be tested and store it in a computer,and then use a specific mathematical algorithm to process it accordingly,and calculate the The three-dimensional shape of the sample is measured and numerically reproduced in a computer to achieve microscopic imaging of the sample to be tested.This method has been developed in many fields such as shape detection,nanodevice detection,biological observation,particle field analysis,etc.due to its fast speed,full field quantitative,non-contact,real-time,and no special treatment of samples.The more applications.The basic idea of phase-shifting interference digital holography is to obtain several phase-shifting interference holograms by recording the phase difference between the reference lights by adding phase shifts in the reference light during the holographic interference process,and then recording them on the computer.The corresponding numerical algorithm is used to reproduce the complex amplitude distribution of the object light field,so as to achieve the purpose of phase reconstruction and three-dimensional microscopic imaging.The phase shift method can eliminate the interference problem of the twin image and the zero-order image during the holographic reproduction process,and improve the quality of the reproduced image.This thesis focuses on the construction of an practical digital holography system,focusing on phase-shifting interferometric digital holography,and has completed the following research work:1.This thesis reviews the generation and development of phase-shifted digital holography.The existing main microscopic measurement techniques are introduced and their respective characteristics are analyzed and compared.The reason for the phase shift digital holographic microscopy is introduced.The characteristics and current research hotspots of phase-shifted digital holography are introduced and analyzed.The basic knowledge of phase-shifted digital holography is introduced,including the concept of phase shift and the basic principle of phase-shifting interference,which provides basic theoretical support for subsequent research.2.The polarization phase shift method and the wave plate combined phase shift method are studied.The system composition and basic principle of the polarization phase shift method and the wave plate combined phase shift method are introduced.The four-step phase shift digital holography system is designed by using these two phase shift methods respectively.A digital phase shift holographic optical path system was actually built.Using a microlens array as a sample,an interferogram was acquired and processed.The residual phase of the system was analyzed.The method of eliminating the residual phase of the system is introduced.The phase reconstruction of the microlens array is completed.The results of the two algorithms were compared.3.Two-step phase-shifting algorithm is studied.The current research progress of traditional two-step phase shifting is introduced in detail,and its advantages and disadvantages are analyzed and sorted out.Combining the advantages of two-step phase-shifting algorithm and the special properties of optical transfer function,a new two-step phase-shifting algorithm is constructed.The theory of this algorithm is introduced.The effectiveness of the system is simulated and verified by using MATLAB software.The optical system is built for experimental verification.The phase reconstruction of the microlens array is accomplished by experiments with the microlens array as the sample to be measured.The characteristics are summarized and analyzed.This method can achieve the same phase reconstruction effect as four-step phase-shifting and save half the time.4.The synchronous phase-shifting algorithm is studied.The phase shifting principle of spectroscopic prism is introduced in detail.A new synchronous phase-shifting algorithm is constructed by combining the two-step phase-shifting method mentioned above.And its basic principle is introduced.The experimental light path is preliminarily built for verification.And the problems in it are analyzed and studied,and the simulation verification is carried out by using MATLAB software.Then the optical path is improved.The microlens array is used as an object to be measured for experimental verification.The experimental results are analyzed and improved.