Research and application of digital holography in the real-time dynamic measurement and the information hidden in the
|School||Nanjing Normal University|
|Keywords||Digital holography One-shot phase-shifting digital holography Graphic processing unit Polarization-multiplexing Large capacity informationhiding Double random phase encoding|
Digital holography acquires the digital hologram with CCD which is stored and numerically reconstructed by computer. Attracted more attentions by reseachers worldwide, Digital holography has many advantages such as low cost, fast capture speed, flexible record and reconstruction method and convenient transmission which is applied in many domains such as microscopy observation, micro-disform measurement, particle flow detection, target recognition and information hiding. But several key problems such as enhancing the quality of reconstructed image, acceleration of the reconstruction calculation, real-time measurement of dynamic process of the object, real-time reconstruction view and large capacity digital hologram hiding shoule be deeply studied. From the point of how to realize the dynamic process real-time measurement of the object and large capacity information hiding by digital hologray, The main innovation points are listed in the below:1. According to existing phase-shifting digital holography methods, a new method of phase-shifting digital holography based on the interference between two circle-polarized beams is presented, where the phase changes depend on the rotated angle of polarizer. Optimized parameters are obtained for good quality of reconstructed image with theoretical analysis and numerical simulation, where optical experimental results demonstrate this technology can effectively remove the zero-order and conjugated image and acquire good-quality reconstructed image.2. One-shot four-step phase-shifting digital holography based on periodic polarization distribution instead of periodic phase array in space domain is presented where no precise alignments between phase array and CCD are needed and the experimental difficultites are greatly reduced. Reconstruction algorithms of compound hologram are studied with interpolation calulation and the same results are obtained between optical experiments and theoretical simulation. The feasibility of one-shot phase-shifting digital holography is demonstrated with experimental results which can provide the brand new measurement method and high performance detection scheme in dynamic process such as cell diagnose and plasma analysis.3. According to the deficiency of CPU in parallel computation, the accelerated calculation software based on GPU is designed with Matlab code with obvious acceleration speed and high efficiency. According to the real-time characterization of the dynamic process, the powerful real-time reconstruction view software is designed including real-time recording, accelarted calculation and real-time display three functions compiled with C#codes and.Net platform. With this tool, the dynamic process of the3D object rotated by1Rpm are studied and the display speed can get21frames per second, which can provide the software ensurement and technology support in real-time characterization of dynamic process such as cell diagnose and plasma analysis.4. According to the information hiding method of complexed image embedded in the space domain, a new complex value information hiding technology is presented with DCT and Double Random Phase Encoding and optimized embedding coefficient is obtained by comparing the invisibility of the host image and the quality of the extracted hiding image under different embedding coefficients. The attack results indicate3D object phase-shifting digital hologralm as hiding information and the information embedded in the DCT domain have better anti-attack effects and robustness.5. From the need of large capacity information hiding, two large capacity digital holography schemes are presented based on polarization-multiplexing and waveleng-multiplexing tecnologies. The attack effecs are compared in two polarization-multiplexing digital holograms with and without phase shifting. The results indicate two schemes can enlarge the hidden information capacity, skillfully solve the problem of more embedded information in limited redundant information of host image and have better anti-attack effects with phase-shifting digital hologralm as hiding information.