Research Of Incoherent Digital Holography Imaging Experiment And Performance

Compared with the traditional imaging which can only record the amplitude information of the object,holography is an imaging method that records the amplitude and phase information of an object through the principle of diffraction and interference of light.Traditional holography requires the coherent light and photosensitive materials to illumination and recorded,and this can cause many problem such as speckle noise,complex light paths,tedious issues and so on.With the development of the digital sensors and computers and spatial light modulators,non-coherent digital holography has developed rapidly.Spatial light modulators and other technologies make the light source free from the dependence on the coherent light,solved the problem of speckle noise in imaging.The digital recording method has also facilitates the recording and reproduction of holograms greatly.In this paper,the application of telephoto imaging and the improvement of the system resolution are mainly studied based on the non-coherent digital holographic imaging system.The main content of the paper is as follows:Firstly,two common non-coherent digital holographic optical paths are introduced,one of the system is FINCH system based on a spatial light modulator and anthor is the coaxial holographic system based on a Michelson interferometer.For both systems,the point spread function and the recording process were derived based on the scalar diffraction theory;For the problem of the interference term occurring in the coaxial hologram,anlyzes the process to eliminate the interference term through the three-step phase shift and the general three-step phase shift method;The convolution method of Fresnel diffraction integral formula,Fresnel transform method,and angle spectrum method,three kinds of ways to reproduce holograms were introduced;Calculated the lateral magnification and reproduction distance of the two systems.Then prove the feasibility of the two systems and analyze the advantages and disadvantages of the imaging results based on the result of the USAF.Secondly,based on the two systems described in the first paragraph,a holographic imaging optical path of the front-end telephoto system was built,and theimaging process was analyzed in detail.For the FINCH telephoto system,a hologram of the USAF at a long distance was taken and reproduced;the NSR of the imaging result was optimized by adding a variable iris to limit the interference of stray light;Coins with different depths of space were photographed,and the three-dimensionality of the system was verified through clear reproduction of the coins by the different reproduction distances.For the Michaelson Telescope system,a hologram of the USAF and coin was taken and the clear reproduction was achieved,verified the feasibility of the telecentric system used in the Michaelson telescope system.Finally,the FINCH telephoto system is taken as an example to analyze the depth of field of the holographic telephoto imaging.The theoretical and experimental results verify that the system has the depth of field.Finally,to breakthrough the resolution of the optical systems,the principle of super-resolution of structured light is introduced.For the generation of the light source in the imaging process,the expression of the sinusoidal stripe structure light was given;For the algorithmic processing of recording holograms,the methods of frequency domain's separation,movement and splicing are introduced.The structured light technique was applied to the FINCH holographic imaging and theoretical was analyzed,The imaging process was simulated by using the MATLAB,which realized the expansion of the frequency domain in horizontal and vertical directions in the holographic imaging,and then improved the resolution of the reproduced image.The feasibility that structured light technology applied in the holographic imaging systems to realize super resolution was verified.