New Quantitative Phase Microscopy Imaging Method And Its Application Based On Digital Holography

Digital holography,as an optical imaging technology,has the unique advantage of quantitative imaging and measuring the complex amplitude(especially the phase information)of the object wavefront and it has been widely used in many fields such as physics,chemistry,biology,medicine and so on.Recently,based on the traditional off-axis digital holography and in-line digital holography,slightly-off-axis digital holography and common-path off-axis digital holography have been developed.Compared with the traditional off-axis digital holography(such as the off-axis digital holography based on Mach-Zehnder or Michelson interferometers),the slightly-offaxis digital holography has the advantage of requiring less bandwidth of image sensor and less measurement than the traditional common-path digital holography.Compared with the traditional off-axis digital holography,the common-path off-axis digital holography has more stable structure,stronger anti-interference ability to mechanical vibration and air disturbance,and fewer optical elements,and it has been widely used in quantitative phase imaging and other fields.This paper focuses on the theory of quantitative phase microscopic imaging based on digital holography,especially slightly-off-axis digital holography and common-path off-axis digital holography and quantitative polarization micro-imaging based on common-path off-axis digital holography.The main research contents of the paper are as follows:1.The first chapter summarizes the historical background and research progress of phase microscopic imaging technology based on digital holography.It mainly introduces the research progress of off-axis holographic imaging technology and in-line holographic imaging technology,and introduces the slightly-off-axis holographic imaging technology and common-path off-axis holographic imaging technology developed in recent years.2.The second chapter makes a basic theoretical analysis of digital holography.Briefly introduces the basic theory of holographic imaging and the method of hologram reconstruction,focusing on the recording of off-axis digital holography and the reconstruction of off-axis digital holography.3.In the third chapter,the basic theory of polarization and the description of polarization characteristics of polarization sensitive media are briefly introduced.On this basis,the measurement method of polarization sensitive samples based on digital holography is analyzed theoretically.Based on the introduction of Jones vector,a common characterization form used to describe polarized light,the matrix form and operation method of common polarization devices are described and summarized,and the description of polarization characteristics of general polarization sensitive materials by Jones matrix description method is emphasized.At the end of this chapter,we introduce the Jones matrix measurement method of polarization sensitive samples illuminated by circular polarized light and linear polarized light.4.In the fourth chapter,a new method of off-axis digital holography is proposed,which can be used for quantitative phase imaging of large-scale objects(tens of centimeters)and small-scale objects(several microns).In this method,the converging spherical wave generated by a large-scale converging lens is used as the illumination source,and a special circular aperture is placed on the converging surface of illumination light(the spectrum surface of object wave).The reference light for holographic recording comes from the reference pinhole near the edge of the circular aperture of object light,and the required illumination light and coherent reference light source are generated by a 1 × 2 single-mode fiber beam splitter.This method has the advantages of low cost,simple optical path and strong anti-interference ability because of the use of single-mode fiber splitting and slightly-off-axis interference optical path structure.It provides a low-cost way to transform the traditional microscope into a high-resolution holographic quantitative phase microscope.5.In the fifth chapter,a double-channel polarization holographic microscope imaging method with simple structure and suitable for microfluidic environment is proposed.In this method,a specially designed three channel combined polarization microscope lens is used to realize the off-axis holographic recording and the digital reconstruction of the polarization information(such as the birefringent optical axis orientation and the birefringent phase delay of the sample).The structure of the micro fluidic polarization holographic micro imaging optical path designed by this method is simple,which greatly improves the stability and portability of the polarization imaging system,and provides a new feasible way for the development of the portable micro fluidic click polarization microscope imaging system.6.In the sixth chapter,a multichannel polarization holographic microscope imaging method based on fiber splitting and Wollaston prism is proposed.This method is based on the common-path off-axis digital holography structure,which can polarize the dynamic samples in the microfluidic channel and realize one-step measurement of Jones matrix of the dynamic polarization sensitive medium.In this method,only two optical fiber splitters,a Wollaston prism and a converging lens are needed to realize the four-channel angular multiplexing of hologram,which greatly reduces the number of optical elements.Moreover,due to the design of common-path off-axis design,the anti-interference ability of optical path to vibrations and misalignment is stronger.A four-channel polarization holographic imaging device based on this method is designed and fabricated by using 3D printing technology.The polarization imaging experiments of starch particles and nematodes in microfluidic channels are carried out by using this imaging system and the Jones matrix parameters are obtained successfully.The experiment verifies the practical feasibility of this technology.