Extending The Depth Of Field By Using Liquid Crystal Lens And Its Application

Liquid crystal lens as a new optical imaging element has been widely used in photography,microscopic imaging,virtual reality and other fields.In the field of imaging,the structure of the imaging system is greatly simplified and the focusing efficiency is improved by the electrically controlled focusing property of the liquid crystal lens.In addition,methods of extending the depth of field by using liquid crystal lens have been realized.In this paper,a new method of extending the depth of field is proposed,which based on the depth measurement technology of liquid crystal lens.The main research work of this paper is as follows:In this paper,a new polarizer-free imaging model based on unsharp masking model has been proposed.The traditional polarizer-free imaging algorithm determines the processing intensity of the source image by detecting the noise of the result.This method can not accurately reflect the influence of the algorithm on the different processing intensity of the source image,and it is difficult to obtain the optimal result.In this paper,the principle of the polarizer-free imaging algorithm is analyzed,and a new model of the polarizer-free imaging algorithm is proposed based on the unsharp masking process.The model can accurately reflect the influence of different processing intensity on the results according to the change of contrast in the local area of the result,and help us to select an optimal processing intensity.At the same time,this model can also be used to detect the ratio of o light and e light of incident light.In this paper,an image capture method of extending the depth of field based on defocus method of liquid crystal lens is realized.The liquid crystal lens system can capture all-in-focus images by using the image fusion method,which needs to change the power of the liquid crystal lens to capture the images with different focal planes.Traditional image capture methods,which are used for image fusion,based on depth-offield or time.The method based on depth-of-field needs to set a set of voltages to get images which have conterminous depth-of-field.This set of voltages is closely related to the geometrical relationship and parameters of the optical elements.They need to be reset when the related parameters change.And the method based on time captures too large number of images,wastes a lot of time on calculations and generates a lot of redundant information.This paper proposed a new image capture method based on the depth measurement method according to the relationship between the depth of the object in the scene and the power of the liquid crystal lens.The depth image was calculated by the depth from defocus method of the liquid crystal lens,and the relationship of the depth,the power and driving voltage was derived.The voltage was set and the focusing image was captured.This method greatly reduces the number of images captured and the redundant information,and improves the computational efficiency.Then,a salient object detection method based on depth image is proposed,and the image quality is evaluated for the salient area of the object in the all-in-focus images obtained by different image capture methods.In addition,a refocusing method based on liquid crystal lens is proposed.This method refocus the all-in-focus image by rendering the all-in-focus image according to the depth of different objects in depth image.Then,the normal image and the refocus image were compared and evaluated.