Research On Dynamic Object Reconstruction Technology Based On Dual-Wavelength Digital Holographic Microscopy

Comparing to other traditional microscopy,digital holographic microscopy(DHM)has the advantages of being full field,high resolution,real-time,non-contact,etc.It can be widely used in the contour measurement,biomedical imaging,stress testing,spatial particle image velocimetry and other fields.The depth of measurement is proportional to the laser wavelength.Therefore,a dual-wavelength digital holographic microscopy that synthesizes a greater equivalent wavelength with two different wavelengths can obtain a larger depth profile and a wider application range.In this thesis,a dual-wavelength digital holographic microscopy with high-speed camera technology improves the temporal resolution of hologram capture,and controls the phase difference in the wavelength range.It can avoid the phase unwrapping operations,reduce errors,and improve reconstruction efficiency.The digital holograms of dynamic objects is recorded in real-time.The GPU(Graphics Processing Unit)technology is introduced to perform the multi-stream reconstruction processing for improving the real-time performance of dynamic measurement.The contents of this thesis are as following:(1)Basic theories of the dual-wavelength digital holography microscopy including the principle of digital holography recording and reconstruction are introduced.The selection of amplification methods,the aberration correction technique and the phase unwrapping methods are discussed.(2)To verify the validity and accuracy of dual-wavelength digital holography,the numerical simulation and the optic experiments were conducted.The system of the off-axis dual-wavelength digital holographic microscopy was built to capture holograms of the small depth profiles,transmission-type objects and reflective-type objects respectively.The experimental results were in good agreement with the standard values,which showed the method can directly acquire the higher quality phase distribution for object.(3)A dual-wavelength digital holographic microscopy system with high-speed camera and GPU was proposed to observe the dynamic object.The deformation of the MEMS microphone was measured successfully by this system.The results showed that the phase change of the MEMS microphone is consistent with the input signal,which demonstrated that the proposed system is suitable for measuring of dynamic targets in real-time.(4)The digital holographic microscope in transmission mode was fabricated.The software systems were developed,and then we observed the onion cell by this system.