Dynamic Imaging Based On FINCH System And Meta-holography Color Imaging

Holography,which is the most promising method for 3D display,can perfectly reconstruct both amplitude and phase information of the original object.It includes digital holography,computer generated holography and other mainstream research fields.Fresnel incoherent correlation holography（FINCH）,as a branch of digital holography,has strong stability,high resolution,fast imaging speed and other characteristics.However,the traditional FINCH needs to load different phase masks on the spatial light modulator（SLM）and record at least three times to obtain a clear reconstruction image,that limits its application in dynamic imaging.How to record multiple interference patterns and reconstruct the original object with high quality through single-shot has become a hotspot in FINCH system.SLM,which is the main device in FINCH system,also plays an important role in computer generated holography.However,most of the SLMs can only modulate the phase or amplitude singly,and the reflective working mode is not conducive to the compact optical path and device integration.In addition,the use of micron-sized pixels for holographic display in the visible light will cause various interferences.As an emerging direction in the 21st century,meta-holography devices have ultra-thin and flat configurations,smaller unit structures than the wavelength of light and larger field of view.It can also avoid the interferences caused by SLM in principle.These advantages above make meta-holography attract much attention of scholars.Current researches based on meta-holography mostly focus on achieving tunable imaging results.While in display field,the color information is also important.There are few researches on how to use the polychromatic incident light to achieve color imaging.This study focuses on how to realize real-time recording and dynamic reconstruction of holograms by single-shot without changing the traditional FINCH system.Use all dielectric materials to design the color phase modulation unit of the metasurface,improve the GS（Gerchberg-Saxton）algorithm in a targeted manner and finally simulate the meta-holography color imaging:1.Dynamic imaging based on FINCH system.On the basis of the traditional FINCH optical path,only by changing the phase mask,realize the single-shot FINCH technology,and compare its imaging results with the traditional methods.Result shows that its imaging quality is close to three-step phase-shifting technology and better than two-step phase-shifting.Use two experimental objects with different motions to record their dynamic imaging experiment.And the experimental results are analyzed,which proves the feasibility of single-shot FINCH technology.2.Metasurface simulation and improvement of GS algorithm.The unit of metasurface is designed using Si O₂ and Ti O₂,and several devices are simulated withπ/4 as the phase modulation interval.According to the corresponding relationship between the phase modulation and transmission,two targeted improvement methods are proposed for the traditional GS algorithm,and the imaging results are compared.3.Meta-holography color imaging.Use all dielectric materials to design the unit with color filtering and phase modulation features,and calculate its performances.Then,a color array is designed according to the transmission difference of units.Finally,use the improved GS algorithm to simulate the meta-holography color imaging.