Research On Dynamic Display Technology Of Digital Holographic Microscopic Imaging Based On Spatial Light Modulator

Holographic technology can completely record and reproduce all the information of three-dimensional(3D)objects.Digital holography technology uses optocoupler devices instead of traditional holographic materials to record the hologram of actual objects,and then through simulates optical diffraction by computer to realize the holographic reproduction of the recorded object,which has the characteristics of low cost and fast imaging.It has a wide range of applications in scientific research and production practice.However,what digital holographic reproduction only obtains is a digital perspective 3D image displayed on a computer screen,and does not form an optical image of the object in space,which is difficult to meet today's display needs.With the development of spatial light modulators(SLM)and computer science,digital holograms can be loaded into SLM for optoelectronic reproduction.Due to the low diffraction efficiency of digital holograms and the influence of factors such as recording process errors and SLM technology,display effect of digital holograms is not satisfactory.Using the liquid crystal spatial light modulator as the display device,this paper focused on how to improve the digital holographic display effect and realize the dynamic display of digital holographic microscopy imaging.According to the advantage of high diffraction efficiency of kinoform,a digital holographic photoelectric display method based on kinoform coding was proposed in this research.A high-speed camera was used to collect the digital holograms of the dynamic change of the micro-nano objects,and the dynamic display of the digital holographic microscopic imaging only under the action of the phase change was realized by the proposed method.This thesis involves following research contents:1.The basic theory of digital holographic microscopy,including the principle of recording and reproduction,the reasons for phases wrapping and unwrapping methods,and three digital holographic microscopy recording methods are deeply studied.The problem of secondary phase distortion in the pre-amplification holographic microrecording method is studied,and the method of eliminating phase distortion is introduced,which has guiding significance for the subsequent improvement of digital holographic imaging quality.2.The principles of SLM and three typical coding methods are studied,and the kinoform encoding with extremely high diffraction efficiency and no redundant diffraction images is used as the basis for subsequent research.The kinoform optimization algorithm is studied.Both the simulation results and the e_nms show that the algorithm can improve the display effect.The 3D display technology based on computer-generated hologram is studied,and different planes of virtual 3D objects are simulated and reproduced.Combining the advantages of digital holography and computer-generated hologram 3D display technology,a digital holographic optoelectronic display method based on digital kinoform coding is proposed.The 3D reconstructed image of digital holography is used as the input information,and the kinoform coding and optimization algorithm are used to load it onto the SLM to realize the dynamic holographic optoelectronic display of the actual 3D object.This method is extended for dynamic objects that only focus on changes in phase information.3.The principle of eliminating secondary phase distortion by same curvature object reference light is expounded,and the accuracy of the method is verified by experiments.The holographic interference method is studied,and it is proposed that the combination of single exposure method and high-speed camera can record the digital hologram of dynamic objects and avoid the error caused by phase unpacking.The dynamic digital hologram microscopy experiment was carried out on the MEMS microphone by same curvature object reference light and single exposure interferometry,and the phase information obtained by the digital hologram was compared with the results measured by the Doppler interferometer in Germany,and the relative error was 4.52%,which proved that a high-quality digital hologram was obtained,which provided data support for the subsequent dynamic digital hologram microscopy display experiment based on SLM.4.The influence of the pixel structure of the liquid crystal space light modulator(LCOS)was studied,and the interference was eliminated by loading digital grating and digital lens.The phase modulation characteristics were studied,and the display effect was improved by using gamma correction.A display system based on LCOS is built,and the digital holographic dynamic display method proposed in this paper realizes the dynamic display of digital holographic imaging of micro and nano objects.