Research On The Microscopic Technique Of Split Amplitude Common Path Off Axis Digital Holography

Owing to its label-free,non-contact,wide field and high accuracy,digital holography becomes one outstanding quantitative phase imaging technique and a powerful tool for measurements of biological samples,life science and microstructures.Traditional digital holography(DH),being non-common path geometry in nature,suffer from several problems:time-varying phase noise due to vibration and air flow,which deteriorate the stability of DH.The object and reference beams propagate along the same path in common-path configuration,the environmental disturbance and optical device’s distortion can be effectively compensated.However,common-path configuration still has some issues,including a complicated system structure,interference fringes with low contrast,low resolution reconstruction.The development of off-axis digital holography is restricted.The subject "common-path off-axis interferometric quantitative phase microscopy base on amplitude-division" is to study novel common-path DH with high stability base on commonpath interference,amplitude-division and point diffraction,which is highly stable and can improve the visibility of the interferogram.Then,the Fourier transform method,zero filling method and upsampling interpolation method are used to achieve high-resolution phase reconstruction.These works provide new theories and methods for the research of off-axis DH with high stability and simple.This subject has important application value in 3D topography measurement such as biological samples,steps,and resolution plates.The research content of this subject is summarized as follows:(1)The evolution and fundamental theory of off-axis digital holography are studied,and the benefits and drawbacks of the available technologies are analyzed.Afterwards,existing reconstruction algorithms are simulated and the benefits and drawbacks of traditional off axis digital holographic phase reconstruction algorithms are discussed.These works provide a fundamental theoretical framework for following research.(2)To establish a collecting system with strong stability,rapid speed,low complexity,and high hologram quality,a common-path off-axis interferometric quantitative phase microscopy base on amplitude-division is presented.The phase can be retrieved through a Fourier-transform based division method.The feasibility of the proposed structure was verified through phase plate experiments,which resulted in a measurement error of 0.83%.The system exhibits high stability and repeatability,with a stability deviation of 4.95 nm and a repeatability deviation of4.30 nm.To test the proposed system’s microscopic ability,onion epidermal cell experiments and red blood cell experiments were conducted.(3)A high resolution off-axis digital holographic imaging base on multi-level derivative spectrum fusion is proposed to reduce the interference of zero-order images on real image reconstruction and improve the resolution of the reconstruction results.The article describes how the real image spectrum was replicated using spatial interpolation and image fusion technology to achieve high-resolution reconstruction of the tested sample.The resolution was tested to be 128lp/mm through resolution board simulation experiments.The proposed algorithm was further tested for high-resolution performance using resolution board experiments,fruit fly wing experiments,and pumpkin slice experiments.