| Simultaneous acquisition of multiple complex wavefronts is of great significance for realtime study of dynamic events.Single-shot optical imaging methods based on multi-channel multiplexing digital holography can capture multiple complex amplitude wavefronts of dynamic scenes in a single camera exposure.Compared with the traditional single-shot intensity imaging methods,single-shot multiplexing holographic imaging methods can accurately reconstruct the complex amplitude distribution of multiple wavefronts based on the principles of interference recording and diffraction reproduction imaging,which has the advantages of real-time,label-free,quantitative phase measurement,etc.The single-shot multiplexing holographic imaging methods are widely applied in field of view extension,ultrafast laser pulse and matter interaction,optical diffraction tomography 3D microscopic imaging,etc.This dissertation mainly focuses on the different implementations of single-shot multiplexing holographic imaging,and corresponding theoretical analysis,system construction,and application in ultrafast imaging and 3D diffrachtion tomography.In this dissertation,four types of single-shot multiplexing holographic methods are proposed to investigate and achieve the large field of view,high-integration,multi-dimensional multiplexing holographic imaging system.The important research results are summarized as follows:1.Based on multi-channel angle-division multiplexing holography,a single-shot ultrafast holographic recording method with a large field of view and high time resolution is proposed.The walk-off effect caused by the short coherence of ultrafast laser pulse in traditional off-axis digital holography has been effectively resolved.This simplifies the interference adjustment process about aligning the object and reference beams.In this method,a sequence pulse generation and delay control unit,which includes a set of diffraction gratings,is designed and constructed to simultaneously generate zero-order diffraction probe pulse sequences and high-order diffraction reference pulse sequences required for angle-division multiplexing holographic recording.The role of gratings in modulating the pulse front is analyzed,as well as the theoretical description of diffraction grating-based sequential pulse generation and delay control unit and angle-division multiplexing holographic imaging unit is given.The air plasma induced by a single femtosecond laser pulse is quantitatively measured using an established experimental system.The experimental results demonstrate that the proposed method has high temporal resolution by recording and reproducing the space-time evolution of plasma at the pico-to femtosecond order.2.A simple single-shot ultrafast holographic recording method based on multi-channel spacedivision multiplexing in-line holography is proposed.This method not only simplifies the singleshot ultrafast holographic imaging optical deviced but also avoids the problem of time resolution reduction caused by the sub-pulse broadening.In this method,a designed micro-reflection delay array is combined with the principles of Gabor digital holography.The former generates a set of array sub probe pulses that can be adjuseted independently in terms of propagation direction and time delay thtough intensity segmentation.All the sub probe pulses illuminating sample are distributed in different regions of the recording plane without interference.The imaging geometry of the Gabor holography ensures the simplicity and stability of the optical path.Theoretical analysis and description of space-division multiplexing in-line holography are presented,along with a proposed improved in-line phase reconstructed algorithm.The dynamic evolution process of air plasma induced by a single femtosecond laser pulse is measured using the established system.The experimental results also maintain a time resolution of femtosecond order,which verifies the feasibility of this method.The refractive index distribution of air plasma is reconstructed by Abel inverse transformation,and the results are consistent with those of existing studies.3.Based on the existing sequential pulse generation and time-delay control unit,a single-shot multi-depth microscopic imaging method with large field of view is peoposed.It can effectively solve the problem of reduced field of view due to high axial resolution in the single-shot multidepth imaging system based on the traditional low-coherence off-axis digital holography.The integrated and modular design of a sequence pulse generation and delay control unit is conducted,resulting in the development of an integrated sequence splitting module unit with excellent stability and flexible delay control.The key optical components’ parameters in the sequence splitting module unit are comprehensively analyzed,such as the relationship between sub-pulse intensity,beam splitter parameters,and unit sequence depth.It also investigates how the diffraction efficiency of various grating types affects holographic interference fringes.Quantitative imaging was conducted on three USAF resolution plates with varying depths and dispersed plane positions.The reconstruction results provide the contour distribution of each layer pattern,and the relative position of each layer can be calculated by utilizing the known reference beam path difference.4.A novel multi-channel space-angle division dual-multiplexing holographic recording method based on microlens array is proposed.The method combines the principle of traditional single-shot multi-wavelength holographic imaging based on angle-division multiplexing with the principle of existing single-shot single-wavelength optical diffraction tomography based on microlens array multi-angle illumination and space-division multiplexing recording.Single-shot multi-wavelength optical diffraction tomography can be achieved by illuminating with a broadband light source.The theoretical analysis focuses on the propagation direction of an illumination beam through a microlens array at various incident angles.The space-angle division dual-multiplexing holographic recording method is described in detail,and the theoretical analysis of the system is conducted.A method is proposed to reconstruct the 3D refractive index of samples at multiple wavelengths from a single space-angle division dual multiplexing hologram.The static polystyrene microspheres and living C.elegans were quantitatively measured by the system,and the 3D refractive index distributions at three different discrete wavelengths were reconstructed,and their refractive index dispersion characteristics were further calculated. |
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