A Research On Foveated Imaging System Using Liquid Crystal Lens

Imitating the vision of human retina,foveated imaging system is an optical system which can maintain a multi-resolution photograph while keeping large field of view.in the image of this kind of foveated system,the resolution of region of interest is higher than that of periphery area.Compared with traditional imaging system,the foveated imaging system has advantages of large-field of view,high-resolution,small data quantity and so on.Therefore,it has gained a lot of attention from domains as surveillance,navigation,robotics,and target tracking.Because liquid crystal lens works as the electric field controls the rotation of liquid crystal molecules,we can achieve lens effect in a large transparent liquid crystal cell to realize fovea imaging.The liquid crystal lens foveated imaging system is formed by combining liquid crystal lens with traditional glass lens module and works when liquid crystal lens focuses on local region of full image.This liquid crystal lens imaging system can be electrically controlled focusing and is compact,easy-built and stable while having a long working life.Nowadays liquid crystal lens fovea imaging systems still have much problem unsolved,such like the area and position of regions of interest in the foveated system which can be of great importance in reality application scenes.Therefore,in this paper we discus about the high-resolution area and key issues of image quality in the liquid crystal lens fovea imaging system.The contents are divided into three parts shown as follows.First,the imaging elements used in the liquid crystal lens foveated imaging system have been improved and the multi-position multi-high-resolution-region fovea imaging has been realized by using image-space telecentric lens and separately controlled liquid crystal lens array.In the liquid crystal lens array the elements can work both in the positive and negative focus mode at the same time.Compared with precious liquid crystal lens fovea systems,it has a smaller aberration and enhances the system imaging quality.Secondly,some researched has been done on the effective area size of the fovea system using liquid crystal lens in which it is a quite important parameter in the system.Through the deduction of the different areas imaging conditions we can get the calculation formulas of imaging areas in different cases.Comparing the image positions and areas in different conditions with each other,we can deduce the formula of effective area in this liquid crystal lens foveated imaging system.Also imaging experiments compared with theoretical results are performed to prove the effective area theory.Finally,focused on the problem that the light from periphery area around liquid crystal lens decrease imaging quality of effective area in fovea system,in this paper we have designed and produced a liquid crystal device combining a liquid crystal aperture and a liquid crystal lens together to replace the original liquid crystal lens array.By controlling the passing light from periphery areas using the liquid crystal aperture,with the time-shared imaging mode dividing images into liquid crystal lens and periphery area,the resolution in the fovea image can be improved.