Application Of Pupil Modulation Technique To Improve The Resolution Of Fundus Imaging

The eye is an important organ of human beings.On the one hand,it can obtain information from the outside;on the other hand,it can transfer the imformation about the human body to the outside.The resolution is greatly improved since the adaptive optics is applied in vivo visualizationoftheretina.It is of great medical significance for the prevention and treatment of related diseases to further improve the resolution of retinal images.The effect of pupil filter on the reduction of the width of the main lobe and the sidelobe suppression characteristic of confocal microscopy make it possible to apply the phase modulation technology in the confocal laser ophthalmoscope pupil for improving the image resolution.Based on this method,we study the confocal scanning optical imaging theory and the pupil modulation super-resolution imaging theory,design an adaptive confocal laser ophthalmoscope with two light sources and make some experiments on the phase modulation to improve resolution.We finally realize the application in retina imaging,and also make preliminary research on dark field imaging on the basis of the preliminary study.Firstly,the point spread function and the coherent transfer function of the reflection confocal mirror are derivedbased on the single lens imaging theory,and then the pupil modulation super-resolution theory is studied.By analyzing and comparing the super resolution performance of different pupil filters,the parameters of the phase filter are determined.The influence of the two-zone phase pupil filters on the coherent transfer function and the point speard function is further calculated and analyzed.In addition,the changesin the image quality and the influence of Gauss beam distribution on the coherent transfer function are also studied.According to the experimental requirements,we design an adaptive confocal laser ophthalmoscope with two light sources to realize the independence of the imaging light and the light for wavefront detection,thus the aberration can be corrected and phase modulation can be realized at the same time.The two light sources are analyzed under the limitation of eye safety exposure dose,and the major aberrations of the two light sources are calculated,which offers the reference for the aberrations correction.The liquid crystal phase modulator is used to realize the function of the phase pupil filter,and thenthe phase modulation system is designed and the error analysis is carried out.We gradually build a super resolution confocal laser ophthalmoscopebased on the above theory.the aberration correction function of the system and the influence of pinhole on the imaging quality are studied respectively by taking the artificial eye as the imaging object.Then the phase modulation is applied to the pupil and the exit pupil respectively,and then the images of the artificial eye are analyzed to verify the imaging theory.Finally,we take the living human eye retina as the observation target,get the high-resolution image after closed loop system,and further applyphase modulationin the entrance pupil to improve the resolution of retinal images.Finally,based on the adaptive confocal ophthalmoscope with two sources,we studied the feasibility of obtaining the dark field imagesin vivoimagingsystem.We made a theoretical analysis on the dark field imaging,and further analyze the maesure to getthe dark field image and differential phase contrast image.Finally,we have carried out a theoretical verification experiment on the simulated human eyeand get the bright and dark field image of the artificial eye.